2002 Fiscal Year Final Research Report Summary
Prevention of Laser Welding Defect in Cobalt-Chromium Alloy for Dental Use
| Project/Area Number |
13672068
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
補綴理工系歯学
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| Research Institution | Osaka Dental University |
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Principal Investigator |
KAKIMOTO Kazutoshi Osaka Dental University, Department of Dentistry, Assistant, 歯学部, 助手 (20194681)
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| Co-Investigator(Kenkyū-buntansha) |
INOUE Taro Osaka Dental University, Department of Dentistry, Assistant, 歯学部, 助手 (50309184)
KOMASA Yutaka Osaka Dental University, Department of Dentistry, Professor, 歯学部, 教授 (10131385)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Laser Welding / Cobalt-Chromium alloy / Weld Defect |
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| Research Abstract |
We elucidated the cause of weld defects in cobalt-chromium alloy by pulsed Nd: YAG laser such as the crack and the porosity. We investigated alloy composition, which did not cause crack, and welding methods of preventing generation of weld defects.
The following results were obtained.
There were no crack in weld of the alloy, which was composed of only cobalt, chromium and molybdenum. Therefore the cause of the crack was thought to be silicon and carbon.
The crack generated easily so that there ware composition elements of investment into the cast.
The casting cobalt-chromium alloy for dental use melted from the grain boundary. In the alloy, which generated easily the crack, it began to melt from small spots of the grain boundary. The densities of silicon, oxygen and phosphorus were high melted beginning part. In the alloy, which generated cracks easily, the melt began from the entire grain boundary and melted boundary with the matrix was not clear.
In Nd: YAG laser welding with the rectangular pulse wave, if thickness was 1.7 mm or less for pure titanium, the welding without porosity was possible. But, it was very difficult to obtain a deep penetration weld without porosity at the cobalt-chromium alloy.
We examined the prevention of porosity generated in the laser weld of the casting cobalt-chromium alloy for dental use by the wave control. But it was difficult to prevent porosity generation completely. In addition, it will be necessary to investigate it in the future. In pure titanium, porosity generation was prevented by wave control though it was not complete.
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