Details

Autor(en) / Beteiligte

• Aladesuyi, Olanrewaju
• Pal, Mousumi
• Emetere, Eterigho Moses
• Das, Swapan Kumar
• Ajanaku, Kolawole Oluseyi
• Gupta, Manoj

Titel

Influence of transition metal ion (mn4+) on mullite formation in a mixture of 50:50 Nigerian kaolin and calcined alumina

Ist Teil von

• Cogent engineering, 2017-01, Vol.4 (1), p.1396947

Ort / Verlag

Abingdon: Cogent

Erscheinungsjahr

2017

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• In the present investigation, 5 wt% chemical grade MnO 2 was added in a mixture of 50:50 Nigerian sources of kaolin and superfine calcined alumina powder and effect of this transition metal ion on their physico-mechanical properties, phase and microstructural evolution were studied during heating in the temperature range of 1,400-1,650°C. The heated samples were found to be highly porous (>30%) in this entire temperature range. The doping of 5 wt% MnO 2 in this mixture did not improved the densification, but resulted into higher flexural strength (26 MPa) at 1,400°C compared to 7 MPa in the undoped sample. At 1,650°C, the reverse trend was observed, the flexural strength of undoped sample was found to be higher (38 MPa) than doped sample (27 MPa). The XRD study revealed the formation of mullite as major and corundum as minor phases in both the samples. The microstructural study shown the presence of needle shaped mullite crystals and corundum grains. The presence of inter-granular and intra-granular pores in MnO 2 doped samples might have reduced the strength at 1,650°C. The aspect ratio of mullite needle at 1,650°C was found to be higher in doped sample. The theoretical and experimental value of >4 for MnO 2 ion has been validated.