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

Abstract

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 °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 °C to 500 °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 °C to 425 °C decreased the crystallite size from 11 to 9 nm, while further temperature increase to 500 °C generated larger crystallites of 13 nm. Layers of 2.33, 1.63 and 2.02 μm thickness were developed at different temperatures of 350, 425 and 500 °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 °C to 500 °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 °C associated with the smallest crystallite size.