纯铁表面激光熔覆Fe-Cr-Si-B-C非晶粉末的研究

发布时间：2018-05-10 07:54

本文选题：激光熔覆 + Fe基非晶合金　；参考：《辽宁科技大学》2015年硕士论文

【摘要】：用激光熔覆技术可以在普通基体材料表面制备稀释率低与基体结合良好的冶金涂层,提高基体表面的强度、硬度、耐磨损、耐腐蚀等性能。本论文采用HGL-6000型横流CO2激光器在工业纯铁基体上采用Fe-Cr-Si-B-C非晶粉末激光熔覆制备冶金涂层,分析激光工艺参数对涂层的微观组织、显微硬度的影响;利用金相显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、显微硬度计等对涂层的组织结构、相组成、微区成分、显微硬度进行了分析;并用电化学工作站和摩擦磨损试验机等对涂层的耐腐蚀及耐磨损性能进行了测试和分析。研究表明,熔覆层表面质量良好,具有一定的厚度,表面光滑平整,组织均匀致密;熔覆层没有非晶相形成,形成了简单的α-Fe(BCC)固溶体,并有细小的Fe2B相析出。随着激光功率的增大,涂层的稀释率和形状系数呈现递增趋势;涂层与基体的界面处平面晶界宽度逐渐增加,激光功率在2500W-3500W范围时,随着激光功率的增大,结合区组织逐渐变得细小;当激光功率达到4000W时,结合区组织又变得粗大;随激光功率的增大,显微硬度值降低;随着扫描速度的增大,涂层的稀释率和形状系数呈现递减趋势;树枝晶尺寸逐渐细小,而且外延生长层厚度也随之较小;显微硬度值随扫描速度的增大而增加。当激光功率为3500W,扫描速度为540mm/min时,涂层腐蚀电流平均低至10-6A/cm2,自腐蚀电位为-0.522V,耐腐蚀性能良好;显微硬度最高达到796HV0.2,是钢轨U75V硬度的2.5倍;在载荷、摩擦速度、磨损时间相同的条件下,熔覆层的损失量最小,线性摩擦因数在4N时分别为0.163和-0.171,在8N时分别为0.186和-0.191,摩擦过程也较平稳,耐磨性能良好。
[Abstract]:The metallurgical coating with low dilution and good combination with the substrate can be prepared by laser cladding technology, which can improve the strength, hardness, wear resistance and corrosion resistance of the substrate surface. In this paper, HGL-6000 type transverse flow CO2 laser is used to prepare metallurgical coating on industrial pure iron substrate by Fe-Cr-Si-B-C amorphous powder laser cladding. The effect of laser process parameters on the microstructure and microhardness of the coating is analyzed. The microstructure, phase composition, micro-area composition and microhardness of the coating were analyzed by means of X-ray diffractometer, scanning electron microscope (SEM) and microhardness meter. The corrosion resistance and wear resistance of the coatings were tested and analyzed by electrochemical workstation and friction and wear tester. The results show that the cladding layer has a good surface quality, a certain thickness, a smooth and smooth surface, a uniform and compact microstructure, and no amorphous phase formed in the cladding layer, forming a simple 伪 -FeBCC solid solution, and fine Fe2B phase precipitates. With the increase of laser power, the dilution rate and shape coefficient of the coating increase, the width of grain boundary at the interface between the coating and the substrate increases gradually, and the laser power increases with the increase of laser power in the range of 2500W-3500W. The microstructure of the binding zone becomes smaller gradually; when the laser power reaches 4000W, the structure of the binding zone becomes coarse again; with the increase of laser power, the microhardness decreases; with the increase of scanning speed, the microhardness decreases, and the microhardness decreases with the increase of laser power. The dilution rate and shape coefficient of the coating decrease gradually; the dendrite size is smaller and the thickness of the epitaxial growth layer is smaller; the microhardness value increases with the increase of scanning speed. When the laser power is 3500W and the scanning speed is 540mm/min, the average corrosion current of the coating is as low as 10 ~ (-6) A / cm ~ (2), the corrosion potential is -0.522 V, the corrosion resistance is good, the microhardness is up to 796HV0.2, which is 2.5 times of the rail's U75V hardness. Under the condition of the same wear time, the loss of the cladding layer is the least, the linear friction coefficient is 0.163 and -0.171 at 4N and 0.186 and -0.191 at 8N, the friction process is stable and the wear resistance is good.
【学位授予单位】：辽宁科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.4

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