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

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.