【作者】 张发云；

【导师】 蒋建敏；

【作者基本信息】 北京工业大学 ， 材料加工工程， 2007， 硕士

【摘要】 金属陶瓷复合涂层既具有陶瓷的高硬度、耐磨损、耐高温、抗氧化和高的化学稳定性,又具有金属的高韧性和可塑性,是一种较为理想的涂层材料。热喷涂制备金属陶瓷复合涂层的方法有粉末火焰喷涂法、等离子喷涂法、高速火焰喷涂法和电弧喷涂法等。相比其他热喷涂方法,电弧喷涂技术成本低、操作简单,便于现场原位施工、容易调整涂层化学成分。本文采用电弧喷涂含碳化物（TiC、WC、Cr₃C₂）陶瓷粉末的粉芯丝材,在低碳钢基体上制备了铁基陶瓷复合涂层。利用光学显微镜、扫描电子显微镜（SEM）、能谱仪（EDAX）、X射线衍射仪（XRD）等先进测试手段对电弧喷涂层的显微组织结构、磨损表面和相组成进行分析。采用MLS-225型湿砂橡胶轮磨损试验机评价了涂层的耐磨粒磨损性能。并研究了粉芯中碳化物含量、后热处理温度対涂层组织结构和磨损性能的影响。本文研究成果如下:1.采用电弧喷涂含碳化物陶瓷的粉芯丝材,制备铁基陶瓷复合涂层是可行的,并可获得具有优良综合性能的耐磨涂层,其涂层的相对耐磨性是对比样Q235钢的6～18倍。2.系统研究了陶瓷与合金体系的匹配关系,以及陶瓷含量对涂层耐磨性的影响。随着粉芯中陶瓷相（TiC、WC、Cr₃C₂）含量的增加,涂层的显微硬度有所增加,涂层的耐磨损性能逐步提高,当陶瓷含量达到一定含量时,涂层的耐磨损性能又开始降低。3.系统研究了后热处理对涂层性能的影响。随着后热处理温度的升高,涂层的显微硬度逐步增加。但耐磨损性能变化各异,TiC涂层的耐磨损性能逐步增加。WC涂层的耐磨损性能先降后升。Cr₃C₂涂层的耐磨性逐步降低。4.涂层的磨粒磨损在脆性脱落与犁沟切削共同作用下发生。涂层耐磨性好的原因主要是涂层中塑性较好的基体硬度较高,同时在基体中含有一定的碳化物硬质相。随着磨损时间的增加,三种涂层的耐磨损性能增强。更多还原

【Abstract】 Cermet composite coatings have high hardness, wear resistance, high temperature oxidation, corrosion resistance and high chemical stability, also have high toughness and plasticity. Therefore, it’s a perfect coating material. At present, many thermal spraying methods for cermet composite coating have been commonly used, such as powder flame spraying, plasma spraying, HVOF spraying and arc spraying. Compared with several spraying methods, arc spraying has the advantages of easy-adjusting chemical compositions, low cost and operating on site applicable.In this study, iron-based composite coatings were deposited on mild steel substrate by arc spraying cored wire with TiC, WC, Cr₃C₂ ceramic powders. The microstructure, phase compositions and worn surface morphologies of the coatings were examined by means of optical, scanning electron microscopy and X-ray diffraction. The abrasion wear resistance properties were evaluated by MLS-225 wet sand/rubber wheel tester. The effect of carbide ceramic content in cored wire and post heat-treatments on the properties of the coatings was studied. Research results are as follows:1. It is feasible that iron-based composite coatings were deposited on mild steel substrate by arc spraying cored wire with TiC, WC, Cr₃C₂ ceramic powders. The results showed that all coatings exhibited better abrasive wear resistance and about 6～18 times higher than that of the Q235 mild steel.2. The experiment studied the matching of ceramic and alloys system, the influence of ceramic content on the abrasion wear resistance of composite coatings. The results showed that the hardness and the abrasive wear resistance of the coatings increased with increasing the ceramic powders （TiC, WC, Cr₃C₂） in the cored wire. When the content of ceramic reached to certain level, the abrasive resistance of coatings began to decrease. 3 The effect of post heat-treatments on the abrasive wear resistance of the composite coatings was studied. The results showed that the micro-hardness of coatings was improved with the temperature’s increase of post heat-treatment. However, the abrasive resistance of three coatings is different. TiC coatings increase gradually, WC coatings first decline and then increase, and Cr₃C₂ coatings gradually decrease.4. Micro-ploughing and brittle fracture were the major abrasive wear mechanisms of the coatings. The coatings have better abrasive wear resistance because the metallic matrix of the coatings have higher hardness and plasticity. The coatings are obviously reinforced by the carbide ceramic hard particles distributed in the iron-based coating. With the increase of the wear time, the abrasive wear resistance of the three coatings has been enhanced.更多还原