Improved sealing treatments for thick thermal barrier coatings
Improved sealing treatments for thick thermal barrier coatings
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DOI：
10.1016/s0257-8972(01)01643-7
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发表时间：
2002-03
影响因子：
5.4
通讯作者：
S. Ahmaniemi;P. Vuoristo;T. Mäntylä
中科院分区：
文献类型：
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作者：
S. Ahmaniemi;P. Vuoristo;T. Mäntylä
以柴油机和燃气轮机为研究对象，采用不同的密封方法对氧化锆基8Y_2O_3-ZrO_2、22MgO-ZrO_2和25CeO_2-2.5Y_2O_3-ZrO_2厚膜热障涂层(1000μm)进行了研究。封接工艺的目的是提高多孔厚热障涂层(TTBC)的耐热腐蚀性能和力学性能。用三种不同的方法对涂层表面进行封接：(1)激光上釉；(2)磷酸铝封接处理；(3)在TTBC上爆轰喷涂致密的顶层涂层。用扫描电子显微镜/能谱(SEM/EDS)和光学显微镜分析了密封剂在涂层中的渗透性和涂层的微观结构。用X射线衍射仪、显微硬度和孔隙率测量对涂层进行了表征。表面致密层厚度均为50-400μm，X-射线衍射仪分析表明，磷酸盐封孔处理引起的一些微小的相变和反应产物，以及激光釉层中的一些晶体取向和相变。在所有情况下，密封涂层外层的孔隙率降低，导致显微硬度值增加。
Zirconia-based 8Y2O3–ZrO2, 22MgO–ZrO2and 25CeO2–2.5Y2O3–ZrO2thick thermal barrier coatings (1000 μm) were studied with different sealing methods for diesel engine and gas turbine applications. The aim of the sealing procedure was to improve the hot corrosion-resistance and mechanical properties of porous, thick thermal barrier coatings (TTBC). The surface of the coatings was sealed with three different methods: (1) laser glazing; (2) an aluminium phosphate sealing treatment; and (3) detonation gun spraying of a dense top coating on the TTBC. Sealant penetration into the coating and the coating microstructure were determined by scanning electron microscopy/energy-dispersive spectrometry (SEM/EDS) and optical microscopy. Coatings were characterised by X-ray diffraction (XRD), microhardness and porosity measurements. The thickness of the densified top layers in all cases was 50–400 μm. XRD analysis showed some minor phase changes and reaction products caused by the phosphate-based sealing treatment and some crystal orientation and phase changes in laser-glazed coatings. The porosity of the outer layer of the sealed coating decreased in all cases, which led to increased microhardness values.