High-Strength Solidification of Fly Ash/Carbide Slag and Its Fixing Ability for Heavy Metals

Song, Huiyu; Wei, Lifang; Ji, Yinglu; Cheng, Fangqin

doi:10.12783/issn.1544-8053/14/1/19

Cited by 2 publications

(1 citation statement)

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“…Their approach was to apply HHP to finely ground powder followed by foaming at 600 °C, resulting in a low thermal conductivity of 0.21W (m K) –1 . More recently, in 2005 Xue et al [116] and later on Song et al [117], employed HHP (45 min and 7 MPa at 200 °C) as a sustainable method for immobilising heavy metal ions, with a good fixation effect on metals such as Cu, Zn, Cd and Pb within an inert matrix derived from fly ash. Using waste glass from TV screens, preparation of porous glass with low thermal conductivity (0.2 W (m K) –1 ) [118] was achieved by HHP followed by foaming (induced by entrapped water) at 750 °C for 1 h. A similar approach was also applied to other systems resulting in a final density as low as 0.40 g cm –3 obtained for SiO 2 ( α -cristobalite and quartz) and CaSiO 3 (wollastonite) [119].…”

Section: Recent Developments In Near Room Temperature Consolidation: ...mentioning

confidence: 99%

A review of cold sintering processes

Grasso

Biesuz

Zoli

et al. 2020

Advances in Applied Ceramics

183

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The need to reduce the energy consumed and the carbon footprint generated by firing ceramics has stimulated research to develop consolidation techniques operating at lower temperatures, ideally not exceeding 300°C. This has been realised in Ultra Low Energy Sintering (ULES) using high pressure (hundreds of MPa) in the presence of a transient liquid phase, which accelerates plasticity, grain boundary/surface diffusion and mass transport. Several ULES techniques have been developed in the past 50 years, and a common feature of all of them is low temperature consolidation, through mechanisms not yet fully understood, enabling multi-material integration (e.g. organics and inorganics). This research could transform the traditional firing of functional and structural materials. Early stage work on ULES, started in the 1960s, clearly demonstrated cohesion between the compacted particles exceeding what was possible if simply produced by Van der Waals bonding, suggesting the formation of primary inter-particle bonds. Surprisingly, metals Cold Sintered (CS) in dry conditions at room temperature can be even stronger than their counterparts sintered at high temperatures (typically ≈ 2/3 T m). Hydrothermal Hot Pressing (HHP) was originally conceived in the context of sustainability and environmental preservation, with some examples being the concept of 'synthetic rock' for immobilisation of toxic/radioactive waste and the consolidation of high surface area porous ceramics for filtration. Follow up work on HHP considered the possibility of recreating in the lab bio-mineralisation using hydroxyapatite and bioglass (including hybrids) as proof of concept. Recent work on the Cold Sintering Process has demonstrated the potential to bridge the processing gap of multimaterial devices (sensors, batteries, 5G antennas, electronic components and biomaterials), enabling integration of polymers, ceramics and metals without degradation of the individual components both at the bulk and interface level. The absence of heating unlocks grain boundary design to an unprecedented level, offering further degrees of freedom in tuning functional properties. This review provides a wide perspective on room temperature consolidation, and covers the related but fragmented work published (≈ 450 papers) during the past 50 years, encompassing the relevant work developed in different disciplines including chemistry, physics, biology and geoscience. Liquid-assisted or liquid-mediated phenomena involving diffusion, plasticity, rheology, and grain growth are still largely unexplored in material science. The purpose of bringing together this literature is to build a general and multidisciplinary knowledge to guide future research directions. Both the reduction of energy consumption and carbon footprint are driving the growing interest in ULES, which could reinvent the concept of sintering, 'rendering kilns obsolete'. Also, ULES has the potential to produce new classes of materials that cannot be fabricated using conventional routes.

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Section: Recent Developments In Near Room Temperature Consolidation: ...mentioning

confidence: 99%