【摘要】 采用大气等离子喷涂技术在321不锈钢表面制备了Fe70Ni27B3屏蔽涂层和Fe64Ni20B16/Ni-Al梯度涂层。对两种涂层进行分层研磨后,分别采用机械抛光和电抛光处理,测试了涂层表面及内部不同厚度处的相组成和宏观残余应力。结果表明:涂层中具有中子屏蔽功能的含硼相在Fe70Ni27B3涂层中主要为Fe2B相,含有少量的Fe7B相;在Fe64Ni20B16/Ni-Al梯度涂层中主要为FeB相,有少量的Fe2B相和Fe7B相。两种涂层表面的残余应力均为拉应力,沿涂层向内部的拉应力逐渐减小,至涂层/基体界面附近时转化为压应力。两种残余应力大小均不超过50MPa,而梯度涂层由于减小了界面热失配程度以及降低了硬质铁硼相浓度,其残余应力大小在涂层厚度方向上均小于Fe70Ni27B3涂层。更多还原

【Abstract】 The Fe70Ni27B3 coating and Fe64Ni20B16/Ni-Al functional gradient coating (FGC) were deposited on 321 stainless steel substrate by air plasma spraying (APS). After thinning,fine mechanical polishing (for X-Ray Diffraction analysis) and electro-polishing (for residual stress analysis),the morphology,phases and residual stress in the depth of the two types of coatings were investigated. The results indicate that for the boron density difference of the two coatings,Fe2B and a small quantity of Fe7B exist in Fe70Ni27B3 coating,while FeB,less Fe2B and few Fe7B exist in Fe64Ni20B16/Ni-Al FGC. The Fe-B phases are generally brittle and hard; they strengthen the hardness and wear resistance,and at the same time increase the interface thermal mismatch and residual stress in the coatings. The residual stresses on the top of the coatings are tensile and decrease gradually towards the inner coatings,and then transform into pressure stress in the coatings close to the substrate. The total macro residual stresses of the two types of coating are below 50 MPa. For the relative low Fe-B phase density and interface thermal mismatch of Fe64Ni20B16/Ni-Al (FGC),the residual stresses are lower than those of Fe70Ni27B3 coating.更多还原