Measurement of porosity in ceramic coatings by thermogravimetric volatilization of liquids
- Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering and Materials Science
- DuPont Chemical Co., Wilmington, DE (United States). Central Research and Development
A simple gravimetric method was developed to determine the open porosity in ceramic coatings. The coating`s pore space was filled with a liquid and the weight loss on volatilization of the liquid was measured in a thermogravimetric analyzer. This thermogravimetric volatilization of liquids (TVL) method was used to characterize the porosity in titania coatings, alumina/aluminum phosphate coatings, and free-standing films of alumina. Several liquids were used; ethylene glycol and 1,3-propanediol gave the best results due to their low volatilities at room temperature. The measured porosities of the ceramic coatings ranged from 30% to 80% and the pore sizes (as determined by SEM and mercury porosimetry) ranged from 0.1 to 15 {micro}m. The standard deviation of the TVL measurement was smaller for thicker coatings (e.g., {ge}20{micro}m). Porosities determined by TVL were within typically 5--10% of those determined by mercury intrusion porosimetry on identical samples. Characterization of a series of alumina/aluminum phosphate coatings showed a decrease in porosity consistent with expectations based on density and SEM observations. TVL is nondestructive, can be used for small volumes of sample, and when combined with SEM, provides a good means to characterize coating porosity and pore structure.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 422742
- Journal Information:
- Journal of the American Ceramic Society, Vol. 79, Issue 12; Other Information: PBD: Dec 1996
- Country of Publication:
- United States
- Language:
- English
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