Raman studies of nanocomposite SiCN thin film by sputtering showed that with increase of substrate temperature from room temperature to 500 °C, a transition from mostly sp² graphitic phase to sp³ carbon took place, which was observed from the variation of I_D/I_G ratio and the peak shifts. This process resulted in the growth of C₃N₄ and Si₃N₄ crystallites in the amorphous matrix, which led to increase in hardness (H) and modulus (E) obtained through nanoindentation. However, at a higher temperature of 600 °C, again an increase of sp² C concentration in the film was observed but the H and E values showed a decrease due to increased growth of the graphitic carbon phase. The whole process got reflected in a modified four‐stage Ferrari–Robertson model of Raman spectroscopy. Copyright © 2010 John Wiley & Sons, Ltd.

Bismaleimide (BMI) resins are a new breed of thermosetting resins used mainly for high-temperature applications and have major usage in aerospace. Fourier transform infrared (FTIR) studies have shown signatures of imide, C–N–C stretching, maleimide, and N–H stretching. These BMI polymer coatings were deposited on aluminum (Al) and mild steel substrates by sprinkling powers followed by baking. Thermogravimetric analysis and differential scanning calorimetric studies showed the degradation temperature of these polymers around 370°C. Al coatings were deposited on BMI that is previously deposited on Al and mild steel to make a metal–BMI–metal trilayer. These trilayers can solve the problem charging of the aircraft bodies at high altitudes. Atomic force microscopy was done to determine the morphology of the surface. Roughness and thickness measurements of the BMI coatings were carried out by a surface profilometer. Vickers microhardness tests showed an increase in the hardness of the metal–BMI–metal trilayer. FTIR spectrum showed signatures of imides, C–N–C stretching, maleimide, and N–H stretching in BMI. Peak broadening indicates the release of the stress during thermal treatment of the coating. The coating is subject to variable Atmospheric Pressure Plasma Jet (APPJ) conditions, which improves the properties at high temperature. X-ray diffraction studies showed a hint of crystallinity on APPJ treatment.