| Title | The Formation of Mullite from Kaolinite under Various Reaction Atmospheres |
| Publication Type | Journal Article |
| Year of Publication | 1996 |
| Authors | Mackenzie, K.J.D., Meinhold R.H., Brown I.W.M., and White G.V. |
| Journal | Journal of the European Ceramic Society |
| Volume | 16 |
| Issue | 2 SPEC. ISS. |
| Pagination | 115 - 119 |
| Date Published | 1996 |
| ISSN | 09552219 (ISSN) |
| Abstract | In addition to its importance as a high-technology ceramic, mullite is also an intermediate phase in the formation of non-oxide ceramics (sialons) by carbothermal reduction of clay minerals. This reaction involved the formation of mullite under non-oxidizing atmospheres and in the presence of carbon. The effect of eight different reaction atmospheres on mullite formation from kaolinite in the presence and absence of carbon was studied by X-ray diffraction, 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. Generally, a greater amount of mullite is formed at 1200°C under vacuum and reducing atmospheres, which also produce mullites that are slightly more silica-rich (as deduced from X-ray lattice parameter measurements) but contain higher proportions of tetrahedral 27Al NMR resonance at ≈ 46 ppm, probably associated with Al* sites. Reaction systems containing either nitrogen or ammonia in the presence of carbon show NMR evidence of previously unreported early stage formation of Si-O-N bonds. Thermodynamic calculations are presented which suggest that the formation of SiO is an important factor in the complex interactions between the various solid and gaseous reactants. |
| URL | http://www.scopus.com/inward/record.url?eid=2-s2.0-0037806918&partnerID=40&md5=dc0d9a378b14095bd4ffb51d47315233 |
| DOI | 10.1016/0955-2219(95)00143-3 |
