Carbon coatings for fusion applications

The use of low atomic number material coatings in a fusion reactor plasma chamber may ease concern over maintaining plasma purity. A deposition process involving the discharge activated deposition of carbon coatings from methane at about 1 Pa pressure has been investigated. A coating of thickness 10 μm on copper has survived 1000 cycles of pulsed thermal heating at 37 MW m^-2 with only minor flaking. The surface damage of similar coatings on stainless steel surfaces has been investigated for irradiation with 20, 40, 60 and 120 keV D⁺ and He⁺ ions at ambient temperature. Scanning electron microscopy of irradiated surfaces revealed no significant surface damage for either D⁺ or He⁺ irradiation with energies of 40 and 60 keV for doses of 4 × 10²² and 8.1 × 10²² ions m^-2 respectively. For 120 keV D⁺ and He⁺ irradiations for a dose of 2.2 × 10²³ ions m^-2, surface damage in the form of ridges was observed. A comparison of the results for carbon coatings with those obtained for ATJ graphite reveals that this type of graphite shows surface damage for all irradiations performed, while the carbon coating appears to be more resistant to damage for many of these irradiations. These results reflect favorably on the possible use of these coatings on various components in the plasma chamber of a fusion reactor.     

防氚渗透涂层制备技术的研究进展

在聚变堆研究中,聚变环境中涂层材料的防氚渗透问题是聚变堆材料研究的重要课题之一.主要介绍目前常用的几种防氚渗透涂层制备技术的研究进展,并提出利用双辉技术制备梯度氧化铝涂层在316L不锈钢表面形成Al2O3和SiC复合抗氚渗透层的新技术.     

Systematic Study of Nanocrystalline Plasma Electrolytic Nitrocarburising of 316L Austenitic Stainless Steel for Corrosion Protection

A number of studies have been reported on the use of nanocrystalline plasma electrolytic nitrocarburising technology for surface hardening of stainless steels for higher corrosion resistance resulted from this technique. However, very few studies have focused on the optimization of the nanocrystalline plasma electrolytic nitrocarburising process parameters. In this study, a design of experiment （DOE） technique, the Taguchi method, has been used to optimize the nanocrystalline plasma electrolytic nitrocarburising not only for surface hardening but also for the corrosion protection of 316L austenitic stainless steel by controlling the coating processes factors. The experimental design consisted of four factors （Urea concentration, electrical conductivity of electrolyte, voltage and duration of process）, each containing three levels. Potentiodynamic polarization measurements were carried out to determine the corrosion resistance of the coated samples. The results were analyzed with related software. An analysis of the mean of signal-to-noise （S/N） ratio indicated that the corrosion resistance of nanocrystalline plasma electrolytic nitrocarburised 316L stainless steel was influenced significantly by the levels in the Taguchi orthogonal array. The optimized coating parameters for corrosion resistance are 1150 g/L for urea concentration, 360 mS/cm for electrical conductivity of electrolyte, 260 V for applied voltage, 6 min for treatment time. The percentage of contribution for each factor was determined by the analysis of variance （ANOVA）. The results showed that the applied voltage is the most significant factor affecting the corrosion resistance of the coatings.     

沉积扩散法制备含银抗菌不锈钢工艺研究

采用沉积扩散法制备含银抗菌不锈钢层,通过抗菌试验、盐干湿循环腐蚀试验、SEM、XPS等检测手段,研究了沉积扩散工艺制备含银抗菌不锈钢的抗菌性能、耐蚀性能及银在不锈钢基体中的分布状态和价态.结果表明,基材表面化学镀银后经离子轰击抗菌处理(工艺参数:电压1.25 kV,电流3 A,气流量20～60 mL/min,时间4 h),所得含银抗菌不锈钢的杀菌率达到99%以上,耐蚀性能没有降低,银在基体中呈弥散状态分布,其价态为零价态.     

Preparation and magnetic characterization of core–shell structure stainless steel/silica nanoparticles

SiO₂-coated martensite stainless steel nanoparticles were prepared using wire electrical explosion technique combined with sol–gel technique, and their structural and magnetic properties were studied. The coating silica on stainless steel nanoparticles was based on the use of silane coupling agent 3-mercaptopropyltrimethoxysilane (HS-(CH₂)₃Si(OCH₃)₃, MPTS) as a primer to render the stainless steel surface vitreophilic, thus rendering stainless steel surface compatible with silica. The control over the silica coating layer thickness can be achieved by varying the reaction time. For stainless steel nanoparticles, their saturation and remnant magnetizations decreased upon silica coating, and their saturation magnetizations obviously decreased with increasing the thickness of SiO₂ coating layer. These stainless steel/silica core–shell nanoparticles can be utilized as precursors for making property-tunable magnetic nanoparticles, thin films, and multilayered core–shell structure nanocomposites.     

奥氏体不锈钢离子渗碳后的腐蚀行为

为了提高奥氏体不锈钢零件的使用寿命,利用低温离子渗碳技术对AISI 316L奥氏体不锈钢进行了表面渗碳处理.用X射线衍射仪和光学显微镜分析了渗碳层的微观组织结构,用显微硬度计测试了渗碳层的硬度分布,通过电化学极化曲线测试技术和化学腐蚀试验研究了离子渗碳AISI 316L不锈钢的腐蚀行为.渗碳层为单相碳过饱和奥氏体固溶体,由此明显提高了AISI 316L不锈钢的抗腐蚀性能,渗碳层硬度梯度平缓,表面显微硬度高达900 HV.结果表明,奥氏体不锈钢低温离子渗碳处理不仅提高了其表面硬度,而且提高了不锈钢表面的耐腐蚀性能,从而提高了其使用寿命.     

不锈钢的同步辐射光致脱附

电子储存环真空室壁及相连光束线的同步辐射光致脱附 (PSD)严重影响着束流质量和寿命。不锈钢是加速器真空室最常用的材料 ,合肥光源的真空系统即为不锈钢结构。合肥光源在B6a光出口建立了PSD光束线 ,选用长 12 1cm ,内径8 6cm的 30 4L不锈钢真空室作为首件样品 ,用于测试不锈钢不同表面状态的脱附情况 ,结果表明经辉光放电处理的表面脱附系数最低。     

Effect of hydrogen plasma pretreatment on the growth of silicon nanowires and their employment as the anode material of lithium secondary batteries

Silicon nanowires were grown from a silane and argon gas mixture directly on a stainless steel substrate by radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD) and used without any further treatment as the anode in the fabrication of lithium ion batteries. It was found that suitable pretreatment of the stainless steel substrate was required for the satisfactory growth of the silicon nanowires. In this study, the substrates were polished, etched in HF solution, coated with an aluminum catalyst layer with a thickness of c.a. 10 nm and then treated with a hydrogen plasma before the growth of the silicon nanowires. SEM (Scanning Electron Microscopy) and AFM (Atomic Force Microscopy) analyses showed that the grain size and surface roughness were increased after the hydrogen plasma pretreatment. The electrochemical performance of the silicon nanowires anode was also improved when the aluminum coated stainless steel substrate was exposed to the plasma for 20 min or longer; the initial coulombic efficiency was increased from 69.7% to 82% at a current density of 30 mA cm(-2).     

Formation of stainless steel layer on mild steel by welding arc cladding

The discrete microstructural characterization and the formation of stainless steel layer on mild steel where produced in cladding deposits, and fusion boundary region were investigated using tungsten inert gas (TIG) arc, high current pulsed arc and constricted plasma arc. The experimental procedure involved making bead-on-plate method for controlled travel speed, employing filler metal by using tungsten inert gas arc, pulsed current gas tungsten arc and transferred plasma arc, with subsequent sectioning and examination of the reaction interface. For TIG arc cladding, using filler metal of small diameter the deposit does not become stainless steel, but on using 3.2 mm diameter filler metal it becomes stainless steel with less than 50% dilution. For pulsed arc cladding, the complete stainless steel is not obtained on account of the existence of an incomplete mixture, particularly at the fusion boundary region. However, on using a large diameter filler metal at a pulse frequency of 500 Hz, the complete stainless steel microstructure has been accomplished. The plasma arc cladding can be achieved in such a way that the conversion into stainless steel on the mild steel surface — which is the microstructures of cellular austenite in cladding deposit and cellular dendritic austenite containing δ or σ-phase in fusion boundary region — is possible irrespective of the melt penetration and the dilution. The following conditions were found to be beneficial for the formation of stainless steel microstructure layer on the mild steel: using large diameter filler metal, below 50% dilution, and further rendering arc localized and constricted.     

Biocompatibility studies of low temperature nitrided and collagen-I coated AISI 316L austenitic stainless steel

The biocompatibility of austenitic stainless steels can be improved by means of surface engineering techniques. In the present research it was investigated if low temperature nitrided AISI 316L austenitic stainless steel may be a suitable substrate for bioactive protein coating consisting of collagen-I. The biocompatibility of surface modified alloy was studied using as experimental model endothelial cells (human umbilical vein endothelial cells) in culture. Low temperature nitriding produces modified surface layers consisting mainly of S phase, the supersaturated interstitial solid solution of nitrogen in the austenite lattice, which allows to enhance surface microhardness and corrosion resistance in PBS solution. The nitriding treatment seems to promote the coating with collagen-I, without chemical coupling agents, in respect of the untreated alloy. For biocompatibility studies, proliferation, lactate dehydrogenase levels and secretion of two metalloproteinases (MMP-2 and MMP-9) were determined. Experimental results suggest that the collagen protection may be favourable for endothelial cell proliferation and for the control of MMP-2 release.     

等离子喷涂WC/18Co涂层微动磨损机理的研究

研究了等离子喷涂WC/18Co涂层的微动磨损机理,结果表明,涂层的微动磨损开始阶段以粘着磨损为主,涂层硬度高,抗粘着能力强,磨损轻微;稳定阶段以疲劳脱层和脆性开裂剥落为主,涂层脆性大,喷涂粒子间结合强度低,容易磨损。喷涂层内部的氧化物夹杂是造成涂层抗微动磨损能力不足的主要原因。     

Ni60喷焊层与ZG06Cr13Ni5Mo抗气蚀性能的研究

采用火焰喷焊法在低碳钢试样表面制备了Ni 60喷焊层,与水力机械材料ZG06Cr13Ni5Mo的抗气蚀性能进行对比.借助光学显微镜、X射线衍射仪、显微硬度计、磁致伸缩气蚀仪等设备对涂层的组织、结构和性能进行了研究,利用扫描电镜对气蚀形貌进行了观察.结果表明:Ni 60喷焊层组织较细,显微硬度远高于ZG06Cr13Ni5Mo;其抗气蚀性能和ZG06Cr13Ni5Mo相比有所提高.     

Stellite 21 coatings on AISI 410 martensitic stainless steel by gas tungsten arc welding

Abstract

Degradation of AISI 410 martensitic stainless steel, a typical alloy for many applications such as steam turbine blade, could impair its efficiency and lifetime. To overcome this problem, critical surfaces could be modified by weld cladding via gas tungsten arc welding technique. In the present research, a comparative study of Stellite 21 weld overlays deposited in three different thicknesses, i.e. dilutions, at various preheat and post-weld heat treatment temperatures on the surface of AISI 410 martensitic stainless steel, has been made. The surface of coatings has been examined to reveal their microstructures, phase characterisation and mechanical properties using XRD, microhardness tester and metallographic techniques. The results showed that the deposition of Stellite 21 coating on AISI 410 martensitic stainless steel improved its corrosion resistance. Moreover, the volumetric dilution had a considerable effect on the hardness, microstructure and electrochemical corrosion behaviour of Stellite 21 weld overlays.     

Facile Plasma‐Enhanced Deposition of Ultrathin Crosslinked Amino Acid Films for Conformal Biometallization

A novel method for the facile fabrication of conformal, ultrathin, and uniform synthetic amino acid coatings on a variety of practical surfaces by plasma‐enhanced chemical vapor deposition is introduced. Tyrosine, which is utilized as an agent to reduce gold nanoparticles from solution, is sublimed into the plasma field and directly deposited on a variety of substrates to form a homogeneous, conformal, and robust polyamino acid coating in a one‐step, solvent‐free process. This approach is applicable to many practical surfaces and allows surface‐induced biometallization while avoiding multiple wet‐chemistry treatments that can damage many soft materials. Moreover, by placing a mask over the substrate during deposition, the tyrosine coating can be micropatterned. Upon its exposure to a solution of gold chloride, a network of gold nanoparticles forms on the surface, replicating the initial micropattern. This method of templated biometallization is adaptable to a variety of practical inorganic and organic substrates, such as silicon, glass, nitrocellulose, polystyrene, polydimethylsiloxane, polytetrafluoroethylene, polyethylene, and woven silk fibers. No special pretreatment is necessary, and the technique results in a rapid, conformal amino acid coating that can be utilized for further biometallization.     

Gold electrodes from recordable CDs

Gold electrodes are widely used in electrochemistry and electroanalytical chemistry. The notable performance when used in stripping analysis of many ionic species and the extraordinary affinity of thio compounds for its surface make these electrodes very suitable for many applications. This paper reports a simple and novel way to construct gold electrodes (CDtrodes) using recordable CDs as the gold source. The nanometer thickness of the gold layer of recordable disks (50-100 nm) favors the construction of band nanoelectrodes with areas as small as 10(-6) cm2. The plane surface can be easily used for the construction of conventional-sized gold electrodes for batch or flow injection analysis or even to obtain electrodes as large as 100 cm2. The low price of commercial recordable CDs allows a "one way use". The evaluation and applicability of these electrodes in the form of nanoelectrodes, in batch and associated with flow cells, are illustrated in this paper.     

The observation of unipolar arc damage on stainless steel and TiC coatings on stainless steel

Unipolar arcing represents a plasma-surface interaction process leading to surface damage and metal impurity influx in tokamaks. It develops if the sheath potential formed in the plasma-surface contact is high enough to ignite and sustain a micro-arc. A laser-produced plasma was used for a comparison of the arc damage produced on stainless steel surfaces with that on surfaces protected with a coating of TiC a few microns thick. Smooth coatings of superior-quality TiC were produced by the activated reactive evaporation process, which is a plasma-assisted physical vapor deposition process. For a sufficiently high electron temperature in the laser-produced plasma a large number (about 300 000 cm^?2) of unipolar arc craters were observed on the stainless steel surface which had been exposed to the expanding laser-produced plasma cloud for a few hundred nanoseconds. In comparison, no similar arc craters were detected on the surfaces protected by the TiC coating which showed minimum damage limited to the laser beam impact area.     

Titanium nitride film as a protective coating for a vacuum deposition chamber

A hard and anti-corrosive titanium nitride coating is proposed for use as a permanent coating layer on the inside walls of vacuum chambers and tooling that are exposed to repeated depositions of soft metals. Excellent characteristics for the removal of deposited aluminum or copper by either chemical cleaning or glass bead blasting are demonstrated. The completion of removal can easily be monitored by the obvious gold color of the coating layer.The outgassing rate at room temperature is considerably lower than that of bare stainless steel plate. Characterization of the titanium nitride layer is made by X-ray diffraction, Auger electron spectroscopy, electron spectroscopy for chemical analysis, and secondary ion mass spectrometry.     

Surface hardness improvement of plasma-sprayed AISI 316L stainless steel coating by low-temperature plasma carburizing

Low-temperature carburizing below 773 K of austenite stainless steel can produce expanded austenite, known as S-phase, where surface hardness is improved while corrosion resistance is retained. Plasma-sprayed austenitic AISI 316L stainless steel coatings were carburized at low temperatures to enhance wear resistance. Because the sprayed AISI 316L coatings include oxide layers synthesized in the air during the plasma spraying process, the oxide layers may restrict carbon diffusion. We found that the carbon content of the sprayed AISI 316L coatings by low-temperature carburizing was less than that of the AISI 316L steel plates; however, there was little difference in the thickness of the carburized layers. The Vickers hardness of the carburized AISI 316L spray coating was above 1000 HV and the amount of specific wear by dry sliding wear was improved by two orders of magnitude. We conclude that low-temperature plasma carburizing enabling the sprayed coatings to enhance the wear resistance to the level of carburized AISI 316L stainless steel plates. As for corrosion resistance in a 3.5 mass% NaCl solution, the carburized AISI 316L spray coating was slightly inferior to the as-sprayed AISI 316L coating.     

pH值对Cu-Co合金镀层结构及中温氧化行为的影响

为探索适合用作铁素体不锈钢表面的保护涂层,在不同pH值条件下,通过电沉积法在SUS430铁素体不锈钢表面共沉积Cu-Co合金镀层,并在750℃下进行中温氧化试验,利用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)等手段,分析镀层及氧化膜的形貌和组成,结合增重法研究Cu-Co合金镀层的中温抗氧化性能。结果表明:随着pH值的增加,镀层中Co元素的含量逐渐增大,Cu元素含量逐渐减小;在750℃中温氧化时,pH=6试样氧化速率最小;经400 h氧化后,基体表面的氧化物为Cr_2O_3和Fe_3O_4,pH=4镀层的氧化物主要为CuO,pH=5镀层的氧化物开始形成(Cu,Co)_3O_4尖晶石氧化物,pH=6镀层的氧化物中(Cu,Co)_3O_4和CuO成为主相;随着氧化时间的延长,pH=4,5镀层的氧化物晶粒缓慢长大,pH=6镀层的氧化物颗粒逐步细化;Cu-Co合金镀层氧化后的氧化层与SUS430钢的热匹配性较好,且镀层中Co含量较高时,其抗氧化性也较好,因此,pH=6镀液中获得的合金镀层适合用作铁素体不锈钢表面保护涂层。     

超级铁素体不锈钢表面超疏水结构的制备及其耐腐蚀性能

将多巴胺的自发聚合反应与低表面能物质ODA和PFDT结合,在超级铁素体不锈钢表面制备了均匀致密的超疏水薄膜.用水雾凝聚实验、扫描电子显微镜(SEM)和X射线能谱分析(EDS)等手段表征了涂层修饰前后的润湿性、表面形貌以及化学结构,并使用三电极体系电化学工作站测试了超级铁素体不锈钢表面修饰前后涂层的阻抗谱和极化曲线.结果...