Liberation and Separation of Ultrafine Tungsten Carbide Particles from an Activated Carbon Substrate

Abstract

Production of fine-grained tungsten carbide is expensive due to the energy-intensive techniques employed in traditional commercial operations. Recent research has shown that ultrafine (<2 μm) tungsten carbide particles can be produced by the adsorption of tungstate oxyanions on an activated carbon substrate followed by reduction and carburization at elevated temperature under a controlled furnace atmosphere. The thermal processing step is effective at temperatures substantially lower than those used in commercial practice. However, the carbide particles remain bonded to the surfaces of the larger carbon particles. Liberation and separation of the carbide particles have proved challenging, and the literature suggests that comminution and classification at this scale have not been thoroughly investigated. This paper describes the development of a highly effective method for liberation, separation, and purification of ultrafine tungsten carbide particles. It is paramount to note that to maintain the energy efficiency of the technique and to avoid any unwanted changes to size and shape and also to avoid the agglomeration of WC particles due to heat, any techniques that could have introduced a significant amount of heat during liberation and separation of WC particles had to be avoided. This resulted in the elimination of techniques such as burning off the activated carbon substrate or any exothermic chemical reactions, which posed another significant challenge on the liberation and separation of WC particles. Taken together, physical liberation (ball milling) and separation (centrifugation) were proved to be highly effective to achieve the aforementioned goals.

Mathematical Approximation for Quantifying Noise Level in Silicon- and Nonsilicon-Based Chips for DNA Detection

“…In electrophysiological systems, noise is characterized as any disturbance that hinders the accurate measurement of the signal, causing it to deviate from its true measured value. 7 Within these systems, signal disruptions may arise from various sources, including acoustic and electromagnetic interference present in the laboratory environment where experiments are con-ducted�classified as external sources. Additionally, the amplifier itself can introduce disturbances in the form of electromagnetic waves, which constitute internal noise.…”

“…However, in contrast to biological nanopores, solid-state nanopores offer the advantage of facilitating the fabrication of robust nanopores . Previous research has demonstrated the considerable challenge in separating and characterizing inorganic particles <2 μm, primarily due to limitations posed by particle density and centrifugation methods . It is noteworthy that, for instance, the centrifugation process can lead to the breakage and fragmentation of delicate DNA polymer molecules .…”

“…6 Previous research has demonstrated the considerable challenge in separating and characterizing inorganic particles <2 μm, primarily due to limitations posed by particle density and centrifugation methods. 7 It is noteworthy that, for instance, the centrifugation process can lead to the breakage and fragmentation of delicate DNA polymer molecules. 8 Consequently, the adoption of nondestructive DNA detection techniques holds significant promise for enhancing the efficacy of DNA analysis procedures.…”