Ni–TiO 2 nanocomposite coatings with various contents of TiO 2 nanoparticles were prepared by electrodeposition in a Ni plating bath containing TiO 2 nanoparticles to be codeposited. The influences of the TiO 2 nanoparticle concentration in the plating bath, the current density and the stirring rate on the composition of nanocomposite coatings were investigated. The composition of coatings was studied by using energy dispersive X-ray system (EDX). The wear behavior of the pure Ni and Ni–TiO 2 nanocomposite coatings were evaluated by a pin-on-disc tribometer. The corrosion performance of coatings in 0.5 M NaCl, 1 M NaOH and 1 M HNO 3 as corrosive solutions was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy methods (EIS). The microhardness and wear resistance of the nanocomposite coatings increase with increasing of TiO 2 nanoparticle content in the coating. With increasing of TiO 2 nanoparticle content in the coating, the polarization resistance increases, the corrosion current decreases and the corrosion potential shifts to more positive values.

Ni–TiO2 nanocomposite coating with high resistance to corrosion and wear

The operating process, versatility and the increasing research interest in optimising the process and products technology in the electroless plating method of metal coating, particularly, the electroless nickel plating of metallic substrates such as mild steel, necessitates the writing of this review. It is also aimed at providing more literature information, both of the past and the present published research in this field. In this paper, electroless nickel plating is introduced. The various nickel plating solutions and baths’ operating parameters; main types of electroless nickel plating; the mechanism involved in the plating process; application of the nickel plating process to iron powders; advantages and disadvantages and the process’s other applications are reviewed. Electroless nickel plating produces an amorphous deposit in the as-plated condition. The deposit is not dependent on current distribution and hence it is almost uniform in thickness. Electroless nickel plating is far more difficult to remove chemically than conventional nickel deposits due to its superior corrosion resistance. The deposit has a good wettability and is generally hard. However, its bath control is more complex than with electroplating. The bath also has lower efficiency and higher operating costs, even without the use of electricity.

Electroless Nickel Plating – A Review

Growth in nanocoatings technology is moving towards implementing nanocoatings in many sectors of the industry due to their excellent abilities. Nanocoatings offer numerous advantages, including surface hardness, adhesive strength, long-term and/or high-temperature corrosion resistance, the enhancement of tribological properties, etc. In addition, nanocoatings can be applied in thinner and smoother thickness, which allows flexibility in equipment design, improved efficiency, lower fuel economy, lower carbon footprints, and lower maintenance and operating costs. Nanocoatings are utilised efficiently to reduce the effect of a corrosive environment. A nanocoating is a coating that either has constituents in the nanoscale, or is composed of layers that are less than 100 nm. The fine sizes of nanomaterials and the high density of their ground boundaries enable good adhesion and an excellent physical coverage of the coated surface. Yet, such fine properties might form active sites for corrosion attack. This paper reviews the corrosion behaviour of metallic, ceramic, and nanocomposite coatings on the surface of metallic substrates. It summarises the factors affecting the corrosion of these substrates, as well as the conditions where such coatings provided required protection.

A Review on the Corrosion Behaviour of Nanocoatings on Metallic Substrates

Mechanical and electrochemical properties of ultrasonic-assisted electroless deposition of Ni–B–TiO2 composite coatings

The corrosion protection performance of electroless deposited nickel–phosphorus (Ni–P) alloy coatings containing tungsten (Ni–P–W) or nano-scattered alumina (Ni–P–Al 2 O 3 ) composite coatings on low carbon steel was studied. The effect of heat treatment on the coating performance was also studied. The optimum conditions under which such coatings can provide good corrosion protection to the substrate were determined after two weeks of immersion in 3.5% NaCl solution. Electrochemical impedance spectroscopy (EIS) and polarization measurements have been used to evaluate the coating performance before and after heat treatment. The Ni–P–W coatings showed the highest surface resistance compared with Ni–P–Al 2 O 3 and Ni–P. The surface resistance of Ni–P–W coatings was 12.0 × 10 4  Ω cm 2 which is about the double of the resistance showed by Ni–P–Al 2 O 3 (7.00 × 10 4  Ω cm 2 ) and twenty times greater than the surface resistance of Ni–P (0.78 × 10 4  Ω cm 2 ). XRD analysis of non-heat-treated samples revealed formation of a protective tungsten phosphide phase. Heat treatment has an adverse effect on the corrosion protection performance of tungsten and alumina composite coatings. The surface resistance decreased sharply after heat treatment.

Corrosion behavior of electroless Ni–P alloy coatings containing tungsten or nano-scattered alumina composite in 3.5% NaCl solution

Evaluation of corrosion and erosion–corrosion resistances of mild steel in sulfide-containing NaCl aerated solutions

The performance of ternary electroless deposited Ni–P–W and Ni–P–alumina composite coatings on low carbon steel substrates was studied. The effect of experimental parameters, such as temperature, pH, nickel sulfate concentration, sodium hypophosphite concentration, sodium citrate concentration, and deposition time on the deposition rate were investigated. The coating brightness, coherence, and uniform surface distribution were improved due to addition of W and alumina. The coating performance was evaluated based on the wear-resistance, micro-hardness, and corrosion resistance. The Ni–P–W ternary alloy coatings showed the highest micro hardness, wear-resistance, brightness, and corrosion resistance. The improvement in the performance of Ni–P–W coatings can be explained by the formation of a tungsten phosphide phase.

Electroless deposition of ternary Ni–P alloy coatings containing tungsten or nano-scattered alumina composite on steel

Anodic oxide film was grown on aluminum alloy in 5-sulfosalicylic acid electrolyte. The corrosion resistance of the oxide film formed at different electrolyte temperatures and concentrations was studied using electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The results obtained indicate that the growth of oxide film on aluminum alloys greatly improved the corrosion resistance. The best corrosion resistance was obtained by oxide film growth with 0.5 M solution at relatively low temperature (4 °C). Hardness value was also increased as the electrolyte temperature decreased due to the formation of dense oxide film. At low bath temperature (near 0 °C) the microhardness reaches its maximum value and slightly decreases as the film thickness increases. According to EIS and hardness measurements, 5-sulfosalicylic acid is a suitable electrolyte for anodic film growth of aluminum surface.

M.A. Shoeib

Papers

Corrosion behavior of electroless Ni–P alloy coatings containing tungsten or nano-scattered alumina composite in 3.5% NaCl solution

Evaluation of corrosion and erosion–corrosion resistances of mild steel in sulfide-containing NaCl aerated solutions

Electroless deposition of ternary Ni–P alloy coatings containing tungsten or nano-scattered alumina composite on steel

Growth and characterization of anodic films on aluminum alloys in 5-sulfosalicylic acid solution

High electrochemical energy-storage performance promoted by SnSe nanorods anchored on rGO nanosheets