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使用激光近净成形方法,在Ti-6Al-4V基板上进行高纯Al2O3成形实验,分别制备出黑色和白色Al2O3薄壁样品。利用扫描电子显微镜观察样品截面微观组织并检测截面化学元素。利用X射线衍射仪分析原始Al2O3粉末、黑色样品和白色样品的物相组成、成色原因以及成形件样品表面裂纹数量与颜色之间的关系。结果表明:黑色薄壁样品表面裂纹数量多、分布均匀;白色薄壁样品仅中上部含有极少量裂纹。成形工艺可显著影响陶瓷粉末中杂质氧化物的挥发程度,进而影响成形件样品元素组成及物相。次晶相的出现是成形件样品颜色发黑的根本原因,并加剧了黑色样品表面裂纹的产生与扩展。
Near-net-shape laser was used to fabricate high-purity Al2O3 on Ti-6Al-4V substrates. Black and white Al2O3 thin-wall samples were prepared. Scanning electron microscopy was used to observe the cross-section microstructure of the sample and to examine cross-section chemical elements. The relationship between the phase composition of the original Al2O3 powder, the black sample and the white sample, the reason of the color formation and the number of surface cracks and the color of the sample were analyzed by X-ray diffraction. The results show that there are many cracks on the surface of black thin wall samples and the distribution is even. The white thin wall samples contain only a few cracks in the middle and upper part. Forming process can significantly affect the volatility of the oxide in the ceramic powder, thereby affecting the shape of the sample elemental composition and phase. The appearance of the secondary crystalline phase is the root cause of the blackening of the sample of the shaped part and exacerbates the generation and expansion of the crack on the surface of the black sample.