ISSN   1004-0595

CN  62-1224/O4

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硬质合金表面织构液相辅助激光制备及摩擦性能

Liquid-Phase Assisted Laser Preparation of Cemented Carbide Surface Textures and Study on Their Tribological Properties

  • 摘要: 采用激光加工技术在空气介质与辅助液相(无水乙醇与双氧水体积比为50:1)下对YT15硬质合金表面进行了交叉扫描织构加工,制备出了两组织构试样. 借助Quanta 200扫描电子显微镜及能谱对织构硬质合金表面形貌与元素含量进行了测量,并用SDC-100接触角测量仪表征了润湿性,最后在MWF-500往复式摩擦磨损试验机上进行了干摩擦、润滑油及润滑油与MoS2颗粒润滑的摩擦和磨损对比试验. 研究结果表明:相比空气介质激光加工试样,液相辅助激光加工表面的微凹坑分布更加均匀,无明显的氧化及熔融物重铸现象,表面接触角最小(55°);三种工况下液相辅助激光加工表面织构的摩擦系数最小,磨损量有一定改善. 分析表明:辅助液体对激光加工表面起到了冷却及保护作用,固-液界面快速产生的气泡散射了激光光束,使激光光束的作用区域发生干涉,同时携带出加工熔融物. 因此,润滑介质更容易在界面间渗入及铺展,改善了界面摩擦学特性.

     

    Abstract: Surface texture, as an effective approach to improve lubrication and tribological characteristics at the sliding interface, was introduced into the tool manufacturing process. In order to improve the thermal effect and melt recast phenomenon of laser processing method on cement carbide surface, liquid-phase assisted laser processing method was introduced in this study. Two groups of textured type were prepared on YT15 cemented carbide surface using laser cross scanning method under air medium and auxiliary liquid phase (the volume ratio of ethanol to hydrogen peroxide is 50:1) respectively. The surface morphology and element content of test samples were measured with Quanta 200 scanning electron microscope, energy spectrum, and X-ray diffraction, and then the wettability were obtained with SDC-100 contact angle measuring instrument. The subsequent tribological test was carried out using MWF-500 reciprocating friction and wear testing machine under dry sliding, oil, and oil-MoS2 lubrication condition. The results showed that the textured surface of laser processing in air medium was obviously blackened, and the oxygen content increased from 13.35% to 27.9%. TiO and CoO were found on the processed surface. For the laser processing surface with liquid-phase assist, the micro-pits of texture morphology were more uniform than that of air medium case. The oxygen content decreased from 13.35% to 8.63%, and no obvious oxidation and melt recasting phenomenon were found. The wettability of cemented carbide surface was improved due to better surface texture processing quality. Under three lubrication conditions, the friction coefficient of textured sample prepared under liquid-phase assisted environment was the smallest. The friction coefficient in oil lubrication, was reduced by 34% and 28%, compared to the original surface and laser processing surface in air, respectively. It indicated that the laser processing surface with liquid-phase assist has obvious advantages in regulation the interfacial friction and wear. The main reason was that the auxiliary liquid played a key role in cooling and protecting action of the machined surface. The bubbles, generating at the solid-liquid interface due to the laser heat effect, scattered the laser beam and carried out the processed melt meanwhile. Thus, the lubricating medium was easier to penetrate and spread between the contact interfaces, and the tribological characteristics was improved. The main contribution of this work was in providing a new processing method to prepare surface texture of better surface micro-pits quality and interfacial regulation of friction and wear.

     

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