Synthesis and Characterization of Mechanically Alloyed, Nanostructured Cubic MoW Carbide

Martin Martinez Ruiz,Leonardo González Reyes,Jesus Garcia Martinez,Rodolfo Morales Davila,Vicente Garibay Febles,Lucía G Diaz Barriga Arceo,Jesús Noé Rivera Olvera

doi:10.3390/app10249114

Abstract

Carbides are used extensively as cutting tools, forming dies, and recently in catalysis applications, among other industrial applications. In this work, the synthesis and characterization of a nanostructured MoW bimetallic carbide were carried out by mechanical alloying with a mixture of elemental powders with a nominal composition of W1.5Mo6C2.5 at different grinding times as follows: 25, 50, and 75 h in a low-energy ball mill at a speed of 500 rpm and 125 and 150 h in a high-energy ball mill at a speed of 1500 rpm. The formation of a solid solution was observed at 150 h of milling; the nanostructured bcc MoW carbide corresponded to the main phase in the sample, besides the presence of the nanostructured MoW alloy as a secondary phase with an average crystal size of 40.8 nm. The phases and morphology at every stage of milling were studied by: X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Vickers hardness. As the milling time increased, the hardness of these particles increased from 10.5 to 31.48 GPa for the powder particles milled for 150 h. The samples obtained at 125 and 150 h of milling were evaluated during catalytic aqua-thermolysis of heavy oil to analyze fuel desulfurization properties by Fourier transform infrared (FTIR) techniques. The results showed the breaking of S-S bonds, indicating the existence of a desulfurization reaction of heavy oil.

Highlights

Over the last few years, there has been increasing interest in the exploration of production methods for nanostructured materials because their physical properties change as the crystallite particle size decreases
By increasing the milling time, all the peaks decreased; this is related to the microstructural refinement and the formation of crystallographic defects caused by mechanical impacts during the mechanical alloying (MA) process
The microstructural evolution sequence of the phase against milling time was: C + W + Mo → C + WMo → (WMo)C. We proposed that this phase (MoWC) showed a bcc crystalline structure like MoW system; this agreed with the experimental method proposed by Suryanarayana for the determination of crystalline structures of cubic type, which explains that the correct Bravais lattice can be determined following the sequence of the typical reflections associated with the cubic lattice [26] from the relation: sin2 θ =

Summary

Introduction

Over the last few years, there has been increasing interest in the exploration of production methods for nanostructured materials because their physical properties change as the crystallite particle size decreases. The presence of carbon yields excellent mechanical and catalytic properties, mainly when the carbon is mixed or used to support transition metals [1,2,3]. An example of these kinds of materials is NiW, MoW, and NiMoW phases, which have. Sci. 2020, 10, 9114 attracted attention by the petrochemical industry due to their applications as catalysts in extra-heavy desulfurization crudes. These systems are cheaper than other catalysts for the same purpose [4]

Methods

Results

Conclusion