Breakdown corrosion potential of ceramic coated metal implants

Abstract

The long-term success of joint replacement largely depends on the stable fixation of the implant to bone. Current methods rely on mechanical fixation either with or without the use of acrylic bone cement. The drawbacks of cement are well known' and the newer porous metal coatings are still under review.2r3Studies on composites in which metals are coated with ceramics have been reported recently as an alternative method of long-term fixati~n.~" We have devised hydroxyapatite (A) . alumina (B)titanium-nitride (C) (HAP . a-AlZO3 . TiN)-coated SUS-316L stainless steel and HAP (D) . titanium-oxide (E) (TiOJ-coated Ti-6A1-4V.

Degradation characteristics of hydroxyapatite coatings on orthopaedic TiAlV in simulated physiological media investigated by electrochemical impedance spectroscopy

“…Despite the reported similarities between the two systems, some differences can be observed when considering the potential dependence of the passive currents. Whereas a somewhat slow increase of the passivation current is observed for the uncoated specimen as the applied potential is made more positive, the HA-coated specimen shows an increase of this current for almost two orders of magnitude when the potential is set more positive than 1.5 V. This observation could be taken as an indication of an increased metal dissolution in the system through the passive film when the material is coated with hydroxyapatite, as it has been proposed by some authors [23,24]. But increased currents would also occur if the metal dissolves from the metallic substrate and precipitates as hydrated salts on the its surface [25,26], which has been claimed to result in enhanced corrosion resistance of the underlying metal substrate [26].…”

“…But increased currents would also occur if the metal dissolves from the metallic substrate and precipitates as hydrated salts on the its surface [25,26], which has been claimed to result in enhanced corrosion resistance of the underlying metal substrate [26]. Conventional electrochemical techniques do not allow to distinguish between the two cases, and justifies the controversy existing in the scientific literature on whether enhanced or hindered metal ion release occurs for HA-coated Ti-6Al-4V substrates [23][24][25][26].…”

Influence of surface self‐modification in Ringer's solution on the passive behavior of titanium

“…The findings reported in the literature, however, disagree on whether such coatings are beneficial or harmful for the corrosion behavior or, more specifically, to metal-ion release. [21][22][23][24] In the present work, the influence of the surface self-modification by Ca and P ions on the electrochemical behavior was further studied. Passive behavior of commercially pure Ti (cp-Ti) was compared in a simple NaCl solution and in Ringer's solution as a function of exposure time.…”

Preparation and characterization of nano‐CaCO3 encapsulated with polyacrylic and its application in PVC toughness

“…The influence of hydroxyapatite coatings intentionally produced on Ti surfaces (instead of naturally formed Ca‐P precipitate layers) on the corrosion behavior has been studied as well. The findings reported in the literature, however, disagree on whether such coatings are beneficial or harmful for the corrosion behavior or, more specifically, to metal‐ion release 21–24…”