Advancements in the Preparation and Application of Ni-Co System (Alloys, Composites, and Coatings): A Review

In the field of non-silicon MEMSs (micro-electro-mechanical systems), nickel, with its mature preparation method, good compatibility with non-silicon MEMS processes, and excellent mechanical properties, is one of the commonly used structural materials. By effectively combining it with non-silicon MEMS processes, nickel is widely used in typical process systems such as LIGA (Lithography, Galvanoformung, Abformung)/UV-LIGA (Ultraviolet Lithography, Galvanoformung, Abformung). However, with the rapid development of the non-silicon MEMS field, pure nickel materials are no longer able to meet current material demands. Alternatively, nickel-cobalt composite materials have excellent mechanical properties, thermal stability, corrosion resistance, and good adaptability to processing technology because cobalt has unique advantages as a reinforcing phase, including excellent wear resistance, corrosion resistance, and high hardness. This article examines the current methods for preparing nickel-cobalt alloys by focusing on composite electrodeposition of coatings and analyzing their advantages and disadvantages. Based on this, the effect of the composite electrodeposition conditions on the formation mechanism of nickel-cobalt alloy coatings is discussed. Then, the research status of composite electrodeposition methods mainly based on nickel-cobalt nanocomposites is discussed. Finally, a new direction for future work on nickel-cobalt composite materials mainly composed of nickel-cobalt nanomaterials prepared by composite electrodeposition is proposed, and its application prospects in non-silicon MEMS fields are discussed.