Corrosion Properties of Electroplated CoNiFe Films

Abstract

Electroplated CoNiFe films with a saturation flux density as high as 2.1 T are potentially useful in high‐density magnetic recording heads. We found that films electroplated at a high current density false(15 normalmA/cm2false) from a bath without saccharin have a sufficient anodic pitting‐corrosion potential (−65 mV). We also found that the pitting‐corrosion potential of films electroplated under a low current density false(5 normalmA/cm2false) from saccharin‐free baths have anodic pitting‐corrosion potentials of less than −300 mV. However, the corrosion resistance improved after annealing at temperatures above 100°C. The crystal‐grain boundaries in the as‐plated film that electroplated under a low current density from saccharin‐free baths are not clear (i.e., that the phase is amorphous). But the crystal grain boundaries in the annealed film are clear. Films electroplated from baths containing saccharin also have anodic pitting‐corrosion potentials of less than −300 mV. Their corrosion resistance did not improve when they were annealed at 250°C. The deterioration of the corrosion resistance is attributed to the defects that increase the face‐centered cubic (111) lattice constant. One of the most important characteristics of a highly corrosion‐resistant CoNiFe film is fine crystal structure with very few defects. © 1999 The Electrochemical Society. All rights reserved.

Nanoscale Topography on Black Titanium Imparts Multi-biofunctional Properties for Orthopedic Applications

“…The corrosion rate for the control titanium surface determined from the Tafel plot was found to be 3.1 × 10 −6  mA/cm 2 whereas the corrosion rate for the black titanium was 6.3 × 10 −5  mA/cm 2 (Figure S8). Although the current density observed on the black titanium surface displayed one-fold increase over that of the control, both these values are lower than that of other metallic materials3839. Thus, the black titanium exhibits good corrosion resistance and is well suited for use as a biomaterial.…”

Electrodeposited Iron Group Thin-Film Alloys: Structure-Property Relationships

“…9,10 Saito et al investigated electrodeposited CoNiFe and found that pitting potentials shifted to more negative potentials with increasing saccharin concentration. 11 The corrosion behavior was also affected by deposition parameters and can be improved by reducing grain size. 11 Even though there are many studies on electrodeposited irongroup alloys, there is a lack of systematic studies relating properties of electrodeposited iron group thin films including NiFe, CoNi, CoFe, and their ternary alloys with deposit composition, grain size, and crystal structure.…”

Effects of impurities on resistivity of electrodeposited high-B/sub s/ CoNiFe-based soft magnetic thin films

“…At the same time, however, such inclusion might affect the corrosion resistance of the film as observed in CoNiFeS films [11], [12]. Thus, we also investigated the corrosion resistance of CoNiFeC film in a 2.5-wt% NaCl aqueous solution.…”

“…In addition, it should also be noted that the corrosion resistance of the film is related to its crystallinity. It was reported that the inferior corrosion resistance of amorphous-like CoNiFe film was drastically improved by annealing at 250 C, while that of CoNiFeS film did not and that the annealing led to slight improvement of crystallinity of the former film while defects within the latter film still remained [12]. For the present CoNiFeC film, it was shown from TEM and THEED results, which are omitted here, that the annealing caused an improvement in crystallinity not in grain growth, similar to CoNiFe rather than CoNiFeS.…”