In order to investigate the possibility of the use of 1:1 type clay minerals as raw materials for nitride production, kaolinite and antigorite were converted into nitrides by carbothermal reduction. Kaolinite or antigorite was mixed with carbon in two separate experiments. The resulting mixture was heated in N2. Kaolinite was converted into β'-sialon and AIN. Kaolinite was initially transformed into cristobalite and mullite, which were then reduced. In addition to the nitrides, SiC and α-Al2O3 also formed as the reactions proceeded. Essentially, both the SiO2 and Al2O3 components were converted into nitrides and oxynitrides by carbothermal reduction. From the antigorite-carbon mixture, α- and β-Si3N4 were obtained. Forsterite initially crystallized and was reduced. Additionally, MgSiN2 and MgO formed during the conversion. α-Fe and FexSi were also detected. MgSiN2 seemed to act as an intermediate for Si3N4 formation. Therefore, all the Mg-containing phases can not be present as nitrides finally; magnesium was lost as the reactions proceeded.
ASJC Scopus subject areas
- Geochemistry and Petrology