Abstract
Sulfamic acid has been used as descaling and cleaning agent of metal surface. This investigation was made to evaluate the corrosibility of steel and other metals, and to search for the corrosion inhibitor in sulfamic acid solution.
The order of corrosion rate of metals in sulfamic acid was mild steel>>aluminum>copper>brass>>18-8 stainless steel, but the corrosion rate of mild steel was much smaller than that in HCl or in H2SO4.
The corrosion inhibiting effect of thirty-seven compounds was examined by the gravimetric method, and quaternary ammonium salt, thiourea derivatives and acetylenic compounds were found to be effective for the inhibition, especially 1, 3 diethyl thiourea, dipropargyl thioether and S-benzoyl propargyl mercaptan were excellent.
The corrosion inhibiting mechanism was further studied by the rapid polarization characteristics.
