Sliding Wear of Ni–17.5Si–29.3Cr Alloy under Water Lubrication

The tribological properties of Ni–17.5Si–29.3Cr alloy against Si₃N₄ under water lubrication conditions were studied on a ball-on-disc reciprocating 1tribotester. The effects of load and sliding speed on tribological properties of the alloy were investigated. The worn surfaces of the alloy were examined with SEM, TEM and an X-ray photoelectron spectroscope (XPS). It was found that the tribological properties of the alloy were closely dependent on the sliding conditions. Wear rate with the load of the alloy increased slightly at low and moderate load and increased dramatically at high load. Wear rate with the sliding speed of the alloy increased slightly at low and moderate sliding speed and increased dramatically at high sliding speed, which showed the same trend as that with the load. The friction coefficient increased with the load (especially at high load), and decreased with sliding speed at low sliding speed and increased significantly at high sliding speed. Wear mechanism of the alloy was mainly microploughing and delamination at low and moderate load and transformed to microfracture and delamination at high load.     

Dry Reciprocating Sliding Friction and Wear Response of WC–Ni Cemented Carbides

A number of WC–Ni based cemented carbide grades with distinctive binder contents were tested with the goal to evaluate their dry reciprocating sliding friction and wear behaviour against WC–6 wt.%Co cemented carbide using a Plint TE77 tribometer and distinctive normal contact loads. The generated wear tracks were analysed by scanning electron microscopy and quantified volumetrically using surface scanning topography. The experimental results revealed one WC–Ni grade with superior wear performance.     

Dry Sliding Friction and Wear Behaviour of an Electron Beam Melted Hypereutectic Al–Si Alloy

The economic and environmental benefits of using light-weighting technology in automotive applications continue to attract attention for feasible commercial solutions. This study investigates the use of pulsed electron beam melting of a hypereutectic Al–Si alloy as a possible modification procedure for cylinder crankcase bore facing surfaces. Machined surfaces of an A390 alloy were subjected to five pulsed electron doses with an applied cathode potential between 16.5 and 36 kV. It was found that increasing beam accelerating voltages led to an initial decrease (1.4 μm R _a) but subsequent increase (4.0 μm R _a) in average surface roughness values associated with surface crater formation due to sub-surface melting and eruption. Surfaces were tested under dry sliding tribological conditions against 52100 bearing steel in a reciprocating geometry. Average dynamic friction coefficients were higher (0.9) compared to the untreated alloy surface (0.6) as a result of a greater degree of adhesion to the counterface. However, FIB cross sections of worn surfaces indicated that this activated an oxidative type wear process which ultimately led to the formation of a beneficial surface tribo-film on the EBM-treated surfaces, improving the specific wear rates by up to 66%.     

Surface Roughness Effect on the Friction and Wear Behaviour of Acrylonitrile–Butadiene Rubber (NBR) Under Oil Lubrication

Tribology Letters - The artificial cervical disc was simplified and designed as a ball-on-socket model with the material configuration of polymer-on-Ti6Al4V (TC4). The material of polymer ball...     

Influence of Polyfluo-Wax on the Friction and Wear Behavior of Polyimide/Epoxy Resin–Molybdenum Disulfide Bonded Solid Lubricant Coating

Polyimide/Epoxy resin–molybdenum disulfide bonded solid lubricant coatings (denoted as PI/EP-MoS₂) were prepared. The influence of polyfluo-wax (denoted as PFW) on the microhardness and friction and wear behavior of as-prepared PI/EP-MoS₂ lubricant coating was measured using a microhardness tester and a reciprocating ball-on-disc tribometer, respectively. The worn surfaces of the lubricant coatings were observed with a scanning electron microscope, and their wear rate was determined with a Micro XAM surface mapping microscope. Moreover, the transfer films formed on the counterpart steel ball surfaces were analyzed by X-ray photoelectron spectroscopy. Results indicate that the incorporation of a proper content of PFW filler is effective at improving the antifriction performance of the PI/EP-MoS₂ lubricant coating while maintaining better wear resistance. Moreover, the friction coefficient of the lubricant coating decreases with increasing content of PFW from 2 to 10%, and the one with a filler content over 6% PFW has a steady friction coefficient of 0.07. The improvement in the antifriction performance of the lubricant coating with the incorporation of the PFW filler is attributed to the excellent lubricity of homogeneously distributed PFW.     

Dry Sliding Wear Behavior and a Proposed Criterion for Mild to Severe Wear Transition of Mg–3Al–0.4Si–0.1Zn Alloy

Wear behavior of Mg–3Al–0.4Si–0.1Zn alloy was studied as a function of applied load and sliding speed under dry sliding conditions using a pin-on-disk configuration within 20–380 N and 0.1–4.0 m/s. An empirical wear transition map has been constructed to delineate the conditions under which severe wear initiated. The roles of microstructural evolution, hardness change in subsurface and surface oxidation on wear transition were also studied. The results indicate that the transition to severe wear occurs when the deformed microstructure in surface layer of material transforms into dynamic recrystallization (DRX) microstructure. A contact surface DRX temperature criterion for mild to severe wear transition is proposed, and the contact surface DRX temperatures are calculated using activation energy obtained by hot compression tests. A model for predicating mild to severe wear transition load has been developed based on the proposed contact surface DRX temperature criterion. The mild to severe wear transition loads are well predicted within the sliding speed range of 0.8–4.0 m/s.     

Three-Body Abrasive Wear Behavior of Low Carbon Fe–B Cast Alloy and Its Microstructures Under Different Casting Process

This study investigates the effect of semi-solid processing on the microstructures, mechanical properties of low carbon Fe–B cast alloy. The as-cast microstructure of Fe–B cast alloy consists of the eutectic boride, pearlite, and ferrite. Compared with the coarse eutectic borides in the ordinary alloy, the eutectic boride structures in the semi-solid alloy are greatly refined. Moreover, the boride area fraction, Rockwell hardness, impact toughness, etc., before and after heat treatment under different casting methods are also investigated systemically. The wear behaviors of low carbon Fe–B cast alloy are studied by three-body abrasive wear tester. The wear weight loss of semi-solid Fe–B cast alloy is lower than that of the ordinary Fe–B cast alloy because of the lower average boride area for semi-solid specimen. Meanwhile, the wear mechanism of the low carbon Fe–B cast alloy under different casting process is depicted and analyzed by using the physical models.     

Effect of Aramid Pulp and Lapinas Fiber on the Friction and Wear Behavior of NBR Powder–Modified Phenolic Resin Composite

Short fiber reinforcement plays a definite role in governing the performance of a composite through the improvement of different material properties. The present investigation deals with the effect of aramid pulp and lapinas fiber on the friction and wear characteristics of a composite made from phenolic resin modified by powdered acrylonitrile butadiene rubber (NBR) on a pin-on-disc tribometer. Four composites, containing 10, 20, 30, and 40 wt% of aramid pulp with respect to phenolic resin content, were prepared. Another four composites, containing 50, 100, 200, and 300 wt% of lapinas fiber with respect to phenolic resin content, were also made. It was found that the two different fibers have distinctly different contributions to the friction and wear properties of the composites. It was also found that the incorporation of aramid pulp enhances friction stability of the composites much better than that of lapinas fiber. The change in surface morphology of these composites was studied by scanning electron microscopy (SEM) before and after the friction test. SEM images of friction samples containing aramid pulp corroborated the occurrence of wear through an adhesive wear mechanism, whereas the lapinas fiber–containing composites showed an abrasive wear mechanism.     

Effect of 10 wt% VC on the Friction and Sliding Wear of Spark Plasma–Sintered WC–12 wt% Co Cemented Carbides

The effect of 10 wt% VC addition on the friction and sliding wear response of WC–12 wt% Co cemented carbides produced by spark plasma sintering (SPS) was studied. The SPS of WC–12 wt% Co alloys with and without 10 wt% VC, at 1100 and 1130°C, respectively, yielded dense materials with minimal porosity. No eta phase was found in any of the alloys. The WC–12 wt% Co–10 wt% VC alloy showed the formation of a hard WV₄C₅ phase, which improved the alloy's hardness. Friction and dry sliding wear tests were done using a ball-on-disk configuration under an applied load of 10 N and sliding speed of 0.26 m.s^?1, and a 100Cr-steel ball was used as the counterface. A significant improvement in the sliding wear response of the harder and more fracture tough WC–12 wt% Co–10 wt% VC alloy compared to the WC–12 wt% Co alloy was found. Analysis of the worn surfaces by scanning electron microscopy showed that the wear mechanisms included plastic deformation, preferential binder removal, adhesion, and carbide grain cracking and fragmentation.     

Dry Sliding Friction and Wear Properties of Al–25Zn–3Cu–(0–5)Si Alloys in the As-Cast and Heat-Treated Conditions

Dry sliding friction and wear properties of ternary Al–25Zn–3Cu and quaternary Al–25Zn–3Cu–(1–5)Si alloys were investigated using a pin-on-disc test machine after examining their microstructures and mechanical properties. An alloy (Al–25Zn–3Cu–3Si), which exhibited the highest tensile and compressive strengths, was subjected to T7 heat treatment. Surface and subsurface of the wear samples were investigated using scanning electron microscopy (SEM). The hardness and both tensile and compressive strengths of the alloys increased with increasing silicon content, but the trend reversed for the latter ones above 3% Si. It was observed that T7 heat treatment reduced the hardness and both tensile and compressive strengths of the Al–25Zn–3Cu–3Si alloy, but increased its elongation to fracture greatly. Three distinct regions were observed underneath the surface of the wear samples of the Al–25Zn–3Cu–3Si alloy. The formation of these regions was related to the heavy deformation of surface material and mixing, oxidation and smearing of wear material. Al–25Zn-based ternary and quaternary alloys in both as-cast and heat-treated conditions were found to be superior to SAE 660 bronze as far as their mechanical and dry sliding wear properties are concerned.