Experimental study on the tribo-chemical smoothening process between self-mated silicon carbide in a water-lubricated surface-contact reciprocating test

Abstract

Silicon carbide (SiC) can be tribo-chemically smoothened during a self-mated sliding procedure in the aqueous environment. As well reported in the point-contact tests, this smoothening process works well due to the abundant water as oxidant. After this smoothening process, the tribo-surface is well polished, a closely mated tribo-gap naturally forms, and an ultra-low friction state is built. However, water in the tribo-gap could be insufficient in industrial applications, e.g., the seal gap in mechanical seals. In this study, the tribo-chemical smoothening behavior in such environment was researched. A surface-contact reciprocating test was used to simulate the aqueous environment where water was insufficient. After tests, compared to the published results from the point-contact tests, the same ultra-low friction state was achieved. A part of the tribo-surface was tribo-chemically smoothened. The obtained smoothened surface microstructure was consistent with the published information. Meanwhile, severe abrasive wear occurred. A porous oxygen-rich layer was found existing beneath the abrasion-induced grooves, in which numerous smashed wear debris adhered on the worn surfaces. We concluded that the shortage of water initiated the severe abrasion, meanwhile the generated wear debris aggravated the wear condition. This understanding is instructive for developing new methods to avoid the severe abrasion in the same water insufficient environment.

Ultrastable Lubricating Properties of Robust Self-Repairing Tribofilms Enabled by in Situ-Assembled Polydopamine Nanoparticles

“…In Figure a, it can be found that water plays a decisive role in lubrication of the PDA tribofilm. Interestingly, Si 3 N 4 would also react with water, resulting in a colloidal silica layer as a good lubricant, as shown in reactions and . , However, water in the Si 3 N 4 /metal interface could be insufficient under boundary lubrication, which is difficult to form a stable colloidal silica layer . Meanwhile, in PDA-aq, the PDA tribofilm is hydrophilic and can strongly form a stable “solid-like” water film on the interface .…”

“…The diameter of the wear scar is close to 200 μm, and the surface is quite rough. The results imply that the Si 3 N 4 ball is seriously worn and cannot exert self-lubricating properties because of insufficient water on the friction interfaces under boundary lubrication . In contrast, the wear scar on the steel disc in GO-aq becomes smaller and shallower (Figure d) because the adsorption of GO on the contact interface is beneficial for wear reduction.…”

“…Table S2 shows the detection of SiO 2 by XPS. Severe wear causes oxidation of Si 3 N 4 on the surface of the ball against Al 2 O 3 . The ball against steel is only slightly worn in Figure a, which is supposed to have a lower Si–O component.…”

Study on the Mechanism of Solid-Phase Oxidant Action in Tribochemical Mechanical Polishing of SiC Single Crystal Substrate

“…The flash point temperature during polishing excites the oxidation reaction in Equations ( 18)- (20). Therefore, the temperature of the test environment is so low that it does not affect the occurrence of thetribochemical reaction and has little effect on friction behavior [48,49].…”

Comprehensive review of tribometer dynamics-Cycle-based data analysis and visualization

“…Tribometer dynamics can be identified in sensor data using appropriate filtering techniques and can be segregated effectively from signal noise. In particular, in cases where only long-time transient behavior is considered, e.g., when only one average value of the coefficient of friction (CoF) is reported per stroke or cycle [17,19,20], a meticulous analysis of time-resolved sensor data may increase the significance of the reported experimental results [21,22].…”