RM-400 Thermal Control, Electrically Conductive Paint / Coating

RM-400 is an organic electrically conductive thermal control white to off white paint developed for use on spacecraft and other equipment which contain sensitive electronic circuitry. Due to the ceramic nature of conventional thermal control coatings, charge buildup and subsequent electrostatic discharges from the surface of the coating to conductive components (skin panels, circuitry, exposed metal, etc.) can cause damage to sensitive electronic components. Epoxy-based RM-400 provides electrical conductivity such that any accumulated charges can be safely drained off and therefore avoid an electrostatic discharge that could cause catastrophic damage. The thermal protection provided by RM-400 is of secondary importance to the conductivity. Typically, RM-400 is ony a good choice for short-duration space flights as it will not maintain its properties for extended flights.

Its main advantage over AZ-2000-IECW and AZ-2100-IECW lies in its flexibility with respect to tailoring its conductivity properties.

The table below lists the electrical, optical and application parameters of cured RM-400.

Nominal Surface Resistivity Tailorable up to 105 Ω/sq
Thermal Emittance (ε_t) ~0.88
Solar Absorptance (α_s) ~0.45 at ≥ 5.0 mils thickness
Use Temperature Range -180 C to 260 C
Appearance/Color White to off-white
Nominal Dry Thickness 4.0 ± 1.5 mils (over 85% of coated area)
ASTM D3359A Adhesion Grade Not less than 3A
Full Cure 48 to 72 hours
Coating coverage estimates can be found here.
The SDS can be found here.

View a typical spectral reflectance curve for RM-400 (pdf 40KB). Measurements were taken with AZ Technology’s Laboratory Portable SpectroReflectometer LPSR-300.

Note: terms reflectance, emittance and absorptance and terms reflectivity, emissivity and absorptivity are often used interchangeably.