Effect of MoS₂ Nanoparticle Co‑Deposition on Nickel Composite Coatings from Succinic Acid Electrolytes

Metal Matrix Composites (MMCs) constitute an important class of engineered materials designed to overcome the inherent limitations of pure metals, particularly in terms of mechanical strength, wear resistance, corrosion protection, and tribological performance. By incorporating reinforcing phases like hard ceramic particles or 2D solid lubricants into a metallic matrix, MMCs can achieve enhanced functional properties that are difficult to obtain through alloying or conventional surface treatments alone.[1]

The development of such coatings, however, must comply with increasingly stringent environmental and health regulations. Within this context, the European project MOZART aims to deliver REACH-compliant alternatives to hard-chrome (HC) coatings by developing nickel-based MMCs capable of matching HC performance.[2] Because boric acid, a common buffering agent in commercial nickel baths, has been classified as a substance of very high concern (SVHC) due to its reproductive toxicity, safer substitutes are required. Literature reports that di- and tri-carboxylic acids such as citric acid are effective buffering agents within the operative pH range of nickel baths (pH 3–5).[3]

In this work, succinic acid is proposed as a sustainable buffering agent for the electrodeposition of nickel-based MMCs reinforced with molybdenum disulphide (MoS₂) nanoparticles. Successful co-deposition requires stable nanoparticle dispersions in the electrolyte; therefore, several surfactants were evaluated to mitigate MoS₂ agglomeration and promote uniform incorporation into the deposit.[4] The influence of each surfactant on bath stability, deposition efficiency, and the resulting co-deposition behaviour was investigated to assess whether MoS₂ incorporation effectively provides solid lubrication, reduces the coefficient of friction, and enhances the wear resistance of the resulting composite coatings.

[1] Wasekar NP, Lavakumar B. Strengthening mechanisms and tribological aspects of ceramic particle reinforced electrodeposited metal matrix composites – A review. J Alloys Compd 2025;1037:182288. https://doi.org/10.1016/j.jallcom.2025.182288.

[2] European Union, Mozart project [Online]. Accessed on 10th December, 2025. Available at https://www.mozart-project.eu/# n.d.

[3] Bigos A, Wolowicz M, Janusz-Skuza M, Starowicz Z, Szczerba MJ, Bogucki R, Beltowska-Lehman E. Citrate-based baths for electrodeposition of nanocrystalline nickel coatings with enhanced hardness. J Alloys Compd 2021;850:156857. https://doi.org/10.1016/j.jallcom.2020.156857.

[4] Liu C, Zhen H, Huang Q, Chen W, Mai Y, Zhang L, Jie X. Improvement in Tribological and Anticorrosion Performances of Co-MoS2 Composite Coatings. J Mater Eng Perform 2023;32:2237–48. https://doi.org/10.1007/s11665-022-07260-y.