1988 Fiscal Year Final Research Report Summary
Study on Development of Gas Tunnel Type High Power Plasma Jet
| Project/Area Number |
61850132
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
溶接工学
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| Research Institution | Osaka University |
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Principal Investigator |
KOBAYASHI Akira Osaka University, Welding Research Institute Associate Professor, 溶接工学研究所, 助教授 (70110773)
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| Co-Investigator(Kenkyū-buntansha) |
HIRATA Yoshinori Osaka University, Research Assistant, 工学部, 助手 (00116089)
YOSHIKAWA Takao Osaka University, Professor, 基礎工学部, 教授 (00029498)
OHMURA Etsuji Osaka University, Research Assistant, 溶接工学研究所, 助手 (90144435)
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| Project Period (FY) |
1986 – 1988
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| Keywords | Plasma jet / Gas tunnel / Vortex / High energy density / Plasma spraying / High quality coating / セラミックス |
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| Research Abstract |
The characteristics of gas tunnel type high power plasma jet were experimentally clarified. and the application to a thermal processing (plasma spraying) was carried out. The results of this study can be summarized as follows.
The gas tunnel type plasma jet has a high thermal efficiency. and it is relatively easy to obtain an extremely high power of more than 200 kW.
1. The basic characteristics of a gas tunnel type plasma jet has been investigated. The plasma jet produced in the low-pressure gas tunnel was longer than a conventionally produced jet. and had a positive volt-ampere characteristic. The electrical potential gradinet reached more than 40 v/cm and the energy density was estimated to be more than 10^6W/cm^2. 2. To realize more high power of plasma jet. problems on the structure of the gas tunnel type plasma jet was considered. and the 2mprovement of the torch was carried out.
It is possible to obtain high quality ceramic coatings even at power levels as low as 20kW using this new type of spraying torch. 1. The gas tunnel type plasma spraying apparatus produces coatings with an approximately 30% higher vickers hardness than coatings produced using a conventional plasma spraying apparatus. The vickers hardness of Al_2O_3 coatings. for example. was a value of 1200 at 40kW. Ceramic coatings produced with the gas tunnel type have much smaller pores than coatings produced with a conventional type. 2. The deposit characteristics of Al_2O_3 powder sprayed onto a substrate by this type of plasma spraying were also studied and the relation between the deposit characteristics and the spraying distance was investigated. Estimation of the deposit characteristics was found to be a very effective method for determining the proper spraying conditions under which a good quality coating can be obtained.
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