基于界面调控的真空钎焊金刚石复合涂层制备与温度影响机制研究

Fabrication of Vacuum Brazed Diamond Composite Coatings via Interface Regulation and Temperature Influence Mechanism

摘要:

新疆地区土壤以砂石混合质地为主,农机触土部件在作业过程中常面临严重的磨粒磨损问题,导致其使用寿命缩短和作业效率降低。为解决传统耐磨涂层结合强度低、易剥落等问题,本研究采用真空钎焊技术,在34MnB5钢基体上制备了由Ni60AA钎料与金刚石颗粒复合的耐磨涂层,并系统研究了不同钎焊温度(1010~1110℃)对涂层界面结构、硬度及耐磨性能的影响机制。实验结果表明,随着钎焊温度的升高,涂层中的金刚石颗粒出现上浮现象,并且金刚石与钎料界面处逐渐形成由Cr3C2和Cr7C3组成的碳化物过渡层。当温度达到1 050℃时,金刚石与钎料的界面结合最为理想,此时涂层硬度达到68.2 HRC,磨损量降至最低(9.3 mg),表明在该温度下涂层的耐磨性能最好。当钎焊温度过低时(如1 010℃),金刚石与钎料的界面反应不充分,导致结合力弱,磨损加剧;而当温度过高时(≥1 070℃),金刚石表面石墨化现象加剧、碳化物层过厚,从而导致金刚石与钎料的界面结合强度降低,涂层硬度与耐磨性能也随之下降。本研究揭示了真空钎焊温度通过调控界面碳化物的形成以及金刚石的石墨化行为,显著影响了涂层的力学性能与耐磨性。

Abstract:

Soil in the Xinjiang region is predominantly a sandy-loam mixture, which subjects agricultural machinery components in contact with the soil to significant abrasive wear, thereby shortening their service life and reducing operational efficiency. To address the issues of low bonding strength and delamination in traditional wear-resistant coatings, vacuum brazing technology was employed to fabricate the composite wear-resistant coating consisting of Ni60AA brazing alloy and diamond particles on the 34MnB5 steel substrate. The effects of various brazing temperatures (1 010~1 110℃) on the coating’s interface structure, hardness, and wear resistance were systematically investigated. The results indicated that as the brazing temperature increased, the diamond particles in the coating exhibited a tendency to rise, and a carbide transition layer composed of Cr3C2 and Cr7C3 gradually formed at the interface between the diamond and the brazing alloy. At a brazing temperature of 1 050℃, the interface bond between the diamond and brazing alloy was found to be optimal, resulting in a coating hardness of 68.2 HRC and the lowest wear loss (9.3 mg), corresponding to the best wear resistance. At lower brazing temperatures (e.g., 1 010℃), the interface reaction between the diamond and the brazing alloy was incomplete, resulting in weak bonding and increased wear. Conversely, at higher brazing temperatures (≥1 070℃), the diamond surface experienced more pronounced graphitization, and the carbide layer became overly thick, leading to a weakened interface bond strength and, consequently, a decrease in both coating hardness and wear resistance. The research result revealed that the brazing temperature significantly influenced the mechanical properties and wear resistance of the coating by controlling the formation of interface carbides and the graphitization behavior of the diamond.