同步送粉等离子束表面冶金合金化涂层的凝固组织特性及形成机理  

Solidification characteristics and mechanism of feeding surface metallurgical coating by DC-plasma-jet

作　　者：李敏[1] 李惠东[1] 李惠琪[1] 裴中爱[2] 孙玉宗[2] 

机构地区：[1]北京科技大学材料学院,北京100083 [2]山东科技大学材料学院,山东青岛266510

出　　处：《焊接学报》2006年第3期69-72,共4页Transactions of The China Welding Institution

基　　金：山东省自然科学基金资助项目(Y2002F12);山东省优秀中青年科学家科研奖励基金资助项目(02135057)

摘　　要：采用自行研发的同步送粉式直流放电压缩电弧等离子束表面冶金技术,利用不同粒度、不同密度、不同形状的混合粉末颗粒,在普通低碳钢表面获得了工程厚度的均匀致密的铁基合金涂层。利用OM、SEM、EDS、EMPA及XRD法研究了该合金化涂层的显微组织、物相组成、溶质分布及基材热影响区的凝固组织特征。结果表明,等离子表面冶金合金化涂层对基材具有良好的润湿性,基材表面熔化区的形成使得涂层与基材实现了完全的冶金结合。快速凝固合金化涂层具有分层凝固特征,从底部具有外延生长的平面晶到中部近等轴晶及表层的穗状晶。凝固组织为固溶了大量Cr及少量B、S i的极度过饱和的γ-(Fe,N i)枝晶及枝晶间合金硼碳化物(Cr,Fe)7(C,B)3与γ-(Fe,N i)共晶组织的复相组织。The ferroalloy coatings with powder mixtures of different constituent,different size,different density and different shape were prepared on Q235 steel using the feeding surface metallurgical technology by DC-Plasma-Jet.The composition, microstructure of alloying coating and microstructure transformation of heat-affected zone were investigated using optical microscope,scanning electron microscope,electron microprobe analysis and X-ray diffraction.Results indicated that plasma surface metallurgical coating of Fe-Cr-Ni-B-Si had well wettability,and metallurgical bonding was obtained between coating and substrate.The rapid solidifing structure of coating was laminar,from epitaxial planar crystal on the bottom to equiax crystal in the middle to bunchy crystal on the top.The matrix of surface coating was malleable γ-(Fe,Ni) dendritic cyrstal,which was supersaturated solid solution of many Cr and small Ni,B,Si,C elements.And eutectic structure of(Cr,Fe)_7(C,B)_3 and γ-(Fe,Ni) dispersed on interdendrite.Due to heat cycle influenced by plasma beam,the heat-affected zone had two layers,phase transformation zone and recrystallization zone.

关 键 词：等离子束表面冶金 凝固组织特征 铁基合金 

分 类 号：TG174.445[金属学及工艺—金属表面处理]