Extended Behavior of Crack During Thermal Shock Testing of HVOF Sprayed CoCrW Coatings
Extended Behavior of Crack During Thermal Shock Testing of HVOF Sprayed CoCrW Coatings
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DOI：
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发表时间：
2015
影响因子：
0.6
通讯作者：
Lv Yan-hon
中科院分区：
文献类型：
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作者：
Lv Yan-hon
为了研究CoCrW涂层的抗热冲击性能，利用JP5000 HVOF设备制备了CoCrW涂层，并对800℃高温保温和25℃水淬条件下的裂纹扩展行为进行了分析。结果表明：经过40次热循环后，涂层表面出现了均匀分布的净裂纹和横截面上的垂直裂纹，但涂层上没有分层现象；在基体、涂层和裂纹界面附近存在主要的氧化物al2o3。分析了热应力和相变应力是裂纹扩展和扩展的主要驱动力，但裂纹吸收了热冲击产生的能量，避免了应力集中在涂层内，有利于提高涂层的抗热冲击性能。分散分布的Al2O3降低了涂层与基体之间的结合强度，热冲击的最终破坏模式可能是涂层在界面处的分层。
To study the thermal shock resistance,the CoCrW coatings were prepared by using the JP5000 HVOF equipment,and the extended behavior of cracks during the thermal shock test under 800℃ high temperature holding and water quenching at 25 ℃ was analyzed.The results show that after 40times' thermal cycles there are net cracks evenly distributed around the surface and vertical cracks in the cross section but no delaminating phenomenon on the coating;there exists the main oxide-Al2O3 near the interface of substrate,coating and cracks.Thermal stress and transformation stress are analyzed to be the main driving forces for crack growth and propagation,however,the crack absorbed the energy produced during the thermal shock and avoids the stress concentration in the coating,which can be favor of improving thermal shock resistance of the coating.The discretely distributed Al2O3 decreases the adhesion strength between the coating and the substrate,and the final failure mode of the thermal shock may be the delamination of the coating at the interface.