The Influence of Air Pressure in Electric Arc Spraying on the Properties of 30KhGSA/20Kh13 Bilayer Coatings

This study investigates the structural formation and performance characteristics of coatings produced by electric arc spraying using 20Kh13 steel wire on a 45 steel substrate with an adhesive interlayer made of 30KhGSA steel. Particular attention is paid to the effect of spraying air pressure (0.4–0.6 MPa) on the morphology, phase composition, microhardness, elastic modulus, and tribological properties of the resulting coatings. Microstructural and X-ray phase analyses revealed that increasing air pressure leads to higher coating density, reduced porosity (~2–3%), and increased content of the Fe3O4 oxide phase. Nanoindentation tests showed that the highest microhardness (up to 270 HV) and elastic modulus values were observed at 0.4 MPa, while the greatest structural integrity and stable frictional behavior were achieved at 0.6 MPa. Under both dry and lubricated conditions, the coatings exhibited stable performance and a low coefficient of friction (0.10–0.12 in oil), confirming the potential of the developed technology for the restoration and strengthening of component surfaces operating under combined loading and aggressive environmental conditions.