Effect of Pressure and Temperature on Microstructure of Self-Assembled Gradient AlxTi1-xN Coatings

journal article in Web of Science

English

The correlation between structural properties of Al-rich self-assembled nano-lamellar AlxTi1-xN coatings and process parameters used during their chemical vapor deposition (CVD) remains unexplored. For this article, two gradient AlxTi1-xN coatings were prepared by a stepwise increase in temperature and pressure in the ranges of 750-860 degrees C and 1.56 to 4.5 kPa during the depositions at a constant composition of the process gas mixture. The cross-sectional properties of the coatings were analyzed using X-ray nanodiffraction (CSnanoXRD) and electron microscopy. Experimental results indicate that the variation of the process parameters results in changes in microstructure, grain morphology, elastic strain, nanolamellae's chemistry and bi-layer period. At temperatures of similar to 750-800 degrees C and pressures of 2.5-4.5 kPa, preferably cubic nanolamellar grains are formed, whose microstructure correlates with the build-up of tensile stresses, which become relaxed in coating regions filled with nanocrystalline grains. CSnanoXRD superlattice satellite reflections indicate the period of the cubic Al(Ti)N-Ti(Al)N bilayers, which changes from 6.7 to 9 nm due to the temperature increase from 750 to similar to 810 degrees C, while it remains nearly unaffected by the pressure variation. In summary, our study documents that CVD process parameters can be used to tune microstructural properties of self-assembled AlxTi1-xN nanolamellae as well as the coatings' grain morphology.

protective coating; TiAlN; self-assembly; LP-CVD; TEM; X-ray nanodiffraction

ZÁLEŠÁK, J.; TODT, J.; MICHALIČKA, J.; SARTORY, B.; MATKO, I.; LESSIAK, M.; TRAXLER, M.; WEISSENBACHER, R.; PITON, R.; GAMMER, C.; KECKES, J.

1. 4. 2021

MDPI

BASEL

2079-6412

Coatings, MDPI

11

4

Swiss Confederation

416-1

416-15

15

https://www.mdpi.com/2079-6412/11/4/416