Improvement of reliability of ceramics by laser peening and crack-healing

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04231
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Materials/Mechanics of materials
• Research Institution: Yokohama National University
• Principal Investigator: TAKAHASHI Koji 横浜国立大学, 大学院工学研究院, 教授 (90334630)
• Research Collaborator: SAIGASA Kazuya ; SHIBUYA Norihito
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: レーザピーニング / 残留応力 / セラミックス / 曲げ強度

Outline of Final Research Achievements

The aim of this study is to improve the strength and reliability of ceramics by laser peening. We applied laser peening to silicon nitride and investigated its properties such as the surface roughness, bending strength, residual stress, hardness, and fracture toughness. Based on the evaluation results, the optimum laser peening conditions were selected. Compressive residual stress was induced by laser peening up to a depth of 60 μm. By the effect of the compressive residual stress introduced by laser peening, the bending strength of silicon nitride was improved, and the scatter of the bending strength was reduced. Thus, laser peening is effective to improve the strength and reliability of ceramics.

Free Research Field

材料強度学

Academic Significance and Societal Importance of the Research Achievements

セラミックスは耐熱性，耐摩耗性に優れているために，高温エネルギー機器等の高温構造材料への適用が期待されている．しかし，セラミックスは破壊靭性値が低いために，加工時や使用中にき裂が発生した場合には，強度と信頼性が大幅に低下する可能性がある．本研究では，セラミックスにレーザピーニングを施工することにより，曲げ強度と信頼性を向上できることを新たに見出した．難切削材のセラミック工具や，人工関節用のセラミック部材，高温エネルギー機器等，種々のセラミックス部材に対してレーザピーニングを適用することにより，強度および信頼性を向上できると考えられる．