Cold Spraying: A New Alternative Preparation Method for Nickel-Based High-Temperature Solid-Lubrication Coating

Cold spraying was first used for the purpose of preparing nickel-based high-temperature lubrication coatings. High-quality In625-Cr2O3-Ag composite coatings were deposited by a high-pressure cold-spray system, and their tribological properties were evaluated at 20 and 1000 degrees C by a high-temperature tribometer. The microstructure, composition, and wear mechanisms of the coatings were analyzed by x-ray diffraction, scanning electron microscopy, and Raman spectroscopy. The measurements showed that the cold-sprayed In625-Cr2O3-Ag composite coatings have a very dense structure, good bonding strength to substrate, low friction coefficient, and excellent wear resistance. The friction coefficients of the In625-Cr2O3-Ag coatings were around 0.3 and the wear rates of the coating were maintained at about 10(-5) mm(3)/N m at 20 and 1000 degrees C. The experimental observation of the wear tracks revealed that the silver provided lubrication at 20 degrees C. As the temperature increased up to 1000 degrees C, a lubrication layer with low shear strength made up of Ag(2)MoO(4)and Cr(2)O(3)was formed on the wear track