Study on coated layer material characteristics of coated particle fuel FBR, 3; Thick layer coating process of TiN and gas-nitriding treatment of Ti metal

Naganuma, Masayuki  ; Mizuno, Tomoyasu

Helium gas cooled FBR is one of attractive core concepts, so that the design studies have been performed in the Japanese feasibility study. Here, the coated particle fuelling core is considered to be promising. One of key issues of that fuel is the coated layer material, and TiN is regarded as one of possible materials. Therefore, tests of thick coating of TiN and gaseous nitriding of Ti metal were conducted in this study. In the thick coating tests, PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition) are selected as coating methods. As a result, both methods are found to have capability to form 100 micrometer that is the target of the practical design. Then, as an alternative method to form thick layer, authors contrived the method to nitride Ti metal by nitrogen gas and conducted tests. As a result, the specimen with 100 micrometer thickness was found to be nitrided entirely in 1,200C and 48 hours. However, the nitrided specimen has tendency to be brittle.