In situ evaluation of dimensional variations during water extraction from alumina injection-moulded parts

The dimensional variations of alumina injection-moulded compacts containing polyethylene glycol (PEG) binders during solvent debinding were studied. A dilatometer was set up for monitoring the length changes of compacts in situ. The results indicate that the parts expanded dramatically as soon as they came into contact with preheated water. After the initial sharp expansion, moulded compacts swelled slowly and reached the maximum expansion. The dimensions of specimen then maintained at a fixed value and the parts finally shrank drastically when water was drained out. Based on the results obtained, the causes of length changes for specimens immersed in water are discussed. In addition, the effects of debinding temperature and molecular weight of PEG on the length changes of specimens were also examined.