Study On Injection Molding And Debinding Process Of Sialon Ceramic

Ceramic injection molding is a competitive manufacturing technology for producing geometrically complex parts. The processes including mixing, molding, debinding and sintering are dependent upon the types of binder used. In this paper, the injection molding process of Sialon ceramic which include preparation of the binders, rheology of feedstock, injection molding, binder removal and sintered technology etc. was studied to find out the key factor and obtain defect-free ceramic samples in the end.The rheological characteristic of feedstock is a key factor influencing the properties of molded bodies in ceramic injection molding. The feedstock was made with Si₃N₄ and AlN powder as a raw material and the polymer wax binder consisted of Paraffin Wax(PW), High Density Polyethylene (HDPE), stearic acid(SA) and Dibutyl-o-phthalate(DBP). By using capillary rheometer, rheological parameters of the feedstock were determined. The non-newton index and viscous flow activation energy were calculated by means of linear regression analysis, their rheological behavior was analyzed, The one which has better rheological properties was selected as the final injection molding feedstock.Injection molding process is one of the key steps in the whole experiment, Injection experiment was repeated at injection molding machine of HMD88M3. The green body of different shapes was obtained by different injection parameters, such as injection pressure and injection temperature. The impact of injection molding parameters on green body was inspected, so as to optimized the parameters of the entire process. Meanwhile, defect occurred during the injection molding process was studied, the causes were analyzed and the optimization process was discussed in order to avoid the defects in the method of formation.The next step, solvent debinding was done in waterbath equipment. Effects of debinding temperature, debinding time, different concentrations on binder removal, sample thickness, solvent adding mothod and defferent bulk surface area to volume ratios were investigated. And the maximal binder removal of dissoluble component were studied elementarily. The thermal decomposition behaviors of binders and feedstock are also studied to find process conditions during which the binder can be completely removed from the products without danage or dimensional change. The pressless sintering and crystallization heat treatment process had been studied. The density, hardness and shrinkage rate of the samples were measured after heat treatment.