Specific Surface Area and Pore Size Distribution of Rusted Steel after Chemical Conversion in a 0.1M Na₂MoO₄-H₃PO₄ Aqueous Solution

Abstract

All specimens as rusted, phosphated, and chemically treated with a 0.1M Na₂MoO₄-H₃PO₄ solution after wire-brush scratching were found to have the same BET type of adsorption isotherm by N₂ adsorption. Their pore size distribution peaked at about 100nm radius, and then decreased abruptly until 500nm and thereafter slowly until 1500nm. The chemically treated wire-brush scratched rusted steel was small in specific surface area and in all pore volumes as compared with other specimens probably due to the formation of conversion coatings at exposed bare areas which have existed on the rusted surface or been caused by wire-brush scratching. It seems that sludges were adsorbed at these bare areas and caused pores to be partly clogged.