Preparation and characterization of porous anorthite ceramics from red mud and fly ash

Abstract

The porous anorthite ceramics with high porosity, good mechanical strength and low heat conductivity were prepared using red mud and fly ash as raw materials via the pore forming method. The effects of sintering temperature and fly ash on phase evolution, densification, compressive strength, thermal conductivity and microstructure of the ceramic materials were investigated. The results showed that the compressive strength of the porous ceramics had an obvious improvement with the increase in fly ash, and the densification and heat conductivity decreased firstly and then increased. In particular, specimen S2 containing 30 wt% red mud and 40 wt% fly ash sintered at 1150°C had the better performances. It had the water absorption of 18.18%, open porosity of 38.52%, bulk density of 1.29 g/cm 3 , compressive strength of 42.46 MPa, and heat conductivity of 1.24 W/m·K. X-ray diffraction analysis indicated that mullite, anorthite, α-quartz, and diopside ferrian were the dominant phases in the specimens. Scanning electron microscopy micrographs illustrated that plenty of open pores with strip shape and closed pores with axiolitic shape existed in the specimens. Furthermore, the existence of mullite could prevent crack propagation to enhance the energy of inter-granular fracture.It endowed the porous anorthite ceramics with high porosity, good compressive strength, and low heat conductivity. K E Y W O R D Scompressive strength, densification, fly ash, porous ceramics, red mud, thermal conductivity

Porous cenosphere ceramic microfiltration membrane: Preparation, characterization, permeability evaluation, and cost estimation

“…This loss may be related to the loss from crystallized water, the release of carbon dioxide from the breakdown of carbonate additives, or even the residual carbon particles left over during combustion. [13,22] Decomposition was the primary cause of CO 2 emission in the 650-700 C temperature range, which also contributed in the creation of open spaces and a porous membrane structure. After 650 C, there was barely any weight loss.…”

“…With the membrane, a high permeability of 450 Lm −2 h −1 bar −1 was achieved. [ 12 ] Xiang and Ding [ 13 ] were also able to produce porous anorthite ceramics by using alternate raw materials such as red mud and fly ash, which provided high porosity, strong mechanical strength, and low heat conductivity. Coal fly ash was employed by Chen et al [ 14 ] to produce inexpensive ceramic membranes.…”

Photocatalytic properties of ZnO nanoparticle coating on porous ceramic substrates with varying porosities produced from fly ash and red mud

“…On the other hand, ceramicization at high temperatures produces ceramics with a stable crystalline structure, low permeability, and the ability to prevent the ingress of pollutants, allowing their breakdown through photocatalysis. The combination of ceramicization and subsequent coating with ZnO nanoparticles enhances the mechanical strength, thermal stability, and chemical resistance of RM and FA‐derived ceramics, making them effective and durable for photocatalytic applications in challenging environments, where they can efficiently degrade organic pollutants upon exposure to ultraviolet light 21,44–49 …”

“…The combination of ceramicization and subsequent coating with ZnO nanoparticles enhances the mechanical strength, thermal stability, and chemical resistance of RM and FA-derived ceramics, making them effective and durable for photocatalytic applications in challenging environments, where they can efficiently degrade organic pollutants upon exposure to ultraviolet light. 21,[44][45][46][47][48][49] With yearly output surpassing hundreds of millions of tons, the hazardous by-products FA and RM pose a significant environmental risk. Due to the porous and fine particle structure of RM, it is possible to create a ceramic system with both FA and RM.…”

Nonstandard Raw Materials for Anorthite Ceramics Production

“…Учеными [4] исследовалась возможность изготовления анортитовой керамики, обладающей высокой пористостью, механической прочностью и низкой теплопроводностью. Исследовано влияние температуры спекания и количество летучей золы на уплотнение, прочность при сжатии, теплопроводность и микроструктуру керамических материалов.…”