Effect of Boron on Microstructure and Microhardness Properties of Mo-Si-B Based Coatings Produced Via TIG Process

Abstract

In this study, Mo-Si-B based coatings were produced using tungsten inert gas (TIG) process on the medium carbon steel because the physical, chemical, and mechanical properties of these alloys are particularly favourable for high-temperature structural applications. It is aimed to investigate of microstructure and microhardness properties of Mo-Si-B based coatings. Optical microscopy (OM), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the microstructures of Mo-Si-B based coatings. The XRD results showed that microstructure of Mo–Si–B coating consists of α-Mo, α-Fe, Mo2B, Mo3Si and Mo5SiB2 phases. It was reported that the grains in the microstructure were finer with increasing amounts of boron which caused to occur phase precipitations in the grain boundary. Besides, the average microhardness of coatings changed between 735 HV0.3 and 1140 HV0.3 depending on boron content.

Quantitative analysis of Mo–Si–B alloy phases with wavelength dispersive spectroscopy (WDS–SEM)

“…However, these alloys show a lack of oxidation resistance in the intermediate temperature range, 650–750 °C, and possess a relatively high density (9.6 g/cm 3 ) compared to nickel‐based Superalloys . Islak et al quantified the molybdenum and boron content of Mo–Si–B based coatings, which are similar to the alloys used in this work, by energy dispersive X‐ray spectroscopy (EDS). The characterization of these alloys, especially the Mo 5 SiB 2 phase, with a scanning electron microscope (SEM) with X‐ray microanalysis analytical capabilities is a real challenge.…”

INFLUENCE OF ZrB2 ADDITION ON MICROSTRUCTURAL DEVELOPMENT AND MICROHARDNESS OF Ti-SiC CLAD COATINGS ON Ti6Al4V SUBSTRATE

“…It has been reported that Ti-Si-C-B containing coatings proffer integral excellent properties, produce unique ceramic phases of increased hardness values with several strengthening influence as a result of the enormous attraction among these elements [19][20][21]. The presence of Boron in coatings can refine the microstructure [22] and also increase the melting efficiency of hard SiC particles owing to the presence of a eutectic phase at 3.6 %B [11].…”