Bonding strength of DLC film on zirconia coating prepared by gas tunnel type plasma spraying

Bonding strength of diamond-like carbon (DLC) films on zirconia coatings prepared using a novel gas tunnel plasma spraying method has been studied and discussed. The emphasis is on the getting better characteristics of such doubly structured coatings (DSC) as comparing compared with properties of both components involved in the coatings. For the study of various failure mechanisms zirconia coatings of different thicknesses on aluminum substrates were prepared. The as-sprayed coatings were firstly polished and then subjected to deposition of DLC films. Adhesion of the DSC has been evaluated using a scratch test method. It has been found that the thicker coatings have higher hardness and lower porosity. The adhesion failures of DLC films on zirconia coatings (DSC) are caused by two different main mechanisms: (i) DLC films separation from the zirconia coatings, and (ii) DLC films breaking under stress load due to the brittleness of the material. In addition the adhesion failures are due to flaking of DLC films on the thinner zirconia coatings caused by a distortion of the aluminum alloy substrate coatings; and, chipping of DLC films themselves on the thicker zirconia coatings.     

射频辉光放电等离子体辅助化学气相沉积法制备类金刚石碳膜工艺与性能表征

使用射频辉光放电等离子体辅助化学气相沉积技术（简称RFGDPECVD）在玻璃载玻片表面沉积类金刚石薄膜。用原子力显微镜（AFM）、摩擦试验仪、划痕试验机测定了其表面形貌、耐磨性及附着性。采用X射线光电子能谱（XPS）、分光光度计对两种气源（C4H10、C2H2）制备的DLC薄膜微观组成和透光率进行了检测和对比。结果表明：DLC薄膜的表面光滑、平整,表面粗糙度随沉积时间的增加单调递增;耐磨性及附着性优良;与C4H10相比使用C2H2作为碳源气体可以得到较高Sp^3含量和较低Sp^1含量的DLC膜;C2H2制备DLC薄膜的透光率低于C4H10;同一种碳源气体,反应流量比例越小,则DLC薄膜的透光性越好。     

类金刚石薄膜的紫外可见区光学特性研究

在类金刚石薄膜（DLC）光学特性的研究方面,主要工作集中在红外区光学特性,在可见区和紫外区光学特性研究方面存在空白;鉴于此详细研究了采用脉冲电弧沉积DLC薄膜在可见区和紫外区的光学特性。利用脉冲电弧离子镀技术,在石英基片上和不同工艺条件下制备了类金刚石薄膜,研究了类金刚石薄膜在紫外和可见区的光学常数、光学透过率和光学能隙。结果表明,主回路电压是薄膜的光学常数变化的主要影响因素,低主回路电压下制备的类金刚石薄膜具有较低消光系数和折射率;不同的工艺条件下制备的类金刚石折射率从2．56变化到1．89（波长400nm）;沉积速率对薄膜的折射率和消光系数没有明显的影响;DLC薄膜的光学能隙在3．95eV左右;紫外区和可见区的透过率谱和椭偏仪测得的光学常数相互一致。     

Analysis of diamond-like carbon and Ti/MoS2 coatings on Ti–6Al–4V substrates for applicability to turbine engine applications

Ti–6Al–4V substrates have been coated by diamond-like carbon (DLC) films, with no surface pretreatment, and have been coated by Ti/MoS₂ films, with a simple surface pre-cleaning. The DLC films were deposited by planar coil r.f. inductively-coupled plasma-enhanced chemical vapor deposition (r.f. ICPECVD); the Ti/MoS₂ films were deposited by magnetron sputtering. Both the DLC and Ti/MoS₂ films were characterized by pull tests, hardness tests, scanning electron microscopy (SEM), and wear tests (pin-on-disk and block-on-ring) to compare their adhesion, hardness, surface topology, and wear properties to plasma-sprayed Cu–Ni–In coating currently used for turbine engine applications. The DLC films were easily characterized by their optical properties because they were highly transparent. We used variable-angle spectroscopic ellipsometry (VASE) to characterize thickness and to unequivocally extract real and complex index of refraction, providing a rapid assessment of film quality. Thicker coatings yielded the largest hardness values. The DLC coatings did not require abrasive pretreatment or the formation of bond-layers to ensure good adhesion to the substrate. Simple surface pre-cleaning was also adequate to form well-adhered Ti/MoS₂ on Ti–6Al–4V. The results show that the DLC and Ti/MoS₂ coatings are both much better fretting- and wear-resistant coatings than plasma-sprayed Cu–Ni–In. Both show excellent adhesion to the substrates, less surface roughness, harder surfaces, and more wear resistance than the Cu–Ni–In films.     

弧电流对电弧离子镀沉积超硬ta-C薄膜的影响

用电弧离子镀设备,以获得超硬四面体非晶ta-C薄膜为目的,通过改变弧电流,在硬质合金基体上沉积制备了5组类金刚石DLC薄膜,主要考察弧电流对薄膜结构、性能以及获得超硬ta-C薄膜的影响规律。采用SEM、Raman、XPS、纳米压痕以及摩擦磨损仪分别表征了薄膜的形貌、结构、力学性能以及摩擦性能。结果表明：当弧电流为30 A时,薄膜表面最为平整致密、大颗粒数量最少,Raman谱的I_D/I_G值最小为0.87、sp^₃键含量最大为64%,薄膜的硬度和弹性模量最大分别为56.7 GPa和721.1 GPa、弹性恢复系数高达58.9%,且薄膜的摩擦系数最小为0.073,表明此时获得了具有优异综合性能的超硬ta-C薄膜;但随着弧电流的增加,薄膜表面变得疏松多孔、表面大颗粒增多,I_D/I_G增大、sp^₃键含量减小,薄膜的硬度H和弹性模量E逐渐减小,薄膜的摩擦系数也逐渐增大、摩擦性能大大降低,此时薄膜又归于呈现普通的性能一般的DLC薄膜特征。分析表明,若用电弧离子镀技术制备性能优异的超硬四面体非晶ta-C薄膜,需控制薄膜在较小的离子通量下沉积生长,为此需选择较小的弧电流方能实现。     

Modification of diamond-like carbon coatings with fluorine to reduce biofouling adhesion

Diamond-like carbon (DLC) and fluorinated DLC (F-DLC) coatings were deposited onto 10 mm stainless steel 316 L discs by radio frequency plasma-enhanced chemical vapour deposition (rf PECVD). Surface energy analysis of the F-DLC coatings revealed that with increasing F content the total surface energy decreased significantly, which was attributed to the change of the bonding nature in the coatings, in particularly increasing CF and CF₂ bonds. The anti-biofouling property of F-DLC coatings was evaluated with Pseudomonas fluorescens, which is one of the most common bacteria forming biofilms on the surface of heat exchangers in cooling water systems. The experimental results showed that the incorporation of fluorine into the DLC coatings reduced bacterial attachment and increased bacterial removal. The F-DLC coatings with higher F content (39.2 at.%) reduced bacterial attachment by 48.8% and increased removal by 90.2%, compared with a standard DLC coating.     

Hydrogen content variation for enhancing the lubricated tribological performance of DLC coatings with ester

There are many types of DLC (diamond-like carbon) coatings, which mainly differ from each other according to their hydrogen content, sp² and sp³-bonded carbon atoms and alloying elements (such as Ti, Cr, W or Zr). The lubricated tribological performance of these coatings depends on the lubricant. Controversially, the same lubricant delivers different tribological performances with differently produced DLC coatings. It has been observed that the presence of hydrogen has a remarkable effect on the tribological performance of DLC coatings in inert and vacuum environments. In this paper, the hydrogen content of two different types of DLC coatings, a-C:H:Me (metal containing hydrogenated amorphous carbon) and a-C:H, was varied, in order to obtain an optimized tribological behavior with a synthetic ester (TMP ester). The tribological performance of the coatings with TMP ester is examined in a pin-on-disk tribometer. It could be shown that increasing the hydrogen content in a DLC coating improves their tribological performance with TMP ester. Besides, a-C:H type of coatings is found to be more suitable for TMP ester regarding low friction coefficients.     

A novel technique to enhance surface properties of DLC films deposited on the inner wall of cylindrical PET barrel by DC-RF hybrid discharge

A newly proposed technique has been utilized to improve surface properties of gas barriering DLC films deposited on PET bottle. The discharge in the bottle is induced by radio-frequency discharge and an external DC system is coupled to the RF power supply to control the potential of discharge electrode. In contrast to conventional discharge configuration, this leads to the capability to optimize the ion bombardment energy and surface properties of deposited films. The effect of negative DC voltage on the adhesion strength, optical transmittance, surface profile, roughness, and permeability of DLC coated PET samples has been investigated using immersion test, UV-visible spectroscopy, optical profilometry, and gas permeability tester, respectively. The results have demonstrated that the DLC coated PET samples with external bias show slight damage during beer immersion tests. Lower light transmittance is induced for the films deposited at high negative bias due to larger ion bombardment effect. There exists a proper bias to give rise to a small surface roughness. The gas permeability of DLC coated PET samples deposited with external bias has been substantially decreased compared to that of untreated one.     

Effect of metal ion implantation on thermal instability of diamond-like carbon films

In this work, molybdenum and tungsten ions were implanted onto the DLC films deposited by filtered cathodic vacuum arc. We investigated the effects of ion species and doses on carbon related bonding property such as the ratio of sp³ carbon to sp² phase, the chemical composition and tribological properties of the DLC films in the range of 200 to 600 °C. The oxidation starting temperature decreased with an increasing ion dose and ion mass owing to higher sp² carbon fraction. Oxidation of the implanted-metal element, however, keeps the DLC film from carbon sublimation by oxidation, offering stable tribological characteristics by covering it with a metal oxide layer at the high temperature.     

STRUCTURE, MECHANICAL PROPERTIES AND THERMAL STABILITY OF DIAMOND-LIKE CARBON FILMS PREPARED BY ARC ION PLATING

Diamond-like Carbon (DLC) films have been prepared on Si(lO0) substrates by arc ion plating in conjunction with pulse bias voltage under He atmosphere. The deposited films have been characterized by scanning electron microscopy and atomic force microscopy. The results show that the surface of the film is smooth and dense without any cracks, and the surface roughness is low. The bonding characteristic of the films has been studied by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. It shows the sp^3 bond content of the film deposited at -200V is 26. 7%. The hardness and elastic modulus of the film determined by nanoindentation technique are 30.8 and 250.1GPa, respectively. The tribological characteristic of the films reveals that they have low friction coefficient and good wear-resistance. After deposition, the films have been annealed in the range of 350-700℃ for 1h in vacuum to investigate the thermal stability. Raman spectra indicate that the ID/IG ratio and G peak position have few detectable changes below 500℃. Further increasing the annealing temperature, the hydrogen can be released, the structure rearranges, and the phase transition of sp^3 configured carbon to sp^2 configured carbon appears.     

铝合金表面沉积类金刚石薄膜的研究进展

类金刚石(Diamond-like Carbon,DLC)薄膜因其高硬度、良好的化学惰性以及优异的摩擦性能等优势,有望成为一种理想的铝合金表面防护涂层。对比了物理气相沉积(Physical vapor deposition,PVD)技术制备DLC改性材料与传统铝合金表面改性技术的优劣,概述了DLC薄膜在提升铝合金表面力学性能、减摩抗磨方面取得的最新成果,以及在复杂服役工况下面临的抗塑性变形差、易发生结合失效等瓶颈性问题。通过分析铝合金基体上生长高性能DLC薄膜的不利因素,指出界面化学结合强度低、薄膜残余应力大以及软基体/硬质薄膜的结构体系限制是导致上述问题产生的主要原因。在此基础上,重点综述了国内外研究学者为提高铝合金表面沉积DLC薄膜的膜基结合力所采取的有效措施及结果,包括:通过基体前处理增强基体力学性能与改善宏观表面缺陷;采用PVD或其他表面处理方法制备一层或多层的中间过渡层,缓解DLC薄膜与铝合金基体结构、性能之间的差异;调控DLC薄膜组分与结构以降低残余应力。最后展望了在铝合金基体表面制备DLC防护薄膜的发展趋势。     

Surface-engineered metal-on-metal bearings improve the friction and wear properties of local area contact in total joint arthroplasty

Metal-on-metal articulating total joint arthroplasty has the potential to eliminate polyethylene-wear-induced osteolysis and aseptic loosening around the prosthesis. Metal surface coatings, however, are subject to delamination in areas of local contact. Various studies have been conducted to reduce metal wear debris and corrosion by introducing surface treatments.In this study we applied carbon ion implantation (CII) and diamond-like carbon (DLC) films to a cobalt-chrome alloy substrate by plasma source ion implantation. Once the films were prepared, we put them through simple geometry wear tests under high contact pressure (an average load of 1030 MPa) to establish the tribological properties during the phase of local contact that leads to severely increased wear in total joint arthroplasty. The CII-coated bearings showed less wear, lower friction coefficients, and higher resistance to catastrophic damage compared to uncoated Co-Cr alloy and DLC couples, even under high contact pressure. The CII-coated surface offers potential advantages as a hard coating for articulating joints.     

Ion beam energy effects on structure and properties of SiOx doped diamond-like carbon films

SiO_x doped diamond-like carbon (DLC) films were synthesized by direct ion beam from hexamethyldisiloxane vapor. Effects of ion beam energy were studied. Variation of atomic concentration of the oxygen versus carbon with ion energy has been observed. Raman scattering spectroscopy didn’t indicate essential changes in structure of the films deposited at different ion beam energies. The synthesized films were atomically smooth. Depending on the ion energy the refractive index of the SiO_x doped diamond-like carbon films varied within 2.1-2.5 and increased with increase of energy. The contact angle with water for all samples was only 61-64°.     

Use of near atmospheric pressure and low pressure techniques to modification DLC film surface

Diamond-like carbon (DLC) films have been use in numerous industrial applications due to its mechanical properties such as low friction coefficient, high hardness, and high adherence on different substrate materials. It has been demonstrated that the DLC surface can be modified with oxygen plasma treatment. The purpose of this paper is to study two kinds of surface treatments (atmospheric and low pressures) using oxygen gas for different etching exposure times in DLC films. Plasma durability along the time was also evaluated. DLC films were deposited using plasma enhanced chemical vapor deposition technique. The properties of DLC treated for both techniques in different exposure times were investigated through Raman, AFM and contact angle measurements. D band position slightly shifts toward lower wave numbers after oxygen plasma etching treatment whilst the surface becomes rougher, although the roughness values are still lower. A conventional wetting contact angle method was used to study the surface properties of DLC films with different treatments. The wetting contact angle reduced significantly due to the increase of carbon–oxygen sites on the surface.     

真空阴极弧离子镀类金刚石碳膜Raman光谱研究

分别采用带有和不带有弯曲弧磁过滤器的真空阴极弧离子镀方法，在不同镀膜电流以及不同基片偏流下分别制备了类金刚石碳膜，对比了不同结构下类金刚石碳膜的Raman光谱特点对其Raman光谱的D峰和G峰采用Gaussian-Lorentzion的几率分布进行了分峰，并着重讨论了基片偏流、弯曲磁场等沉积参数对膜结构的影响结果表明，氩分压对膜结构影响不大，较大的偏流以及弯曲磁场的加入均有利于sp^3杂化碳键的形成。     

掺磷四面体非晶碳薄膜的电学性能

采用过滤阴极真空电弧技术以PH_3为掺杂源,施加0—200 V基底负偏压,制备了掺磷四面体非晶碳(ta-C:P)薄膜,利用X射线光电子能谱(XPS)和Raman光谱研究ta-C:P薄膜的微观结构,通过测定变温电导率和电流-电压曲线,考察ta-C:P薄膜的导电行为。结果表明,磷掺入增加了薄膜中sp~2杂化碳原子含量和定域电子π/π~*态的数量,提高了薄膜的导电能力,且以-80 V得到的ta-C:P薄膜导电性能最好,在293—573 K范围内ta-C:P薄膜中的载流子表现出跳跃式传导和热激活传导两种导电机制,电流-电压实验证明ta-C:P薄膜为n型半导体材料。     

The influence of the surface structure of polyaniline films on the adsorption of influenza A viruses and antibodies to them

Adsorption of influenza A viruses and their antibodies on golden surfaces, thin films of polyaniline and polyaniline complex with polysulfonic acids, has been studied. The composition of interpolymer complexes was found to influence both the surface relief of synthesized films and the adsorption efficiency. Moreover, it has been shown that the adsorption of bio-objects increased with a growth of surface roughness of the polymer coatings. It has been suggested that this effect was caused by an tight contact between the studied bioobjects and the surface relief elements of close size. In addition, the surface protuberances can act as active centers of adsorption due to their larger accessibility. The results testify to the potential of application of films composed of interpolymer polyaniline complexes with a developed surface relief as a basis to prepare biosensors that are sensitive to viruses and antibodies.     

Characterization and analysis of DLC films with different thickness deposited by RF magnetron PECVD

Diamond-like carbon (DLC) films have excellent mechanical and chemical properties similar to those of crystalline diamond giving them wide applications as protective coatings. So far, a variety of methods are employed to deposit DLC films. In this study, DLC films with different thicknesses were deposited on Si and glass substrates using RF magnetron PECVD method with C4H10 as carbon source. The bonding microstructure, surface morphology and tribological properties at different growing stages of the DLC films were tested. Raman spectra were deconvoluted into D peak at about 1370 cm-1 and G peak around 1590 cm-1, indicating typical features of the DLC films. A linear relationship between the film thickness and the deposition time was found, revealing that the required film thickness may be obtained by the appropriate tune of the deposition time. The concentration of sp3 and sp2 carbon atoms in the DLC films was measured by XPS spectra. As the films grew, the sp3 carbon atoms decreased while sp2 atoms increased. Surface morphology of the DLC films clearly showed that the films were composed of spherical carbon clusters, which tended to congregate as the deposition time increased. The friction coefficient of the films was very low and an increase was also found with the increase of film thickness corresponding to the results of XPS spectra. The scratch test proved that there was good bonding between the DLC films and the substrates.     

Adhesion and composite micro-hardness of DLC and Si-DLC films deposited on nitrile rubber

Thin films of hydrogenated diamond-like carbon (DLC) and silicon (Si) doped diamond-like carbon (Si-DLC) have been deposited on acrylonitrile butadiene rubber (NBR) using a closed field unbalanced magnetron sputtering ion plating system. A sputter cleaning process was integrated into the deposition process so as to reduce the likelihood of re-contamination between the cleaning and deposition stages. The deposited coatings showed excellent adherence with an adhesion rating of 4 A for films with a Si-C interlayer. The composite micro-hardness was highest for DLC films at 15.5 GPa for indentation load of 147.1 mN using a Vickers micro-hardness tester. Tribological tests undertaken under normal load of 5 N using a pin-on-disc tribometer for all of the samples of DLC and Si-DLC films, with and without Si-C interlayer, show a friction increase between 0.25 and 0.4 to between 0.45 and 0.6. This friction increase has been related to the micro-hardness of the films.     

Structure and tribological properties of modified layer on 2024 aluminum alloy by plasma-based ion implantation with nitrogen/titanium/carbon

1　INTRODUCTIONGoodmachinability ,lowdensityandhighspecif icstrengthmakealuminumanditsalloysextensivelybeusedinmanyindustries ,especiallyinaviationandspaceflightindustry .Howeverlowsurfacehardnessandlowwearresistanceoftenlimittheirengineeringapplications .Nitrogenionimplantationintoalu minumanditsalloysoffersthepossibilityofapplica tionswherebothhighwearresistanceandlowdensityarerequired[15] .Moreover ,ourpreviousinvestiga tion[6 ,7] presentedthatwhenaluminumalloywasim plantedwithnitrogen…