摘要
为降低氧化钇稳定氧化锆(YSZ)热障涂层的表面粗糙度,并获得表面釉化效果以提升其表面性能,采用飞秒激光器脉冲串模式对YSZ热障涂层进行抛光上釉一体化处理。通过研究飞秒激光脉冲串模式下不同子脉冲数对涂层表面形貌、表面粗糙度和釉化层厚度的影响,并评估抛光上釉一体化处理前后的抗热腐蚀性能,获得了较优的飞秒抛光上釉一体化处理工艺参数。结果表明,飞秒激光以脉冲串模式扫描后,涂层粗糙度可降低74%以上,而不同子脉冲数对涂层粗糙度的影响较小。随着子脉冲数的增加,釉化层厚度逐渐减小,而表面裂纹的宽度逐渐增加。当子脉冲数为10时,釉化层孔隙率降至最低6.8%,热腐蚀后涂层表面保持完好,结合区未出现横向裂纹。飞秒激光脉冲串模式利用相对温和的热作用方式和较长的作用时间,通过子脉冲数调整实现涂层气化比例与重熔比例的调控,从而获得了优化的表面粗糙度和抗热腐蚀能力。
Objective Yttriastabilized zirconia(YSZ),as a material for thermal barrier coatings,is widely used for the protection of hightemperature components in gas turbines and aeroengines.YSZ coatings prepared by atmospheric plasma spraying have high surface roughness,loose structures,and many pores and cracks.These factors can lead to the frictional wear of the coating,the susceptibility to molten salt corrosion causing the coating to fail and peel off,and the reduction in lifespan of the coating.Laser polishing can reduce the surface roughness,improve the aerodynamic performance of the components,hinder the penetration of molten salts,and reduce the stress concentration.Laser glazing can improve the loose structure,repair the surface defects,enhance the resistance to thermal corrosion,and thereby extend the service life.This paper proposes an integrated laser polishing and glazing processing technology.The coating is treated using the femtosecond laser pulse train mode for integrated polishing and glazing.Preliminary conclusions on the mechanism of femtosecond laser polishing and glazing are drawn,providing valuable reference for femtosecond laser pulse train mode processing.Methods This paper uses atmospheric plasma spraying technology to prepare YSZ thermal barrier coatings on the substrate.Femtosecond laser technology is utilized for the polishing and glazing integration treatment of the coating.A laser confocal microscopic system is employed to observe and measure the surface roughness and the threedimensional morphology before and after polishing.Scanning electron microscope and metallographic microscope are used to characterize the crosssectional morphology of the coating.An Xray diffractometer is used for phase analysis of the original coating and the coating after experimentation.A mixture of NaCl and Na₂SO₄molten salt powder is first uniformly spread on the coating surface before and after polishing at a deposition amount of 20 mg/cm²,and then heated to 900℃at a rate of 10℃/min and held at temperature for 4 h to test the resistance of the coating to molten salt corrosion.Results and Discussions The surface of the coating forms a flat polished area after undergoing the polishing and glazing integration treatment with a femtosecond laser.In the pulse train mode,the coating surface exhibits vaporization and a“melting peak filling valley”effect(Fig.3).The change in the number of subpulses has little impact on the surface roughness of the coating.The coating roughness can be reduced by more than 74%after femtosecond laser scanning in pulse train mode(Fig.4).As the number of subpulses increases,the width of cracks on the coating surface gradually increases.After the polishing and glazing integration treatment,a dense glazed layer forms on the surface of the coating.In the pulse train mode,as the number of subpulses increases,the thickness of the glazed layer gradually decreases,but this leads to an increase in crack width.When the number of subpulses is 10,the porosity of the glazed layer is reduced to the minimum of 6.8%(Fig.6).The main phase component of the coating before and after the polishing and glazing integration treatment is the nonequilibrium tetragonal phase of zirconia(t′-ZrO2),and the polishing and glazing integration treatment does not lead to the formation of harmful monoclinic phase zirconia(mZrO2)(Fig.8).After thermal corrosion,the original coating develops distinct horizontal cracks between the thermal barrier coating and the bond coat.In contrast,the coating that has undergone the integrated polishing and glazing treatment maintains its surface integrity after thermal corrosion,the internal structure of the coating is largely preserved,and no horizontal cracks are observed(Fig.9).Conclusions The femtosecond laser polishing and glazing integration process can significantly reduce the surface roughness of YSZ coatings,reducing the original roughness Sa of 7.5μm to below 2.0μm.Using the pulse train mode can effectively improve the surface morphology and the quality of the glaze layer,with the porosity of the glaze layer being as low as 6.8%.Compared to the original coating,the coating after the polishing and glazing integration treatment exhibits superior resistance to thermal corrosion.Under the process with 10 subpulses,the coating adheres well,and no significant transverse cracks are observed.The femtosecond laser pulse train mode optimizes the proportion of material vaporization and remelting under a laser action through a more gentle heating method and a longer duration of action.By adjusting the number of subpulses,precise control over the morphology and thickness of the glaze layer can be achieved.
作者
王梁
韩宜
王亚星
于真鹤
张盼盼
吴国龙
陈智君
姚建华
Wang Liang;Han Yi;Wang Yaxing;Yu Zhenhe;Zhang Panpan;Wu Guolong;Chen Zhijun;Yao Jianhua(Institute of Advanced Laser Manufacturing,Zhejiang University of Technology,Hangzhou 310023,Zhejiang,China;College of Mechanical Engineering,Zhejiang University of Technology,Hangzhou 310023,Zhejiang,China;AECC Shenyang Liming AeroEngine Co.,Ltd.,Shenyang 110043,Liaoning,China)
出处
《中国激光》
北大核心
2025年第12期131-141,共11页
Chinese Journal of Lasers
基金
国家重点研发计划(2022YFB4601500)
国家自然科学基金(52035014)
“尖兵领雁+X”研发攻关计划(2024C01178)。
关键词
YSZ涂层
飞秒激光
脉冲串模式
抛光上釉一体化
YSZ coating
femtosecond laser
pulse train mode
integration of polishing and glazing
