Tribo-Oxidation and Tribological Behavior of TaC-20%SiC Composites at Elevated Temperatures

Tribo-oxidation mechanism and tribological behavior of TaC-20 vol%SiC composites from 25 to 800 & DEG;C coupled with aluminum oxide (Al2O3) and cemented carbide (WC-Co) were investigated. Tribo-oxidation products on the worn surface were analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that as temperature increased from 25 & DEG;C to 800 & DEG;C, the specific wear-rates (WRs) of the composites decreased from 10(-3) mm(3)N(-1)m(-1) to 10(-4) mm(3)N(-1)m(-1) when coupled with Al2O3, while the WRs increased from 10(-6) mm(3)N(-1)m(-1) to 10(-3) mm(3)N(-1)m(-1) continuously when coupled with WC-Co. At 25 & DEG;C, TaC in the composite was partially oxidized into TaO2 as coupled with the two dualities. At 400 & DEG;C, the TaC in composite was oxidized into Ta2O5, while SiC was oxidized into SiCOx as coupled with Al2O3, while they were oxidized into Ta2O5 and SiO2-x as coupled with WC-Co. At 800 & DEG;C, the composites were oxidized into Ta2O5, SiCOx, and SiO2-x as coupled with the two dualities. The segregation of Ta compounds on the surface was promoted by friction. For the composites-Al2O3 tribo-pair, the wear mechanism changed from abrasion and adhesion at low temperature, to abrasion, adhesion, and tribochemical reaction (oxidation) at medium temperature, and adhesion and tribochemical reaction at high temperature. For composites-WC-Co tribo-pair, the wear mechanism was adhesion and tribochemical reaction in the whole temperature range.