Amorphous aluminosilicate glass

In principle these compounds offer access to materials with AliCh-SiCL and Al203 2Si02 stoichiometries. The latter stoichiometry is equivalent to the Al[OSi(OBu-t)3 (OBu-t)] precursor. The major drawbacks with these materials are their air and moisture sensitivity, and the cost of the starting materials. Although the idealized stoichiometries of the above ceramics products are not those of crystalline aluminosilicates, amorphous aluminosilicate glasses are often important in optical applications or in scratch-resistant coatings. Furthermore, they may offer potential for CVD-type applications. There still remains considerable need for simple precursors to crystalline aluminosilicates, especially for structural applications. Dense, phase pure crystalline ceramic materials are desired for optimal mechanical properties, e.g. ceramic fibers for composite manufacture. 

Above 1100 °C the rearrangement of the defect spinel into amorphous silica and mullite accelerates with the mullite becoming progressively richer in aluminium up to 1500 C. On cooling the mullite crystallises into needles, which are embedded in an amorphous aluminosilicate glass. It is a very hard, abrasive mineral, which is virtually inert to all chemicals and environments. 

Y. Cao and A.N. Cormack. A structural model for interpretation of an anomaly in alkali aluminosilicate glasses at Al/alkali = 0.2-0.4. In H. Jain and D. Gupta, editors, Diffusion in Amorphous Materials, pages 137-151, Warrendale, PA, 1994. The Minerals, Metals and Materials Society. 

Figure 8.11. Young s modulus at 293 K (exceptfor amorphous ice T=77K is considered) and glass transition temperature of glasses. TAS and 2S2G standfor TesAs es and Gafje2ifb 11 65 respectively. E and R glasses are high strength industrial aluminosilicate glasses...

Silicon is observed in waters following the decomposition of aluminosilicates under the effects of CO2 and HjO. The solubility of amorphous and crystalline Si02 (quartz) is also quite significant. Artificial sources of silicon in waters are some industrial wastewaters of inorganic-based industry (e.g. in glass and ceramic production). 

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