Showing papers in "Materials protection in 2006"

Effect of Plasma Enhanced Chemical Vapor Deposition Parameters on Characteristics of Silicon nitride Film

Abstract: A double-deck plasma enhanced chemical vapor deposition (PECVD) facility was used to prepare silicon nitride film on the finely polished (100) plane of p-type single crystal silicon wafer. The effect of the deposition parameters on the characteristics of the silicon nitride film was investigated, while the optimized deposition condition was established. It was found that the optimal temperature for the silicon wafer substrate was 300 ℃. The silicon nitride film deposited at this temperature and a gas flux ratio of SiH_ 4 /NH_ 3 =1:10 had the highest refractive index and best uniformity, while the film of a Si/N ratio near to chemical computation 0.75 had excellent electronic and passivation properties.

Recent Progress in Anti-Icing Coating for Transmission Line

Abstract: Icing disaster of transmission line and its prevention has become an important and hot problem. Research and development in the field were summarized. By comparing the advantage and disadvantage of various anti-icing techniques, research and development of anti-icing coating were proposed. The requirement and prospect for the coating were also discussed.

Effect of Chlorine Ions on the Corrosion Behavior of Reinforcing Steel in Concrete

Abstract: A review was given to summarize the effect of chlorine ions on the corrosion behavior of reinforcing steel in concrete and the progress of the related research.Thus the corrosion behavior of the reinforcing steel,the deactivation mechanism of chlorine ions,the source of the chlorine ions in the concrete,the measures to protect the reinforcing steel,and the related research progress were highlighted.It was pointed out that the corrosion of the reinforcing steel in concrete was mainly attributed to chlorides,since the chlorine ions are able to destroy the passive film,induce localized corrosion of the reinforcing steel,and catalyze the corrosion process.However,the chlorides would not lead to corrosion of the reinforcing steel unless their concentration rose to a certain threshold value.Unfortunately,no widely acceptable threshold concentration of the chlorine ions causing the corrosion of the reinforcing steel is available so far,which is largely attributed to its dependence on various factors.

Effect of Magnetron Sputtered Coatings on Corrosion Behavior of Gd in Water

Abstract: Rare earth Gd is liable to corrosion in water used as the heat exchanging liquid of magnetic refrigerator, which leads to worsening in the performance of the Gd as a magnetic refrigeration material. Thus the coatings of Ti and 1Cr18Ni9Ti stainless steel were prepared on the surface of Gd by means of magnetron sputtering so as to improve its corrosion resistance. The corrosion behavior of the two types of magnetron sputtered coatings in deionized water and distilled water was evaluated. It was found that the Ti coating had obvious protection to Gd as the magnetic refrigeration material in terms of the corrosion in water, but the stainless steel coating had no protection to Gd. Moreover, Gd and Gd coated with the magnetron sputtered coating were more liable to corrosion in deionized water than in distilled water.

Simultaneous Determination of Cobalt and Nickel in Tin-Nickel Alloy Electroplating Solution by Two-Wavelength Spectrophotometry

Abstract: The Co~(2+) and Ni~(2+) in Sn-Ni environmentally acceptable electroplating solution were simultaneously determined by means of two-wavelength spectrophotometry,using 5-Br-PADAP of a concentration(002)% as the color-displaying agent and tween-80 of a concentration 1% as the dissolution-promoting agent in acetic acid-sodium acetate medium of a pH value 45It was found that the Bill's Law was valid when the concentration of Co~(2+) and Ni~(2+) was ranged within 0～6 μg/25 mLThe method could be readily used to determine the content of Co~(2+) and Ni~(2+) in the electroplating solution with expeditiousness and good accuracy

Corrosion Resistance of Magnesium Alloy with Complex Surface-Modifying Micro-Arc Oxidation Coating and Organic Coating Studied by Neutral Salt Spraying

Abstract: Magnesium alloy AZ91D was surface-modified by micro-arc oxidation (MAO). Several organic coatings were then prepared on the micro-arc oxidation coating of the Mg alloy. The corrosion resistance of the dual-phase surface-modification coatings was evaluated using neutral salt spray test. It was found that the micro-arc oxidation coating in combination with organic coatings contributed to significantly increase the corrosion resistance of the Mg alloy, which could make it possible for the Mg alloy after the dualphase surface-modification to be used in severely corrosive working conditions. Specifically, the micro-arc oxidation coating combined with electrophoresis coating was the most effective in increasing the corrosion resistance of the Mg alloy. The reason could lie in that the micro-arc oxidation coating was able to refine the surface microstructure of the Mg alloy and hence considerably increase the adhesion strength of the organic coatings thereon.

Effect of Encapsulation of Aluminum Pigment Powders by In-Situ Polymerization of Acrylic Acid on Corrosion Resistance

Abstract: Aluminum pigment powders were encapsulated by in-situ polymerization of acrylic acid so as to improve the corrosion resistance. The resulting encapsulated samples were characterized by means of infrared spectroscopy, optical microscopy, scanning electron microscopy, and granularity analysis. The influence of the encapsulation extent on the corrosion resistance and luster of the aluminum pigment powders was investigated. It was found that the corrosion resistance of the aluminum pigment powders could be effectively improved by encapsulation with in-situ polymerization of acrylic acid. The optimum condition for the in-situ polymerization was determined as temperature of 98 ℃, time of 1.0 h, initiator amount of 1.0 g, and isopropanol amount of 2.0 g. In particular, the aluminum pigment powders with an encapsulation extent of 10% had good corrosion resistance and luster.

Electroless Copper Plating in the Presence of THPED and EDTA·2Na as the Dual-Chelating Agent

Abstract: N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine (THPED) and ethyl-diamine-tetra acetic acid (EDTA·2Na) dual-chelating-agent system was introduced to decrease the costs and increase the stability of the bath and quality of the plating for electroless copper plating.Thus a systematical investigation was carried out with respect to the technology and plating performance based on the THPED-EDTA·2Na dual-chelating agent system.The optimized plating technology was determined,while the morphologies of the resulting platings were observed using a scanning electron microscope.Results indicated that the plating rate firstly increased and then decreased with increasing concentration of EDTA·2Na,while it firstly decreased and then increased with increasing concentration of THPED.Moreover,the plating rate firstly increased and then decreased with increasing concentration of CuSO-4· 5H-2O and HCHO,while it increased with increasing the pH value and temperature of the plating bath.Besides,the additives including 2-MBT,2,2-dipyridyl and K-4Fe(CN)-6·3H-2O had great effects on the plating rate and surface qualities of the copper coating,so did the additive polyethyleneglycol-1000(PEG-1000),although it had little effect on the plating rate.The optimized bath for the electroless copper plating was suggested to be composed of 10.0 g/L THPED,8.7 g/L EDTA·2Na,16.0 mL/L HCHO,12.0 g/L CuSO-4 5·H-2O,40.0 mg/L K-4Fe(CN)-6·3H-2O,10.0 mg/L 2,2′-dipyridyl,1.0 g/L PEG-1000,0.5 mg/L 2-MBT; and the optimized plating parameters were suggested to be pH value 13.2 and bath temperature 50 ℃.The plating bath showed good stability at the optimized plating conditions and the plating rate in a duration of 30 min was as high as 4.05 μm/h.The resulting copper coating was smooth and bright,showing good surface quality.

Effect of SiO_2 Nanoparticles on Performance of Dacromet Coating

Abstract: Dacromet composite coating was prepared by introduction of SiO_2 nanoparticles as the reinforcing agent. The composition and microstructure of the composite coating were analyzed by means of scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The effect of SiO_2 nanoparticles on the hardness, scratch resistance, friction-reducing ability, and corrosion resistance of the dacromet coating was highlighted. It was found that the incorporation of SiO_2 nanoparticles led to improvement in the hardness, wear resistance, scratch resistance, and corrosion resistance of the coating, while the desired appearance and good water resistance and adhesion of the coating were retained.

Quantum Chemical Study of Benzotriazole and Its Carboxyl-Alkyl Esters Derivatives as Corrosion Inhibitors

Abstract: The inhibiting mechanism and the reactivity of benzotriazole (BTA) and a series of alkyl esters (methyl, butyl, hexyl, and octyl) of carboxyl-benzotriazole were studied using quantum chemical calculation. The reactivity of the compounds in neutral and acidic solutions were analyzed by taking into account the charge distribution and contribution of heteroatoms N and O to the highest occupied molecular orbit (HOMO) and Fukui indices, based on quantum chemical calculation at B3LYP level with the 6-31G* base sets. It was found that the corrosion inhibition efficiencies of the molecules linearly corresponded to the distribution coefficient and polarizability. The corrosion-inhibition behavior of BTA and its derivatives was closely related to their physico-chemical adsorption on the metal surface.

Progress in Electroplating of Copper from Sulfate Bath

Abstract: A review is given on the electrodepositing mechanism of copper from sulfate bath and on the microstructure of the copper coating, the effect of additives on the electroplating process, as well as the research progress concerning copper electrodepositing. It has been pointed out that, with the development of microelectronics, the electroplating of copper has been currently focused on, owing to its engineering significance. Moreover, the future aspects in the research of electroplating copper are suggested as well.

Effect of Average Electric Current Density on Deposition Rate and Appearance and Structure of Pulse Electrodeposited Fe Coating

Abstract: Iron coatings were prepared on steel and copper substrates using pulse electrodeposition technique. The influence of the average current density on the deposition rate and appearance, microhardness, and microstructure of the as-deposited Fe coating was investigated. As the results, the Fe coating had satisfactory appearance in the early stage of increasing of the average current density, but the appearance became poor with extended increasing of the current density. At the same time, the deposition rate of the iron coating increased with increasing current density and the best deposition efficiency was reached at a current density of 16 A/ dm 2. Moreover, the microhardness of the Fe coatings prepared at different deposition conditions was roughly characterized by Gaussian distribution, while the cubic crystal of the Fe coating had obvious preferred orientation.

Study of Adsorption of Cr(VI)-Containing Wastewater by Organobentonite

Abstract: Crude bentonite was organically modified using hexadecyltri-methylammonium bromide (CTMAB).The resulting modified organobentonite was used to adsorb Cr(Ⅵ)-containing wastewater under static conditions.The effects of the concentration of CTMAB,organobentonite dosage,pH value of wastewater,and stirring time on the removal rate of Cr(Ⅵ) ions were studied,while the optimized processing conditions for the treatment of Cr(Ⅵ)-containing wastewater by organobentonite were determined.Results showed that the modified organobentonite was capable of effectively adsorbing and removing Cr(Ⅵ) in the wastewater.The optimum technological conditions were suggested as pH value of wastewater 3.0 to 5.0,stirring time about 30 min,and organobentonite dosage 10 g/L.Moreover,it was feasible to remove the Cr(Ⅵ) ions in the wastewater containing about 35 mg/L Cr(Ⅵ) at a removal rate over 98.0%,using the optimized processing conditions.And the content of Cr(Ⅵ) ions in the resulting treated wastewater was less than 0.50 mg/L,qualified in terms of the relevant national discharge standard.

Dispersion Stability of Nanoparticles and Its Evaluation Methods

Abstract: The dispersion stability of nanoparticles and the methods to evaluate the dispersion stability were summarized.The stabilization mechanisms(including electrostatic stabilization,steric stabilization and e1ectrostatic stabilization) of nanoparticles and their influences were highlighted,based on investigation of the dispersion processes of nanoparticles in liquid medium.The four commonly used methods to evaluate the dispersion stability of nanoparticles were compared.It was pointed out that,in order to realize and maintain nano size effect,it is extremely important and imperative to keep good dispersion stability of nanoparticles.Moreover,a prospect was suggested concerning the development of the methods to evaluate the dispersion stability of nanopaticles.

Properties of Brush Plating Ni-P-Nano SiC Composite Coating

Abstract: Nanometer SiC/Ni-P composite coating was prepared by brush plating. The effects of nano SiC particles content on the microhardness and wear resistance of coating wear determined, and the strengthening mechanism of nano SiC composite coating and the strengthening behavior in the crystallization process of Ni-P alloy were discussed. The results indicate that the brush plating technology can improve the dispersion even of nano SiC and the property of composite coating to some extent. Adding nano SiC particles about 7~10 g/L as required into the Ni-P alloy plating solution, the nano SiC can act as hard particles to intensify the composite coating, and can make the grain size of Ni-P crystallization fining to strengthen further. The microhardness and wear resistance of composite coating are obviously increased.

Effect of Laser Phase-Transformation Hardening on Wear-Resistance of Rotary Joint Made of 35CrMo Alloy

Abstract: Orthogonal test was performed to determine the laser phase-transformation hardening process suitable for a rotary joint made of 35CrMo alloy,which was aiming at increasing the wear-resistance of the rotary joint.Thus the optimized processing parameters were established,while the effect of laser phase-transformation hardening on the hardness and wear-resistance of the rotary joint was examined.As the results,the optimized processing parameters including laser power,laser spot size(diameter),and scanning speed were determined to be 1 500 W,3.5 mm,and 20 mm/s,respectively,at which a satisfactory surface-modification was realized.Namely,the surface hardness of the 35CrMo alloy rotary joint after laser phase-transformation hardening was as much as 786 HV- 1 N ,which was higher by 30% than that of the same rotary joint after carburization hardening.At the same time,the wear-resistance of the 35CrMo rotary joint was doubled after laser phase-transformation hardening,and the residual stress was dominated by compressive one,which could well accommodate the working conditions of the rotary joint.

Investigation of Palladium-Free Activation Process for Electroless Nickel Plating of ABS Plastic

Abstract: A Pd-free activation process was established for electroless nickel plating of acrylonitrile butadiene styrene (ABS) plastic. The optimized activation bath was explored, while the optimized parameters for the electroless nickel plating of ABS plastic were determined making use of uniform-design method. The morphology, microstructure, and elemental composition of the Ni coating on the ABS plastic were analyzed by means of scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy. As the results, it was feasible to generate activated nickel cores on ABS plastic at ambient temperature using NaBH_4 as the reducing agent, which made it possible for the electroless Ni coating to form on the surface of ABS plastic in the presence of the activated Ni cores as the reactive centers. The plating bath had good stability and relatively fast plating rate, while the Ni coating was uniform and well bonded to the substrate. Thus the established Pd-free activation process could be well used for the electroless nickel plating of the ABS plastic.

Microstructure and Characterization of Thermally Sprayed Coatings——a Review

Abstract: A review was given for progress in the research of the microstructure and characterization method of thermally sprayed coatings. Thus the characteristics of pores, the measurement of the pore rate, and the method to characterize the pores of the thermally sprayed coatings were highlighted, while the research on the lamellar structure and inter-lamellar bonding of the thermally sprayed coatings was briefed. It was pointed out that the pores in the thermally sprayed coatings were dominated by two-dimensional structure. Therefore it would be imperative to take into account both the porosity rate and the lamellar microstructure in the investigation of the microstructure of the thermally sprayed coatings.

Method and Equipment for Prevention of Germ Corrosion of Oilfield Injection Water Pipeline

Abstract: In order to resolve the germ corrosion of water injection metallic pipelines in oilfield, a high-performance injection water sterilization equipment was designed making use of alternating-electromagnetic-field-based physical sterilization technology. The equipment was combined with chemical sterilization method and used for the sterilization of the oilfield injection water. The results showed that sulfate reduced bacteria (SRB) and rotten generated bacteria (RGB) could be efficiently sterilized without changing the characteristics such as mechanical impurity and oxygen content of the injection water, using the designed device at a power of 32 W. Furthermore, the number of SRB decreased from 106～107 cells/mL to 0～10 cells/mL when the equipment was combined with chemical method to treat the oilfield injection water.

Process of Coarsening Pretreatment of Epoxy-Resin Packaging Material for Electroless Copper Plating

Abstract: The optimized coarsening pretreatment process for electroless copper plating of epoxy resin packaging material was established Thus the morphology of the epoxy resin packaging material after coarsening pretreatment was observed using a scanning electron microscope, while its surface roughness and water contact angle were measured It was found that the surface of the epoxy resin packaging material could be well chemically coarsened by immersing in the mixed solution of 300 g/L CrO3 and 225 mL/L H2SO4 at 85℃ for 30 min The resulting electroless copper coating on the coarsened surface had an adhension to the substrate as much as 5B grade and good electromagnetic shielding performance as well

Determination of Trace Chromium (VI) in Electroplating Wastewater by Catalytic Decolorizing Spectrophotometry

Abstract: A new catalytic decolorizing spectrophotometric method was established for the determination of trace chromium (Ⅵ) in electroplating wastewater, which was based on the catalytic effect of trace chromium (Ⅵ) to the oxidative decoloration reaction of azocarmine B and hydrogen peroxide in aqueous H_ 2 SO_ 4 .It was found that trace Cr(Ⅵ) could be measured to a detection limit of 0.10 μg/L and within a linear range of 0~60 μg/L using the established method, and the relative standard deviation was less than 1.5%. The method had been successfully applied in field test for the determination of trace chromium (Ⅵ) in electroplating wastewater.

Review on Current State and Development of Thermally Sprayed Functional Gradient Coatings

Abstract: A review was given on the current state and development of thermally sprayed functional gradient coatings.Thus the technical features of various thermal spraying methods applicable to the preparation of functional gradient coatings were summarized,and the advantages and disadvantages of these methods were briefed.Moreover,the recent progress in reaction thermal spraying technique developed from the combination of self-propagation high-temperature synthetic technique and thermal spraying technique and applicable to preparation of functional gradient coatings was introduced.And some perspectives were suggested concerning the development of thermally sprayed functional gradient coatings as well.

Selection of Coatings for Surface Protection of Annealing Furnace Roller for Automobile Plate and Causes Leading to Accumulated Burl of the Coating

Abstract: The features of various coating materials applicable to surface protection of annealing furnace roller of automobile plates were introduced, while the principles for the selection of the sprayed coatings used for the annealing furnace roller of automobile plates were discussed in connection with filed test results. It was pointed out that more strict requirements had been seen with respect to the ability to resist accumulated burl of the coatings used for the surface protection of the annealing furnace of automobile plates. Thus it would be imperative to develop novel high-performance surface-protective coatings so as to meet the need for the advancement of the automobile industry.

Selection of Materials for Drilling Tools Used in Natural Gas Field of High Acidity

Abstract: A polymer drilling fluid containing high content of hydrogen sulfide was used as the corrosive medium to investigate the effects of temperature, flow velocity, pH value, and partial pressure ratio of CO_2 /H_2 S on the corrosion behavior of high strength drill pipe steel S135 and G105. The morphology and composition of the corrosion products were analyzed as well. It was found that the average corrosion rate of the two types of steel increased with increasing temperature of the corrosive medium, with the corrosion rate to decrease slightly within 60～80 ℃ and keep almost unchanged above 120 ℃. At the same time, the corrosion rate of the drill pipe steels had little to do with the flow rate but increased with decreasing pH value of the corrosive medium. Moreover, the partial pressure ratio of CO_2 /H_2 S had a slight effect on the corrosion behavior of the drill pipe steel. However, the two types of drill pipe steel showed a larger corrosion rate in gas phase than in liquid phase corrosive medium, which was contrary to what were observed in gas and liquid phases corrosion tests of conventional acidic drilling fluids. In addition, it was confirmed by sulfide stress corrosion test that the drill pipe steel of a higher strength had smaller critical stress, and the resistance of the drill pipe steel to sulfide attack was ranked as G105(C)G105(D)S135(B)S135(A). It was anticipated that the present research results could be used to guide the selection of materials for drilling tools used in natural gas field of high acidity.

Influence of Rare Earth Cerium on Properties of HSn70-1 Tin Brass Used for Condenser Tube

Abstract: Effect of rare earth (RE) cerium on the structure of alloy was analyzed, the performance of alloy containing Ce was investigated by tensile test, and the influences of Ce with different content on the corrosion resistance of alloy were studied by corrosion test and electrochemical test. It indicates that the structure of alloy is obviously improved with an amount of Ce and trace boron, and the ductility and corrosion resistance also increase. Cerium can produce tight protective coating on corrosion surface and so improve the corrosion resistance of alloy. But the excessive Ce often aggregates easily to produce the Ce-rich phase, which results in worse thermoplasticity of alloy and hard to process.

Factors Affecting the Codeposition of Particulates in Complex Electroplating

Abstract: A review was given on the factors affecting the codeposition of particulates in composite electroplating.Thus the actions of various factors in the electroplating process were analyzed, the codeposition mechanisms of the particulates and the metallic matrix were discussed,and the methods to get rid of agglomeration of nano-sized particulates in the plating bath were summarized.It was pointed out that the content of the particulates in the electroplated coatings has significant effects on the hardness,corrosion resistance and wear resistance of the composite coatings,while the co-deposition of the particulates and metallic matrix is dependent on many factors such as current density,the surface charge of the particulates,temperature,pH value,and the agitation mode.Meanwhile,a prospect was provided concerning the development trend of composite electroplating.

Thermal Shock Resistance of Plasma Sprayed Nanostructured ZrO_2 Thermal Barrier Coating

Abstract: Yttria stabilized nanostructured zirconia (YSZ) thermal barrier coating was produced using atmospheric plasma spraying. The microstructure, grain size, and phase composition of the resulting coating were analyzed by means of scanning electron microscopy and X-ray diffraction. The thermal shock resistance was evaluated. It was found that there existed a great deal of un-molten particulates of an average size 51.8 nm and many tiny pores of a diameter below 1 μm in the as-prepared YSZ thermal barrier coating. At the same time, the coating was composed of cubic and tetragonal phases of zirconia and had little penetration cracks, which were beneficial to improving the thermal shock resistance of the coating. Namely, no signs of peeling-off were observed in the YSZ thermal barrier coating, after it was heated and held there for 10 min and cooled in air for 5 min within room temperature to 1 000 ℃ for 800 thermal cycles.

Application of Microorganism Adsorbent in Treatment of Wastewater Containing Heavy Metal——a Review

Abstract: The current state and progress in the research of microorganism adsorbent was reviewed with respect to the source and species of the adsorbents, the mechanism for the microorganism adsorbing, the major factors influencing the microorganism adsorbing, and the technology for the immobilization of biomaterials The present difficulties in connection with the application of microorganism adsorbent in treatment of wastewater containing heavy metals and the future direction were discussed It was pointed out that the pollution by heavy metals is causing increased concern with growing modern industry, hence the microorganism adsorption technology characterized by low cost, good effectiveness, and absence of repeated pollution would find promising application in the treatment of wastewater containing heavy metals

Study of Quick Local Electrodeposition by Jet Plating

Abstract: As a new plating process developed in recent years, jet plating is superior to commonly used electroplating processes in some aspects Thus the jet plating of Watt Ni on a platform movable in 2-dimensions was studied The effects of jet speed, distance between anode and cathode, bath temperature, and voltage on the jet plaiting were investigated It was found that the coating with preset patterns could be readily deposited on the metal substrate at a jet speed of 03 m/s , bath voltage of 20 V, and distance between anode and cathode of 17 mm The resulting coating was even and had good adhesion to the metal substrate

Microstructure and Thermal-Shocking Resistance of Nanostructured Zirconia Coating Prepared by Solution Precursor Plasma Spraying

Abstract: Nanostructured zirconia thermal barrier coating was prepared using solution precursor plasma spraying process.The transformation and deposition process of the solution precursor in the plasma flame and on the substrate were primarily investigated.The effect of the size of the mist-like droplet on the microstructure and phase structure,in particular,of the nanometer zirconia coating was examined.At the same time,the thermal-shocking resistance of the nanostructured zirconia coating was also evaluated using cyclic thermal-shocking test.It was found that the microstructure and phase structure of the nanostructured zirconia coating were closely related to the solution precursor plasma spraying process,especially,to the size of the mist-like droplet.Moreover,the as-deposited nanostructrued zirconia coating had good thermal-shocking resistance.