In order to investigate the thermal shock and the heat conduction property of a target under multi-pulsed laser radiation, analytic expressions of both temperature and thermal stress fields in the target are deduced o...In order to investigate the thermal shock and the heat conduction property of a target under multi-pulsed laser radiation, analytic expressions of both temperature and thermal stress fields in the target are deduced on the basis of the non-Fourier conduction law and the thermo-elastic theory. Taking a stainless steel target as an example, we can solve the analytic expressions under appropriate boundary conditions by using the finite difference method and MATLAB software, and then reveal the evolution law of both surplus temperaturt, and thermal stress in the target. The results indicate that the temperature curves in the target irradiated by a multi-pulsed laser take on a delayed character in different sections away from the boundary, which is only affected by its relaxation time. The front of the stress wave is very steep in the non-Fourier numerical solutions, which presents an obvious thermal shock, so it is necessary to consider the non-Fourier effect of semi-infinite body under the high energy laser radiation.展开更多
The surface morphological changes produced by Nd:YAG pulsed laser ablation of metal Al and semiconductor Si were carefully examined and analyzed by using scanning electron microscope. The formation mechanism of the dr...The surface morphological changes produced by Nd:YAG pulsed laser ablation of metal Al and semiconductor Si were carefully examined and analyzed by using scanning electron microscope. The formation mechanism of the droplets was discussed, and the reasons for formation of the microcracks on the laser irradiated area of the target surface were analyzed by calculating the thermal stress, the vapor pressure and the shock pressure induced by the laser supported detonation.展开更多
为了提高轧辊表面涂层的抗热冲击性能、延长其高温条件下的使用寿命,采用5k W CO2激光器,对轧辊表面等离子喷涂热障涂层进行了重熔处理。利用扫描电镜和能量色散谱仪,观察激光重熔涂层的涂层形貌和微观结构,对分界面元素进行了微区成分...为了提高轧辊表面涂层的抗热冲击性能、延长其高温条件下的使用寿命,采用5k W CO2激光器,对轧辊表面等离子喷涂热障涂层进行了重熔处理。利用扫描电镜和能量色散谱仪,观察激光重熔涂层的涂层形貌和微观结构,对分界面元素进行了微区成分分析。将试样在1000℃下保温10min后,放入常温(25℃)水中激冷,探究其抗热冲击性能,并与等离子喷涂涂层进行了对比。结果表明,经激光重熔后,涂层孔隙、裂纹明显减少,涂层质量明显提高;涂层与基体之间在一定程度上实现了冶金结合,结合强度明显提高;开始出现裂纹以及最终失效时的冲击循环次数由原来的14次和32次分别提高到43次和94次。该激光重熔工艺有助于提高涂层的热冲击性能,可延长轧辊的使用寿命。展开更多
基金supported by the Chinese Natural Science Fund (No.10572020)
文摘In order to investigate the thermal shock and the heat conduction property of a target under multi-pulsed laser radiation, analytic expressions of both temperature and thermal stress fields in the target are deduced on the basis of the non-Fourier conduction law and the thermo-elastic theory. Taking a stainless steel target as an example, we can solve the analytic expressions under appropriate boundary conditions by using the finite difference method and MATLAB software, and then reveal the evolution law of both surplus temperaturt, and thermal stress in the target. The results indicate that the temperature curves in the target irradiated by a multi-pulsed laser take on a delayed character in different sections away from the boundary, which is only affected by its relaxation time. The front of the stress wave is very steep in the non-Fourier numerical solutions, which presents an obvious thermal shock, so it is necessary to consider the non-Fourier effect of semi-infinite body under the high energy laser radiation.
文摘The surface morphological changes produced by Nd:YAG pulsed laser ablation of metal Al and semiconductor Si were carefully examined and analyzed by using scanning electron microscope. The formation mechanism of the droplets was discussed, and the reasons for formation of the microcracks on the laser irradiated area of the target surface were analyzed by calculating the thermal stress, the vapor pressure and the shock pressure induced by the laser supported detonation.
文摘为了提高轧辊表面涂层的抗热冲击性能、延长其高温条件下的使用寿命,采用5k W CO2激光器,对轧辊表面等离子喷涂热障涂层进行了重熔处理。利用扫描电镜和能量色散谱仪,观察激光重熔涂层的涂层形貌和微观结构,对分界面元素进行了微区成分分析。将试样在1000℃下保温10min后,放入常温(25℃)水中激冷,探究其抗热冲击性能,并与等离子喷涂涂层进行了对比。结果表明,经激光重熔后,涂层孔隙、裂纹明显减少,涂层质量明显提高;涂层与基体之间在一定程度上实现了冶金结合,结合强度明显提高;开始出现裂纹以及最终失效时的冲击循环次数由原来的14次和32次分别提高到43次和94次。该激光重熔工艺有助于提高涂层的热冲击性能,可延长轧辊的使用寿命。
