The nanoindentation and erosion of sapphire

• Main Authors: Ji-Kua Tai, 戴嘉况
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/32959617481092804025

碩士 === 義守大學 === 機械與自動化工程學系碩士班 === 98 === This study investigated the mechanical properties and cavitation erosion of the sapphire single crystal with Kyropoulos method. The raw material with 75wt% of chunk accompanied 25wt% of powder was heated up to 2100℃, and cooled off gradually at a velocity of 15mV/hr. The nanoindentation load-displacement behavior of sapphire tested with a Berkovich indentor for hardness and elastic modulus. An ultrasonic facility operating at 20 KHz was used to erode the material. The results indicated the hardness and elastic modulus are among 260-210 GPa and 30-20 GPa, respectively. The creep stress exponents for both m-plane and a-plane were found to exhibit a relative low value (0.5). It was shown that the incubation period without visible weight losses in the sample could be more than ten hours. The experiments were also performed using a gas-blast erosion rig with SiC and Al2O3 erodents. The results suggest that the larger erodent particles are more effective in displacing and damaging the surface compared to the smaller particles, and lead to higher wear rate