engleski

Optimization of corrosion resistance of high purity alumina ceramics in nitric acid

Developing ceramic materials with resistance to various corrosive media as well as certain mechanical characteristics is of considerable importance for enabling a wider application of these ceramics. Corrosion resistance depends on the purity and microstructure of the material along with the kind of the corrosive media and temperature. The corrosion behaviour of cold isostatically pressed high purity alumina ceramics (sintered in conventional - electrical kiln) in aqueous HNO3 solutions in a concentration range of 0.5 mol dm-3, 1.25 mol dm-3 and 2 mol dm-3 with different exposure times – up to 10 days – has been studied. The influence of temperature (25, 40 and 55 °C) on corrosion was also monitored. Corrosion resistance evaluation of Al2O3 ceramics was based on measurements of the mass concentrations of eluted Al3+, Ca 2+, Fe 3+, Mg 2+, Na + and Si 4+ ions by inductively coupled plasma atomic emission spectrometry (ICP-AES) and density by Archimedes method. Response surface methodology was used for optimization of parameters within experimental “sample-corrosive media” area. Exposure to corrosive media was conducted according to the Box-Behnken design. After regression functions were defined, conditions to achieve maximal corrosion resistance of sintered ceramics were determined by optimization within experimental area.

alumina ceramic, Box-Behnken design, corrosion resistance, optimization

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