J Mater Sci Technol ›› 2009, Vol. 25 ›› Issue (02): 264-268.

• Articles • Previous Articles     Next Articles

Influence of the Compacts Homogeneity on the Incidence of Cracks during Thermal Debinding in Ceramic Injection Molding

Xianfeng Yang, Zhipeng Xie and Yong Huang   

  1. State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
  • Received:2008-03-26 Revised:2008-07-22 Online:2009-03-28 Published:2009-10-10
  • Contact: Zhipeng Xie
  • Supported by:

    the National Nature Science Foundation of China (NSFC) under grant No. 50572049
    the National High Technology Research and Development Program of China (“863 Program”) under grant No. 2007AA03Z522.

Abstract:

During thermal debinding in ceramic injection molding, the inhomogeneity of green body is a key origin of cracks. In this study, the impact of low molecular weight binders on the homogeneity of the green body was investigated. Incidence of cracks during thermal debinding indicated that the volume ratio of wax to stearic acid should be out of high viscosity and incompletely wetting region. In these two formulation regions, typical inhomogeneous microstructures were observed. By mercury intrusion method, it was shown that pore size distribution of the debinded compacts was determined by thermal degradation of low molecular weight binders. A particle-rich region model was established to predict the nucleation of cracks caused by solid loading fluctuation. The criterion of cracks nucleation was that local capillary force from solid loading fluctuation was larger than the suction force from the surroundings.

Key words: Ceramic injection molding, Cracks, Debinding, Homogeneity