Pulsed Nd3+:YAG Laser Assisted Micro-dimple Formation in Chromium Films under Different Ambient Conditions

摘要

In this paper, a pulsed laser-assisted micro-dimple formation on chromium film deposited on acast iron piston ring under different ambient conditions, such as deionized water, coaxially flowingAr inert gas (200 kPa), atmospheric air and vacuum (0.003 Pa) is reported. A pulsed nanosecondNd3+: YAG laser with a wavelength of 532 nm, pulsed repetition rate of 10 Hz and with a pulsewidth of 6 ns was used. The key laser variables selected for study is pulse energy (5 - 30 mJ) andnumber of pulses (50,100 pulses). The geometrical features like diameter, depth and aspect ratiowhich are the important attributes that influence the quality of a drilled micro-dimples arecomprehensively investigated. In all the ambient conditions, the diameter and the depth of microdimplesincreased with increase in the laser ablation energy. On the other hand, the diameterincreased and the depth of micro-dimple decreased as the ambient condition changed from vacuum,air, inert gas and water. In the case of water ambience, the overall efficiency of laser ablation waslower than that of other media. Nevertheless, it offered process advantage in terms of less heataffected zone and micro cracks.