Diboride Zirconium Target Material And The Thin Film Preparation Technology Research

ZrB2thin films coating on UO2fuel elements are used as Integral-Fuel-Burnable-Absorbers in nuclear reactor. In this paper, ZrB2ceramics were prepared by ordinary sintering, hot-pressing(HP) and spark plasma sintering(SPS) using ZrB2powder as raw material respectively. ZrB2target prepared by isostatic pressing molding and ordinary sintering was used to prepare thin films by magnetron sputtering, and thin films deposited on Si and UO2substrates were synthesized. The microstructures of ZrB2ceramics and films were observed by scanning electron microscope (SEM). The phase·constituents and compositions of ZrB2ceramics and films were analyzed by X-ray diffraction (XRD), X-ray energy dispersion spectroscope (EDS) and X-ray photoelectron spectroscopy(XPS). The densities of samples were measured by Archimedes drainage method. The modulus and hardness of films were measured by nanoindentation. This paper has focused its efforts on the bonding quality through several methods, such as thermal shock, stretching and nano scratch tester. Some results were as follows.ZrB2powder could be sintered by all of the three sintering methods. Hot-pressing is an effect method for getting high density sintered product. Sintered body made by original powder has a relative density of84.7%. Product produced by powder with additive has a91.5%relative density. And sintered body made by milled powder get a relative density of99.1%. Product sintered by milled powder with additive has the highest density, it reached99.4%of its theory density and almost be full density. The relative density of SPS and ordinary sintering product are76.7%and71.0%.The big sintered body made by ordinary sintering can be processed into target which is tolerable for synthesizing films through magnetron sputtering. Two kind of films with similar features and compositions were gotten under the same technological parameter even the two kind of targets were low density and high density respectively.The modulus and hardness of films deposited on Si are340GPa and40GPa measured by nanoindentor.ZrB2films were bonded well with substrates. ZrB2films could bear a thermal cycle from80℃to600℃for five times. And the critical load of film is about450mN.The results show that films deposited on Si and UO2substrates were compact, uniform and well bonded with the substrates. It is feasible to prepare ZrB2films on the surfaces of UO2fuel elements by magnetron sputtering.