Preparation Of Al-based Ceramic Composite Coatings By The Method Of Mechanical Alloying

During the process of the mechanical alloying, due to the repeated collisions the powderundergoes cold welding and fragment, a collection of powders tend to adhere to the surface of ballsand the inner wall of chamber, for which a coating layer of certain thickness forms. Based on the“pollution”, Al-ZrO₂-Y₂O₃、Al-Al₂O₃and Al-Al₂O₃-ZrO₂-Y₂O₃powders were used to prepare theAl-based ceramic composite coatings using five different milling-parameter in this paper.The Al-ZrO₂-Y₂O₃coating was firstly deposited on the surface of SUS304. The results showedthat the micro-hardness of the surface, the friction-wearness and the the high-temperature oxidationresistance of the coating were well proved.The Al-Al₂O₃composite coating was obtained by MA with the same milling parameters, it wasfound that its microstructure was fully improved, that the thichness of coatings turned larger andcracks became less. We also found that the coatings of largest thickness up to0.6mm were obtainedwhen the rotate speed was400r/min after8hours’ milling, of which the micro-hardness was thelargest and the friction coefficient was the smallest, also the coatings’ high-temperature oxidationresistance got better contrasting with Al-ZrO₂-Y₂O₃coating syetem.The Al-Al₂O₃-ZrO₂-Y₂O₃composite coating was obtained by MA under the same millingcondition. Though the thickness of Al-Al₂O₃-ZrO₂-Y₂O₃composite coating was smaller than theAl-Al₂O₃coating, author found that the consistence and the homogenization were well enhanced. Theproperties that micro-hardness, friction wearness and the high-temperature oxidation resistance gotthe best when setting a bowl rotation speed of400r/min and a milling time of8h.Based all of the results, the author also studied the fabrication principle of Al-based ceramiccomposite coatings by mechanical alloying and the mechanism of the high-temperature oxidationresistance that Al has influence on the Al-based ceramic composite coatings.