DESIGN OF INORGANIC WATER REPELLENT COATINGS FOR THERMAL PROTECTION INSULATION ON AN AEROSPACE VEHICLE

摘要: The objective of this research was two-fold: first, to identify and test inorganic water-repellent materials that would be hydrophobic even after thermal cycling temperatures above 600 C and, second, develop a model link hydrophobicity material the chemical properties its constituent atoms. Four different were selected for detailed experimental study, namely, boron nitride, talc, molybdenite, pyrophyllite, all which have layered structure made up ionic/covalent bonds within layers but with van der Waals between layers. tested could considered nonporous surface none observed contact angles exceeded necessary 90 degrees required water repellency porous materials. Boron nitride talc retain their water-repellency when heated in air did not exceed 800 C, molybdenite found C. For these three materials, oxidation decomposition identified main cause breakdown repeated cycling. Pyrophyllite shows maximum promise as potential material, which, treated initially at 900 retained shape remained two cycles where retreatment temperature is A developed predicting might exhibit by linking properties, ions compound belong soft acid-base category fractional ionic character less than about 20 percent.