|Budget Amount *help
¥12,100,000 (Direct Cost : ¥12,100,000)
Fiscal Year 1998 : ¥3,600,000 (Direct Cost : ¥3,600,000)
Fiscal Year 1997 : ¥8,500,000 (Direct Cost : ¥8,500,000)
Sintering property depends on ceramics material and additives. Appropriate combination of different kinds of ceramics or those with different amount of additives may cause residual stress in a sintered part and it makes the part tough. In this research, sintering rate and strain rate in sintering process are examined in various sintering conditions. Furthermore, distorsion property of a green molded part in dewaxing process is also examined, because considerable amount of distorsion is found to occur, especially in the region of high shear rate in injection molding process.
Results are summarized as follows :
(1) It was found that residual strain, corresponding to the elongation or shrinkage of polymer molecules, is generated in a molded part. It causes large deformation, when the part is heated in dewaxing process.
(2) Sintering rate, or density rate, depends. on the amount of sintering additives, say MgO in the case of alumina material. Difference of sintering rates corresponding to the difference of sintering additives becomes large at the temperature of 1,400。C-l, 500。C.Sintering rate saturates at 1,600。C.
(3) Relationship between strain-rate and stress in sintering stage is examined from measurement of self weight defection of a simply supported beam, and it was expressed by a simple expression.
(4) A three pillar specimen, in which each pillar contains different amount of additives, is made by two stage injection molding. After dewaxing and sintering, residual stress in each pillar is examined by strain gages. Finally, it was found that tensile residual stress is observed in a pillar with large amount of sintering additives and in other pillars with small amount of additives compression stress is observed, It suggests that it is possible to make compression residual stress in surface of a part by applying appropriate distribution of sintering additives.