Corrosion Behaviour of Powder Metallurgy Biomaterials from Phosphated Carbonyl-Iron Powders

Abstract

Phosphate coated carbonyl-iron powders were compacted and sintered to investigate the effect of 0.5 and 1.0wt.% of phosphorus supplied through a phosphate coating on the microstructure and corrosion of sintered samples. The resultant materials consisted of spheroidized iron or iron oxide particles surrounded by a solidified liquid phase composed of various ferric phosphate compounds. The addition of phosphorus to carbonyl iron i) raised the fractal dimension of time series generated by the open –circuit potential fluctuations from 1.14 to about 1.5, ii) more than tripled the corrosion rate and iii) made the steady-state corrosion potential more noble (lower phosphorus content) or less noble (higher phosphorus content) than the corrosion potential of carbonyl-iron sample.