AZW/LA-II is an inorganic white thermal control paint with extremely low solar absorptance, developed for use on spacecraft and satellite surfaces exposed to the deleterious effects of the space environment. The resulting nonspecular white coating provides superior thermal protection by allowing only 7-11% of the solar radiation impinging on the spacecraft external surface to be absorbed through to the interior systems while emitting 89-93% of the internal heat generated to the cold vacuum of space. AZW/LA-II incorporates a stabilized pigment system with a silicate binder and forms a ceramic coating that has been tested and proven itself stable in the harshness of the space environment. AZW/LA-II has been exposed by NASA to atomic oxygen (AO) fluence of 7.4 x 1020 atoms/cm2, and ultraviolet (UV) of approximately 832 equivalent solar hours with less than 4% deterioration in solar absorptance (α_s) and less than 1% change in thermal emittance (ε_t).
This spacecraft / satellite paint was flown on the Materials International Space Station Experiment (MISSE)and returned after 4 years in orbit with only a 0.03 overall degradation in solar absorptance from pre-flight measurements.
Though more expensive than AZ-93, AZW/LA-II has extremely low solar absorptance.
The table below lists the optical and application parameters of cured AZW/LA-II.
|Nominal Surface Resistivity||N/A|
|Thermal Emittance (ε_t)||0.91 ± 0.02|
|Solar Absorptance (α_s)||0.09 ± 0.02 at ≥ 10.0 mils thickness|
|Use Temperature Range||-180 C to 1400 C|
|Nominal Dry Thickness||7 to 13 mils (over 85% of coated area)|
|ASTM D3359A Adhesion Grade||Not less than 3A|
|Full Cure||7-14 days|
Note: terms reflectance, emittance and absorptance and terms reflectivity, emissivity and absorptivity are often used interchangeably.