Electrophoretic deposition of CaP–TiSiN composite coatings on 316L stainless steel: corrosion resistance and in vitro cytocompatibility

The EPD technique was used to synthesize CaP-TiSiN composite coatings on 316 L stainless steel to enhance its surface mechanical, electrochemical, and biological properties. The fabricated coatings were characterized by SEM, EDS, XRD, water contact-angle determination, Vickers microhardness test, scratch adhesion test, potentiodynamic polarization, and in vitro MTT test on MC3T3-E1 osteoblast-like cells. The CaP-TiSiN composite coating possessed a dense, relatively homogeneous microstructure with uniform distribution of the constituents. The microhardness value rose from 177.0 HV of bare 316 L to 602.4 HV of the CaP-TiSiN coating, and the scratch critical load was 18.8 N. Corrosion rate dropped from 0.00057 to 0.00007 mm/year, and the water contact angle became 54.3°, which indicates improvement in wettability. In MTT test, the CaP-TiSiN-coated samples showed maximum metabolic activity at all times, which was achieved as high as 116.3% on day 5 and significantly higher than TiSiN coating (p < 0.05) and HA coating on day 5 (p = 0.041). This suggests that EPD-synthesized CaP-TiSiN composite coatings could be employed as efficient surface modifications of 316 L stainless steel in biomedicine.