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基材为普通碳钢,涂层为镍基Cr(14～18％)B(3.0～4.5％)Si(3.5～5.5％)系固溶粉末,采用氧——乙炔焰热喷涂工艺。垂直于涂层表面切取试样薄片手工研磨至小于100μ,用离子轰击制成薄膜,在120～200KV下作电镜观察。利用X射线衍射进行相分析,电子衍射测定相结构。主要结果如下; 1.涂层与基材间同时存在机械与化学两种结合方式。基材和涂层交界处存在一个约20μ宽的过渡带,观察到涂层中多种相变产物,它们对涂层的力学性能有着不同的贡献。形成的主要相为:硼化物:NiBn(b.c.c),Ni_4B_3(正交),NiB(正交),Ni_3B(正交);硅化物:Ni_3Si(面心有序),Ni_(31)Si_(12)(六方);碳化物:Cr_7C_3(六方),Cr_(23)C_6(f.c.c)。这些相分布不均,常聚集成团出现,反映出涂层的形成是一个不连续的相变过程。(图A→E)。
The substrate is a common carbon steel, and the coating is a nickel-based Cr (14~18%) B (3.0~4.5%) Si (3.5~5.5%) solute powder, adopting an oxygen-acetylene flame spraying process. Cut perpendicular to the coating surface of the sample slice manual grinding to less than 100μ, with ion bombardment made of thin film, at 120 ~ 200KV for electron microscopy. Phase analysis was performed by X-ray diffraction, and phase structure was measured by electron diffraction. The main results are as follows: 1. There is a combination of mechanical and chemical bonding between the coating and the substrate. There is a transition zone of about 20μ wide at the interface between the substrate and the coating. Various phase-change products in the coating are observed, which have different contributions to the mechanical properties of the coating. The main phases are: borides: NiBn (bcc), Ni_4B_3 (orthogonal), NiB (orthogonal), Ni_3B (orthogonal); silicide: Ni_3Si ) (Hexagonal); Carbides: Cr_7C_3 (hexagonal), Cr_ (23) C_6 (fcc). The uneven distribution of these phases, often clusters into clusters, reflecting the formation of the coating is a discontinuous phase change process. (Figure A → E).