Investigation Of Plasma Electrolytic Carbonitriding Technique In Solution

In this dissertation, plasma electrolysis carburising, nitriding andcarbonitriding technique in solution was applied to improve the wear resistanceand anti-corrosion properties of steel for Q235 steel at open environment andgiven electrolyte.Plasma electrolysis saturation technique in solution was applied for surfacemodified of Q235 steel. The feasibility of rapid carburising, nitriding andcarbonitriding saturation was discussed and also the stability of electrolysissystem.The thickness of saturation layer was measured and analyzed the phasecomposition,morphology,composition,Roughness,microhardness from saturationlayer into matrix interior. The wear resistance and anti-corrosion properties ofsamples were measured.The results indicated that applied DC pulse power in formamide andaqueous solution of urea could not achieve carburising,nitriding layer in Q235steel.Howereve, The results are satisfactory in ethanolamine electrrolyte. Inspecifically electrolyte,voltage and treated time were the important parametersto realize plasma electrolysis saturation.The saturated layer thickness increasedwith voltage and treated time and the maximal thickness was 75 μm Thesaturation layer was compactest when the treated voltage was 150 V and timewas 75 s. The maximal microhardness of saturation layer was HV770, whichwas the 4.5 times of matrix. The surface roughness increased with the increasedof treated time and voltage The carbonitriding saturation layer were composedby α-Fe_C-N,γ-Fe_C-N,Fe₃C,Fe₅C₂ and ε-Fe_2-3N. The wear resistance is more than3 times of matrix. The matrix natural corrosion potential was -930 mV while thetreated sample was -550 mV.