硅化钽/硅化钼基热防护涂层短时高温结构演化

Microstructure evolution of TaSi2-MoSi2 based thermal protecting coatings with high emissivity

摘要:

本文以硅化钽、硅化钼、硼硅玻璃粉为原料,1200℃短时烧结制备了耐高温热防护涂层。然后采用乙炔焰在1650℃烧蚀涂层2min,自然冷却至室温。利用X射线衍射、扫描电子显微镜和X射线电子能谱研究了该耐高温热防护涂层在1650℃高温加热前后的涂层结构和组分变化。结果显示制备出的热防护涂层表面为Ta2O5和少量TaSi2。经过1650℃短时高温烧蚀后,涂层表面烧蚀中心区形成大量片状Ta2O5,该Ta2O5连成片。涂层截面形貌显示高温烧蚀后涂层接近表面部分发生致密化,厚度约23μm. 涂层截面的元素面扫描分析显示截面上钽、钼元素分布均匀,即涂层具有良好的结构均匀性。

Abstract:

A thermal protecting coating was prepared at 1200 ℃ using TaSi₂, MoSi₂, borosilicate glass powders as the starting materials. Subsequently the thermal protecting coating was heated at 1650℃ for 2 min and cooled naturally to room temperature. The microstructures and composition of the thermal protecting coating before and after heated at 1650℃ were measured by XRD, SEM and EDS. It is found that the surface of the as-prepared thermal protecting coating contained Ta₂O₅ and small amount of TaSi₂. Lots of Ta₂O₅ sheets were formed in the heating center region of the coating surface after the heating of 1650℃. The section of the coating close to the surface became dense after heating at 1650℃, and the thickness of the dense section was about 23 μm. There is an even distribution for Ta and Mo elements in the element mapping of coating section, that is, the composition of the thermal protecting coating is uniformed.