Influence of corrosion of carbon steels by corrosion products of the thermally sprayed zinc coating were studied by means of immersion test and electrochemical technique in 1/20 mol/dm³ Na₂SO₄ solution at 303K.Zinc carbonate(ZnCO₃)and Zinc oxide(ZnO)powders of the commercial reagent produced a slurry form.Slurry particles were deposited onto carbon steel sheets.The corrosion rate of carbon steel,which was measured by weight losses,decreased in order:Fe > ZnCO₃/Fe > ZnO/Fe.After the immersion test of ZnO/Fe,zinc metal was deposited on the carbon steel surface.The corrosion of carbon steel was dependent on the reduction reaction of the dissolved oxygen and the precipitation reaction of zinc.

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Cold spraying is a promising process to fabricate functional coatings.Using this process,particles are accelerated by supersonic gas flow and finally impact to substrate and adhere to a substrate by occurring plastic deformation.The plastic deformation of both sprayed metallic particle and metallic substrate cause the removal of surface oxide layers and newlyformed surfaces are explored.The newly-formed surface yields the metallic bond,and then the cold spray deposition can be obtained.Therefore,the substrate conditions should be considered to understand the cold spray process.This paper aims to investigate the effect of substrate temperature on the adhesion strength of cold-sprayed coatings.The adhesion strength was increased with the substrate temperature.It is in part due to the thermal softening of substrate.However,the adhesion strength was not increase with a specific material combination:soft feedstock particle and substrate covered by thick oxide layers.The soft particle seems to be difficult to cause the effectual removal of surface oxide layers.Therefore,surface oxidation is decrease adhesion strength.

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