共查询到18条相似文献,搜索用时 62 毫秒
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采用有限元分析软件ANSYS对1Cr13Ni9Ti、Ni、45钢和2Cr13基体等离子喷涂Sm2Zr2O7/YSZ热障双层涂层系统的残余热应力分布进行了数值仿真.结果表明:复合涂层系统表面层及界面存在较大的径向残余热应力,且径向、轴向及剪切应力梯度随金属基体的热膨胀系数增加而增大;涂层系统的轴向应力及剪切应力在径向距离距中心处约2/3的范围内基本不变,呈现出与基体材质的无关性. 相似文献
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采用实验和数值方法研究了陶瓷层厚度比对La2Ce2O7/YSZ(LC/YSZ)热障涂层热震性能的影响。实验结果表明,随着LC与YSZ厚度比的降低,涂层热震寿命显著提高,涂层失效区域逐渐向试样中心转移,剥离位置逐渐从两陶瓷层界面附近转移到LC内靠近上表面处。数值结果表明,界面边缘处较大的轴向应力与剪切应力易导致较大厚度比涂层边缘处剥落;LC表面中心区域较大的径向拉应力会导致垂直裂纹萌生,并伴随界面偏折,这是较小厚度比涂层自LC内部剥离的原因。 相似文献
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大气等离子喷涂ZrO2与Sm2Zr2O7热障涂层的残余热应力分析 总被引:1,自引:0,他引:1
采用ANSYS软件计算了等离子喷涂Sm2Zr2O7和ZrO2涂层的残余热应力,并与涂层部分性能实验结果进行了对比.结果表明:在两涂层表面存在较大的径向残余热应力,该应力随径向距离的增加而增大,并在试样边沿处急剧下降.在表面陶瓷层与金属粘结层界面处存在较大的径向拉应力和剪切压应力,二者同样随径向距离增加而减小,并在试样边沿处急剧下降,而轴向应力在边沿处急剧递增.Sm2Zr2O7,涂层的残余应力大于ZrO2涂层,较大表面径向应力使得Sm2Zr2O7涂层表面存在较为宽大的显微裂纹,界面处较大的残余应力使得Sm2Zr2O7涂层结合强度下降,计算结果与实验吻合良好. 相似文献
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目的 研究退火过程中La Mg Al11O19热障涂层内部残余热应力的分布情况及其对热障涂层热稳定性的影响机理。方法 基于等离子喷涂制备的La Mg Al11O19/YSZ双热障涂层物理模型,采用Abaqus建立数值仿真模型,通过温度位移耦合计算,系统分析不同退火温度下LaMgAl11O19热障涂层内部残余热应力的分布情况。通过扫描电镜,观察退火前后涂层表面及断面的微观组织形貌。根据数值模拟结果及涂层SEM图像,分析残余热应力对LaMgAl11O19热障涂层热稳定性的影响,探究引起涂层裂纹损伤失效的影响因素。结果 数值模拟结果显示,La Mg Al11O19热障涂层内部的残余热应力以径向应力为主,其值远大于轴向应力及剪切应力。退火中,径向残余热应力在径向距离0~2.4mm内缓慢增长到最大值,而在x=2.4mm至径向边缘范围内急剧降低。退火后,在涂层径向边缘位置出现应力集... 相似文献
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稀土锆酸盐与8YSZ所组成的双陶瓷层涂层是目前热障涂层领域研究的热点,而陶瓷层厚度对其热冲击性能有着显著影响。采用有限元软件ANSYS研究了表层厚度对Sm2Zr2O7/8YSZ热障涂层淬冲击热应力的影响,并与单一Sm2Zr2O7涂层进行了比较。结果表明,在Sm2Zr2O7/8YSZ涂层的表面处具有最大的径向热冲击应力,最大轴向应力则存在于陶瓷层/金属粘结层界面处,涂层各处剪应力基本相当。涂层表面及两陶瓷层界面处的径向热应力随表层厚度的增加而减小,陶瓷层/粘结层界面处径向应力则随表层厚度增加而增大。每个界面处的轴向应力随表层厚度增加而降低,而剪应力绝对值则随表层厚度增加而增大。与单一Sm2Zr2O7涂层相比,Sm2Zr2O7/8YSZ涂层的热应力明显偏小,说明增加涂层的层数有利益改善涂层的抗热冲击性能。 相似文献
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界面粗糙度对热障涂层残余应力和裂纹演化的影响 总被引:1,自引:0,他引:1
由于残余应力的作用是造成热障涂层失效剥落的主要因素之一,本工作采用不同幅值的正弦曲线来模拟粗糙度对陶瓷层(TBC)-结合层(BC)界面处残余应力分布的影响;以内聚力模型模拟TBC-BC界面,研究了在外加机械载荷作用下粗糙度对界面裂纹萌生和扩展的影响。结果表明,粗糙度对残余应力分布以及裂纹的形核与扩展有很大的影响。随着粗糙度的增大,陶瓷层和结合层靠近界面的波峰波谷处最大拉/压应力也增大。当施加一定拉伸位移载荷时,最大损伤与裂纹首先在幅值最小的波峰波谷处产生。 相似文献
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用HVOF(CoNiCrAlY)+SFPB+APS(8YSZ)制备热障涂层,经1000℃高温氧化2,26,310h后,用EDS和拉曼荧光光谱对涂层进行分析。高温氧化2h,首先生成的是γ-Al2O3,此后,γ-Al2O3向α-Al2O3转化。拉曼荧光光谱检测和理论计算表明,高温氧化过程中,TGO中的微观热生长残余应力先增加后降低,310h高温氧化后微观热生长残余应力比26h高温氧化后的低0.476GPa。SFPB技术使粘结层表层区域产生扩散通道,高温氧化的瞬态阶段,大量比Al3+半径大的其它离子通过此扩散通道,抑制了γ→θ→α的相变。最终形成了以α-Al2O3为主相的TGO抗高温氧化层。 相似文献
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Al/Ni-ZrO2 gradient thermal barrier coatings are made on aluminum substrate using plasma spraying method and one direction thermal shock properties of the coatings are studied in this paper. The results show that pores in coatings link to form cracks vertical to coating surface. They go through the whole ZrO2 coating once vertical cracks form. When thermal shock cycles increase, horizontal cracks that result in coatings failure forms in the coatings and interface. And vertical cracks delay appearance of horizontal cracks and enhance thermal shock property of coatings. Failure mechanisms of coating thermal shock are discussed using experiments and finite element method. 相似文献
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Plasma sprayed ZrO2 ceramic coating has been widely used in many industrial fields due to its simple manufacturing process, low cost, and good heat insulation effect. However, the structure and service conditions of thermal barrier coatings are complex, and residual stresses will inevitably occur during the preparation process as well as application. Residual stress has the most obvious influence on the life of thermal barrier coatings, seriously reducing the bonding strength between the coating and the substrate, and ultimately showing the cracking and spalling of the coating, greatly reducing the service time and stability of the coating during service. To realize the prediction and detection of the residual stress, it is necessary to seek a reliable detection method for thermal barrier coating to effectively predict the accumulated residual stress in the cooling process of coating and reduce the influence of residual stress on the stability of the coating. In this paper, the finite element model of plasma-sprayed ZrO2 coating was established by using the birth and death element method. Gauss heat source was used to simulate the heat source condition of plasma spraying, and the residual stress and its distribution of the coating cooling to room temperature were studied. The residual stress of ZrO2 coating prepared by plasma spraying was detected by X-ray diffraction and Raman spectroscopy to explore the accurate detection method of residual stress in ceramic coating. Through the analysis of the finite element results, it is found that the number of elements is reasonable and the calculation time is short when the mesh unit size of the model is 1.75 mm. The maximum temperature of the coating temperature field obtained by simulation is consistent with the test temperature in the experiment, and the simulation results are accurate. It can be concluded that the residual stresses in the central region of the plasma spraying coating after cooling to room temperature are larger than those in the edge region, which are mainly concentrated in the central region of heat flow. There is large stress at the bonding interface of each layer, which causes the stress to change significantly along the thickness direction of the coating. The equivalent stress of the coating is 160-220 MPa. The X-ray method was used to detect the residual stress of plasma sprayed coating. To obtain an isolated, complete, high peak position and high peak intensity with enough diffraction peaks to avoid the influence of texture, (331) crystal plane with a high multiplicity factor was selected as the characteristic peak. The test results show that the residual stress in the coating will make the position of the characteristic diffraction peak shift to a high angle at 2θ=153°. The residual stresses of 180-185 MPa were detected by X-ray diffraction. The I6 peak in the Raman spectrum of the coating was used as the characteristic peak of the spectrum to represent the frequency shift of the Raman spectrum band. Compared with the original spraying powder, the position of the Raman characteristic peak of the ceramic coating shifted to the low-frequency direction, indicating that there was residual tensile stress after the coating was cooled. The Raman-stress factor of the ZrO2 coating was calibrated to be 8.33 (cm·GPa)-1, and the residual stress of the coating was calculated to be 174-180 MPa. In this paper, the finite element method can effectively simulate the residual stress inside the coating when the plasma spraying reaches room temperature. It has good matching with the XRD and Raman spectrum detection results. There is about 180 MPa residual stress inside the coating when the coating is cooled to room temperature, seriously affecting the stability of the coating. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved. 相似文献