Effect of coating bath composition on the properties of electroless nickel–boron films
TL;DR: In this article, the effect of borohydride, thallium acetate, ethylenediamine and sodium hydroxide concentrations, and the coating bath temperature on both the coating rate and boron content of the electroless Ni-B films was investigated systematically.
Abstract: The effect of borohydride, thallium acetate, ethylenediamine and sodium hydroxide concentrations, and the coating bath temperature on both the coating rate and boron content of the electroless Ni–B films was investigated systematically. The Ni–B coating rate increased with the increase in thallium acetate and sodium hydroxide concentrations, but it was not very sensitive to the borohydride concentration. Below 90 g L − 1 ethylenediamine concentration the coating efficiency was significantly low and above this value as the ethylenediamine concentration increased the coating rate decreased slightly. Below 85 °C the coating rate was very low and above this temperature it was insensitive to the bath temperature. The boron content of Ni–B film increased with the increase in the borohydride concentration and the bath temperature, and decreased with the increase in thallium acetate and ethylenediamine concentrations. Up to 50 g L − 1 sodium hydroxide concentration, the boron content of the film increased and above this concentration it was insensitive to the sodium hydroxide concentration. As the boron content of Ni–B film increased, both the corrosion resistance and microhardness of Ni–B film increased. Heat treatment brought significant improvement in the microhardness but the corrosion resistance of Ni–B film was observed to decrease due to the disappearance of the amorphous characteristics of the as-deposited Ni–B film and the formation of the Ni–B compound phases.
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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.
477 citations
TL;DR: In this paper, the influence of boron concentration in the Ni-B alloys on their structure, morphology, electrochemical and corrosion behavior, physico-mechanical and electrical properties was investigated using X-ray diffractometry (XRD), scanning electron microscopy (SEM), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS).
104 citations
TL;DR: In this paper, a taguchi-based grey relational analysis is employed for the optimization of this multiple response problem using an L 27 orthogonal array to minimize the friction and wear characteristics of electroless Ni-B coatings simultaneously by optimizing the three coating parameters.
87 citations
TL;DR: In this article, the hardness and friction coefficient of as-plated and heat treated Ni-B and NiNi-B-TiO2 composite coatings were determined by Vickers diamond indentation and indentation scratch tests and compared with Ni−B coatings.
86 citations
TL;DR: In this paper, the structure of electroless nickel-boron with a boron content around 5.5% was investigated in the as deposited and heat treated states by X-ray diffraction and by transmission electron microscopy on thinned cross-sections prepared by focused ion beam technique.
Abstract: The structure of electroless nickel–boron with a boron content around 5 wt.% was investigated in the as deposited and heat treated states by X-ray diffraction and by transmission electron microscopy on thinned cross-sections prepared by focused ion beam technique. In the as-deposited state, the presence of areas with short range order has been observed. This shows that electroless nickel–boron coatings with high boron content are not fully amorphous, as is usually stated. After heat treatment, the structure of electroless nickel–boron appeared constituted of nanocrystalline nickel–boride Ni3B.
84 citations
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Book•
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.
963 citations
TL;DR: In this paper, the hardness and wear resistance of electroless Ni-B coatings were evaluated using X-ray diffraction (XRD), Leitz microhardness tester and a pin-on-disc wear test apparatus.
Abstract: The present work aims to study the hardness and wear resistance of electroless Ni–B coatings. An alkaline bath having nickel chloride as the source of nickel and borohydride as the reducing agent was used to prepare the electroless Ni–B coatings. The structure, microhardness and wear resistance of electroless Ni–B coatings, both in as-plated and heat-treated conditions, were evaluated using X-ray diffraction (XRD), Leitz microhardness tester and a pin-on-disc wear test apparatus. XRD patterns reveal that electroless Ni–B coatings are amorphous in as-plated condition and undergo phase transformation to crystalline nickel and nickel borides upon heat-treatment. The microhardness of the electroless Ni–B coatings increases with increase in heat-treatment temperature and exhibit two maxima in the hardness vs. heat-treatment temperature curve. The specific wear rate increases with increase in applied load from 20 to 40 N and at all applied loads, the specific wear rate and coefficient of friction are less for heat-treated electroless Ni–B deposits compared to that obtained for as-plated ones. The wear process of electroless Ni–B coatings is governed by an adhesive wear mechanism.
247 citations
TL;DR: The results of scratch tests show that the Ni-B deposits have good tribological properties under external solicitations as discussed by the authors, they are hard, wear and abrasion resistant, and also have good adhesion to the aluminium substrate.
Abstract: Electroless nickel–boron baths reduced with sodium borohydride can be stabilized with various agents such as thallium nitrate or lead tungstate with no fundamental modification of deposition rates and stability. To improve the mechanical properties of electroless nickel–boron deposits, various heat treatments are applied. At low temperatures, no fundamental changes in the deposit structure are observed, only an improvement of adhesion on aluminium substrate. The values of the Knoop microhardness obtained on these heat-treated deposits are near 600 hk 100 . At higher temperatures, structural changes take place and the nickel–boron deposits crystallize. The microhardness rises until 1050 hk 50 for heat treatments at 350 °C for 4 h. A diffusion layer between the electroless nickel deposit and the aluminium substrate appears at high heat treatment temperatures. The results of scratch tests show that the Ni–B deposits, with or without heat treatments, have good tribological properties under external solicitations. They are hard, wear and abrasion resistant, and also have good adhesion to the aluminium substrate.
178 citations
TL;DR: In this article, the formation of Ni-P/Ni-B duplex coatings by electroless plating process and evaluation of their hardness, wear resistance and corrosion resistance were dealt with.
160 citations
TL;DR: In this paper, the authors examined the possibility of depositing a thick autocatalytic electroless Ni-B plating on aluminium alloys and proposed an alkaline bath containing sodium borohydride as the reducing agent.
Abstract: Light alloys are more and more widely used, notably in aeronautics and the car industry. To improve their superficial properties, they can be covered with a hard and wear resistant protective layer. In this article, we examine the possibility of depositing a thick autocatalytic electroless Ni–B plating on aluminium alloys. We propose an alkaline bath containing sodium borohydride as the reducing agent. The deposition rate is held constant by a regular replenishment of the Ni–B bath allowing a rate of about 25 μm/h. The Knoop microhardness of the Ni–B deposits after the bath reaches about 750 hk100. Appropriate heat treatment can increase the deposit microhardness up to more than 1000 hk100 but must be applied with regard to the substrate properties. The study of these heat treatments will be published in a further paper.
160 citations