High Temperature Tribological Properties of NiCrWAl_2O_3-SrCO_3-Ag Cement Composites
SHAN Yu;LIU Feng;WANG Jian-yi;WANG Wen-zhen;JIA Jun-hong;State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences;School of Materials Science and Engineering, Xian Shiyou University;Graduate University of Chinese Academy of Sciences;
Ni Cr W-Ti_3SiC_2-SrCO_3-Ag composites with different contents of SrCO_3 and Ag were fabricated by powder metallurgical method(mechanical alloying and vacuum hot-pressing sintering). The friction and wear properties were tested by UMT-3 from room temperature to 1 000 ℃. The microstructures, phase compositions and wear mechanism of the composites were analyzed by scanning electron microscopy, energy dispersive spectrocopy and X-ray diffraction.The results show that the decomposition of SrCO_3 and the formation of Sr Al_4O_7 during the hot-pressing. Meanwhile, the new phases such as Cr_2O_3 and NiCr_2O_4 were found. The composite with addition of 10% SrCO_3 and 10% Ag exhibited the best friction and wear properties in a wide temperature range and that was attributed to the formation of the tribolayers containing oxides(SrCrO_4 and Ni O) by tribo-chemical reactions during the medium-high temperature process.Together with Ag and NiCr_2O_4 in composites, SrCrO_4 and NiO worked synergistically to improve the tribological properties of the composites in a wide range of temperatures(400~1 000 ℃).