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Molybdenum disilicide (MoSi₂) is considered to be a promising high temperature material for turbojet and hypersonic engines in aerospace and various industrial applications, because of a high melting point (2030°C), adequate density (6.3g/cm³) and an excellent oxidation resistance. Some researches on MoSi₂ have been carried out but the wear behavior of this material is seldom studied. This paper focused on the effect of sintering temperature of MoSi₂ on the wear behavior. MoSi₂ powder was evaluated from the variation of fabricating conditions such as preparation temperature 1250°C, 1350°C and 1500°C. Wear tests were performed with a sliding speed of 5.21mm/sec and a normal load of 8kgf. Each test was run over a period of 6 hours. The wear behavior is evaluated with respect to the hardness of materials. Hardness test was carried out with a Micro-Vickers hardness tester. As a result of the tests, the friction coefficient was decreased with the increasing sintering temperature of MoSi₂ but the friction coefficient did not vary much for all specimens at temperatures. Hardness values decreased with a decrease in sintering temperature because the indentation under a lower temperature probably contained more defects.

Dry sliding wear tests of hot-pressure sintered and wrought cobalt were carried out to compare their wear characteristics. Cobalt powders with average size of 1.5µm were electro-pressure sintered to make sintered-cobalt disk wear specimens. A vacuum-induction melted cobalt ingot was hot-rolled at 800°C to a plate, from which wrought-cobalt disk specimens were machined. The specimens were heat treated at various temperatures to vary grain size and phase fraction. Wear tests of the cobalt specimens were carried out using a pin-on-disk wear tester against a glass (83% SiO₂) bead at 100N with the constant sliding speed and distance of 0.36m/s and 600m, respectively. Worn surfaces, their cross sections, and wear debris were examined by an SEM. The wear of the cobalt was found to be strongly influenced by the strain-induced phase transformation of ε-Co (hcp) to α-Co (fcc). The sintered cobalt had smaller uniform grain size and showed higher wear rate than the wrought cobalt. The higher wear rate of the sintered cobalt was explained by the more active deformation-induced phase transformation than in the wrought cobalt with larger irregular grains.

The paper is focused on the wear mechanism of orbital forged and equal-channel angular extruded Cu OFHC (oxygen-free high thermal conductivity) material. The wear behaviour of the Cu OFHC material is investigated through pin-on-disc tests. Two different processing conditions have been used, equal-channel angular processing (ECAP) and orbital (radial) forging. The wear investigations in this orbital formed material are unique; additionally wear properties show interesting wear characteristics. Particular attention has also been paid to the friction coefficient and to the role of the wear rate.

Sliding wear and three-body abrasive wear characteristics of plain carbon steel (0.19C-0.72Mn) were compared to understand mechanisms of both wear in the steel. Microstructure of the steel was varied by heat treatments, and effects of microstructure as well as hardness on both wear were investigated. Dry sliding wear tests were carried out at room temperature using a pin-on-disk wear tester against AISI 52100 bearing steel. Three-body abrasive wear tests were performed using a ball-cratering abrasive wear tester employing angular SiC abrasives. The sliding wear proceeded with subsurface deformation and consequent fracture, while micro ploughing and cutting were major mechanisms of the abrasive wear. Hardness alone failed to characterize the sliding wear of the steel. Subsurface strain-hardening and uniform-deformation were principal controlling factors for the sliding wear, while hardness was the factor to control the abrasive wear of the steel under the given test condition.

This work is based on the dry sliding wear of NiCrBSi reinforced coating deposited on TA15 titanium alloy using the laser cladding technique, the parameters of which were such as to provide almost crack-free coatings with minimum dilution and very low porosity. SEM results indicated that a laser clad coating with metallurgical joint to the substrate was formed. Compared with TA15 substrate, an improvement of the micro-hardness and wear resistance was observed for this composite coating. Rare earth oxide Y₂O₃ was beneficial in producing of the amorphous phases in laser clad coating. With addition of Y₂O₃, more amorphous alloys were produced, which increased the micro-hardness and wear resistance of the coating.

The present research paperfocusses on manufacture of AlSi₆Cu₄–3 wt.% TiO₂ metal matrix composite (MMC) through liquid metallurgy route, and the manufactured composites are tested for their dry sliding wear behavior using response surface methodology (RSM). The extensive microstructural investigation is carried out to examine the dispersion of Titania particles, its bonding ability, and embedment characteristics with the matrix. The wear rate on the developed MMC is investigated and predicted using regression model. Further, the confirmation test is conducted to validate the model. The microstructures of the composite had revealed that TiO₂ particles are dispersed in the Al matrix. Further, the surface plots show that the wear rate started to vary linearly with the function of load whereas the wear rate starts to vary nonlinearly with the function of the sliding velocity and the sliding distance. In addition, the worn surfaces were investigated through the scanning electron microscopewhich addressed the wear mechanisms and revealed that TiO₂ particles enhance the wear performance of aluminum alloy by a reduction in material removal at all wear conditions.

In this study, NiCrC and NiCrSi coatings are deposited on the MDN 310 steel using High-Velocity Oxy-Fuel (HVOF) process. Laser Surface Melting (LSM) post-heat treatment is carried out on as-sprayed coatings using Laser Engineered Net Shaping (LENS^TM) with a power of 300W. The characteristics of both coatings in terms of mechanical and metallurgical properties have been investigated. The thicknesses of the as-sprayed NiCrC and NiCrSi coatings are in the range of 170–200$\mu$m. Laser-treated NiCrC and NiCrSi coatings exhibit a thickness range of 162–185$\mu$m, respectively. The microstructure of laser-treated NiCrC-300W coating clearly shows a dendrite-like structure, whereas the laser-treated NiCrSi coating exhibits hard layer and columnar homogeneity. Microhardness of as-sprayed NiCrC coating is $515\pm 15$${\text{HV}}_{0.3}$ and that of NiCrSi coating is $645\pm 25$ HV${}_{0.3}$. Microhardness of laser-treated NiCrC coating is $720\pm 30$ HV${}_{0.3}$ and that of NiCrSi coating is $890\pm 15$ HV${}_{0.3}$. Dry sliding wear tests are conducted at room temperature (RT) and 400^∘C with 10-N and 20-N loads. The wear rates at 400^∘C temperature of laser-treated NiCrC and NiCrSi coatings produced are slightly below $(1-2.2)\times 10^{-3}$mm³/m and $(0.8-1.6)\times 10^{-3}$mm³/m, respectively. Laser-treated coatings produced better dry sliding wear behavior compared with as-sprayed coatings owing to dense microstructure. Formation of SiC phase in NiCrSi coating imparts high wear and frictional resistance compared to the NiCrC coating.

In water cooled reactors, the friction between spacer grid and fuel rod can lead to severe wear and it is an important topic to study. In the present study, sliding wear behavior of zirconium alloy was investigated in water and dry state using the pin-on-disc sliding wear tester. Sliding wear resistance of zirconium alloy against heat treated inconel alloy was examined at room temperature. The parameters in this study were sliding velocity, axial load and sliding distance. The wear characteristics of zirconium alloy was evaluated by friction coefficient, specific wear rate and wear volume. The micro-mechanisms responsible for wear in zirconium alloy were identified to be micro-cutting, micro-pitting, delamination and micro-cracking of deformed surface zone.

This study investigates the microstructure and sliding wear behavior of AM60 alloys with different amounts of lanthanum and cerium mixed rare earths added(0, 0.5, 1, 1.5, and 2 wt%). The microstructure observation and EDS analysis demonstrated that adding La and Ce in AM60 alloy resulted in the formation of a new phase Al₁₁(La, Ce)₃ and minimized the precipitation of Mg₁₇Al₁₂ phase. The grain size was refined. The worn surface was covered with long continuous grooves parallel to the sliding direction. AM60 alloys with La and Ce added had a lower wear rate and friction coefficient than AM60 alloys without La and Ce addition. This is attributed to the formation of uniformly distributed, finer and hardxer Al₁₁ (La, Ce)₃ precipitates. The hardness and wear resistance of AM60 alloy were observed to peak at 1 wt. % La and Ce.

Dry sliding wear tests of hot-pressure sintered and wrought cobalt were carried out to compare their wear characteristics. Cobalt powders with average size of 1.5µm were electro-pressure sintered to make sintered-cobalt disk wear specimens. A vacuum-induction melted cobalt ingot was hot-rolled at 800°C to a plate, from which wrought-cobalt disk specimens were machined. The specimens were heat treated at various temperatures to vary grain size and phase fraction. Wear tests of the cobalt specimens were carried out using a pin-on-disk wear tester against a glass (83% SiO₂) bead at 100N with the constant sliding speed and distance of 0.36m/s and 600m, respectively. Worn surfaces, their cross sections, and wear debris were examined by an SEM. The wear of the cobalt was found to be strongly influenced by the strain-induced phase transformation of ε-Co (hcp) to α-Co (fcc). The sintered cobalt had smaller uniform grain size and showed higher wear rate than the wrought cobalt. The higher wear rate of the sintered cobalt was explained by the more active deformation-induced phase transformation than in the wrought cobalt with larger irregular grains.