| 摘要 |
PURPOSE:To obtain a ceramics tube having biological affinity at excellent dimensional precision with high mass productivity by forming calcium phosphate- based ceramics into a hollow tube shape by ultraplastic forming. CONSTITUTION:The raw material powder of calcium phosphate-based ceramics such as apatite or tertiary calcium phosphate is molded into a tube shape. This tube shape is sintered to obtain a sintered body showing ultraplasticity. The mean grain size of the sintered body is preferably regulated to 10mum or below in order to reveal ultraplasticity. Then ultraplastic forming is performed for this sintered body. Working temp. is 600 deg.C or more and the ultraplastic forming is performed at the temp. of 50 deg.C lower than sintering temp. Generally this working temp. is preferably regulated to 600-1200 deg.C. At this time, 1-70MPa tensile stress is obtained at about 0.01-50mm/min tensile velocity. Deformation rate becomes about 0.1-1.5 in true warp. The tube having the prescribed dimension is obtained by repeating this ultraplastic forming in accordance with necessity. In this case, it is preferable that the final draw ratio is regulated to about 0.1-1.5 in true warp. |
