Nano- and microcrystalline diamond deposition on pretreated WC-Co substrates: structural properties and adhesion

Author(s)

Fraga, M. A. ^[1] ; Contin, A. ^[1] ; Rodriguez, L. A. A. ^[2] ; Vieira, J. ^[1] ; Campos, R. A. ^[3] ; Corat, E. J. ^[1] ; Trava Airoldi, V. J. ^[1]

Affiliation

^[1] Natl Inst Space Res, Sao Jose Dos Campos - Brazil

^[2] Univ Fed Sao Paulo, Sao Jose Dos Campos - Brazil

^[3] Fed Inst Sao Paulo, Jacarei - Brazil

• Document type: Journal article
• Source: MATERIALS RESEARCH EXPRESS; v. 3, n. 2 FEB 2016.
• Web of Science Citations: 6

Abstract

Many developments have been made to improve the quality and adherence of CVD diamond films onto WC-Co hard metal tools by the removing the cobalt from the substrate surface through substrate pretreatments. Here we compare the efficiency of three chemical pretreatments of WC-Co substrates for this purpose. First, the work was focused on a detailed study of the composition and structure of as-polished and pretreated substrate surfaces to characterize the effects of the substrate preparation. Considering this objective, a set of WC-9% Co substrates, before and after pretreatment, was analyzed by FEG-SEM, EDS and x-ray diffraction (XRD). The second stage of the work was devoted to the evaluation of the influence of seeding process, using 4 nm diamond nanoparticles, on the morphology and roughness of the pretreated substrates. The last and most important stage was to deposit diamond coatings with different crystallite sizes (nano and micro) by hot-filament CVD to understand fully the mechanism of growth and adhesion of CVD diamond films on pretreated WC-Co substrates. The transition from nano to microcrystalline diamond was achieved by controlling the CH4/H-2 gas ratio. The nano and microcrystalline samples were grown under same time at different substrate temperatures 600 degrees C and 800 degrees C, respectively. The different substrate temperatures allowed the analysis of the cobalt diffusion from the bulk to the substrate surface during CVD film growth. Furthermore, it was possible to evaluate how the coating adhesion is affected by the diffusion. The diamond coatings were characterized by Raman spectroscopy, XRD, EDS, FEG-SEM, atomic force microscope and 1500 N Rockwell indentation to evaluate the adhesion. (AU)

• FAPESP's process: 13/25939-8 - Study of interfaces by laser cladding for CVD diamond deposition
• Grantee: Andre Contin
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 14/18139-8 - Growth and doping studies of mono-crystalline CVD-diamond, dye-colored via discharge of high-power mW 2.45 GHz
• Grantee: Mariana Amorim Fraga
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 12/15857-1 - Scientific studies and innovation application on CVD diamond, DLC and carbon nanostructures obtained by chemical vapor deposition technique
• Grantee: Vladimir Jesus Trava-Airoldi
• Support Opportunities: Research Projects - Thematic Grants