Energy conservation is one of the most important aspects of efficient energy generation and use. Improving thermal insulation is a practical approach to energy conservation. On the other hand, there are also applications where thermal insulation is needed to protect the underlying substrate from degradation. This, particularly in aircraft, is a commonly faced issue. High temperatures caused by hot plume impingement from engine ducts are detrimental to the aircraft’s structure, whether aluminium alloy or carbon composite, irrespective of the material.

CSIR-National Aerospace Laboratories (CSIR?NAL), Bengaluru developed a paint coating technology to provide thermal insulation for aircraft surfaces. The technology aims to mitigate the heating issue noticed in CSIR?NAL designed and developed SARAS PT1N aircraft, wherein engine exhaust plume, at a mass flow rate of 1.1 kg/s per stub of temperature ~150°C, was impinging the rear fuselage and adjoining areas.

The coating provides a temperature drop of ~25ºC when exposed to temperatures of 150ºC compared to an uncoated surface. The coating has excellent adhesion and is suitable for metals and composites. The method adopted is a simple room temperature process with low coating density (~0.85 g cm?3) and therefore less weight penalty. It is easily scalable and feasible on complex structures and supports onsite repairs. The paint coating is compatible with epoxy and polyurethane paint on aircraft surfaces.

The paint coating has qualified several stringent environmental and mechanical tests such as artificial weathering, sand, dust, driving rain, flammability, CATH, salt fog, contamination by fluids (aviation fuel, engine oil, hydraulic oil), pull-off adhesion, vibration, thermal shock, thermal stability up to 200°C, thermal cycles, etc. as per relevant ASTM, Military and RTCA standards. The paint has been accorded with Pre-Production Clearance by RCMA(F&F), CEMILAC, vide letter ref: RCMA(F&F)/323/2023/pc-10 dated 17/08/2023.

CSIR?NAL is now interacting with industries for possible technology transfer and continuing the activity for temperatures >300ºC. The development of a novel indigenous paint certified by CEMILAC will augment the ongoing SARAS MK II programme of CSIR-NAL that in turn, upholds the national slogan of Make in India.