Creation of high-strength biomaterial by hybrid surface treatment using functionally graded layer

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K17986
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Materials/Mechanics of materials
• Research Institution: National Institute of Technology, Toyota College
• Principal Investigator: Nakamura Yuki 豊田工業高等専門学校, 機械工学科, 准教授 (10612939)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 超高サイクル疲労 / ハイドロキシアパタイト / チタン合金 / 傾斜機能層 / 微粒子ショットピーニング / プラズマ溶射

Outline of Final Research Achievements

Fine particle peening (FPP) using hydroxyapatite (HAp) particles was applied to titanium alloys to form the hydroxyapatite transferred and functionally graded layer on the surface. As a result, HAp transferred layer and functionally graded layer were formed on the specimen surface by FPP. In the FPPed specimen, Vickers hardness was increased by FPP compared with that of the untreated specimens, resulting in work-hardening. Rotary bending fatigue tests were carried out on FPPed, plasma sprayed, FPP + plasma sprayed and untreated specimens. The FPPed specimens exhibited higher fatigue strength than the untreated specimens. It is due to the increase in hardness and compressive residual stress by FPP. On the other hand, significant deteriorations of the fatigue strength for the plasma sprayed specimen was observed in comparison with the result for the untreated specimen. The fatigue strength of FPP + plasma sprayed specimen exhibited almost the same fatigue strength as untreated specimen.

Free Research Field

材料強度学

Academic Significance and Societal Importance of the Research Achievements

溶射材の疲労強度改善には溶射皮膜のはく離および基材と溶射皮膜の界面強度を制御することが重要である．本研究では，これまで製品加工の最終処理として用いられてきたショットピーニングを，その特性を積極的に利用して溶射の前処理として施すことで学術的課題の解決を試みた．その結果，溶射後の疲労強度も未処理材と同程度確保できることが明らかとなり，将来本研究で得られた知見を利用することで産業分野において使用されている溶射材の安全性・信頼性向上，ひいては溶射処理の革新的なプロセスの確立に寄与するものと期待される．