Influence of deposition temperature on microstructure formation of Ti-Al-C-N ceramic coatings prepared via pulsed-DC PACVD

Ti-Al-C-N coatings were deposited on AISI H13 hot work tool steel substrates using PACVD method at deposition temperatures of 350, 425 and 500 degrees C. The results showed that synthesized nanostructured coatings consist of Ti-rich fcc-(Ti,Al)(C,N) and w-AlN nano-grains as well as an amorphous carbon nitride (a-CNx) phase. Increasing of the deposition temperature from 350 degrees C to 500 degrees C enhanced the intensity ratio of Disordered peak (ID) to Graphite peak (IG) from 0.94 to 1.13, respectively which is attributed to the increased graphitization of a-CNx phase. Rising the deposition temperature from 350 degrees C to 425 degrees C decreased the crystallite size from 11 to 9 nm, while further temperature increase to 500 degrees C generated larger crystallites of 13 nm. Layers of 2.33, 1.63 and 2.02 um thickness were developed at different temperatures of 350, 425 and 500 degrees C, respectively. This behavior caused by increasing the temperature was originated from two competitive factors; the reduction of growth rate induced by more intense ion sputtering and the increase of growth rate induced by grain growth. Another result obtained by increasing the temperature from 350 degrees C to 500 degrees C was noticed as a 40% higher surface roughness due to more intense ion sputtering effect and grain growth. Finally, the highest micro-hardness value was measured as 4240 +/- 53 HV0.01 for the coating deposited at 425 degrees C associated with the smallest crystallite size.

Automated summary

The Ti-Al-C-N coatings deposited on AISI H13 hot work tool steel substrates using PACVD method at different deposition temperatures exhibited varying microstructures and properties. Increasing the deposition temperature resulted in larger crystallite size, higher surface roughness, and increased micro-hardness values.