M. Verdenelli et al /Journal of the European Ceramic Society 23(2003)1207-1213 1209 alkoxides was recently reviewed by Turova and co- workers. 3 Acetylacetone was used as chelating agent to stabilize the aluminium precursor and to prevent pre- cipitation. The best results were obtained with a molar 00°C ratio AI(OR)3: acacH=1: I A cationic surfactant(CTAB) was used to create the mesoporosity in the inorganic network Self assembly of the surfactant due to electrostatic interactions with the 1300°C inorganic precursors allow the formation of rod-like micelles 20-23 Association of the cationic head of the surfactant with anionic aluminosilicates lead to lamellar 1200°C phase which tend to form hexagonal mesophase as polymerisation of the silicates proceeds. Further elim l100°C ination of the surfactant during thermal annealing gen- erates the porosity in the inorganic network. 3. 2. Characterization of the powders 2 theta(deg) X-ray diffraction (XRD), thermal (TGA, SDTA DSC)and thermo-mechanical (TMA) analysis were the powders issued from the complete hydrolysis of the solution. The results of the X-ray dif- fraction experiments are presented in the Fig. 2. The 1400°C sample 1(Fig. 2a) started to crystallise between 1000 and 1100C, in the pure mullite Al6Si2O13 phase Crys- tallisation for the sample 2(Fig. 2b) started higher, between 1200 and 1300C. The main phase was the 300°C A-Al2O3(corundum)and the secondary phase appeared to be the mullite. TGa and dSc were performed to investigate the behavior during the thermal treatments 1200°C TGA and DSC analysis performed on samples 1 and 2 showed approximately the same behavior with the pre- 60 60 70 cursors complete decomposition in the same tempera 2 theta(deg) ture range(Fig 3a, b) The TGA(Fig. 3a) showed complete elimination of the organics between 100 and 600 oC with about 70- Fig. 2. X-ray difiraction patterns on the powders issued from com- plete hydrolysis of the precursors for samples 1(a) and 2(b)and 80%loss of mass. The DSC results(Fig. 3b)showed the heated at various temperatures (O: mullite, * al-Al2O3 endothermic melting point of the CtAB at 100C fol lowed by the melting point of the aluminium acety % exo 50100150200250300350400450C Fig 3. TGA/SDTA (a)and DSC(b) for samples I and 2alkoxides was recently reviewed by Turova and co￾workers.13 Acetylacetone was used as chelating agent to stabilize the aluminium precursor and to prevent pre￾cipitation. The best results were obtained with a molar ratio Al(OR)3:acacH=1:1. A cationic surfactant (CTAB) was used to create the mesoporosity in the inorganic network. Self assembly of the surfactant due to electrostatic interactions with the inorganic precursors allow the formation of rod-like micelles.2023 Association of the cationic head of the surfactant with anionic aluminosilicates lead to lamellar phase which tend to form hexagonal mesophase as polymerisation of the silicates proceeds. Further elim￾ination of the surfactant during thermal annealing gen￾erates the porosity in the inorganic network. 3.2. Characterization of the powders X-ray diffraction (XRD),thermal (TGA,SDTA, DSC) and thermo-mechanical (TMA) analysis were performed on the powders issued from the complete hydrolysis of the solution. The results of the X-ray dif￾fraction experiments are presented in the Fig. 2. The sample 1 (Fig. 2a) started to crystallise between 1000 and 1100
C,in the pure mullite Al6Si2O13 phase. Crys￾tallisation for the sample 2 (Fig. 2b) started higher, between 1200 and 1300
C. The main phase was the a-Al2O3 (corundum) and the secondary phase appeared to be the mullite. TGA and DSC were performed to investigate the behavior during the thermal treatments. TGA and DSC analysis performed on samples 1 and 2 showed approximately the same behavior with the pre￾cursors complete decomposition in the same tempera￾ture range (Fig. 3a,b). The TGA (Fig. 3a) showed complete elimination of the organics between 100 and 600
C with about 70– 80% loss of mass. The DSC results (Fig. 3b) showed the endothermic melting point of the CTAB at 100
C fol￾lowed by the melting point of the aluminium acetyl￾Fig. 2. X-ray diffraction patterns on the powders issued from com￾plete hydrolysis of the precursors for samples 1 (a) and 2 (b) and heated at various temperatures (O:mullite, :a-Al2O3). Fig. 3. TGA/SDTA (a) and DSC (b) for samples 1 and 2. M. Verdenelli et al. / Journal of the European Ceramic Society 23 (2003) 1207–1213 1209