The effect of the saliva formulation on brass corrosion

Abstract

The composition of natural saliva is strongly variable and unstable outside the oral cavity, therefore corrosion tests are usually performed in artificial saliva solutions. In this study the effect of the composition of various saliva solutions on the corrosion behavior of a CuZn37 alloy, exposed for 1, 3, and 16 h to the solutions, is investigated by using electrochemical measurements, optical microscopy, and X-ray photoelectron spectroscopy (XPS). The solutions investigated in this study are: Darvell, Carter-Brugirard, and SALMO, selected for their composition that mainly differs in the organic compounds' content. Electrochemical measurements show that the open circuit potential and the polarization resistance increase with exposure time in the solutions, indicating a decrease in the corrosion rate. The corrosion rate (µm/year) in the Darvell solution is found to be two times higher than the other artificial saliva formulations and varies in the order: Darvell > Carter-Brugirard > SALMO. These data suggest that the presence of different organic compounds might limit the formation of a stable protective surface film as confirmed by XPS surface analyses.

The role of organic compounds in artificial saliva for corrosion studies: Evidence from X‐ray photoelectron spectroscopy

“…In a recent work of the authors, 6 the corrosion behaviour of CuZn37 exposed to D, C‐B and SALMO formulations was investigated by electrochemical measurements, and it was found that the corrosion rate varied in the order: D > C‐B > SALMO. In this work, the corrosion behaviour can be correlated to the surface composition of the film formed.…”

“…In previous papers, the authors reported that, on brass alloy surfaces following the exposure of the samples to the model saliva solution, a thick surface film composed to a large extent of CuSCN and Zn 3 (PO 4 ) 2 was observed 4,5 . In a recent work, 6 the corrosion behaviour of CuZn37 exposed to Darvell (D), 7 Carter‐Brugirard (C‐B) 8 and SALMO 9 formulations was investigated by electrochemical measurements, and it was found that the corrosion rate determined after 16 h varies in the order: D (3.0 (0.3) μm/year) > C‐B (0.9 (0.2) μm/year) > SALMO (0.8 (0.2) μm/year). These three model saliva solutions were chosen from those of the literature due to their composition: All of them contain chlorides, thiocyanates, phosphates and carbonates, but they differ for the content in the organic compounds: D solution contains urea, lactic acid, trisodium citrate and uric acid; SALMO solution contains urea and glycine; C‐B solution contains only urea.…”

Surface Chemistry of Passive Films on Ni-Free Stainless Steel: The Effect of Organic Components in Artificial Saliva

“…Citrate ions favored zinc dissolution, limiting the precipitation of the protective zinc phosphate layer. 11,12 In this paper, the effect of three artificial saliva formulations differing in the content of organic compounds on the corrosion resistance of the Ni-free DIN 1.4456 stainless steel is investigated. In fact, due to the widespread occurrence of nickel allergy, the European Commission prohibited the use of products with a Ni release higher than 0.5 μg/cm 2 per week.…”

“…It was demonstrated that when citrate was present, the thickness of the passive layer decreased, and the chromium and molybdenum oxide content in the passive film was higher than in the purely inorganic Hanks’ solution . In the framework of a project devoted to investigate the corrosion of brass wind instruments, the corrosion behavior of brass in different solutions simulating artificial saliva was studied, − and it was shown that the presence of organic ligands in the formulation affects the corrosion rate, thickness, and composition of the surface film formed upon exposure of the brass to the solutions. Citrate ions favored zinc dissolution, limiting the precipitation of the protective zinc phosphate layer. , In this paper, the effect of three artificial saliva formulations differing in the content of organic compounds on the corrosion resistance of the Ni-free DIN 1.4456 stainless steel is investigated.…”

“…In the framework of a project devoted to investigate the corrosion of brass wind instruments, the corrosion behavior of brass in different solutions simulating artificial saliva was studied, − and it was shown that the presence of organic ligands in the formulation affects the corrosion rate, thickness, and composition of the surface film formed upon exposure of the brass to the solutions. Citrate ions favored zinc dissolution, limiting the precipitation of the protective zinc phosphate layer. , In this paper, the effect of three artificial saliva formulations differing in the content of organic compounds on the corrosion resistance of the Ni-free DIN 1.4456 stainless steel is investigated. In fact, due to the widespread occurrence of nickel allergy, the European Commission prohibited the use of products with a Ni release higher than 0.5 μg/cm 2 per week .…”