Electroless deposition of nickel-boron coatings using low frequency ultrasonic agitation: Effect of ultrasonic frequency on the coatings.

Title Electroless deposition of nickel-boron coatings using low frequency ultrasonic agitation: Effect of ultrasonic frequency on the coatings.
Authors L. Bonin; N. Bains; V. Vitry; A.J. Cobley
Journal Ultrasonics
DOI 10.1016/j.ultras.2017.01.021
Abstract

The effect of ultrasound on the properties of Nickel-Boron (NiB) coatings was investigated. NiB coatings were fabricated by electroless deposition using either ultrasonic or mechanical agitation. The deposition of Ni occurred in an aqueous bath containing a reducible metal salt (nickel chloride), reducing agent (sodium borohydride), complexing agent (ethylenediamine) and stabilizer (lead tungstate). Due to the instability of the borohydride in acidic, neutral and slightly alkaline media, pH was controlled at pH 12±1 in order to avoid destabilizing the bath. Deposition was performed in three different configurations: one with a classical mechanical agitation at 300rpm and the other two employing ultrasound at a frequency of either 20 or 35kHz. The microstructures of the electroless coatings were characterized by a combination of optical Microscopy and Scanning Electron Microscope (SEM). The chemistry of the coatings was determined by ICP-AES (Inductively Coupled Plasma - Atomic Emission Spectrometry) after dissolution in aqua regia. The mechanical properties of the coatings were established by a combination of roughness measurements, Vickers microhardness and pin-on-disk tribology tests. Lastly, the corrosion properties were analysed by potentiodynamic polarization. The results showed that low frequency ultrasonic agitation could be used to produce coatings from an alkaline NiB bath and that the thickness of coatings obtained could be increased by over 50% compared to those produced using mechanical agitation. Although ultrasonic agitation produced a smoother coating and some alteration of the deposit morphology was observed, the mechanical and corrosion properties were very similar to those found when using mechanical agitation.

Citation L. Bonin; N. Bains; V. Vitry; A.J. Cobley.Electroless deposition of nickel-boron coatings using low frequency ultrasonic agitation: Effect of ultrasonic frequency on the coatings.. Ultrasonics. 2017;77:6168. doi:10.1016/j.ultras.2017.01.021

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See more Boron products. Boron Bohr ModelBoron (atomic symbol: B, atomic number: 5) is a Block P, Group 13, Period 2 element with an atomic weight of 10.81. The number of electrons in each of boron's shells is 2, 3 and its electron configuration is [He] 2s2 2p1. The boron atom has a radius of 90 pm and a Van der Waals radius of 192 pm. Boron was discovered by Joseph Louis Gay-Lussac and Louis Jacques Thénard in 1808 and was first isolated by Humphry Davy later that year. Boron is classified as a metalloid is not found naturally on earth. Elemental BoronAlong with carbon and nitrogen, boron is one of the few elements in the periodic table known to form stable compounds featuring triple bonds. Boron has an energy band gap of 1.50 to 1.56 eV, which is higher than that of either silicon or germanium. The name Boron originates from a combination of carbon and the Arabic word buraqu meaning borax.

Nickel

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