Study On Binder Removal Behavior Of Wax-based Binder Of Ceramic Injection Molding

Binder removal is one of most time-consuming and significant process of injection molded zirconia ceramics. Various defects such as distortion, crack, dent etc .will appear if the debinding process isnot well disposed. The debinding time takes up entire process 2/3 all above time of injection moulding, and this process required time increasing by exponential form becomes with product size increasing. The current technology is perfect for the thin part. But for the thick part with large size, the debinding technology remains to be improved and studied.Based on the TGA-DTA curves of injection molded zirconia ceramic, the debinding behavior and feasibility is studied so as to optimize the debinding technology for the thick and large size part. Through the infrared analysis, Peroxides appear accompanied with injection mouldings colors change for 170℃to 300℃.The chemic kinetics analysis shows that temperature increasing rate is the crucial factor which leads to the debinding defects. In low temperature range, Paraffin is the main component in binder removal, the evaporation mechanism is primarily dominant pyrolytic mechanisms.During the liquid phase binder removal process, the swiftest debinding rate is obtained by using the alumina as adsorbent, which particle size is 100 mesh to 200 mesh. Through the research of influence of temperature increasing rate to paraffin wax debinding behavior, the experiment results show that binder removal quality is decrease with the increasing temperature rate increases. Paraffin wax can be removed thoroughly by 8h heat preservation at 210℃. Below 210℃, the logarithm of remained binder quality is linear relationship to the inverse of diameter of mouding.The experimental results also show that no debinding defects injection molded zirconia ceramics which the diameter is 8.2mm are gained when the zirconia powder average particle size is 0.2 to 0.4μm. According to the given debinding schedule the debinding time is greatly reduced and the technology of binder removal is significantly optimized.