Unmelted particles in plasma sprayed coatings
Unmelted particles in plasma sprayed coatings
复制标题
等离子喷涂涂层中未熔化的颗粒
DOI：
10.1016/s0955-2219(03)00104-3
复制
发表时间：
2003
影响因子：
5.7
通讯作者：
A. Tricoire
中科院分区：
文献类型：
--
作者：
P. Ctibor;Olivier Roussel;A. Tricoire
介绍了一种研究等离子喷涂中未熔化颗粒和涂层孔隙率的技术。对未熔化粒子进行了研究。这项技术是基于大面积截面(LAS)图像，叠加以获得密集排列的“列”图像，作为特定体积的等离子喷涂涂层的3D地图。使用了涂层抛光横截面的光学显微照片。LAS技术结合了两个参数--放大倍率和视场大小。这样的组合通常超出了光学显微镜的范围。该方法需要一次又一次地对样品进行抛光，在每个抛光步骤之后，新的LAS与先前的LAS精确地对齐。未熔化的颗粒被认为在等离子喷涂过程中已经在等离子体羽流中球化，但在到达基材之前已经冷却到熔点以下。这种颗粒如先前固化的那样嵌入在涂层中，即具有球状形状。3-D图使得观察它们在涂层内的分布成为可能。这些球形颗粒代表沉积涂层中的缺陷。此外，在应力或其他物理因素的影响下，它们有各向同性的倾向，并且以这种方式在涂层的各向异性结构中作为二次缺陷的中心，恶化了涂层的功能性能。
A technique is described for investigation of unmelted particles in plasma spraying and for porosity investigation in coatings. A study of unmelted particles is made. The technique is based on large area section (LAS) images, superimposed to obtain a densely packed “column” of images as a 3-D map of a certain volume of the plasma sprayed coating. Optical micrographs of a polished cross section of the coating were used. The LAS technique combines two parameters—magnification and field size. Such a combination is normally beyond the range of optical microscopy. The method makes it necessary to polish the sample again and again and after each polishing step align precisely the new LAS with the previous one. The unmelted particles are considered to have been spheroidized in the plasma plume during plasma spraying, but to have cooled below the melting point before reaching the substrate. Such particles are embedded in the coating as previously solidified, i.e. with globular shape. The 3-D map makes it possible to observe their distribution inside the coating. These globular particles represent defects in the deposited coating. Moreover they have a tendency to behave isotropically under the influence of stress or other physical factors and in this way serve in the anisotropic structure of the coating as centers of secondary defects deteriorating the functional properties of the coatings.