Aluminium titanate

Mit Murexid reagieren ferner Eisen(II) und (III), Mangan(II) und Zinn(ll), ohne daB jedoch hiervon analytischer Gebrauch gemacht worden ware. Mit Blei- und Uranylion tritt nur sehr schwache Reaktion ein, wahrend Quecksilber, Aluminium, Titan und Chrom ohne EinfluB sind (163). 

For most particulate composites the mismatch between the particles and the matrix is more important than the anisotropy of either component (though alumina/aluminium titanate composites provide a notable exception and are described below). The main features of the stresses can therefore be understood in terms of a simple elastic model assuming thermoelastic isotropy and consisting of a spherical particle in a concentric spherical shell of matrix with dimensions chosen to give the appropriate volume fractions. The particles are predicted to be under a uniform hydrostatic stress, ap after cooling. If the particles have a larger thermal expansion coefficient than the matrix, this stress is tensile, and vice versa. For small particle volume fractions the stress... 

Plot of strength versus indentation load for alumina with various grain sizes and alumina/aluminium-titanate composite. The data points and solid line are from the composite. The other lines are for alumina with various grain sizes A, 2.5 pm, experimental B, 6 pm, interpolated C, 80 pm, experimental (reproduced from Bennison et al. [7] by kind permission of Taylor and Francis Ltd (http // www.tandf.co.uk/journals). 

Alumina/aluminium titanate and alumina-zirconia/ aluminium titanate systems... 

Low, I.M. (1998a) Processing of an in-situ layered and graded alumina-aluminium titanate composites. Mater. Res. Bull. 33, 1475-1482. 

Low, I.M. (1998b) Synthesis and properties of in-situ layered and graded aluminium titanate/alumina composites. J. Aust. Ceram. Soc. 34, 250-255. 

Manurung, P. (2001) Microstructural design and characterisation of alumina/aluminium titanate composites. Ph.D Thesis, Curtin University of Technology, Perth, Australia. 

Padture, N.P., Bennison, S.J. Chan, H.M. (1993) Flaw-tolerance and crack-resistance properties of alumina and aluminium titanate composites with tailored microstructures. J. Am. Ceram. Soc. 76, 2312-2320. 

Runyan, J.L. Bennison, S.J. (1991) Fabrication of flaw-tolerant aluminium-titanate-reinforced alumina. J. Eur. Ceram. Soc. 7, 93-99. 

Singh, M. Low, I.M. (2002a) Depth-profiling of phase composition and preferred orientation in a graded alumina/mullite/aluminium-titanate hybrid using x-ray and synchrotron radiation diffraction. Mater Res. Bull. 37, 1279-1291. 

A detailed investigation of soft mechanochemical synthesis of aluminium titanate was described in [60]. The data obtained in this study are the evidence of the formation of amorphous hydrated aluminium titanium compounds at the initial stages. These compounds are stable till 450-700°C at higher temperature they decompose to give aluminium and titanium oxides which form dispersed aluminium titanate at 1340°C. 

An interesting way of aluminium titanate preparing was proposed in [61,62]. A mixture of metallic aluminium with Ti02-H20 hydrogel was... 

Freudenberg B., Mocellin A. Aluminium titanate formation by solid state reaction of fine AI2O3 and T1O2 powders. J. Am. Ceram Soc. 1987 70 33-38. 

Kupin A.V., Prokofyev V.Yu., Ilyin A.P. Synthesis of aluminium titanate using stabilizing additives. Stekloi Keramika 1999 4 20-23. 

Aluminium titanate (tielite, Al2Ti05) has excellent thermal shock resistance but poor mechanical strength which can, however, be improved by reinforcing with whiskers of a related phase such as potassium hollandite (K2Al2Ti60i6). Such composites can be formed by thermal decomposition of sol-gel precursors, reaction sintering of the two phases or by thermal treatment of an appropriate glass-ceramic material. Al MS NMR has been used to study the co-formation of these two phases during thermal treatment, and indicates that hollandite crystallises as whiskers within the tielite matrix (Kohn and Jansen 1998). 

Figure 1. X-ray diffraction patterns of the functionally-graded aluminium titanate/zirconia-alumina composite at various depths. Labels AT=aluminium titanate, A=a-alumina, Z=zirconia (m monoclinic, t tetragonal). CuKa radiation was used.

Figure 1 shows the x-ray diffraction patterns of the FGM measured at several depths. The aluminium titanate (P-AliTiOs) in the sample is believed to form through the sintering reaction... 

Figure 2. Weight fraction of aluminium titanate (AT) and a-alumina according to depth in the functionally-graded aluminium titanate/zirconia-alumina composite. Error bars indicate 2x estimated standard deviations.

Table 1 Weight Fraction of Minor Phases and Mass Attenuation Coefficient of Aluminium Titanate/Zirconia-Alumina Composites as a Function of Sample...

A functionally-graded aluminium titanate/zirconia-alumina composite has been synthesised by a liquid infiltration. 

The presence of aluminium titanate appears to reduce the content of tetragonal zirconia possibly due to the formation of AT-induced residual stresses in the microstructure. 

Pratapa, S. and Low, I.M. (1996). Synthesis and Properties of Functionally-gradient Aluminium Titanate-Mullite-ZTA Composites . J. Mater. Sci. Lett. 15, 800-802. 

Ananthakumar S., Jayasankar M., Warrier K.G.K.. Microstructural, mechanical and thermal characterisation of sol-gel derived aluminium titanate-mullite ceramic composites. Acta Materialia, 2006,54 2965-2973... 

The improvement of the thermal shock behaviour of the composites may be attributed to a combination of a lower coefficient of thermal expansion and the higher thermal conductivity expected on the incorporation of metallic, SiC or aluminium titanate particles or of carbon fibres into the silicate matrices [108]. 

A. R. Boccaccini, and K. Pfeiffer, Preparation and Characterisation of a Glass Matrix Composite Containing Aluminium Titanate Particles with Improved Thermal Shock Resistance, Glass Sci. Technol. Glastech. Ber. 72, 352-357 (1999). 

Boccaccini AR, Pfeiffer K, Preparation and characterisation of a glass matrix composite containing aluminium titanate particles with improved shock resistance. Glass Sci Technol Glastech Ber, 72, 352-357, 1999. 

Torri, C. Lesci, I.G. Fabbri, D. Analytical study on the production of a hydroxylactone from catalytic pyrolysis of carbohydrates with nanopowder aluminium titanate. J. Anal. Appl. Pyrol. 2009, 84, 25-30. 

Fig. 8.64 Micrograph of a bridging site taken in situ in the SEM (secondary electrons) during crack propagation in an alumina/ aluminium titanate. P and Q denote frictions points during grain pull-out (courtesy of Nitin Padture) [21]. With kind permission of Dr. Jorge Lino...

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