磁过滤电弧离子镀TiN与N离子注入性能研究

Performance of TiN Coating and N Ion Implantation by Magnetic Filtered Arc Ion Plating

目的研究磁过滤电弧离子镀TiN与N离子注入对金属基体的保护效果。方法采用磁过滤电弧离子镀和离子注入在不锈钢表面分别制备了TiN薄膜与N注入改性层,以及二者的复合膜层。对薄膜的相结构、微观形貌进行了表征,对薄膜进行了极化曲线测试,同时在半球样品表面制备涂层并进行盐雾测试。结果所制备的TiN涂层为(111)晶面择优取向,离子注N预处理后沉积的TiN薄膜,仍保持(111)面的择优取向;电化学测试结果显示,TiN和N离子注入能够使不锈钢基体自腐蚀电位分别提高0.64、0.25 V,TiN薄膜具有最低的维钝电流密度4.9×10^(-6) A/cm^(2),N离子注入+TiN复合薄膜的维钝电流密度与N离子注入样品接近;盐雾试验结果表明,TiN以及N离子注入+TiN复合薄膜样品能够保证铜半球在12h的中性盐雾试验中无明显腐蚀痕迹。结论N离子注入预处理对MFAIPTiN涂层耐蚀性能的提升效果有限,单一的MFAIP TiN涂层便可应用于复杂形状的工程材料表面镀膜,可以增强其抗腐蚀能力,延长使用寿命。

The TiN coating is widely used as an anti-corrosion and wear-resistant protective layer for various materials due to the properties of high hardness,good adhesion,excellent corrosion resistance,and exquisite appearance.Common preparation methods of TiN coating include magnetron sputtering(MS)and arc ion plating(AIP).Magnetic filtration arc ion plating(MFAIP)combines the advantages of MS and AIP,and can provide a coating with high interface bonding strength and smooth surface.N ion implantation is also a surface modification method which helps improve the anti-corrosion performance of the substrate.The work aims to study the morphology,phase structure and anti-corrosion properties of TiN coating by MFAIP and N ion implantation.Two kind of materials were used as the substrate,including 202 stainless steel and copper.The 202 stainless steel(SSL)plate was cut into small square slices of 20 mm×20 mm×2 mm.After cleaning with cleaning agent and ethanol,a ultrasonic machine was used for further cleaning.Then,an air spray gun was used to blow dry SSL samples.The copper hemispheres ofϕ60 were used for testing the effectiveness and corrosion resistance of complex shaped coatings.In the experiment,N ion implantation was added into the substrate,with a Kauffman source with high-purity nitrogen gas(purity>99.999%)as the working gas.The accelerating voltage and the current were 50 kV and 6.2 mA,respectively.Total injection time was 2 hours,and the dose was 2×10^(17) ions/cm^(2).Then,a TiN coating was prepared by magnetic filtered arc ion plating technology.The target material was pure titanium target(titanium content>99.8%),and the working gas was high-purity argon gas(purity>99.999%)and high-purity nitrogen gas(purity>99.999%).Before deposition of TiN thin film,the substrate surface was cleaned with glow discharge plasma for 30 minutes to remove the oxide layer on the surface.Then,an inner layer of Ti was pre-deposited to enhance the adhesion between the TiN thin film and the substrate.Finally,a TiN coating was deposited for about 5 hours.The thickness of the film was measured by the KLA Tencor D-300 step tester from the United States.The hardness was measured by a micro-Vickers hardness tester under a pressure of 10 g force and a holding time of 10 s.The surface morphology was observed by OLYMPUS BX51M metallographic microscope and Thermo Helios G4 UC scanning electron microscope,respectively.The coating phase structure was tested by an Empyrean X-ray diffractometer from the Netherlands in a small angle diffraction mode with an incidence angle of 2°,a scanning range of 10°~80°,a scanning step of 0.04°,and a scanning speed of 6(°)/min.Electrochemical testing was conducted on the CHI760 electrochemical workstation with a 0.5 mol/L NaCl solution,with a platinum plate electrode as the auxiliary electrode and a saturated calomel electrode as the standard electrode.The working electrode was sealed in epoxy resin,with an exposed area of approximately 1 cm×1 cm.The potential scanning range was-1.5 to 1.5 V,and the scanning speed was 4 mV/s.The salt spray test was conducted in a salt spray test chamber,with a NaCl solution with a mass fraction of 5%.The results show that the preferred crystallographic orientation of TiN coating is(111).The orientation of the coating still maintains(111)after N ion implantation.The electrochemical test shows that the equilibrium corrosion potentials all shifts positively for the samples with TiN coating and N ion implantation.The TiN coating shows minimal passive current density.Moreover,the salt spray test shows copper samples with TiN coating or TiN/N ion implantation composite layer can withstand 12 h salt fog corrosion.Therefore,the TiN coating can be used as an optimized method for actual corrosion resistance workpiece with a complex surface shape.