oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Impedance measurements for electroless nickel plating process
Karthikeyan,S.; Srinivasan,K.N.; Vasudevan,T.; John,S.;
Portugaliae Electrochimica Acta , 2006,
Abstract: electroless nickel (en) process is the controlled auto catalytic reduction of nickel ions using suitable reducing agent such as sodium hypophosphite on certain catalytic surfaces, which results in the production of sound, coherent coatings for a number of applications. frequently the rate of deposition of en with hypophosphite as reducing agent is below 20 microns per hour. hence the deposition of the electroless nickel with hypophosphite solution in the presence of small concentration of thiourea and its derivatives as accelerators is investigated. the mechanism of accelerated deposition is studied by impedance measurements. the performance of various additives during the plating process is being evaluated by increased constant phase element (cpe) and decreased charge transfer resistance values. a model is proposed for the adsorptive behavior of additives.
Impedance measurements for electroless nickel plating process
S. Karthikeyan,K.N. Srinivasan,T. Vasudevan,S. John
Portugaliae Electrochimica Acta , 2006,
Abstract: Electroless nickel (EN) process is the controlled auto catalytic reduction of nickel ions using suitable reducing agent such as sodium hypophosphite on certain catalytic surfaces, which results in the production of sound, coherent coatings for a number of applications. Frequently the rate of deposition of EN with hypophosphite as reducing agent is below 20 microns per hour. Hence the deposition of the electroless nickel with hypophosphite solution in the presence of small concentration of thiourea and its derivatives as accelerators is investigated. The mechanism of accelerated deposition is studied by impedance measurements. The performance of various additives during the plating process is being evaluated by increased Constant Phase Element (CPE) and decreased charge transfer resistance values. A model is proposed for the adsorptive behavior of additives.
EFFECT OF PRE - ZINKING PROCESSES ON QUALITY OF ELECTROLESS NICKEL PLATING ON Si-CONTAINING Al-ALLOY
铝硅合金压铸件浸锌对化学镀Ni-P层的影响

HUANG Xiao-mei,LI Ning,JIANG Li-min,LI De-yu,
黄晓梅
,李宁,蒋丽敏,黎德育

腐蚀科学与防护技术 , 2006,
Abstract: This paper describes the effect of pre-zinking processes on the quality of electroless nickel(EN) plating on a silicon-containing Al-alloy,by analyzing micromorophology,composition,thickness and corrosion resistance of zincate deposit,and the micromorphology,component,phase constituent,porosity,corrosion resistance and adhesion of EN plating as well.The results showed that zinking deposit was an important bridge connecting Si-containing aluminum alloy and EN plating.It was concluded that if there came to be a thin,well-distributed zinc on Si-contained aluminum alloy,the sequent EN deposit would be thin with good adhesion and high anti-corrosion performance.
Study of electroless nickel plating on PerFactoryTM rapid prototype model  [PDF]
J.C. Rajaguru,C. Au, M. Duke
Journal of Achievements in Materials and Manufacturing Engineering , 2012,
Abstract: This paper presents an investigation of electroless nickel plating on PerFactoryTM rapid prototype model built on PerFactoryTM R05 material. PerFactoryTM R05 is acrylic based photo sensitive resin. It is a popular material in rapid prototyping using PerFactoryTM method which employs addictive manufacturing technique to build prototypes for visual inspection, assembly etc. Metallization of such a prototype can extend the application envelop of the rapid prototyping technique as they can be used in many functional applications. Unlike the electroless nickel plating on metal substrate, the process on acrylic resin substrate is not auto-catalytic. Hence, etching and activation are necessary for initiating the process. The final coating is then investigated using scanning electron microscope (SEM) together with energy dispersive spectroscopy (EDS) and x-ray diffraction (XRD) analysis to identify the morphology and structure of the coating. The SEM & EDS analysis on surface and chemical composition of model surface after each preliminary surface treatment are also presented. Finally the layer is tested on Vickers micro hardness tester.
ELECTROLESS NICKEL PLATING ON CHITOSAN-MODIFIED WOOD VENEER  [PDF]
Lijuan Wang,Haibing Liu
BioResources , 2011,
Abstract: An activation process involving chitosan was conducted to prepare electroless nickel plated wood veneers for electromagnetic interference (EMI) shielding. In this process Pd(Ⅱ) ions were chemically adsorbed on wood surface modified with chitosan. Then they were reduced and dipped into a plating bath in which Ni-P co-deposition was successfully initiated. The coatings were characterized by SEM-EDS and XRD. The metal deposition, surface resistivity, and electromagnetic shielding effectiveness were measured. The morphology of the coating observed by SEM was uniform, compact, and continuous. EDS results showed that the coating consists of 1.8 wt.% phosphorus and 98.2 wt.% nickel. XRD analysis indicated that the coating was crystalline, which is supposed to be related to the low phosphorus content. The plated birch veneers exhibited electro-conductivity with surface resistivity of 0.24 Ω cm-2 and good electromagnetic shielding effectiveness of over 50 dB in frequency range from10 MHz to 1.5 GHz.
ELECTROLESS NICKEL PLATING BY INDUCED PHOTOSENSITIZER
光敏剂诱导化学镀镍的研究

YANG Yuguo,SUN Dongbai,YANG Dejun,
杨玉国
,孙冬柏,杨德钧

腐蚀科学与防护技术 , 1998,
Abstract: Electroless nickel plating can be conducted at room temperature in solutions containing dye as photosensitizer under illumination . Effects of intensity and wavelength of incident light, concentration of photosensitizer, nickel ion and hypophosphite on the deposition rate were studied. The morphology of the deposit was different from that of deposits obtained at high temperatures without the photosensitizer. According to the results, the reaction mechanism is proposed.
ADSORPTION PROPERTIES OF NICKEL-BASED MAGNETIC ACTIVATED CARBON PREPARED BY PD-FREE ELECTROLESS PLATING
Boyang Jia,Ling Su,Guangqian Han,Guangping Wang
BioResources , 2011,
Abstract: Nickel-based magnetic activated carbon was synthesized from coconut shell activated carbon by electroless plating with palladium-free activation. The effect of plating solution volume on metallic ratio and adsorption capacity were evaluated. The effect of metallic ratio on specific area, pore volume, and magnetic properties were investigated. The morphologies of activated carbon before and after plating were observed by SEM, and the composition of the layer was analyzed by EDS analysis. The results showed that the metallic ratio was increased with the increase of the plating solution volume. The magnetic activated carbon showed high adsorption capacity for methylene blue and a high iodine number. Those values reached 142.5 mg/g and 1035 mg/g, respectively. The specific area and pore volume decreased from 943 m2/g to 859 m2/g and 0.462 ml/g to 0.417 ml/g, respectively. And the layer was more compact and continuous when the metallic ratio reached 16.37 wt.%. In the layer, there was about 97 wt.% nickel and 3 wt.% phosphorus, which indicates that the layer was a low-phosphorus one. At the same time, magnetism was enhanced, making the product suitable for some special applications.
Effects of Hard Surface Grinding and Activation on Electroless-Nickel Plating on Cast Aluminium Alloy Substrates  [PDF]
Olawale Olarewaju Ajibola,Daniel T. Oloruntoba,Benjamin O. Adewuyi
Journal of Coatings , 2014, DOI: 10.1155/2014/841619
Abstract: This work examined effects of hard surface polishing grits and activation on electroless-nickel (EN) plating on cast aluminium alloy substrates in sodium hypophosphite baths. As-received aluminium alloy sample sourced from automobile hydraulic brake master cylinder piston was melted in electric furnace and sand cast into rod. The cast samples were polished using different grits (60?μm–1200?μm) before plating. The effects on adhesion, appearance, and quantity of EN deposits on substrates were studied. Observation shows that the quantity of EN deposit is partly dependent on the alloy type and roughness of the surface of the substrates, whereas the adhesion and brightness are not solely controlled by the degree of surface polishing. The best yield in terms of adhesion and appearance was obtained from the activation in zincate and palladium chloride solutions. Higher plating rates (g/mm2/min) of , , and were obtained from chromate, zincate, and chloride than , , and as obtained from HCl etched, NaOH, and H2O activated surfaces, respectively. 1. Introduction Al alloys are widely used in engineering structures and components where light weight or corrosion resistance is required [1] such as automotive engines. Aluminium-magnesium alloys are found useful in automotive engine cylinder, master brake, and clutch cylinder and so on, but they are subject to wear and corrosion. Ajibola and Jimoh [2] and Ajibola et al. [3] had studied the quality, while Ajibola et al. [4] studied the wear behaviour of Al alloys used in making brake master cylinder pistons used hydraulic brake fluid. The studies were performed to assess the metallurgical properties and wear rates of pistons with the view to improving on the wear resistance and corrosion resistance of the Al alloy substrates in brake fluid. The studies [4, 5] also suggested the application of surface treatment and overlay of durable metallic film as remedy to alleviating wear and corrosion of this useful machine part in brake oil. There are various methods of metal coating. These include processes like hot dipping, anodising, electroplating [6–8], electroless-plating [9–13], autocatalytic plating [13], cladding, Parkerizing, and galvanising. Plating has been done for hundreds of years, but it is also critical for modern technology. Plating is used for decoration, corrosion inhibition, to improve solderability, to increase hardness, to improve wear resistance, to reduce friction, to improve paint adhesion, and to alter conductivity, for radiation shielding, and for other purposes. Electroless-nickel (EN) plating is a
Electroless Plating of Nickel on Magnesium Alloy AZ91D with Pre-phosphorization
镁合金化学转化膜上化学镀镍的研究

CUI Zuo-xing,GU Yun-fei,SHAO Zhong-cai,WEI Shou-qiang,TIAN Yan-wenSchool of Materials & Metallurgy,Northeastern University,Shenyang,School of Environment,Chemical Engineering,Shenyang Ligong University,Shenyang,
崔作兴
,顾云飞,邵忠财,魏守强,田彦文

腐蚀科学与防护技术 , 2010,
Abstract: In order to enhance the anti-corrosion performance of AZ91D magnesium alloy,a composite coating cosisted of pre-phosphorization and electroless plating of nickel was investigated in detail.Firstly,the chemical conversion coating on AZ91D magnesium alloy was obtained in phosphate-permanganate solutions,and then electroless nickel plating was carried out on the conversion coatings.The surface morphology,phase constituents of the conversion coatings and the plated Ni-coatings were examined by scanning electron...
Fundamental Study of the Influence of Electroless Nickel Plating on PTC Effect in BaTiO3-based Ceramics
化学镀镍对BaTiO3基陶瓷PTC效应影响的机理研究

CHEN Wangping,LI Longtu,GUI Zhilun,QI Jianquan,WANG Dejun,
陈万平
,李龙土,桂治轮,齐建全,王德君

无机材料学报 , 1997,
Abstract: A fundamental study of the influence of electroless nickel plating on PTC effect in some semi-conducting ceramics of (Ba1-xPbx)TiO3 was made by comparison experiment. It was discovered that in some dense PTC ceramics the influence of nickel plating was not due to the permeation of plating solution into the ceramics, but was related to the reactions in the course of nickel plating.It was first proposed in this paper that nascent hydrogen generated in nickel plating could have infiuence on PTC effect.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.