Effect of the Surface Chemical Composition on the Corrosion Resistance in the Mixture of FeCrMoNbB (140MXC) and FeCMnSi (530AS) Coatings Produced with the Electric Wire Arc Spraying Technique: Part I.

Abstract

In this study, FeCrMoNbB (140MXC) and FeCMnSi (530AS) coatings were simultaneously projected on the substrate AISI-SAE 4340 using the electric wire arc spraying technique. The projection parameters, such as current (I), voltage (V), primary air pressure (1st), and secondary air pressure (2nd), were determined using the experimental model Taguchi L9 (34-2). Its main purpose is to produce dissimilar coatings and to evaluate the effect of the surface chemical composition on the corrosion resistance in the mixture of 140MXC-530AS as commercial coatings. Three phases were considered to obtain and characterize the coatings: Phase 1: Preparation of materials and projection equipment; Phase 2: Coatings production; and Phase 3: Coatings characterization. The characterization of the dissimilar coatings was carried out using the techniques of Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX), Auger Electronic Spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The results of this characterization corroborated the electrochemical behavior of the coatings. The presence of B was determined with the XPS characterization technique in the mixtures of the coatings in the form of Iron Boride. Moreover, the XRD technique showed Nb in the form of FeNb as a precursor compound for the 140MXC wire powder. The most relevant contributions are the pressures, provided that the quantity of oxides in the coatings decreases with respect to the reaction time between the molten particles and the atmosphere of the projection hood; moreover, for the corrosion potential, the operating voltage of the equipment does not exert any effect since these tend to remain constant.