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

Abstract

Several formulations of artificial saliva have been used for corrosion studies. The present work focuses on the effect of different saliva formulations on the composition of the surface film formed on CuZn37 brass alloy by X-ray photoelectron spectroscopy (XPS), in order to clarify the corrosion mechanism of historical brass wind instruments when used. Three different saliva solutions, Darvell (D), Carter-Brugirard (C-B) and SALMO, were selected. They differ for the content of the organic compounds. The XPS results show the presence of a film made of CuSCN and zinc-phosphate on the brass exposed to C-B and SALMO. In the case of samples exposed to D formulation, phosphorus is not revealed, a decrease in the zinc content in the film is detected and the S 2p shows the presence of a second component together with the one ascribed to CuSCN. A comparison with the results obtained on the pure metals in the presence of the organic compounds suggests that the formation of zinc and copper complexes may lead to thin and less protective surface film and thus to the observed high corrosion rates.

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

“…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.…”

“…The three formulations here adopted were as follows: Darvell (D), 17 Carter-Brugirard (C-B), 18 and SALMO, 19 which were previously used also for investigations on brass corrosion. 11,12 The role of organic compounds that may act as ligands is evaluated here for the first time in order to shed light on the corrosion resistance of the steel following contact with solutions simulating more closely the real conditions where the brackets are in contact with biological fluids.…”

“…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 .…”

“…In this work, an analytical approach based on the combination of electrochemical techniques and XPS was exploited for clarifying the effect of the composition of the artificial saliva solution on the corrosion behavior and on the passive film composition of the nickel-free stainless steel. The three formulations here adopted were as follows: Darvell (D), Carter-Brugirard (C-B), and SALMO, which were previously used also for investigations on brass corrosion. , The role of organic compounds that may act as ligands is evaluated here for the first time in order to shed light on the corrosion resistance of the steel following contact with solutions simulating more closely the real conditions where the brackets are in contact with biological fluids.…”

The effect of the saliva formulation on brass corrosion

“…Morphological characterization was carried out by optical microscopy and the films grown on the sample surfaces were characterized by X-ray photoelectron spectroscopy (XPS). [17] 2 | MATERIALS AND METHODS…”