Ni含量对NiCrN涂层腐蚀磨损机理的影响

为了提高农业机械部件的腐蚀磨损性能,采用电弧离子镀技术在42CrMo钢基体上制备NiCrN涂层,系统研究Ni含量对涂层结构、力学性能以及腐蚀磨损性能的影响。结果表明:通过调节靶材组分实现涂层中Ni含量(原子数分数)的变化(35.9%～67%)。涂层物相主要由金属Ni相、Cr_2N及CrN陶瓷相组成。随着涂层中Ni含量增加,涂层与基体结合强度提高,而涂层硬度从759 HK0.025降低至566 HK0.025。根据腐蚀磨损动力学曲线可知:随着涂层中Ni含量增加,涂层失重速率先降低后升高,44.1%Ni涂层失重速率最低,耐腐蚀磨损性能最佳。在腐蚀磨损过程中,腐蚀介质以涂层中贯穿性缺陷作为腐蚀通道与基体发生接触,使得腐蚀优先发生在膜-基界面的基体上。腐蚀与磨损存在明显的交互作用,加速了涂层的失效。

Effects of Ni Content on Corrosive Wear Mechanism for NiCrN Coatings

To improve the corrosive wear performances of agricultural machine components, NiCrN coatings were deposited on 42CrMo substrates via arc ion plating technology. The effects of Ni content on microstructures, mechanical properties and corrosive wear performances of NiCrN coatings were systematically investigated. The results show that Ni content in NiCrN coatings changes from 35.9% to 67% by means of manipulating target compositions. NiCrN coatings are mainly composed of metallic Ni, Cr₂N and CrN ceramic phases. With increasing of Ni content, the adhesion strength is improved, while the microhardness decreases from 759 HK_0.025 to 566 HK_0.025. The coating mass loss rate firstly decreases and then increases with increasing of Ni content based on the kinetic curves of corrosive wear experiments, and the coating with 44.1% Ni exhibits the minimum mass loss and the optimal corrosive wear resistance. Corrosive medium arrives at the coating-substrate interface and erodes the substrate preferentially by penetrated defects in the coatings which acts as the medium transport channels. Moreover, the synergistic effects between corrosion and wear accelerate the failure of the coatings.