Papers by Keyword: Wear

Abstract: The use of silica sand tailings without leaching as a reinforcement in the development of composites remains a material class known for outstanding properties. However, owing to the availability, least expensive, and physical properties of silica beach sand, this study investigates the effect of non-leached silica (SiO₂) beach sand particulates on the mechanical and tribological characteristics of aluminium (Al) alloy matrix composites. In the study, an AA6061 alloy matrix was reinforced with varying content of SiO₂ beach sand (0, 20, 30, and 40 wt%) using the stir casting process. The SEM results revealed uniform dispersion of the beach sand particulates in the resultant composites with minimal agglomerations up to 30 wt% loading. Thus, the hardness and elastic modulus of the SiO₂/AA6061 alloy composites were improved by 326.7% and 90.9%, respectively, at 30 wt% SiO₂ particle addition. In addition, with the introduction of the SiO₂ particles in the alloy matrix, a reduction in the coefficient of friction by 24.5% and wear rate by 40.79% was recorded compared to the pure Al alloy. These findings indicate the substantial potentiality of silica beach sand particulates reinforced Al alloy matrix composite material as a promising candidate for mechanical load bearing, frictional components, and high-performance engineering applications including construction, automotive component, airframe, marine and rail transport.

Abstract: This study aims to investigate the wear behavior of AA7075 alloy with the reinforcement of Silicon carbide (SiC) and Boron carbide (B4C) particles. Process parameters are crucial for component quality improvement, particularly in metal matrix composites (MMCs), a unique class of materials used in a variety of technical applications, such as but not limited to automobiles, marine, and aeronautics.These are frequently utilized in challenging applications due to their significantly better strength to weight ratios, stiffness, and then standard materials. However, it has numerous disadvantages, including high weight ratios, high deformation and stresses, poor fatigue life cycle, early wear and friction, and so on. Up till now, numerous reinforcements have been employed to address these crucial problems. Due to its superior properties, aluminum matrix composites (AMCs) have been used in many different applications. This work attempts to examine the wear behavior of AA7075 alloy reinforced with silicon (SiC) and boron (B4C) particles utilizing the stir casting process AA 7075-(SiC)-(B4C) composites were produced by employing AA 7075 as the matrix material with silicon carbide (SiC) and boron carbide (B4C) particles as reinforcement in various percentages of weight (5%, 10%, and 15%). Parameters of the composites, including wear behavior, coefficient of friction, frictional force, and pin temperature were assessed through graphical representation.

Abstract: Gray cast iron has been one of the most widely used engineering materials since a long time ago. However, the development of casting techniques and methods to produce various models of cast iron products for the domestic market is not followed by improvements in product quality. The intriguing aspect of gray iron products is the diverse morphologies that graphite can assume, leading to distinct variations in mechanical and physical properties. Quenching is a typical heat treatment procedure performed to improve the mechanical properties of a material that entails the rapid cooling of the material from a high temperature to a low temperature. The aim of this study is to investigate the effect of water quenching effects on microstructure, crystal structure, hardness, and wear of gray iron, which undergoes quenching from the austenitizing temperature. Gray cast iron was obtained from the local foundry industry, then thermally treated at 900°C, held for 15 minutes, and rapidly quenched by water. The quenching procedure induces a significant alteration in the overall microstructure, where transition of most dendrite arms to the eutectic phase microstructure is observed. Moreover, the quenching process is attributed to the reduction of crystal size and growth of carbon crystal. The average crystal size of the sample was reduced from 47.833 nm to 17.97 nm, hence improving the hardness from 16.375 HRC to 48.04 HRC, which in turn improved wear resistance under high loading condition from 0.014 g/sec to 0.00042 g/sec.

Abstract: The chemical composition of the metal and carbide phase, hardness, and common mechanical properties of cast iron, ICH28H2 cast iron, a type of high-chromium white cast iron, and the dependence of hardening, annealing, and tempering process types were studied. Therefore, annealing and hardening heat treatments were employed, and the results were compared to measurements in the as-cast state. The metal matrix exhibited content within the range of 16.8% to 19.7% Cr and 71.9% to 76% Fe, while the carbide phase showed 63.4% to 64.7% Cr and 23% to 24.8% Fe. The Cr carbide in high Cr white iron primarily appeared as (Fe, Cr)7C3 type, leading to the calculated chemical formula of the eutectic carbide as (Fe2Cr5)C3. The as-cast white iron displayed a hardness of 53 HRC, which increased marginally to 56.2 HRC after hardening. This suggests that the 28% Cr white iron alloy does not exhibit a significant hardness enhancement compared to the cast state, attributed to its high Cr content. The hardness of the metal phase directly influences the overall hardness change of the alloy, while the carbide hardness is dependent on its Cr content. Abrasive wear studies revealed that 28% Cr white cast iron exhibited superior wear resistance in the as-cast state compared to the hardened state, aligning with research indicating that cast iron demonstrates optimal wear resistance in its cast state.

Abstract: Maintenance due to the replacement of damaged wheels and rails due to rolling contact fatigue (RCF) and wear has been found to be the major problem to rail operating companies. This problem tends to lead to unavailability of railway networks. To solve this problem, costly wear simulators are developed to predict the wear behaviour of the rails and wheels to improve the preventive maintenance in pursuit of operational efficiency. Therefore, more studies that simulate a combination of rolling and sliding wear, together with RCF, are required, specifically for the Southern African, where good and cost-effective rail wear simulators are not readily available. The problem with wear and RCF simulators is high production costs, so this work aims to solve this problem by developing a cost-effective wear test rig that is capable of simulating RCF, sliding and rolling wear as experienced by the train wheel while moving along railway tracks. For this work, it was decided that twin-disc concept would be used, since literature clearly shown that the method was able to simulate the three damage mechanisms mentioned. The developed twin-disc wear simulator was able to simulate both rolling and sliding wear and parameters including contact load and slip ratio could be changed with ease so to simulate the actual contact conditions between the wheel and rail. Outputs such as coefficient of friction and wheel disc temperature were obtained. The results showed that the severity of wear is heavily dependent on slip ratio i.e., increased with slip ratio, with both coefficient of friction and wear rate increasing with slip ratio.

Abstract: Wire-arc additive manufacturing is a method of 3D printing metal using welding techniques. However, due to heat, the mechanical properties of the deposited material may be affected. Various methods have been proposed to mechanically improve the properties. In this study, cold deformation was introduced to enhance the properties. The effects of a few parameters, including welding speed, wire feed rate, heat input, thickness ratio, and types of material, were studied. Based on the result, the hardness, tensile, and wear properties of the manufactured part improved, while other properties, like impact toughness, had a lower value. Based on the preliminary result, cold deformation shows potential alternatives for part repair or reconstruction of worn or broken parts.

Abstract: Ti₄₈Al₄₈Cr₂Nb₂ intermetallic alloy was studied for its tribological properties. The as-received TiAl alloy was prepared by spark plasma sintering (SPS) at 1200 °C for 5 and 7 min using 50 and 100 °C/min heating rates. Wear tests were done on the sintered TiAl under 10 N at room temperature in air. Results showed that an increase in relative density and superior microhardness led to a reduced material loss in the sample sintered for 7.5 min using a 100 °C/min heating rate. Scanning electron microscopy (SEM) images of the worn surface showed the wear widths and wear marks on the surface of TiAl alloy. The wear track width indicated the degree of wear, and the samples sintered for 7.5 min using a 100 °C/min heating rate showed improvement in wear resistance.

Abstract: Titanium and its alloys have a wide range of applications in various industries, including medicine. However, the low strength and high friction coefficient hinder their development in contact friction due to fretting fatigue. Among many factors, structure refinement, temperature and amplitude are the most responsible for fretting wear of structural materials. The purpose of the article is to investigate the effect of displacement amplitude, size of grain and test temperature on the fretting wear of the pure titanium in coarse-grained and ultrafine-grained states. It is shown that an increase in the test temperature for both structural states leads to a multiple increase in wear. Structural refinement of titanium to hundreds of nanometers helps to reduce wear at room and elevated temperatures.

Abstract: Asbestos-based brake shoes are being faded out due to worries that they may cause cancer; as a result, research for suitable replacements is an essential area of focus. Research on agricultural by - products such as flax fibres, rockwool, aramid fibres, banana fibres, and nut shells from palm trees have been used to develop a number of potential replacements for asbestos. Palm wastes, which are picked for the study since there was a paucity of previous research on the topic, are obtained from agricultural waste fibres. As part of this investigation, a composite material was created, and a number of tests were carried out in order to investigate the wear and durability of a set of unique composites. The novel composites contained 20% epoxy resins, 10 % carbon, 15% CaCO₃, 30–45% PKS, and 10–25%Al₂O₃ respectively. The results obtained showed that the finer the sieve size the better the properties.

Abstract: The technology repair and restoration dies for hot punching is considered. During the overhaul the hammer die, a layer of metal is removed from the side the mirror to the entire depth the cavity of the stream, then the figure the new stream is marked, and then the stream is milled as in a new punch. Sometimes such methods restoring punches as electric arc surfacing welding or deformation with a special punch in the form of a stream are used. When installing inserts in a punch, it is necessary to compensate for the removed metal layer with special linings. Welding electrodes must be selected depending on the requirements for the base metal and service properties the deposited layer – hardness, heat resistance, allowable specific pressures, machinability, heat treatment acceptance, etc.