Composition demixing effect on cathodic arc ion plating

The composition demixing effect has been found often in alloy coatings deposited by cathodic arc ion plating using various alloy cathode targets. The characteristics of composition demixing phenomena were summarized. Beginning with the ionization zone near the surface of the cathode target, a physical model in terms of the ions generated in the ionization zone and their movement in the plating room modified by bias electric field was proposed. Based on the concept of electric charge state, the simulation calculation of the composition demixing effect was carried out. The percentage of atoms of an element in coating and from the alloy target was demonstrated by direct comparison. The influences of the composition change of the alloy target and the bias electric field on the composition demixing effect were discussed in detail. It is also proposed that the average charge states of the elements may be used to calculate the composition demixing effect and to design the composition of the alloy target.

Friction and Wear Performances of Cathodic Arc Ion Plated TiAlSiN Coating under Oil Lubricated Condition

TiAlSiN coating was deposited on H13 hot work mould steel using cathodic arc ion plating（CAIP）. The surface-interface morphologies and phases of the obtained coating were analyzed using field emission scanning electron microscopy（FESEM） and X-ray diffraction（XRD）, respectively, and the morphologies, distributions of chemical elements and profiles of worn tracks were also researched using scanning electron microscopy（SEM）, energy disperse spectroscopy（EDS）, and optical microscope（OM）, respectively. The friction-wear performances of TiAlSiN coating under oil lubricated and dry fiction conditions were investigated, and the wear mechanisms of TiAlSiN coating were discussed. The experimental results show that the coating is primarily composed of（Ti, Al）N, AlTiN, and TiN hard phases, Si_3N_4 exists between the（Ti, Al）N crystal grains, increasing the coating microhardness to 3200 HV. The TiAlSiN coating has excellent performances of reducing friction and wear resistance, the average coefficient of friction（COF） of TiAlSiN coating under oil lubricated condition is only 0.05, lowered than the average COF of 0.211 under dry friction condition, the wear rate decreases by about 81.2% compared with that under dry friction condition. The wear mechanism of TiAlSiN coating under oil lubricated and dry friction conditions is composed of abrasive wear, fatigue wear, and abrasive wear, respectively. The internal friction of oil lubrication is a main factor of decreasing fatigue wear.

Structure and wear resistance of TiN and TiAlN coatings on AZ91 alloy deposited by multi-arc ion plating

In order to investigate the microstructure of TiN and TiAlN coatings and their effect on the wear resistance of Mg alloy, TiN and TiAlN coatings were deposited on AZ91 magnesium alloy by multi-arc ion plating technology.TiN and Ti70Al30N coatings were prepared on the substrate,respectively,which exhibited dark golden color and compact microstructure.The microstructures of TiN and Ti70Al30N coatings were investigated by X-ray diffractometry(XRD)and scanning electron microscopy(SEM).The micro-hardness and wear resistance of TiN and Ti70Al30N coatings were investigated in comparison with the uncoated AZ91 alloy. The XRD peaks assigned to TiN and TiAlN phases are found.The hardness of TiN coatings is two times as high as that of AZ91 alloy, and Ti70Al30N coating exhibits the highest hardness.The wear resistance of the hard coatings increases obviously as result of their high hardness.

EXPERIMENTAL STUDY ON SUPERFICIAL COAT OF GEARS OF NITRIDED 32Cr2MoV COATED WITH TiN FILM BY MULTI-ARC ION PLATING

After 32CrMoV is selected to manufacture nitrided gears coated with TiN by multi-arc ion plating, all of these uncoated gears and coated gears run in the gearbox under the same initial conditions so as to compare their difference concerning properties and microstructure. Experiment results indicate that tooth surface of the coated-TiN gears does not suffer surface abnormalities in meshed zone. Instead, the gears with nitrided case exhibit an abrasion mark on the meshed zone of tooth surface, which results in more weight loss of nitrided gears. The morphology of the surface suggests TiN film with more than 2 000 HV is so dense and smooth that coated-TiN gears have higher wear resistance compared with the uncoated gears. The microstructure of coated-TiN gears is finer, hardness is higher and its distribution of coated-TiN gears is more reliable than uncoated ones, which makes nitride layer combined with TiN film tightly. Consequently, the wear-resistance of gears has been dramatically promoted.

Structure and Tribological Properties of CrTiAlN Coatings Deposited by Multi-Arc Ion Plating

CrTiAIN coatings were prepared by using a home-made industrial scale multi-arc ion plating system. The coatings were found to be composites of face-center-cubic CrN and TiN. The surface roughness, microhardness, and tribological properties of the films were significantly affected by the nitrogen pressure and dc-pulsed bias voltage applied to the substrate. The CrTiA1N coatings with the smoothest surfaces were obtained at optimum conditions of nitrogen pressure of 5.0 Pa and bias voltage of -200 V. The samples were found to exhibit a hardness of 2900 HV0.05 with an average friction coefficient of 0.16 and wear rate of 1.5× 10^-16 m^3/N.m against cemented carbide.

Wear-resistance and anti-scuffing of multi-arc ion plating molybdenum films

The multi-arc ion plating technology was employed to prepare the molybdenum films with thickness of 3 μm on the AISI 1045 steel. The wear and scuffing tests were carried out on the ball-on-disc tester. AFM and SEM equipped with EDS were adopted to observe and analyze the morphologies and element compositions of surface,cross-section and worn scar of the Mo film. The phase structure was studied by XRD and the bonding strength between Mo film and substrate was measured by scratching tester. The tribological experiments show that the Mo film possesses a good wear-resistance and an excellent anti-scuffing property. The failure mechanism of Mo film under extreme condition is flaking off.

Copper Ions Removal from Wastewater by Electrocoagulation Using Cement-based Cathode Plates

The present work uses PEO solution to well disperse carbon fiber and identifies percolation thresholds of carbon fiber and carbon black which are used as conductive fillers.The resultant cathode plates have an average compressive strength of 27.3 MPa and flexural strength of 29.09 MPa,which demonstrate excellent mechanical properties.The Cu^(2+)removal efficiency was measured at different current densities in EC process with cement-based cathode plate,while the voltage changes were recorded.The results showed that the cement-based cathode plate operated stably and achieved 99.7%removal of 1 L of simulated wastewater with a Cu^(2+)concentration of 200 ppm at a current density of 8 m A/cm^(2)for 1 h.Characterization of floc and tested cathode plates,SEM and EDS analyses,and repeatability testing of the tested plates demonstrate the reusability of the plates,proving that cement-based plates can effectively replace metal cathode plates,reduce the cost of EC and improve the applicability of EC devices.

STUDIES OF Cr-O THIN FILNS DEPOSITED BY MULTI-ARC ION PLATING

This paper presents the formation of Cr-O thin films on an iron substrate by multi-arc ion plating, which are intended to be used as a thermal radiation absorbent in electronic vacuum devices. Only oxygen was used as a reaction gas during deposition, the Cr-O thin film, must have high adhesion and low outgassing rate. The scratch test shows that the critical load, for an applicable Cr-O thin film deposited in oxygen atmosphere alone at a pressure of 8×10-1 Pa, was as high as 6kg.

Approximate Design of Alloy Composition of Cathode Target

An empirical formula for composition demixing analysis in cathodic arc ion plating using alloy target is established based on the concepts of average charged state and relative demixing parameter. The level of composition demixing effect is presented by demixing degree of one element. For binary constituent alloy target, the composition change trend in coating is discussed and the limit of demixing degree for each element is determined. The content of one element with higher average charged state gets larger in coating than in alloy target, at meantime, the content of one element with lower average charged state gets less. For each one of the two constituents, the less the atom percent in alloy target, the larger the difference of its contents between the coating and the target. For triple constituent alloy target, the content change of one element with moderate average charged state is discussed in detail. Its content in coating getting larger or less is determined by the combination result of the contents of the other two elements in alloy target. For a given content of the element with moderate average charged state in triple alloy target, the content deviation level of that element from coating to alloy target will be not larger than that using binary alloy target containing only that element and one of the two others. According to the wanted coating composition, the composition design of alloy target is easily deduced from the formula.

TiAlN/Cu Nanocomposite Coatings Deposited by Filtered Cathodic Arc Ion Plating

TiAIN]Cu nanocomposite coatings with Cu concentration of 0-1.4 at.% were deposited on the high- speed steel （HSS） substrates by filtered cathodic arc ion plating technique. The chemical composition, microstructure, morphology, adhesion strength, mechanical and tribological properties of the TiAIN/Cu coatings were characterized and analyzed. The results reveal that the coating structure and properties depend on not only the Cu concentration, hut also the deposition condition. The addition of Cu significantly decreases the grain size and weakens the texture in the TiAlN/Cu coatings. With increasing the Cu concentration, the coating hardness decreases slightly from 30.7 GPa of the pure TiAlN coating to 28.5 GPa of the TiAlN/Cu coating with 1.4 at,% Cu. All the TiAlN/Cu coatings present sufficient adhesion strength. In addition, the existing state of additive Cu in the TiAlN/Cu coatings is also investigated.

Thickness Dependence of Structural and Optical Properties of Chromium Thin Films as an Infrared Reflector for Solar-thermal Conversion Applications

The thermal emittance of Cr film, as an IR reflector, was investigated for the use in SSAC. The Cr thin films with different thicknesses were deposited on silicon wafers, optical quartz and stainless steel substrates by cathodic arc ion plating technology as a metallic IR reflector layer in SSAC. The thickness of Cr thin films was optimized to achieve the minimum thermal emittance. The effects of structural, microstructural, optical, surface and cross-sectional morphological properties of Cr thin films were investigated on the emittance. An optimal thickness about 450 nm of the Cr thin film for the lowest total thermal emittance of 0.05 was obtained. The experimental results suggested that the Cr metallic thin film with optimal thickness could be used as an effective infrared reflector for the development of SSAC structure.

High temperature oxidation resistance of CrN/(Ti,Al,Zr,Cr)N bilayer films deposited by multi-arc ion plating

CrN/（Ti,Al,Zr,Cr） N bilayer films were successfully deposited on cemented carbide（ WC-8% Co） substrates by multi-arc ion plating process using two Ti-Al-Zr alloy targets and one pure Cr target. As a result of bilayered structure and addition of alloying elements（ e. g. Al and Cr）,the films exhibited excellent high temperature oxidation resistance under both short-term isothermal（ up to 800 ℃） and long-term cyclic（ up to 600 ℃） exposure conditions. Combined with pre-established outstanding tribological properties（ e. g. maximum hardness of 4 000HV0. 01 and maximum adhesion strength over 200 N）,these observations make such films quite a promising candidate to extend the cutting tool life span and boost the performance in high-productivity,high-speed and high-feed cutting or in dry machining conditions.

Oxidation behavior of TiAlZrCr/(Ti,Al,Zr,Cr)N gradient films deposited by multi-arc ion plating

The two Ti-Al-Zr targets and one pure Cr target were used to prepare the TiAlZrCr/（Ti, Al, Zr, Cr）N gradient films on high speed steel （WlSCr4V） substrates by multi-arc ion plating technique. Short-term isothermal （at 600 ℃, 700 ℃, 800℃ and 900 ℃ for 4 h） and long-terra cyclic （at 700℃ and 800℃ for 100 h） high temperature oxidation behavior of the gradient films were studied. Then the oxide scales formed on the film specimens were characterized by scanning electron microscopy （SEM）, energy dispersion X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. It was showed that, under short-term isothermal condition, the high temperature oxidation resistance of the gradient film was excellent up to 800 ℃ and an oxide scale comprising TiO2 was observed. On the other hand, under long-term cyclic high temDerature condition, the oxidation resistance of the gradient film was excellent at about 700 ℃.

基体材料对TiN薄膜表面液滴及薄膜结合力的影响

采用真空阴极电弧离子镀技术分别在4Cr5MoSiV1(H13)模具钢、Cr18Ni9Ti(304)不锈钢、YG6硬质合金、Ti6Al4V(TC4)钛合金4种基体表面沉积TiN薄膜。利用扫描电镜(SEM)对薄膜表面液滴进行观察分析,通过划痕仪对薄膜的膜/基结合力进行表征。结果表明:基体材料不同,TiN薄膜上液滴的密度、尺寸存在明显的区别。其中,镀膜后H13钢和304不锈钢表面的液滴数量最多,YG6硬质合金次之,TC4钛合金最少;薄膜的膜/基结合强度依次为YG6硬质合金>H13钢>304不锈钢>TC4钛合金。

偏压对阴极电弧离子镀AlN薄膜的影响

在不同基体负偏压作用下，用阴极电弧离子镀等离子体物理气相沉积（ＰＶＤ）方法在单晶 Ｓｔ（１００）基片上获得六方晶系的晶态ＡｌＮ薄膜．用Ｘ射线衍射仪分析了沉积膜的物相组成和晶格位向随 偏压的变化，在扫描电子显微镜（ＳＥＭ）下观察沉积膜的显微组织形貌．结果表明，在较小偏压下，ＡｌＮ 膜呈（００２）择优取向，表面致密均匀；在较大偏压下，ＡｌＮ膜呈（１００）择优取向，表面形貌则粗糙不 平．ＡｌＮ薄膜的择优取向及表面形貌受到不同偏压下不同离子轰击能量的影响．

阴极弧离子镀制备AlCrN涂层的高温摩擦磨损行为

采用阴极离子镀在TiC金属陶瓷刀具表面制备了AlCrN涂层,采用球/平面接触方式考察了900℃高温时不同载荷作下涂层的摩擦磨损行为。通过扫描电镜观察了磨痕轮廓和微观形貌,并用能量散射谱和X射线衍射分析了磨损后涂层表面化学元素和物相的变化,讨论了载荷对涂层摩擦因数和磨损性的影响。结果表明,经900℃高温氧化后,涂层中N元素全部释放,形成Al和Cr的氧化物,改善了润滑性能和磨损性能;在载荷600,800和1000 g作用下,涂层摩擦因数平均值分别为0.1455,0.3939,0.4188,在载荷600 g时表现出优良的摩擦特性,适用于精密切削加工;在高温下AlCrN涂层表现为氧化磨损,同时伴随着少量的磨粒磨损和黏着磨损。

阴极弧离子镀TiAlSiN涂层的微观组织与性能

采用阴极弧离子镀法在GH4169 Ni基合金表面制备TiAlSiN涂层,通过SEM,EDS,XRD和XPS等手段对TiAlSiN涂层表面界面形貌、能谱以及物相结合能谱进行测试分析,并对其结合界面化学元素进行线扫描分析,讨论涂层界面结合机理。研究结果表明:TiAlSiN涂层主要成分为Al,Ti,Si和N元素,化学元素分布均匀,表面没有产生富集现象;涂层具有较强的TiSix和SiNx择优取向化合物,为非晶结构;TiAlSiN涂层是由TiN,AlN和Si3N4等物相组成,Si元素以Si3N4非晶相形式包覆在(Al,Ti)N晶界,细化了涂层晶粒尺寸,其显微硬度达到3 200;涂层在结合界面发生一定的扩散,与基体形成化学结合方式,划痕法测得其结合强度为40.5 N。

纳米晶钛薄膜的制备及结构分析

采用磁控溅射和离子镀膜工艺在Mo基片上制备了具有不同晶粒尺寸的纯Ti薄膜 ,并利用X光衍射 (XRD)、透射电镜 (TEM )和扫描电镜 (SEM )分析和观察了两类Ti膜的结构和形貌。实验结果显示 :与溅射镀膜相比 ,离子镀膜的晶粒择优取向程度略低 ,Ti膜与基片结合较好 ;较高的基片温度有利于提高膜的致密程度 ,并降低膜的晶粒择优取向程序。

磁场模拟在磁控溅射/阴极弧离子镀中的应用

针对磁控溅射和阴极弧离子镀沉积技术存在的局限性,采用有限元分析方法(Finite element method,FEM)进行磁场模拟,优化设计外加电磁线圈的结构和磁场分布位形,并应用于磁控溅射沉积透明导电氧化物和阴极弧离子镀沉积硬质薄膜中。分析了外加电磁线圈磁场对磁控溅射等离子体辉光变化、磁控靶磁场平衡度/非平衡度、以及线圈位置对等离子体特性和靶材利用率的影响。设计和制作了轴对称磁场和旋转磁场,研究了它们对阴极弧离子镀弧斑运动形貌和薄膜表面大颗粒等特性的影响。通过控制弧斑运动状态,可以得到不同程度的颗粒分布,实现颗粒的可控沉积,减少薄膜表面大颗粒的污染。

AZ91C镁合金表面Ti-TiN复合镀层的阴极多弧离子镀法制备与表征

采用阴极多弧离子镀膜技术,在AZ91C镁合金基底上首次成功镀制了结合力强的以Ti为过渡层的TiN复合膜层,并利用高分辨扫描电子显微镜(SEM)、X射线能谱仪(EDS)、显微划痕测试等技术对复合膜层的形貌、组织结构及性能进行分析研究。结果表明,采用多弧离子镀膜工艺,能在经过恰当预处理的镁合金基底上制备出性能良好的TiN膜,膜层均匀、致密,膜基结合力达130 mN以上,复合硬度达500 HV左右(AZ91镁合金基底为125 HV)。此外中性盐雾强化实验表明,经该方法处理后的镁合金在ASTM-B117标准测试条件下,腐蚀速率明显降低,经过200 h后,表面无明显腐蚀现象。真空多弧离子镀膜技术有望在镁合金表面防护领域得到应用。