Preparation and Characterization of Electroless Ni-P and Ni-P-Si3N4 Composite Coatings

Electroless nickel, alloy, composite and nano coatings – A critical review

Abstract: The development of metal deposition processes based on electroless nickel, alloy and composite coatings on various surfaces has witnessed a surge in interest among researchers, with many recent applications made possible from many excellent properties. In recent years, these coatings have shown promising corrosion and wear resistance properties and large number of newer developments became most important from macro to nano level applications. After a brief review of the fundamental aspects underlying the coating processes, this paper discusses in detail about different electroless nickel alloy, composite, nano plating, bath techniques, preparation, characterization, new depositing mechanism and their recent applications, including brief notes on difficult substrate and waste treatment for green environment. Emphasis will be onto their recent progress, which will be discussed in detail and critically reviewed.

Influence of particle size on the microstructure, hardness and corrosion resistance of electroless Ni–P–Al2O3 composite coatings

Abstract: High phosphorus electroless nickel bath has been used to prepare composite coatings containing alumina powders (50 nm, 0.3 μm and 1.0 μm). Deposits were characterized for its structure, morphology and hardness. Incorporation of particle has a marginal influence on the composition. More amount of particle incorporation and uniform distribution was found in composite coatings obtained with 1.0-μm (C3) alumina particles compared to 50-nm (C1) and 0.3-μm (C2) alumina particles. XRD results showed a broad peak of nickel and low intensity alumina peaks present in C3 composite coating in as-plated condition. A marginal improvement in hardness was noticed in as-plated composite coatings. A 15% increase in microhardness was observed in the heat-treated (400 °C for 1 h) composite coatings. Potentiodynamic polarization measurements made on these deposits in 3.5% sodium chloride solution showed that uniform corrosion occurred in C1 and C2 composite coatings whereas localized corrosion was observed in C3 composite coating.

The friction and wear of electroless Ni–P matrix with PTFE and/or SiC particles composite

Abstract: In this paper, the friction behaviour and wear mechanism of electroless Ni–P matrix with PTFE and/or SiC particles composite coating are investigated by virtue of ring-on-disk wear machine at a high load of 150 N. The worn surface, wear debris and the composition changes after wear were characterized using scanning electron microscopy (SEM) and energy-dispersive analysis of X-ray (EDAX). By comparison with Ni–P and Ni–P–SiC coatings, the results indicated that the combination of a PTFE-rich mechanical mixed layer (PRMML) formed on the worn surface and hard SiC were responsible for the good tribological properties of the hybrid Ni–P–PTFE–SiC composites at high load. After heat treatment at 400 °C for 1 h, the wear rate of Ni–P matrix composites decreased with corresponding increase in microhardness. During sliding, an obvious decrease in the temperature rise with PTFE addition was attributed to the good anti-friction of PTFE.

Electroless coated disks for high temperature applications and methods of making the same

Abstract: A disk for a hard disk drive is provided. The disk comprises a substrate comprising aluminum, and a coating layer disposed over the substrate. The coating layer comprises an alloy of Ni, X 1 and X 2 , wherein X 1 comprises one or more elements selected from the group consisting of Ag, Au, B, Cr, Cu, Ga, In, Mn, Mo, Nb, Pb, Sb, Se, Sn, Te, W, Zn and Zr, and wherein X 2 comprises either B or P, and wherein X 1 and X 2 do not comprise the same elements.

The tribological behaviour of electroless Ni–P–Gr–SiC composite

Abstract: The tribological behaviour and wear mechanism of Ni–P–Gr (graphite)–SiC (manufactured by electroless plating) is surveyed in this paper. The worn surface, wear debris and the compositional changes that take place during wear were characterized using scanning electron microscopy (SEM) and energy-dispersive analysis of X-ray (EDAX). By comparison with Ni–P–Gr and Ni–P–SiC, the results indicate that hybrid Ni–P–Gr–SiC composite presented well anti-friction and wear resistance which is resulted from a graphite-rich mechanical mixed layer (GRMML) formed on the contact surface. Hard SiC particles mixed with GRMML played a load-bearing role at high load when relative motion occurs. After heat treatment at 400 °C for 1 h, the wear rate of the hybrid composite decreased with an increase in microhardness. During sliding, the temperature of the hybrid composite occured less change than Ni–P–SiC coating and further guaranteed the stable state of the whole wear process.

Electroless plating : fundamentals and applications

Abstract: Many texts have been written on surface finishing over the years that deal with electroless deposition as a sidelight. Through the talents and efforts of Glenn Mallory and Juan Hajdu, a comprehensive text, entitled Electroless Plating: Fundamentals and Applications, is available through AESF Headquarters. The editors have combined the efforts of 27 contributing authors to produce a wide-ranging text that covers both fundamental and applied aspects of the subject. Published by the AESF, the book was first introduced at SUR/FIN ‘91—Toronto.

Structure of Chemically Deposited Nickel

Abstract: An analysis was made of the structure of the Ni deposit produced by the catalytic Ni reduction process. X‐ray and electron diffraction revealed that the Ni deposit was an amorphous solid. The structure appeared to be unrelated to and independent of the nature of the substrate and thickness of the deposit.Metallographic examination revealed a dense material, free of voids, and perfect conformity to the substrate surface profile. Etching produced a lamellar structure, the variation in etching intensity being interpreted as variations in dissolved P. In platings, the lamellae lay parallel to the plane of the substrate. Growth faults were observed traversing the thickness dimension from substrate surface irregularities. The amorphous structure reverted to a crystalline phase mixture of Ni and at low temperatures with a large heat evolution.

Structural changes induced by heating in electroless nickel-phosphorus alloys

Abstract: Structural changes induced by heating were studied in electroless nickel-phosphorus alloy coatings at three phosphorus compositions: 1%–3%, 6.5%–8% and 10.5%–11% (by weight). X-ray diffraction patterns and pole figures for the (111) and (200) diffraction lines were obtained for as-plated coatings and coatings heated to temperatures from 235°C to 800°C. Microhardness tests were run on each coating. The low phosphorus composition (1%–3% P) as deposited was crystalline. It was single-phase nickel with an indication of a weak (100) texture. The strength of this texture increased with temperatures up to about 535°C. The Ni 3 P phase was detected at 425°C. The intermediate composition (6.5%–8% P) as deposited exhibited the diffraction pattern of an amorphous material. The f.c.c. nickel structure with preferred orientation appeared after heating above 350°C. The texture was (110) and increased in strength with temperature to 800°C. A weak secondary texture, (100), was detected at higher temperatures. Ni 3 P was detected above 400°C. The high phosphorus alloy (10.5%–11% P) as deposited appeared amorphous. After heating to 385°C both nickel and Ni 3 P diffraction patterns were observed, but there was no confirmed preferred orientation in nickel. A duplex texture, consisting of (110) and (111), was found after heating to 425°C. Hardness of the coatings increased with temperature to a maximum of 1000 HK 200 at about 350°C. Hardness decreased for higher heating temperatures, but by less for higher phosphorus compositions. In the intermediate and high phosphorus alloys, Ni 3 P was the matrix phase after heating to 800°C.

Electroless Nickel-PTFE Composite Coatings

Abstract: The scope of electroless nickel has been increased by codepositing materials such as silicon carbides, ceramics, diamonds and fluoropolymers. This is achieved by taking advantage of different but o...

The performance of electroless nickel/PTFE composites

Abstract: Proprietes tubologiques et de resistance a la corrosion des revetements composites nickel/PTFE