WC粒径影响等离子体熔覆镍基涂层旋耕刀耐磨性研究

Wear Performance Evolution of Plasma-cladded Nickel-based Coated Rotary Tiller Blades Affected by WC Particle Size

摘要:

为了解决旋耕刀硬度低、耐磨性差,难以满足现代农业对旋耕刀工作性能要求的问题,采用等离子体熔覆技术在65Mn钢基体表面制备镍基碳化钨(WC)增强复合涂层,系统研究不同碳化钨颗粒粒径对涂层微观结构、力学性能及旋耕刀田间磨损行为的影响。通过制备Ni–WC涂层,结合X射线衍射(XRD)、扫描电子显微镜(SEM)、显微硬度测试(显微维氏硬度计)及摩擦磨损试验(湿砂橡胶轮试验),分析涂层的物相组成、组织形貌、硬度和耐磨性;并利用台架试验与田间试验对比不同涂层的旋耕刀磨损。结果表明:50~100 μm的WC颗粒因分散均匀性高,显著细化涂层组织,减少气孔与裂纹缺陷;涂层的平均硬度为1 155.7 HV0.5,是基体硬度的4倍。在相同工况下的湿砂橡胶轮磨损试验中,涂层的磨损损失量为65Mn钢的47.61%,磨损形貌由粘附磨损转变为磨料磨损。利用台架试验验证田间试验的可用性,田间试验表明涂层刀具在耕作37.7 hm2旱田后磨损损失量降低19%。涂层提升了旋耕刀的硬度、耐磨性及强度。

Abstract:

Aiming to address the drawbacks of rotary tiller blades, including low hardness and poor wear resistance, which failed to meet the performance requirements of rotary tiller blades in modern agriculture, plasma cladding technology was adopted to fabricate nickel-based tungsten carbide ( WC) reinforced composite coatings on the substrate surface of 65Mn steel. The effects of WC particles with different particle sizes on the microstructure, mechanical properties and field wear behavior of coated rotary tiller blades were systematically investigated. Ni – WC composite coatings were prepared and characterized by X-ray diffraction (XRD), scanning electron microscopy ( SEM), microhardness tests ( Vickers microhardness tester ) and wet sand rubber wheel abrasion tests to analyze the phase composition, microstructure morphology, microhardness and wear resistance of the coatings. Bench tests and field trials were further carried out to compare the wear loss of rotary tiller blades coated with different composite coatings. The results showed that WC particles sized 50~100 μm exhibited excellent dispersion uniformity, which significantly refined the coating microstructure and reduced pore and crack defects. The average microhardness of the coating reached 1 155.7 HV0.5, approximately four times of that of the 65Mn substrate. In wet sand rubber wheel abrasion tests under identical working conditions, the mass wear loss of the coating was only 47.61% of that of the 65Mn substrate, and the dominant wear mechanism shifted from adhesive wear to abrasive wear. Bench tests verified the reliability of field trial results. Field experiments demonstrated that the wear loss of coated blades was decreased by 19% after ploughing 37.7 hm2 of dry farmland. The composite coating effectively improved the hardness, wear resistance and structural strength of rotary tiller blades.