Thermal Error Compensation of the Wear-Depth Real-Time Detecting of Self-Lubricating Spherical Plain Bearings

The spherical plain bearing test bench is a necessary detecting equipment in the research process of self?lubricating spherical plain bearings. The varying environmental temperatures cause the thermal deformation of the wear?depth detecting system of bearing test benches and then a ect the accuracy of the wear?depth detecting data. However, few researches about the spherical plain bearing test benches can be found with the implementation of the detect?ing error compensation. Based on the self?made modular spherical plain bearing test bench, two main causes of ther?mal errors, the friction heat of bearings and the environmental temperature variation, are analysed. The thermal errors caused by the friction heat of bearings are calculated, and the thermal deformation of the wear?depth detecting sys?tem caused by the varying environmental temperatures is detected. In view of the above results, the environmental temperature variation is the main cause of the two error factors. When the environmental temperatures rise is 10.3 °C, the thermal deformation is approximately 0.01 mm. In addition, the comprehensive compensating model of the thermal error of the wear?depth detecting system is built by multiple linear regression(MLR) and time series analysis. Compared with the detecting data of the thermal errors, the comprehensive compensating model has higher fitting precision, and the maximum residual is only 1 μm. A comprehensive compensating model of the thermal error of the wear?depth detecting system is proposed, which provides a theoretical basis for the improvement of the real?time wear?depth detecting precision of the spherical plain bearing test bench.

DEVELOPMENT OF MoS_2-CONTAINING Ni-Cr BASED ALLOYS AND THEIR HIGH-TEMPERATURE TRIBOLOGICAL PROPERTIES

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Tribological behavior and microstructural evolution of lubricating film of silver matrix self-lubricating nanocomposite

The aim of this study is to fabricate the nanocomposite with low friction and high wear resistance using binary solid lubricant particles.The microstructure and tribological performance of the nanocomposite are evaluated,and the composition and film thickness of the lubricating film are observed and analyzed by scanning electron microscopy(SEM)and X‐ray photoelectron spectroscopy(XPS).The nanocomposite exhibited improved tribological properties with a friction coefficient as low as 0.12 and a low wear rate of 2.17×10^(-6) mm^(3)/(N∙m)in high‐purity nitrogen atmosphere.Decreasing sliding speed can increase lubricating film thickness,and the thickest lubricating film is approximately 125 nm.As the film thickness of the lubricating film exceeded 90 nm,the friction coefficient curves became smooth.In compared with WS_(2),MoS_(2) can be more effective in forming the transfer layer on the worn surfaces at the initial stage of the tribological process.

Self-lubrication of tribologically-induced oxidation during dry reciprocating sliding of aged Ti–Ni51.5 at% alloy

The tribological behaviors of Ti–Ni51.5 at%alloy strengthened by finely dispersed Ni_(4)Ti_(3) particles in reciprocating sliding against GCr15,Al_(2)O_(3),and ZrO_(2) at room temperature were studied.Interestingly,the coefficient of friction(COF)suffered a sheer drop(from 0.9 to 0.2)when the aged alloy slid against GCr15 at a frequency of 20 Hz under a 20 N load without lubrication.However,severe‐mild wear transition disappeared when a solutionized alloy was used.Moreover,the COF stabilized at a relatively high level when Al_(2)O_(3) and ZrO_(2) were used as counterparts,although their wear mechanisms showed signs of oxidation.Scanning electron microscopy(SEM)and X‐ray element mappings of the wear scars of the counterparts clearly indicate that the formation of well‐distributed tribo‐layer and material transfer between the ball and disk are pivotal to the severe‐to‐mild wear transition in the aged Ti–Ni51.5 at%alloy/GCr15 friction pair.The higher microhardness and superelasticity of the aged alloy significantly accelerate the material transfer from GCr15 to the disk,forming a glazed protective tribo‐layer containing Fe‐rich oxides.

Dry Sliding Wear Behavior of Silver Containing Ni-Based Composite-Steel Tribo-Pair

Ni-based self lubricating composites containing four different amounts of silver were prepared by powder metallurgy(PM) route.The room temperature friction and wear behavior was investigated by carrying out dry sliding experiments against bearing steel using a ring-on-disk configuration.Tests were conducted at a constant load of 100 N and different sliding speeds of 0.5,1.0 and 1.5 m/s to analyze the effect of both the speed and the silver content on the wear behavior of the tribo-pair.The friction coefficient and the wear rate of the composites were found to decrease with increasing both the sliding speed and the silver content.The wear rate of the counterface was observed to be a little higher when it was siding against the composite having silver in comparison to that without any silver.However,the overall wear rate of the tribo-pair was found to decrease with increasing sliding speed and silver content.