Study of zirconium dioxide white pigment for space environment.

Abstract

The properties of zirconium dioxide as a stable white pigment (low a/e) for space application are investigated. A study of the optical absorption of single crystals indicates that a high degree of purity, except for hafnium, is essential for low a/e applications. A pigment preparation study and irradiation experiments with uv and 3-kev protons are described. The experimental ZrO 2 coatings initially have solar absorption a < 0.11 and thermal emittance e = 0.9. Over-all radiation stability (uv and proton) is shown to be binder dependent, with potassium silicate more stable than silicones. Potassium silicate coatings show A a = 0.06 after 2400 uv equivalent solar hours, and Aa = 0.01 after irradiation with 3-kev H + and H 2 + to a fluence of 10 16 particles/cm 2 .