Next Article in Journal
High Pressure Pneumatic Forming of Ti-3Al-2.5V Titanium Tubes in a Square Cross-Sectional Die
Next Article in Special Issue
Life Cycle Assessment of Completely Recyclable Concrete
Previous Article in Journal / Special Issue
Material and Structural Performance Evaluations of Hwangtoh Admixtures and Recycled PET Fiber-Added Eco-Friendly Concrete for CO2 Emission Reduction
Article Menu

Export Article

Open AccessArticle
Materials 2014, 7(8), 5982-5991; https://doi.org/10.3390/ma7085982

Recycling of Coal Fly Ash for the Fabrication of Porous Mullite/Alumina Composites

School of Materials Science and Engineering, Pusan National University, Pusan 609-735, Korea
*
Author to whom correspondence should be addressed.
Received: 13 June 2014 / Revised: 11 August 2014 / Accepted: 12 August 2014 / Published: 19 August 2014
(This article belongs to the Special Issue Recycled Materials)
View Full-Text   |   Download PDF [4214 KB, uploaded 19 August 2014]   |  

Abstract

Coal fly ash with the addition of Al2O3 was recycled to produce mullite/alumina composites and the camphene-based freeze casting technique was processed to develop a controlled porous structure with improved mechanical strength. Many rod-shaped mullite crystals, formed by the mullitization of coal fly ash in the presence of enough silicate, melt. After sintering at 1300–1500 °C with the initial solid loadings of 30–50 wt.%, interconnected macro-sized pore channels with nearly circular-shaped cross-sections developed along the macroscopic solidification direction of camphene solvent used in freeze casting and a few micron-sized pores formed in the walls of the pore channels. The macro-pore size of the mullite/alumina composites was in the range 20–25 μm, 18–20 μm and 15–17 μm with reverse dependence on the sintering temperature at 30, 40 and 50 wt.% solid loading, respectively. By increasing initial solid loading and the sintering temperature, the sintered porosity was reduced from 79.8% to 31.2%, resulting in an increase in the compressive strength from 8.2 to 80.4 MPa. View Full-Text
Keywords: coal fly ash; mullite/alumina; camphene; freeze casting; pore channels; compressive strength coal fly ash; mullite/alumina; camphene; freeze casting; pore channels; compressive strength
Figures

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

Share & Cite This Article

MDPI and ACS Style

Kim, K.H.; Yoon, S.Y.; Park, H.C. Recycling of Coal Fly Ash for the Fabrication of Porous Mullite/Alumina Composites. Materials 2014, 7, 5982-5991.

Show more citation formats Show less citations formats

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Materials EISSN 1996-1944 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top