Novel mullite‐cordierite ceramic refractory fabricated from halloysite and talc

Cordierite ceramic was fabricated by reducing Al2O3 mole ratio from 2.0 to 1.4 with kaolin, silicon dioxide and magnesium oxide as the raw materials. The effect of reduced Al2O3 mole ratio on the sintering behaviors, phase transition, main properties, and microstructure were characterized in detail. The results show that cordierite phase becomes the main crystallization phase at 1300?C, and mullite phase can be consumed to produce cordierite phase by reducing Al2O3 mole ratio. But additional quartz phase still exists until 1400?C. Moreover, the open porosity, pore connectivity and pore size increase as Al2O3 mole ratio reduces from 2.0 to 1.4 while the linear shrinkage percent and bulk density decrease with the reduced Al2O3. It is considered that the sintering activity of the raw materials at low temperature decreases due to the increase of chemically pure magnesium oxide and silica with the decrease of Al2O3 mole ratio, while the crystallization process, pore growth and cordierite phase rather than the liquid phase control the densification process at high temperature.

Download Full-text

Quantitative Evaluation of Crystalline and Amorphous Phases in Clay-Based Cordierite Ceramic

Minerals ◽

10.3390/min10121122 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1122

Author(s):

Zdeněk Klika ◽

Marta Valášková ◽

Lucie Bartoňová ◽

Petra Maierová

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Chemical Analysis ◽

Test Results ◽

Mineral Analysis ◽

X Ray Diffraction ◽

X Ray ◽

Amorphous Phases ◽

Cordierite Ceramic ◽

Scanning Electron

An innovative chemical quantitative mineral analysis (CQMA) was successfully tested on a cordierite-based clay ceramic sample to quantify crystalline and amorphous components. The accuracy of this method was demonstrated on an added module to the CQMA program that used oxide formulas of amorphous phases obtained by energy dispersive X-ray spectroscopy (EDS) microprobe chemical analysis. This CQMA method was tested for three variants calculated using chemical analysis, i.e., X-ray diffraction (XRD) identification of crystalline (cordierite and enstatite) and amorphous phases by scanning electron microscopy (SEM)/EDS texture and microanalyses. The test results from CQMA suggest their application possibilities as well as the limits of their utilization.

Download Full-text

Fractographic Investigations of Ordinary Ceramic Refractory Materials with Reduced Brittleness

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.409.209 ◽

2009 ◽

Vol 409 ◽

pp. 209-215 ◽

Cited By ~ 5

Author(s):

Harald Harmuth ◽

Christian Manhart

Keyword(s):

Correlation Length ◽

Strain Energy ◽

Crack Path ◽

Elastic Strain Energy ◽

Maximum Load ◽

Refractory Materials ◽

Group Of Seven ◽

Large Size ◽

Surface Profiles ◽

Ceramic Refractory

A fractographic procedure was developed and applied for ordinary ceramic refractory materials with a rather large size of heterogeneities and defects. It is based on a stereooptical method for generation of digital surface profiles which are evaluated by an autocorrelation function. Furthermore, a lateral correlation length is derived. A group of seven refractory materials was characterised by mechanical and fracture mechanical investigations, and the same specimens had been characterized by the fractographic procedure. Correlations have been tested. The results show a relation between the lateral correlation length and two fracture mechanical characteristics which are significant for the material brittleness and the elastic strain energy stored at maximum load. These relations are contributed to the dependence of the crack path on brittleness. With decreasing brittleness the amount of the crack path proceeding along the grain/matrix boundary increases for the materials investigated.

Download Full-text