Surface Wear Rate Research Articles

Wear and thermal resistance properties of aluminium particulate microcomposites

Wear resistance and thermal stability are not fundamental properties of materials, but their effects are inevitable in applications involving two-body contact because of friction-induced wear and heat. Wear resistance and thermal stability of epoxy containing 10% by weight of 66.34 μm aluminium particles were examined using mass loss per sliding distance approach and glass transition temperature (Tg) was used as a parameter for thermal stability. The results obtained revealed a reduction in the wear rate due to addition of aluminium particles. About 62, 58 and 39% reductions at 9 N/0.65 m s−1; 9 N/1.3 m s−1 and 25 N/1.3 m s−1, respectively imply that both sliding speed (v) and the applied load (F) contribute to an increase in the wear rate. A lower coefficient of friction of epoxy aluminium composites signifies lower surface wear rate in comparison with that of the epoxy polymer upon contact with another body in applications. The linear model establishes that v with a P value of 0.0046 has a greater significant influence on the wear resistance of the composite than F with a higher P value (0.0103). By the model, the epoxy aluminium composite under 24.63 N is expected to experience a wear rate of 0.000537 g m−1 which is 1380% lower than that established by the results of the experiment. About 36% increase in Tg is observed and 2FI model affirms that there is a gradual increase in Tg with heat flow through the sample during the glass transition period. Hence, the 2FI model having adequate precision of 164 > 4 is appropriate to be used for navigating a design phase for thermal stability properties.

Wear life prediction of cemented carbide microtextured surface

In the study of metal surface friction, microtextured surfaces have been shown to reduce the surface friction coefficient, However, the influence of microtexture preparation parameters on its surface wear rate is rarely considered. In this paper, the effects of microtexture preparation parameters were studied by detecting elements in the area around the microtexture. Through friction experiments, the relationship between different microtexture preparation parameters and the surface wear rate of cemented carbide was studied. After three stages of experiments, it is concluded that the laser power has an important effect on the surface wear rate of microtextures. In addition, the interaction between laser power and microtexture diameter has a great effect, but gradually decreases with increasing friction distance. Finally, a wear prediction model for carbide microtextured surfaces with different preparation parameters was established, the results can provide a reference for the application of microtextured surfaces in cutting tools.

Microstructure and wear behavior of mechanically alloyed powder AlxMo0.5NbFeTiMn2 high entropy alloy coating formed by laser cladding

High entropy alloys (HEAs) is a newly wear-resistant material with multi-component structures of equal or near equal ratio. The tensile strength of pure Al is one fifth of the low carbon steel. After heat treatment and alloying, the strength will be greatly increased. Al alloys have good machining performance. The secondary and bending machining are also easier to obtain. To strengthen the wear resistance and hardness of normal steel tools, AlxMo0.5NbFeTiMn2 (x = 1, 1.5, 2) HEA coatings are experimentally manufactured in a systematic approach to complete existing results and prove an effective method of HEA coating preparation by laser cladding. The powders were first mechanically alloyed by a high-energy rod mill to ensure the homogenization of the structure. The structural characteristics were studied by XRD measurement, resulting in the crystal structure and its role in the HEA sample can be determined. Phase composition determined by electron microscope measurement (EDS, EBSD and TEM). It was found that their appearance, composition and contribution in the studied HEAs depended on the Al content. The phase composition of the coating consists of body-centered-cubic solid solution as well as (Nb, Ti)C carbides. As a result, the Al2Mo0.5NbFeTiMn2 HEA coating shows the highest microhardness and most excellent wear resistance of all tested coatings. Compared with the substrate, this indicates the smoother worn surface and lower volume wear rates can be concluded with Al addition in HEA coatings. It is assumed to be promising for a fusion alloy progress standpoint.

Surface Wear Anisotropy in AlSi10Mg Alloy Sample Fabricated by Selective Laser Melting: Effect of Hatch Style, Scan Rotation and Use of Fresh and Recycled Powder

AbstractAdditive manufacturing (AM) has witnessed substantial growth in recent years due to its excellent manufacturing capabilities and innovative production methodologies. However, the mechanical suitability aspect in terms of material wear has not received much attention yet and needs rigorous assessment. This study investigates the wear anisotropy in an AlSi10Mg alloy sample fabricated by selective laser melting (SLM) technique. Different scanning strategies encompassing the island and the continuous scanning patterns were used in sample manufacturing. The effects of the scanning vector orientation, design pattern, and the island pattern size on the mechanical wear and wear anisotropy have been analyzed in detail. The study also focused upon a comparative investigation of the wear properties at the top and the side surfaces to understand the wear anisotropy in different directions. The samples are fabricated both by the fresh and the recycled powder and the role of powder state is described. The ball-on-disk test is performed to simulate the similar contact applications for marine/automotive components such as bearings. Bearing steel balls are used as a standard sliding counterpart material to investigate the wear properties. The wear microstructure is analyzed by scanning electron microscopy. Overall, the island strategy with 2 mm hatch style and 45 deg scan rotation have achieved better wear resistance and friction coefficient compared with the continuous hatch style. The wear behavior is found to be anisotropic. The Raman spectra validate the presence of silicon and carbon particles on the wear track, which have a significant effect on the tribological properties. The type of particles present in the sliding zone characterizes different wear stages. Wear mechanism is described by considering four parameters, namely, scan pattern, scan vector rotation, type of powder, and the wear measurement direction. Results show that the surface wear rate of samples made by the fresh powder is lower than the recycled powder. However, samples of the recycled powder have friction modifier characteristics. The best wear rate and friction coefficient values are obtained with the island strategy (2 mm hatch, 45 deg scan rotation) in the side plane and are 3.76 × 10−6 mm3/N m, 0.0781, respectively.

Prediction and optimization of performance measures in electrical discharge machining using rapid prototyping tool electrodes

In this work, the performance of rapid prototyping (RP) based rapid tool is investigated during electrical discharge machining (EDM) of titanium as work piece using EDM 30 oil as dielectric medium. Selective laser sintering, a RP technique, is used to produce the tool electrode made of AlSi10Mg. The performance of rapid tool is compared with conventional solid copper and graphite tool electrodes. The machining performance measures considered in this study are material removal rate, tool wear rate and surface integrity of the machined surface measured in terms of average surface roughness (Ra), white layer thickness, surface crack density and micro-hardness on white layer. Since the machining process is a complex one, potentiality of application of a predictive tool such as least square support vector machine has been explored to provide guidelines for the practitioners to predict various machining performance measures before actual machining. The predictive model is said to be robust one as root mean square error in the range of 0.11–0.34 is obtained for various performance measures. A hybrid optimization technique known as desirability based grey relational analysis in combination with firefly algorithm is adopted for simultaneously optimizing the performance measures. It is observed that peak current and tool type are the significant parameters influencing all the performance measures.

Transitioning the total hip arthroplasty technique from posterior approach in lateral position to direct anterior approach in supine position-risk factors for acetabular malpositioning and the learning curve.

Cup positioning is important for optimum hip stability, avoiding component impingement and decreasing both bearing surface wear and revision rate. Transitioning from posterior approach in a lateral position to direct anterior approach (DAA) in a supine presents unique challenges for surgeons. The aim of this study was to examine the learning curve when using standard instrumentation that was not specific to DAA. A consecutive retrospective series of 537 total hip arthroplasty by DAA from May 2013 to December 2017. Cup positioning was analysed on radiographs and classified whether inside or outside two safe zones (inclination 30-50° and anteversion 10-30°). The demographic data (age, BMI, gender, neck shaft angle (NSA)), surgeon's dominant side and experience were assessed as risk factors. Eighty per cent of cups (n = 426) were in the combined safe zones. Eighty-eight per cent (n = 470) were in appropriate anteversion and 87% (n = 463) abduction. Two factors that were significant were identified: Cups of left hips operated by right-handed surgeons were more anteverted (OR = 4.06) and more vertical (OR = 2.23); females had a higher anteversion of the cup (OR = 2.42). Obesity, age and NSA were not risk factors for cup malposition. There was a spike of cups too horizontal at the beginning of the experience (OR = 3.86), and no learning curve was observed in the other orientations. With our DAA technique using standard instrumentation, there were no risk factors linked to the patient identified for cup malposition. DAA-specific instrumentation is not required to achieve optimum positioning of the cup. Surgeon has to be aware of an excess of abduction at the beginning of his experience and an excess of anteversion and adduction when performing THA on the opposite side of his dominant hand.

An investigation on the microstructure, wear rate and hardness of Surface alloying Ni-Hard 4 cast iron with Tungsten Using GTA

Ni-Hard 4 cast iron is a special grade alloy and its extensively used in the field of concrete mixer blade, mining, turbine fittings etc. The investigation of surface modification process (SMP) on microstructure, wear rate and hardness of Ni-Hard 4 cast iron alloyed with tungsten was performed using gas Tungsten arc source. The grain structure was refined in the modified layer. The hardness was measured and it was found to be increased from 597 HV for the substrate to 1738 HV in the modified layer. Wear rate was 4.3 x 10 -3 mm 3 /m for the substrate and 0.21 x 10 -3 mm 3 /m in the modified layer. The wear was calculated using the weight loss of the specimen. The phase formation in the modified layer was observed by XRD analysis. From the elemental composition analysis, the presence of tungsten was observed to be 5.21 wt. % on an average. The test was performed in several locations in the modified layer for the elemental composition. So the investigation of this experiment to improve the surface properties of Ni-hard 4 cast iron used in the field of mining area.

Experimental investigation on the effects of aqueous solution in electric discharge machining

The aqueous solution of organic compound plays a crucial role as a dielectric medium in Die sink electrical discharge machining process. Two-phase of the dielectric medium, deionised water and aqueous solution of deionised water and glycerin, used in EDM. It eliminates hazards problem. The machining efficiency increases with the concentration of an organic compound in the aqueous solution at long pulse and discharges current compared to the deionised water. The working dielectric medium consists of deionised water and an aqueous solution of deionised water and glycerin. A constant gap voltage used to prove a constant spark gap in the dielectric medium. The drawback rough surface and relative high wear rate are considered at high discharge current in a straight polarity working condition. A regression equation and mathematical modelling used to optimise the process parameters in the investigation. This also reveals the dielectric medium with high viscosity has better machining performance that low viscosity medium.

Microstructure and Wear Properties of Mechanically Alloyed Powder Al <sub>x</sub>Mo <sub>0.5</sub>NBFeTiMn <sub>2</sub> High Entropy Alloy Coating by Laser Cladding

High entropy alloy (HEA) is a newly wear-resistant material with multi-component structure of isotonic or near-isotonic. To improve the wear resistance and hardness of base metal, the mechanically alloyed AlxMo0.5NbFeTiMn2 (x=1, 1.5, 2) HEA coatings are fabricated via laser cladding. The phases, microstructures, nanoindentation and wear behavior were investigated. As a result, more excellent wear resistance of AlxMo0.5NbFeTiMn2 than the BM and the Al2 HEA coating shows the highest hardness of all tested coatings. This indicates the smoother worn surface and lower volume wear rates with Al addition. It is assumed to be promising for a fusion alloy progress standpoint.

Improvement in hardness, wear rate and corrosion resistance of silicon bronze using gas tungsten arc

This study examines the effects of Gas Tungsten Arc (GTA) modification of silicon bronze alloy on the microstructure of the alloys and their surface properties, viz., hardness, wear rate and corrosion resistance. The substrate was modified at three different heat inputs in either argon or nitrogen atmosphere. It is observed that modification in nitrogen atmosphere causes enhanced heat transfer to the substrate, resulting in improved hardness, depth of penetration and decreased wear rate, compared to that under argon atmosphere followed by quick solidification. Modification under nitrogen environment resulted in ∼60% reduction in corrosion rate, with evidence of significant localized corrosion. Thus, it may be concluded that surface modification of silicon bronze alloy by GTA results in finer grains, increased surface hardness, decreased wear rate and improved corrosion resistance.

A new method for testing polymer gear wear rate and performance

This paper provides details of a new test rig design and methodology intended for, and successfully applied to, measuring the gear wear rate and performance of polymer composite gears under both dry and lubricated conditions. One of its unique contributions is that it continuously measures the gear wear rate, a feature essential for understanding polymer gear behaviour. While sharing some concepts with the traditional back-to-back test configuration used for steel gears, the new method introduces a rotary freedom to the block supporting the polymer gears under test. This block rotates if the gear tooth thickness is reduced, which aids control of the test load. The gear surface wear rate is recorded continuously by using a capacitance transducer to measure the pivot block motion. A second unique contribution of the new test method involves splitting the support block so that controlled misaligned gear engagements (not reported in other designs) can be introduced and subsequent changes to wear behaviour studied. The paper first outlines the test rig concepts and design before discussing in more detail the gear wear rate measuring principles, the methods of centre distance adjustment and the achievement of virtually constant gear loading. Finally, a selection test results are presented in summary to further validate the new test method and illustrate potential applications.

Modifying the surface of a titanium alloy with an electron beam and a-C:H:SiOx coating deposition to reduce hemolysis in cardiac assist devices

The use of implantable mechanical pumps to support stable heart function saves lives to a large number of patients. The priority goal of research in this area is to develop advanced pumps that will ensure minimal injuries and fractures of blood cells. A combined method of modifying the surface of disk pump parts made of titanium alloy VT-6 has been developed to reduce blood hemolysis. The method includes material pretreatment with a high-current low-energy electron beam and plasma-enhanced chemical vapor deposition of a-C:H:SiOx coating. The effect of such electron beam parameters as the energy density and the number of pulses on the surface morphology, hardness, plasticity index, friction coefficient and wear rate of the titanium alloy was studied. The effect of the 1.6-μm-thick a-C:H:SiOx coating on the surface morphology, mechanical and tribological properties of VT-6 samples subjected to preliminary electron beam processing was also investigated. Parts of the disk pump were modified according to the proposed technology and pump was tested on the degree of red blood cell destruction. After modifying the surface of pump parts, the destruction of red blood cells did not occur during the 4-h experiment, unlike a similar pump without surface modification. It is shown that the physical properties of the surface are one of the most important factors affecting hemolysis in mechanical pumps to support stable heart function.

Abrasive wear characteristics of 40Mn2 steel in simulated condition of sprocket wheel in crawler bulldozer walking system

The abrasive wear characteristics of 40Mn2 steel be studied in this paper. The rubber wheel abrasive wear tester be used for simulating the sprocket wheel working-conditions. The relationship between worn surface residual stress and wear rate was studied. Wear surface morphology and mechanism worn surface micro-structures are also shown in results. In addition, there are XRD pattern of the experimental abrasives, to better reveal the abrasive wear mechanisms. The results indicates that the larger the applied load and sliding speed is, the greater the wear rate will be. The content of hard phase in abrasive determine the wear rate. The main wear mechanisms of soil and coal in working-conditions are scratching and spalling, respectively. Spalling, chipping, scratching and pitting are the main wear mechanisms in sand working-condition. There are same trend of the wear rate and the worn surface residual stress with the wear time increasing. Intergranular carbides can decrease the wear resistance to some extent.

Anisotropic microstructure evolution of an AZ31B magnesium alloy subjected to dry sliding and its effects on friction and wear performance

Due to their hexagonal closed-packed (HCP) crystal structure, magnesium (Mg) and its alloys typically exhibit strong plastic anisotropy which gives rise to their orientation-dependent mechanical properties. Tribological performance in terms of friction and wear is of critical importance to manufacturing and applications of Mg alloys, particularly for components subjected to sliding motion. However, anisotropic microstructure evolution of Mg alloy and its effects on friction and wear properties have rarely been investigated. In this study, the orientation-dependent microstructure behaviors of an AZ31B Mg alloy during dry sliding were investigated. The coefficient of friction (COF) and wear rate of worn surfaces were analyzed and compared. The results indicated pronounced anisotropic friction and wear behaviors. The mechanism responsible for the anisotropic tribological behaviors was discussed.

Improving scratch-resistance and wear-resistance of VN film by deep cryogenic treatment with liquid nitrogen

ABSTRACTDeep cryogenic treatment is an effective method to improve materials’ properties and has shown a considerable industries application prospect. In this work, deep cryogenic treatment with liquid nitrogen had been applied to deal with multi-arc ion-plated VN film. The results show that after deep cryogenic treatment, the scratch-resistance and wear-resistance of VN film are improved greatly, but the improvement in properties as well as surface roughness evolution is not proportional to the soaking time. The VN film with a soaking time of 20 h has the best mechanical properties, and the VN film with a soaking time of 40 h has the finest scratch-resistance, while the VN film with a soaking time of 30 h has the lowest surface roughness and wear rate. However, the wear mechanisms of these VN films with different soaking time are all adhesive wear and oxidative wear.

Effect of Machining Parameters on Tool Wear and Surface Roughness In Dry and Wet Machining of Aisi 316 Austenitic Stainless Steel by Taguchi Method

Stainless steels are widely used to manufacture mechanical components due to excellent mechanical properties. Machining is considered as one of the most critical manufacturing processes in mechanical industry to produce desired shapes and dimensional accuracy of the components. It also affects the performance of the components in its functional requirement. This paper deals with the optimization of cutting parameters in machining operation for AISI 316 austenitic steel with dry and wet environment conditions. The chosen machining parameters in this research are cutting speed, feed rate, and depth of cut as input variables, whereas the response factors are surface roughness and wear rate. Taguchi method with the L9 orthogonal array was used to analyze the process parameters based in dry and wet machining conditions. The Taguchi approach provides the best setting with lower values of surface roughness and wear rate. The regression analysis is performed to obtain a mathematical model of responses in terms of the process parameter. The composite regression optimization gives best setting for dry condition (cutting speed 173 rpm, feed 0.25 mm/rev, and 0.87 mm of the depth of cut) and for wet condition (cutting speed 173 rpm, feed 0.3 mm/rev, and 0.57 mm of the depth of cut). The results show that surface roughness and wear rate are lower in the wet environment than the dry environment.

Effect of fretting damage on characteristics of high strength bearing steel up to very high cycle fatigue

The fretting fatigue behaviour of SAE 52100 bearing steel has been investigated up to very high fatigue cycles. The fretting fatigue strength was found to be markedly lower than the plain fatigue strength of the alloy. The fatigue strength reduction is higher in very high cycle fatigue regime which varies with fretting contact load. The fretting fatigue life is restricted in high cycle fatigue regime when the contact load is higher than the critical one. The rate of fretting damage growth influences the fretting fatigue life in very high cycle fatigue regime. The specimens with lower surface wear rate acquire higher fretting fatigue life by impeding the increase of fretting damage size.

Effects of sputtering gas on microstructure and tribological properties of titanium nitride films

Abstract Titanium nitride (TiN) films can be utilized as hard and protective coatings for synchronizer ring, which is the key components of the car gearbox. The tribological properties of synchronizer ring play a key role in the safety and reliability of the car shifting system. The aim of the present work is to improve tribological properties of synchronizer ring and investigate effects of depositing gas on preferred orientation, surface morphology, surface roughness and tribological properties of TiN thin films. The as-prepared films are deposited on copper alloy (TL084) and Si (100) substrates by a closed field unbalanced magnetron sputtering system. The different sputtering gas with the volume ratio of argon to nitrogen of 1:3, 1:2 and 1:1 is employed. Results indicated that the increasing argon concentration in the gas mixture promotes the growth of TiN nanocrystallines and reduces its surface roughness, friction coefficient and wear rate. TiN films have the (200) preferred orientation at low argon concentration, while the (111) preferred orientation dominates at high argon concentration. TiN thin films deposited with the ratio of argon to nitrogen of 1:1 has the best tribological properties, which are the best sputtering condition as an ideal functional coating for synchronizer ring.

Coupling transient mixed lubrication and wear for journal bearing modeling

Abstract A transient Mixed Lubrication-Wear coupling model (MLW coupling model) is developed to investigate the mixed lubrication and wear performances of journal bearings, and a wear experiment for journal bearing is performed to support the validity of the developed numerical model. In the coupling numerical model, the transient interaction between the behaviour of mixed lubrication and wear is considered by incorporating the wear depth distribution, which is determined by the developed friction fatigue wear model, into the film gap equation. The evolutions of the worn surface profile, wear rate, fluid pressure and asperity contact pressure over operating time are calculated by the developed numerical model. The simulated results demonstrate that the transient wear process affects the distribution trend of lubrication performances significantly, and a worn surface profile may exist that provides an optimal tribology performance of journal bearings. The simulated results also demonstrate that there are two wear stages, identified by initial and steady wear stage, of journal bearings under mixed lubrication condition. Furthermore, the effects of the input parameters, including the radius clearance(C), surface roughness (σ), asperity curvature radius (β) and boundary friction coefficient(μc), on the predicted mixed lubrication and wear performance are evaluated.

The mixed regime and wear mechanism of elliptical contact in the start-up process considering interface material properties: A theoretical prediction

Abstracts The start-up motion is the significant process of many mechanical applications especially for high-frequency start-stop equipment; the formation of separating film and the main wear approximately occur in this process. In this paper, the improved mixed algorithm and a new methodology of describing Gaussian rough surface are developed and theoretically validated based on Stribeck curve. Furthermore, the transient film formation of smooth contact and rough contact with the start-up motion is analyzed and validated. Finally, the wear mechanism of different friction pairs is investigated, meanwhile, the applicability of Evans model and Archard model is evaluated. Results show that the contact ratio of smooth contact is considerably large but the transition time is much short in comparison with rough contact because the valleys of rough surface conserve lubricant avoiding solid contact. Combining the Evans equation and this mixed technique, the wear volume and wear rate were successfully calculated. The type of friction pair influences greatly the wear volume and wear rate of contact surfaces. The wear volume and wear rate of TiN–TiN the minimum in the start-up process, and alumina ceramics with satisfactory fracture toughness is a potential coating that can be applied to mechanical elements with a wide range of slide-roll ratio.