レーザピーニングを施工した窒化ケイ素セラミックスの機械的特性の評価

抄録

Laser peening (LP) is a surface treatment process that uses a high-energy pulsed laser to generate a compressive residual stress near the surface of the treated material. Although LP has been mainly applied to metals, there are still few cases in which LP has been performed on ceramics. The introduction of compressive residual stress by LP leads to further improvement in the reliability of the ceramics. Herein, LP was conducted on silicon nitride/silicon carbide (Si₃N₄/SiC) composites, and the influence of the LP conditions on the surface properties, such as the residual stress and surface roughness, was investigated. The surface roughness was increased by LP due to the laser ablation effect, and cracks were initiated on the surface due to the use of the pulsed laser if the power density and coverage were too high. A compressive residual stress up to 230 MPa was introduced on the surface by LP without causing surface peeling or chipping. Considering the increase in surface roughness, the occurrence of surface cracks, and the magnitude and depth of the compressive residual stress, optimal LP conditions could be identified.