【摘要】：實(shí)驗(yàn)選用氧乙炔火焰噴涂工藝在三牙輪鉆頭用鋼20CrMo基體上制備鈷基自熔合金粉末涂層,然后使用正交實(shí)驗(yàn)法來研究各實(shí)驗(yàn)工藝參數(shù)對涂層性能的影響,選出最優(yōu)工藝參數(shù)制備涂層后進(jìn)行氬弧重熔處理,探討重熔前后涂層組織與性能的變化,分析不同的粉末成分配比對重熔層的組織及力學(xué)性能的影響,找出最優(yōu)合金粉末成分用于三牙輪鉆頭的強(qiáng)化及修復(fù)。實(shí)驗(yàn)結(jié)果表明：火焰噴涂層和基體之間主要結(jié)合方式為機(jī)械結(jié)合,伴有少量的冶金結(jié)合。涂層呈典型的層狀結(jié)構(gòu),由扁平變形粒子、氧化物夾雜、未熔顆粒和孔隙組成。當(dāng)噴涂層厚度為1.0mm,基體表面粗糙度為6.89μm、噴涂距離為100mm時(shí),涂層綜合性能最好,影響綜合性能的工藝參數(shù)主次關(guān)系為噴涂距離、涂層厚度、基體表面粗糙度�；鹧鎳娡繉咏�(jīng)過鎢極氬弧重熔處理后,重熔層與基體呈冶金結(jié)合,組織致密,孔隙率低,結(jié)合強(qiáng)度顯著提高。重熔層分為重熔區(qū),結(jié)合區(qū),熱影響區(qū)。結(jié)合區(qū)以平面晶和粗大胞狀晶形式生長,結(jié)合區(qū)附近的重熔區(qū)組織為相對較粗的柱狀晶,重熔層心部為大小均勻的柱狀晶和樹枝晶,表層為細(xì)小的樹枝晶和等軸晶,熱影響區(qū)為魏氏體組織,組織較為粗大。鈷基復(fù)合粉末重熔層由γ-Co固溶體和(Cr, Fe)_7C_3、Cr_(23)C_6、Co_6W_6C、WC等相組成。采用重熔處理使噴涂層的硬度、耐磨性等力學(xué)性能明顯增加,當(dāng)鈷基自熔合金粉末中WC加入量為15%,鉻鐵加入量為10%時(shí),重熔層具有最好的硬度和耐磨性,洛氏硬度最大值為HRC67.7、顯微硬度為HV927.3,最少磨損失重量為0.02g；其耐蝕性也相對較好,腐蝕失重量為0.09g。本文選擇最優(yōu)工藝參數(shù)為涂層厚度為1.0mm,基體表面粗糙度為6.891μm、噴涂距離為100mm,最優(yōu)粉末成分為15%WC、10%鉻鐵的鈷基合金復(fù)合粉末對三牙輪鉆頭進(jìn)行強(qiáng)化和修復(fù)。
[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 緯-Co solid solution and (Cr, Fe) _ 7C 鈮，

本文編號：2472607