Improved multilayer coatings by combined use of electrochemical and ultra-short pulsed laser deposition techniques

• Challenging base materials were coated by combining electrochemical and USPLD methods.
• Pretreatment steps were simplified compared with traditional electrochemical methods.
• Hazardous chemicals were not used during the pretreatment process.
• Ni and Ni-Cr(III) coatings on Al, SS316L and glass show good adhesion strength and scratch resistance.
• Ni and Ni-Cr(III) coatings on PC show mechanical properties sufficient for many applications.

Electrochemical and ultra-short pulsed laser deposition (USPLD) methods were combined to produce multilayer coatings on various base materials that are challenging to be coated by using traditional electrochemical techniques. A thin and well-adherent metallic intermediate layer was coated on each base material by USPLD method before final nickel or nickel-trivalent chrome coating by electrochemical methods. In this way, the pretreatment steps for electrochemical deposition were simplified compared with traditional methods and hazardous chemicals were not used during the pretreatment process. The morphology, coating thickness and the elemental composition of the multilayer coatings were analyzed using scanning electron microscope (SEM) coupled with Energy Dispersive X-ray spectroscopy (EDS), and the adhesion strengths of each coating were tested by scratch and pull-off tests. The results show good adherence for all studied coatings on aluminum alloy (6082) and stainless acid-proof steel (SS316L), whereas obtaining a sufficient adhesion of coatings on glass (borosilicate) and polycarbonate (PC) requires a correct choice of coating materials and process steps. The critical loads in scratch test are approximately 20 N for coatings on aluminum and glass, at least 50 N for coatings on SS316L and approximately 5 N for coatings on PC. In pull-off tests, maximum adhesion strengths for coatings on aluminum and SS316L are approximately 25 MPa for electroless coatings and 10 MPa for electroplated coatings. Coatings on glass and PC reach adhesion strengths of approximately 4–9 MPa, which is sufficient for many applications.