溅射能量对WC/a-C：H薄膜结构与性能的影响

为探究溅射能量对WC/a-C:H薄膜结构与性能的影响,并讨论WC掺杂对a-C:H薄膜的影响。通过非平衡磁控溅射+等离子体增强化学气相沉积法(UBMS+PACVD),以WC靶作为溅射靶,C_2H_2为反应气体,通过调制溅射靶电流,在316不锈钢基体上制备WC/a-C:H系列薄膜。用场发射电镜、透射电镜、X射线衍射仪、XPS、拉曼光谱等对薄膜的微观结构和成分进行表征,用划痕仪、纳米硬度仪测试了薄膜的力学性能,用多功能摩擦机对薄膜的摩擦学性能进行分析。结果表明:WC主要以β-WC_(1-x)纳米晶的形式均匀分布在非晶碳中,随着溅射靶电流的上升,薄膜中W含量和膜基结合力呈上升趋势,在11A时上升至21.9%(摩尔分数)和18.6 N,而I_D/I_G比值和硬度逐渐降低至0.55和11 GPa。溅射靶电流为4 A时,WC/a-C:H薄膜表现出较好的磨损性能,摩擦因数低至0.15,磨损率为5.38×10^(-7) mm^3/(N?m)。

Nanocomposite TiC/a-C：H film prepared on titanium aluminium alloy substrates by PSII assistant MW-ECRCVD

Thin films of titanium carbide and amorphous hydrogenated carbon have been synthesized on titanium aluminium alloy substrates by PSII assisted MW-ECRCVD with a mirror field. The microstructure, chemical composition and mechanical property were investigated. Using XPS and TEM, the films were identified to be a-C：H film containing TiC nanometre grains （namely, the so-called nanocomposite structure）. The size of TiC grains of nanocomposite TiC/DLC film is about 5 nm. The nanocomposite structure has obvious improvement in the mechanical properties of DLC film. The hardness of a-C：H film with Ti is enhanced to 34 G Pa~ while that of a-C：H film without Ti is about 12 G Pa, and the coherent strength is also obviously enhanced at the critical load of about 35N.

High-Pressure Plasma Deposition of a-C:H Films by Dielectric-Barrier Discharge

The fabrication of a-C:H films from methane has been performed using dielectric-barrier discharges at atmospheric pressure. The effect of combined-feed gas, such as carbon dioxide, carbon monoxide or acetylene on the formation of a-C:H films has been investigated. It has been demonstrated that the addition of carbon monoxide or acetylene into methane leads to a remarkable improvement in the fabrication of a-C:H films. The characterization of carbon film obtained has been conducted using FT-IR, Raman and SEM.

乳化液环境中WC/a-C:H薄膜摩擦行为的研究

采用等离子体增强化学气相沉积复合磁控溅射法制备了WC/a-C:H薄膜.使用X射线衍射仪、扫描电镜、X射线光电子能谱、拉曼光谱和透射电镜表征了薄膜结构和组成,并使用球盘往复摩擦试验机测试薄膜在不同体系乳化液环境中的摩擦学性能.结果表明:WC/a-C:H薄膜具有典型的类金刚石结构,WC以β-WC1-x相的形式存在. WC在碳基薄膜中的掺杂使WC/a-C:H薄膜的硬度和弹性模量分别变化至11和140 GPa.油膜、水膜与转移膜的协同润滑效应能够提升其耐磨能力.适宜的浓度配比和薄膜表面石墨化程度是影响摩擦的关键因素.

Structure and tribological properties of Si/a-C:H(Ag)multilayer film in stimulated body fluid

Si/a-C:H(Ag)multilayer films with different modulation periods are prepared to test their potential applications in human body.The composition,microstructure,mechanical and tribological properties in the simulated body fluid are investigated.The results show the concentration of Ag first decreases and then increases with the modulation period decreasing from 984 nm to 250 nm.Whereas the C content has an opposite variation trend.Notably,the concentration of Ag plays a more important role than the modulation period in the properties of the multilayer film.The a-C:H sublayer of the film with an appropriate Ag concentration(8.97 at.%)(modulation period of 512 nm)maintains the highest sp3/sp2 ratio,surface roughness and hardness,and excellent tribological property in the stimulated body fluid.An appropriate number of Ag atoms and size of Ag atom allow the Ag atoms to easily enter into the contact interface for load bearing and lubricating.This work proves that the Ag nanoparticles in the a-C:H sublayer plays a more important role in the tribological properties of the composite-multilayer film in stimulated body fluid condition.

Optical Characterization of Amorphous Hydrogenated Carbon(a-C:H)Thin Films Prepared by Single RF Plasma Method

Methane （CH4） plasma was used to produce amorphous hydrogenated carbon （a- C：H） films by a single capacitively coupled radio frequency （RF） powered plasma system. The system consists of two parallel electrodes： the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground. Thin films were deposited on glass slides with different sizes and on silicon wafers. The influence of the plasma species on film characteristics was studied by changing the plasma parameters. The changes of plasma species during the deposition were investigated by optical emission spectroscopy （OES）. The structural and optical properties were analyzed via Fourier transform infrared （FTIR） spectroscopy, X-ray diffraction （XRD） and UV-visible spectroscopy, and the thicknesses of the samples were measured by a profilometer. The sp3/sp2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma. The film quality and deposition rate were both increased by raising the power and the flow rate.

Effect of Chromium on Structure and Tribological Properties of Hydrogenated Cr/a-C:H Films Prepared via a Reactive Magnetron Sputtering System

Hydrogenated Cr-incorporated carbon films （Cr/a-C：H） are deposited successfully by using a dc reactive mag- netron sputtering system. The structure and mechanical properties of the as-deposited Cr/a-C：H films are characterized systematically by field-emission scanning electron microscope, x-ray diffraction, Raman spectra, nanoindentation and scratch. It is shown that optimal Cr metal forms nanocrystalline carbide to improve the hardness, toughness and adhesion strength in the amorphous carbon matrix, which possesses relatively higher nano-hardness of 15. 7 CPa, elastic modulus of 126.8 GPa and best adhesion strength with critical load （Lc） of 36 N for the Cr/a-C：H film deposited at CH4 flow rate of 20sccm. The friction and wear behaviors of as-deposited Cr/a-C：H films are evaluated under both the ambient air and deionized water conditions. The results reveal that it can achieve superior low friction and anti-wear performance for the Cr/a-C：H film deposited at CH4 flow rate of 20sccm under the ambient air condition, and the friction coetllcient and wear rate tested in deionized water condition are relatively lower compared with those tested under the ambient air condition for each film. Superior combination of mechanical and tribological properties for the Cr/a-C：H film should be a good candidate for engineering applications.

Infrared and Optical Properties of Amorphous Fluorinated Hydrocarbon Films Deposited with the Method of ECR Plasma

Using CH4 and CF4 precursor gases, amorphous fluorinated hydrocarbon (a-C:F:H) films were prepared with the method of microwave electronic cyclotron resonant (ECR) plasma chemical vapor deposition. Deposition rate of the film firstly increases and then decreases with variable flow ratios R {[CF4]/([CF4] + [CH4]} due to the competition between deposition and etching process. Results from Fourier-transform infrared transmission spectroscopy of these films show that C-F bond configuration in a-C:F:H films evolves with the variable gas flow ratios R. The locations of the C-F peaks in IR spectra shift to higher frequency with the increase of R, and finally the structure in films with R >75% takes on a PTFE-like structure, which mainly consists of -CF2- chain. The change of optical band gap Eg deduced by a Tauc plot with R is also discussed.

Improved Hemolytic Performance of Blood Pump with Fluorine-Doped Hydrogenated Amorphous Carbon Coating

Fluorine-doped hydrogenated amorphous carbon (a-C:H:F) film was deposited on a flow-straightener, impeller and diffuser surface (SUS 304) of an enclosed-impeller type flow blood pump using the ionization deposition method with a source gas of C6F5H. The surface characteristics of the a-C:H:F film were examined using atomic force microscopy, X-ray photoelectron spectroscopy, and measurements of surface roughness, friction and surface potential. The a-C:H:F film tends to increase surface roughness and the negative surface charge. In addition, the surface energy and friction decrease with fluorine dopant in the a-C:H film. To estimate the hemolytic performance of a blood pump with the a-C:H:F film coating, the amount of hemolysis was measured using a mock circulatory system (in vitro test) with 500 mL of pig blood containing sodium citrate. In vitro test was conducted for 180 min with the blood flow and pump head maintained at 5 L/min and 100 mmHg, respectively. The a-C:H:F film coating reduced the amount of hemolysis and improved the hemolytic performance. Decreasing the surface energy and negative surface charge of the a-C:H:F film contributes to the improvement of the hemolytic performance. The a-C:H:F film coating is thus expected to be utilized in medical technology as a surface coating technology for artificial heart blood pumps.

Effect of Ti Incorporation on the Microstructure and Properties of the a-C:H Films Deposited by Magnetron Sputtering Technique

Amorphous hydrogenated carbon(a-C:H)and Ti-incorporated a-C:H(Ti/a-C:H)films were deposited by magnetron sputtering with a mixture gas of CH4 and Ar.The effect of the Ti incorporation on the chemical composition,microstructure and properties of the as-deposited and the annealed films were investigated by various techniques.It has been shown that the bonding structure and the internal stress were sensitive to the incorporation of the Ti atoms.The results of the XPS revealed that the concentration of Ti atom on the surface of the film increased when the Ti/a-C:H film annealed at 300oC.The tribologcial properties of the(Ti/)a-C:H films changed greatly after annealed,due to the graphitization,oxidation of carbon,and so forth.It compared and discussed in detail the change of the microstructure and properties of the a-C:H and Ti/a-C:H films before and after