摘要
用等离子熔覆预先涂敷于碳钢表面的多层Ni6 0 +TiC涂层 ,得到了无层界梯度TiC熔覆层。采用电子探针面扫描和特征X射线扫描两种方式对熔覆层主要元素的分布进行了分析 ,用图像分析仪对各区域的TiC含量进行了定量测试。结果表明 :从熔覆层底部到顶层 ,TiC的粒径和含量呈梯度变化 ,粒径由底部的 1 2 5～ 2 5 μm增加到表层的 15～ 2 5 μm ,含量由 3%上升到 18% ,TiC的形貌由球状过渡到花瓣状、团簇状 ;熔覆层中的组织亦呈梯度分布 :粗大柱状晶→胞状树枝晶→细小树枝晶 ;熔覆层中Si、Fe依次减小 ,而Ti、Cr依次增加 ,Ni分布较均匀。熔池中TiC颗粒的碰撞、粘结和表面张力偶作用对梯度熔覆层的形成起决定性作用。熔覆层内部无明显层界 ,但存在陶瓷相的微观不均匀性。整个熔覆层的显微硬度亦呈梯度分布。
A functional gradient TiC/Ni alloy composite coating was produced by one step plasma cladding with multilayer pre-placed on carbon steel substrate. The distributions of the main elements in the plasma cladded coating were investigated by EPMA with both face-scanning and characteristic X-ray scanning. The contents of TiC were measured by an image analyzer. The results show that TiC particles exhibit a continuous increase both in size (from 1.25-2.5 μm to 15-25 μm) and in volume fraction ( from 3% to 18%) from the bottom to the top surface, and the morphology changes correspondingly from small globe to coarse flower-like cluster, and the structure of matrix shows gradient distribution from coarse columnar crystal to cellular-dendrites to thin dendrites. Si, Fe elements decrease and Ti, Cr increase progressively, while Ni is relatively uniform from bottom to top surface in the plasma cladded coating. The collision and sintering of TiC particles and force couple effects in the plasma melting bath lead to the formation of the gradient coating. There is no any layer interfaces in the plasma cladded coating, but micro inhomogenety of ceramics phase in the coating is observed. The hardness of the cladded coating has a gradient change, corresponding to the distribution of TiC particles.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2004年第3期74-77,共4页
Transactions of Materials and Heat Treatment
关键词
等离子熔覆
梯度涂层
预涂层
Ceramic materials
Cladding (coating)
Crystals
Nickel
Plasma applications
Titanium carbide
