Mechanical properties and solid particle erosion of MCD films synthesized using different carbon sources by BE-HFCVD

Abstract

Mechanical properties and solid particle erosion of chemical vapor deposition (CVD) diamond films are strongly influenced by the adopted carbon source in the deposition process. In the present study, methane, acetone, methanol and ethanol are respectively used as the carbon source to deposit micro-crystalline diamond (MCD) films on SiC substrates by the bias-enhanced hot filament CVD (BE-HFCVD) method. A standard air–sand erosion rig is employed to conduct erosion tests, using angular SiC sands of 320meshes as impact abrasives. The impact velocity ve and impact angle αe are fixed as 100m/s and 90°, respectively. The steady-state erosion rate εs, film life tr and a unit film life tru are defined to assess the erosion behaviors of as-deposited films, which have close relationships with the mechanical properties, as measured by the Rockwell hardness tester and the nanoindentation test. It's found that under the condition of the same film thickness, the methane-MCD film shows the lowest εs and the longest tr, owing to the highest surface hardness and the most favorable film-substrate adhesion which is equivalent to the highest fracture strength, but the opposite is true for the methanol-MCD film. Moreover, due to the relatively higher growth rate, the acetone- and ethanol-MCD films both perform even longer tru than the methane-one, indicating better “average” erosion behavior. Consequently, the optimal efficiency and economy can be achieved when adopting either the acetone or the ethanol to deposit MCD films of sufficient thickness on working surfaces of erosion resistant components suffering severe erosive wear, especially in the case of mass production.