- Conference date: 1–3 November 2012
- Location: Mumbai, India
Graphite is a widely used structural material for high temperature and high vacuum applications in furnaces handling corrosive materials or plasmas. The porosity, density, dimensions, impurities along with the history of graphitization, handling and storage of graphite dictate the outgassing characteristics. Graphite plates of density 1.78 g/cc were outgassed up to 1200 °C in vacuum of the order of 5×10−5 mbar in an in-house facility. A sample of the degassed graphite was taken for Thermo-Gravimetric Analysis (TGA). The TGA of the outgassed sample shows continuous weight loss in the temperature range of 200 °C to 1200 °C, indicating a much higher temperature is required for complete removal of gases. However, it may be noted that total outgassing is a function of the dimensions of the sample. The small coupon used in the TGA studies may not exactly replicate the large graphite blocks that outgases from the surface as well as from the bulk. The behaviour of graphite plates used in the liquid metal handling furnace where the graphite was finally used further confirmed this observation. The outgassing shown by the degassed graphite can be attributed to the diffusion of the absorbed gases from the bulk as well as desorption of the chemisorbed species which requires higher activation energies and higher temperature.
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