Ni基合金NiCrAlY/YSZ涂层表面混杂溶胶-凝胶法制备高辐射率SiO2-SiC涂层(英文)

High-Emissivity SiO_2-SiC Hybrid Sol-gel Coatings over YSZ/NiCrAIY Layers for Ni-based Superalloy

采用混杂溶胶-凝胶法在GH4099合金的NiCrAlY/YSZ涂层表面制备高辐射率SiO2:F-SiC涂层。NiCrAlY层和YSZ层采用大气等离子喷涂法制备,高辐射涂层采用浸涂和烧结的方法制备。涂层的组织采用扫描电子显微镜和激光其聚焦显微镜观察,相组成采用XRD分析。采用傅里叶红外辐射测试仪测量500℃下全法向发射率,并计算辐射系数。结果表明,涂层经700、800以及900℃烧结后,SiO2:F呈非晶态,经10次浸涂后烧结得到的SiO2:F-SiC层厚度不均匀,为530μm,而且10次浸涂层问没有出现不连续现象。在SiO2:F-SiC层中有贯穿型裂纹存在,但没有出现剥落现象,表明外涂层和YSZ层间具有合适的结合。涂层在500℃其有较高的辐射系数,822μm波段平均辐射系数达到0.85。

To improve the emissivity,the hybrid sol-gel-based SiO_2-SiC layer applied over YSZ layer and NiCrAlY bond layer for GH_4099 superalloy was prepared.The NiCrAlY bond layer and YSZ layer was fabricated by plasma spraying.The high-emissivity SiO_2-SiC hybrid sol-gel coatings were fabricated by dip-coating and sintering.The morphology of samples was characterized using a scanning electron microscopy and confocal laser scanning microscopy.Phases were identified by the X-ray diffraction analysis.The emissivity at 500 ℃ was measured.The results show that amorphous SiO_2 appears for samples sintered at 700,800 and 900 ℃.A SiO_2-SiC layer thickness of about 5-30 urn is obtained with 10 consecutive dip-coatings without intermediate firings.There is no visible discontinuity at the interfaces between each of the 10 dip-coating layers.The penetrating cracks can be found,but no delamination of the coatings from the YSZ layer is evident,indicating acceptable coating adhesion with YSZ surface.The coatings exhibit high emissivity,with the mean value approaching 0.85 in the bands within 8~22μm.