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Wear is one of the main problems encountered in industrial operations, generating high costs due to equipment failures for constant replacement of parts. By implementing technologies designed to enhance wear resistance, losses can be minimized in industries such as mining, cement, sugar and ethanol, and steel production. A key solution to reducing maintenance costs from wear is the application of highly abrasion-resistant alloys through welded hardfacing on coated sheets. Therefore, the objective was to investigate the microstructure and wear resistance of two high chromium hardfacing alloys with Fe–C-Cr and Fe–C-Cr-Nb-B systems used in the manufacture of wear resistance, deposited using tubular wires. This study also aims to assess the variation in wear rate based on the alloy composition in the coatings. Firstly, the characterization of the materials was carried out through chemical and microstructural analysis through scanning electron microscopy (SEM), X-ray diffraction (XRD), and hardness. A comparative analysis of the friction coefficient and wear resistance was carried out using the ASTM G133–Linearly Reciprocating Ball-on-Flat Sliding Wear test, where the worn volume was analyzed by optical profilometry. The Fe–C-Cr-Nb-B system alloy presented higher hardness values and lower volume loss than the Fe–C-Cr system alloy due to the presence of niobium primary carbides dispersed throughout the coating, promoting greater matrix protection and, consequently, less abrasive wear. The results were coherent and provided data that can lead to a better selection of materials among solutions in the manufacture of wear-resistant sheets and hard coatings deposited by welding in the industry. [ABSTRACT FROM AUTHOR]

The wind turbine blades are exposed, during functioning, to the abrasive wear generated by the impact with air-borne sand particles. In this work, samples of a commercial wind turbine blade, made of a multi-layered composite material, are subjected to abrasive wear tests, using an air streamed wearing particles test rig. Following the analysis of the tests' results was found that the only protection against failure of the blade by abrasive damage is the surface layer. After its' penetration, the layers below are quickly destroyed, leading to the blade destruction. The investigation of the main abrasive wear influencing factors—particles' speed and acting time, showed that the particles' speed is the most important. To prove that an artificial neural network-based model was used. Also, a method for improvement of the blade resistance to abrasive wear is proposed, consisting of applying on the blade's surface of a polymeric foil. This offers supplementary protection of the surface layer, delaying its degradation. The tests performed on the protected samples prove the validity of the proposed method. Overall, the work showed the weakness of the blades' resistance in case of working in abrasive wear conditions and identified an improving method. [ABSTRACT FROM AUTHOR]

High-strength martensitic steels with boron are among the leading materials widely recognized for their exceptional resistance to abrasive wear. These steels exhibit some of the highest strength indices among bulk steels, a result of their specific chemical composition, thermomechanical rolling processes at the steel mill, and the use of pure, high-quality ores. With hardness values ranging from 400 to 650 HBW, they are ideal for demanding applications such as excavator buckets, plow blades, shafts, wear-resistant bars, and container liners. One critical microstructural property contributing to their high mechanical performance is the prior austenite grain size (PAG). A finer grain structure is associated with enhanced plasticity, and plastic deformation plays a significant role in abrasive wear mechanisms. However, this relationship between grain size and wear resistance is not well-documented in the literature, with few studies providing specific quantitative data. To address this gap, the authors conducted a study to examine the effect of prior austenite grain size on wear resistance when exposed to loose abrasive electrofused alumina no. 90. The findings indicate that applying targeted heat treatment can increase hardness by 58 Brinell units compared to the as-delivered condition. Moreover, as grain size increases from 18 µm to 130 µm, the relative abrasive wear resistance coefficient Kb decreases from 1.00 (for Hardox 500 steel in its as-delivered state) to 0.80 for austenitized material treated at 1200 °C. [ABSTRACT FROM AUTHOR]

The purpose of this investigation is to see how varying percentages of Graphene Nanoplatelets (GNP) affect the wear behaviour of carbon fibre reinforced epoxy (CFRE) composite. The hybrid nano composites were developed using hand layup process followed by compression moulding. Furthermore, the impact of operational parameters such as load and abrading distance against SiC paper of 220 grit size at a rotational speed of 200 rpm was investigated. It was found that incorporating a considerable amount (up to 0.5 wt. %) of GNP significantly improved the wear performance of CFRE composites. There is increase in wear loss again for 0.75 and 1.0 wt. % GNP. The morphology of developed nano hybrid composites were linked to data patterns on wear volume and specific wear rates. GNP addition up to 0.5 wt. % strengthened the fibre-matrix interface, preventing simple fibre pull-out from matrix/fillers and enabling increased wear resistance, according to worn surface characteristics investigation. [ABSTRACT FROM AUTHOR]

Among the materials used for components subjected to abrasive wear, chromium cast iron, hardfaced layers, martensitic steels and Hadfield steel should be singled out. Each of these types of materials exhibits a different morphology of structure and strength properties. Hadfield steel, characterized by an austenitic microstructure, shows the ability to strengthen the subsurface layers by cold work, while maintaining a ductile core. Hardox steels belong to the group of low-alloy martensitic boron steels. However, it should be noted that increasing hardness does not always translate into low wear values due to a change in the nature of wear. In view of the above, the authors decided to subject selected Hardox steels and Hadfield cast steels in the post-operational condition to abrasive wear tests in the presence of loose abrasive. The study showed that Hardox Extreme steel exhibits the highest resistance to abrasive wear (value of the coefficient kb is equal to 1.39). In the case of Hadfield steel, the recorded values are slightly lower (kb = 1.32 and 1.33), while the above ratios remain higher compared to Hardox 600 and Hardox 500 steels. The main wear mechanism of high-manganese steels is microploughing, plastic deformation and breakouts of larger fragments of material. In the case of Hardox 450 and Hardox 500 steels, the predominant wear mechanisms are microploughing and breaking out of material fragments. As the hardness of the steel increases, the proportion of wear by microcutting and scratching predominates. [ABSTRACT FROM AUTHOR]

Polyurethane coatings are widely used as protective layers against wear, mainly abrasive wear. They have recently been applied to surfaces exposed to erosive wear, such as wind turbine blades. This study investigated the abrasive and erosive wear of polyurethane elastomeric coatings with hardness values of 55 ShA, 75 ShA, and 95 ShA. The abrasive wear test was carried out using loose abrasive grains. The erosive wear test was carried out using a pressurized stream of gas containing abrasive particles. Both tests were carried out using aluminum oxide grains of five different sizes to evaluate the effect of particle size on wear behavior. Microscopic and profilometric analyses of the surface of the wear tracks were carried out. The mechanism of abrasive and erosive wear of polyurethane elastomeric coatings was determined. The results of the tests show a non-linear dependence of abrasive and erosive wear on the grain size. Furthermore, polyurethane elastomer coatings with a higher hardness exhibit a lower abrasive wear resistance but higher susceptibility to erosive wear. These findings provide insight into the trade-offs between hardness and wear performance, offering practical guidance for selecting polyurethane coatings in applications requiring resistance to combined abrasive and erosive wear. [ABSTRACT FROM AUTHOR]

In materials science, steel boration is a promising type of thermochemical diffusion process, the purpose of which is the introduction of hard and wear-resistant boride particles into the surface layers of the metal. The main disadvantage of boration is the fragility of borated layers, especially boride. Currently, there are promising methods for the formation of a composite structure, which are based on the treatment of surface layers of steels with concentrated energy flows (laser, electron beam and plasma). The work includes studies of microstructure, hardness measurements, analysis of phase composition, and determination of chemical composition in local locations, wear tests under various conditions, and adhesion testing of the coatings obtained after plasma boration. As the degree of alloying of the molten layer decreases in the direction from the surface to the base metal, zones of overeutectic, eutectic and pre-eutectic types with a different combination of structural components are formed. The material obtained after borating a mixture of 40% B + 10% Fe is characterized by the highest level of microhardness, which is 1000...1300 HV. The highest results in friction tests are provided by boration of a powder mixture of 40% B + 10% Fe.

SiMo ductile irons, typical heat-resistant materials, are subjected to varied wear environments during operation in high-temperature applications. SiMo ductile iron castings of different thicknesses were cast in investment and greensand molds, achieving a wide range of cooling rates. The present work aims to investigate the effect of the cooling rate and alloying elements (Cr, V, and Ni) on the microstructure and the abrasive wear behavior of these grades of SiMo ductile iron at high-temperature 700 °C under different loads. Thermodynamic calculations were used to propose the phase diagrams, critical transformation temperatures, and phase volume fractions in all SiMo alloys by using the Thermo-Calc software then verified by and Differential Scanning Calorimetry (DSC). The microstructure of unalloyed SiMo ductile cast iron consists of graphite nodules and carbides embedded in the precipitates at the grain boundary regions in a ferrite matrix. The alloyed SiMo microstructure contains nodular graphite and the carbides promoted by the alloying elements (Cr and V). The alloyed SiMo alloys exhibit higher wear resistance than unalloyed ones. These wear results support that the microstructure plays a chief role in wear loss. The combination of M6C, VC, and M7C3 carbides embedded in a ferrite-pearlite matrix (alloyed SiMo) seems to be more resistant to wear than the ferritic matrix with lamellar pearlite and eutectic M6C carbides (unalloyed SiMo). [ABSTRACT FROM AUTHOR]

This article presents the results of abrasion wear resistance tests of wear-resistant steel and surfacing under laboratory conditions and natural operation. Abrasion wear resistance determined on the basis of the study by determining geometrical characteristics of the alloying additives using computer image analysis methods, as well as examining the changes occurring on the surface of the workpieces and their wear intensity. Based on the results obtained from laboratory tests, it was noted that AR steel exhibited 14 times greater wear than the padding weld. This wear is affected by alloy additives, which, for the padding weld, are chromium additives. The microstructure image shows that soil mass had a destructive effect mainly on the matrix of the material, whereas in the areas with high concentrations of chromium precipitates, this effect was significantly weaker. The operational test results showed that within the area of the tine subjected to hardfacing, the material loss was lower than that for the same area of the tine in the as-delivered state. For the hardfaced tine, a 7% loss of volume was noted in relation to the operating part before testing and following the friction process. However, for the operating part in the as-delivered state, this difference amounted to 12%. [ABSTRACT FROM AUTHOR]

As a contribution of recycling of polymers in the automotive industry, recycled polyvinyl butyral (rPVB) from automotive windshields is being explored as a solid lubricant reinforcement for improving lubricity of engineering polymers. This work aims to evaluate the tribological behavior (coefficient of friction [CoF] and wear resistance) of polyamide 6 (PA6) and glass-fiber-reinforced polyamide 6 (PAGF) blended with rPVB as solid lubricant under two-body and three-body abrasive conditions. The different polymer blends were produced by adding recycled polyvinyl butyral (rPVB) into a matrix of either a commercial polyamide 6 (PA6) or a commercial 30% glass-fiber reinforced polyamide 6 (PAGF). The tribological tests were conducted in an instrumented microabrasion tester for generating wear and measuring the coefficient of friction (CoF) in both dry and microabrasion conditions. In the dry condition, rPVB was effective in reducing the CoF for both PA6 and PAGF. Two-body abrasion was found as the predominant wear pattern in the dry condition. On the other hand, in the microabrasion condition, the additions of rPVB were not totally effective since they produced a wear resistance increase for PAGF but a reduction for PA6, which was ascribed to a notable decrease in toughness for PA6 when adding rPVB. Well-defined plowing traces and several SiC particles embedded in the scars were the predominant patterns in all the materials. In both PA6 and PAGF, CoF increased with the rPVB additions. [ABSTRACT FROM AUTHOR]

The results of the study of patterns of destruction and their influence on the wear resistance of low-alloy steel 65G in the unstrengthened state, as well as after strengthening by thermal and electroerosion treatment during movement in soils of different fractional composition, are presented. It has been confirmed that under such conditions the phenomenon of the presence of a critical size of abrasive particles (CPS) is realized on the wear surface. The role of the geometric size of the particles in the formation of the wear resistance of steel consists in the regulation of active deformation and fatigue phenomena on the wear surface by changing the level of force acting on it. The influence of the fractional composition of the soil on wear resistance is carried out through the rheological fatigue parameter in the following dependence: the greater the rheological-fatigue parameter, the higher the wear resistance of steel. Therefore, the mechanical component of the contact interaction is decisive in the strength basis of the wear mechanism. Therefore, when choosing a brand of low-alloy steel for the manufacture of machine parts intended for operation in soils of different fractional composition, it is necessary to be guided by its ranking according to the rheological-fatigue parameter. The role of the fractional composition of the soil in the formation of the rheological- fatigue parameter is carried out mainly through the cyclic viscosity of deformation in the sublayer of nonlinear effects in the vicinity of the crack tips of the surface layer in the following dependence: the higher the cyclic viscosity, the lower the rheological-fatigue parameter of steel. The stress that is cyclically repeated during abrasive wear causes in the sublayer of nonlinear effects in the vicinity of the crack tips of the surface layer two opposite phenomena that occur simultaneously: strengthening and weakening. At the same time, the action of the weakening process in soils of different fractional composition is more effective than strengthening. In the region of the subcritical geometric dimensions of the abrasive particles, the intensity of hardening is significantly reduced due to the increase in the effectiveness of the hardening action due to the additional contribution of dispersion hardening. However, this does not entail qualitative changes in the wear process. [ABSTRACT FROM AUTHOR]

This article presents the effect of the conditions of abrasive compounds on the wear of samples made by different methods. The 28MnB5 steel was used, which is intended for agricultural components, to which two arc and laser coatings were applied. The study included the analysis of microstructure, microhardness, roughness, and tribological experiments on a dedicated stand. The arc coating was found to significantly improve the tribological properties compared to the samples without the coating. Varied wear results were obtained for the laser coating depending on the parameters of the abrasive compound. Studies of the surface roughness of the samples showed that the concentration and pH of the abrasives have a significant effect on the changes in the surface parameters after the tribological tests. The results of the tribological experiments indicated that wear resistance for some of the abrasive mass conditions was improved by the application of heat-applied coatings. In addition, it was found that the power consumption on the stand was the highest for abrasive mass conditions of a 10% moisture content and a pH of 10. For these test conditions, the mass loss was four times higher than for the parameter with W0% and pH7. The energy consumption of the stand was 60 kWh lower for this variant than for the parameter with W10% and pH10. The results of the study have important practical applications that can help in the selection of materials for agricultural machinery components, depending on the abrasive mass conditions. [ABSTRACT FROM AUTHOR]

The wear resistance of quenched-and-partitioned steel (Q&P) compared to martensite steel (Q&T) remains unclear. In this research, the wear resistance of Q&P steel and Q&T steel was researched by the means of the abrasive wear (AW) and impact abrasive wear (IAW) tests. The results show that abrasive ploughing was the main reason causing the material loss of Q&P and Q&T steel, while Q&T steel was subjected to severe fatigue spalling in the impact abrasive wear tests. Under the abrasive wear test, Q&T steel has better wear resistance due to its higher initial hardness. Under the impact abrasive wear test, Q&P steel has better wear resistance. This is because the formation of the deformed layer, which consists of finer grains and newly formed martensite in the worn subsurface, increased the hardness of the Q&P steel, causing the hardness of the worn subsurface in Q&P steel to be higher than that of Q&T steel. Furthermore, Q&P steel has better resistance to cracks nucleation and propagation compared to Q&T steel. As a result, less material loss was caused by fatigue spalling in Q&P steel under the impact abrasive wear tests. [ABSTRACT FROM AUTHOR]

Martensitic low-alloy steels are widely used in machine construction. Due to their declared weldability, arc welding is most often used to join elements made of this type of steel. However, the high temperature associated with welding causes unfavourable changes in the microstructure, resulting in reduced abrasion resistance. Therefore, it is important to know the tribological properties of the welded joint. This article presents the results of a study on the abrasion wear resistance of a welded joint of an abrasion-resistant steel. This study tested a welded joint of an abrasive-resistant steel produced by the arc welding method. Wear testing of the welded joint was carried out under laboratory conditions by the ball-cratering method in the presence of abrasive slurry on the cross-section of the welded joint. Based on the test results, the change in the abrasive wear rate of the material as a function of the distance from the welded joint axis was determined. It was also found that the thermal processes accompanying welding caused structural changes that increased the wear rate index value. Adverse changes in the tribological properties of a welded material persist up to a distance of approx. 20 mm from the weld centre. [ABSTRACT FROM AUTHOR]

Ni60-WC coatings with different WC contents on the bucket tooth substrates were pre- pared using laser cladding technology. Their abrasive wear properties were assessed using the dry sand rubber wheel test system. The substrate and the hard-facing layer were tested for comparison. The results showed that the hardness of the Ni60-WC coatings increased with the increase in WC content. The wear resistance of the bucket tooth substrate was greatly improved by hard-facing and laser cladding Ni60-WC coatings. The wear rate of the hard-facing layer was reduced to 1/6 of that of the tooth substrate. The wear rate of the laser cladding coatings with 20–40 wt.% WC was similar to that of the hard-facing layer. It is worth mentioning that the wear rate of the coatings with 60–80 wt.% WC was only 1/4 of that of the hard-facing layer. Micro-cutting with surface plastic deformation was the main wear mechanism of the substrate to form narrow and deep furrows. The wear mechanism of the hard-facing layer was mainly plastic deformation with a wide groove, and the surface cracks promoted the removal of the material. The removal of the binder phase caused by micro-cutting was the main wear mechanism of the laser cladding Ni60-WC coatings. However, the hard phase of WC hinders micro-cutting and plastic deformation, which improves the wear resistance of the coating. [ABSTRACT FROM AUTHOR]

Two chromium-rich carbide hard-faced plates, alloy—A and alloy—B, were subjected to a 3-body dry sand abrasion test. The difference was in the coating microstructure. Alloy-A contains globular chromium carbide (M7C3 type) in the austenite matrix, whereas alloy—B is composed of a banded structure with an alternate layer of carbide and austenite. Alloy B showed a superior abrasion resistance (nearly 40%) than alloy—A. A detailed microstructural investigation was made on the abraded surface. The higher abrasive wear resistance of alloy-B was attributed to the coating morphology, the composite-like microstructure resulted in an effective strain distribution among the austenite matrix and carbides. This postulate was supplemented by higher average misorientation, which was observed at sub-surface regions of the worn-out specimen, leading to form a strain-induced martensite. However, in alloy—A, the abraded surface contained abundant broken carbides. [ABSTRACT FROM AUTHOR]

The surface features of additively manufactured polymer parts differ compared to extruded polymer parts and decide their performance in terms of power transmission applications. Layer thickness is one of the important process parameters chosen based on the part complexity and production speed, influencing the surface features. The abrasive wear performance of high-performance polyether ether ketone (PEEK), which determines the performance of power transmission elements such as bearings and gears, is reported in this article. The layer thickness employed in fabrication, which varies from 0.1 mm to 0.35 mm, influences the surface roughness, real contact area, and hardness of the as-printed PEEK. The friction coefficient and wear resistance of a printed part are influenced by the layer thickness employed, indicating the need for a proper choice of layer thickness for power transmission applications. Samples printed with a layer height of 0.25 mm and higher exhibited an increase of friction coefficient and wear loss due to the weak surface integrity. The friction and wear characteristics of additive manufactured samples are compared with extruded samples. Wear debris accommodation in the grooves of the as-printed surfaces accelerates the wear due to three-body abrasion in high layer thickness samples. The micromechanisms of wear damage in different layer thickness samples are discussed. The observations indicate the strong influence of layer thickness and facilitate the selection of appropriate layer thickness for the required friction coefficient in a particular application. [ABSTRACT FROM AUTHOR]

The rapidly developing mining industry poses the urgent problem of increasing the energy efficiency of the operation of basic equipment, such as semi-autogenous grinding (SAG) mills. For this purpose, a large number of studies have been carried out on the establishment of optimal operating parameters of the mill, the development of the design of lifters, the rational selection of their materials, etc. However, the dependence of operating parameters on the properties of the ore, the design of the linings and the wear of lifters has not been sufficiently studied. This work analyzes the process of grinding rock in SAG mill and the wear of lifters. The discrete element method (DEM) was used to simulate the grinding of apatite-nepheline ore in a mill using different types of linings and determining the process parameters. It was found that the liners operating in cascade mode were subjected to impact-abrasive wear, while the liners with the cascade mode of operation were subjected predominantly to abrasive wear. At the same time, the results showed an average 40–50% reduction in linear wear. On the basis of modelling results, the service life of lifters was calculated. It is concluded that the Archard model makes it possible to reproduce with sufficient accuracy the wear processes occurring in the mills, taking into account the physical and mechanical properties of the specified materials. The control system design for the grinding process for SAG mills with the use of modern variable frequency drives (VFD) was developed. With the use of the proposed approach, the model predictive control (MPC) was developed to provide recommendations for controlling the optimum speed of the mill drum rotation. [ABSTRACT FROM AUTHOR]

Simultaneously improved impact toughness and wear resistance of high Cr tool and die steels (HCS) enable them to be widely used in the lightweight field. In this study, TiC + TiB 2 /HCS steel was prepared by pre-dispersed ceramic nanoparticles combined with specific heat treatment. The effects of ceramic nanoparticles on the microstructures, mechanical properties and wear resistance of TiC + TiB 2 /HCS steel were investigated by comparing it with shield machine tool steel (H13 steel). The results demonstrated that the introduction of ceramic nanoparticles refined the microstructure of the TiC + TiB 2 /HCS steel and uniformed the distribution of the precipitates. For TiC + TiB 2 /HCS steel and H13 steel with the equivalent hardness values, the impact toughness and the wear resistance of TiC + TiB 2 /HCS steel were 67.3 % and 39.5 % higher than that of H13 steels, respectively. Moreover, when the wear resistance was comparable, the impact toughness of TiC + TiB 2 /HCS steel was 89.1 % higher than that of H13 steel. This study provides an innovative solution to prepare high-service performing service life tools and die steels to replace shield machine tool steels. • Using pre-dispersed ceramic nanoparticles combing specific heat treatment to fabricate TiC + TiB 2 /HCS steel. • Refined matrix microstructure, finer carbides were obtained and more uniform dispersed of TiC + TiB 2 /HCS steel. • Comprehensive performance including hardness, toughness and wear resistance of TiC + TiB 2 /HCS steel was improved. [ABSTRACT FROM AUTHOR]

Rutting is the most common and most dangerous defect of asphalt pavements. One of the problems of northern countries such as the Russian Federation is abrasive rut due to studded tire loading. Precise prediction of the asphalt concrete abrasion and wear resistance allows improving the durability and reliability of asphalt pavements. Several laboratory tests are used for the prediction of asphalt concrete abrasion resistance. An abrasive wear model of asphalt concrete is needed to predict wear resistance changes under different conditions. The aim of this article is to evaluate compaction quality effect and air voids value on the abrasion resistance of asphalt concrete. To estimate the influence of the percentage of connected voids on abrasive wear of asphalt concrete, an asphalt wear model was presented. This model is based on G.Y. Lee’s approach. This approach divides the abrasive processes into normal abrasion and particle loss. Air voids lead to the aggregate loss and affect the abrasion resistance of the asphalt pavements. Calculation of these effects is possible using G.Y. Lee’s approach. Calculations of the lost particles include the empirical coefficient (1/mm) characterizing the influence of the pores on the lack of adhesion to the aggregate particle surface and the influence of the lack of adhesion on the fraction of lost particles. The Prall test was used for the abrasion resistance estimation. The saturation degree method was used for the estimation of compaction quality and air voids content. For the coefficient estimation, 63 samples of different mixes were tested. The mixes were used for the construction of the Republic of Tatarstan road network. The used asphalt concretes correspond to requirements of Russian standards GOST 9128-2013 and GOST 31015-2002. The experiments show good reliability of the presented model. This model predicts abrasion resistance of asphalt concretes under uncompaction and provides insight into the abrasive wear processes in the asphalt concretes. Furthermore, the study results allow us to improve the laboratory tests precision by 2.3 % by excluding the uncompaction effect during the comparison of the results.

High-silicon and molybdenum (SiMo) ductile iron is a common heat-resistant alloy that may be exposed to high-temperature wear during service in many of its applications. The wear behavior of four SiMo ductile iron alloys was evaluated at different temperatures up to 750 °C. This research focuses on the influence of various Mo contents on the microstructure, structural stability, and hence, the wear performance of such alloys. Thermodynamic calculations proposed the phase diagrams, critical transformation temperatures, and phase volume fractions in all samples by means of Thermo-Calc software. The dilatometry measurements were carried for confirming the theoretical results of Thermo-Calc thermodynamic calculations. The results revealed that the microstructure of SiMo ductile cast iron consists of nodular graphite and a ferrite matrix with carbides embedded in the fine precipitates at the grain boundary regions. The type of carbides and the nature of these fine precipitates are discussed according to EDX and SEM results. Adding molybdenum enhanced the wear performance of SiMo by decreasing the weight loss by about 40–70% compared to a Mo-free alloy. This is due to the increased molybdenum carbides, which increase hardness and improve wear resistance in SiMo alloys. The high temperatures have a negative effect on reducing the wear resistance at 250 °C. On the other hand, the wear resistance unexpectedly started to increase at higher temperatures of 500 °C and 750 °C because of the contribution of oxidative wear with abrasive wear by forming a protective oxide layer. Furthermore, the obtained results supported the idea that adding molybdenum improves wear resistance at high temperatures. Hence, SiMo has the potential to be wear-resistant material in wider applications requiring high-temperature wear resistance. [ABSTRACT FROM AUTHOR]

Böhler K390 steel is used for cold work tools, with 9% of V, made by using powder metallurgy. In this work, it has been studied the effect of shot peening and nitriding surface treatments on wear resistance and impact toughness of this type of steel. For this purpose, previous changes in several thermal processing factors related to quenching and tempering were carried out. The results allow for an increase in the hardness, impact toughness, and abrasive wear resistance of these steels. An austenitizing treatment at 1100 °C with air cooling and 3 tempering processes at 550 °C is suggested. These conditions foster a lower weight percentage of retained austenite, up to 3%, a higher carbide percentage, up to 15–16% in weight, and a greater impact toughness with no notch, of above 40 J/cm2. If this treatment is combined with further ion nitriding, the maximum level of abrasive wear resistance is reached. The only carbide type present in the microstructure is the MC type. Most of the V, Cr, and Mo contents are present in said carbides. The Co and the W tend to remain in solid solution in the matrix constituent. Both the shot peening treatment as well as ion nitriding offer a considerable increase in hardness, with values of up to 1500–1600 HV. Nevertheless, it has been confirmed that shot peening does not offer any abrasive wear resistance improvement. Such resistance may only be considerably improved by the application of an ionic nitriding treatment. The thickness of the nitrided layer fluctuates between 150 and 175 µm. The carbides are affected by nitriding, reaching levels that are higher than the atomic 10%, at an intermediate depth of the nitrided layer. These values are higher in the matrix constituent, as they are even higher than the atomic 20% in N. [ABSTRACT FROM AUTHOR]

In order to reveal the effect of alkali treatment of walnut shell (WS) powder and attapulgite (ATP) hybrid filling on the properties of WS/polyvinyl chloride (PVC) composites, and to compare the effects of different reinforcement methods, WS/PVC composites were prepared by single screw melt extrusion. Furthermore, analysis was conducted on the chemical composition, thermal stability, microstructure, and physical, mechanical and wear resistance properties of composites. The results showed that ATP hybrid can enhance the performance of WPC more effectively than alkali treatment, unmodified WS blended with ATP composites have the best physical, mechanical properties, abrasive wear resistance, as well as lower water absorption, compared with the untreated, the tensile strength, bending strength and impact strength increased by 24%, 8%, and 21%, respectively. In addition, the composites of ATP hybrid alkali treated WS have the best thermal stability, and its pyrolysis residue is 15.64% higher than untreated composites. The study found that ATP have a larger potential to enhance the properties of composites than alkali treatment. Highlights: Chemical treatment and inorganic mineral particle filling were used to enhance the properties of the WS/PVC composites.The experimental results showed that attapulgite can maximize the properties of the composites without alkali treatment. This means that attapulgite filling is a more effective and environmentally friendly and simple method to enhance the properties of composites than alkali treatment.The wear failure modes of the composites are mainly micro‐indentation and micro‐cutting. [ABSTRACT FROM AUTHOR]

To enhance the wear resistance of H13 steel (4Cr5MoSiV1), Co6, T400, and Ni-based 30WC coatings were applied to the surface of H13 steel using laser cladding technology. The microstructures and phase compositions of the three coating types were analyzed using SEM and XRD methods. The high-temperature friction and wear performance of the three coated samples and H13 steel were measured through high-temperature friction wear tests, and the friction wear types of the four samples were analyzed. A comparative analysis of experimental data led to the following conclusions: (1) Among the four samples, the Ni-based 30WC-coated sample exhibited the best self-lubricating properties. (2) The average wear area of H13 steel was 0.059 mm2, and the wear volume was 0.29 mm3; the average wear area of Co6-coated samples was 0.050 mm2, and the wear volume was 0.25 mm3; the average wear area of T400-coated samples was 0.002 mm2, and the wear volume was 0.01 mm3; and the average wear area of the Ni-based 30WC-coated sample was 0.035 mm2, and the wear volume was 0.17 mm3. In terms of wear resistance, the ranking from highest to lowest was: T400-coated sample > Ni-based 30WC-coated sample > Co6-coated sample > H13 steel. (3) Based on the classification of friction wear types, H13 steel primarily exhibited adhesive wear and oxidized wear; the Co6- and T400-coated samples primarily showed adhesive wear, abrasive wear and oxidized wear; and the Ni-based 30WC-coated sample mainly exhibited abrasive wear and oxidized wear. [ABSTRACT FROM AUTHOR]

Thermomechanical action during high-performance diamond grinding of sintered cutting Al2O3/TiC and SiAlON ceramics leads to increased defectiveness of the surface layer of the deposited TiZrN and CrAlSiN/DLC coatings. It predetermines the discontinuous and porous coatings and reduces its effectiveness under abrasive exposure and fretting wear. The developed technological approach is based on "dry" etching with beams of accelerated argon atoms with an energy of 5 keV for high-performance removal of defects. It ensures the removal of the defective layer on ceramics and reduces the index of defectiveness (the product of defects' density per unit surface area) by several orders of magnitude, compared with diamond grinding. There are no pronounced discontinuities and pores in the microstructure of coatings. Under mechanical loads, the coatings ensure a stable boundary anti-friction film between the ceramics and counter body that significantly increases the wear resistance of samples. The treatment reduces the volumetric wear under 20 min of abrasive action by 2 and 6 times for TiZrN and CrAlSiN/DLC coatings for Al2O3/TiC and by 5 and 23 times for SiAlON. The volumetric wear under fretting wear at 105 friction cycles is reduced by 2–3 times for both coatings for Al2O3/TiC and by 3–4 times for SiAlON. [ABSTRACT FROM AUTHOR]

A methodology has been developed for obtaining of porous castings from Al and aluminium A356 alloy. The methodology includes introduction of Ca into the melt for viscosity increasing and homogenization by mechanical stirring. This is followed by addition of TiH2, homogenization, subsequent formation of the porous structure and crystallization. A tomographic analysis of the porous samples was carried out and the main characteristics of their structure were determined. Tests were carried out on specimens of the castings involving abrasive wearing under dry friction conditions on a surface with hard-attached abrasive particles. [ABSTRACT FROM AUTHOR]

Objective: Wear and surface hardness of resin composites are of relevance from the clinical standpoint. With the incorporation of novel filler system, more studies need to be performed to investigate newly marketed resin composites. The objective of this study was to investigate the abrasive wear and surface hardness of dental restorative with different filler types. Methods: Nanohybrid filled Harmonize (HM) and Tetric N-Ceram (TNC), microhybrid filled Filtek Z250 (Z250), nanofilled Filtek Z350 (Z350) were included in the study. Twelve cylindrical resin composites specimens with 10 mm in diameter and 6 mm in thickness were prepared for abrasive wear test. Eight hundred cycles under 17 kg load were conducted for final wear by CW3-1 wear machine. The specimen was cleaned with an ultrasonic unit for 3 min followed with drying procedure. After measurement of weight loss and the density of specimens, the specimens were kept for measurement of surface hardness. Surface hardness was measured using a micro-hardness tester with a Vickers diamond indenter after polishing. Three specimens of each material were observed by scanning electron microscopy (SEM) after the abrasion to evaluate the morphology of the surface. Data were analyzed using one-way analysis of variance (ANOVA), followed by Tukey HSD test (α =.05). Results: Z250 performed the least volume wear loss (41.1 ± 2.1 mm3), as well as the hardest value (102.7 ± 2.9 HV). There was no significant difference with the volume wear loss (p = 1.000) and surface hardness (p = 0.874) of HM and TNC. SEM images of nanohybrid filled HM and TNC represented smoother surface compared with other types of resin composites. Conclusions: Microhybrid Z250 showed the highest wear resistance and surface hardness, nanofilled and nanohybrid resin composites may still face the insufficient of wear and surface hardness quality. [ABSTRACT FROM AUTHOR]

Degradation of industrial machinery through wear can be mitigated with the deposition of protective coatings to reduce maintenance costs and prolong their service lifespans. Electroless nickel-based composite coatings is one possible method used to provide this protection. The addition of Tribaloy (CoMoCrSi alloy) particles has been found to produce composite coatings with high toughness. In this work, electroless Ni-P-Tribaloy composite coatings were plated on AISI 1018 steel substrates and subjected to low-stress abrasion tests following ASTM G65 standards to investigate the abrasion of the coating. The test was performed at 10 revolution increments, with a 45 N applied load, until coating failure was observed and the measured abrasion was reported as volume loss. The two Ni-P-Tribaloy coating samples lasted for 90 and 100 revolutions, exhibiting a wear rate of 0.170 mm3 per revolution, compared to 0.135 mm3 per revolution for the Ni-P coatings. The abrasive wear mechanism in the Ni-P-Tribaloy coating was found to be plowing of the matrix around the Tribaloy particles, followed by the removal of the particles once they are protruding, which subsequently contributes to the three-body wear of the coating. The particle removal was accelerated at the coating particle-matrix interface. It is concluded that the size of the Tribaloy is a major factor, and we recommend that further studies be carried out using finer particles to improve the wear resistance of the Ni-P-Tribaloy coating. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of Fused Filament Fabrication (FFF) layer generation strategies on abrasive wear resistance and compare the material loss of PEI (polyetherimide) plastic specimens based on different specimen building strategies. The study also compares a newly proposed path generation strategy (parallel paths in layers with 0.25 mm displacement of alternate layers) with samples from a previous study where samples were printed without displacement of alternate layers, i.e., layers stacked perpendicularly to each other. The primary focus was on the weight loss due to abrasive wear before and after the test. The tests were conducted on a tribometer constructed according to ASTM G65/16 standards using dry sand. Two printing directions were examined: X (longitudinal) and Z (portrait) orientations. For X construction, three orientations of deposition path generation were utilized, resulting in three samples for each orientation (nine samples in total for X construction). The same approach was applied to Z construction, resulting in another nine samples. In total, 18 samples were produced and tested. The deposited infill path width was 0.5 mm, and the layer thickness used in printing was 0.254 mm. Garnet abrasive Fe3Al2(SiO4)3 was employed in this test. Analysis of the experimental data revealed a relationship between the construction method (X and Z orientations) and the variation in different orientations (1X–3X and 1Z–3Z). The research results can be categorized as overall and partial. The overall results indicate poorer wear resistance for 1X–3X and 1Z–3Z specimens, while the partial results illustrate the findings within each individual specimen. [ABSTRACT FROM AUTHOR]

Recently, high-Cr multicomponent white cast iron after quenching is known to have superior abrasive-wear resistance. However, this material is prone to cracking due to the precipitation of very hard carbides resulting in very limited application. However, the cracking tendency might be reduced by appropriate tempering temperature. Therefore, the three-body abrasive-wear resistance of 18 wt.% and 27 wt.% Cr based on 3 wt.% Mo, W, V, and Co with different temperatures of tempering was studied. These are abbreviated as 18Cr MCCI and 27Cr MCCI. The tempering temperature range was 653–813 K with an interval of 20 K after the quenching process. The quenched specimens were used as comparison materials, and three tempered specimens were selected. Thus, there are quenched (Q), quenched-tempered at low temperature (TLT), quenched-tempered at medium temperature (TMT), and quenched-tempered at high temperature (THT) specimens. From the results, it can be known that the wear resistance of the material decreases as Cr percentage and tempering temperature increase. Therefore, the 18Cr MCCI Q has better wear performance than specimens of other conditions. Yet, different results occur in the group of 27Cr MCCI. The material is more wear-resistant after tempering despite the lower hardness of the material. This might be owing to the higher fracture toughness of the M7C3 carbide, which is higher after the tempering process compared with quenching only. Therefore, it can be said that it is important to maintain the hardness of the material to achieve better wear resistance. However, in materials containing large M7C3 carbides, the fracture toughness of carbides should also be considered. [ABSTRACT FROM AUTHOR]

An important problem of modern materials science is to increase the strength and wear resistance of tools and various machine parts. Boriding is one of the promising methods for increasing the surface hardness and wear resistance, resistance to oxidation and corrosion of machine building parts. In this work, boride coatings were obtained using plasma doping technology. It has been established that with an increase in current strength from 120 A to 160 A, the microstructure changes from hypereutectic to hypoeutectic. The maximum hardness was recorded on the sample surface with a current of 120 A and is 1519 HV. After the sliding friction test, it was noted that the boride coating at a current of 120 A has the highest wear resistance. [ABSTRACT FROM AUTHOR]

The subject of the work are modern composite materials with increased wear resistance intended for elements of machines operating in difficult conditions in the construction and mining industries. The study determined the effect of zone reinforcement of GX120Mn13 cast steel with macroparticles (Al2O3 + ZrO2) on the corrosion resistance and abrasion wear of the composite thus obtained. SEM studies have shown that at interface between two phases, and more precisely on the surface of particles (Al2O3 + ZrO2) a durable diffusion layers are formed. During the corrosion tests, no significant differences were found between the obtained parameters defining the corrosion processes of GX120Mn13 cast steel and GX120Mn13 with particles (Al2O3 + ZrO2) composite. No intergranular corrosion was observed in the matrix of the composite material, nor traces of pitting corrosion at both phases interface. This is very important in terms of tested material’s service life. Reinforcement of cast steel with particles (Al2O3 + ZrO2) resulted in a very significant improvement in the abrasion resistance of the composite – by about 70%. After corrosion tests, both materials were subjected to further operational investigations. These examinations consisted in determining the impact of corrosion processes on the durability of the composite in terms of abrasion. The obtained results indicate that corrosion processes did not significantly deteriorate the wear resistance of both the cast steel and the composite. [ABSTRACT FROM AUTHOR]

The development of accelerated test methods can significantly reduce the time required to create reliable equipment. A laboratory setup has been created for the wear testing of samples made from various materials while in motion within an abrasive mass. This method was used to simultaneously evaluate the wear resistance of different materials (steel St. 3, steel 40Kh, steel 45, steel 65G) under identical wear conditions. The dependence of the relative wear resistance of the samples on the rotor speed of the equipment was determined. To assess the influence of regime parameters on material wear, studies were conducted using a centrifugal mill. The wear of the working surface of the mill's accelerating elements occurs due to the material sliding over the blades. Single-factor studies were carried out to determine the intervals and levels of factor variation, and the experiment plan matrix 33 was implemented. Mathematical wear models were derived for the flat radial accelerating elements of the centrifugal mill, all made from steel grades with different hardness levels. Graphical analysis of the mathematical models is presented in the figures. The rotor speed was found to have the greatest influence on the wear intensity of the accelerating elements (blades), followed by the diameter of the initial particles and the grinder's performance. [ABSTRACT FROM AUTHOR]

Rare earth elements have been widely utilized in material manufacturing to enhance properties in various ways. In order to obtain the WC-10Co4Cr coating with uniform distribution of rare earths, CeO2-modified powder was prepared by mixing 1 wt.% nano-sized CeO2 during the initial ball-milling of the powder fabrication process. Bare and CeO2-modified WC-10Co4Cr coatings were deposited via high velocity oxygen fuel spraying to investigate the impact of CeO2 modification on the coating's microstructure, mechanical properties and abrasive wear performance. The results show that the addition of CeO2 increased the interface energy, inhibiting the formation of the Co3W3C phase during the powder sintering process, as well as the W2C phase and CoCr alloy during the high-velocity oxy-fuel (HVOF) process. This led to a significantly decreased porosity and higher concentration of undissolved Cr-rich areas. The microhardness and fracture toughness of the CeO2-modified coating were 1230 HV0.3 and 5.77 MPam1/2, respectively. The abrasive wear resistance of the CeO2-modified coating was only 70.9% of that of the unmodified coating. Due to the weak cohesive strength between WC and Cr, Cr-rich areas were preferentially removed, resulting in an increased wear rate in the CeO2-modified coating. [ABSTRACT FROM AUTHOR]

Since it is well known in the literature that transition metals can form extremely hard carbides and effectively strengthen a material's matrix, recently, some of them, such as V, Nb, Cr, Mo, and W, have been simultaneously added to cast iron. In addition, it is common to add Co to cast iron to strengthen the material's matrix. However, the wear resistance of cast iron can also be considerably affected by the addition of C, which is rarely discussed in the literature by the experts. Therefore, the effect of C content (1.0; 1.5; 2.0 wt.%) on the abrasive wear behavior of 5 wt.% V/Nb, Cr, Mo, W, and Co alloys was investigated in this study. An evaluation was conducted using a rubber wheel abrasion testing machine in accordance with ASTM G65 with silica sand (1100 HV; 300 μm) as abrasive particles. The results show that plural carbides (MC, M2C, and M7C3) precipitated on the microstructure of the material, which is not unlike the behavior of other types of carbides as the quantity of C increases. The hardness and wear resistance properties of 5V-5Cr-5Mo-5W-5Co-Fe and 5Nb-5Cr-5Mo-5W-5Co-Fe multicomponent cast alloys increased as the quantity of C increased. However, we observed no significant difference in the hardness between the two materials with the same C additions, while 5Nb presented better wear resistance properties compared to the 5V sample due to the larger size of NbC compared to VC. Therefore, it can be determined that, in this study, the size of the carbide plays a more important role than its volume fraction and hardness. [ABSTRACT FROM AUTHOR]

Steels are commonly used in high-performance demanding applications due to their favourable mechanical properties. Various surface engineering techniques have been developed for steels, among which chromizing is an affordable high-throughput case-hardenig process for improved surface hardness and wear resistance while retaining the substrate ductility and toughness. In this work, tribological testing along with nano- and micro-indentation and morphological and composional characterisation were used to understand the effects of the chromizing process on the AISI 1095 carbon steel, 52100 bearing steel and A2, D2 and M2 tool steels. The results of this study demonstrate that the chromizing treatment of low-cost 1095 and 52100 steels significantly improves their wear and hardness properties to a level comparable to the more costly tool steels. While chromizing also increased the hardness of the tool steels, it had little improvement on the wear resistance for the D2 and M2 tool steels. [ABSTRACT FROM AUTHOR]

The hardfacings reinforced by recycled (cermet inserts of machining tools) WC-Co composite particles applied by manual arc welding can be used for protection against abrasive and erosive wear. Two categories of coatings were analyzed: with and without thermal treatment (local remelting). The hardfacings were tested under abrasive (low and medium stress) and erosive (high stress) conditions. In elevated temperature erosive conditions, coatings without heat treatment have up to two times higher wear resistance than reference material. Under low-stress conditions, coatings with the finest reinforcing particle size (180–355 µm) treated with local remelting demonstrated more than 10 times higher wear resistance than reference material. The optimal reinforcement size selection depends on the application conditions (low, average, or high stress). In most test conditions, the local remelting did not provide additional improvement. A scanning electron microscope was used for the characterization of wear mechanisms. The relation between mechanical properties and wear rates was found only for some conditions. [ABSTRACT FROM AUTHOR]

Different Al–4Cu–1.5Mg/WC composites were synthesized through powder metallurgy to establish the effect of WC particle addition on the abrasive wear behavior of an Al–4Cu–1.5Mg (wt. %) alloy. The wear tests were performed using a pin-on-disc tribometer at room temperature in dry conditions using SiC abrasive sandpaper as a counterbody and tribometer of linear configuration. The results showed that WC additions increase the hardness of the Al–4Cu–1.5Mg alloy due to the strengthening effect of particle dispersion in the aluminum matrix, which generates an improvement in the wear resistance of the composites by preventing direct contact of the sample with the counterbody, in turn delaying the plastic deformation phenomena responsible for the degradation sequence. In addition, the dominant wear mechanism was abrasive wear, and the increased friction coefficient did not bring a rapid wear rate, which was related to the enhanced deformation resistance due to the high hardness. [ABSTRACT FROM AUTHOR]

Abrasive wear behavior of high-pressure high-velocity oxygen fuel (HP-HVOF) and wire arc spray (WAS) iron-based coatings were compared. Microstructural analysis of the coatings was carried out by scanning electron microscopy and energy dispersive spectroscopy. X-ray diffraction was also used to characterize the microstructures of the coatings. A PANalytical X'Pert PRO diffractometer using a Cu-Ka radiation source was utilized. The microhardness, porosity, and abrasive wear resistance of the produced coatings were compared. ASTM G65 standard was applied for the coatings' abrasive wear assessment using a dry sand rubber wheel abrasion test rig. The HVOF iron-based coatings showed amorphous structures, whereas the wire arc spray technique yielded polycrystalline coatings. The results show higher resistance to abrasive wear for the HVOF coatings in comparison with WAS coatings justified by the higher microhardness, higher amorphous fractions, and lower porosity induced by the process. The morphologies of the worn surfaces of both coatings demonstrated that a combination of micro-plowing and micro-cutting mechanisms has conducted the whole wear process. [ABSTRACT FROM AUTHOR]

In the current practice of applying carbide-based coatings by thermal spraying, the starting material usually contains a metal binder. However, it is important to study the possibility of spraying binder-free carbides, since the metal components usually reduce the operating temperature and corrosion resistance of cermet coatings. In this work, a powder of chromium carbide, Cr3C2, was sprayed using a CCDS2000 detonation gun. Acetylene–oxygen mixtures C2H2 + kO2 with k varying from 0.8 to 3.0 were used as an energetic material. Due to chemical reactions between Cr3C2 and the detonation products, the coatings were of composite nature (multi-phase materials) with a composition depending on k. At k values in the range from 0.8 to 1.1, along with Cr3C2, the coatings contained chromium carbonitride Cr3N0.4C1.6. In the k range from 1.3 to 2.0, Cr7C3 and Cr were the main components of the coatings. As k was increased to 3.0, along with Cr7C3 and Cr, the CrO and Cr2O3 oxides formed in the coatings. The mechanical properties and wear resistance of the coatings were found to depend on their phase compositions. Coatings produced by detonation spraying of Cr3C2 powder may be useful for increasing the corrosion resistance of machine parts to mineral acids and high-temperature oxidation resistance. [ABSTRACT FROM AUTHOR]

The study examines the performance of ZA27 alloy reinforced with in-situ TiC under high-stress abrasive wear conditions. The ZA27 + 10 wt% TiC composite demonstrates superior wear resistance among all the materials tested. Response surface analysis revealed that increasing the applied load reduces the wear resistance of the specimens. Analysis of worn-out surfaces revealed mild grooves at low loads and deeper grooves at higher loads. The removal of material is mainly caused by ploughing and cutting actions from abrasive surfaces. Machine Learning models were employed to forecast wear rate, coefficient of friction, and temperature. The MLP model excelled, achieving an R² value of 0.88 during testing. Furthermore, feature importance analysis revealed that reinforcement wt% has the maximum influence in predicting the wear rate. [Display omitted] [ABSTRACT FROM AUTHOR]

The tribological properties of a PR-NKh17SR4 coating with added boron carbide applied by detonation spraying are studied. Indentation tests show that the coating hardness may be 65 HRC. Wear tests using the TR-471-400 Air Jet Erosion Testing Machine show that metal–ceramic coatings are highly resistant to abrasive wear. [ABSTRACT FROM AUTHOR]

Objective: Wear and surface hardness of resin composites are of relevance from the clinical standpoint. With the incorporation of novel filler system, more studies need to be performed to investigate newly marketed resin composites. The objective of this study was to investigate the abrasive wear and surface hardness of dental restorative with different filler types. Methods: Nanohybrid filled Harmonize (HM) and Tetric N-Ceram (TNC), microhybrid filled Filtek Z250 (Z250), nanofilled Filtek Z350 (Z350) were included in the study. Twelve cylindrical resin composites specimens with 10 mm in diameter and 6 mm in thickness were prepared for abrasive wear test. Eight hundred cycles under 17 kg load were conducted for final wear by CW3-1 wear machine. The specimen was cleaned with an ultrasonic unit for 3 min followed with drying procedure. After measurement of weight loss and the density of specimens, the specimens were kept for measurement of surface hardness. Surface hardness was measured using a micro-hardness tester with a Vickers diamond indenter after polishing. Three specimens of each material were observed by scanning electron microscopy (SEM) after the abrasion to evaluate the morphology of the surface. Data were analyzed using one-way analysis of variance (ANOVA), followed by Tukey HSD test (α = .05). Results: Z250 performed the least volume wear loss (41.1 ± 2.1 mm3), as well as the hardest value (102.7 ± 2.9 HV). There was no significant difference with the volume wear loss (p = 1.000) and surface hardness (p = 0.874) of HM and TNC. SEM images of nanohybrid filled HM and TNC represented smoother surface compared with other types of resin composites. Conclusions: Microhybrid Z250 showed the highest wear resistance and surface hardness, nanofilled and nanohybrid resin composites may still face the insufficient of wear and surface hardness quality. [ABSTRACT FROM AUTHOR]

The development of a technology that increases the service life of valve seats in CNG/LNG-powered vehicles requires the appropriate selection of material and the technology of its application. Commercially used valve seat materials show accelerated wear under operating conditions, especially in natural gas vehicle engines. The authors developed a new material concept and a new technological concept for the protection of the valve seat in CNG/LNG-powered vehicles. This article aims to present the first stage of tribological research. Two materials were used in the research: Stellite 6 alloy and Fe3Al intermetal. A commonly used material for valve seats of combustion engines is Stellite 6. The Fe3Al is the new proposed material coating for the protection of the valve seats of internal combustion engines. This article compares the abrasive wear resistance of these materials. The abrasion tests were performed on a T-11 pin-on-disc tester, and the counter-sample was steel S235JR. The test conditions were similar to those prevailing during the operation of the valves in the head of the internal combustion engine, without the influence of temperature. The obtained results indicate that the Fe3Al intermetal is characterized by a lower coefficient of friction and lower wear intensity than Stellite 6. The results confirm that the Fe3Al phase is a prospective material to be used as a protective material on the valve seat of vehicles. [ABSTRACT FROM AUTHOR]

In this investigation, an effort has been made to analyze the abrasive wear characteristics of cotton grass (CG) reinforced epoxy composites through the hand layup technique. The abrasive wear test is conducted on a dry sand abrasion test machine based on ASTM G65; according to this, the specimen is fabricated with a dimension of 76 × 25 mm2. The engineering application for the composites requires that it should have high wear resistance, low water absorption, and robust strength. Mechanical properties such as tensile strength, hardness, and impact energy are experimentally investigated and optimized and the optimum results are obtained at 9 wt% of CG contents with magnitude of tensile strength of 45.81 MPa, hardness of 34.17 Hv, and impact energy of 2.2 J. The multiple responses of composites are analyzed using the Gray–Taguchi method and optimal factors settings to improve multiple responses, i.e., abrasive wear rate, water absorption, tensile strength, hardness, and impact energy. The results showed that the most critical factor influencing the properties of composites is CG content (9 wt%), accompanied by sliding velocity (96 m/s), normal load (15 N), and sliding distance (60 m). Scanning electron microscopy is used to analyze the composites' worn surfaces to investigate the potential wear mechanism. [ABSTRACT FROM AUTHOR]

Fe-based amorphous coatings have been widely used for various industrial applications due to some excellent characteristics such as high hardness, high strength and high corrosion resistance. However, the poor oxidation resistance greatly limits their application in the field of high-temperature friction and wear. Compared with a Fe-based amorphous coating, a Mo-based amorphous coating is expected to have superior anti-wear performance at elevated temperatures. In this study, Mo- and Fe-based amorphous coatings were deposited by the supersonic atmospheric plasma spraying (SAPS) method. The microstructure and sliding wear behavior of the coatings were comparatively studied. It was found that the wear resistance of the Mo-based amorphous coating was higher than that of the Fe-based amorphous coating although the hardness of the former was a little lower than that of the latter. As the temperature increased to 250 °C, the weak bonding of the inter-splat interface and the formation of hard α-Fe2O3 debris aggravated the three-body abrasive wear and therefore worsened the tribological responses of the coatings. With the increase of temperature, the wear mechanism of the Mo- and the Fe-based amorphous coatings gradually transformed from dominate fatigue wear, with abrasive wear as a secondary mechanism, to dominate abrasive wear, accompanied by oxidation wear. [ABSTRACT FROM AUTHOR]

The effects of attapulgite (ATP) addition (0, 1, 3, 5 and 7 wt %) on the microstructure, chemical composition, thermal stability, physical properties, mechanical properties, water absorption and abrasive wear resistance of walnut shell (WS) filled polyvinyl chloride (PVC) composites were studied. ATP was blended with WS powder, and the WS/ATP/PVC composites were prepared by melt blending extrusion using a single screw extruder. The performance test results of the composites showed that, properties of the composites were improved after the addition of ATP when compared to the composites without ATP, although the chemical structure of the composites did not change significantly. The composites with 3% ATP have the best thermal stability and wear resistance, as well as the lowest water absorption. The tensile strength, bending strength, hardness and density increased by 31%, 16%, 10% and 1% respectively. However, the composite has the highest impact strength after adding 1% ATP, which was 11% higher than without ATP. The results indicate that ATP has the potential to improve the characteristics of biomass composites in a simpler and more environmentally friendly method. [ABSTRACT FROM AUTHOR]