High temperature tribological behaviors and wear mechanisms of NiAl–NbC–Ag composites formed by in-situ decomposition of AgNbO3

• Published in: Tribology international Vol. 141; p. 105898
• Main Authors: Feng, Xiaochun, Lu, Cheng, Jia, Junhong, Xue, Jiali, Wang, Qihua, Sun, Yuan, Wang, Wenzhen, Yi, Gewen
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.01.2020; Elsevier BV
• Subjects: Chemical reactions; Coefficient of friction; Crystal structure; Decomposition; High temperature; In-situ decomposition; Intermetallic compounds; Low temperature; Lubrication; Nickel aluminides; Nickel base alloys; Nickel compounds; Niobium carbide; Organic chemistry; Particulate composites; Perovskites; Sintering (powder metallurgy); Tribological behaviors; Tribology; Wear mechanisms; Tribological behaviors; In-situ decomposition; High temperature
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2019.105898

NiAl–NbC–Ag composites were successfully prepared by vacuum-hot-pressing sintering with directly addition of AgNbO3 powders, where AgNbO3 were synthesized using a solid state reaction method. The tribological behaviors of composites were evaluated from 25 °C to 800 °C. The consequences reveal AgNbO3 are completely decomposed during sintering process and in-situ formed NiAl–NbC–Ag composites, which hold excellent high temperature tribologicial properties. At mid-low temperature, NAB20 (NiAl-20 wt%AgNbO3) has a relative lower friction coefficient compared to NiAl, which was attributed to the existence of Ag. While the lowered friction coefficients at 600 °C and 800 °C were attributed to the lubricating glaze layers formed by tribo-chemical reaction on the worn surfaces, which were consisted of typical layered structure Ag2Nb4O11, perovskite AgNbO3 with a highly flexible crystal structure and AgNb3O8. •AgNbO3 are completely decomposed during sintering and in-situ formed NiAl–NbC–Ag.•The micro-hardness of composites is significantly improved with hard NbC formed.•NAB20 registered the lowest COF (0.3) and the wear rate (3.5 × 10−5) at 800 °C.•At mid-low temperature, the improvement of COF was ascribed to soft metallic Ag.•The films formed were made up of Ag2Nb4O11, AgNbO3 and AgNb3O8 at 600 °C and 800 °C.