Preparation of nanocrystalline SnO2 thin film coated Al2O3 ultrafine particles by fluidized chemical vapor deposition

Fluidized chemical vapor deposition (FCVD) technology was developed for coating SnO₂ thin film on Al₂O₃ ultrafine particles. TEM and HREM analysis found that SnO₂ films with different structures were deposited by controlling the coating temperature, reactant concentration, etc. Nanocrystalline SnO₂ film was coated at 573.15 K by gas phase reaction of SnCl₄ with H₂O. EPMA and EDS studies indicated that the distribution of SnO₂ inner and outer of the agglomerates was uniform. Nucleation and film deposition were coexisted mechanism during the FCVD coating process. The fraction of SnO₂ in the composite particles increased with increasing coating temperature, SnCl₄ concentration, and coating time. The mass fraction of SnO₂ in the composite particles increased strongly with the ratio of P_H2O and P_SnCl4 at low mole ratio of H₂O with SnCl₄, but increased little under the conditions of excess H₂O with respect to SnCl₄.     

纳米金刚石复合镀层制备工艺的研究

纳米金刚石复合镀层具有金刚石和纳米颗粒的双重特性,应用前景广阔.采用复合电镀法制备了Ni-纳米金刚石复合镀层,考察了阴极电流密度、镀液pH值以及搅拌强度对纳米复合镀层显微硬度的影响,并分析了Ni-纳米金刚石复合镀层的共沉积过程.结果表明,选择适当的共沉积工艺参数,可以制备出同底材结合牢固,金刚石微粒弥散较均匀的高硬度纳米复合镀层,基质Ni中金刚石粒子的含量与镀面的机械俘获粒子的能力有关.     

Effect of activators on the properties of nickel coated diamond composite powders

Nickel coated diamond composite powders were fabricated via a newly developed direct electrodeposition technique. The effects of activators on the coating of diamond were firstly investigated and diamond grinding wheels were then prepared from Ni-coated diamond composite powders with different activators. The microstructural characterizations of this composite powders were finally conducted by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction, and the mechanical and tribological properties of as-prepared diamond grinding wheels were also measured. There are changes in microstructures and properties of the composite powders with activators. The activator concentration also has an influence on the morphologies and phase structures of the Ni coating on diamond particles.The composite powders with more compact coating of nickel can be prepared by adding 1 g dm~(-3) or more AgNO_3 as an activator to electrodeposit nickel on diamond. The mechanical and tribological properties of diamond grinding wheels were significantly improved when the coating phase structure of Ni crystal grew with(111) plane orientation on the surface of diamond particles. The wheels made from nickel coated diamond composite powders possessed the advantages of easy preparation and outstanding tribological properties. Therefore, Ni coated diamond composite powders exhibit a great potential to be extensively applied in diamond cutting and grinding tools.     

电沉积参数对镍-纳米金刚石复合镀层性能的影响

目前有关纳米复合镀层电沉积的研究还不够深入、系统。以瓦特镀镍液为基础,在Q235A钢基体上制备镍-纳米金刚石复合镀层,研究了纳米金刚石浓度、搅拌速度对镍-纳米金刚石复合镀层性能的影响规律。在测试纳米金刚石复合镀液中镍的还原行为时发现,随着纳米金刚石浓度的升高,镍离子的极化程度呈现先升高后下降的趋势,镀液中纳米金刚石浓度为8.0 g/L时极化程度最大,同等条件下直流电沉积制备的复合镀层硬度、弹性模量分别为4.66 GPa和195.2 GPa,而双脉冲电沉积制备的镀层硬度和弹性模量分别达到5.23 GPa和197.4 GPa。     

Construction and characterization of a sputter deposition system for coating granular materials

In many modern ceramic or metal matrix composites the interface between the matrix and the reinforcements (particles or fibres) plays an important role. Either no or only weak mechanical bonding is observed or severe reactions between the matrix and the filler during the manufacturing process take place. A method to promote adhesion or to avoid severe reactions is to use coated reinforcements. A uniform film can act as an adhesion promoter, a compliant layer, a reaction inhibitor or a promoter of thermal transport across the interface.The aim of this work was to construct a particle coating system based on magnetron sputter deposition which allows to keep the particles or the granular material in motion during the deposition process to guarantee a homogenous coating on every single particle. As particles to be coated diamond granulates and carbon fibres were investigated. For transparent diamond particles the uniformity of a metallic coating could be evaluated by transmission optical methods and was found to be quite high. Carbon fibres, on the other hand, could only partially be coated due to agglomeration and shadowing effects. The system presented here can be considered as suitable for coating spherical or close to spherical granular matter.     

电子封装用Diamond/Cu复合材料的化学镀镍

通过采用在Diamond/Cu复合材料表面化学镀镍的方法来改善其焊接性.化学镀镍前,采用SnCl2溶液和PdCl2溶液对复合材料表面进行敏化、活化等预处理.研究了pH值和温度对化学镀镍沉积速度的影响.利用SEM、EDX、XRD和划痕实验等措施对镀层进行了研究,结果表明,在Diamond/Cu复合材料表面获得了均匀、致密...     

Diamond electroplated coating with protection by diamond micron powder in a dressing tool. Part 1. Coating deposition conditions

The authors put forward a method of protection of diamond electroplated coating in a dressing tool made by the electroforming process. The method consists in using diamond micron powder in the surface layer of the nickel bond in order to protect the bond surface against hydroabrasive wear. The paper provides a procedure of calculation of nickel (the basis for the diamond electroplated coating) deposition conditions, taking into account the change in the free surface area of deposition due to cross-sectional area of diamond grains of the working fraction and the micron powder. The procedure permits computing the refill-deposition rate and duration, the final thickness of the coating and its protective sublayer.     

金刚石薄膜中晶粒尺寸的研究

扫描电子显微研究表明，化学汽相沉积的金刚石薄膜中晶粒大小比较均匀。但随着沉积时间和薄膜厚度的增加，晶粒逐渐变大，且每一层内，存在少量的大金刚石颗粒，讨论了晶粒尺寸变化和大晶粒形成的原因和机制。     

Ni-Fe-P/金刚石复合电沉积层组织结构的研究

对Ni-Fe-P/Diamond复合电沉积层的组织结构进行了研究，沉积层X－射线衍射及环境扫描电镜与沉积层组织结构点，面成分能谱分析结果表明，在试验所进行的镀覆工艺控制范围内，可获得表面平整，光滑，金刚石微粒均匀分布且具有中度的非晶态复全电沉积层；共沉积在Ni-Fe-P合金中的金刚石微粒基本不影响基质合金组织结构的无序度；复合电沉积层中金刚石微粒按“阳离子吸会－包覆”机理共沉积入复合层中。     

等离子喷涂工艺对钽/钨复合涂层组织结构的影响

采用等离子喷涂方法制备了Ta/W复合涂层,研究了喷涂距离和喷涂功率对Ta/W涂层密度、沉积效率、化学成分和组织结构的影响.结果表明,Ta/W涂层组织致密,钽、钨涂层之间没有明显的界面,涂层密度分别达到14.27 g/mm3和16.86 g/mm3;喷涂功率对钨粉的沉积效率影响较大,喷涂功率低于40 kW以下时钨粉的沉积效率极低;涂层中的氧含量较低,氧化主要发生在熔融粒子飞行过程中,采用惰性气体保护可以减少涂层中的氧含量.     

Potentialunterstützte Herstellung von Metall‐Keramik‐Verbundschichten

Potential assisted fabrication of metal‐ceramic composite coatings A possibility to produce uniform metal‐ceramic composite coatings with a high content of ceramic particles up to 60 vol.% will be presented in this study. This method includes a combination of electrophoretic deposition and electrolytic deposition by several steps. A yttria‐stabilized zirconia coating (Tosoh TZ‐8Y) was first electrophoretically deposited on a ferritic steel plate and then sintered by 1100 °C to an open porous layer. In the next step nickel was electrodeposited into the pores of the layer. By a final annealing step it was possible to improve the bonding of the composit coating on the substrate by diffusion of the metal components.     

Diamond formation on carbon/carbon composite

A carbon/carbon composite was used as substrate for low-pressure diamond deposition. To enhanced diamond nucleation on carbon/carbon composites, a total of ten surface preparation methods have been investigated. These methods involved the use of atomic hydrogen etching, mechanical polishing, sonication, or coating. Diamond nucleation was found to occur on either the defects of the carbon/carbon composite substrates or diamond particulate left on the substrates. The defects were created primarily by atomic hydrogen etching during the coating process. Seeding with diamond powders was performed by dip coating, sonication, or spray-coating processes. It was found that these seeding processes resulted in excellent nucleation of diamond.     

纳米Ni60-TiB2复合涂层的超音速火焰喷涂制备及600℃循环氧化特性

采用超音速火焰喷涂技术在45#钢基体表面制备纳米Ni60-TiB2复合涂层,研究了纳米和常规微米Ni60-TiB2复合涂层在静态大气环境下600℃的循环氧化行为。结果表明：纳米Ni60-TiB2涂层具有晶粒纳米化和微观组织均匀化的特点,其氧化膜由完整连续SiO2膜构成,在其上均匀地分布着细小的TiO_2颗粒和B_2O_...     

Nanowhiskers formation by radio frequency Ar/O2 plasma etching of aluminum coated diamond films

Diamond nanowhiskers were fabricated by etching as-grown and aluminum coated diamond films in radio frequency (RF) Ar/O₂ plasma. It was found that diamond nanowhiskers could be obtained by anisotropic etching of both kinds of films. For the as-grown diamond film, the whiskers randomly formed on the diamond surface with higher etching rate. However, for the Al-coated diamond film, an energy dispersive X-ray spectroscopy measurement revealed that the distribution of the whiskers was the same as that of the coated Al particles. During the etching process, Al particles served as masks contributing to restraining the etching of the film underneath. It was found that the distribution of the whiskers was significantly influenced by the Al coating. The whiskers (1 μm in height and 50 nm in diameter) could be obtained under the optimum etching condition. In addition, the dependence of the distribution of the whiskers on Al coating time was demonstrated.     

Eigenschaften und Anwendungen von Chemisch Nickel‐Dispersionsschichten

Properties and applications of electroless nickel composite coatings This paper discusses the variety of composite electroless coatings used in different industrial applications. The inclusion of particulate matter within electroless nickel deposits can add entirely new properties to the plated layer. Composites with hard particles like diamond, silicon carbide and boron carbide provide greater wear resistance and the possibility for adjustable friction properties. Composite electroless nickel with diamond or ceramics has found wide applications in the textile, automotive and mechanical engineering industry. Friction joints in automotive engines constitute an important field of application for diamond coatings. Modern internal combustion engine designs require that the crankshaft and camshaft be fitted at a specific relative angle. In order to establish the correct angle during assembly and maintain it over the life of the engine, axial press‐fit joints in combination with centrally located retention bolts are employed. Failure of either the joints or the bolts can result in serious damage to the engine. The torque transfer ability of these engine components can be significantly increased by incorporating a friction foil that is diamond‐coated on both sides. Composite coatings with coarser diamond particles can be used for the coating of precision tools in the semiconductor industry. Enhanced lubricity can be achieved by incorporating solid lubricants in electroless nickel deposits. Composite coatings with PTFE or PFA offers non‐stick surfaces with antiadhesive properties and good resistance against adhesive wear. Because of the temperature and softness limitations these coatings are best suited for lower temperature and light loading applications. Electroless nickel boron nitride coatings can withstand temperatures up to 600 °C. This coating reduces coefficient of friction and wear in dynamic applications. A further application is the coating of molds for rubber and plastic components.     

Fabrication and Characterization of FeNiCr Matrix-TiC Composite for Polishing CVD Diamond Film

Dynamic friction polishing (DFP) is one of the most promising methods appropriate for polishing CVD diamond film with high efficiency and low cost.By this method CVD diamond film is polished through being simply pressed against a metal disc rotating at a high speed utilizing the thermochemical reaction occurring as a result of dynamic friction between them in the atmosphere.However, the relatively soft materials such as stainless steel, cast iron and nickel alloy widely used for polishing CVD diamond film are easy to wear and adhere to diamond film surface, which may further lead to low efficiency and poor polishing quality.In this paper, FeNiCr matrix-TiC composite used as grinding wheel for polishing CVD diamond film was obtained by combination of mechanical alloying (MA) and spark plasma sintering (SPS).The process of ball milling,composition, density, hardness, high-temperature oxidation resistance and wear resistance of the sintered piece were analyzed.The results show that TiC was introduced in MA-SPS process and had good combination with FeNiCr matrix and even distribution in the matrix.The density of composite can be improved by mechanical alloying.The FeNiCr matrix-TiC composite obtained at 1273 K was found to be superior to at 1173 K sintering in hardness, high-temperature oxidation resistance and wearability.These properties are more favorable than SUS304 for the preparation of high-performance grinding wheel for polishing CVD diamond film.     

预镀镍对化学镀Ni-P-PTFE复合涂层结构和性能的影响

本文研究了预镀镍过程中不同电流密度和不同沉积时间下形成的预镀镍层对Ni-PPTFE(Poly tetra fluoro ethylene)复合涂层的微观结构和力学性能的影响。首先对304不锈钢基体进行合理的前处理,然后在基体上闪镀一层镍,最后在基体上进行化学镀Ni-P-PTFE复合涂层。通过控制预镀镍过程中的电流密度和沉积时间,利用电子扫描显微镜(SEM)、X射线衍射仪(XRD)、纳米压痕仪、WS-2005涂层自动划痕仪、HSR-2M摩擦磨损试验机对复合涂层的微观结构和力学性能进行了表征。结果表明:不同电流密度和不同沉积时间下形成的预镀镍层对Ni-P-PTFE复合涂层的微观组织、涂层硬度、结合力和摩擦系数都具有较大的影响。当电流密度为3.3A/dm~2,沉积时间为6min时,NiP-PTFE复合涂层的综合性能最佳,复合涂层的表面光滑均匀,其硬度和结合强度分别达到3.874GPa和27.45N,表面摩擦系数为0.145。     

Diamond deposition on Mo with thermal stress buffer layer coated mild steel substrate by combustion flame CVD

In order to develop wear resistance diamond/molybdenum (Mo) hybrid coating process can be conducted in open air. Diamond deposition on the molybdenum with thermal stress buffer layer coated mild steel substrate by the combustion flame chemical vapor deposition (CFCVD) was carried out. As the thermal stress buffer layer, atmospheric plasma sprayed Mo/Fe mixture coating was deposited between Mo top coat and mild steel substrate. Consequently, crack generation and peeling off of the coating occurred due to thermal influences on the condition of Mo coated mild steel substrate in our previous study, diamond particles could be created on the Mo coating without fracture and peeling off. Besides, an additional Mo coating after diamond deposition increases the adhesion force between the diamond coating and the initial Mo coating. This encapsulation of the diamond particles between two Mo layers dramatically improves the resistance of the global coating making it strong enough to resist to the wearing test. These results demonstrate the high potential of thermal sprayed coating for the wear resistance improvement.     

Growth of diamond films on SiC, WC and cubic BN substrates

The growth morphology of diamond films grown on single crystals of SiC and on sintered WC and cubic BN (CBN) substrates by hot filament assisted chemical vapour deposition was examined using transmission electron microscopy and scanning electron microscopy. Diamond was found to have the form of particles on the substrates of SiC and WC in the initial stage of film growth. Both an amorphous layer and a directly bonded area were seen at the interface. Several orientation relationships, different from the cube/cube relation, were observed in these systems. On the other hand, in the case of diamond films on CBN substrates, the growth morphology of diamond was affected by the surface condition of the substrates. When CBN substrates were polished with a diamond paste before deposition, diamond grew in the form of particles. The growth morphology was changed by ion sputtering of the surface of the substrate from particle growth to uniform film growth. These results are discussed on the basis of lattice mismatch at the interface. This revised version was published online in November 2006 with corrections to the Cover Date.     

直流热阴极PCVD法间歇生长模式制备金刚石膜

采用直流热阴极PCVD(Plasma chemical vapor deposition)法间歇生长模式制备金刚石膜,通过加入周期性的刻蚀阶段清除金刚石膜在一定生长期中形成的石墨和非晶碳等杂质,实现了金刚石膜生长的质量调控。间歇式生长过程分为沉积阶段和刻蚀阶段,两个阶段交替进行。采用Raman光谱、SEM和XRD对所制金刚石膜的品质进行了表征,并与同样生长条件下连续生长模式制备的金刚石膜样品进行了比较。结果表明,当单个生长周期为30 min(沉积时间为20 min、刻蚀时间为10 min)时,直流热阴极PCVD法间歇生长模式制备的金刚石膜中的非金刚石相杂质含量低于连续间歇生长模式制备的金刚石膜。