{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,17]],"date-time":"2026-03-17T23:47:32Z","timestamp":1773791252633,"version":"3.50.1"},"reference-count":50,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,2,5]],"date-time":"2026-02-05T00:00:00Z","timestamp":1770249600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"national funds through FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","award":["UID\/00285\/2025"],"award-info":[{"award-number":["UID\/00285\/2025"]}]},{"name":"national funds through FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","award":["LA\/P\/0112\/2020"],"award-info":[{"award-number":["LA\/P\/0112\/2020"]}]},{"name":"PRR\u2014Recovery and Resilience Plan","award":["02\/C05-i01\/2022"],"award-info":[{"award-number":["02\/C05-i01\/2022"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Coatings"],"abstract":"<jats:p>The present work investigates the effect of phosphorous-acid-induced pH variation on the electrodeposition of Ni\u2013P coatings and examines how changes in electrolyte composition influence current efficiency, deposition behaviour, microstructure, optical properties, tribological response and wettability. In addition, the study assesses the potential of a post-deposition surface modification using stearic acid to enhance the hydrophobic character of the coatings. Ni and Ni\u2013P layers were electrodeposited on 316L stainless steel using electrolytes containing 0\u201340 g\/L of H3PO3, resulting in progressively lower bath pH and significant changes in deposition kinetics. The introduction of H3PO3 caused a sharp reduction in cathodic current efficiency and deposition rate, producing ultrathin Ni\u2013P films with 20\u201324 at.% P. XRD and SEM analyses showed a transition from highly crystalline Ni to amorphous, nodular Ni\u2013P structures. Tribological tests revealed a pronounced improvement in sliding performance for all Ni\u2013P coatings compared to pure Ni, with sample S2 (5 g\/L of H3PO3) exhibiting the lowest and most stable friction coefficient (~0.30). Wettability studies indicated that all as-deposited Ni\u2013P surfaces were weakly hydrophobic, with surface energies dominated by the dispersive component. A stearic acid post-treatment produced a measurable increase in the water contact angle, indicating successful surface functionalization of the coatings. Overall, this study provides a comprehensive assessment of how phosphorous acid concentration governs the functional behaviour of electrodeposited Ni\u2013P coatings.<\/jats:p>","DOI":"10.3390\/coatings16020205","type":"journal-article","created":{"date-parts":[[2026,2,5]],"date-time":"2026-02-05T15:24:19Z","timestamp":1770305059000},"page":"205","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Effect of Phosphorous Acid-Induced pH Variation on Ni\u2013P Electrodeposition: Influence on Current Efficiency, Deposition Rate, Surface Properties, and Tribological Performance"],"prefix":"10.3390","volume":"16","author":[{"given":"Ilias","family":"Reddah","sequence":"first","affiliation":[{"name":"Mechanical Engineering Department, Abbes Laghrour University Khenchela, P.O. Box 1252, Khenchela 40004, Algeria"},{"name":"Laboratory of Engineering and Sciences of Advanced Materials (ISMA), Abbes Laghrour University Khenchela, P.O. Box 1252, Khenchela 40004, Algeria"}]},{"given":"Laala","family":"Ghelani","sequence":"additional","affiliation":[{"name":"Mechanical Engineering Department, Abbes Laghrour University Khenchela, P.O. Box 1252, Khenchela 40004, Algeria"},{"name":"Laboratory of Engineering and Sciences of Advanced Materials (ISMA), Abbes Laghrour University Khenchela, P.O. Box 1252, Khenchela 40004, Algeria"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4183-6464","authenticated-orcid":false,"given":"Daniela","family":"Santo","sequence":"additional","affiliation":[{"name":"CEMMPRE, ARISE, Department of Mechanical Engineering, University of Coimbra, Rua Lu\u00eds Reis Santos, 3030-788 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-7146-2531","authenticated-orcid":false,"given":"Joana","family":"Neiva","sequence":"additional","affiliation":[{"name":"CEMMPRE, ARISE, Department of Mechanical Engineering, University of Coimbra, Rua Lu\u00eds Reis Santos, 3030-788 Coimbra, Portugal"}]},{"given":"Lu\u00eds","family":"Figueiredo","sequence":"additional","affiliation":[{"name":"SRAMPORT Lda., Rua Ant\u00f3nio S\u00e9rgio 15, 3025-041 Coimbra, Portugal"}]},{"given":"Diogo","family":"Cavaleiro","sequence":"additional","affiliation":[{"name":"CEMMPRE, ARISE, Department of Mechanical Engineering, University of Coimbra, Rua Lu\u00eds Reis Santos, 3030-788 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3643-4973","authenticated-orcid":false,"given":"Sandra","family":"Carvalho","sequence":"additional","affiliation":[{"name":"CEMMPRE, ARISE, Department of Mechanical Engineering, University of Coimbra, Rua Lu\u00eds Reis Santos, 3030-788 Coimbra, Portugal"},{"name":"IPN\u2014LED&MAT\u2014Instituto Pedro Nunes, Laborat\u00f3rio de Ensaios, Desgaste e Materiais, Rua Pedro Nunes, 3030-199 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2217-4584","authenticated-orcid":false,"given":"Susana","family":"Devesa","sequence":"additional","affiliation":[{"name":"CEMMPRE, ARISE, Department of Mechanical Engineering, University of Coimbra, Rua Lu\u00eds Reis Santos, 3030-788 Coimbra, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Ramezani, M., Mohd Ripin, Z., Pasang, T., and Jiang, C.-P. 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