化学活化诱导碳化物陶瓷粉体表面生长金属层及其应用研究

发布时间：2018-05-31 07:47

本文选题：碳化物陶瓷-金属复合粉体 + 化学活化预处理　；参考：《浙江理工大学》2015年硕士论文

【摘要】：激光熔覆技术的基础是制备性能优良的喂料粉体。化学镀是制备金属包覆型复合粉体的先进方法，其制备的复合粉体有效润湿了陶瓷粉体，实现了粉体颗粒均匀分散，且粒径大小和金属包覆量均可控，有效解决了传统复合粉体制备过程中的团聚和混合不均匀问题，为性能优良的涂层制备奠定了基础。本文采用化学活化对碳化物陶瓷粉体进行预处理，不同于传统陶瓷粉体催化活化机理，以新生的表面缺陷作为活性中心，然后利用低温超声化学镀的方法将金属直接沉积在其表面，缩短了陶瓷-金属复合粉体生产工序、降低了生产成本、提高了复合粉体质量。采用化学活化低温超声化学镀工艺，在WC和SiC陶瓷粉体表面均匀包覆了金属Ni、Ag层，制备了不同粒径大小的WC-Ni、WC-Ag、SiC-Ni等碳化物陶瓷-金属复合粉体。碳化物陶瓷粉体本身均具有一定的表面催化活性，WC陶瓷粉体由于表面独特的电子结构，本身催化活性较强，不经过化学活化预处理也能够启动化学镀。碳化物陶瓷粉体经化学活化后，新生的表面缺陷与粉体表层特殊的电子结构复合增强其表面催化活性，不仅提高了镀层均匀性，而且增强了两相间的结合。以新生缺陷为形核中心，，还原金属Ni (Ag)沿三维生长方式均匀铺满碳化物陶瓷粉体表面，最终形成包覆完整的陶瓷-金属芯核结构复合粉体。采用化学活化低温超声化学镀制备的WC-Ni复合微粉为喂料粉体，利用CO2激光熔覆在45钢基体表面制备性能优良的耐磨损涂层，获得了WC颗粒均匀分布的枝晶状熔覆层组织，涂层与基体之间属冶金结合，结合非常牢固。涂层试样的硬度显著提高，最高硬度接近1200HV。涂层的比磨损率比基体试样的下降了95.8%，45钢基体经激光熔覆WC-Ni复合涂层后，抗塑性变形以及粘着磨损的能力得到提高，其磨损特征主要表现为磨粒磨损。
[Abstract]:Laser cladding technology is based on the preparation of fine feed powder. Electroless plating is an advanced method for the preparation of metal coated composite powders. The composite powders are effectively wetted and dispersed uniformly, and the particle size and the amount of metal coating can be controlled. The problem of agglomeration and mixing inhomogeneity in the preparation of traditional composite powders is effectively solved, which lays a foundation for the preparation of coatings with excellent properties. In this paper, the pretreatment of carbide ceramic powder by chemical activation is different from the catalytic activation mechanism of traditional ceramic powder, and the new surface defects are used as the active center. Then the metal was deposited directly on its surface by low temperature ultrasonic electroless plating, which shortened the production process of ceramic and metal composite powder, reduced the production cost and improved the quality of composite powder. The surface of WC and SiC ceramic powders was uniformly coated with NiAg-Ag layer by chemically activated low-temperature ultrasonic electroless plating. Carbide ceramics and metal composite powders were prepared with different particle sizes of WC-NiOWC-AgSiC-Ni. The carbide ceramic powders have a certain surface catalytic activity. Because of the unique electronic structure of the surface, the carbide ceramic powders have strong catalytic activity and can start electroless plating without chemical activation pretreatment. After being chemically activated, the surface catalytic activity of the carbide ceramic powder was enhanced by the composite of the new surface defects and the special electronic structure of the powder surface, which not only improved the uniformity of the coating, but also enhanced the bonding between the two phases. Taking the new defect as the nucleation center, the reduction metal Ni + Ag was uniformly covered with carbide ceramic powder surface along the three dimensional growth mode, and finally the composite powder coated with the ceramic core structure was formed. The WC-Ni composite powder prepared by chemical activation low temperature ultrasonic electroless plating was used as the feed powder. The dendrite cladding structure with uniform distribution of WC particles was obtained by CO2 laser cladding on the surface of 45 steel. It is a metallurgical bond between the coating and the substrate, and the bonding is very firm. The hardness of the coating sample was improved remarkably, and the highest hardness was close to 1200 HV. The specific wear rate of the coating is lower than that of the substrate sample. After laser cladding the WC-Ni composite coating, the resistance to plastic deformation and adhesion wear is improved. The wear characteristics of the coating are mainly abrasive wear.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ174.1

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