Advanced Ceramic Coatings and Materials for Extreme Environments III
Advanced Ceramic Coatings and Materials for Extreme Environments III
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适用于极端环境的先进陶瓷涂层和材料 III
DOI：
10.1002/9781118807651.ch12
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Chu P
中科院分区：
文献类型：
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作者：
Chu P
本研究的目的是提供一个彻底的检查组成和微观结构的不均匀性在多孔氧化物陶瓷表面层上形成的钛等离子体电解氧化（PEO）。用0.02 ~ 0.05 μ g/L的聚氧化乙烯（PEO）制备了厚度达5 μ m的PEO-TiO_2复合膜。0.04 M NaH 2 PU 4电解质溶液在450. 500伏直流电。采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和场发射透射电子显微镜（FE-TEM）等先进手段对涂层的表面形貌和整个涂层厚度的晶体结构进行了观察。XRD分析表明，表面层由均匀分布在层厚上的金红石和金红石组成。详细的TEM研究表明，在PEO涂层的顶部存在连续的无定形层，该层主要包含Td 3 O2，并从电解质中掺入一些磷。在纳米晶下，存在具有均匀分布的纳米级孔（<50 nm）、纳米金红石（<100 nm）和亚微米级（0.1至lum）金红石微晶的多孔结晶层。大微米尺寸的孔（约1... 3um直径）被纳米晶线包围，发现存在于多孔晶体层的底部，邻近薄的界面阻挡层。讨论了涂层材料的热物理性能、散热条件和涂层形成过程中表面层组织演变之间的相关性。
This study aims at providing a thorough examination of compositional and microstructural heterogeneities in the porous oxide ceramic surface layers formed on Ti by plasma electrolytic oxidation (PEO). The PEO-titania layers of up to 5um thick were produced using 0.02... 0.04 M NaH2PU4 electrolyte solutions in the voltage range of 450... 500 V DC. Advanced methods of X-ray diffractometry (XRD), scanning electron microscopy (SEM) and field-emission transmission electron microscopy (FE-TEM) were employed to observe the surface layer morphology and characterise its crystal structure across the whole coating thickness. As revealed by XRD analysis, the surface layers consist of both anatase and rutile evenly distributed across the layer thickness. Detailed TEM studies showed that a continuous amorphous layer exists at the top of the PEO coating, the layer comprises mainly TÍO2, with some phosphorus incorporated from the electrolyte. Underneath, there is a porous crystalline layer with uniformly distributed nano-scale pores (< 50nm), anatase nanocrystallites (< 100nm) and submicrometer-scale (0.1 to lum) rutile crystallites. Large micrometre size pores (about 1... 3um in diameter) surrounded by nanocrystall ine anatase are found to exist at the bottom of the porous crystalline layer, adjacent to the thin interfacial barrier layer. Correlations between thermal-physical properties of the coating material, heat dissipation conditions and microstructural evolution in the surface layer during coating formation are discussed.