Search

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]

Chemical strengthening of glass represents a standard technology for fabricating damage‐resistant protective covers. Still, little attention has been paid to modifications in the tribological properties of ion‐exchanged glass surfaces. This work reports on scratch testing of a chemically strengthened alkali‐borosilicate thin glass. Diffusive Na+/K+‐ion exchange produces a residual surface compressive layer with compressive stress of 200–340 MPa and layers depths between 16 and 50 µm, depending on exchange temperature and treatment time. This leads to notable changes in the surface mechanical properties, such as an increase in surface Young's modulus, indentation, and scratch hardness. Surprisingly, the Na+/K+‐ion exchange is shifting the onsets of scratch‐induced microcracking and microcracking to lower normal loads. The accelerated buildup of lateral indentation stress in glasses with high scratch hardness was found to be responsible for the lower threshold loads of microcracking and abrasive wear in chemically strengthened alkali‐borosilicate thin glass. [ABSTRACT FROM AUTHOR]

Abstract This study delves into optimizing nanoparticle attributes to enhance the anti-wear performance of nano-lubricants, specifically exploring the influence of nanoparticle material hardness and concentration. Investigating the impact of contamination-induced abrasive wear in lubricants and the subsequent enhancement of anti-wear properties through nanoparticle integration into base oil, the research focuses on, CaCO3, TiO2, and Al2O3 materials representing varied hardness levels. Using ASTM D4172 standards, the study examines the wear resistance of base oil infused with these nanoparticles. Employing a response surface methodology model based on experimental data, the criticality of the interaction between nanoparticle material hardness and concentration in determining wear effects is revealed. Analysis through atomic force microscopy and energy dispersive spectrometry aids in comprehending alterations in wear mechanisms. The research highlights the nuanced relationship between nanoparticle material hardness and concentration in shaping wear behavior within lubricants. Softer materials, like CaCO3, demand higher concentrations for comparable wear reduction as observed with lower concentrations of harder materials, such as Al2O3. Conversely, higher concentrations of harder materials can exacerbate wear, as confirmed by EDS analysis and surface topography studies. This study underscores the importance of nanoparticle material hardness and concentration interaction in determining the efficacy of nanoparticles as anti-wear agents in lubricants. It emphasizes the need to optimize both factors for enhanced anti-wear properties in nanoparticle-based nano-lubricants, offering insights crucial for their application in practical scenarios.

A wood is a heterogeneous material and its elements adversely affect the process of its processing. This also significantly affects the service life of tools during its processing. The aim of the contribution was, based on laboratory tests, to assess the suitability of the application of the selected coating on the chopping knife. After the basic analysis of the chopping knife, the CROSAL+ (AlCrN) coating was designed, which is an improved variant of the successfully used first generation CROSAL coating. In the experiment, samples from two knives made of tool steel X48CrMoV8-1-1 were analyzed. One sample was uncoated and the other coated. Based on the results of laboratory analyzes and tests, namely basic macroscopic and microscopic analysis of samples from tools, with semi-quantitative EDX analysis to determine the presence and content of individual chemical elements on the base material - substrate. Furthermore, the samples were tested for resistance to abrasive wear according to GOST 23.208-79. Relative resistance to abrasive wear ψabr was assessed. and hardness coefficient KT. HV and HRC hardness measurements were also carried out to determine the difference in hardness between uncoated and coated knife samples. In conclusion, it can be concluded that from the analysis and results of the measurements, the given coating for the process of processing wood by chopping can ensure the extension of the life of the tool and ensure the sufficient quality of the produced chips. [ABSTRACT FROM AUTHOR]

The present study is directed to the problem of hardfacing and restoration of worn industrial equipment. Wear tests were carried out using especially built rig which reproduces working conditions of machinery applied in cement plants. The results of tribological tests on 20 Fe- and Ni-base hardfacings are presented. The effect of hardfacing hardness and chemical composition was evaluated. It was found in SEM examinations that matrix was removed from the zone adjacent to carbides which made them liable to cracking and digging out. The mechanism of matrix removal depended on its hardness and include microcutting and low cycle fatigue. Ni-based hardfacings outperformed Fe-based coatings. The abrasion resistance of the best Ni-base coating, the Stelcar 6 was 38.7 times higher than that of S235JR steel. Eutectics in Ni-base coatings disturb motion of abrasive grains and force them to rotate instead of sliding over hardfacing surface. Ni-based coatings can be considered in hardfacing or reclamation of numerous industrial components applied in cement plants. [ABSTRACT FROM AUTHOR]

The possibility of introduction of titanium carbide into a weldpool is studied. Titanium carbide forms in the metal deposit structure due to proper in situ alloying. However, the in situ technology is rather complicated because of difficulties associated with the impossibility of controlling the factors predetermining the alloying element redistribution between the carbide phase and the matrix. Therefore, attention is frequently given to the introduction of titanium carbide in the finished form (ex situ technology). Titanium carbide particles can be applied as a reinforcing phase in the preparation of wear-resistant coatings using this technology. Titanium carbide is not thermodynamically prone to decomposition and interaction with the chemical elements in the Fe–Ti–C system, demonstrating its high stability. However, experimental studies show that titanium carbide undergoes cracking and dissolution in a weldpool. This process is accompanied by the saturation of the metal with titanium and an increase in its hardness. [ABSTRACT FROM AUTHOR]

Copyright of Listy Cukrovarnicke a Reparske is the property of VUC Praha a.s. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Fe-B alloy is a candidate for a low-cost wear-resistant material but shows very low fracture toughness. To improve the toughness of Fe-B alloys, for this study we attempted to break the continuous network of eutectic Fe2B via K2SO4 addition and heat treatment, so that the Fe2B particles transform to be more spherical. The microstructure, mechanical properties, and two-body and three-body abrasive wear behaviors of the alloys modified with various K2SO4 additions were systemically investigated. The results show that the heat-treated alloys mainly consist of martensite and M2B (M = Cr, Mn, Fe, etc.). With the addition of K2SO4, a new phase α-MnS forms in the alloy, and the circularity value of M2B increases from 0.13 to 0.44. The impact toughness of alloy increases from 6.09 J/cm2 to 14.72 J/cm2 with an increment of 142%, although the Rockwell hardness does not show obvious change. Meanwhile, the two-body wear weight loss of alloys exhibits a "decrease and then increase" trend with increasing K2SO4 addition, while the three-body wear weight loss decreases first and then remains unchanged. The different wear behaviors were investigated and discussed. [ABSTRACT FROM AUTHOR]

High-performance complex gear cutters and high-temperature bearings are just some of the applications where high-speed steels (HSSs) shine as a preferred material choice owing to their high hardness and outstanding wear resistance. In this work, the effects of sintering temperature on the microstructure and mechanical properties of S390 HSS prepared via spark plasma sintering (SPS) were investigated with a range of sintering temperatures from 930°C to 1,090°C, a uniaxial pressure of 50 MPa, and a holding time of 5 min. The results demonstrated that the improvements in density, hardness, red hardness, and three-point bending strength were confirmed as the sintering temperature increased from 930°C to 1,090°C. Temperature-induced microstructure evolutions were assessed for their contribution to property enhancement, such as powders with varying dimensions and carbides with diverse morphology and diameter. The specimen with the best comprehensive mechanical properties (67.1 HRC and 1,196.67 MPa) was prepared at 1,050°C via SPS. The wear coefficients decreased as the sintering temperature increased, and the observation results of worn surfaces of test pins confirmed that abrasive wear and oxidation wear dominated the wear experiments. Furthermore, the wear mechanism of dense and porous SPS HSS was illustrated and analyzed in terms of the debris and trapped carbides.

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]

Cast austenitic chromium-nickel steel is commonly used for the manufacture of machine parts and components, which are exposed to the attack of corrosive media and abrasive wear during operation. The most commonly used grades include GX2CrNi18-9 and X10CrNi18-8 as well as GX2CrNiMo17-12-2 and X6CrNiMoNb17-12-2. To improve the abrasion resistance of cast chromium-nickel steel, primary niobium carbides were produced in the metallurgical process by increasing the carbon content and adding Fe-Nb. The microstructure of the obtained test castings consisted of an austenitic matrix and primary niobium carbides evenly distributed in this matrix. The measured hardness of the samples after heat treatment ranged from 215 to 240 HV and was higher by about 60 units than the hardness of the reference cast GX10CrNi18-9 steel, which had a hardness of about 180 HV. Compared to the reference cast steel, the abrasive wear resistance of the tested cast chromium-nickel steel (measured in Miller test) with contents of 4.4 and 5.4 wt% Nb increased only slightly, i.e., by 5% for the lower niobium content and 11% for the higher niobium content. Compared to ordinary cast GX10CrNi18-9 steel, the addition of 9.2 wt% Nb reduced the abrasive wear by almost 2.5 times. [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]

Copyright of Listy Cukrovarnicke a Reparske is the property of VUC Praha a.s. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It has been evaluated the relationship between the microstructure and three-body abrasive wear behavior of high-chromium (18 and 27 mass % Cr) based (3 mass % each of V, Mo, W, and Co) multicomponent white cast iron materials (high-Cr MWCIs). It was also compared to MWCI to determine the service life of the materials. The results indicate that the microstructure of the material is composed of mainly martensite matrix and different types of precipitated carbides. The wear resistances of both the high-Cr MWCIs are higher than MWCI owing to the higher hardness (4–18% increment in hardness), although they contain fewer carbide types. The carbide volume fraction of high-Cr MWCI increases with increase in the Cr content, but the hardness decreases, leading to a reduction in wear resistance. This is because the transition metal significantly consumes C atoms to form more eutectic carbides during solidification, which is exacerbated by the depletion of C in the matrix during heat treatment to form coarser secondary carbides. This means that increasing the addition of Cr does not always lead to an increase in the hardness or wear resistance of the material. In addition, the wear resistance of 27Cr MWCI after tempering (wear rate: 8.80 × 10−5 g/m) is higher than that after quenching (wear rate: 9.25 × 10−5 g/m) owing to the increase in the fracture toughness of M7C3 carbide. This is contrary to the case of 18Cr-MWCI; the wear resistance after tempering (wear rate: 5.29 × 10−5 g/m) is worse than that after quenching (wear rate: 5.11 × 10−5 g/m) owing to the reduction in hardness as a stress-relieving effect. [ABSTRACT FROM AUTHOR]

Increasing demand for sustainable approaches to mining and raw material extraction, has prompted the need to explore advanced methods of surface modification for structural steels used in the extractive industry. The technology of powder plasma transferred arc welding (PPTAW), was used in this study as a surface modification technique to improve upon the abrasive wear resistance of structural steel grade EN S355. PPTAW process parameters, namely, plasma transferred arc (PTA) current and plasma gas flow rate (PGFR), were varied, and the effects of the variation were studied and used as criteria for selecting optimum conditions for further studies and parametric reproducibility. Two metal matrix composite (MMC) powders were used in the process, having compositions of Ni-Si-B+60 wt%WC (PG) and Ni-Cr-Si-B+45 wt%WC (PE). Microstructural observation under a scanning electron microscope (SEM) revealed a dendritic, multi-directional microstructure consisting of partially dissolved primary tungsten carbide particles and secondary tungsten carbide precipitates within the MMC solid solution. The hardness of the surface layers was higher than that of a reference AR400 steel by more than 263 HV. Final surface layers obtained from the MMC powders had abrasive wear resistance up to 5.7 times that of abrasion-resistant reference AR400 steel. Alloying the MMC matrix with chromium increased the hardness by 29.4%. Under the same process conditions, MMC powder with 60 wt% WC reinforcement had better abrasive wear resistance by up to 45.8% more than the MMC powder with 45 wt% WC. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of the influence of the heat treatment state on the abrasive wear of the AW7075 aluminium alloy. To determine the hardening state, the material hardness was measured. It was found that hardness is not the only factor that influences this type of wear. For this reason, the influence of the emerging microstructure is also analysed in the considerations. After tribological tests, microscopic observations of surface features were carried out to determine the dominant mechanisms of surface damage. The results were extended by the hardness distribution carried out on the cross-section. There were no changes in hardness that could be related to either strain hardening or structural changes caused by friction. [ABSTRACT FROM AUTHOR]

Based on an empirical–mathematical model and on detailed quantitative SEM inspections, the distribution parameters of a two-parameter Weibull transition model are computed for three typical polymer materials for organic offshore coatings. The model links a plastic–elastic transition parameter to applied normal forces. The scale parameter depends on the polymer hardness and is particularly high for the elastically responding epoxy. [ABSTRACT FROM AUTHOR]

The possibilities of introducing silicon carbides into a weldpool melt are studied. Silicon carbide powders are introduced into the weldpool melt providing carbide shielding from a direct arc action. Reaching the weldpool melt, silicon carbide is found to decompose completely, increasing the silicon and carbon contents and, hence, the hardness. When decomposing, silicon carbide is shown to act as a deoxidizer. [ABSTRACT FROM AUTHOR]

The effect of micro-alloying Sn (0.08 wt.%) on dry sliding abrasive wear behaviour of cast Al-Mg-Si alloy was investigated. Additionally, microstructure, hardness, and their impact on wear resistance were also investigated. It was observed that Sn contributes to the hardness and accelerates the age-hardening response of the Al-Mg-Si alloy. Sn addition also favours the formation of script-like Al(Fe, Mn)Si phase and increases the amount of Mg2Si precipitate. SEM investigation of worn surfaces reveals a similar abrasive wear mechanism in both the alloys which were micro-cracking, ploughing, and delamination. The study also reveals that improving the hardness by micro-alloying 0.08 wt.% Sn can prevent mass loss and marginally improves the wear resistance of the Al-Mg-Si. [ABSTRACT FROM AUTHOR]

It has been evaluated the relationship between the microstructure and three-body abrasive wear behavior of high-chromium (18 and 27 mass % Cr) based (3 mass % each of V, Mo, W, and Co) multicomponent white cast iron materials (high-Cr MWCIs). It was also compared to MWCI to determine the service life of the materials. The results indicate that the microstructure of the material is composed of mainly martensite matrix and different types of precipitated carbides. The wear resistances of both the high-Cr MWCIs are higher than MWCI owing to the higher hardness (4–18% increment in hardness), although they contain fewer carbide types. The carbide volume fraction of high-Cr MWCI increases with increase in the Cr content, but the hardness decreases, leading to a reduction in wear resistance. This is because the transition metal significantly consumes C atoms to form more eutectic carbides during solidification, which is exacerbated by the depletion of C in the matrix during heat treatment to form coarser secondary carbides. This means that increasing the addition of Cr does not always lead to an increase in the hardness or wear resistance of the material. In addition, the wear resistance of 27Cr MWCI after tempering (wear rate: 8.80 × 10−5 g/m) is higher than that after quenching (wear rate: 9.25 × 10−5 g/m) owing to the increase in the fracture toughness of M7C3 carbide. This is contrary to the case of 18Cr-MWCI; the wear resistance after tempering (wear rate: 5.29 × 10−5 g/m) is worse than that after quenching (wear rate: 5.11 × 10−5 g/m) owing to the reduction in hardness as a stress-relieving effect.

We report on surface elasticity, plastic deformation and crack initiation of chemically strengthened soda‐lime silicate and sodium aluminosilicate glasses during lateral indentation and scratch testing. Instrumented indentation using a normal indenter set‐up corroborated previous findings on the effects of chemical strengthening on surface Young's modulus, hardness, and indentation cracking. Using lateral indentation in the elastic‐plastic regime, we find a pronounced increase in the scratch hardness as a result of chemical strengthening, manifest in higher work of deformation required for creating the scratch groove. Thereby, the glass composition is found to play a stronger role than the absolute magnitude of surface compressive stress. Using a blunt conical stylus for instrumented scratch testing reveals three distinct modes of scratch‐induced surface fracture, which occur during scratching or after unloading. Occasional micro‐cracking caused by pre‐existing surface flaws at low scratching load can be completely suppressed through chemical strengthening. The intrinsic defect resistance to microcracking is reduced as a result of ion stuffing, depending on the initial glass composition, whereas the resistance to abrasive yielding is enhanced by several hundred MPa. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive review on surface hardening of ferrous materials using in- situ diffusion of nascent carbon and nitrogen from cyanide-based bio-processed cassava wastes with BaCO3and BaCl2energizers (bio-cyaniding). The review focuses on the research efforts on bio-cyaniding (also known as pack cyaniding) of iron and steel during the last decade. A brief description of the processes is elucidated along with the effects of bio-cyaniding on the microstructure, micro-/nano-hardness and wear properties of the bio-cyanided surfaces. Both intermediate-temperature bio-cyaniding (in-situ diffusion into ferrite) and high-temperature bio- cyaniding (in-situ diffusion into austenite) are also described. The bio-cyaniding hardening technique is compared with competing hardening techniques. It was concluded that the use of bio-cyaniding for the surface hardening of metals provides an alternative technique to the conventional surface hardening processes and offers potential advantages such as relatively low capital cost of the equipment, operating temperature and time.

The article deals with the assessment specific hard facing material with W2C high content - filled welding rod for manual flame hard facing RD 571. Is was applied in two layers on the samples (16MnCr5 steel) of the tool for crushing undesirable advance growths, frequently used in forestry technologies. The tools work in a heterogeneous environment. They are loaded by abrasive impression of wood mass, which are characterized by various hardness. The material loss on the functional parts is significant. The wear degradation of the tool and its subsequent early decommissioning represents economic losses for forest companies. The investigations conducted under laboratory conditions involved hardness measuring HV10 and HRC, wear resistance testing of materials by friction against loosely fixed abrasive parts, with assessment profile and depth of the mark as well as assessment of quality mixing of the layers, microstructure assessment by SEM with EDX analyses. By evaluating the laboratory tests, the conclusions were drawn to determine the suitability or the non-suitability of the selected hardfacing material in service. Whether the material increases the service life of the undesirable crusher tool, will by verified by performing field trials. [ABSTRACT FROM AUTHOR]

Copyright of Listy Cukrovarnicke a Reparske is the property of VUC Praha a.s. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, polypropylene/thermoplastic polyurethane (PP/TPU) blends (weight ratios of 75/25 and 25/75) were produced by melt blending, and a maleic anhydride-grafted polypropylene (PP-g-MA) copolymer was used as a coupling agent. The effect of the concentration of the coupling agent (5–11 phr), TPU concentration (25–75%), normal load (2–4 N) and sliding velocity (60–72 rpm) on the wear properties of the blends were characterized through a pin-on-disc abrasive wear test. A 24 full-factorial experimental design was chosen to screen the significant factors and their interactions influencing the tribological performance of the blends. After the tests, the morphology of the worn surface of the samples was observed using scanning electron microscopy. Shore D hardness tests were also conducted and the relationships between these behaviours were analysed on the basis of the findings. According to the wear test results, the factors that have the greatest effect on the wear rates are as follows: normal load, TPU concentration, sliding velocity and PP-g-MA concentration, respectively. The wear rate of the blends increases by increasing the normal load, TPU concentration and sliding speed, and slightly decreases by increasing the PP-g-MA concentration. As expected, the wear and hardness results showed the apparent superiority of the PP75/TPU25 blends over the PP25/TPU75 blends, because of the higher content of rigid segments in the blends. [ABSTRACT FROM AUTHOR]

A new method of assessing the impact–abrasive resistance of steel permits simulation of the impact–abrasive wear with variation in the magnitude and inclination of the impact force, type of abrasive, and its grain size and rate of consumption. The influence of five carbide-forming elements on the properties of the cast and quenched steel is studied: specifically, attention focuses on the abrasion resistance, impact–abrasive resistance, and hardness of the steel. Optimal steel compositions with abrasion resistance and impact–abrasive resistance greater than that of 35GL steel are identified. [ABSTRACT FROM AUTHOR]

The analysis of possibilities on phase-structural engineering of titanium-based alloys during micro-arc plasma oxidation (MAO) is carried out. The influence of phase-structural states on the tribotechnical properties of the modified surface of the titanium alloy VT3-1 is also considered. It has been established that in order to achieve high functional properties, it is necessary to use electrolytes of complex composition for MAO. The presence in the electrolyte of (NaPO3)6 leads to the formation of anatase with a low hardness (about 3 GPa). The formation of crystallites of rutile and aluminum titanate with the use of alkalinealuminum electrolyte allows to increase hardness significantly (up to 7 GPa). The maximum increase in hardness (up to 12 GPa) is achieved in the coating obtained in alkaline-aluminate-silicate electrolyte. This is due to the formation of crystalline mullite. The friction coefficient of such a material decreases (f < 0.01) and as a result, antifriction properties increase. The results of the work indicate the prospects for using the phase-structural engineering method for MAO-processing to optimize the formation of antifriction coatings on titanium alloys. [ABSTRACT FROM AUTHOR]

Effect of pressure of the reaction gas on the texture, structural stress state and mechanical properties (hardness and resistance to abrasive wear) in vacuum-arc coatings based on Ti-V-Zr-Nb-Hf-Ta nitrides of high entropy alloys were investigated in this work. At a bias potential of – 200V, an increase in nitrogen pressure during deposition from 2.5·10 – 4 to 4.5·10 – 3 Torr leads to an increase in the content of nitrogen atoms in the coating, and the formation of a bittexture state [111] + [311] is established. The formation of a biaxial texture occurs due to the presence in alloys of atoms with very different masses (Ti, V and Hf, Ta). The use of a multi-element composition in a single-phase state with a simple cubic lattice allows to achieve high values of microstrain (up to 1.4 %) with a low deposition pressure. It is determined that the increase of nitrogen pressure during deposition leads to an increase in macrostresses. The highest hardness of 53 GPa is achieved in coatings obtained at a pressure of 2·10 – 3 Torr. It has been established that coatings with high resistance to abrasive wear are found to be: crystallite grain size 12-25 nm, absent of texture (or a low level of texture perfection), and also rather high microstrain in crystallites. [ABSTRACT FROM AUTHOR]

Nylon (N), Glass-filled nylon (GFN) composites and hybrid graphene oxide blended GFN (GO-GFN) nanocomposites plates were prepared by blending and subsequent injection molding process. Mechanical tests were conducted to study the tensile property, flexural property and hardness of nylon, GFN and GO-GFN system. The fabricated plates were subjected to abrasive wear testing in Pin-on-disc tribometer. The pin used is aluminium oxide (Al2O3) ceramic tool. The coefficient of friction, frictional force and loading variations were observed and studied to analyze the susceptibility of nylon, GFN and GO-GFN nanopolymer composites for abrasive wear conditions. This experimental study confirmed the enhancement in the abrasive wear resistance behavior of GO-GFN hybrid nanocomposites. [ABSTRACT FROM AUTHOR]

A technique is developed for evaluating the impact-abrasive resistance of cast specimens, which allows simulating the conditions of impact and abrasive wear when changing the following factors: impact energy, abrasive impact angle, abrasive type, and its consumption and grain size. The complex experiment results for five carbide-promoting elements effect on abrasive (AR), impact and abrasive (IAR), and antifriction (AFR) steel resistance in the cast and hardened states are presented. The possibility of using the new technique for evaluating wear resistance and optimizing the composition of steel operating under impact-abrasive effects is shown. [ABSTRACT FROM AUTHOR]

Cyclic heat treatment of steel samples is considered as a means of increasing their abrasive wear resistance. Cyclic heating of 65Г steel parts to 450°С increases their wear resistance by 40% in comparison with traditional inductive quenching. [ABSTRACT FROM AUTHOR]

During the coal pulverizing, the working parts of the ventilation mill are being worn by the sand particles. For this reason, the working parts are usually protected with materials resistant to wear (hardfaced/thermal sprayed coatings). The aim of this study was to evaluate the tribological performance of four different types of coatings as candidates for wear protection of the mill’s working parts. The coatings were produced by using the filler materials with the following nominal chemical composition: NiFeBSi-WC, NiCrBSiC, FeCrCTiSi, and FeCrNiCSiBMn, and by using the plasma arc welding and flame and electric arc spraying processes. The results showed that Ni-based coatings exhibited higher wear resistance than Fe-based coatings. The highest wear resistance showed coating produced by using the NiFeBSi-WC filler material and plasma transferred arc welding deposition process. The hardness was not the only characteristic that affected the wear resistance. In this context, the wear rate of NiFeBSi-WC coating was not in correlation with its hardness, in contrast to other coatings. The different wear performance of NiFeBSi-WC coating was attributed to the different type and morphological features of the reinforcing particles (WC).

Functionally graded metal matrix composites (MMCs) and homogenous composites (Al/AlN and Al/SiO2-10 wt%) have been fabricated through centrifugal casting and liquid metallurgy route, respectively. The properties of these composites were compared with aluminum alloy. Microstructural characteristics and hardness were studied on the surfaces of functionally graded materials (FGMs), homogenous composites, and unreinforced aluminum alloy using an optical microscope and a Vickers micro hardness tester, respectively. Tensile test was carried out on the outer and inner sections of FGMs and specimens from homogenous composites and alloy utilizing universal testing machines (UTMs). Three-body abrasive wear test was conducted for different loads and speeds to study their effect on the surfaces of composites and alloy using dry abrasion tester. Microstructural and hardness results reveal that the outer surface of aluminum nitride (AlN)-reinforced FGM has a particle-enriched region with the highest hardness. Tensile strength was found higher in both homogenous composites compared to zones of their FGMs. Abrasion wear rate was found increased with increase in load and decreased with increase in speed. The outer surface of AlN-reinforced FGM has higher wear resistance followed by the outer surface of SiO2-reinforced FGM. Scanning Electron Microscopy (SEM) analysis was performed on worn-out surfaces and observed particle-enriched outer surface of Al/AlN FGM with less abrasion. [ABSTRACT FROM AUTHOR]

The tribological behaviors of various microstructures are investigated, but it is mainly focused on wear without fixing hardness and/or chemical composition. Therefore, friction tests between steel pins with different microstructures for similar hardnesses (310 H V –500 H V ) and abrasive papers with different sizes (15 μm-200 μm) under different loads (50N-110 N) are performed. For each hardness, compared to single-phase and multi-phase microstructures, dual-phase microstructures improve the tribological behavior. Among these microstructures, as martensite colonies become coarser and equiaxe, the tribological behavior is enhanced. Moreover, as hardness increases, friction coefficient and wear rate decrease for each microstructure whereas the microstructure effect on the tribological behavior is less pronounced. A transition in friction behavior and wear mechanisms is observed for an optimal particle size (CPS) around 35 μm. [ABSTRACT FROM AUTHOR]

Abstract In the present study, 6 wt% Mo was added into high chromium cast iron (HCCI, 16 wt% Cr), and the effects of heat treatment on microstructure and mechanical properties of the base and alloyed HCCI were investigated. A ledeburite matrix and Mo-rich M 2 C were obtained besides M 7 C 3 in the as-cast alloyed HCCI. During the soaking process of the destabilization treatment, amounts of secondary carbides (M 23 C 6) precipitated out of austenite. Martenstic transformation of matrix occurred in the forced air cooling process. Most of the M 2 C decomposed into bright white fishbone M 6 C and punctate MC. The overall hardness of alloyed HCCI increased due to the presence of Mo-rich carbides and martensite matrix with secondary carbides. Comparing with the destabilized sample, the toughness of the alloyed HCCI improved and the hardness decreased after tempering treatment, and the toughness of the alloyed HCCI increased with the increase of tempering temperature. The abrasive wear resistance of the HCCI improved with the addition of Mo after heat treatment, and the QT500 sample had the optimal wear volume loss. The abrasive wear resistance decreased with the increase of tempering temperature, due to the exsolution of C atoms in the martensitic matrix. Highlights • A ledeburite matrix and Mo-rich M 2 C were obtained with the addition of 6 wt% Mo. • As the carbides are obtained by in situ reaction, the wettability between the carbide and matrix is better. • After a quenching treatment, the M 2 C decomposed into bright white fishbone M 6 C and punctate MC. • The impact toughness of samples enhanced slightly after tempering treated. • Secondary carbides (M 23 C 6) precipitated out during the soaking process of the destabilization. [ABSTRACT FROM AUTHOR]

Microstructural evolution, hardness and abrasive wear resistance of plasma-transferred arc (PTA) multipass Fe-Cr-V-Mo-C coatings deposited using plasma source weaving has been investigated. As shown, the deposited metal contains structurally different as-deposited clad zone and reheated zone. There are reheated zones formed between the coating beads and between microbeads formed due to weaving mode deposition (WPTA). Both types of zones contain eutectic carbide recrystallization and incomplete melting regions. No high-martensite, low wear resistance high-tempered region inherent to standard multipass PTA deposition has been found. The overall wear resistance of the coating has been improved as compared to the PTA version. [ABSTRACT FROM AUTHOR]

Agricultural tools need mechanical properties such as abrasive wear, hardness and toughness. These mechanical properties are achieved by choosing a suitable steel and subsequent heat treatment of the steel. Phases of the microstructure affects the final steel properties. The phase composition in the steel is influenced with the designing of the heat treatment. 25CrMo4 steel was investigated for the production of agricultural tools. The heat treatments ware designed for different cooling conditions. The salt bath was used to cooling as a medium with subsequent cooling on the water or in the air. The FEM method was used to designing the heat treatment conditions. The Johnson-Mehl-Avrami-Kolmogorov equation and the Koistinen-Marburger equations were used to prediction the microstructure phases. The microstructures were verified with experimental measurements. The ASTM G65 method was using for abrasion resistance tests. The results show that this procedure can be used to designing parameters of heat treatment of agricultural tools. [ABSTRACT FROM AUTHOR]