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This study investigated dry sliding wear properties of AZ31 magnesium alloy and B4C-reinforced AZ31 composites containing 5, 10, and 20 wt.% B4C with bimodal sizes under different loadings (10–80 N) at various sliding speeds (0.1–1 m/s) via the pin-on-disc configuration. Microhardness evaluations showed that when the distribution of B4C particles was uniform the hardness of the composites increased by enhancing the reinforcement content. The unreinforced alloy and the composite samples were examined to determine the wear mechanism maps and identify the dominant wear mechanisms in each wear condition and reinforcement content. For this purpose, wear rates and friction coefficients were recorded during the wear tests and worn surfaces were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry analyses. The determined wear mechanisms were abrasion, oxidation, delamination, adhesion, and plastic deformation as a result of thermal softening and melting. The wear evaluations revealed that the composites containing 5 and 10 wt.% B4C had a significantly higher wear resistance in all the conditions. However, 20 wt.% B4C/AZ31 composite had a lower resistance at high sliding speeds (0.5–1 m/s) and high loadings (40–80 N) in comparison with the unreinforced alloy. The highest wear resistance was obtained at high sliding speeds and low loadings with the domination of oxidative wear.

Statement of problem Dental implants undergo various surface treatments. Studies that have characterized their surface and subsurface by using the same methods are scarce. Purpose The purpose of this study is to physically characterize the surface and subsurface of implant systems made of commercially pure (cp) titanium (Ti) grade (gr) 4 and Ti alloy gr 23 and to evaluate whether airborne-particle abrasion and acid etching is an appropriate surface treatment for Ti alloy gr 23. Material and methods Implant groups (n=3) were as follows: TG4AO, cp Ti gr 4, treated with anodic oxidation (3.5×8 mm) (NobelReplace Conical; Nobel Biocare); TG23AE, Ti gr 23 (TiAlV ELI) airborne-particle abraded-and-etched (3.9×8 mm) (V3; MIS); and TG4AE, cp Ti gr 4, airborne-particle abraded and etched (3.3×8 mm) (BL; Institut Straumann AG). Surface roughness, surface topography, and elemental and surface composition were investigated with optical profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The presence and size of Ti hydride (TiH) needles were determined on metallographic sections. Depth profiling was obtained by time-of-flight secondary ion mass spectrometry (ToF-SIMS) to determine possible enrichment of an alloying element at the implant surface. Results The mean arithmetic deviation roughness (Sa), of TG4AO was 0.80 μm. The Sa of TG4AO was 1.22 μm, and the Sa of TG4AO was 1.59 μm. The difference between the groups was significant (P Conclusions The roughness, topography, and composition of the surfaces were different for all implants tested. Airborne-particle abrasion and subsequent etching was an appropriate treatment for Ti gr 23 alloy implants.

This paper presents the investigation of dielectric analysis of degraded stator bars by Polarization and Depolarization Current (PDC) measurement. The stator bars obtained from the 30-year in-service synchronous machine were divided into two groups. The first group was the unmodified stator bars. The second group was the simulated degradation stator bars which were composed of the thermal stress stator bars, conductive tap abrasion stator bars, multiple air cavity stator bars, multiple oil filled stator bars and multiple water filled stator bars. PDC test experiment was performed with the stator bar samples. PDC test results were analyzed in time domain and in frequency domain with the derived parameters i.e. R dc , real and imaginary part of complex capacitance, C ratio, conduction loss factor and polarization loss factor. It was found that PDC shapes obtained from the conductive tape abrasion stator bar and multiple water filled cavity stator bar were clearly different from that of the unmodified stator bar. For other case studies, the derived parameters showed the usefulness in analysis the degraded stator bar characteristics. For example, the increase in the imaginary capacitance and conduction loss factor can be observed from most cases of degraded stator bar test results.

Al2O3 coatings were prepared by atmospheric plasma spraying (APS) and suspension plasma spraying (SPS). The microstructure, phase composition and nano-hardness of the two coatings were tested. Meanwhile, the friction and wear performance of SPS and APS in different environments were systematically studied. The results showed that both coatings exhibited a stable friction state and low wear rate under different environments. The special fine structure and high hardness value of SPS coating made its wear resistance much higher than that of APS coating. Additionally, the wear mechanisms of the two coatings in dry sliding friction were mainly abrasive wear, fatigue wear and adhesive wear. The APS coating had slight abrasion, while the SPS coating exhibited a negative abrasion state, in the seawater environment.

Leucite and zirconia are commonly used in the production of prosthetic dental materials. Leucite presents attractive optical properties but low toughness and wear resistance, which limits its use. Zirconia has much higher toughness, but due to aesthetic reasons and ageing issues, needs to be glass veneered. Chipping of such veneer is usually responsible for the abnormal wear induced on the antagonist teeth. Leucite reinforced with 25% of nano-zirconia is a promising alternative to overcome these issues, allowing the production of dental restorations without veneer. This study aims to investigate if leucite-zirconia composites have suitable optical, mechanical and tribological properties to be used in dental restoration. Samples with different compositions of leucite and/or nano-zirconia were produced by unidirectional compression and characterized concerning density, surface morphology, roughness, hardness, toughness, and translucency. Wear tests were performed in a chewing simulator using human cusps as counterbodies. Tests were also performed in glazed zirconia for comparison. 25% ZrO2 leads to the lowest wear of the tribological pair among the studied systems, except 100% ZrO2. This can be attributed to the toughening effect of zirconia and reduced size of third body particles. Abrasion was the main wear mechanism observed in this pair. In addition, this was the composite that presented the highest translucency.

In brickyard industry, smooth roll crusher is the most critical component in the brick production process. The main damage to the surface of the roll crusher comes from abrasion wear. Grey cast iron with a CE around 4.0 was chosen for the manufacture of these rolls crushers. Castings with various compositions in the basic Class 25 grey cast iron were cast with the combined effects of copper and chromium to study their effects on their castability, mechanical properties and wear. The casting parts were heated to 900 °C and quenched with forced air. Optical metallography, chemical analyses, Brinell hardness and Vickers microhardness, tensile tests and wear tests were used to characterize the ingots cast. All the cast irons made were hypoeutectoid with a microstructure consisting mainly of class A type graphite in a pearlitic matrix. The sensitivity of cast iron to the mass effect has been greatly reduced by appropriate and economical additions of copper and chromium. Normalization treatment, high cooling rate through the eutectoid transformation temperature interval and additions of Cu and Cr promote the formation of a finer and harder pearlite. All these factors contribute to increase the strength and hardness of alloyed hypoeutectic grey cast iron. The results showed that the quenched and tempered alloys had best wear resistance at 400 °C for alloyed grey cast iron (containing 0.62%Mn, 0.37%Cr, 1.21% Cu and 0.12%Mo).

The ceramics machining industry faces several challenges due to the elevated difficulty of cutting hard and brittle products. In this context, polycrystalline diamond (PCD) tools are one of the few materials that can perform this function. However, the development and improvement of such tools are necessary to promote longer durability and cost minimization. This work aimed to investigate the performance of PCD-Ta composites on granite rock machining. The products were prepared using different Ta concentrations and tribologically tested in a pin-on-disc configuration. The overall outcomes indicated that all compositions experienced a Coefficient of Friction (CoF) increase at the beginning of experiments, followed by a values stabilization period (steady-state). Scanning Electron Micrographs (SEM) showed that abrasion was the main wear mechanism of rocks, and some cracks were also observed due to the brittleness of granite. Products with lower Ta quantity also promoted more intense wear on granite discs, resulting from the elevated percentage of hard phase (PCD) on composites. Furthermore, all pins exhibited high integrity and a low binder loss after the tests under the proposed conditions.

In the present study, a fully lamellar Ti6Al4V alloy was severely deformed by high pressure torsion (HPT) process under a pressure of 7.5 GPa up to 10 revolutions. Experimental results revealed that the microhardness of Ti6Al4V was increased remarkably by about ∼ 41% and saturated at about 432 Hv after the HPT process. A relatively uniform bulk nanostructured Ti6Al4V alloy with an average grain size of about 52.7 nm was obtained eventually, and no obvious formation of metastable ω phase was detected by XRD analysis. For the first time, the tribological properties of the HPT processed Ti6Al4V alloy were investigated by a ball-on-disc test at room temperature under a dry condition. It was found that HPT process had a great influence on the friction and wear behaviors of Ti6Al4V alloy. With increasing the number of HPT revolutions, both friction coefficient and specific wear rate were obviously decreased due to the reduction of abrasion and adhesion wears. After being deformed by 10 HPT revolutions, the friction coefficient was reduced from about 0.49 to 0.37, and the specific wear rate was reduced by about 48%. The observations in this study indicated that HPT processed Ti6Al4V alloys had good potential in structural applications owing to their greatly improved mechanical and tribological properties.

Ballast degradation through attrition and breakage during operations affects the structural performance of the railway track system. In an attempt to study railway ballast degradation changes due to train cyclic loading at micro-scale. This study quantified and compared the changes that occur on ballast particles due to ballast degradation using LAA test and image analysis techniques. TB/T 2328.14-2008 gradation use by china railways was adopted. Series of LAA tests were conducted to accelerate the ballast particle breakage and abrasion, in a sequence of 250 turns of the LAA test drum, after which the changes in gradation and morphological properties were quantified. The morphological properties were quantified using imaging techniques (Aggregate Image measurement system (AIMS)). At the end of the study, the overall results showed that ballast degradation has a strong correlation with the ballast particle's morphological properties. The relationships and the indices of morphological changes can be used for numerical modeling and simulations using discrete element method (DEM) to study the performance of ballast at different degradation levels.

Several tests are normally used to analyze the resistance of rocks and ores to breakage in the mining/aggregate industries. Some of these tests yield results that serve as basis for either simple mathematical expressions or comprehensive models, whereas others are essentially only used to classify a rock or ore in comparison with others. The present work demonstrates that the outcomes of three of these tests, namely the Bond crushability index, the JK Drop Weight Test and the Los Angeles abrasion test, can be predicted from simulations using the discrete element method with polyhedral particles with a particle replacement model. In addition to that, a sensitivity analysis of the predictions for the drop weight test results on the basis of selected simulation variables is analyzed, resulting in recommendation of optimal values. The work demonstrates the validity of the breakage model and its ability to describe outcomes of tests that are recognized to capture different aspects of the breakage response of brittle particulate materials.

Purpose. Wear and increased surface roughness are among the reasons for failure of posterior composite restorations. Considering the widespread use of bulk-fill composites in the posterior region, information about their wear resistance is imperative. The aim of this study was to compare the wear and surface roughness of four bulk-fill composite resins with a conventional composite. Methods. Thirty composite discs ( 4 mm × 10 mm ) were fabricated from EverX Posterior (GC), X-tra fil (Voco), Filtek Bulk-Fill Posterior (3M, USA), SonicFill 2 (Kerr), and Z250 (3M) composites. The baseline weight and surface roughness of specimens were measured. For the assessment of the attrition wear, the specimens were placed in a chewing simulator (Mechatronik). pH cycling was performed to erode the composite discs. They were then placed in a tooth brushing simulator machine (Dorsa) for abrasion wear. Finally, the weight and surface roughness of the specimens were measured. Data were compared using one-way ANOVA ( alpha ≤ 0.05 ). Results. One-way ANOVA showed that the mean weight changes were significant after attrition, abrasion, and erosion ( P = 0.019 ), but changes in surface roughness were not significant ( P ≥ 0.05 ). The results of Tukey’s test showed no significant difference between the bulk-fill composites and Z250 regarding weight loss ( P ≥ 0.05 ), but the weight loss of X-tra fil was significantly greater than that of EverX ( P = 0.007 ) and Filtek Bulk-Fill ( P = 0.005 ). Conclusions. Considering the limitations of this study, it appears that the wear and surface roughness of bulk-fill composites are within the acceptable range and are not different from those of a conventional composite.

In this paper, based on the thermosetting properties, bonding performance, high-temperature water damage resistance, and aging resistance properties of epoxy-emulsified asphalt, the best formulation of epoxy emulsified asphalt as a skid resistance fog sealing asphalt is studied. Through accelerated wheel wear and other tests, the effects of the ratio of the amount of skid resistance particles to the amount of epoxy emulsified asphalt, the total amount of skid resistance fog seal asphalt, and the construction process on the skid resistance durability of the skid resistance fog seal were studied. The results show that the epoxy emulsified asphalt formula code A80 (E2) (emulsified asphalt : water-based epoxy = 80 : 20) is the best formula; when the proportion of emery and epoxy emulsified asphalt is 1 : 1, the British Pendulum Number (BPN) reduction rate of the skid resistance fog seal-test piece worn 100,000 times was 27.4%. Compared with the same period, the reduction rate was reduced by 4.6% on average, with the smallest mass loss rate and the best skid resistance durability. When the total amount of skid resistance fog seal asphalt is 1.2 kg/m2, the BPN reduction rate of the skid resistance fog seal specimen worn 100,000 times was 27.4%, which is an average reduction of 5.8% over the same period, and the mass loss rate is the smallest, and the skid resistance durability optimal. When using the premixed process, the BPN of the specimen was reduced by 13.2% after abrasion of 100,000 times. Compared with the “one asphalt and one sand” and “double asphalt and one sand” molded specimens, the mass loss rate was reduced by 15.0%, 4eU&7.2%, showing the best skid resistance performance. The results can provide guidance for the design and construction of AC-13 and other pavement skid resistance fog seals.

The present study investigates the micromechanical properties of ceramic coated WC/Co tools and their influence on wear performance during dry Ti6Al4V turning. Physical and micromechanical characterization have been performed for the evaluation of the PVD coating properties. Higher hardness, elastic modulus, and adhesion strength have been obtained for dual-layer (AlTiN/AlCrN) coated tool than monolayer AlTiN and AlCrN coated tools. Micromechanical properties influence the wear mechanisms in thermally activated and abrasion dominant crater zones. Dual-layer coated tools reduced the flank wear at the corner radius and crater wear by 35–50% and 40%, respectively. Dynamic wear and abrasion-dissolution wear mechanisms have been explored over the tool rake face. Dual-layer coatings have improved wear performance by diminishing delamination, micro-fracturing of WC grains, binder dissolution and fractured interface boundaries.

The uniformity of rice milling is of vital significance in the rice processing industry. Unfortunately, the reasons for non-uniform milling of grains in friction rice mills still remain poorly understood. In this paper, the motion of rice in the mill is numerically simulated based on the discrete element method. The removal mechanism for the bran layer in the friction mill is discussed and verified by experiment. A method of quantifying milling uniformity was introduced. The results showed that for successful milling, the intact bran layer must experience abrasion caused by sieve-rice contact then be completely removed by rice–rice friction. Non-uniform milling occurs due to the existence of “milling blind zones”, where the bran layer cannot be removed. Milling uniformity is closely related to the ability of rice to move from blind zones to the outer ring of the mill. The use of alternating rate to quantify this ability is proposed. The higher alternating rate the better milling uniformity. Alternation rate is affected by the tumbling movement of rice in the milling cavity. The research helps clarify the milling process of rice and provides guidance for the design of rice friction mills.

Al matrix composites reinforced with ceramic particles show excellent wear resistance and have great potential to replace convectional materials in many fields. In this paper, a high proportion (∼ 60%) of large ZrO2 particles reinforced Al matrix composites were manufactured by a high pressure infiltration method. The tribological behavior of the Al/ZrO2 composite and non-reinforced Al were investigated and compared using a GCr15 ball-on-disc apparatus under dry sliding wear condition. The microstructure, elements distribution and wear track morphology were analyzed to understand their tribological behavior and wear mechanisms. The wear rate of Al is 2.0 × 10−3 mm3 N−1 m−1, while the wear rate of Al/ZrO2 composite is only 0.15 × 10−3 mm3 N−1 m−1. The experimental results showed that Al is a combined wear mechanism of adhesive wear and abrasive wear. It also proved that the high proportion of large ceramic particle reinforced composite is stable under low load wear condition. The ceramic particles were firmly embedded in the Al matrix, and no ejection or removal of the particles was observed. The results showed that the wear mechanism of this composite is mainly three body abrasion in the stable wear stage.

The quantitative assessment of profile damage of square (SQ) and threaded with three intermittent flat faces (TIF) tool pin was appraised and presented for both uncoated and AlTiN coated tools during friction stir passes on AA6061-T6 plates successively after different travel lengths. Significantly lower profile damage with small amount of profile twisting was noted for TIF tool pin as compared to the SQ tool pin owing to lower force and torque, as predicted by finite element (FE) results. For AlTiN coated tools, the pin profile damage reduced significantly due to high wear resistance, hardness and good adhesion of coating with the tool substrate. Significantly lower temperature rise was noted in the AlTiN coated tool compared to the uncoated tool. A mathematical approach to predict the heat generation was presented and predicted temperatures were found in good agreement with FE results. Plastic deformation of sharp corners, adhesion and abrasion wear of flat faces, and initiation of crack near tool pin-shoulder interface was noted in uncoated tools however, they got reduced in the AlTiN coated tool. The delamination of coating near the tool pin edge, flat surfaces and near the tool pin-shoulder interface was noted due to dislodging of adhered work material. Fairly uniform tensile strength and flexural load were obtained after different weld lengths for AA6061-T6 FSW joints prepared with the AlTiN coated TIF tool pin.

In this research, Y2O3 nano particles were dispersed into Aluminum A356 via ultrasonic assisted stir casting route. Microstructural analysis confirmed that ultrasonic aided synthesis significantly helped in homogenous dispersion of particles; excellent bonding between matrix and reinforcement and at the same time significantly refined the dendritic microstructure. Addition of nano Y2O3 particles and ultrasonic treatment had a tremendous impact on the hardness of developed composites. Sliding wear characteristics of the developed composites were investigated under varying sliding speeds and loads. Wear test results confirmed that addition of nano Y2O3 particles comprehensively decreased the A356 alloy wear rate, and SEM analysis of the worn out samples revealed delamination, oxidation and abrasion, plastic deformation wear to be the predominant wear mechanisms.

Low Infrared emissivity coating (LIREC) is prone to generating some problems such as bulges, degumming, and abrasion. In order to study whether the performance of LIREC under different damages can meet the work needs, it is essential to timely measure and evaluate the performance state of LIREC in the application process. The existing methods for measuring the damage of LIREC have some disadvantages such as expensive equipment, complex operation, and inaccurate measurement results. In this paper, a measurement method of LIREC damage capability based on thermal imager is proposed. The radiation temperature is measured by thermal imager, the real temperature and ambient temperature of coating surface are measured by thermocouple, and the emittance of coating surface is calculated. Non-contact and continuous large-area emissivity measurements are carried out on the damaged parts of the coating and verified by experiments. The measurement results show that the different damage types and damage degrees directly affect the measurement results of LIREC. Wear damage increases the emissivity of the coating while debonding damage basically does not change the coating emissivity. Shedding damage of small diameter forms voids, which causes the increase of the damage parts of emittance. In addition, bulge damage impedes temperature transfer and reduces emissivity. This method can timely and accurately measure and evaluate the performance state of LIREC and can provide a new idea for the accurate measurement of damage emissivity of LIREC.

The influence of severe plastic deformation induced by ultrasonic shot peening (USP) on evolution of microstructure and the resulting properties of 316 austenitic stainless steel is evaluated. Microstructural characterization was carried out by using optical, scanning, and transmission electron microscopies in addition to electron backscattered diffraction, x-ray diffraction and x-ray photoelectron spectroscopy. Mechanical properties were evaluated using hardness and sliding wear tests. USP resulted in high dislocation density and refined microstructure that led to significant increase in hardness. Although no strain induced martensite formed after USP at room temperature, USP carried at cryogenic temperatures led to martensite formation indicating the importance of temperature in USP on strain induced martensite development. Contrary to this, sliding wear at room temperature led to martensite development suggesting dominant role of deformation mode on martensite development during sliding wear. Sliding wear mechanism involved abrasion of steel accompanied by plastic deformation. Localized corrosion resistance improved due to nanostructured surface produced after USP enhancing the diffusional transport of chromium to surface. XPS analysis revealed higher Cr: Fe ratio in the oxide film after USP. Simultaneous enhancement of wear and corrosion resistance of stainless steels by the application of USP is discussed.

Inconel 718 is widely used in many applications specifically in the aerospace and nuclear industry due to its superior properties in strength, hot hardness, and thermal and corrosion resistance. However, it is classified as difficult-to-cut material due to its extreme hardness that led to high cutting forces and temperature which further worsened by its strain hardening effect. Thus, it is crucial to analyze the different types of wear mechanisms and failure modes, to analyze causes, and also to understand how cutting parameters affect the wear mechanisms and failure modes. The study is conducted with PVD TiAlN-NbN coated inserts with varying cutting speeds (40, 60, and 80 m/min) and varying feed/tooth (0.7, 0.1, and 0.13 mm/tooth) under the wet condition of face milling. The flank wear progression and length of cut were measured and recorded to study the tool life against length of cut. The tool wear and failure modes of inserts were observed under the optical microscope and SEM/EDX. Results showed that cutting speed has a major effect on the tool failure as compared to feed/tooth. At low speed, the dominant tool failures were macro-chipping due to the severe BUE (built-up edge)/BUL (built-up layers) formation. At higher speeds, the dominant tool failures were flaking and notching which led to the sudden tool breakage. At low feed/tooth, the dominant failures were flaking and macro-chipping, but notching and tool breakage became dominant at higher feed/tooth. Moreover, it is found that the main wear mechanisms which contributed to the tool failures were adhesion, abrasion, thermal and mechanical cracks, diffusion and oxidation wear.

In the present study, we demonstrated a novel process of in-situ fabrication of graphene sheets by adopting the chemical vapor deposition (CVD) method. Fabricating such a layer of vertical graphene sheets (VGs) on the surface of microcrystalline diamond (MCD) films could decrease the stable coefficient of friction (COF) by 20–30%. Besides, such lubricity showed excellent load capacity and durability. With normal loads ranging from 3 N to 9 N (Hertz contact pressure of 2.1–3.1 GPa), the MCD-VGs films exhibited COFs stabilized at 0.105 and wear rates less than 5 × 10−6 mm3 N−1 m−1. Additionally, the produced VGs displayed an excellent service lifetime with 72,000 sliding cycles. During the friction tests, an equilibrium graphene self-mated contact formed on the sliding interface as graphene fragments adhered onto the counterpart ball and resulted in the reduction of friction and low wear rates. Additionally, the mixtures of Si3N4/SiO2 particles and graphene sheets residual within the wear tracks would promote the transformation of the sliding regime to three-body abrasion, beneficial for friction reduction. The findings presented in this study provide a novel and effective approach to enhance the lubricity of any engineering diamond surface.

TiN/Ni alloying of 38CrMoAl steel surface was carried out by continuous scanning electron beam. The effect of electron beam process parameters on the surface microstructures and mechanical properties of 38CrMoAl steel was studied. The results shows that the sample surface was divided into three regions: alloying layer, heat affected zone and substrate. Alloying layer made up with equiaxed crystals and short columnar crystals, microstructure of the heat affected zone was acicular and lath martensite, microstructure of substrate was tempered sorbate. The microhardness of the sample section first increased and then decreased, at a depth of 400 μm, the microhardness reached a maximum of 817.9 HV. When the beam current reached 12 mA and the moving speed reached 5.5 mm/s, the surface microhardness of the sample reached the highest 1209HV and the abrasion loss reached the lowest 4.6 mg.

Disc cutter wear is a crucial problem that influences the working efficiency and security of hard rock tunnel-boring machines (TBMs). When tunneling and rock breaking with TBM, the cutters at the forefront of the cutter head directly contact the tunnel face, where wear is serious due to a harsh working environment. In this study, the Cerchar abrasivity index (CAI) of various rock samples was obtained by using the ATA-IGG I rock abrasion servo system. Additionally, a series of small-size cutter wear experiments were carried out on an SP3-I composite abrasion test platform, and the fitting relationship between cutter wear and rock abrasion value was obtained. A cutter wear prediction method was established by measuring the cutter wear and rock CAI of the project built section and the rock CAI of the project unbuilt section. Based on the experimental results, the effects of different tunneling parameters (penetration speed, rolling speed) and tip width on cutter wear were analyzed. In the study of cutter wear, attention should be paid to the influence of load, vibration and temperature on the cutter wear removal mechanism. It is suggested that wide-tip and narrow-tip cutters should be arranged alternately on a TBM cutter head to give full play to the lateral rock crack ability developed by the wide-tip cutter and the radial rock crack ability developed by the narrow-tip cutter, so as to reduce wear on the cutter and improve the efficiency of TBM rock breaking. The results of this research provide a reference for optimization design and performance selection of a TBM cutter ring and cutter head.

In this research, the TiC-Ni35A composite coating was fabricated on the AISI 1045 steel substrate by laser cladding process. The cross-sectional morphology, microstructure, micro-hardness, and wear resistance of coatings obtained under different laser energy densities (E) and TiC powder ratios (PR) were analyzed. According to the results, all the coating had a reliable metallurgical bonding with the AISI 1045 steel substrate. The X-ray diffraction (XRD) analysis revealed that the coating phases were Ni and TiC. The average microhardness of the Ni35A-80wt.% TiC coating reached up to 75.12 HRC. The minimum coefficient of friction of the composite coating was only about 30% of the AISI 1045 substrate. The wear form was mainly adhesive wear when altering the TiC powder ratios, while the wear form also contained abrasion wear under different energy densities. The ability of decomposition and re-nucleation of TiC was significantly improved with the increase of laser energy densities and the decrease of TiC powder ratios. The micro-hardness, wear resistance, and coefficient of friction of the composite coating were improved because of the TiC strengthening phase particles. Compared with the AISI 1045 steel substrate, the micro-hardness and wear resistance of the composite coating was increased by 5.29 times and 6.26 times, respectively.

Steel slag aggregates with three surface texture levels were produced by utilising Los Angeles abrasion machine so as to evaluate the influence of aggregate surface texture on porous asphalt mixtures (PAM) . A series of laboratory measurements were conducted to determine PAM’s properties. Discrete element method (DEM) simulations were applied to obtain four packing parameters of porosity, coordination number, proportion of effective particles, and average contact force to assess the packing structure of corresponding PAM designs. The results indicated that aggregate surface texture significantly affects the mechanical properties of PAM, in which doubling the roughness of aggregate surface increases Marshall stability by around 16% and decreases permanent strain by about 40%. Rougher surface mitigates slippage between aggregates particles, thereby creating a more stable aggregate packing in PAM.

The shear behavior and drainage characteristics of coal-fouled ballast when treated with elastomeric polyurethane are assessed by means of large-scale direct shear and permeability tests. The results from direct shear tests confirmed that the shear strength of both stabilized and unstabilized coal-fouled ballast was highly influenced by the extent of fouling (VCI: void contamination index). The performance index (PI) of elastomer-stabilized coal-fouled ballast (ESFB), determined as the fraction of shear strength of fouled ballast to the shear strength of fresh and unstabilized ballast, lies in the range of 1.23 to 0.84. Moreover, the performance of ESFB having VCI ≥30% was found to be either similar to or poorer than that of clean ballast without any treatment, thus indicating that the elastomer treatment may be provided only to ballast with VCI ≤30%. The results from constant head permeability tests indicate that the hydraulic conductivity of ballast ( k) is highly influenced by the presence of fouling materials but is only slightly reduced as a result of the elastomer stabilization. The k of ballast decreased from 43 to 0.18 mm/s as the VCI increased from 0 to 75%. For VCI ≥ 45% the k of ballast was found to be lower than that recommended for sub-ballast. On the other hand, the k of ballast reduced slightly from 43 to 37 mm/s because of the elastomer stabilization. Furthermore, an empirical relationship is established between k and e to determine the k of both stabilized and unstabilized fouled ballast.

The dry sliding wear behavior of A7075 based composites strengthened with particulates of ZrB2 was examined using the pin-on-disc device. The composites were synthesized by reinforcing different weight % (5, 10, and 15) of the ZrB2 using a stir casting technique followed by hot extrusion. The dry sliding wear resistance is optimized under varying conditions of sliding velocity, sliding time, and load. The sample's worn-out surfaces were examined using scanning electron micrographs to obtain the composites' wear mechanism. Delamination, abrasion adhesive modes of deformation were observed. The wear parameters were optimized with Grey relational analysis (G.R.A.) and ANOVA techniques and obtained the optimal combination of input parameters.

Nickel based super alloys are considered as difficult to machine materials. These days, the sustainable cooling system are applied at the cutting zone for enhancing the machining performance of nickel based super alloys. Therefore, the present work focusses on the machining aspects of Nimonic 80A under different cooling conditions. Moreover, the turning experiments were performed under dry, minimum quantity lubrication (MQL different positions) and nano-MQL (different positions) conditions and the influence of nozzle position during MQL and nano-MQL were investigated. The tool wear, surface roughness, mechanism promoting tool wear, power consumption and chips morphology were investigated under these subjected conditions. The outcomes of this study state that the position of MQL nozzles plays an important role to improve the machining performance of Nimonic-80 alloy. The total tool wear is approximately 60% better for nano-MQL (mixed direction) than dry conditions. The results also stated that abrasion and adhesion are prompting tool wear mechanisms observed under dry conditions.

In the present work, the microstructure, hardness, and wear behavior of the Ti–6Al–4V alloy was studied under different heat treatment conditions. For this purpose, four samples were annealed at temperatures from 800 to 1050°C for 1 h and then quenched in water and air. One of the samples was aged at 550°C for 4 hours. Microstructural investigations by optical microscopy and scanning electron microscopy demonstrated that the solution annealing at 800°C leads to a limited precipitation growth without changing microstructure and increasing hardness. By increasing the solution annealing temperature and consequently quenching in water, higher hardness was obtained along with the formation of α and α' martensite. The solution annealing at 1050°C caused the formation of the martensite phase which would be transformed to disorder the β phase; due to this phase transformation, hardness increased up to 47% compared to the hardness of the controlled sample (as receive). The n all of the samples, with or without heat treatment, the oxidative abrasion mechanism was observed along with signs of shear wear. In all of the samples, with or without heat treatment, the oxidation abrasive wear mechanism was observed along with signs of lamination wear.

To improve the dry friction behavior of traditional hard coatings, MoS2/PTFE lubricating coatings were prepared on the PVD TiN-coated cemented carbide using spray method. The influences of MoS2/PTFE lubricating coatings on the primary characteristics of TiN coatings were investigated. Reciprocating sliding tests were carried out with the TiN–MoS2/PTFE coated specimen (T-M-P) under dry sliding conditions, and the tribological behaviors were compared to those of the TiN-coated one (T-N). The test results indicated that the adhesion force of coatings with substrate for T-M-P specimen increased, the surface micro-hardness, roughness and friction coefficient significantly decreased. Meanwhile, the surface adhesions and abrasion grooves of T-M-P specimen were reduced, and the main wear forms of T-M-P were abrasion wear and coating delamination. The MoS2/PTFE lubricating coatings can be considered effective to improve the friction properties of traditional hard coatings.

The present investigation deals with development of AA2219 composites with different weight fractions of Cerium oxide (CeO2) reinforcement and characterizing the microstructure and mechanical properties thereof. XRD and SEM micrograph confirm the presence of CeO2 particles and Al2Cu precipitate. The grain size of 0, 0.5, 1.0, 1.5 and 2 wt% CeO2 composites are 483, 453, 411, 362 and 328 μm, respectively. Addition of CeO2 significantly reduces the dendritic morphology and refines the α-Al grain structure. 2 wt% CeO2 addition has yielded the maximum hardness of 124 HV and yield strength of 87 MPa in all the composites developed. Additionally, the developed composites were evaluated by examining the wear characteristics with the co-efficient of friction (COF) and the specific wear rate. In this study, Taguchi's L25 orthogonal array was used to optimize the parameters like reinforcement fraction, load and sliding distance. Signal-to-noise ratio (S/N ratio) and analysis of variance (ANOVA) are used to obtain the parameters highly influencing the wear behaviour. Adhesive wear is exhibited by ploughing at lower loads and delamination is observed with increasing load. Deep shallow ploughs with embarked abrasion are observed at higher loads.

In metal machining, a large amount of heat is generated which significantly affects the machining performance, and therefore, a suitable cooling/lubricating strategy is required to control this heat. The consumption of applied coolant is a hazard for biological and ecological concerns. However, this work implemented three distinct cutting environments (dry, MQL (minimum quantity lubrication) and SIC (spray impingement cooling)) to study the tool wear, surface roughness, surface topology, cutting temperature and chip morphology in turning of Ti-6Al-4V ELI alloy. SIC is one of the new cooling strategies in which atomized water spray impinges into the cutting region with the help of compressed air. Ti-6Al-4V ELI alloy machining is difficult due to its poor thermal conductivity, highly reactive at elevated temperature, etc. Considering the machinability results, MQL exhibited the lower flank wear and surface roughness over dry and SIC cutting conditions, while very low temperatures were obtained under SIC compared to dry and MQL cooling conditions. Abrasion, notch wear, adhesion and diffusion mechanisms are the primary mode of wear identified. The tool life under dry, MQL and SIC cooling conditions is estimated as 540 seconds, 1500 seconds and 995 seconds, respectively; however, MQL cooling-assisted turning exhibited 177.77% larger tool life relative to dry cutting and 50.75% longer tool life compared to SIC turning; thus, MQL optimal condition (ap = 0.2 mm, f = 0.12 mm/rev, v = 79 m/min) is recommended to utilize for turning of Ti-6Al-4V ELI alloy for industrial applications.

In the present study, the influences of different SiC addition, MWCNTs and various SiC particle sizes on the structural, mechanical and tribological properties of ZC71 alloys were studied. The results revealed that the proper amount/size of SiC particles with the addition of MWCNTs had a considerable effect on the microstructural alteration, and mechanical and tribological properties of the ZC71 alloy. The Vickers hardness values of the ZC71 alloy improved with the addition of MWCNT and SiC. The UTS (216 MPa) and El.% (6.95 %) were achieved in the ZC71-5%SiC(15µm)-0.5%MWCNT. The cast ZC71 alloy showed brittle fracture with some quasi-cleavage characterizations. However, by adding 5% SiC(15 µm) and 0.5% MWCNT, the fracture mode changed to ductile fracture. The wear results showed that the ZC71-5%SiC-0.5%MWCNT hybrid composite had the highest wear resistance with the lowest friction coefficient and wear rate. Examination on the worn surface of the ZC71-5%SiC-0.5%MWCNT hybrid composite showed mild abrasion as the governing wear mechanism.%2

Shoreline dynamics naturally occur in coastal areas, and over time, are also influenced by anthropogenic processes taking place both on-site and upstream. Bordering the Indian Ocean, the coastal area of Bantul Regency in the Special Region of Yogyakarta is faced with typical strong and high waves that induce changes in its shoreline dynamics and activities. Consequently, tourism, a leading economic sector in the area, often needs to adjust to such changes. Here, shorelines were extracted from the spatial data of time-series Sentinel 2A imagery (2015, 2016, 2017, 2018, 2019, and 2020) using water index transformation, MNDWI, while the land cover changes were analyzed using the Decision Tree classification. Based on the results, accretion appeared most significant from 2016 to 2017, creating an additional 22.32 ha. In contrast, shoreline change from 2019 until 2020 indicated the most severe abrasion that led to a loss of 34.89 ha. The highest rate of landward shoreline change was 41.58 m/year.

As is well known, titanium alloy precipitates when subjected to aging treatment, which poses great influence on its mechanical properties. Thus, solution and solution-aging treatments were conducted in this work, and the wear performance was investigated under different normal loads. The results showed that acicular α′ martensite in the original selective laser melted Ti–6Al–4V was decomposed into α + β phases after the solution treatment, and then Ti3Al nanoparticles clusters were further formed in the α-matrix after the solution-aging treatment. The coefficient of friction decreased straightly as the normal load was increased from 20 to 100 N, and the wear mechanisms were characterized by abrasion, adhesive and oxidative wears. The wear rate of solution and solution-aging treated samples increased significantly comparing to the as-built counterpart, but the increment of the solution-aging treated sample was smaller than that of the solution-only treated sample, because of the Ti3Al precipitation in the solution-aging treated sample. These particles provided ball-like effect, reduced material losses and stabilized the wear process. All these factors contributed to the improvement in wear properties of the parts made by selective laser melting.

The process of lubricant penetration into frictional interfaces has not been fully established, hence compromising their tribological performance. In this study, the penetration characteristics of deionized water (DI water) containing an electroosmotic suppressant (cetyltrimethylammonium bromide (CTAB)) and an electroosmotic promoter (sodium lauriminodipropionate (SLI)), were investigated using steel-on-steel friction pairs. The results indicated that the lubricant with electroosmotic promoter reduced the coefficient of friction and wear scar diameter, whereas that with an electroosmotic suppressant exhibited an opposite behavior compared with DI water. The addition of SLI promoted the penetration of the DI water solution, thus resulting in the formation of a thick lubricating film of iron oxide at the sliding surface. This effectively reduced the abrasion damage, leading to a lower coefficient of friction and wear loss.

Understanding the wear of mineral fillers is crucial for controlling industrial processes, and in the present work, we examine the wear resistance and nanomechanical properties of bare calcite and stearic acid-modified calcite surfaces under dry and humid conditions at the nanoscale. Measurements under different loads allow us to probe the situation in the absence and presence of abrasive wear. The sliding motion is in general characterized by irregular stick-slip events that at higher loads lead to abrasion of the brittle calcite surface. Bare calcite is hydrophilic, and under humid conditions, a thin water layer is present on the surface. This water layer does not affect the friction force. However, it slightly decreases the wear depth and strongly influences the distribution of wear particles. In contrast, stearic acid-modified surfaces are hydrophobic. Nevertheless, humidity affects the wear characteristics by decreasing the binding strength of stearic acid at higher humidity. A complete monolayer coverage of calcite by stearic acid results in a significant reduction in wear but only a moderate reduction in friction forces at low humidity and no reduction at 75% relative humidity (RH). Thus, our data suggest that the wear reduction does not result from a lowering of the friction force but rather from an increased ductility of the surface region as offered by the stearic acid layer. An incomplete monolayer of stearic acid on the calcite surface provides no reduction in wear regardless of the RH investigated. Clearly, the wear properties of modified calcite surfaces depend crucially on the packing density of the surface modifier and also on the air humidity.

The aggregates consist approximately 85% of the total volume in asphalts pavements, and their properties influence directly their behavior. Therefore, it is essential to pre-study aggregates before using them in asphalt pavements. This paper evaluates the geological-geotechnical properties of high-grade metamorphic felsic rock, for use in asphaltic paving, and their issues of adhesiveness to the asphalt binder. The aggregates studied here come from Iterere Quarry, located in Campos dos Goytacazes, a northern region of Rio de Janeiro state. The quarry provided for the study aggregates in granulometry grit 0, 1, and stone powder. The geological study showed that the aggregate is a quartz-feldspathic rock, with felsic composition, framed in the granulite metamorphic facies. The aggregates show open graduation, and the maximum aggregate size is 19.1 mm. The real coarse aggregate density is 2.72 g/cm3 and the fine aggregate is 2.65 g / cm3, moreover, the water absorption was 1%. The mechanical resistance determined in tests was 30% abrasion Los Angeles and 12.7% loss of chock in Treton. The interaction of the aggregate with the asphalt binder from the adhesion test was unsatisfactory. It can be seen that the low percentage of asphaltene in the asphalt binder had a negative influence on aggregate adhesiveness.

This paper focused on ice processing and snow melting on urban pavement during the winter time in South China under the emergent situation. A kind of electrothermal cushion with carbon fiber was developed to improve resistance to skidding of pavement in winter and help melt ices and snows on the surface of pavement to ensure driving safety. This special cushion is composed of multilayer materials and structures. Laboratory tests for the cushion were conducted to analyze its electrothermal performance, heating uniformity, effect of ice melting, skidding resistance and frictions. At the same time, the durability of the ice melting cushion was evaluated. The results indicate that the developed anti-skidding electrothermal ice melting cushion with carbon fiber is stable in heating ability, high in heating speed, and the surface and bottom temperature of the ice melting mat during operation is not more than 30 ℃ without burning pavements and wheel tires, and the melting rate can reach 78.7% for one hour. The cushion can achieve excellent skid resistance and interlayer friction performance. The cushion can completely meet the requirements such as repeated rolling compaction under vehicle load, abrasion, bursting, etc., and have good durability. Therefore, the cushion is recommended to directly be placed on the pavement surface without interrupting traffics to improve the anti-skidding performance and short-term ice and snow melting in winter. The cushion has lower heating and deicing cost and has a better deicing effect and better economic benefits. Moreover, the cushion only needs to be used in winter, which extends its service life and can be reused without adverse impact on road performance.

The use of solid particles as a heat transfer medium is being explored for concentrated solar power plants (CSP) to increase their efficiency by achieving operating temperature >700 °C. During operation, these hot particles are expected to move along the various components within the collector system, resulting in material degradation from a combination of high-temperature oxidation and erosion. In the present study, the performance of candidate materials was evaluated through a series of abrasion erosion experiments at room temperature as well as at 800 °C. Wear in metallic and refractory type materials was investigated using CarboBead® HSP 40/70 particles inside a resistance heated kiln. Cross-sectional scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) analysis on the specimens tested at 800 °C determined that the specific wear rate in Inconel 740H and stainless steel 316 metallic specimens was influenced by the thermally grown oxide morphology. High chromium Inconel 740H specimens exhibited greater resistance to wear with a steady state specific wear rate of 1.92E-4 mm3N-1m−1 compared to 5.7E-3 mm3N-1m−1 for Stainless Steel 316.

• Crust strength and stiffness reduce by expanding sandblasting duration.• The overlap between the PDFs of the unit impact energy and strength increases over time.• Determining the overlap changes provides a framework for predicting crust durability.

Objective: Aluminium and its alloys components are used in aero and space industries where in many cases trioboloading prevails. In space application, in addition to triboloading, the components should also perform in the absence of atmosphere. In the present investigation, attempted has been made to simulate the field conditions in the laboratory by sliding Al6061 alloy pin of different diameters in a vacuum at different temperatures using a vertically configured pin-on-disc test rig. Method: The pin diameters were 2, 4, and 6mm and the testing temperatures were 373, 473, and 573K. The normal contact pressure was 0.625MPa and the sliding speed was 0.5ms-1 and both were constant throughout the experiment. The coefficient of friction was monitored using a PC and the worn pin surface was studied in scanning-electronmicroscope. Findings: The result showed that the coefficient of friction at sliding temperatures 373 and 473K was found to be dependent on apparent contact area i.e., pin diameters 2, 4, and 6mm. The coefficient of friction was found to be 3.27 and 2.69 for pin diameter 2mm at temperature 373 and 473K whereas the coefficient of friction was of the range 1.36 to 0.33 for the pin of diameter 4 and 6mm. The scanning-electron-microscopic study revealed uniform plastic deformation for pin diameter of 2mm and non-uniform plastic deformation accompanied with abrasion extrusion phenomenon for the pin of diameters 4 and 6mm. The coefficient of friction at sliding temperature 573K was found to be insensitive to the apparent contact area. The coefficient of friction was in the range of 1.24 to 2.30. The SEM study revealed a large scale of non-uniform plastic deformation accompanied by abrasion, tearing of ridges, extrusion of both ridges, and entrapped wear debris. Novelty: It is a generic study for understanding the response of aluminium for tribo loading which. Keywords: Pin on Disc (POD); Scanning Electron Microscope (SEM); High Temperature; Vacuum; Coefficient of Friction; Al6061 Aluminium Alloy 1

The estimation of soil abrasivity and cutting tool wear during soft ground tunneling is complicated and arduous work due to the lack of a generally accepted testing system. To date, geotechnical baseline reports (GBRs) and geotechnical data reports (GDRs) still cannot provide reliable soil abrasion indices for tool life prediction. This is considered a deficiency in the geotechnical investigation of shield-driven tunnel projects. In this study, the Multifunctional Shield Test System (MSTS) developed by the Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province at Wuhan University is presented. The MSTS was motivated by the need for a test platform with the ability to simulate undisturbed soil conditions and actual tool working environments to explore the mechanism of cutting tool wear, bentonite slurry penetration, and filter cake formation in various geomaterials with grain sizes including clay, silt, sand, and gravel (

In this study, AA7075 aluminum matrix composites reinforced with the combination of SiC, Al2O3, and B4C particles were fabricated by the liquid metal infiltration method. The effects of the relative ratio of B4C and Al2O3 particles on the microstructural, wear, and corrosion features of the composite samples were analyzed using XRD, light metal microscopy, SEM, EDS, Brinell hardness, ball-on-disc type tribometer, and potentiodynamic polarization devices. It was determined that infiltration occurred more successfully, and homogenously distributed particles with reduced porosity were obtained as the amount of Al2O3 increased. Worn surface studies revealed that the specimens were predominantly worn by abrasion and adhesion. The increase in B4C/Al2O3 ratio caused a decrease in the hardness and wear strength, whereas it increased the corrosion resistance.

Aim: To evaluate the effect of hydro abrasion versus the conventional drill method of cavity preparation on the clinical performance of composite restoration over one year follow up period. Materials and methods: Twenty patients with occlusal carious lesions were selected and examined with DIAGNO cam and ICDAS visual criteria to select teeth having ICDAS Code 3 or 4. Forty lesions were randomly divided into two groups (n=20) according to the method of caries removal. Cavities were prepared by the conventional drill method in group I and by hydro-abrasion in group II. Cavities of both groups were restored by self-etch adhesive (Adper Easy Bond) and nano- filled composite (Filtek Z350XT). All restorations were evaluated after 24 hours, after 9 and 12 months according to (USPHS) criteria for retention, marginal adaptation, postoperative sensitivity, marginal discoloration, and secondary caries. Results: Mild, moderate - severe and very severe pain was recorded in group I While in group II, only mild pain was recorded in (40%) of cases. The st. analysis of the collected data related to the tested USPHS criteria revealed 100% Alpha scoring regarding retention, marginal adaptation and secondary caries in both groups throughout the study period. The gap width measured under SEM was found increased sig. by time in both groups. Marginal discoloration was observed in the two groups after nine and 12 months. Post-operative hypersensitivity was found only in group I in 100% of cases at the base line and was disappeared during the next follow up period.

Objectives The aim of this laboratory study was to evaluate the wear resistance of crowns made from current computer-aided design and computer-aided manufacture (CAD/CAM) materials. In addition, the abrasion of the steatite antagonist against these materials was compared. Methods Identically shaped crowns of lithium disilicate, zirconia-reinforced lithium disilicate and a polymer-infiltrated ceramic network (PICN) were fabricated with an occlusal thickness of 1.5 mm and a lateral wall thickness of 1.2 mm (n = 8). The crowns were cemented with a dual-polymerizing luting resin on composite resin dies. Using spherical steatite antagonists, all specimens were loaded with 49 N for 1,200,000 cycles in a mastication simulator with additional thermocycling. After 120,000, 240,000, 480,000, 960,000, and 1,200,000 cycles, precision impressions were made and investigated with a laser scanning microscope. The vertical and volume substance loss was measured. Additionally, the substance loss of the antagonists was evaluated after 1,200,000 loading cycles. Results No significant difference (p > 0.05) was found in the median volume loss of the test materials after 1,200,000 cycles (lithium disilicate: 0.405 mm3, PICN: 0.362 mm3, zirconia-reinforced lithium disilicate: 0.340 mm3). The vertical substance loss of PICN (157 μm) was significantly lower (p ≤ 0.05) than that of lithium disilicate (201 μm) and zirconia reinforced lithium disilicate (191 μm). However, the substance loss of steatite against zirconia-reinforced lithium disilicate (0.191 mm3) was significantly lower (p ≤ 0.05) than against lithium disilicate (0.296 mm3) and PICN (0.531 mm3). Significance All three CAD/CAM materials showed wear resistance that seems appropriate for clinical application. Also, the abrasion of the antagonist looks promising.

This study aimed to evaluate the use of different pressure of air particle abrasion (APA) on four different types of monolithic zirconia and its effect on their shear bond strength. Methodology: The study was divided into 4 groups according to the type of monolithic zirconia used: opaque, high translucency, ultra-high translucency and supra-high translucency. Each group was subdivided into two groups according to the amount of APA application used (2 or 4 bars). For the treatment of the zirconia specimens, zirconia MDP containing primer was applied on the cemented surface. Composite resin cubes were fabricated and cemented over zirconia cubes under 5kg for 6 minutes.Shear bond strength test was carried out on an Instron machine at a speed of 0.5mm/min, with the load measured in Newtons and the SBS determined as follows: Load (N)/area = SBS. Effect of APA application were examined using scanning electron microscopy to determine surface roughness on different tested zirconia groups. The data was statistically analized. Results: The one way ANOVA test revealed statistical differences between the APA pressure groups (P

Piston skirts undergo important wear and abrasion due to poor tribological properties. A surface coating system with appropriate friction and hardness properties is proposed in this work to enhance the base material durability of iron alloy pistons. Aluminum-Silicon (Al-Si) thin film was deposited using vacuum evaporation process from 85 at.% Al and 15 at.% Si powders. The W-Ti-N thin film was deposited on the top of the Al-Si thin film using a PVD sputtering process from a W-Ti (70 at.% W and 30 at.% Ti) target onto a stainless steel substrate. The microstructural, mechanical and tribological properties of the multilayer were studied for potential applications on piston skirts manufactured from iron alloys. W-Ti-N/Al-Si multilayer shows a dense microstructure morphology with W2N (200) is the main phase present. Hardness measurements indicate that Al-Si thin film reached a value of 8.8 ± 0.37 GPa, while that of W-Ti-N/Al-Si multilayer reaches values as high as 17.2 ± 0.25 GPa. Tribological tests conducted on the multilayer system revealed interesting results, namely the very low values of the friction coefficient reaching μ ≈ 0.084±0.018 and that of the wear rate showing a value of k

The rolling indentation abrasion test (RIAT) is a recently developed method for measuring rock abrasivity. In this study, RIAT tests were performed on 17 plutonic rock samples and the weight lost by the mini-disc cutter (mg) after testing (RIATa), the mean value of 10 evenly distributed measurements of the cutter penetration depth into the rock in 1/100 mm (RIATi), abrasion-penetration rate (APR), and penetration-time rate (PTR) values were determined for the samples. The Cerchar abrasivity index (CAI), LCPC abrasivity index (LAC), and equivalent quartz content (EQC%) values were determined for the samples. The relationship of APR and PTR to CAI, LAC, and EQC% was investigated using regression analysis, and the Fisher test and empirical equations between APR-EQC%, PTR-EQC%, APR-PTR, PTR-CAI, APR-LAC, and PTR-LAC are proposed. The proposed equations were validated on three control samples and were found to be valid for plutonic rock. The RIAT test was used at different rotations speeds to determine their effect on the samples, and an optimal rotation speed has been proposed for each sample using the APR parameter. Comparison of the current results and those of previous research on sandstone showed that the trends of PTR-EQC%, APR-PTR, and PTR-CAI were similar. An experimental relationship has been proposed for these types of rock for APR-EQC%. For hard and highly abrasive samples, the trends for PTR-EQC%, APR-PTR, and PTR-CAI were similar for plutonic rock and sandstone, but for medium-to-high abrasivity samples, the penetration rate of plutonic rock was less than for sandstone in terms of abrasivity.

Cutter wear is an important factor affecting the efficiency of tunnel boring machines (TBMs). In this paper, using a case study from the tunnel project of the XEVIII section of the second phase of the northern Xinjiang water supply project, cutter wear under conditions of high-strength (average strength 120 MPa) surrounding rock is studied. The results show that the cumulative wear of the center cutters and the front cutters increases exponentially with an increase of installation radius, and the cumulative wear of the edge cutters is affected by the installation angle, which increases at first and then decreases with an increase of the installation radius. The single cutter wear of the edge cutters is the largest, of the front cutters is the second largest, and of the center cutters is the smallest. With an increase of surrounding rock strength, the wear of the center cutters and front cutters increases exponentially, and the wear of the edge cutters increases based on a quadratic function per meter, while the cumulative wear per meter increases linearly. Volumetric mass loss increases exponentially with the increase of surrounding rock strength and Cerchar abrasion index and decreases logarithmically with the increase of cutter life index. When the surrounding rock strength is constant, when the revolutions per minute, torque, thrust, and penetration per revolution increase, the cutter wear per meter changes following a quadratic function, which first increases and then decreases. With the increase of penetration rate, the cutter wear per meter changes as a quadratic function, first decreasing and then increasing. Cutter wear is most sensitive to cutter head torque and thrust. In order to reduce cutter wear, it is suggested that cutter head torque should be limited to the range 1100–1300 kN m or 2100–2400 kN m, and the thrust should be limited to the range 9500–11,000 kN or 15,500–16,000 kN.