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Most studies of liquid lubricants were carried out at temperatures below 200 °C. However, the service temperature of lubricants for aerospace and aeroengine has reached above 300 °C. In order to investigate the friction mechanism and provide data for high temperature lubrication, the friction and wear properties of chlorophenyl silicone oil (CPSO)-lubricated M50 steel and Si3N4 friction pairs were investigated herein. Ball-on-disk experimental results show that the lubrication performance of CPSO varies significantly with temperature. Below 150 °C, coefficient of friction (COF) remains at 0.13–0.15 after the short running-in stage (600 s), while the COF in the running-in stage is 0.2–0.3. At 200 °C and above, the running-in time is much longer (1,200 s), and the initial instantaneous maximum COF can reach 0.5. Under this condition, the COF gradually decreases and finally stabilizes at around 0.16–0.17 afterwards. This phenomenon is mainly due to the different thickness of boundary adsorption film. More importantly, the wear rate of M50 steel increases significantly with the temperature, while the wear rate barely changes at temperatures above 200 °C. The anti-wear mechanism is explained as tribochemical reactions are more likely to occur between CPSO and steel surface with the increased temperature, generating the FeCl2 protective film on the metal surface. Accordingly, FeCl2 tribochemical film improves the lubrication and anti-wear capacity of the system. At high temperatures (200–350 °C), FeCl2 film becomes thicker, and the contact region pressure becomes lower due to the larger wear scar size, so the wear rate growth of M50 steel is much smaller compared with that of low temperatures (22–150 °C). The main findings in this study demonstrate that CPSO lubricant has good anti-wear and lubrication capacity, which is capable of working under temperatures up to 350 °C. [ABSTRACT FROM AUTHOR]

With the development of technical requirements, the current challenges faced by bearing materials mainly revolve around high-temperature conditions and the trend towards material lightweighting. Full ceramic bearings are the new candidate due to their excellent properties. This article details the tribological and adsorption performance of chlorophenyl silicone oil (CPSO) as a high-temperature lubricant in ceramic tribological systems (ZrO2, Al2O3, and Si3N4). Among the three ceramic tribological systems, the lubrication performance can be ordered as Si3N4 > Al2O3 > ZrO2, as the wear rates of the ZrO2 and Al2O3 tribo-systems are almost 1135.67 and 283.33 times larger than that of the Si3N4 tribo-system, respectively. The observed results can be explained by the superior adsorption performance of CPSO on a Si3N4 ceramic surface, which was calculated by molecular dynamic simulation. The molecular dynamic simulation results show the adsorption energy of CPSO/Si3N4 is almost 54.09 and 61.18 times higher compared to that on ZrO2 and Al2O3 ceramics. These findings provide experimental and theoretical insights for understanding the lubrication performance of CPSO in a full ceramic tribo-system. [ABSTRACT FROM AUTHOR]

As pivotal structural component, steels operating at high temperatures play a vital role in promoting the development of advanced equipment technology. Enduring and efficient lubricants are critical bottleneck for the construction of high-temperature frictional subsystems. Polydiethylsiloxane oil (PDES) significantly reduces the coefficient of friction (COF) (9.80–16.74 %) and wear rate (28.95–54.59 %) in the Si3N4–8Cr4Mo4V system without sulfur and phosphorus anti-wear additives at 250 °C. With only 1 wt% PDES, there is a remarkable 28.95 % wear rate reduction in the Si3N4–8Cr4Mo4V frictional system. The enhanced lubrication performance come from the Si–O tribofilm at lower PDES concentrations (1–15 wt%). Once exceeding a PDES concentration of 30 wt%, the as-formed Si–O tribofilm transitions to a Fe–Mo compound film, exhibiting superior friction reduction and wear resistance properties.

With the development of technical requirements, the current challenges faced by bearing materials mainly revolve around high-temperature conditions and the trend towards material lightweighting. Full ceramic bearings are the new candidate due to their excellent properties. This article details the tribological and adsorption performance of chlorophenyl silicone oil (CPSO) as a high-temperature lubricant in ceramic tribological systems (ZrO2, Al2O3, and Si3N4). Among the three ceramic tribological systems, the lubrication performance can be ordered as Si3N4 > Al2O3 > ZrO2, as the wear rates of the ZrO2 and Al2O3 tribo-systems are almost 1135.67 and 283.33 times larger than that of the Si3N4 tribo-system, respectively. The observed results can be explained by the superior adsorption performance of CPSO on a Si3N4 ceramic surface, which was calculated by molecular dynamic simulation. The molecular dynamic simulation results show the adsorption energy of CPSO/Si3N4 is almost 54.09 and 61.18 times higher compared to that on ZrO2 and Al2O3 ceramics. These findings provide experimental and theoretical insights for understanding the lubrication performance of CPSO in a full ceramic tribo-system.