Preparation of functionally graded mullite-zirconia composite using electrophoretic deposition (EPD)

摘要

The mechanical properties such as hardness and especially fracture toughness of present structural ceramics are not enough to permit design of high performance products. It is generally believed that further improvement of fracture toughness and hardness is only possible by making composites of ceramics with ceramic fiber. The wide-spread use of mullite-zirconia (MZ) composites is due to the fact that the zirconia dispersion in the mullite matrix improves the thermo-mechanical properties. The preparation process to produce the composite sample using electrophoretic deposition (EPD) which deals with three types of powder: α-alumina, silica and zirconia, mixed with the suspension based on 2-butanone, n-butylamine and polyvinyl butyral (PVB). Hardness and fracture toughness were measured using indentation methods on cross sections of the sample with applying two loads: 5kg and 10kg. Electron microscopy analysis (SEM) and X-ray diffraction (XRD) tests were used to examine the microstructure, composition and crystallization behavior of the deposits. The results were compared with mullite matrix properties to detect the enhancement in mechanical properties.