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 si tu. The results indicate that the parts expanded dramatically as soon as th ey came into contact with preheated water. After the initial sharp expansio n, moulded compacts swelled slowly and reached the maximum expansion. The d imensions of specimen then maintained at a fixed value and the parts finall y shrank drastically when water was drained out. Based on the results obtai ned, the causes of length changes for specimens immersed in water are discu ssed. In addition, the effects of debinding temperature and molecular weigh t of PEG on the length changes of specimens were also examined. (C) 2000 El sevier Science Ltd. All rights reserved.