Fe-Al／Al2O3梯度涂层制备过程中的热机械行为

在分析涂层中热应力产生机理的基础上,根据等离子喷涂制备过程中的实际受热条件和力学原理,建立了估算制备引起的涂层热应力的计算模型,并依此估算了Fe3Al-Al2O3涂层中的制备应力.通过对涂层微观结构的SEM观察,研究了Fe3Al-Al2O3涂层制备过程中的热机械行为特征及其对涂层性能的影响.结果表明,在梯度涂层中,随着组成成分的变化,热机械性能参量与制备应力均相应变化.最大热应力产生于梯度涂层的底层,从基体到表面沿厚度方向热应力逐渐减小.梯度涂层中的最大应力与平均应力值都小于单一Al2O3涂层中的热应力值.涂层与基体的热失配是涂层中热应力产生的根本原因.涂层成分的梯度化,可有效地缓和制备过程中的热应力.

Thermal-mechanical Properties of Fe3Al/Al2O3 Composite Graded Coatings

On the basis of analyzing the formation mechanism of thermal-stress in coatings, according to practical thermal conditions and mechanical principle, the calculating model that can estimate thermal stress of coatings during fabricating process is established, and this type of stress has been calculated. Through observing the microstructure of coatings by SEM, the thermal mechanical behavior and its effect on the properties of coatings are studied. The results show that, in graded coatings, parameters of thermal mechanical behavior and fabrication stress change with the compositions. The highest stress exists in the bottom layer and the thermal stress decrease from the substrate to the surface. In graded coatings, the highest stress and the average stress are both lower than that in single Al_2O_3 coatings. Thermal discompatibility is the key reason of thermal stress in coatings. The gradient distribution of coatings' composition can effectively reduce thermal stress during fabrication process.