Journal of Thermal Spray Technology ( IF 3.1 ) Pub Date : 2022-05-10 , DOI: 10.1007/s11666-022-01412-1 Tina Ghara , P. P. Bandyopadhyay
A comparative study on the mechanical properties and residual stress profiles of ceramic coatings produced using plasma spraying under comparable conditions are presented. Alumina, titania, alumina-13%titania, zirconia and chromia coatings were deposited, for the first time, under similar particle velocity and a comparable particle temperature to melting temperature ratio. The coatings were characterized by porosity, hardness, indentation modulus, and fracture toughness, and full residual stress depth profiles of the coated specimens. The degree of particle melting and associated coating properties relied on the latent heat of fusion of the feedstock. The top coatings were found to possess different residual stress field depending on their coefficient of thermal expansion. The effect of tensile quenching stress is perceived when the difference in thermal expansion coefficients between the topcoats and the bond coat is low, e.g., titania and zirconia coatings. On the other hand, for a higher differential thermal expansion coefficient, effect of compressive thermal stress is prevalent, e.g., alumina, alumina-titania, and chromia coatings. Moreover, the highly compressive residual stress in the grit blasted substrate was relaxed after coating deposition, and the extent of stress relaxation was dependent on plasma power. Hence, the full residual stress state in a coated component relied on the combined influence of the difference in thermal expansion coefficients between the topcoat and bond coat, degree of feedstock melting, and the extent of stress relaxation owing to annealing effect by the plasma jet.
中文翻译:
在相当的粒子温度和速度下沉积的等离子喷涂陶瓷涂层的机械性能和残余应力深度分布
介绍了在可比条件下使用等离子喷涂生产的陶瓷涂层的机械性能和残余应力分布的比较研究。氧化铝、二氧化钛、氧化铝-13%二氧化钛、氧化锆和氧化铬涂层首次在相似的粒子速度和相当的粒子温度与熔化温度比下沉积。涂层的特征是孔隙率、硬度、压痕模量和断裂韧性,以及涂层试样的完整残余应力深度分布。颗粒熔化的程度和相关的涂层性能取决于原料的熔化潜热。发现顶部涂层根据它们的热膨胀系数具有不同的残余应力场。当面涂层和粘合涂层(例如二氧化钛和氧化锆涂层)之间的热膨胀系数差异较低时,会感觉到拉伸淬火应力的影响。另一方面,对于较高的微分热膨胀系数,压缩热应力的影响是普遍的,例如氧化铝、氧化铝-二氧化钛和氧化铬涂层。此外,喷砂基体中的高压缩残余应力在涂层沉积后得到了松弛,应力松弛的程度取决于等离子体功率。因此,涂层部件中的全部残余应力状态取决于面涂层和粘合涂层之间的热膨胀系数差异、原料熔化程度和等离子射流退火效应引起的应力松弛程度的综合影响。