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

摘要

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 degrees C to 800 degrees 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 degrees C and 800 degrees 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.