An Investigation On Injection Molding Of Zirconia And Alumina-boron Carbide Ceramics

Compared to the other molding technology, ceramic injection molding technologyhas its unique advantages and characteristics, especially in the field of producing smalland complex ceramic products. In this paper, the effects of binder system, debinding andsintering parameters on the properties of zirconia and alumina-boron carbide ceramicswere studied in order to determine the process conditions.Zirconia and alumina-boron carbide ceramics were shaped by the injection moldingand sintered at different temperature. The section microstructure, TG-DSC curves,volume density, optimum process parameters were determined by scanning electronmicroscope (SEM), TGA-DTA, Archimedes principle, orthogonal experimental analysismethods.Thermoplastic binder system with85wt%zirconia was injection molded whichcontains6.9wt%paraffin wax,7.1wt%polypropylene and1wt%stearic acid. Thedegreasing temperature was investigated by TG-DSC curves and the debinding curvewas established, then the samples were sintered at1550℃，and microstructure of thesintered samples was observed by SEM. Combined with the samples’ density, the bestmolding parameters was confirmed.Alumina-boron carbide ceramics were researched base on zirconia ceramicinjection molding using the same thermoplastic binder system as above. Thedecomposition behaviors of binders and feedstock were analyzed by TG-DSC curves tofind process conditions during which the binder can be completely removed from theproducts without damage. The best parameters for injection were determined by therelative density and surface of the samples which were measured by scanning electronmicroscopy (SEM). Associated with orthogonal experiment the optimal parameters wereas following: the injection pressure is65MPa, injection speed is60m/s and temperaturefor injection is150℃. After all the above steps the samples were sintered at1550℃for 3h under argon protective atmosphere.By controlling the above factors of the binder system, injection, degreasing andsintering parameters, and the ceramics with desired density, accurate dimension anddesired mechanical properties have been made successfully.