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.

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.

a-C∶F∶H films prepared by PECVD

Fluorinated amorphous hydrogenated a-C∶F∶H carbon thin films were deposited using radio frequency plasma enhanced chemical vapor deposition（RF-PECVD） reactor with CF4 and CH4 as source gases and were annealed in a N2 atmosphere. The properties of these films were evaluated by FTIR spectrometry, UV-VIS spectrophotometry and single-wavelength spectroscopic ellipsometry. A correspondence relativity connection between the deposition rate and technology was found. The chemical bonding structures and the content of CHx and CFx in the films are transformed and the optical band gap decreases monotonically with increasing temperature after annealing. The dielectric constant is increased with decreasing content of F in the films and the optical band gap is decreased with decreasing the content of H in the film.

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.

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.

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.

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.

a-C∶F∶H薄膜的化学键结构

使用CF4和CH4为源气体,利用射频等离子体增强化学气相沉积法,制备了a-C∶F∶H薄膜样品。采用拉曼光谱仪、傅里叶变换红外光谱仪、X射线光电子能谱仪(XPS)对薄膜的结构进行了测试和分析。研究发现:该膜呈空间网状结构,膜内碳与氟、氢的结合主要以sp3形式存在,而sp2形式的含量相对较少;在薄膜内主要含有C—Fx(x=1,2,3)、C—C、C—H2、C—H3等以及不饱和C C化学键;同时,薄膜中C—C—F键的含量比C—C—F2键的含量要高。在不同功率下沉积的薄膜,其化学键结构明显不同。

微波ECR-CVD法制备a-C:F:H膜的红外吸收及其光学带隙

改变CHF3 CH4 流量比R =[CHF3] ([CHF3]+[CH4 ]) ,采用微波电子回旋共振等离子体化学气相沉积 (MWECR CVD)方法沉积a C :F :H薄膜。a C :F :H薄膜的结构和光学带隙使用傅立叶变换红外光谱和紫外 可见光谱来表征。红外结果表明 ,在低流量比R(R <6 4 % )下 ,薄膜的红外特征结构主要以 CF(10 6 0cm- 1 ) , CF2(112 0cm- 1 )以及 CHx(2 80 0～ 30 0 0cm- 1 )的伸缩振动为主 ;在高流量比R(R >6 4 % )下 ,薄膜表现为类聚四氟乙烯(PTFE)的结构特征 ,典型的红外特征峰是位于 12 2 0cm- 1 处的 -CF2 反对称伸缩振动。薄膜的光学带隙Eg 随流量比R的变化表现为先降后升。进一步研究表明 ,薄膜中的H和F浓度调制着薄膜的CC共轭双键结构 ,使光学带隙Eg 从 2 37到 3

真空退火对a-C:F:H薄膜的结构与光学带隙的影响

使用CF4和CH4为源气体 ,利用射频等离子体增强化学气相沉积 (RF PECVD)法制备了掺氟非晶碳 (a C :F :H)薄膜 ,并在N2 气氛中进行了不同温度的退火。用原子力显微镜 (AFM)观察了薄膜在退火前后表面形貌的变化 ,发现退火后薄膜表面变得平坦 ,疏松。用紫外 -可见光透射光谱 (UV VIS)并结合傅里叶变换红外光谱 (FTIR)和喇曼 (Raman)光谱对薄膜进行了分析 ,获得了薄膜化学键结构和光学带隙的变化情况 ;发现薄膜的化学键结构和光学带隙与真空退火密切相关 ,高温退火后薄膜化学键结构 :CHx(x=1,2 ,3下同 )、F -芳基、CF2 和CF等基团的含量改变 ;薄膜的光学带隙决定于CHx、退火后CHx 含量减少导致薄膜光学带隙的减小。

功率和温度对a-C:F:H膜表面形貌和结构的影响

分析薄膜的表面形貌对其生长机理和光学性质研究有着十分重要的作用。本文使用CF4和CH4为源气体,利用射频等离子体增强化学气相沉积(RF-PECVD)法在不同射频功率和沉积温度下制备了掺氟氢化无定形碳(a-C∶F∶H)薄膜,并在N2气氛中进行了不同温度的退火处理。用原子力显微镜(AFM)和扫描电子显微镜(SEM)观察了薄膜表面形貌,发现低功率下沉积的薄膜表面均匀性好、缺陷少;在低温下沉积的薄膜表面光滑,而高温下粗糙;真空低温退火可使薄膜表面形貌得到改善,但薄膜内空洞增加,退火温度过高,薄膜的结构发生变化,且在薄膜表面发生皲裂现象。用R am an光谱对薄膜内的结构变化进行了进一步的分析。

高频溅射α-Si:F,H薄膜光电导的实验与计算

通过对射频溅射RF a-Si:F,H薄膜样品光电导随入射光的波长、光强以及温度变化的测量,定量地考察了带隙、带尾态的宽度和带隙中悬键态密度与氟含量的关系,给出了氟原子在网络中一种可能的分布形式。按照Rose模型,计算了电光导随温度的变化关系,给出了局域态分布的位置、高度、宽度以及俘获截面等参量,理论计算与实验符合较好。

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

Thermal Stability and Tribological Properties of Fluorinated Amorphous Carbon Thin Films Doped With Nitrogen

Nitrogen doped fluorinated amorphous carbon thin films(a-C:N:F)were prepared by radio frequency plasma enhanced chemical vapor deposition(rf-PECVD)under different deposited condition usingCH_4,CF_4,and N_2 as source gases.The thin films were annealed at different temperature.The influence of doped nitrogen on the chemical structure, tribological and thermal properties of thin films were investigated by Atomic force microscopy(AFM),Fourier transform infrared absorption spectrometry(FTIR),X-ray photoelectron spectrum spectra(XPS),and thermogravimetry(TG).The results indicated that the thin films presence a compact and smooth morphology surface after the nitrogen doped.After incorporation of nitrogen,the H atoms are replaced partially by the N atoms in the thin films.The degree of cross-linking of the carbon network in the thin films is enhanced.The chemical bonds of C=N,C≡N,and C—N_x(x=1,2,3) have formed in the films.The relative content of sp^2 graphite phase increases.The thermal stability temperature of the films deposited at r=0.5(r=N_2/[CF_4+CH_4+N_2])is 420℃.The tribological properties improve greatly,and the friction coefficient of the a-C:N:F thin films ranges approximately from 0.20 to 0.36.

不同CHF_3/CH_4流量比下沉积a-C∶F∶H薄膜键结构的红外分析

通过微波电子回旋共振等离子体化学气相沉积方法使用CH4 CHF3源气体制备a C∶F∶H薄膜 .红外结果表明 ,a C∶F∶H薄膜随着流量比R =[CHF3] [CHF3]+[CH4])的变化存在结构上的演变 ,R <6 4%时 ,薄膜主要是以类金刚石 (DLC)特征的结构为主 ;当R >6 4%时 ,薄膜表现为一个类聚四氟乙烯 (PTFE)的结构 ,结构单体主要为 CF2 .同时这种结构上的变化影响着薄膜的光学带隙 .在类DLC特征结构区 ,Eg 随着流量比的增加而下降 ,而在类PTFE区 ,Eg 则随着流量比的上升而上升 .a C∶F∶H薄膜在R >92 %时透射率接近 10 0 %

ECR-CVD法制备的a-C:F:H薄膜在N_2气氛中的热退火研究

改变CHF3 CH4源气体流量比 ,使用微波电子回旋共振化学气相沉积方法 (ECR CVD)制备了具有不同C—F键结构的a C :F :H薄膜 ,着重研究了退火对其结构的影响 .结果显示薄膜的厚度及其光学带隙E0 4随退火温度的上升均呈现了不同程度的下降 .借助于红外吸收光谱和所提出的热解模型解释了产生这种关系的结构上的根源 .

源气体对沉积的a-C∶F∶H薄膜结构的影响

采用微波电子回旋共振等离子体化学气相沉积 (MWPECRCVD)方法 ,使用不同的源气体 (CHF3 CH4 ,CHF3 C2 H2 ,CHF3 C6 H6 )体系制备了a C∶F∶H薄膜 .由于CH4 ,C2 H2 ,C6 H6 气体在等离子体中的分解反应不同导致了薄膜的沉积速率和结构上的差异 .红外吸收谱的结果表明 ,用C6 H6 CHF3作为源气体沉积的薄膜中几乎不含H ,而用C2 H2 CHF3所沉积的薄膜中的含氟量最高 ,其相应的C F振动峰位向高频方向偏移 .薄膜的真空退火结果表明 ,a C∶F∶H薄膜的热稳定性除了取决于薄膜的CC键浓度外 ,还与CC键和其他键结构的关联有关 ,此外 ,源气体对薄膜的F

免耕覆盖与生物炭对黑垆土团聚体稳定性和腐殖质性质的影响

【目的】研究免耕条件下,长期采用不同的土壤覆盖方式及配合施用生物炭对渭北旱塬农田土壤团聚体稳定性和腐殖质性质的影响,为选择适合的耕作管理措施提供理论依据。【方法】基于连续18年田间定位试验,选择其中免耕条件下的无覆盖(NT)、施用生物炭(NB)、秸秆覆盖(NS)、地膜覆盖(NP)、秸秆地膜二元覆盖(NSP) 5个处理,采集0—10、10—20 cm土层土壤样品,通过干筛+湿筛法分为粉黏粒(<0.053 mm)、微团聚体(0.053~0.25 mm)、细大团聚体(0.25~2 mm)、粗大团聚体(>2 mm)共4个团聚体粒级,并测定了各粒级团聚体中有机碳和腐殖质组分含量。【结果】1)与NT处理相比,NS处理各粒径团聚体胡敏酸含量(0.93%~92.6%)和富里酸含量(1.8%~327.5%)显著增加且增幅最大,NSP处理各粒径团聚体有机碳含量显著提高了1.6%~30.5%;NB处理各粒径团聚体有机碳含量(39.90%~161.8%)及胡敏素含量的增幅最大,0—10 cm土层胡敏素含量显著提高了87.2%~271.7%。与NT相比,NS、NSP和NB处理均提高了土壤团聚体的稳定性和玉米籽粒产量,其中NSP处理的提升效果最显著,0—10、10—20 cm土层土壤团聚体平均重量直径(MWD)分别增加了48.6%和73.5%,几何平均直径(GMD)分别增加了59.2%和63.1%,2021年玉米籽粒产量增加了25.8%。2)各粒径水稳性团聚体有机碳中,均以胡敏素的比例最高,达37.6%~91.3%。与NT相比,NB处理显著提高了大部分粒径水稳性团聚体腐殖质的胡敏酸与富里酸之比(HA/FA),其中在0—10 cm土层微团聚体提高幅度最大,为80.2%,地膜覆盖(NP和NSP处理)降低了腐殖质HA/FA (6.8%~27.6%),各处理粉黏粒胡敏酸E4/E6值显著降低(4.2%~6.6%)。【结论】免耕条件下,秸秆覆盖和施用生物炭(NS、NSP和NB)可提升各粒径团聚体的有机碳含量,提高团聚体的稳定性和玉米产量,但对有机碳的腐殖化程度影响不同。单独秸秆覆盖提升黑垆土腐殖质的胡敏酸和富里酸含量效果最大,生物炭施用主要提升了各粒径团聚体有机碳中的胡敏素含量和胡敏素比例,秸秆和地膜二元覆盖对团聚体的稳定性和玉米籽粒产量的提升幅度最大,而且能够提高有机碳含量,是免耕条件下最佳处理。

谈通用厂房设计中的几个问题

通过实例简介了工业厂房通用性的设计方法， 及厂房适应工业发展需求的关键因素。