Nanoscale Mechanical Evaluation of Electrochemically Generated Tribolayer on CoCrMo Alloy for Hip Joint Application

Abstract

Cobalt chromium molybdenum alloy (CoCrMo) is widely employed in the orthopedic device industry due to a combination of properties that include low wear, high mechanical strength, and high corrosion resistance. However, when used as the bearing component of total hip implants, this material can be susceptible to wear and corrosion, which can be triggered or exacerbated by factors such as changing pH, biological fluids and cell interactions, particle release, and friction. The physiological fluid, which is composed of electrolytes, proteins, and other organic species, plays a critical role in the tribological behavior of CoCrMo alloy. The aim of this work is to generate a proteinaceous layer electrochemically and carry out nanoscale mechanical and surface evaluation of CoCrMo to understand the feasibility of a pre-treatment on this material. The treatments consisted of electrolytes, with different protein concentrations, and pre-selected transpassive potentials at ?0.6, ?0.7 and ?0.8 V and a passive potential of-0.4 V. These observations will help in determining the electrolyte concentration and potential combination that would yield the most protective film layer. The results demonstrated that all the positive transpassive potentials and electrolyte combinations led to surface degradation processes causing more material removal as seen by the formation of localized corrosion at carbide and grain boundaries. Only the negative potential of-0.4 V, used by itself as a pretreatment and in combination with an electrolyte with 30 g/ L of bovine calf serum (BCS), demonstrated more homogeneous oxide layer and proteinaceous layer distribution respectively. Keywords Cobalt chromium molybdenum Á Tribological behavior Á Transpassive potentials Á Coefficients of friction Á Electrochemical and mechanical degradation Á Third-body particle wear & Danieli C. Rodrigues

Titanium surface bio-functionalization using osteogenic peptides: Surface chemistry, biocompatibility, corrosion and tribocorrosion aspects

“…Hence, the presence of DMP1 peptides enhances the stability of the material during tribocorrosion. The peptides that adhere to the surface can change their nature by transforming into a lubricous material, which protects the surface [62, 63]. Furthermore, the peptides may enhance the hardness and strength of the top surface, resulting in a decrease of the wear rate, besides the lubrication factor [64].…”

Sliding Corrosion Fatigue of Metallic Joint Implants: A Comparative Study of CoCrMo and Ti6Al4V in Simulated Synovial Environments

“…The chemomechanical response illustrated that the reformed chromium oxide layer was not as stable as the original passive layer formed in ambient. During the sliding fatigue on the CoCrMo surface, rapid fluctuations of OCP response illustrated a repetitive process of breakage-reformation cycles of the oxide layer in the PBS [27][28][29]. However, after a dramatic potential drop upon initiating contact stroke, the Ti6Al4V surface presented an increase in potential (positive change).…”

“…In spite of their excellent mechanical and chemical properties, the course of daily motions of the patient and the corrosive synovial fluids surrounding the implant progressively deteriorate the implant surfaces and lead to unexpected failure of the joint. When frictional contact of joint components damages the surface layer during active articulations, the oxide film loses its protection from corrosion attack [27][28][29][30]. Through the damaged surface area, the increased electrochemical potential leads to rapid metal ion dissolution, and reforms the passive layer instantaneously.…”

Progression of Bio-Tribocorrosion in Implant Dentistry

“…The Ti biofunctionalization with proteins and peptides has triggered good results in the initial biological response and also on the material corrosion and degradation resistance (Trino et al, 2018). The peptides immobilized on the Ti surface can act as a lubricous tribolayer which protects the surface (Quiram et al, 2016). Besides, peptides may decrease the wear rate by enhancing the hardness and strength of the top surface .…”