STRUCTURE DEPENDENCE OF W DIFFUSION IN TiN-TiCN PROTECTIVE COATINGS FOR SPACE APPLICATION

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P. Tabakova¹, S. Atanasova¹, A. Petrova¹, I. Zahariev², K. Grigorov¹

¹Space Research and Technology Institute, Bulgarian Academy of Sciences

²Institute of Physical Chemistry “Rostislaw Kaischew”,

BULGARIAN ACADEMY OF SCIENCES

Keywords: Protective TiN-TiCN coatings, WC, diffusion coefficient

National Space Forum 2025 NAFSKI-VI, Sofia 27-29 October 2025

Titanium carbonitrides (TiN, TiCN) are wear resistant hard coatings used at spacecraft and aerospace industry to protect surfaces of strategical meaning at extreme conditions, such as temperatures with vast gradients, intensive radiation, vacuum and in some rare case – high-temperature plasma. They combine high hardness at low friction of the TiC-phases and high toughness, absorb energy and deform plastically of the TiN phases.

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Ti-based coatings deposited on Tungsten carbide (with Co as a binder) by CAD (Cathodic Arc) grows dense structures which inhibit the subsequent elements diffusion. The latter lead compromises its mechanical properties. To trace the elemental depth distribution, Glow-Discharge-Optical-Spectroscopy (GDOES) was used in order to quantified the W diffusion in both, TiN and TiCN coatings under specific temperatures.

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Experimental data

Depth elemental composition measured on sample with different roughness using GDOES

TiN/WC

TiCN/WC

National Space Forum 2025 NAFSKI-VI, Sofia 27-29 October 2025

Experimental dependence of W diffusion for both coatings TiN and TiCN

TiN

TiCN

Low friction coatings

National Space Forum 2025 NAFSKI-VI, Sofia 27-29 October 2025

Conclusion

The TiN-TiCN system coatings as a diffusion barrier are very successful, because of higher activation energy of the process and low diffusion pre-exponential coefficient. Therefore it prevents W diffusion in the higher temperature region. Due to its dense crystalline structure and good hardness with low FC it maintain lower processing temperatures.

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