元素扩散对Cr_(2)O_(3)陶瓷薄膜结构和摩擦学性能的影响

Effect of Element Diffusion on Structure and Tribological Properties of Cr_(2)O_(3) Ceramic Films Prepared by Multi-arc Ion Plating

目的通过高温热处理,不同基材会发生不同的组织演变,研究了组织演变对基材中金属元素高温扩散的影响,从而判断其对多弧离子镀制备Cr_(2)O_(3) 陶瓷薄膜形貌、结构以及摩擦学性能的影响。方法利用多弧离子镀技术在不同基材表面(Inconel 718合金、IC10合金、45钢、316不锈钢)沉积Cr_(2)O_(3) 薄膜。使用扫描电子显微镜(SEM)和冷场发射扫描电镜(FESEM)分析了基材和薄膜高温退火前后的表面形貌,并且利用EDS分析了基材和薄膜表面的元素含量变化。采用X射线衍射仪(XRD)对Cr_(2)O_(3) 薄膜进行物相分析,使用往复摩擦磨损试验仪、三维轮廓仪以及扫描电子显微镜分析了基材和薄膜退火前后的摩擦学性能。结果热处理后基材中的元素会扩散到其表面,Inconel 718合金、IC10合金和45钢热处理后,其摩擦因数降低。在Inconel 718合金和316不锈钢表面沉积的Cr_(2)O_(3) 薄膜高温退火后,基材中的金属元素沿着Cr_(2)O_(3) 薄膜晶界扩散至薄膜表面,并与大气中的O_(2)反应形成三元氧化物。Cr_(2)O_(3) 薄膜经1000℃退火后,Inconel 718合金中的Ti元素扩散至Cr_(2)O_(3) 薄膜表面形成类网状凸起结构,且薄膜表面形成CrTiO_(3)和Cr_(2)O_(3) 混合相,316不锈钢中的Mn元素扩散至Cr_(2)O_(3) 薄膜表面形成尖晶石结构的MnCr_(2)O_(4)相,45钢表面上沉积的Cr_(2)O_(3) 薄膜在850℃退火后薄膜表面形成以Fe元素为主的大颗粒,薄膜表面物相为Fe_(2)O_(3)和Cr_(2)O_(3) 混合相,IC10合金表面上沉积的Cr_(2)O_(3) 薄膜表面没有发现基材中的金属元素,主要物相为Cr_(2)O_(3) 相。Cr_(2)O_(3) 薄膜退火后摩擦因数降低至0.45左右。结论Inconel 718合金、45钢以及316不锈钢中的金属元素扩散至薄膜表面时,其对Cr_(2)O_(3) 薄膜的物相组成、表面形貌以及摩擦学性能有很大的影响。IC10合金表面上沉积的Cr_(2)O_(3) 薄膜热处理后,磨损寿命较低。Inconel 718合金表面上沉积的Cr_(2)O_(3) 薄膜具有优异的摩擦学性能。

The Cr_(2)O_(3) ceramic films prepared by multi-arc ion plating possess a low friction coefficient,good wear resistant and oxidation resistance.Meanwhile,high temperature annealing could improve the mechanical properties of Cr_(2)O_(3) films significantly.In previous work,we found that the metal elements in the substrate would diffuse to the film surface and oxidize to form a ternary metal oxide with lubricating property.Thus,in order to research the diffusion behaviours of the metal elements in the substrate,the effects of microstructure evolution of the substrates on the metal elements diffusion in high temperature,and the evolutions of morphologies,microstructure and tribological properties of the Cr_(2)O_(3) films were also researched in detail.Cr_(2)O_(3) ceramic films were deposited on the surfaces of different substrate(Inconel 718 alloy,IC10 alloy,45 steel and 316 stainless steel,polished to a roughness(Ra)of 20 to 40 nm)by multi-arc ion plating technology.Pure Ar(99.99%)and O_(2)(99.99%)were utilized as working gases.After cleaning with acetone for three times and drying with nitrogen,the substrates were pre-heated to 150℃by placed into the vacuum chamber.Substrates were cleaned with Ar+(bias voltage‒800 V,pressure 2.1 Pa,25 min)to remove oxides layer on the surface of the substrates.Firstly,Cr transition layer was deposited to improve adhesion strength between substrate and Cr_(2)O_(3) film in pure Ar atmosphere,and then O_(2) was slowly introduced within 5 minutes,finally Cr_(2)O_(3) film was deposited for 30 minutes.The working current,voltage,duty cycle,substrate temperature,working pressure and ratio of O_(2):Ar were 80 A,‒100 V,40%,150℃,0.63 Pa,110:200(mL/min),respectively.The films deposited on the surface of Inconel 718 alloy,IC10 alloy and 316 stainless steel were annealed at 1000℃,and the film deposited on the surface of 45 steel was annealed at 850℃.Meanwhile,the corresponding different substrates were also annealed accordingly.Scanning electron microscope(SEM)and cold field emission scanning electron microscope(FESEM)are used to analyze the surface morphologies of the substrate and film before and after annealing and the changes of element content on the surface of the substrate and the film are analyzed by EDS.The phase of Cr_(2)O_(3) films are analyzed by X-ray diffraction(XRD).The tribological properties of the substrate and film before and after annealing are analyzed by reciprocating friction and wear tester,a three-dimensional profiler and SEM.After annealing,the elements in the substrate diffuse to its surface,and the friction coefficient of Inconel 718 alloy,IC10 alloy and 45 steel are reduce.The metal elements in the substrate of Inconel 718 alloy and 316 stainless steel diffuse along the grain boundary of the Cr_(2)O_(3) film to the surface in the process of annealing,and then form the ternary oxides in atmosphere.After annealing at 1000℃,the Ti element in Inconel 718 alloy diffuse to the surface of the Cr_(2)O_(3) film and form a mesh-like heave structure which comprised of CrTiO_(3) and Cr2O3.The Mn element in 316 stainless steel diffuse to the surface of the Cr_(2)O_(3) film and form spinel structure of MnCr_(2)O_(4) phase.After annealing at 850℃,the Cr_(2)O_(3) film deposited on surface of 45 steel forms large particles dominated by Fe elemen.The phase of the film surface is a mixed phase of Fe_(2)O_(3) and Cr2O3.Metal elements in the substrate are not found on the surface of the Cr_(2)O_(3) film deposited on the IC10 alloy,and the main phase is Cr_(2)O_(3).The friction coefficient of the Cr_(2)O_(3) film reduces to about 0.45 after annealing.Metal elements in Inconel 718 alloy,45 steel and 316 stainless steel diffuse to the surface of the film,which has a great influence on the phase composition,surface morphologies and tribological properties of the Cr_(2)O_(3) film.The Cr_(2)O_(3) film deposited on the surface of the IC10 alloy has a poor anti-wear performance after annealing.The Cr_(2)O_(3) film deposited on the surface of Inconel 718 alloy exhibits excellent tribological properties.