Avaliação microestrutural e da resistência ao desgaste abrasivo de revestimentos produzidos pelas técnicas HP-HVOF e Flame Spray em substrato de aço-carbono (AISI 1020)

Abstract

The present study aimed at the microstructural characterization and evaluation of abrasive wear resistance of the following industrial coatings (with and without NbC addition) deposited on AISI 1020 carbon steel substrate by HP-HVOF and Flame Spray techniques: Metco 16C®+25wt.-%NbC (without and with melting), Metco 16C®+wt.-%25SiC (without and with melting), Metco 16C®+30wt.-%Basalt (without and with melting), tungsten carbide, tungsten carbide+30wt.-%NbC, chromium carbide, chromium carbide+30wt.-%NbC, Orgrabor®, Stellite, Inconel 625 and niobium oxide.The microstructural characterization of coatings was carried out by means of X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The hardness and abrasive wear tests were performed on polished surfaces of coatings. Thepresentphases in microstructures of coatings were determined with relative successfully by EDS analysis due to its limitation for quantify the light elements presents in some phases. Abrasivewear resistance of coatings was increased in the sequence: niobium oxide (lower resistance), Inconel 625, Metco 16C®+30wt.-%Basalt (without melting), Metco 16C®+25wt.-%SiC (without melting), Metco 16C®+25wt.-%NbC (melting), Metco 16C®+25wt.-%NbC (without melting), Stellite, chromium carbide, Metco 16C®+30wt.-%Basalt (melting), Metco 16C®+25wt.-%SiC (melting), tungsten carbide+30wt-%NbC, chromium carbide+30wt.-%NbC and tungsten carbide (higher resistance). Results have indicated that depending on coating composition the NbC addition can contribute to maintainappreciable levels of abrasive wear resistance for lower production costs.