氧乙炔喷焊NiCrBSi-WC涂层激光改性组织及性能影响

Effect of Laser Modification on Microstructure and Properties of NiCrBSi-WC Coating by Oxygen Acetylene Spray Welding

摘要:

采用氧-乙炔火焰喷焊在Q235钢上制备NiCrBSi-WC涂层，使用激光对喷焊层表面改性处理后在电炉中进行固体硼硅共渗。通过SEM、XRD、EDS及显微硬度计等对处理前后涂层组织的微观形貌、物相和显微硬度进行分析，使用摩擦磨损实验机研究对比处理前后各涂层的耐磨性能。结果表明喷焊层表面微孔及夹杂在激光扫描处理后变得平整、致密，涂层主相Ni2.9Cr0.7Fe0.36、FeNi3成分未变，但主相在晶面排列上具有择优取向性且结晶度提高。WC部分分解为W2C、W及C，C被固溶进Ni基中使Cr3C2等碳化物相增多，淬硬层深度达0.25mm，显微硬度提高到909HV，耐磨性能得到提高。在涂层激光重熔的基础上硼硅共渗能够增加Ni3B、Ni2B、NiSi等硼化物及硅化物硬质相，平均摩擦系数由0.583降低为0.428，耐磨性较激光处理后提高近一倍。

关键词:热喷焊;Ni基WC;激光改性;硼硅共渗;耐磨性

Abstract:

Preparation of NiCrBSi-WC coating on Q235 steel was using the oxygen acetylene flame spray welding and use solid borosiliconizing method to modify the surface of the spray welding layer was modified by laser. The microstructure, phase structure and microhardness of the coatings were analyzed by SEM, XRD, EDS and microhardness tester and the wear resistance of the coating before and after treatment by using the friction and wear testing machine. The results show that the surface of the spray welding layer under the laser scanning process become smooth and dense. The main phase Ni2.9Cr0.7Fe0.36 and FeNi3 components of the coating were not changed, but the main phase in the arrangement of crystal plane with the preferred orientation and the crystallinity increased. The WC part is decomposed into W2C, W and C. And C was dissolved into the Ni based and increased Cr3C2 and other carbides, and the wear resistance of the coating was improved. The hardened layer depth is 0.25mm and its microhardness increased to 909HV. On the basis of the laser remelted coating, boronsiliconizing can increase Ni3B, Ni2B, NiSi etc. boride and silicide hard phase, the average coefficient of friction decreased from 0.583 to 0.428, wear resistance than laser treatment increased nearly doubled.

Key words:thermal spray welding; Ni-based WC; laser modification; borosiliconizing; wear resistance