Deformation Mechanisms in Compression‐Loaded, Stand‐Alone Plasma‐Sprayed Alumina Coatings
Deformation Mechanisms in Compression‐Loaded, Stand‐Alone Plasma‐Sprayed Alumina Coatings
复制标题
压缩负载独立等离子喷涂氧化铝涂层的变形机制
DOI：
10.1111/j.1151-2916.2000.tb01682.x
复制
发表时间：
2000
影响因子：
3.9
通讯作者：
K. Faber
中科院分区：
文献类型：
--
作者：
R. Trice;D. Prine;K. Faber
圆柱形，独立管的等离子喷涂氧化铝进行了测试，在压缩在轴向方向在室温下，使用应变计监测轴向和周向应变。使用的主要压缩载荷曲线为循环载荷，峰值应力单调增加。在卸载时的应力-应变响应中观察到滞后，开始于50 MPa的峰值应力。弹性模量随最大外加应力的增加而减小。应力-应变响应仅在低应力下是线性的;在高应力下的非线性程度与施加的应力成比例。在室温下恒定应力下停留一小时显示出时间依赖性的应变响应。使用透射电子显微镜和声发射来研究变形机制，应力-应变响应与裂纹弹出，增长和逮捕。提出了等离子喷涂涂层中的许多缺陷，包括孔隙和微裂纹，作为裂纹成核和/或扩展的网站。当这些小的成核裂纹在外加应力作用下扩展时，它们几乎平行于加载方向沿着层间边界扩展。随着应力的增加，这些裂缝最终连接起来，导致灾难性的破坏。
Cylindrical, stand-alone tubes of plasma-sprayed alumina were tested in compression in the axial direction at room temperature, using strain gauges to monitor axial and circumferential strains. The primary compression-loading profile used was cyclic loading, with monotonically increased peak stresses. Hysteresis was observed in the stress-strain response on unloading, beginning at a peak stress of 50 MPa. The modulus decreased as the maximum applied stress increased. The stress-strain response was only linear at low stresses; the degree of nonlinearity at high stresses scaled with the stress applied. One-hour dwells at constant stress at room temperature revealed a time-dependent strain response. Using transmission electron microscopy and acoustic emission to investigate deformation mechanisms, the stress-strain response was correlated with crack pop in, growth, and arrest. It is proposed that the numerous defects in plasma-sprayed coatings, including porosity and microcracks, serve as sites for crack nucleation and/or propagation. As these small, nucleated cracks extend under the applied stress, they propagate nearly parallel to the loading direction along interlamellae boundaries. With increasing stress, these cracks ultimately link, resulting in catastrophic failure.