MICROSTRUCTURE AND THERMAL STRESS RELAXATION OF ZrO2-Ni FUNCTIONALLY GRADED MATERIAL
(School of Materials Science and Engineering,Harbin Institute of Technology, Harbin 150001)
Abstract: The microstructural characteristics and thermal stress relaxation of ZrO2-Ni functionally gradient materials (FGM) by hot-pressing were studied. The investigation by scanning and transmission electron microscopy as well as X-ray diffractometry demonstrated that the chemical composition and microstructure of ZrO2-Ni FGM distributed gradiently in stepwise way. The constituents, both zirconia and nickel, were continuous in microstructure everywhere, eliminating the macroscopic interface in traditional ceramics/metal joint. By means of finite element method, the thermal stress distribution in a layered ZrO2/Ni material (nonFGM) and that in a ZrO2-Ni FGM under an analogical condition with great temperature difference were preliminarily analyzed. It was shown that the thermal stress value in ZrO2-Ni FGM remarkably decreased and distributed more smoothly in comparison with that in ZrO2/Ni non-FGM. Obviously the ZrO2-Ni FGM has the function of thermal stress relaxation.
Key words: functionally graded material zirconia nickel microstructure thermal stress relaxation