Mitigating residual stress of high temperature CVD diamond films on vanadium carbide coated steel

Abstract

In this work, a process condition was created to deposit a thin film of diamond on AISI O1 steel in a hot filament chemical vapor deposition (CVD) reactor. The main drawbacks to overcome are the diamond film high residual stresses caused by the difference between the coefficient of thermal expansion (CTE) of steel (∼12 × 10−6 K−1) and diamond (0.8 × 10−6 K−1). Our group proposed a diffusion vanadium carbide (VC) interlayer as a potential solution to mitigate carbon dissolution in the substrate and graphite formation instead of diamond; however, the intermediate CTE of VC still provides high thermal stress and delamination of the film. A solution was proposed by performing the diamond CVD on the AISI O1 steel substrate above the steel austenitizing temperature, under the prospect that thermal stress will be minimized during cooling, since the return of steel from faced-centered cubic to body-centered cubic crystalline structures will cause substrate expansion. The lower residual stress was accomplished by the diamond growth temperature of 840 °C with all the steel substrate above the austenitizing critical temperature. The residual stress mitigation was 3.9 GPa, merging VC interlayer and high growth temperature, where numerical simulation exposed the same stress created by the growth temperature at 545 °C.

Structural analyses of carbon films deposited at different total mass rates in a hot-filament CVD system

“…Studies on carbon films are being published routinely in various journals, and a few recently published studies discuss some exciting insights. 13–28 When deposited at different thicknesses, the nanometer-thick carbon films do not have the same characteristics. 29…”

“…Studies on carbon films are being published routinely in various journals, and a few recently published studies discuss some exciting insights. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] When deposited at different thicknesses, the nanometer-thick carbon films do not have the same characteristics. 29 Carbon films rich in diamond were deposited on uniquely treated substrates.…”