CORROSION BEHAVIOR OF PD-CU AND PD-CO ALLOYS IN SYNTHETIC SALIVA
CORROSION BEHAVIOR OF PD-CU AND PD-CO ALLOYS IN SYNTHETIC SALIVA
复制标题
DOI：
10.1016/s0109-5641(05)80039-9
复制
发表时间：
1990-04-01
期刊：
影响因子：
5
通讯作者：
MAREK, M
中科院分区：
文献类型：
--
作者：
GOEHLICH, V;MAREK, M
钯基合金是 PFM 应用中金基合金的主要替代品。在模拟口腔液的电解质中，这些合金表现出类似于活性金属钝化的电极行为，即电流密度几乎恒定的电位区域直至临界电位，高于该临界电位电流增加。本研究的目的是将电极行为与溶液分析结果和合金表面成分的变化联系起来。对二元合金 Pd15 wt% Cu 和 Pd-19 wt% Co 以及纯组分进行了检查。使用合成唾液作为电解质来测量腐蚀电位与时间的关系、动电位阳极极化曲线、极化电阻与时间的关系以及恒电位的绝对电荷。通过原子吸收测定不同暴露后溶液中 Pd、Cu 和 Co 的浓度。在暴露之前和之后通过X射线光电子能谱检查合金的表面。结果表明，在所有暴露情况下，两种合金的表面都发生了次贵金属成分的选择性溶解，使得表面高度富集 Pd。这种丰富导致了潜在的变化和被动型行为。尽管铜的惰性更高，但在较长的暴露时间和较高的电势下，铜比钴溶解得更多。钴的溶解似乎受到表面膜形成的限制，这可能与该元素的过渡特性有关。
Pd-based alloys are major alternatives to gold-based alloys for PFM applications. In electrolytes simulating oral fluids, these alloys exhibit electrode behavior similar to passivity of active metals, i.e., a potential region of almost constant current density up to a critical potential, above which the current increases. The objective of this study was to correlate the electrode behavior with the results of solution analyses and changes in the surface composition of the alloys. Binary alloys Pd15 wt% Cu and Pd-19 wt% Co, as well as the pure components, were examined. Corrosion potentials vs. time, potentiodynamic anoidic polarization curves, polarization resistances vs time, and potentiostatic apodic charges were measured with synthetic saliva used as the electrolyte. The concentrations of Pd, Cu, and Co in the solution after various exposures were determined by atomic absorption. The surfaces of the alloys were examined by x-ray photoelectron spectroscopy before and after the exposures. The results show that selective dissolution of the less-noble components occurred on the surfaces of both alloys for all the exposures, leaving the surfaces highly enriched in Pd. This enrichment contributed to the potential changes and the passive-type behavior. Copper dissolved more than cobalt at longer exposures and higher potentials, in spite of its higher nobility. Dissolution of cobalt seemed to be limited by the formation of a surface film, which may be related to the transition character of this element.