Biomedical corrosion
The majority of metals and alloys used to manufacture implants—stainless steel, cobalt chromium, and titanium alloys—have been used for decades and are therefore regarded safe to use in human body. However, while functioning in vivo in the relatively aggressive environment of the human body, metals are subjected to various corrosion, tribocorrosion, and wear processes. Generally termed biocorrosion or biomedical corrosion, these mechanisms can lead to the release of various degradation products, such as metal ions or particles, into an implant’s surroundings. Understanding these mechanisms will increase our confidence in choosing proper materials for particular devices and designing them in such a way to greatly withstand the long-term degradation process in the human body.
“Editorial: Biocorrosion Special Issue”
The Guest Editor for the Biocorrosion special issue provides an overview to the topic of biocorrosion, and briefly summarizes each of the articles in the special issue.
“Investigation of the Repassivation Process of CoCrMo in Simulated Biological Fluids”
Researchers sought to determine the effect of simulated bodily fluids on metal-on-metal joints that are designed for long-term use in the body. They found that the presence of a certain protein in the fluid led to an increase in the amount of molybdenum released from the alloy.
“Effects of Minor Sr Addition on Biocorrosion and Stress Corrosion Cracking of As-Cast Mg-4Zn Alloys”
Addition of strontium was found to reduce the corrosion rate and improve the strength of a magnesium-zinc alloy in simulated body fluids.
“Corrosion Properties of a Low-Nickel Austenitic Porous Stainless Steel in Simulated Body Fluids”
This study evaluates a novel low-nickel stainless steel in two typical simulated body fluids, finding that it had better corrosion resistance than 316LN.
“Grain Boundary Assisted Crevice Corrosion in CoCrMo Alloys”
This work extends the understanding of chromium depleted zones in cobalt chromium molybdenum alloys, widely used in implantable biomedical materials for hip replacements, and their role in corrosion to the nanoscale. Nanoscale regions of chromium depletion were found to have significant effects on corrosion initiation.
“Corrosion and Passivity of Ti-13% Nb-13% Zr in Comparison to Other Biomedical Implant Alloys”
Variations of a titanium-based implant alloy were tested in simulated environments and evaluated for their passivity and corrosion resistance.
“Pitting Resistance of New and Conventional Orthopedic Implant Materials—Effect of Metallurgical Condition”
Evaluating two of the most widely used alloys in implants at the time, this study found that transformation induced plasticity (TRIP) steels were potential candidates for future implants, pending further corrosion testing.
“In Vitro Evaluation of Degradation of a Calcium Phosphate Coating on a Mg-Zn-Ca Alloy in a Physiological Environment"
This study explores whether a calcium phosphate coating could enhance the corrosion resistance of a magnesium alloy to make it more suitable to use for biodegradable temporary implants. The coating was found to significantly decrease the degradation rate of the magnesium alloy.
“Development of an Artificial Saliva Solution for Studying the Corrosion Behavior of Dental Alloys”
In an effort to better test dental alloys’ corrosion behavior, researchers developed a new artificial saliva. Tests showed electrochemical behavior similar to that obtained in natural saliva.
