Electroless Ni-P composite coatings
01 Sep 2003-Journal of Applied Electrochemistry (Kluwer Academic Publishers)-Vol. 33, Iss: 9, pp 807-816
TL;DR: In this paper, the authors outline the development of electroless Ni-P composite coatings and highlight the method of formation, mechanism of particle incorporation, factors influencing particle incorporation and the effect of incorporation on the structure, hardness, friction, wear and abrasion resistance, corrosion resistance, high temperature oxidation resistance, and their applications.
Abstract: This review outlines the development of electroless Ni–P composite coatings. It highlights the method of formation, mechanism of particle incorporation, factors influencing particle incorporation, effect of particle incorporation on the structure, hardness, friction, wear and abrasion resistance, corrosion resistance, high temperature oxidation resistance of electroless Ni–P composite coatings as well as their applications. The improvement in surface properties offered by such composite coatings will have a significant impact on numerous industrial applications and in the future they will secure a more prominent place in the surface engineering of metals and alloys.
TL;DR: 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 as mentioned in this paper.
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.
TL;DR: In this article, the authors reviewed the tribological advancement of different electroless nickel coatings based on the bath types, structure and also the tribo testing parameters in recent years.
Abstract: Electroless coating is different from the conventional electrolytic coating as the former does not require any electricity for its operation. The advantages include uniform coating and also nonconductive materials can be coated. Electroless nickel coatings possess splendid tribological properties such as high hardness, good wear resistance and corrosion resistance. For this reason, electroless nickel has found wide applications in aerospace, automobile, electrical and chemical industries. Quest for improved tribological performances has led many researchers to develop and investigate newer variants of electroless nickel coatings like Ni–W–P, Ni–Cu–P, Ni–P–SiC, Ni–P–TiO2, and so on. Also the enhancement of tribological characteristics through modification of the coating process parameters has remained a key point of interest in researchers. The technological advancement demands the development of newer coating materials with improved resistance against wear and tear. Electroless nickel has shown huge potential to fit in that space and so the study of its tribological advancement deserves a thorough and exhaustive study. The present article reviews mainly the tribological advancement of different electroless nickel coatings based on the bath types, structure and also the tribo testing parameters in recent years.
TL;DR: In this article, a detailed review of various strategies to improve the corrosion resistance of microarc oxidation (MAO) coatings on Mg/Mg alloys is presented.
Abstract: The development of biodegradable implants is indeed fascinating and among the various types of materials used in this regard, magnesium and its alloys assume significance. However, the rapid corrosion, generation of a large volume of hydrogen gas, accumulation of the hydrogen bubbles in gas pockets adjacent to the implant, increase in local pH of the body fluid, are the major impediments in using them as an implant material. Hence, development of Mg/Mg alloy based degradable implants requires that (i) they should maintain sufficient mechanical strength and integrity until the affected part of body is healed; (ii) they should exhibit good resistance to corrosion in the body fluid during the initial periods of implantation and subsequently corrode in a controlled and uniform fashion; and (iii) the corrosion products should not exceed the acceptable absorption level of the human body. Reducing the rate of corrosion of Mg is the most appropriate strategy and this can be achieved with the use of alloying, surface treatment/coating and mechanical processing. Surface treatment/coating is a viable approach as it not only enables improvement in corrosion resistance but also provides a suitable surface for better bone bonding and cell growth. Among the various surface modification processes, microarc oxidation (MAO) has received considerable attention since the protective oxide layer would delay the rate of corrosion attack during the initial period of implantation and, the decrease in the extent of hydrogen evolution would enhance the primary neo-formation of bone around the implant. The presence of micropores and cracks on the surface of MAO coatings can be considered as an opportunity or a limitation. The presence of a porous outer layer in MAO coatings would significantly improve the mechanical interlocking effect, the bonding area and stress distribution across the adhesive–substrate interface of the joins, resulting in higher bond strength. However, the presence of a higher pore density on the surface of the MAO coatings increases the effective surface area and thus the tendency of the corrosive medium to adsorb and concentrate into these pores. This would facilitate quicker infiltration of the corrosive medium into the inner regions of the coating and subsequently down to the substrate, thus deteriorating the corrosion resistance of the coating by changing its local pH. The pore density, distribution of pores and interconnectivity of the pores with the substrate are the important factors that decide its corrosion protective ability. In spite of the limitation in corrosion rate, MAO coatings exhibit a slow rate of degradation during the first few weeks and an accelerated degradation in later stages of implantation. Nevertheless, the difficulty in achieving a control over the rate of degradation is still a matter of concern in fabricating implant devices with a desired lifetime. Hence, it is not only essential but also mandatory to increase the corrosion resistance of MAO coatings. In this perspective, this review aims to address the various strategies explored to improve the corrosion resistance of MAO coatings on Mg/Mg alloys. This review provides a detailed outline on how the choice of electrolytes, process parameters, pretreatment, additives, incorporation of ceramic particles and, sealing and post-treatment, influence the porosity and corrosion resistance of MAO coatings on Mg/Mg alloys. In addition, the implications of such modifications/choices on the suitability of the resultant coatings for biomedical applications are discussed. The importance of multifunctional approaches in improving the corrosion resistance as well as imparting a controlled drug delivery, better apatite growth, improved bioactivity, etc. is addressed. The important strategies to improve the corrosion resistance and future prospects are summarized.
TL;DR: In this paper, high phosphorus electroless nickel bath has been used to prepare composite coatings containing alumina powders (50 nm, 0.3 μm and 1.0 μm).
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.
TL;DR: In this article, hardness and wear resistance of two types of electroless coating have been investigated including Ni-P and Ni−P-Al 2 O 3 coatings, which were applied on AISI 1045 steel discs by electroless deposition process and then they were heat treated at 200, 400 and 600°C for 1h.
Abstract: In this research, hardness and wear resistance of two types of electroless coating have been investigated including Ni–P and Ni–P–Al 2 O 3 coatings. These coatings were applied on AISI 1045 steel discs by electroless deposition process and then they were heat treated at 200, 400 and 600 °C for 1 h. Wear resistance of deposits was measured by the pin on disc method and wear surfaces and debris were studied by scanning electron microscopy (SEM). Also, microstructural changes were evaluated by X-ray diffraction (XRD) analysis. The results showed that the existence of alumina particles in Ni–P coating matrix led to an increase in the hardness and wear resistance of the deposits. It was also found that heat treated coatings at about 400 °C have the maximum hardness and wear resistance.
01 Jan 1954
TL;DR: Tabor and Bowden as mentioned in this paper reviewed the many advances made in this field during the past 36 years and outlined the achievements of Frank Philip Bowden, and reviewed the behavior of non-metals, especially elastomers; elastohydrodynamic lubrication; and the wear of sliding surfaces.
Abstract: Originally published in 1950, this classic book was a landmark in the development of the subject of tribology. For this edition, David Tabor has written a new preface, reviewing the many advances made in this field during the past 36 years and outlining the achievements of Frank Philip Bowden. The book covers the behavior of non-metals, especially elastomers; elastohydrodynamic lubrication; and the wear of sliding surfaces, which has gradually replaced the earlier concentration on the mechanism of friction. It remains one of the most interesting and comprehensive works available on a single branch of physics.
01 Jan 1990
TL;DR: The Electroless Plating: Fundamentals and Applications (ESPA) as discussed by the authors is a comprehensive text that covers both fundamental and applied aspects of electroless deposition, and was first introduced at SUR/FIN '91.
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.
TL;DR: In this paper, a mechanism based on two successive adsorption steps is proposed to explain the peculiarities shown by the codeposition of inert particles from electrolytic baths, and a general expression relating the concentration of the embedded particles to the suspension concentration and the electrode overpotential is verified experimentally.
Abstract: To explain the peculiarities shown by the codeposition of inert particles from electrolytic baths, a mechanism based on two successive adsorption steps is proposed. In the first step the particles are loosely adsorbed, and they are in equilibrium with the particles in suspension. In the second step the particles are irreversibly adsorbed. Making a few elementary hypotheses about the mechanism that governs the two steps it is possible to deduce a general expression relating the concentration of the embedded particles to the suspension concentration and the electrode overpotential. This relationship is verified experimentally.
TL;DR: In this article, the effects of CNTs on the tribological properties of these composites were evaluated, and the results demonstrated that the Ni-P-CNT electroless composite coating exhibited higher wear resistance and lower friction coefficient than Ni−P-SiC and Ni-p-graphite composite coatings.
Abstract: Ni–P–carbon nanotube (CNT) composite coating and carbon nanotube/copper matrix composites were prepared by electroless plating and powder metallurgy techniques, respectively. The effects of CNTs on the tribological properties of these composites were evaluated. The results demonstrated that the Ni–P–CNT electroless composite coating exhibited higher wear resistance and lower friction coefficient than Ni–P–SiC and Ni–P–graphite composite coatings. After annealing at 673 K for 2 h, the wear resistance of the Ni–P–CNT composite coating was improved. Carbon nanotube/copper matrix composites revealed a lower wear rate and friction coefficient compared with pure copper, and their wear rates and friction coefficients showed a decreasing trend with increasing volume fraction of CNTs within the range from 0 to 12 vol.% due to the effects of the reinforcement and reduced friction of CNTs. The favorable effects of CNTs on the tribological properties are attributed to improved mechanical properties and unique topological structure of the hollow nanotubes.