低压冷喷涂制备Al-Ni-xCr复合涂层及其磨损特性研究

Study on the wear characteristics of Al-Ni-xCr composite coating prepared by low pressure cold spraying

防腐性能较好的铝基涂层存在耐磨性不足的问题。本文设计了Ni粉和Cr粉复合沉积的方法来改善涂层的耐磨性。采用低压冷喷涂技术,制备了一系列Cr含量不同的Al-Ni-xCr复合涂层。通过金相、扫描电镜及X射线衍射等方法分析了复合涂层的微观形貌和成分。采用显微硬度计和磨损仪测试了涂层的显微硬度和磨损曲线,结合磨痕形貌分析了复合涂层的磨损机理。研究得出:低压冷喷涂可实现Al、Cr、Ni三种金属粉的共沉积,并获得致密、均匀的Al-Ni-xCr复合涂层。枝晶状Ni粉沉积率较高,Cr粉沉积率较低。含70 wt.%Cr的混粉涂层中,Cr含量约为31 wt.%。硬质颗粒Cr同时起到夯实涂层的作用,随着Cr含量增加,Al-Ni-xCr复合涂层的致密性提高。Al-Ni-xCr复合涂层的耐磨性能主要来自于Cr而非Ni,且与Cr含量有关。Al-Ni-70Cr复合涂层耐磨性最佳,磨损率仅为Al涂层的1/2。其优异的耐磨性归因于摩擦界面形成了稳定的、较硬的、含Cr量较高的复合氧化膜,抑制了磨损过程。

The Al-based coating has well corrosion resistance,but its wear resistance is poor.In this paper,mixing Ni and Cr powders was designed to improve the wear resistance of the Al-based coating.A series of Al-Ni-xCr composite coatings with different Cr content were prepared by low pressure cold spraying.Their micro-morphology and composition were analyzed by means of metallography,scanning electron microscopy and X-ray diffraction.Their microhardness and wear curve were measured by microhardness tester and wear meter.Their wear mechanism was analyzed according to the microscopic characteristics.The results show that the low pressure cold spraying can achieve the co-deposition of Al,Cr and Ni metal powder.The Al-Ni-xCr composite coating is dense and uniform.Dendrite Ni powder has a higher deposition rate,while Cr powder shows a lower deposition rate.The Cr content in AlNi-70Cr coating is about 31 wt.%.With the increase of Cr content,the densification of Al-Ni-xCr composite coating increases.The wear resistance of Al-Ni-xCr composite coating is mainly related to Cr content rather than Ni.Al-Ni-70Cr composite coating has the best wear resistance,and its wear rate is only 1/2 of that of Al coating.Its excellent wear resistance is attributed to the formation of a stable hard and high Cr-containing composite oxide film at the friction interface,which inhibits the wear process.