Pulse Plating of Ni-W-B Coating and Study of Its Corrosion and Wear Resistance
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TRODUCTION
THE surface is the most important part of the engineering components because most failures initiate from the surface defects. One approach to improving the corrosion and wear resistance of metals is using alloying element and composite coatings.[1–5] Among all of the
MIR GHASEM HOSSEINI is with Electrochemistry Research Laboratory, Department of Physical Chemistry, Chemistry Faculty, University of Tabriz, Tabriz, Iran and also with the Engineering Faculty, Department of Materials Science and Nanotechnology, Near East University, 99138 Nicosia, North Cyprus, Mersin 10, Turkey. Contact email: [email protected] SOMAYEH AHMADIYEH, ALI RASOOLI, and SHAHIN KHAMENEH-ASL are with Department of Materials Engineering, Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran. Manuscript submitted January 14, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS A
methods for depositing different coatings, electrodeposition is a vastly used coating deposition method in industrial applications.[6–8] Utilization of pulse plating instead of direct plating leads to higher current densities and more precise control of the coating features so coatings with fine grain size and better properties will be achieved.[9–12] Due to environmental concerns, the pressure to decrease the usage of hard chromium and utilize coatings with better economics and performance has increased.[13] Ni alloy coatings with unique corrosion and wear as well as catalytic properties have been known as a possible alternative and have been widely used in the industry during the past decades.[14,15] Recently, Ni-W-B electroplating coatings have been developed as a feasible and appropriate alternative to hexavalent chromium.[16] Electroplated amorphous and nanocrystalline Ni-W-B alloys are applied as heat
micro-exchangers favorable because of their suitable structure and surface properties, mechanical durability, high hardness, corrosion resistance and appropriate thermal stability.[16–18] A mixture of nanocrystalline and amorphous structure[19] or a completely amorphous one[20] was observed in the Ni-W-B coatings. After heating to 400 C, the amorphous structure transforms to complete the crystalline structure with the precipitation of Ni2B and Ni3B phases.[18,20–23] Ni-W-B coatings could be plated in usual Ni-W baths including compounds from a boron source such as borate,[16,24–26] dimethylamine borane (DMAB),[17,21,22,27] a borohydride,[18,28] boron phosphate[29] or boron particles.[30,31] Drovosekov et al.[32] stated that in the Ni-W-B coating the boron content in the alloy decreases with an increase in the DMAB concentration in the solution because of the acceleration of the reduction of tungsten ions with an increase in the DMAB concentration. Hosseini et al.[16,24,25] optimized operational conditions for plating Ni-W-B ternary alloy coatings and achieved high hardness (850 HV) and corrosion resistance (7000 X cm2) with desirable adherence to the substrate.[24,25] Nagai et al.[27] stated that a grain size reduction of the Ni-W-B coa
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