Aluminum compounds thermodynamic properties

Another valuable source is the thermochemical property database assembled by Burcat and Ruscic [29], which is available online at ftp // ftp.technion.ac.il/pub/supported/aetdd/thermodynamics/. This collection is regularly updated by Prof. Burcat. It contains data for 1500 species, presented in the form of polynomial coefficients that can be used to compute the enthalpy, entropy, and heat capacity as a function of temperature. While Burcat s tables include a number of aluminum-oxygen compounds, they do not happen to include the aluminum-chlorine species that we have been using as an example. Of course, there are many other handbooks and compilations of thermodynamic properties. However, the vast majority of these focus on organic compounds and/or condensed phase species. Standard handbooks, such as the CRC Handbook of Chemistry and Physics, rarely have any information not included in the sources cited above. 

Sulfur compounds, whether organic or inorganic in nature, cause sulfidation in susceptible materials. The sulfide film, which forms on the surface of much con-stmction materials at low temperatures, becomes friable and melts at higher temperatures. The presence of molten sulfides (especially nickel sulfide) on a metal surface promotes the rapid conversion to metal sulfides at temperatures where these sulfides are thermodynamically stable. High-alloy materials such as 25% Cr, 20% Ni alloys are widely used, but these represent a compromise between sulfidation resistance and mechanical properties. Aluminum and similar diffusion coatings can be of use. 

Whenever silicon nitride is synthesized in the presence of aluminum-containing compounds (frequently used as a flux material in process of growing whiskers), there is a high probability of the formation of /3 -SiA10Ns. Up to two-thirds of the silicon in /3-Si3N4 can be substituted by Al without a change of structure. The /3 -SiAl()N has mechanical and physical properties similar to y3-Si3N4. It is, however, thermodynamically more stable than silicon nitride. 

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