类金刚石碳膜的热稳定性

总结了各种ＤＬＣ膜的热稳定性及分析手段,概述了加热退火情况下ＤＬＣ膜结构,内应力的变化,评述了国内的最新研究进展,并提出了有等进一步研究的问题。     

类金刚石碳膜的红外特性研究

用射频等离子体方法分解甲烷，在Ｇｅ片上制备了类金刚石碳（ＤＬＣ）膜。该膜折射率在２左右，具有较好的增透作用。双面镀ＤＬＣ膜系统在红外透射比，随膜厚不同，其极大值在３．８－１０．６μｍ范围内，在１０．６μｍ处红外透射比达９４．５％。镀制在直径为１００ｍｍＧｅ基片上的ＤＬＣ／Ｇｅ／ＤＬＣ膜系，在１０．６μｍ处，膜片中心的红外透射比为９３．９％，距中心不同距离的５个点的红外透射比为９１．１％，该膜系具有     

类金刚石碳膜的制备工艺

用射频－直流等离子体化学气相沉积法制备出类金刚石膜，用多因素和单因素正交试验设计方法对类金刚石的沉积工艺进行了研究，结果表明，极板偏压、真空度和气体成分是影响膜沉积速率的主要因素。沉积速率与ＰＶ成正比，且随反应气体深度单调增加，但当Ｃ２Ｈ２浓度低于１０％时，几乎不能成膜。     

过渡层对含氢非晶碳膜生长的影响

本文利用射频等离子体增强化学气相沉积（RFPECVD）工艺在不锈钢基底上制备了含氢非晶碳膜（a-C：H膜）。在沉积碳膜之前，首先在基底表面预先沉积了Ti／TiC、Ti／TiN和Ti／TiN／TiC等过渡层以提高膜基结合力。利用激光Raman光谱分析了过渡层对a-C：H膜生长过程及膜中sp^3含量的影响。实验结果表明，采用Ti／TiN／TiC过渡层时所制备的a-C：H膜中sp^3含量最多，同时膜基结合力最大。     

不锈钢表面ZSM-5分子筛膜的水热合成

沸石／金属复合膜材料由于具有诸多良好的性能,已显示出广阔的应用前景。利用水热法在不锈钢表面制备了ZSM-5分子筛膜,并考察了焙烧过程对膜基结合力的影响。通过划痕实验和扫描电镜分析,证明焙烧过程可使ZSM-5分子筛膜与不锈钢基体之间的膜基结合力显著增加。     

类金刚石膜研究进展

类金刚石膜具有高硬度、高热导率、低摩擦因数、良好的耐磨性能和化学惰性等优异的物化性能,在热沉、微电子、抗核加固、生物和汽车工业等领域具有重大的应用前景,近年来吸引了众多研究和关注。文章综述了类金刚石膜的研究进展和膜的成核机理,展示了类金刚石的应用前景,为该材料的研究和工业化应用提供思路和参考。     

类金刚石碳膜的红外特性研究

用射频等离子体方法分解甲烷，在Ge片上制备了类金刚石碳（DLC）膜。该膜折射率在2左右，具有较好的增透作用。双面镀DLC膜系统的红外透射比，随膜厚不同，其极大值在3．8～10．6μm范围内，在10．6μm处红外透射比达94．5％、镀制在直径为100mmGe基片上的DLC／Ge／DLC膜系、在10．6μm处，膜片中心的红外透射比为93．9％，距中心不同距离的5个点的红外透射比为91．1％，该膜系具有非常好的均匀性和红外增透性。通过计算获得了DLC膜的光学吸收系数曲线，该膜在3．8μm附近吸收系数为10cm-1；在10．6μm处吸收系数为600cm-1，并对该吸收曲线进行了讨论。     

无氢非晶金刚石膜耐磨性研究

用滤质阴极真空电弧(FCVA)离子镀技术在高速钢(W6M05Cr4V2)和不锈钢(0Cr18Ni9Ti)基体上沉积120～150nm非晶金刚石膜。用划痕法测定其结合力,平均临界载荷分别为19.15N(高速钢)和6.44N(不锈钢,CB工艺)。用栓盘摩擦试验测定镀膜的摩擦系数μ和耐磨寿命。摩擦系数μ为0.092～0.105,镀膜耐磨性比高速钢高106～319倍,比不锈钢高480～3600倍,而且镀膜质量稳定,重复性好。     

316不锈钢表面沉积厚类金刚石膜层的性能研究

采用脉冲辉光放电等离子体气相沉积法在316不锈钢表面沉积膜层较厚的类金刚石膜层。利用拉曼光谱仪(Raman)、X射线光电子能谱仪(XPS)、傅里叶变换红外光谱仪(FT-IR)、光学显微镜、显微硬度计和摩擦磨损实验机分别对膜层组成和微观结构及机械性能进行了表征。研究发现,通过脉冲辉光放电等离子体气相沉积法,在316不锈钢表面制备的类金刚石膜层光滑致密;Raman分析得到的ID/IG和IT/IG比值分别为0.72和0.22;FT-IR分析可知膜层含有较多的CHx组成的sp3键;摩擦磨损试验得到膜层的摩擦系数低至0.100,XPS分析膜层sp3含量高达60.7%和光学显微镜测量膜层的厚度达到7mm。由此可知沉积类金刚石膜层后,可以显著地改善316不锈钢表面的机械性能。     

Si过渡层对梯度影响类金刚石薄膜结合力的影响研究

实验利用双放电腔微波-ECR等离子体源设备,采用复合PVD（physical vapor deposition）和PECVD（plasma enhanced chemical vapor deposition）的方法, 先后在NiTi基体上沉积Si和Si/α-C∶H过渡层,然后制备类金刚石薄膜.Raman光谱和透射电镜表明制备的梯度薄膜是典型的类金刚石薄膜,划痕的测试结果表明, Si过渡层沉积时间影响着梯度类金刚石薄膜与NiTi合金基体之间的结合强度,当沉积时间在60min左右时可获得具有最好结合强度的梯度薄膜,而超过或低于这个时间值会导致膜基结合强度降低.     

Adhesive B-doped DLC films on biomedical alloys used for bone fixation

The long-term failure of the total hip and knee prostheses is attributed to the production of wear particles at the articulating interface between the metals, ceramics and polymers used for surgical implants and bone-fixtures. Therefore, finding an adhesive and inert coating material that has low frictional coefficient should dramatically reduce the production of wear particles and hence, prolong the life time of the surgical implants. The novel properties of the non-toxic diamond-like carbon (DLC) coatings have proven to be excellent candidates for biomedical applications. However, they have poor adhesion strength to the alloys and biomaterials. The addition of a thin interfacial layer such as Si, Ti, TiN, Mo and Cu/Cr and/or adding additives such as Si, F, N, O, W, V, Co, Mo, Ti or their combinations to the DLC films has been found to increase the adhesion strength substantially. In our study, grade 316L stainless steel and grade 5 titanium alloy (Ti-6Al-4V) were used as biomaterial substrates. They were coated with DLC films containing boron additives at various levels using various Si interfacial layer thicknesses. The best film adhesion was achieved at 8% and 20% on DLC coated Ti-6Al-4V and grade 316L substrates, respectively. It has been demonstrated that doping the DLC with boron increases their adhesion strength to both substrates even without silicon interfacial layer and increases it substantially with optimum silicon layer thickness. The adhesion strength is also correlated with the hydrogen contents in the B-DLC films. It is found to reach its maximum value of 700 kg/cm² and 390 kg/cm² at 2/7 and 3/6 for CH₄/Ar partial pressures (in mTorr ratio) for Ti-6Al-4V and 316L substrates, respectively.     

Carbon deposition on stainless steel in oxidising environments

Abstract

The formation of low-density carbon deposits onto metallic heat transfer surfaces in industrial environments of high carbon activity can have a deleterious effect on thermal efficiency. Often this deposition occurs under reducing conditions and involves carbide (typically of iron) formation as part of the process. It is possible, however, for filamentous carbon deposits to form at much higher oxygen potentials where carbide formation is not favoured thermodynamically. This study considers one such situation by examining the behaviour of a 20Cr25Ni austenitic steel used as fuel cladding in Advanced Gas-cooled nuclear reactors (AGRs). Carbon deposition has been produced in laboratory by exposure at 550°C to CO₂ containing 1%CO and 1000 vppm C₂H₄; the dissociation of the latter additive generates carbon activities much greater than unity. The oxygen potential of this gas is sufficient to oxidise iron and chromium, of the major alloy constituents, but not nickel. The deposition takes place onto substrates that are prepared as electron microscope samples which are subsequently examined by SEM and HREM (high resolution electron microscopy) techniques. The deposits formed consist of solid carbon filaments, approximately 30 nm in diameter, with turbostratic atomic layering. Each filament contains a 10–20 nm metallic nickel particle near its tip. It is argued, and supported by HREM evidence, that such particles are produced as a direct result of the oxidation of the alloy and that prior oxidation is necessary to produce the observed carbon deposition. It is also shown that inhibition of carbon deposition occurs when the oxygen potential of the depositing gas is increased sufficiently to oxidise nickel.     

不锈钢衬底上锆钛酸铅膜的制备

以改性二氧化锆为过渡层,用溶胶－凝胶法在不锈钢衬底上成功制备了锆钛比为52／48的锆钛酸铅膜,扫描电镜分析表明,膜的表面平整,无裂纹,X射线分析结果说明,经650℃退火30min后,膜为纯的钙钛矿相,以衬底为下电极、直径为0.32mm的金上电极,测量了0.8μm膜的电滞回线及其它性能,膜的剩余极化为18μC/cm^2。     

Tribological properties of multilayer DLC/W-DLC films on Si

Multilayer films of diamond-like carbon (DLC) and tungsten-containing diamond-like carbon (W-DLC) films were deposited onto silicon wafers using radio frequency chemical vapor deposition (RFCVD) and a magnetron sputtering method. The W-DLC layer was deposited on the silicon wafer with less than 60 W magnetron output. The DLC layer was then deposited on the W-DLC layer.Surface morphology was investigated by atomic force microscopy and the film structure by transmission electron microscopy. Friction tests for multilayered films were performed in a nitrogen atmosphere at room temperature using a ball-on-disk tribometer. A conventional stainless steel ball was used for the test.The surface profiles seen by atomic force microscopy showed that round-shaped clusters of around 100 nm were observed in just the single W-DLC layer. These clusters were considered to be tungsten or tungsten-carbon composites. In the case of the DLC/W-DLC multilayered structure, the top DLC layer covered the W-DLC single layer and smoothed the surface of the W-DLC film.Friction tests demonstrated that the friction coefficient of the W-DLC single layer was above 0.6 and increased gradually as the number of cycle increased. The W-DLC films partially broke down during our measurements. However the DLC/W-DLC multilayer films showed stable friction properties and were observed for up to 100,000 cycles. Their friction coefficient was typically less than 0.1 at 10 cm/s rotating speed. The DLC/W-DLC multilayer films exhibited stable low friction properties in a long term test under a nitrogen atmosphere.     

Production of high nitrogen surfaces on 2205 duplex stainless steel substrate using the PTA technique

Abstract

The plasma transferred arc technique has been used for the production of high nitrogen surfaces on 2205 duplex stainless steel substrates. Nitrogen was introduced into the melt using Ar+5%N₂ and Ar+10%N₂ gas mixtures. The nitrided surfaces are austenitic–ferritic and have a thickness of 1140±35 and 1650±31 μm respectively. The change of the austenite crystal lattice, due to the absorption of nitrogen, was determined by X-ray diffraction. Pin on disc tests showed that the wear resistance was increased. The corrosion in 3·5%NaCl and 1 N H₂SO₄ aqueous solutions was also slightly improved. Significant improvement was, however, observed in the pitting corrosion resistance of the nitrided surfaces, with regard to the 2205 duplex stainless steel substrate.     

玻璃及不锈钢衬底N型微晶硅薄膜的制备

利用射频等离子体增强化学气相沉积(RF-PECVD)技术,以PH3为掺杂剂,在浮法玻璃衬底和不锈钢衬底上制备了纳米级的n型微晶硅薄膜。采用Wvase32型椭圆偏振光谱仪、Reinishaw2000型拉曼(Raman)光谱仪和高阻仪对薄膜进行测试,以研究沉积条件对薄膜沉积速率、晶化率和暗电导特性的影响,并对沉积功率和沉积气压进行双因素优化,绘制了双因素相图。     

Interface structure of diffusion bonded duplex stainless steel and medium carbon steel couple

Diffusion bonding of duplex stainless steel to medium carbon steel was carried out with different temperatures for sound bonds. In the bonding process, relatively intermediate temperatures such as 750, 800, 850 and 900 °C were used with a bonding time of 30 min. In this study, microstructural changes and mechanical properties in the interface region of duplex stainless steel and medium carbon steel couples were determined. The results showed that, in interface region, Cr₂₃C₆ was formed on the stainless steel side, while ferrite formation was observed on the carbon steel side as a result of mutual diffusion of C and Cr.     

不锈钢真空钎焊

简述了不锈钢真空钎焊技术的应用、原理、工艺及设备情况,并概述了不锈钢真空钎焊技术的发展趋势.