Resistance to Hydrochloric Acid Solution of Fe-Cr-Mo-8P-2C Amorphous Coatings Sprayed by HVOF Process

Three kinds of Fe-8P-2C alloy powders containing 10 mass% Cr(10 Cr), 20 mass% Cr(20 Cr) and 10 mass% Cr-10 mass% Mo (10 Mo), respectively, were thermally sprayed by a high velocity oxy-fuel (HVOF) process. The as-sprayed coatings of the 10 Cr and 20Cr alloys are a mixture of an amorphous phase and a small quantity of crystalline phases, while as-sprayed coating of the 10 Mo alloy is composed of only an amorphous phase. The anodic polarization curves of the coatings of the 10 Cr and 20 Cr alloys exhibited an activation-passivation transition in 1N HCl solution. On the other hand, the coating of the 10 Mo alloy showed no active state and the lowest current density among the alloy coatings in the anodic polarization curve. The passive state of the coating of the 10 Mo alloy was stable compared with the other coatings. The coating of the 10 Mo alloy also underwent no corrosion in 1 N HCl solution at 0.5 and 1.0 V (vs. SCE), whereas Inconel 600 alloy plate was attacked remarkably. Other materials noted: SUS316L, MSFNi4 coating.