Constrained sintering of an air-plasma-sprayed thermal barrier coating
Constrained sintering of an air-plasma-sprayed thermal barrier coating
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DOI：
10.1016/j.actamat.2010.04.015
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发表时间：
2010-07-01
期刊：
影响因子：
9.4
通讯作者：
Fleck, N. A.
中科院分区：
文献类型：
--
作者：
Cocks, A. C. F.;Fleck, N. A.
建立了高温合金厚基体上空气等离子喷涂热障涂层约束烧结的细观力学模型。涂层包括随机的飞溅物，其间有硬币形裂纹。裂纹面在粗糙处接触，粗糙通过界面扩散在使用中逐渐烧结，并通过体积蠕变调节。扩散是由发展中的接触和局部粗糙接触应力的界面能的减少所驱动的。在升高的操作温度下，烧结和蠕变应变都在涂层平面内积累。研究了烧结速率和显微组织演化速率对动力学参数和热力学驱动力的敏感性。它表明，烧结响应是由三个独立的时间尺度，由涂层的材料和几何性质所决定。最后，通过比较约束烧结与自由烧结的速率来评估衬底约束的作用。(C)2010 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
A micromechanical model is presented for the constrained sintering of an air-plasma-sprayed, thermal barrier coating upon a thick superalloy substrate. The coating comprises random splats with intervening penny-shaped cracks. The crack faces make contact at asperities, which progressively sinter in-service by interfacial diffusion, accommodated by bulk creep. Diffusion is driven by the reduction in interfacial energy at the developing contacts and by the local asperity contact stress. At elevated operating temperature, both sintering and creep strains accumulate within the plane of the coating. The sensitivities of sintering rate and microstructure evolution rate to the kinetic parameters and thermodynamic driving forces are explored. It is demonstrated that the sintering response is governed by three independent timescales, as dictated by the material and geometric properties of the coating. Finally, the role of substrate constraint is assessed by comparing the rate of constrained sintering with that for free sintering. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.