Improvement of adhesion of DLC coating on nitinol substrate by hybrid ion beam deposition technique

Diamond-like carbon (DLC) films were prepared for a protective coating on nitinol substrate by hybrid ion beam deposition technique with an acetelene as a source of hydrocarbon ions. An amorphous silicon (a-Si) interlayer was deposited on the substrates to ensure better adhesion of the DLC films followed by Ar ion beam treatment. The film thickness increased with increase in ion gun anode voltage. The residual stresses in the DLC films decreased with increase in ion gun anode voltage and film thickness, while the stress values were independent of the radio frequency (RF) bias voltage. The adhesion of the DLC film was improved by surface treatment with argon ion beam for longer time and by increasing the thickness of a-Si interlayer.     

Metal-doped diamond-like carbon films synthesized by filter-arc deposition

Diamond-like carbon (DLC) thin films are extensively utilized in the semiconductor, electric and cutting machine industries owing to their high hardness, high elastic modulus, low friction coefficients and high chemical stability. DLC films are prepared by ion beam-assisted deposition (BAD), sputter deposition, plasma-enhanced chemical vapor deposition (PECVD), cathodic arc evaporation (CAE), and filter arc deposition (FAD). The major drawbacks of these methods are the degraded hardness associated with the low sp³/sp² bonding ratio, the rough surface and poor adhesion caused by the presence of particles. In this study, a self-developed filter arc deposition (FAD) system was employed to prepare metal-containing DLC films with a low particle density. The relationships between the DLC film properties, such as film structure, surface morphology and mechanical behavior, with variation of substrate bias and target current, are examined. Experimental results demonstrate that FAD-DLC films have a lower ratio, suggesting that FAD-DLC films have a greater sp³ bonding than the CAE-DLC films. FAD-DLC films also exhibit a low friction coefficient of 0.14 and half of the number of surface particles as in the CAE-DLC films. Introducing a CrN interfacial layer between the substrate and the DLC films enables the magnetic field strength of the filter to be controlled to improve the adhesion and effectively eliminate the contaminating particles. Accordingly, the FAD system improves the tribological properties of the DLC films.     

Electrochemical Corrosion Behavior of the DLC Coated and Uncoated NiTi Alloys

A dense and well-adhered diamond-like carbon （DLC） coating was prepared on the nickel-titanium （NiTi） alloys by plasma immersion ion implantation and deposition （PIIID）. Potentiodynamic polarization tests indicated the corrosion resistance of the NiTi alloys was markedly improved by the DLC coating. The Ni ions release of the NiTi alloys was effectively blocked by the DLC coating.     

Evaluation of pinhole defect in DLC film prepared by hybrid process of plasma-based ion implantation and deposition

Pinhole defect in diamond-like carbon (DLC) film prepared by a hybrid process of plasma-based ion implantation and deposition using toluene plasma was evaluated by the critical passivation current density in the anodic polarization method. The area ratio of pinhole defects to the SUS304 bare substrate was decreased exponentially with increasing DLC film thickness and reached about 3×10^-6% at film thickness. As a result, it is found that the corrosion resistance of DLC-coated specimens was improved with increasing film thickness. The production of an interfacial mixing layer by ion implantation from methane and acetylene plasmas between the DLC film and the substrate material reduced pinhole defects in the film.     

超高分子量聚乙烯表面金属化及类金刚石薄膜沉积复合处理研究

采用超高分子量聚乙烯(UHMWPE)表面金属化及类金刚石薄膜沉积复合处理工艺,提高超高分子量聚乙烯的耐磨性.首先采用磁过滤阴极真空弧源沉积技术(FCVA)在UHMWPE表面制备约30nm钛金属层,使UHMWPE表面金属化,然后再沉积DLC薄膜,研究结果表明,UHMWPE表面金属化后,DLC薄膜沉积过程中,电荷累积效应消...     

H13钢离子渗氮(PN)与类金刚石(DLC)复合处理的摩擦磨损性能研究

采用阳极层流离子源与非平衡磁控溅射结合的沉积方法在H13钢基体表面沉积出类金刚石膜(DLC),并对H13钢经不同表面预处理对后沉积的DLC膜的摩擦学性能进行了对比研究.结果表明:DLC膜结构致密,且DLC膜与梯度过渡层及基体三者之间结合牢固;H13钢经离子氮化后,梯度过渡层与氮化层间结合紧密,提高了膜与基体的承载能力;在保持相同摩擦速率的条件下,摩擦系数随着载荷的增加先增大后减小;H13钢离子渗氮处理后沉积的DLC膜其摩擦系数远小于未采用离子渗氮处理沉积的DLC薄膜.     

类金刚石薄膜对轴承钢表面机械性能和滚动接触疲劳寿命的影响

使用等离子体浸没离子注入与沉积(PIII&D)技术在轴承钢基体表面合成类金刚石(DLC)薄膜,研究了薄膜的结构和性能,结果表明,所制备的DLC薄膜主要是由金刚石键(sp3)和石墨键(sp2)组成的混合无定形碳,且sp3键含量大于10%,DLC膜层致密均匀,与基体结合良好,DLC膜具有很高的硬度和杨氏模量,分别达到40 GPa和430 GPa;其最低摩擦系数由基体的0.87下降到0.2,被处理薄膜试件在90%置信区间下的L10、L50、La和平均寿命L较基体分别延长了10.1倍、4.2倍、3.5倍和3.4倍,PIII&D轴承钢滚动接触疲劳寿命的分散性得到了显著改善.     

Adhesion property of SiOx-doped Diamond-like Carbon Films Deposited on Polycarbonate by Inductively Coupled Plasma Chemical Vapor Deposition

SiO_x-DLC (diamond-like coating) films as candidates for protection coating of polymers were prepared by using a pulse-biased inductively coupled plasma chemical vapor deposition system with acetylene, tetramethylsilane and oxygen gasses. Effects of the gas composition and O₂ plasma pre-treatment on adhesion of the SiO_x-DLC films were investigated. Adhesion strength of Si-DLC films (with 0% oxygen) was almost the same to that of undoped DLC films. By employing O₂-plasma pre-treatment, adhesion strength of the Si-DLC films was considerably improved, while that of the undoped DLC films was not. The SiO_x-DLC films with the carbon to oxygen (O/C) ratio of 0.15 showed adhesion strength as high as that of the Si-DLC films on the O₂-plasma pre-treated substrate. However, further improvement of adhesion strength of the SiO_x-DLC was not realized by employing the O₂-plasma pre-treatment. On the other hand, the SiO_x-DLC films showed favorable feature of high deposition rate and large optical band gap although higher O/C ratio (> 0.15) brought about poor adhesion strength of the films.     

涤纶材料表面类金刚石薄膜的沉积及其抗菌性能研究

采用乙炔等离子体浸没离子注入与沉积(PIII-D)，对医用涤纶(PET)缝合环材料进行表面改性，Raman光谱、X射线光电子能谱(XPS)和衰减全反射傅立叶变换红外光谱(ATR-FTIR)的分析结果表明：在涤纶材料表面有效地沉积了一层类金刚石(DLC)薄膜。原子力显微镜(AFM)的图像分析进一步证明表面平均粗糙度从58．9nm降低到11．2mm。细菌粘附实验结果证明沉积了类金刚石薄膜的表面对5种细菌——金黄色葡萄球菌(SA)、表皮葡萄球菌(SE)、大肠杆菌(EC)、绿浓杆菌(PA)和白色念殊菌(CA)的粘附均有明显抑制作用，其中从培养时间为15h的吸附情况比较来看，金黄色葡萄球菌的粘附率降低了70％．表皮葡萄球菌降低了86%。     

Effect of thick DLC coating on fatigue behaviour of magnesium alloy in laboratory air and demineralised water

Rotating bending fatigue tests have been performed using Diamond‐like carbon (DLC) coated specimens of a wrought magnesium alloy, AZ80A, in laboratory air and demineralised water and the effect of DLC coating on fatigue and corrosion fatigue behaviour was studied. Three film thicknesses of 3.5 μm, 13 μm, and 25 μm (two‐layer film) were evaluated and particular attention was paid to the role of thick DLC coating. In laboratory air, the fatigue strengths of the DLC‐coated specimens were higher than that of the substrate specimen and increased with increasing film thickness. This was because hard DLC coating with good adhesion suppressed the crack initiation due to cracking of inclusions or cyclic slip deformation on the substrate surface. In demineralised water, the fatigue strength of the 3.5‐μm DLC‐coated specimen was the same as that of the substrate specimen due to the penetration of the water through pre‐existing film defects, while the 13‐μm and 25‐μm DLC‐coated specimens showed increased corrosion fatigue strength with increasing film thickness and also exhibited nearly the same fatigue strength as in laboratory air except for a few premature failed specimens, indicating a potential of thick DLC coating or two‐layer coating for complete improvement of corrosion fatigue strength in aqueous environments.     

Adhesion studies of diamond-like carbon films deposited on Ti6Al4V substrate with a silicon interlayer

Diamond-like carbon (DLC) films have proven quite advantageous in many tribological applications due to their low friction coefficient, their extreme hardness, and more recently their high adherence on different substrate materials. However, for many applications, DLC films as thick as 2 μm are required, which cause high residual stress. In order to overcome this problem, this study observed the behavior of different thicknesses of silicon interlayer between DLC films and Ti6Al4V substrates. The study also analyzed the relation of growth parameters to the mechanical properties of DLC films. Silicon and DLC films were grown by using a rf-PECVD at 13.56 MHz with silane and methane atmospheres, respectively. The contribution of an interlayer thickness to the adhesion between the DLC films and Ti6Al4V substrate was evaluated by using a micro-scratch technique. The hardness and friction coefficient were evaluated by using microindentation and lateral force microscopy (LFM), respectively. Raman scattering spectroscopy was used to characterize the film quality. A correlation was found between the intrinsic stress and adhesion of DLC film and the parameters of the silicon interlayer growth. The addition of a silicon interlayer successfully reduced intrinsic stress of the films, even as measured by using a perfilometry technique.     

The study of adhesion and nanomechanical properties of DLC films deposited on tool steels

In this study, thin diamond-like carbon (DLC) films were deposited onto a steel substrate. By using the plasma immersion ion implantation (PIII) technique, a nitrogen layer was formed on the steel surface before depositing the DLC films. This PIII formed nitrogen layer, which acts as the buffer layer, has apparently increased the adhesion between the DLC film and the steel substrate. The microstructures, the nanomechanical properties, and the adhesion of the DLC were investigated by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), nanoindentation, and nanoscratch. Results show that the hardness and Young's modulus were significantly improved, up to 2 to 9 times; while the implantation depth and the microstructure of the nitrogen layers vary with nitrogen/hydrogen ratio (N:H = 1:0, 1:1, 1:3). Raman analyses indicate that the I(D)/I(G) ratio increases with the thickness of DLC film. By using the PIII technique in the steel substrate, the adhesion of the DLC film onto the substrate is greatly enhanced, and wear resistance is elevated if the DLC film is sufficiently thick.     

基于RFPECVD方法不锈钢上沉积类金刚石薄膜的机械与摩擦特性

讨论用射频等离子体增强化学气相沉积(RFPECVD)工艺,在室温下实现在1Cr18Ni9Ti不锈钢基底上镀类金刚石(DLC)膜.为提高DLC膜的结合力,首先在不锈钢基底上沉积Ti/TiN/TiC功能梯度膜.借助所设计的界面过渡层,成功地在不锈钢基底上沉积了一定厚度的DLC膜.通过优化沉积参数,所沉积的DLC膜在与100Cr6钢球对磨时摩擦系数低于0.020.在摩擦过程中DLC膜的磨损机制借助SEM、Raman分析进行了研究.     

非平衡磁控溅射类金刚石薄膜的特性

非平衡磁控溅射(UBMS)结合了普通磁控溅射(MS)和离子束辅助沉积的优势,易于实现离子镀,近年来得到了广泛的应用.采用该技术制备的类金刚石薄膜(DLC)具有许多独特的性质.本文研究了非平衡磁控溅射技术制备DLC薄膜的光学、机械,电学和化学性能.研究表明,非平衡磁控溅射制备的DLC膜具有较宽的光谱透明区,且表面光滑、摩擦系数小、耐磨损、抗化学腐蚀,同时具有较高的电阻率和良好的稳定性.     

Characterization and tribological application of diamond-like carbon (DLC) films prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) technique

Diamond-like carbon (DLC) films were successfully prepared on glass substrates and surfaces of selenium drums via radio frequency plasma enhanced chemical vapor deposition method. The microstructure, surface morphology, hardness, film adhesion, and tribological properties of the films were characterized and evaluated by X-ray photoelectron spectroscopy, atomic force microscopy, and micro-sclerometer and friction-wear spectrometer. The results showed that DLC films have smooth surfaces, homogeneous particle sizes, and excellent tribological properties, which can be used to improve the surface quality of the selenium drums and prolong their service life.     

Fabrication of high frequency ZnO thin film SAW devices on silicon substrate with a diamond-like carbon buffer layer using RF magnetron sputtering

Diamond-like carbon (DLC) film is a promising candidate for surface acoustic wave (SAW) device applications because of its higher acoustic velocity. A zinc oxide (ZnO) thin film has been deposited on DLC film/Si substrate by RF magnetron sputtering; the optimized parameters for the ZnO sputtering are RF power density of 0.55 W/cm², substrate temperature of 380 °C, gas flow ratio (Ar/O₂) of 5/1 and total sputter pressure of 1.33 Pa. The results showed that when the thickness of the ZnO thin films was decreased, the phase velocity of the SAW devices increased significantly.     

等离子体源离子注入法制备类金刚石薄膜

用等离子体源注入(PSII)在Si(100)上制备类金刚石膜，放电气体采用CH4，用微波电子回旋共振(ECR)产生等离子体。将-20～-30kV的高压加在衬底上，来提高离子的能量。通过Raman光谱和FT-IR光谱检测了类金刚石膜的化学组成及状态，并对其机械性能和表面形貌进行了检测。结果显示，硅片硬度和摩擦因数得到了改善，用PSII能够制备出性能优良的膜，可以将其应用到微电子器件(MEMS)上去。     

T-shape filtered arc deposition system with built-in electrostatic macro-particle trap for DLC film preparation

A T-shape filtered arc deposition system (T-FAD) is a powerful tool to prepare high-quality diamond-like carbon (DLC) films. Most macro-particles (droplets) emitted from the graphite cathode are caught at the extension duct of the droplet catcher or collector facing the cathode, and then the clean plasma bent 90° is transported toward the substrate. However, further droplet reduction is still required in order to realize a higher quality film without droplet incorporation. In the present study, T-FAD employed an electrostatic droplet trap (ES-trap). A cylindrical ES-trap was placed in the extension duct part of the T-shape duct of an electromagnetic plasma transportation and droplet filter. The ion current at the exit of the T-filter duct and the current flowing to the ES-trap were measured as a function of the ES-trap bias voltage for various ES-trap positions. The deposition rate and number of droplets were also measured. As a result, it was found that the optimum voltage of the ES-trap was + 35 V and that it was better to place the ES-trap closer to the plasma beam in order to obtain fewer droplets on the film without an excessive decrease in the deposition rate. In the optimum condition, the number of droplets on the DLC film prepared with ES-trap was reduced to 1/3 of that without the ES-trap.     

Wear behaviour and rolling contact fatigue life of Ti/TiN/DLC multilayer films fabricated on bearing steel by PIIID

In order to improve the friction and wear behaviours and rolling contact fatigue (RCF) life of bearing steel materials, Ti/TiN/DLC (diamond-like carbon) multilayer hard films were fabricated onto AISI52100 bearing steel surface by plasma immersion ion implantation and deposition (PIIID) technique. The micro-Raman spectroscopy analysis confirms that the surface film layer possess the characteristic of diamond-like carbon, and it is composed of a mixture of amorphous and crystalline phases, with a variable ratio of sp²/sp³ carbon bonds. Atomic force microscope (AFM) reveals that the multilayer films have extremely smooth area, excellent adhesion, high uniformity and efficiency of space filling over large areas. The nanohardness (H) and elastic modulus (E) measurement indicates that the H and E of DLC multilayer films is about 32 GPa and 410 GPa, increases by 190.9% and 86.4%. The friction and wear behaviours and RCF life of DLC multilayer films specimen have also been investigated by ball-on-disc and three-ball-rod fatigue testers. Results show that the friction coefficient against AISI52100 steel ball decreases from 0.92 to 0.25, the longest wear life increases nearly by 22 times. In addition, wear tracks of the PIIID samples as well as wear tracks of the sliding steel ball were analyzed with the help of optical microscopy and scanning electron microscopy (SEM). The L₁₀, L₅₀, L_a and mean RCF life L of treated bearing samples, in 90% confidence level, increases by 10.1, 4.2, 3.5 and 3.4 times, respectively. Compared with the bearing steel substrate, the RCF life scatter extent of Ti/TiN/DLC multilayer films sample is improved obviously.     

Deposition of diamond like carbon (DLC) and C-N films using ion beam assisted deposition (IBAD) technique and evaluation of their properties

Diamond like carbon films and C-N films were prepared using ion beam assisted deposition technique (IBAD). Tribological properties were studied by subjecting DLC coated films to the accelerated wear tests. These tests indicated a significant improvement in the mechanical surface properties of glass by DLC coating. Better wear features were obtained for thinner DLC coating as compared to the thicker ones. We also studied the optical properties and obtained a band gap of 1·4 eV for these films. An attempt was made to prepare C₃N₄ films by using IBAD. We observed variation in the nitrogen incorporation in the film with the substrate temperature.