WC颗粒含量对TC4激光沉积耐磨特性的影响机制研究

Influence mechanism of WC particle content on wear resistance of TC4 laser deposition

摘要:

针对TC4钛合金耐磨性能差的缺点,采用激光熔化沉积技术(LMD)进行同步送粉法熔覆复合粉末(3~5μmWC与53~150μmTC4)制备出2mm厚的耐磨强化熔覆涂层。使用光学显微镜(OM)和扫描电镜(SEM)观察并分析熔覆层的显微组织及其元素组成成分,在室温干摩擦往复滑动条件下测试熔覆层的磨损性能并分析其磨损机理。结果表明：熔覆涂层与基体结合性良好,无明显裂纹、气孔等缺陷。随着WC颗粒质量分数增加,(Ti,W)C_1-x逐渐增加并分布在α/β相界和晶界处,熔覆层平均硬度比基体提高34%,硬度最高可达基体的1.49倍。熔覆层磨损体积和磨损系数变化规律一致,呈现为先降低后升高再降低。磨损表现形式为磨料磨损,磨损系数均与基材相近。磨损率随WC颗粒质量分数增加而降低,WC含量10%时熔覆层耐磨性能最好,较基材提升25%。

Abstract:

A In view of the poor wear resistance of TC4 titanium alloy, laser melting deposition technology (LMD) was used to fabricate a 2mm thick wear resistant cladding coating of composite powder (3~5μmWC and 53~150μmTC4) by synchronous powder feeding method. Optical microscope (OM) and scanning electron microscope (SEM) were used to observe and analyze the microstructure and elemental composition of the cladding layer. The wear properties of the cladding layer were tested and its wear mechanism was analyzed under the condition of dry friction reciprocating sliding at room temperature. The results show that the cladding coating has good adhesion to the substrate and no obvious cracks, pores and other defects. With the increase of WC particle mass fraction, (Ti,W)C_1-x increases gradually and distributes at α/β phase boundary and grain boundary. The average hardness of cladding layer is 34% higher than that of matrix, and the hardness is up to 1.49 times of matrix. The wear volume and wear coefficient of the cladding layer change in the same way, decreasing first, then increasing and then decreasing. The wear is abrasive wear, and the wear coefficient is close to the base material.The wear rate decreases with the increase of WC particle mass fraction. When WC content is 10%, the wear resistance of cladding layer is the best, which is 25% higher than that of base material.