氩弧重熔对Co60火焰喷涂层组织与性能的影响

发布时间：2019-05-09 08:06

【摘要】：实验选用氧乙炔火焰喷涂工艺在三牙轮钻头用钢20CrMo基体上制备钴基自熔合金粉末涂层,然后使用正交实验法来研究各实验工艺参数对涂层性能的影响,选出最优工艺参数制备涂层后进行氩弧重熔处理,探讨重熔前后涂层组织与性能的变化,分析不同的粉末成分配比对重熔层的组织及力学性能的影响,找出最优合金粉末成分用于三牙轮钻头的强化及修复。实验结果表明：火焰喷涂层和基体之间主要结合方式为机械结合,伴有少量的冶金结合。涂层呈典型的层状结构,由扁平变形粒子、氧化物夹杂、未熔颗粒和孔隙组成。当喷涂层厚度为1.0mm,基体表面粗糙度为6.89μm、喷涂距离为100mm时,涂层综合性能最好,影响综合性能的工艺参数主次关系为喷涂距离、涂层厚度、基体表面粗糙度。火焰喷涂层经过钨极氩弧重熔处理后,重熔层与基体呈冶金结合,组织致密,孔隙率低,结合强度显著提高。重熔层分为重熔区,结合区,热影响区。结合区以平面晶和粗大胞状晶形式生长,结合区附近的重熔区组织为相对较粗的柱状晶,重熔层心部为大小均匀的柱状晶和树枝晶,表层为细小的树枝晶和等轴晶,热影响区为魏氏体组织,组织较为粗大。钴基复合粉末重熔层由γ-Co固溶体和(Cr, Fe)_7C_3、Cr_(23)C_6、Co_6W_6C、WC等相组成。采用重熔处理使喷涂层的硬度、耐磨性等力学性能明显增加,当钴基自熔合金粉末中WC加入量为15%,铬铁加入量为10%时,重熔层具有最好的硬度和耐磨性,洛氏硬度最大值为HRC67.7、显微硬度为HV927.3,最少磨损失重量为0.02g；其耐蚀性也相对较好,腐蚀失重量为0.09g。本文选择最优工艺参数为涂层厚度为1.0mm,基体表面粗糙度为6.891μm、喷涂距离为100mm,最优粉末成分为15%WC、10%铬铁的钴基合金复合粉末对三牙轮钻头进行强化和修复。
[Abstract]:Cobalt-based self-fluxing alloy powder coating was prepared on steel 20CrMo substrate for three-cone bit by oxyacetylene flame spraying process, and then the effect of experimental parameters on the properties of the coating was studied by orthogonal experiment. The optimum process parameters were selected to prepare the coating for argon arc remelting. The changes of microstructure and properties of the coating before and after remelting were discussed, and the effects of different powder distribution ratios on the microstructure and mechanical properties of the remelted layer were analyzed. The optimal alloy powder composition is found out for the strengthening and repair of three-cone bit. The experimental results show that the main bonding mode between flame spray coating and substrate is mechanical bonding, accompanied by a small amount of metallurgical bonding. The coating is a typical layered structure consisting of flat deformed particles, oxide inclusions, unmelted particles and pores. When the coating thickness is 1.0 mm, the surface roughness of the substrate is 6.89 渭 m and the spraying distance is 100mm, the comprehensive properties of the coating are the best. The main and secondary relationship between the coating thickness and the substrate surface roughness is the spraying distance, the coating thickness and the surface roughness of the substrate. After the flame spraying coating is remelted with tungsten argon arc, the remelting layer is metallurgical bonded with the matrix, the microstructure is dense, the porosity is low, and the bonding strength is improved obviously. The remelting layer is divided into remelting zone, joint zone and heat affected zone. The bonding zone grows in the form of planar and coarse cellular crystals. The microstructure of the remelting zone near the bonding zone is a relatively coarse columnar crystal, the core of the remelting layer is a uniform columnar crystal and dendrite, and the surface layer is a fine dendrite and equiaxed crystal, and the structure of the remelting zone near the bonding zone is composed of relatively coarse columnar crystals and dendrites of uniform size. The heat affected zone is Wei body structure, and the microstructure is coarse. The remelting layer of cobalt-based composite powder is composed of 纬-Co solid solution and (Cr, Fe) _ 7C 鈮，

本文编号：2472607