Effect of Imposed Shear Strain on Steel Ring Surfaces during Milling in High-Speed Disintegrator

Abstract

This contribution characterizes the performance of a DESI 11 high-speed disintegrator working on the principle of a pin mill with two opposite counter-rotating rotors. As the ground material, batches of Portland cement featuring 6–7 Mohs scale hardness and containing relatively hard and abrasive compounds with the specific surface areas ranging from 200 to 500 m2/kg, with the step of 50 m2/kg, were used. The character of the ground particles was assessed via scanning electron microscopy and measurement of the absolute/relative increase in their specific surface areas. Detailed characterization of the rotors was performed via recording the thermal imprints, evaluating their wear by 3D optical microscopy, and measuring rotor weight loss after the grinding of constant amounts of cement. The results showed that coarse particles are ground by impacting the front faces of the pins, while finer particles are primarily milled via mutual collisions. Therefore, the coarse particles cause higher abrasion and wear on the rotor pins; after the milling of 20 kg of the 200 m2/kg cement sample, the wear of the rotor reached up to 5% of its original mass and the pins were severely damaged.

Creep and Shrinkage Behaviour of Disintegrated and Non-Disintegrated Cement Mortar

“…There has been a significant amount of research and industrial development in the material processing field to achieve the construction components' longevity, reduce resource consumption and pollution caused by new material production, and reduce waste management costs [1]. These are significant issues in construction businesses because the ordinary Portland cement, considered the main binder material used in construction, is responsible for 5 to 8% of yearly global CO 2 emissions.…”

“…This method is referred to as disintegrator technology, where the material is milled by highly effective high-speed and high-intensity impact in contrast to low-speed impact abrasion [5]. Milling material this way also activates materials that, due to expired shelf life, have lost their ability to create a sufficient bonding effect [1]. One way to verify cement milling results and whether the old cement activity has been regained to the previous level is to assess setting characteristics.…”

Special Issue: Mechanical Properties in Progressive Mechanically Processed Metallic Materials

“…In addition to using the SPD methods based on imposing severe shear strain resulting in grain refinement introducing enhancement of numerous properties, powder metallurgy can be applied to provide powders featuring fine grain sizes at the very beginning of the production process. The paper by K. Dvořák et al [ 4 ] presents the possibility of using modern disintegrators to prepare fine powder particles. Several papers published within the Special Issue then deal with processing of metallic powders—assessing and optimizing the processing conditions and evaluating various phenomena of the final products.…”