The Corrosion Resistance of Aluminum–Bronze Coatings as a Function of Gas Pressure Used in the Thermal Spraying Process

Alfredo Morales,Oscar Piamba,Jhon Olaya

doi:10.3390/coatings9080507

Abstract

We report the results of the influence of acetylene and oxygen gas pressure on the corrosion resistance of bronze–aluminum coatings deposited on a naval brass substrate by means of the thermal (flame) deposition process. The coatings were characterized by means of scanning electronic microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), X-ray fluorescence (XRF), and transmission electron microscopy (TEM). The corrosion tests were carried out via Tafel and electrochemical impedance spectroscopy (EIS). In addition, some samples were selected in order to investigate heat treatment and its effects on corrosion resistance. The results indicate that changes in the pressure and flow of the gas affects the composition, morphology, and physical properties of the coatings, and these effects have consequences for the behavior of the coatings when they are immersed in corrosion environments. The collision speed of the particles was identified as the most significant factor that influences the properties and the performance of the coating. The gas pressure modified the oxides and the porosity level, which improved the corrosion resistance.

Highlights

In industry, there is a need to improve the processes of protection and repair of naval, automotive, and aeronautical components
The behavior observed for the velocities is consistent with the expected behavior for subsonic gas flows, in which the increase in velocity is a consequence of the increase in the flow rates of the gases through a constant section and the addition of heat generated during the combustion reaction
The behavior observed for the velocities is consistent with the expected behavior5 of for subsonic gas flows, in which the increase in velocity is a consequence of the increase in the flow rates of the gases through a constant section and the addition of heat generated during the combustion matrix rich in theitαcan phase andthat the the presence of the β ‘(Cu κ1

Summary

Introduction

There is a need to improve the processes of protection and repair of naval, automotive, and aeronautical components. In order to reduce the corrosion rate of these components, the application of protective coatings using thermal spraying is a strategy that has undergone rapid development in recent years These techniques seek to extend the useful life of the components in the face of the difficulties of fabrication and the rise in price of the components in the replacement process. An economical and efficient alternative for protecting these components is the use of flame spraying For this purpose, an aluminum–bronze alloy can be used, which is a good alternative for replacing parts subjected to corrosive environments [1] and which has a chemical composition very similar to that exhibited by the components that are used in the transportation industry

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