CoCr-sputtering in large scale roll coating systems

CoCr-layers have been DC-magnetron sputtered onto Polyimide web in a 2 side sputter roll coater for 1.2 m web width. Magnetic as well as crystallographic properties have been investigated as function of the deposition parameters: layer thickness, coating drum temperature, background pressure and angle of incidence. First measurements of electro-magnetic properties also have been made. The influence of different protective layers on the lifetime of a CoCr floppy disk has been checked in first experiments.     

Oil presence in an evaporator: experimental validation of a refrigerant/oil mixture enthalpy calculation model

In this paper, the impact of the oil presence on the performances of a refrigerating machine is investigated both experimentally and numerically. To highlight the effect of oil, particularly on the evaporator behaviour, a theoretical model of enthalpy calculation for a refrigerant/oil mixture has been previously developed [Int J Refrigeration, 26(2003), 284]. In order to validate this model, tests were carried out on an industrial refrigerating machine working with R-407C. The lubricant is a polyol-ester oil whose solubility curves are given by the oil manufacturer. The oil circulating mass fraction is measured by a sampling technique and by an on-line density measurement method, whose advantages and drawbacks are presented. Both the model and the experiments show that the ratio of enthalpy change through the evaporator with to without the oil presence increases when the apparent superheat at the evaporator outlet increases. This is due to the presence of a non-evaporated amount of liquid refrigerant dissolved in the oil at this location, which is confirmed by visual observations. The numerical and experimental results are found to be in a good agreement as the maximum deviation is about 2.2%.     

高硅钢用半有机绝缘涂层的制备及其性能研究

为减少高硅钢铁芯叠片间的涡流损耗,以磷酸二氢铝、苯丙乳液、甘油及水为主要原料,制备出一种适合高硅钢用无铬环保半有机绝缘涂层.利用光电子谱仪、扫描电镜及能谱仪对高硅钢脱碳退火板的氧化薄膜、绝缘涂层的微观结构形貌及部分缺陷进行分析,并研究了该涂层的涂覆量对其附着性、硬度及绝缘性能的影响.研究结果表明:普通无取向硅钢磷酸盐环保半有机绝缘涂层同样适用于高硅钢;绝缘涂层的均匀性取决于高硅钢片表面的平整度、涂辊表面质量以及对涂覆速度的平稳控制;高硅钢的表面粗糙度及氧化膜厚度对绝缘涂层的附着性有着重要影响;本试验制备的半有机涂层每面涂覆量控制在0.8~1.2 g/m2,具有良好的附着性及绝缘性能,层间电阻在5Ω·cm2/片以上.     

Vacuum deposited polymer/metal multilayer films for optical application

Vacuum-deposited polymer/silver/polymer reflectors and tantalum/polymer/aluminum Fabry-Perot interference filters were fabricated in a vacuum web coating operation on polyester substrates with a new, high-speed deposition process. Reflectivities were measured in the wavelength range from 0.3 μm to 0.8 μm. This new vacuum processing technique has been shown to be capable of deposition line speeds in excess of 500 linear m min⁻¹ (D.G. Shaw and M.G. Langlois, Proc. 7th Int. Conf. Vacuum Web Coating, November 1993, p. 268). Central to this technique is a new vacuum deposition process for the high-rate deposition of polymer films. This polymer process involves the flash evaporation of an acrylic monomer onto a moving substrate. The monomer is subsequently cured by an electron beam or ultraviolet light. This high-speed polymer film deposition process has been named the polymer multi-layer process. Also, vacuum-deposited, index-matched, polymer/CaF₂ composites were fabricated from monomer slurries that were subsequently cured with ultraviolet light. This second technique is called the liquid multi-layer process. Each of these polymer processes is compatible with each other and with conventional vacuum deposition processes such as sputtering or evaporation.     

COATING THICKNESS EFFECTS ON THE LIFE OF TITANIUM NITRIDE PVD COATED TOOLS

The influence of coating thickness on the life time of titanium nitride (TiN) PVD coated high speed steel (HSS) cutting tools has been studied using planing and turning as machining test methods. The thickness of the coating was found to have a significant effect on tool life. In the planing tests a coating thickness of 2-3 μm was found to give the longest tool life. In the turning tests the tool life increased as the coating thickness increased, up to the maximum 6.0 μm thickness tested.

The chemical composition of the cutting fluid was also found to affect the tool life. The life of the coated tools was shorter in planing tests when using cutting fluids which contained EP (extreme pressure) -additives, sulfur additives showing shorter life than chloride.additives.     

刷镀铁工艺研究与应用

刷镀铁与刷镀镍相比具有成本低、硬度高的优点.研究了刷镀铁镀液中主盐、配位体、缓冲剂、抗氧化剂、表面活性剂等添加剂的种类、浓度及电压、pH值、阳极等工艺条件对镀层性能的影响,确定了镀液配方和工艺.结果表明,在优化的镀液配方及工艺条件下,可获得了良好的镀铁层,镀层硬度为450～500 HV.采用铁屑和三氯化铁配制镀液,成本低、配制速度快、浓度易控制、对环境无污染、所得镀层硬度高、结合力好.     

钢轨闪光焊接后轨腰原始裂纹的特征

在U75V钢轨的端部轨腰处采用线切割和高频疲劳预制轨腰裂纹,并进行闪光焊接,在放置7a（天）后对焊接接头试样的裂纹表面形貌和脱碳现象进行了分析和研究。研究表明,预制轨腰裂纹与其他轨腰焊接水平裂纹的宏观和微观区别,为今后焊接接头处的轨腰水平裂纹质量检验和判断提供了依据。     

A 0.2 msec Xenon Strobe Lamp for Flash-Photomicrography

As an illuminant for photomicrography Electronic flash has much to offer and is becoming increasingly popular in this field due to its many advantages over thermal type sources. A few commerically available flash-sources are available for this work but are, in general, restricted for use with a given microscope and are of limited application. The unit described is designed to provide for a wide range of work with any free standing microscope and can offer a choice of outputs according to the nature of the task in hand. Whereas most designs incorporate a secondary, thermal, source for lining-up and observation this has not been necessary here due to the employment of a strobe tube providing a 50Hz flicker free continuum which, on command, can be instantly switched to provide a high energy flash for exposure. Apart from the well known advantages such as daylight spectral quality (c.6000°K) and a comparative freedom from heat, the short duration exposure (0.2ms) is highly suitable for arresting motile specimens such as protozoa. Free from such problems as thermal inertia and excessive heat the unit described is ideal for time-lapse Kine recording and its use can be further extended to include flash-fluorescence photomicrography due to the high Ultra-Violet emission from the quartz envelope of the lamp.     

Impact of refrigerant–oil solubility on an evaporator performances working with R-407C

We propose in this study a simplified model of enthalpy calculation for a refrigerant–oil mixture, as well as a new presentation of the pressure–enthalpy–vapour quality diagram which is applied to refrigerant–oil mixtures with different oil circulating mass fractions. This presentation allows the calculation of the enthalpy change through an evaporator, with and without taking into account the effect of oil, and the prediction of the non evaporated quantity of refrigerant at the compressor suction. The results of the model for two pairs of R407C/POE oil of different solubilities show that under the same working conditions, the solubility of the refrigerant in oil can have a considerable effect on the evaporator performances. Indeed, for two oils presenting the same viscosity grade, the evaporator performances decrease when the refrigerant–oil solubility increases.     

Electron Beam Bias for Thin Capacitor Web Coating

Electron beam induced bias was applied for high speed, high quality coating of ultra thin capacitor web. Electron beam charging applies a static charge to the film and allows higher bias voltages than conventional bias systems. Using a numerical calculation of the electrical and thermal forces at work it can be shown that electron beam bias results in better cooling and lower peak temperatures of the film. The advantages for the film coating process are higher possible coating speeds and/or better film quality. Further, the effect of pinholes during coating is much reduced.     

Silicon made resonant microcantilever: Dependence of the chemical sensing performances on the sensitive coating thickness

A gas sensor based on the use of a resonating microcantilever has been realized by using a polymer sensitive coating. From the theoretical study of the microcantilever sensitivity, it has been deduced that the sensitivity is enhanced when the resonant frequency or the sensitive coating thickness are increased. The sensitive coating thickness influence has then been verified experimentally by using polyetherurethane (PEUT) as sensitive coating for ethanol detection. From these measurements, some drawbacks are shown: the coating thickness increase leads to a sensor response time increase and a frequency noise increase which worsens the limit of detection. Conclusions are then made about the sensitive coating optimization depending on application constraint considerations.     

Design of metallization equipment for web coating

As a result of the increasing demands created by the wide range of such applications as decorative, packaging, energy conservation and electronic materials, the continuous web metallizing process has become sophisticated and exacting. High system reliability and precise quality control are required to achieve the continuous deposition of thin metallic coatings onto polyester films, paper and cloth in roll form. An in-depth discussion of the critical areas in the design and operation of equipment, together with the various deposition processes, is presented, with emphasis on the significance of vacuum level, uniformity of coating thickness and web transport properties, such as tension and temperature control.     

Residual stress, Young''s modulus and fracture stress of hot flame deposited diamond

Chemical vapour deposition (CVD) diamond coatings deposited on various substrates usually contain residual stresses. Since the residual stress affects the adhesion of the coating to the substrate, as well as the performance of the coating/substrate composite in many technical applications it is of importance to study the magnitude of these stresses.

In the present study the hot flame method was used to deposit diamond coatings on cemented carbide inserts by scanning the surface with a nine flame nozzle. By varying the oxygen to acetylene flow ratio and the deposition time coatings of different qualities and thicknesses were obtained. The residual strain/stress of the coatings was measured by three different methods: X-ray diffraction using the sin² (Ψ) method, Raman spectroscopy and disc deflection measurements. To extract the residual stress from the strain data the Young's modulus was obtained from bending tests of diamond cantilever beams manufactured from free standing diamond films. The latter technique was also used to determine the fracture stress of the diamond films.

All deposited coatings displayed a residual compressive strain/stress state. The residual strain in the diamond coatings did not vary with coating thickness (1.5 μm to 20 μm) but was found to increase from −1.8 × 10⁻³ to −2.2 × 10⁻³ with decreasing diamond quality. The compressive residual stress was found to decrease from −2 GPa to −1.3 GPa with decreasing diamond quality. This is mainly due to a decrease in Young's modulus (from 1.1 TPa to 0.6 TPa) with decreasing diamond quality. Also the fracture stress was found to decrease (from 1.8 GPa to 0.8 GPa) with decreasing diamond quality. The three methods used for measuring the stress state in the coatings, X-ray diffraction, Raman spectroscopy and deflection measurement, all give the same result. The deflection technique has the advantage that no information about the elastic properties of the coating is needed, whereas Raman spectroscopy has the best lateral resolution (≈5 μm) and is the fastest method (≈5 min).     

AZ51镁合金交流微弧氧化膜层厚度的研究

在氢氧化钾和氟化钾组成的电解液中,采用交流微弧氧化处理技术对AZ51镁合金进行表面处理.研究了处理参数对陶瓷氧化膜层厚度的影响,确定了膜层的组织构成.结果表明:KOH浓度在300~400 g/L时,膜层厚度几乎随着KOH浓度的增加呈线性增长;KF浓度在400~1 000 g/L,膜层厚度增加最快;电压处于50~80 V时,能够促进膜层的快速生长;当电解液温度在20~70℃,随着电解液温度的升高,膜层厚度逐渐增加;膜层厚度随处理时间延长快速增长,超过100 s后趋于平缓.膜层主要由氟化镁和氧化镁组成,致密膜层的最大平均厚度约为30μm,膜层厚度超过30μm后,膜层将出现"沙化层".     

The Overcoat Oil Lubrication of Microarc Oxidation Coating on Al Alloy by Liquid Plasma Technique

Ceramic coatings were deposited on 2Al2 alloy with a 100 kW micro-arc oxidation equipment consisting of a potential adjustable ac power supply and alkali electrolyte. The structure of the micro-arc oxidiation coatings was examined using scanning electron microscopy and transmission electron microscopy. The tribological properties of the coatings sliding against steel under the drop and adsorption lubrication of liquid paraffin were evaluated with a Timken tester. The lower friction coefficient of 0.14 and longer wear life of 2450 m of overcoat were observed for the polished micro-arc oxidation coating of 180μm thick at a sliding speed 2. 50 m/s and load 1500 N. This is because the coating has an interlayer of suitable porosity and thickness, which helps to improve the deposition of lubricants and endure the higher load. In other words, the oil is able to adsorb in the porous holes of the overcoat and provided the lubrication of micro reservoir during friction, and the compact and relatively hard interlayer of oxidation coating is able to support heavy load and prevent the oil lubricating film from damage.     

Evaluation of different preparations of plasma-spray hydroxyapatite coating on titanium alloy and duplex stainless steel in the rabbit

Many variables are involved in hydroxyapatite coating of metals by plasma-spray techniques. The authors have investigated the biological response to some of the most relevant variables in a controlled in vivo trial. The bone response in the rabbit towards hydroxyapatite coated cylinders was studied keeping the following variables fixed: (a) crystallinity of coating (greater than 90% and between 70% and 60%); (b) thickness of coating (50 and 100 m); (c) metallic substrate (titanium alloy and duplex stainless stell). Analysis of the results highlights the importance of defining the crystallinity of the coating to forecast its in vivo behaviour: highly crystalline coating is more stable in time but can give rise to fragmented bulky particles; a less crystalline coating is subject to slow degradation in the long term but facilitates its substitution by newly formed bone. Furthermore, it has been found that no relevant differences can be ascribed to a variation in coating thickness between 50 and 100 m. It has, also, been observed that there are no differences when duplex stainless steel is used instead of titanium alloy as metallic substrate, confirming that bone responds primarily to the coating.     

On-line laser-induced breakdown spectroscopy determination of magnesium coating thickness on electrolytically galvanized steel in motion

The application of laser-induced breakdown spectroscopy (LIBS) for online analysis of novel Zn based alloy coatings during continuous production of galvannealed steel has been demonstrated. Field trials were carried out at the ThyssenKrupp Steel (TKS) pilot plant in Dortmund, Germany. For this purpose, a portable LIBS demonstrator was constructed and evaluated, based on a dual-pulse Q-switched Nd:YAG laser, operated at 1064 nm. This system was used to generate plasmas on the moving sample surface after the annealing process, in order to control on-line the thickness of Mg on electrolytically galvanized steel. For variable Mg thicknesses (depending on strip speed of the pilot line, 100-1200 nm), and for steel sheets with a predetermined and constant Zn thickness (of 2 or 9 μm), a satisfactory agreement between plant LIBS measurements and data from laboratory chemical analysis (dissolution of the metallic coating and subsequent inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis) of Mg coating thicknesses has been obtained. The effects of environmental conditions on field measurements (strip temperature, mechanical vibrations, moisture on surface, etc.) have been demonstrated to be negligible, whereas minimal damage (crater diameters less than 150 μm) to the sample surface was caused.     

Preparation of stable ultrahydrophobic and superoleophobic silica-based coating

Silica-Based coatings having excellent water- and oil-repellent properties and good weathering stability have been deposited onto glass surface by a simple one-step dip coating technique. To achieve ultra water repellency and super oil repellency, the chemical composition of SiO2 nanoparticle employed as surface roughness enhancer and trichloro(1H,1H,2H,2H-perfluorooctyl)silane employed as surface-energy reducing substance was varied. At the optimum synthesis condition, the coating exhibited very high contact angles of 173.2, 146.7 and 147.6 degrees for water, ethylene glycol and seed oil, respectively. The achievement of excellent water- and oil-repellency is also described based on the presence of air trapped in micropore of the coating in addition to its high surface roughness and low surface free energy. The coatings have good weathering stability based on natural and accelerated weathering tests indicating feasibility for practical use.     

超音速火焰喷涂硅酸盐玻璃涂层工艺研究

采用超音速火焰喷涂技术制备了硅酸盐玻璃涂层,通过扫描电镜、能谱、衍射和强度试验研究了涂层的组织特征、机械性能等.研究表明,制备玻璃涂层的最佳工艺为:粉末颗粒尺寸为25～50μm,氧气流量34～36m3/h,煤油流量13～14L/h,喷涂距离25cm;涂层组织较致密,玻璃涂层厚度可达到0.5mm以上;涂层基本呈非晶态,热喷涂后玻璃涂层冷却速度对涂层的析晶行为有一定影响;涂层与基体之间的结合形式为机械结合,涂层的内聚强度约为8MPa,其拉伸断裂形式为宏观脆性断裂,涂层具有一定硬度和抗冲击性能.     

Hochrateabscheidung mit einem Mikrowellenplasma

High rate deposition with a microwave plasma The development of a plasma technological process of a scratch protection coating on plastics, for example on polycarbonate (PC), has to meet the conditions of a large area and a high rate deposition. The article presents a plasma technological concept, based on the scalable microwave plasma principle of the Duo‐Plasmaline, which provides due to the high plasma density a very high stationary coating rate of at least 20 μm/min with a high coating quality. The deposited protection coatings achieve the scratch resistance of window glass.