排序方式: 共有6条查询结果,搜索用时 15 毫秒
1
1.
Jose Daniel B. de Mello Karyne C. Juste Philippe Kapsa Cristiano Binder Aloisio N. Klein 《摩擦学汇刊》2018,61(3):560-568
Recently, we presented the tribological evaluation of self-lubricating sintered steels produced by taking advantage of the powder injection molding process, the recently introduced plasma-assisted debinding and sintering process, and the in situ formation of solid lubricant particles. This new processing route promotes the in situ generation of nanostructured turbostratic graphite particles during silicon carbide dissociation. In this work, we present the influence of surface finishing on the tribological behavior of self-lubricating composites sintered at 1150°C with (3 and 5 wt%) and without SiC additions. We discuss the effects of the surface topography (Ra) on the friction coefficient and wear rates of specimens and counterbodies. The tribological behavior was analyzed using linear reciprocating sliding tests (constant load of 7 N, 60-min duration). It was shown that the reduction in surface roughness increased both the friction coefficients and wear rates of specimens and counterbodies, probably due to plastic deformation and consequent graphite reservoir sealing. Chemical analyses of the wear scars using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis showed a tribolayer that was composed predominantly of carbon and oxygen. Analyses of the wear scars showed traces of plastic deformation on both samples and counterbodies and the predominance of abrasion as the main wear mechanism. 相似文献
2.
Hot pressed silicon nitride that was exposed to high (90%) and low (32%) relative humidity was examined in ball-on-disc geometry against cemented carbide ball at various normal loads. The study indicated that Si3N4 tested at high R.H. gave less specific wear rate compared with Si3N4 at low R.H. The friction coefficient of Si3N4−WC-6% Co tribopairs was found in the range of 0.32–0.39 and 0.05–0.17 at low humidity and high humidity respectively. It is suggested that adsorbed moisture markedly affected the wear and friction properties of silicon nitride.Following the tests, SEM was used to elucidate the wear mechanism and particularly to delineate the effects of relative humidity on the wear and friction. SEM micrographs showed that the main wear mechanism at low relative humidity (32%) was caused by mechanical wear including abrasive grooves, large holes and polishing, whereas at high relative humidity (90%) the main mechanism was highly influenced by a tribochemical reaction related to the moisture adsorption from the environment. It is concluded that the removal of lubricious tribolayer was occurred by delamination induced crack propagation. 相似文献
3.
《中国有色金属学会会刊》2021,31(12):3613-3625
Dry sliding wear behaviour of stir-cast aluminium matrix composites (AMCs) containing LM13 alloy as matrix and ceramic particles as reinforcement was investigated. Two different ceramic particle reinforcements were used separately: synthetic ceramic particles (B4C), and natural ceramic particles (ilmenite). Optical micrographs showed uniform dispersion of reinforced particles in the matrix material. Reinforced particles refined the grain size of eutectic silicon and changed its morphology to globular type. B4C reinforced composites (BRCs) showed maximum improvement in hardness of AMCs. Ilmenite reinforced composites (IRCs) showed maximum reduction in coefficient of friction values due to strong matrix−reinforcement interfacial bonding caused by the formation of interfacial compounds. Dry sliding wear behaviour of composites was significantly improved as compared to base alloy. The low density and high hardness of B4C particles resulted in high dislocation density around filler particles in BRCs. On the other hand, the low thermal conductivity of ilmenite particles resulted in early oxidation and formation of a tribo-layer on surface of IRCs. So, both types of reinforcements led to the improvement in wear properties of AMCs, though the mechanisms involved were very different. Thus, the low-cost ilmenite particles can be used as alternative fillers to the high-cost B4C particles for processing of wear resistant composites. 相似文献
4.
5.
The effects of tribochemically induced dissolution of alumina and zirconia ceramics, and the surface-charge modulation within the tribocontact were investigated using a reciprocating sliding test in various chemical environments. For the pH range 1–13, the wear rate in both materials was observed to vary by as much as an order of magnitude, with the highest wear being observed at the isoelectric point of each material. The observed results at extreme pH values can be understood in terms of localized chemical dissolution of each material, assisted by mechanical microcracking, whereas the highest wear rate at around the isoelectric point results mainly from the formation and fracture of the tribochemical layer. 相似文献
6.
Al-Pb alloy was modified by high current pulsed electron beam and the microstructure, hardness and tribological characteristics were characterized by scanning electron microscopy, electronic microanalysis probe microanalysis, Knoop hardness indentation and pin-on-disc type wear testing machine. The results show that the microstructure and hardness can be greatly improved, and the modification layer consists of a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone and a transition zone followed by the substrate. The tribological properties of high current pulsed electron beam irradiated Al-Pb alloy are correspondingly improved largely. Optical observation and scanning electron microscopy analysis reveal that the low wear rate and lowest level in coefficient of friction at high load level for irradiated Al-Pb alloy are due to the formation of a lubricious tribolayer covering the worn surface, which is a mixture of Al2O3, Pb3O4 and silicate. The wear mode varies from oxidative wear at low load to film spalling at high load and, finally, adhesive wear. 相似文献
1