Volume 32, Issue 1-2

The use of metallic materials for implantable medical devices has prompted numerous studies aimed at characterizing the corrosion susceptibility of these materials and understanding their electrochemical behavior in simulated and actual physiological liquids. This review focuses on the forms of corrosion that are of principal interest for Ti and its alloys in vivo : general corrosion, pitting corrosion, crevice corrosion, galvanic corrosion, and fretting corrosion. It also addresses environmentally assisted cracking in the form of hydrogen embrittlement. Of particular interest is the susceptibility of Ti and its alloys to the different forms of corrosion with regard to both solution chemistry, especially the effect of organic species, and surface characteristics such as oxide composition, surface inclusions, and wear/fretting.

Numerous studies have been performed to investigate the corrosion behavior of Ti and its alloys, 316-type stainless steel, and Co-Cr alloys in simulated and actual physiological liquids. This review is the second of two parts and focuses on 316-type stainless steel and Co-Cr alloys. It deals with the forms of corrosion that are of principal interest with regard to these alloys in vivo : general corrosion, pitting corrosion, crevice corrosion, galvanic corrosion, and fretting corrosion. The review also addresses environmentally assisted cracking in the form of corrosion fatigue and hydrogen embrittlement as well as the use of implantable electrodes.

This work aims at studying the corrosion behavior of electroless Ni-P coating on mild steel substrate heat-treated by microwave and conventional furnace (muffle) annealing. The corrosion behavior of the deposits has been evaluated by potentiodynamic polarization studies in 3.5 wt% sodium chloride solution. The heat treatment temperatures of both the microwave and the conventional furnace annealing were kept at regular intervals to study the corrosion performance of the coatings. Microwave heat treatment significantly improved the corrosion performance of the coatings. Further, corrosion mechanisms of as-coated, various microwave- and conventional heat-treated coatings were discussed for the consideration of phase constituents, grain sizes and microstrain.

The anticorrosion properties of paints containing mixed metal oxide-based pigments were examined. Spinels with the cation combinations Ti-Zn-Mg or Fe-Zn-Mg were synthesized. Core-shell pigments with zinc oxide and magnesium oxide layers were also prepared. The pigments were synthesized from the oxides or carbonates by the high-temperature solid-phase process. The anticorrosion and physico-mechanical properties of film of paints based on an alkyd resin modified with soy oil and containing the pigments at a volume concentration of 10% were investigated. The highest anticorrosion efficiency was observed with the ferrite-based pigments. The anticorrosion efficiency was found to increase with increasing Zn contents of the pigments.