Research On Technology Of Preparation Lining Ceramic Layer Using Pre-Permeating Technique

In order to resolve such two problems both bonding strength is low in the interface between metallic matrix and Zirconium oxide coating, and the coating can be flaked easily. Technology of lining ceramics with pre-permeating method by using in this paper, adding pore-former in the powder of green body, preparing micro-porous in the surface of green body through pre-sintering, daubing the surface of green body by using ceramic composite powder slurry, ceramic particles has been infiltrated in the hole of green body before sintering, natural composition of gradient layer is formed. So it is combines strongly and high interfacial bonding strength between lining ceramic layer and green body after sintering, thus overcome spalling in use between lining ceramic layer and green body because of larger difference in coefficient of thermal expansion. The method of adding Fe-Al alloy as transition layer was studied in this paper.Adding pore former in the powder of Iron and Nickel as raw material of green body, Ceramic composite powder slurry which Nickel and 5Y-ZrO₂ nanometer is the main components is made by mixing material applied to the surface of green body, then prepared composite which have lining ceramic layer through sintering process. Sintering used two modes which is vacuum and pumped argon to protect.Result shows that through comparing two pore former which is starch and sawdust, it is found that starch was beneficial to pre-permeating lining ceramics, and optimum adding quantity of starch which is 10% was determined. Analyze the microstructure by using SEM. It is found that through comparing the composition of ceramic composite powder, among them which it with high content of Nickel and with low content of ZrO₂, interface of lining ceramic layer combined fully dense; Conversely, the interface combined loosely, and appeared a little micro-crack; Result shows that lining ceramic layer which composition is P2(Nickel76%+ZrO₂20%), according to process W2(1020℃×60min, argon protection) is the best. Comparison on depth of lining ceramic layer, compactness, distribution uniformity of samples which were sintering in argon protection and vacuum, it is found that the former is better than the latter; Comparison on tissue of lining ceramic layer in different sintering temperature, it is found that tissue is loose in lower temperature, reasons for metal powder is difficult to fully diffusing, therefore, ceramic particles could not be coating closely; Metal powder can be ensued fully diffusion in the sintering temperature of 1050℃, ceramic particles could be coating most closely. Lining ceramic layer prepared by transition layer which is Fe-Al alloy, sintering process parameter has important influence on the interface of lining ceramic layer, lining ceramic layer combines strongly with the green body in the best sintering temperature range(1050℃～1075℃); But holding time can be proper adjustment, if sintering temperature is close to upper limit, and moderate shorten holding time, and vice versa; But if sintering temperature is too high, it will lead to clearly crack between lining ceramic layer and green body, its cause may be different thermal expansion coefficient between ceramic particles and metal.