Abstract: Chromic oxide is a kind of ceramic coating materials used in the gas turbine engines for the purpose of anti-wear. The ultrafine YPSZ and WC/Co feedstocks have already been wildly used to prepare the ultrafine structured YPSZ and WC/Co coatings, and the coatings express the better properties comparing to the conventional coatings. Ultrafine chromic oxide powders, prepared by the method of solution precipitation, can not be directly used as plasma spray feedstocks, because of its low mass of individual ultrafine particle and not good flow-ability. In this paper, spray drying and heat treatment are used to reprocess the ultrafine chromic oxide powder. The chromic oxide coating is prepared by plasma spraying. X-ray diffraction (XRD) is used to analyze the phase constituent of the feedstocks and coatings. Scanning electron microscopy (SEM) is used to observe the morphology and particle size of ultrafine powder feedstocks as well as to examine the microstructure of the chromic oxide coating. In addition, free holding density and flow-ability of the feedstocks and hardness and bonding strength of the ultrafine chromic oxide coating are measured. Experimental results show that the large agglomerated ultrafine chromic oxide feedstocks after being reprocessed are spherical, have good flow-ability and high apparent density�Cwhich are suitable for plasma spraying. The properties and microsturcture of the ultrafine chromic oxide coating are perfect comparing to the conventional chromic oxide wear resistance coatings.

Keywords: Ultrafine chromic oxide, Spray drying, Feedstocks, Plasma spraying, Wear resistance coatings