1992 Fiscal Year Final Research Report Summary
Study on Formation of the Composite Coatings by Thermal Spraying
| Project/Area Number |
02555154
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属材料(含表面処理・腐食防食)
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| Research Institution | Kurume National College of Technology |
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Principal Investigator |
ITO Hiroshi Kurume National College of Tech., Mat. Science and Met. Eng., Professor, 材料工学科, 教授 (10151531)
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| Co-Investigator(Kenkyū-buntansha) |
SHIROYAMA Masaharu Nippon Tungsten Co., Ltd., Second Research and Development Division, Section Chi, 第二研究開発部, 主幹
NAKAMURA Ryozo Kurume National College of Tech., Mat. Science and Met. Eng., Assistant, 材料工学科, 助手 (70044279)
UMAKOSHI Mikio Kurume National College of Tech., Mat. Science and Met. Eng., Associate Professo, 材料工学科, 助教授 (10091357)
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| Project Period (FY) |
1990 – 1992
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| Keywords | Composite Coating / Wire Explosion Spraying / Plasma Spraying / WC-Co Coating / HIP / Mechanofusion Process / Wear Test |
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| Research Abstract |
Study on formation of the composite coatings by thermal spraying was done for the purpose of improving the wear resistance of metals. The mild steel substrates were coated with various materials by the wire explosion and plasma spraying methods, and the properties of coatings such as wear resistance, adhesion strength, hardness, etc. were investigated.
1. Wire Explosion Spraying (1) The Mo and WC-Co coatings were formed with various discharge energy densities. The parameters such as porosity, etc. were correlated with adhesion strength between the coating a nd substrate. (2) Regarding the WC-Co coatings, it was clarified that the Co content in the coatings was lowered and WC was decarburized to W_<1-x>C, W_2C with increasing in the discharge energy density. (3) The Ni-P alloy was infiltrated into the WC-Co coatings, and then wear resistance of its coating was much improved. (4) The WC-6.5%Co-Mo composite coating had the most excellent wear resistance at the Mo content of 25 vol% when the WC-6.5%Co and Mo wires were exploded and sprayed alternately on the substrate.
2. Plasma Spraying (1) The sprayed Al_2O_3 coating was covered with PTFE. The rolling wear test indicated that the PTFE-Al_2O_3 composite coating wore much less than the Al_2O_3 coating. (2) The s prayed WC-Co coating was post-treated with HIP at lower temperature and pressure than ordinary HIP treatment. Wear resistance of the HIP-treated coating was about three times as well as the as-sprayed coating. (3) Ni-Al composite powders were prepared by the mechanofusion process and were sprayed in air or a vacuum. The properties of these powders and coatings were almost the same as those of commercial ones. (4) The WC-12%Co coating was deposited with the aero-plasma s praying torch "Twin Anode alpha". The coating sprayed with the agglomerated powder under optimum conditions showed to have about twice wear resistance compared with the conventional air-plasma sprayed coating.
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