**7. Applications**

Electroplated nickel composite/nanocomposite coatings find applications in machining and finishing of tools requiring excellent corrosion and wear resistance, low friction, and high thermal stability. Wear, friction, and corrosion pose a serious threat to machine lifespan, energy consumption, and performance. These phenomena also compromise the safety of the person‐ nel where the machine is used. Therefore, engineers prefer machines that have long lifespan, save energy, and have better performance throughout its service life. These machines or tools are made of lighter and cost-effective materials such as aluminium and steel, to enhance their quality; materials harder and chemically stable than them are used as coatings to protect them from surface degradation. Nickel, nickel alloy, and composite/nanocomposite coatings are perfect candidates for improving the quality of these materials.

Ni–SiC nanocomposite coatings are used to offer wear protection of aluminium-made engine pistons in automotive industry [70]. These parts operate under high temperatures and wear conditions. Other candidates that perform similar function of lining of cylinders in aluminium engines are Ni–Al2O3, TiO2, WC, Cr2O3, etc. [71].

Electrodeposited Ni/diamond coatings have found applications in grinding and cutting tools, such as precision cutting wheels for dicing semiconducting silicon plates [71]. These also include nickel alloy composite coatings such as Ni–W reinforced with diamond nanoparticles. These coatings exhibit high hardness, excellent wear resistance, and elevated thermal stability.

Ni–PTFE composite coatings find use in precise mechanical parts [17]. These possess selflubricating properties and are convenient for applications that require low friction. Other suitable coatings to perform similar functions are Ni–CNT, MoS2, graphite, Si3N4, Ni–B, and BN composite coatings. They also exhibit high oxidation resistance.
