不同循环周期Cr/NiCrN多层涂层腐蚀磨损行为

The Corrosive Wear Behavior of Cr/NiCrN Multilayer Coatings with Various Cycle Periods

目的在低碳钢表面制备硬质涂层,以提高其腐蚀磨损性能。方法使用电弧离子镀制备技术在低碳钢基体(42CrMo)表面沉积Cr/NiCrN多层涂层,在保持涂层厚度基本一致的前提下,通过改变子层沉积时间来调控涂层循环周期(分别为1、5、10、15)。通过扫描电子显微镜及X射线衍射仪研究涂层的微观组织结构,并利用洛氏、维氏硬度计以及自制的腐蚀磨损试验机分别评价涂层的力学性能及腐蚀磨损性能。结果不同循环周期下,Cr/NiCrN多层涂层物相组成基本相同,主要包括Ni和Cr金属相、CrN陶瓷相以及少量Cr_(2)N相。随着循环周期从1增加至15,涂层的结合强度提高,显微硬度从882HK_(0.025)逐渐上升为964HK_(0.025)。经过磨损、腐蚀16h后,4种涂层试样的磨损、腐蚀失重分别占腐蚀磨损失重的12%~14%和61%~77%,其中,循环周期为15的Cr/NiCrN多层涂层显示出最佳的腐蚀、磨损及腐蚀磨损性能。结论由于多层涂层具有"自愈"作用,能显著减少贯穿性腐蚀通道的数量,同时Cr-NiCrN界面的存在起到了增强、增韧和延长腐蚀介质传输路径的作用,因此随着循环周期的增加,涂层的腐蚀磨损性能提高。此外,涂层在腐蚀磨损过程中还存在一定的交互作用。

Hard coatings are always utilized to enhance surface performances of mild steels.In this paper,Cr/NiCrN multilayer coatings were fabricated on 42CrMo steel substrates by means of arc ion plating technology to improve corrosive wear resistances of low carbon steels.The cycle periods(1,5,10 and 15)were manipulated by varying the sublayer deposition time,while the overall coating thickness kept basically the same.Multiple detection methods including scanning electron microscope and X-ray diffraction were used to investigate the coating microstructures.Besides,Rockwell and Vickers hardness testers as well as self-made corrosive wear apparatus were applied to evaluate the coating mechanical properties and corrosive wear performances respectively.The results clearly show that Cr/NiCrN multilayer coatings with various cycle times exhibit similar phase structures,including Ni,Cr metallic phases,CrN ceramic phase as well as a small amount of Cr_(2)N phase.As the cycle period increases from 1 to 15,the coating adhesion is improved,and the microhardness is enhanced slightly from 882HK0.025 to 964HK0.025 as well.After wear and corrosion test for 16 h,the sample wear weight loss accounts for 12%~14%of the corrosive wear weight loss,while the corrosion weight loss accounts for 61%~77%.The Cr/NiCrN multilayer coating with 15 cycle periods reveals the best corrosion,wear and corrosive wear resistance.The coating corrosive wear resistance is improved with increasing in cycle periods.The reason is that,firstly,the multilayer structure exhibits“self-healing”effect,which could significantly reduce the numbers of penetrating corrosion channels.Secondly,Cr-NiCrN interfaces play an important role in strengthening and toughening of the coatings,as well as elongating the transmission routs of the corrosive medium during the corrosive wear experiments.As a result,the corrosive wear performance of the coated material improves as the cycle periods increases.In addition,the interactions between corrosion and wear are identified in the process of corrosion and wear experiments.