Studying the behavior of Ni-Co-P and Ni-Co-P-B4c electroless coatings and heat treatment on mechanical and corrosion properties of AISI 4140 steel

• Main Authors: Wais, Alaa Mohammed Hussein, AbidAli, Abdul Raheem K.
• Format: Conference Proceeding
• Language: English
• Subjects: Alloy plating; Annealing; Boron carbide; Chlorides; Chromium molybdenum steels; Cobalt; Coefficient of friction; Corrosion; Corrosion potential; Corrosion resistance; Corrosion resistant steels; Corrosive wear; Electroless coating; Electroless coatings; Electroless nickel plating; Grain size; Heat treatment; High strength steels; Microhardness; Reducing agents; Substrates; Surface roughness; Wear rate; Wear resistance; Wear tests
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0149026

The aims of this work to study the hardness, wear resistance and corrosion resistance of as-plated and heat treatment of Ni-Co-P-B4C electroless coatings. Ni-Co-P and Ni-Co-P-B4C composite were coated on substrate (AISI 4140 steel) with different concentration for B4C (0.3 g/l, 0.5 g/l and 0.7 g/l) in bath of an electroless coating. After the coating finish, the samples were annealed at (400 °C, for 1h). The behavior of wear for the composite coatings was calculated with using a pin on disk method at load of (10 N). An alkaline bath having nickel chloride as the source of nickels, Sodium hypophosphite as the reducing agent, Cobalt Chloride as the source of Cobalt and B4C was used to prepare the electroless Ni–Co-P-B4C coatings. The specimens were characterized with XRD, XRD, EDS, FESEM, surface roughness and microhardness. Results of microhardness obtained the maximum hardness at 1020 HV for Ni-Co-P heat treated sample. By comparing results wear test for Ni-Co-P with Ni-Co-P-B4C and Ni-P. An annealed Ni-Co-P had the lower specific wear rate in comparison with the other specimens because of many reasons such as lowest coefficient of friction, larger microhardness, finer grain size and excellent homogenous distribution of Ni3P and Ni particles. Compared to the Ni-P, Ni-Co-P and Ni–Co-P-B4C coating, resistance of corrosion of Ni-Co-P composite coating are better. The adding of B4C made the coating denser, and agglomeration that occurs is very unfavorable to coating, resulting in potential of corrosion of the composite coating becoming negative gradually, lead resistance of corrosion of the composite coating becomes worse.