结晶器铜板表面激光熔覆耐磨涂层的研究

发布时间：2018-09-14 15:49

【摘要】：本课题以铬锆铜合金为基体,Ni60粉末及WC质量分数为10%、20%、30%的Ni60+WC混合粉末作为熔覆材料,采用激光熔覆技术在铬锆铜合金表面制备了4种熔覆层:Ni60、Ni60+10%WC、Ni60+20%WC、Ni60+30%WC。首先,以熔覆层平均硬度为指标,通过正交试验优化熔覆工艺,然后以优化所得工艺参数制备了这4种单道熔覆层,对所制备的熔覆层测试了硬度,通过SEM、EDS研究分析了熔覆层的微观组织、元素分布,采用XRD分析了熔覆层的物相组成。最后,采用优化的工艺参数,搭接率30%制备了多道熔覆层,对多道熔覆层进行了硬度测试、磨擦磨损试验和热震试验,研究了多道熔覆层的性能。研究结果表明,在本课题确定的工艺参数范围内:对于Ni60、Ni60+30%WC熔覆层,熔覆速度对其平均硬度影响程度最大,其次是激光功率的影响程度较大,而送粉速率的影响程度较小。工艺优化后,其平均硬度分别达到886HV、1113HV。对于Ni60+10%WC、Ni60+20%WC熔覆层,激光功率对其平均硬度影响程度最大,而熔覆速度和送粉速率的影响程度较小。工艺优化后,其平均硬度分别达到了952HV、1072 HV。熔覆层与铜合金基体间发生了元素扩散,达到了冶金结合。Ni60熔覆层物相主要有γ-Ni固溶体、Cr7C3、Cr23C6、CrB、Ni3B,Ni60+WC熔覆层中除了有上述物相外,还有WC相。随着WC含量的增加,熔覆层平均硬度增大。多道熔覆层的硬度分布趋势和单道熔覆层大致相同,但是多道熔覆层的硬度值要低于单道的。熔覆层靠近界面处至基体方向,硬度值呈现逐渐降低的趋势。Ni60多道熔覆层硬度850HV约为铜基体硬度的6.5倍,Ni60+30%WC多道熔覆层硬度1047HV约为铜基体硬度的8.1倍,加入WC硬质颗粒后大大提高了熔覆层的硬度。制备的Ni60、Ni60+WC熔覆层耐磨性能优异,Ni60熔覆层的磨损失重大约为铜基体的1/3,而Ni60+WC熔覆层的耐磨性能又优于单纯Ni60熔覆层。在本课题试验中,Ni60+20%WC熔覆层的耐磨性更为优异,其磨损失重大约仅为铜基体的1/5。常温下,铜基体的磨损形式是典型的粘着磨损,且磨损程度较大。Ni60、Ni60+WC熔覆层的磨损形式以磨粒磨损为主,存在轻微的粘着磨损和氧化磨损。制备的Ni60、Ni60+WC熔覆层具有较好的抗热震性能,与铜合金基体冶金结合良好,随着WC含量的增多,熔覆层的抗热震性能变差。
[Abstract]:In this paper, four kinds of cladding layers were prepared on the surface of Cr-Zircon Cu alloy by laser cladding technology, using Ni60 powder and 30% Ni60 WC powder with WC content of 10% and 20% by mass fraction, respectively. Four kinds of cladding layers were prepared on the surface of Cr-Zircon Cu alloy by laser cladding technique. Firstly, the average hardness of the cladding layer was taken as the index, and the cladding process was optimized by orthogonal test. Then, the four kinds of single-pass cladding coatings were prepared by optimizing the process parameters, and the hardness of the cladding coatings was tested. The microstructure and element distribution of the cladding layer were studied by SEM,EDS, and the phase composition of the cladding layer was analyzed by XRD. Finally, the multi-pass cladding layer was prepared by optimizing the process parameters and the lap ratio of 30%. The hardness test, friction wear test and thermal shock test of the multi-pass cladding coating were carried out, and the properties of the multi-pass cladding coating were studied. The results show that the influence of cladding speed on the average hardness of Ni60,Ni60 30%WC cladding layer is the largest, followed by laser power and powder feeding rate. After optimization, the average hardness reached 886 HVV 1113 HV respectively. For the Ni60 10 / WCC Ni 60 20%WC cladding, the laser power has the greatest influence on the average hardness, while the cladding speed and the powder feeding rate have little effect on the average hardness. The average hardness of the optimized process was 952 HVN 1072 HV., respectively. There is element diffusion between the cladding layer and the copper alloy substrate, and the main phases of the metallurgical bonding. Ni60 cladding layer are 纬 -Ni solid solution Cr7C3C6Cr23C6CrBPn3BN60 WC cladding layer. Besides the above phase, there is also the WC phase in the cladding layer. With the increase of WC content, the average hardness of the cladding layer increases. The hardness distribution trend of multichannel cladding layer is similar to that of single cladding layer, but the hardness value of multichannel cladding coating is lower than that of single cladding layer. The hardness of Ni60 multichannel cladding layer is about 6.5 times of that of Cu substrate, and the hardness of Ni60 30%WC multichannel cladding coating is about 8.1 times of that of copper substrate, and the hardness of Ni60 30%WC multichannel cladding layer is about 8.1 times of that of copper substrate, and the hardness of Ni 60 30%WC multichannel cladding layer is about 6.5 times that of Cu substrate. The hardness of the cladding layer was greatly improved by adding WC hard particles. The wear loss of the Ni60,Ni60 WC cladding coating is about 1 / 3 of that of the copper substrate, while the wear resistance of the Ni60 WC cladding coating is better than that of the pure Ni60 cladding coating. The wear resistance of Ni60 20%WC cladding coating is better than that of copper substrate. The wear weight loss of Ni60 20%WC cladding coating is only about 1 / 5 of that of copper substrate. At room temperature, the wear form of copper matrix is typical adhesive wear, and wear degree of Ni60Ni60 WC cladding layer is mainly abrasive wear, there is slight adhesion wear and oxidation wear. The prepared Ni60,Ni60 WC cladding coating has good thermal shock resistance and good metallurgical bond with copper alloy matrix. With the increase of WC content, the thermal shock resistance of the cladding layer becomes worse.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.44

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