Kenya Motoyoshi

The Development of Ceramic Injection Molding

The method of forming thin ZrO2 bodies by Injection molding process using acrylic binder was studied. Concerning reological characteristics and properties of thermal decomposition, acrylic binder was compared with the more generally used wax binder. The flowing characteristics of the mixture of acrylic binder indicated high viscosity and gradual change in relation between temperature and viscosity. The compacts using acrylic binder had high flexural strength compared with those using wax binder. As a result, it was observed that ZrO2 mixed with acrylic binder filled the mold without defects. A mechanism for removing acrylic binder from compact which is different from that of wax binder was found. This mechanism made it possible to remove, without defects, acrylic binder, and to control the quantity of gas which decomposes the binder in the inner part of compact. Mixture with 45vol% acrylic binder was the best composition for injection moldability and removing binder. Sintered ZrO2 compact was densified by HIP (Hot Isostatic Pressing), and its mechanical properties were equal to those of the conventional process.