过滤式阴极电弧沉积类金刚石薄膜工艺的研究

本文研究了过滤式阴极电弧沉积系统的稳弧工艺参数,通过正交试验获得最佳稳弧参数,并且研究了弯管内置挡板对宏观粒子过滤效果的影响,采用喇曼光谱研究了偏压对生成的类金刚石薄膜性能的影响,证明－１００Ｖ偏压下,获得的类金刚石薄膜有最佳的ｓｐ＾３含量,扫描电镜测试表明,在（１１１）硅基片上获得致密的膜,但在高速钢基体上沉膜堆积现象比较严重,不易获得优质类金刚石膜。     

磁过滤直流真空阴极弧制备类金刚石膜的结构及其性能

采用磁过滤直流真空阴极弧沉积技术在单晶硅片、载玻片、不锈钢片基体上制备了类金刚石(DLC)膜.用光学显微镜、椭偏仪、Raman光谱、X射线光电子能谱(XPS)、X射线衍射能谱(XRD)、纳米硬度计、摩擦磨损仪、洛氏硬度计检测了薄膜的组分、结构、光学、力学等相关特性.结果表明,膜中均存在着微米级的大颗粒分布.硅片上的薄膜厚度均为37 nm左右,75 V、100 V偏压下制得的薄膜具有最高的sp3键含量,薄膜具有典型的DLC膜Raman光谱特征.玻片上的DLC膜具有良好的红外透射性能.不锈钢片上的薄膜为非晶碳结构,硬度受膜厚的影响显著,在空气中的摩擦因数均约为0.1左右,耐磨性能优良,随着膜厚的增加,膜与基体的结合性能变差.采用Cr/Cr-DLC膜(含铬DLC膜)作为不锈钢的梯度过渡层时可以极大地提高膜基间的结合性能.     

膜厚对四面体非晶碳薄膜机械性能和拉曼表征的影响

采用过滤阴极真空电弧技术以相同的工艺条件在单晶硅衬底上制备了不同厚度的四面体非晶碳薄膜.利用表面轮廓仪测试薄膜的厚度和应力,利用纳米压入仪测试薄膜的硬度、弹性模量和临界刮擦载荷,利用可见光拉曼光谱表征薄膜的结构.试验结果表明:随着膜厚的增加,薄膜的应力持续降低,当膜厚超过30 nm时,应力低于5 GPa;当膜厚超过300nm时,硬度和弹性模量分别接近70 GPa和750 GPa,十分接近体金刚石的性能指标;随着膜厚的增加,可见光拉曼光谱中衬底硅的一阶和二阶谱峰强度逐渐降低,但非晶碳一阶谱峰的最大峰强、峰位和半高宽有特定的变化规律;峰位逐渐向低频偏移,在50～80 nm膜厚范围,半高宽最窄,峰强最高.     

过滤式阴极电弧沉积类金刚石薄膜的性能分析

成功地研制了一套过滤式阴极电弧沉积设备,并利用该设备成功获得了类金刚石薄膜。类金刚石薄膜的扫描电镜分析表明：获得的薄膜在硅基片上是光滑和致密的,在Ｔｉ合金基片上有裂纹,高速钢基片上有微孔。原子力显微镜分析表明：膜层的表面粗糙度与沉积参数密切相关。喇曼光谱研究表明,这种薄膜是典型的无氢类金刚石薄膜,喇曼光谱的高斯分解表明：随着偏压的变化,Ｄ线和Ｇ线的位置μＤ、μＧ向低频移动,半高宽σＤ减小。     

工艺参数对空心阴极真空电弧电子温度影响

为了研究空心阴极真空电弧等离子体特性,通过光谱仪获得了空心阴极真空电弧的发射光谱分布,同时利用相对强度法计算了电子激发温度.结果表明,空心阴极真空电弧等离子体主要由氩离子、氩原子构成;随着放电气压的降低和焊接电流的增加,空心阴极真空电弧的离子浓度逐渐增加;在一定气体流量下,空心阴极真空电弧的电子激发温度随着焊接电流的增加而升高;在低气体流量、大焊接电流时,电子激发温度较高;随着放电气压的升高,空心阴极真空电弧的电子激发温度逐渐降低.当焊接电流较大和气体流量较低时,空心阴极真空电弧的轴线附近的氩离子谱线强度较高,并且其径向分布梯度较大.     

电极材料组织对真空电弧阴极斑点运动行为的影响

真空电弧在非晶、纳米晶及常规粗品电极合金表面微观分布的观测表明,电极材料显微组织对电弧阴极斑点几何性质和运动行为有明显影响．阴极斑点优先在材料承载电压能力低的弱相表面形成,弱相尺寸、形貌和分布决定了阴极斑点的几何特征．显微组织大幅度细化时,电弧在电极表面分散和快速运动,非晶合金表面仍保持完全非晶结构．分析表明,当材料特征显微组织尺寸小于阴极斑点尺寸时,阴极斑点运动模式从跳跃式运动转变为连续式运动．电极材料组成相的浓度及其尺寸是决定阴极斑点微观迁移方式的重要因素．     

空心阴极真空电弧焊接的引弧机理

空心阴极真空电弧焊接（Hollow Cathode Vacuum Arc Welding,HCVAW)技术是一项新型、独特的技术,在航空,航天等工业部门有着巨大的应用潜力,本文介绍了空心阴极真空电弧焊接技术的特点及其放电机理,讨论了低气压下空心阴极电弧放电与常规电弧和电的不同特点,根据电离气体中性化条件,初步探讨了在低气压下空心阴极电弧放电的引弧过程,分析了影响低气压下空心阴极电弧放电引弧电压的因素。     

Structure and properties of cathodic vacuum arc deposited NbN and NbN-based multi-component and multi-layer coatings

Binary Nb-N coatings, ternary Ti-Nb-N and Zr-Nb-N, and multi-layer TiN/NbN coatings consisting of up to 100 alternating TiN and NbN layers, were deposited onto WC-Co substrates, using two different vacuum arc deposition (VAD) systems: with and without magnetic guiding of the metal plasma flow. Binary Nb-N coatings were fabricated by deposition of metal plasma produced by a Nb cathode in a background of reactive nitrogen gas at different pressures, P. Ternary coatings were fabricated at co-deposition of plasmas originating from two different cathode materials. Multilayer coatings were fabricated by alternatively depositing plasmas of Ti and Nb in reactive nitrogen gas. The crystalline coating structure, phase composition, hardness and critical load for coating failure were studied.For binary Nb-N coatings fabricated using both deposition systems, the phase composition, the Vickers hardness, HV, and the critical load strongly depended on the deposition pressure. Using VAD with magnetic plasma guiding, the highest HV of ∼ 42 GPa was measured for coatings deposited at low nitrogen pressure. These coatings contained a hexagonal β-Nb₂N phase and had a relatively low critical load. The highest critical load and HV ∼ 38 GPa were obtained for coatings consisted of a single phase NaCl-type cubic δ-NbN structure, deposited at a higher nitrogen pressure. The structure and properties of Nb-N coatings deposited using VAD without magnetic plasma guiding had a similar correlation with the deposition pressure, however, their hardness values were lower.Ternary Ti-Nb-N and Zr-Nb-N coatings fabricated by both deposition processes had a single phase cubic NaCl-type structure and the hardness higher than that of the binary nitrides TiN, ZrN and NbN. The hardest coatings, HV ∼ 51.5 Pa, deposited with magnetic plasma guiding had a single-phase cubic δ-(Ti,Nb)N structure and a Ti:Nb ratio of ∼ 50:50 (at.%).Multilayer coatings TiN/NbN consisting of 20-40 alternating TiN and NbN layers with total thickness of 4-5 μm increased the life time of cemented carbide cutting inserts at turning tough Ni-base alloys by 2-7 times relative to uncoated cutting tools, while conventional vacuum arc deposited TiN coatings were not effective in machining of these alloys.     

磁过滤等离子体制备TiN薄膜中沉积条件对薄膜织构的影响

在室温条件下,利用自行设计的平面"S"形磁过滤等离子体设备,在(111)面单晶硅上制备TiN薄膜,通过改变基底偏压和反应气体成分,即通过改变氮气和氩气的气体流量来改变沉积离子的能量和密度,从离子轰击的角度研究了沉积条件对TiN薄膜织构的影响.对薄膜的表面形貌进行观察,用(θ～2θ)和1.5°掠入射2种X射线衍射方法对薄膜晶体结构和晶面取向进行了分析,对薄膜进行了电子衍射研究.结果显示磁过滤等离子制备的TiN薄膜表面平整光滑,颗粒尺寸为20～70 nm,且基底偏压和氩气流量的增大促使薄膜发生(111)面的择优取向,且(111)晶面与膜表面平行,而在高氩气流量的情况下,(200)和(220)面在薄膜平面也发生了定向排列.     

Antibacterial activity of silver surface modified polyethylene terephthalate by filtered cathodic vacuum arc method

Silver (Ag) modified polyethylene terephthalate (PET) surface by filtered cathodic vacuum arc (FCVA) technique is performed. The structure and component of the modified surface are characterized by X-ray photoelectron spectroscopy (XPS) and the cross-section is observed by scanning electron microscope (SEM). The results show that a 4-5 μm silver layer is formed on the PET surface. The results of the colony forming units (CFU) plate counting in vitro indicate that the adhesion of Staphylococcus epidermidis (SE) to PET is suppressed by silver coating. The adhesion efficiency of SE on the modified surface is only about 25% of the untreated PET surface. The interfacial free energy of adhesion (ΔF_Adh) of SE onto the silver coating deposited on PET is + 8.6 mJ/m², and this means that bacterial adhesion is energetically unfavorable. The releasing rate of silver ions from the PET modified by silver FCVA is 0.12 μg/mL during 2 h. The release of antibacterial silver ion may be another reason of less SE adhered to the PET surface modified by Ag FCVA. The release of lactate dehydrogenase (LDH) was used to evaluate the immediate toxicity of the PET modified by silver FCVA method. It is showed that this modified surface has low toxicity.     

Microstructure and mechanical properties of TiN/AlN multilayers deposited by filtered vacuum arc deposition

Nanometer TiN/AlN multilayers were prepared on silicon substrate by filtered vacuum arc deposition.The structures of the nanometer TiN/AlN multilayer were studied by using X-ray diffraction. The 12 nm TiN/AlN multiplayer is composed of cubic TiN structure and hexagonal wurzite AlN structure, but the 2 nm period multilayer is composed of face centered cubic structure TiN and AlN with strong (200) texture. The surface roughness, hardness and elastic modulus of multilayer are dependent on the period of multilayer. The hardness of the TiN/AlN multilayers is higher than that suggested by a simple rule of mixture. The peaking hardness of nanometer TiN/AlN multilayers at period of 2 nm is about 42 GPa, much higher than that of 12 nm. The wear resistance of the nanometer TiN/AlN multilayers was also studied.     

Copper film deposition rates by a hot refractory anode vacuum arc and magnetically filtered vacuum arc

Two vacuum arc deposition techniques were compared for metal film deposition: 1) filtered vacuum arc deposition (FVAD), which applies a magnetic field to separate the plasma from macroparticles (MPs) generated in the cathode spots, and 2) hot refractory anode vacuum arc (HRAVA) deposition, in which anode plasma plume forms by re-evaporation of cathode material from the hot anode surface and MPs are vaporized in the hot interelectrode plasma. A Cu cathode and an arc current of 200 A were used in both systems.The FVAD film thickness was axially symmetric to within 10-20%. The focused plasma jet in the FVAD system covered a circular area, where the radius for half-thickness is ∼ 30 mm. The deposition rate was constant in time and maximal (about 0.25 μm/min) in the center of the circular area. The mass deposition rate was about 9.5 mg/min assuming bulk density.The HRAVA deposition rate initially increased with time and saturated at a maximum of ∼ 2.3 μm/min after 1 min. The plasma expanded radially, and was deposited on a cylindrical area of 100 cm² and height ∼ 20 mm, which was co-axial with the electrode axis. The thickness distribution was axially symmetric within 10%. The steady-state mass deposition rate was 400 mg/min. The HRAVA system produced an almost MP-free radially expanded mass throughput and cathode utilization efficiency ∼ 40 times greater than with the FVAD system.     

Amorphous coatings deposited on aluminum alloy by plasma electrolytic oxidation

Amorphous [Al-Si-O] coatings were deposited on aluminum alloy by plasma electrolytic oxidation (PEO). The process parameters, composition, micrograph, and mechanical property of PEO amorphous coatings were investigated. It is found that the growth rate of PEO coatings reaches 4.44μm/min if the current density is 0.9 mA/mm^2. XRD results show that the PEO coatings are amorphous in the current density range of 0.3 - 0.9 mA/mm^2. EDS results show that the coatings are composed of O, Si and A1 elements. SEM results show that the coatings are porous. Nano indentation results show that the hardness of the coatings is about 3 - 4 times of that of the substrate, while the elastic modulus is about the same with the substrate. Furthermore, a formation mechanism of amorphous PEO coatings was proposed.     

Mechanical and tribological properties evaluation of cathodic arc deposited CrN/ZrN multilayer coatings

Five nanostructured CrN/ZrN multilayer coatings were deposited periodically by cathodic arc evaporation. The bilayer periods of the CrN/ZrN multilayer coatings were controlled in the range of 5 to 30 nm. The structures and bilayer period of the multilayer coatings were characterized by an X-ray diffractometer. The microstructures of thin films were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. Nanoindentation, scratch tests, Daimler–Benz Rockwell-C (HRC-DB) adhesion tests, microhardness and pin-on-disk wear tests were used to evaluate the hardness, adhesion, indentation toughness and tribological properties of thin films, respectively. It was found that the hardness and tribological properties were strongly influenced by the bilayer period of the CrN/ZrN multilayer coatings. An optimal combination of mechanical properties and excellent tribological behavior was found for a coating with a critical bilayer period of 30 nm.     

Hall stratum filtered cathodic arc source for carbon plasma

A novel filtered cathodic vacuum arc source of carbon plasma, in which plasma ions are reflected from a Hall stratum formed in the inter-electrode gap, was studied. The plasma source consisted of a rectangular carbon cathode, positioned between the poles of a permanent magnet, a copper anode, and a triggering mechanism. An arc was operated with current pulses having a duration of 7 ms and a peak current of 200 A.It was shown that the cathode spot plasma jets were reflected from the Hall stratum formed in the arched magnetic field, and bent through 180° towards substrates positioned alongside of the cathode, while macroparticles flew from the cathode spots in straight trajectories. The calculated thickness of the Hall stratum ranged from less than 1 mm to ≥ 10 mm. The ratio of the substrate ion current to the arc current was ∼ 7.5%, which is much larger than that of most known filtered systems, and approaches the plasma transfer efficiency of unfiltered vacuum arc plasma sources.     

High temperature tribological characterisation of TiAlSiN coatings produced by cathodic arc evaporation

This study reports on the wear properties at medium-high temperatures of TiAlSiN films deposited by cathodic arc evaporation on hot work steel substrates. The chemical composition and microstructure of the coatings were characterised by glow discharge optical emission spectroscopy, scanning electron microscopy and X-ray diffraction. The mechanical properties, i.e. hardness and elastic modulus were evaluated by nanoindentation, and the adhesion of the coatings was tested by scratch tests. Coatings with stoichiometries of Ti_0.31Al_0.1Si_0.06N_0.53 and Ti_0.23Al_0.12Si_0.09N_0.55 exhibit microstructures consisting of solid solutions of (Ti,Al,Si)N, where Al and Si replace Ti atoms. These films show high hardness and good adhesion strength to the hot work steels. Conversely, coatings with a stoichiometry of Ti_0.09Al_0.34Si_0.02N_0.55 show a wurtzite-like microstructure, low hardness and poor adhesion strength.The wear rates of the coatings were investigated by ball-on-disc experiments at room temperature, 200 °C, 400 °C and 600 °C, using alumina balls as counter surfaces. At room temperature, the films show wear rates of the same order of magnitude of TiN and TiAlN coatings. On the other hand, the wear rates of solid solution (Ti,Al,Si)N coatings measured at 200, and 400 °C are one order of magnitude smaller than those measured at room temperature due to the formation of oxide-containing tribofilms on the wear tracks. At 600 °C the wear rates increase but still keep smaller than those measured at room temperature, although this effect can be influenced by the softening of the steel substrates by over-tempering. EDS analyses revealed that, between 200 °C and 400 °C, the oxidation of the coating occurs only at the contact zone between the film and the counterpart body due to the sliding process.     

Properties of TiAlCrN coatings prepared by vacuum cathodic arc ion plating

TiAlCrN coatings were deposited by means of vacuum cathodic arc ion plating technique on TC11 (Ti-6.5 Al-3.5 Mo-1.5 Zr-0.3Si) titanium alloy substrates. The composition, phase structure, mechanical performance, and oxidation-resistance of the nitride coatings were investigated by scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), auger electron spectroscopy (AES), and X-ray photoelectron microscopy (XPS). A new process for preparing protective coatings of the titanium alloy is successfully acquired. The experimental results indicate that the added element chromium in the TiAlN coatings make a contribution to form the (220) preferred direction. The phases of the coatings are composed of (Ti, Al)N and (Ti, Cr)N. After 700℃ and 800℃ oxidation, AES analysis shows that the diffusion distribution of the TiAlCrN coatings emerges a step shape. From the outside to the inner, the concentrations of O, Al, and Cr reduce, but those of Ti and N increase. The Al-rich oxide is formed on the surface of the coatings, and the mixed structure of Ti-rich and Cr-rich oxides is formed in the internal layer. The oxidation resistance of the TiAlCrN coatings is excellent at the range of 700 to 800℃. Adhesion wear is the dominant mechanical characteristic for the titanium alloy at room temperature, and the protective coatings with high hardness can improve the mechanical properties of the titanium alloy. The wear resistance of the TC11 alloy is considerably improved by the TiAlCrN coatings.