MPCVD diamond tool cutting-edge coverage: dependence on the side wedge angle

• Published in: Diamond and related materials Vol. 10; no. 3; pp. 803 - 808
• Main Authors: Fernandes, A.J.S., Silva, V.A., Carrapichano, J.M., Dias, G.R., Silva, R.F., Costa, F.M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-03-2001; Elsevier
• Subjects: Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Chemical vapour deposition (CVD); Cross-disciplinary physics: materials science; rheology; Diamond-coated tools; Exact sciences and technology; Growth; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Temperatures; Temperatures; Chemical vapour deposition (CVD); Growth; Diamond-coated tools; Grain size; Temperature distribution; Cutting tools; Films; Synthetic mineral; Digital simulation; Diamonds; Crystal growth from vapors; Ceramics; Experimental study; Coatings; CVD; Finite element method; Edge effect; Nonmetals; PECVD; Microstructure; Microwave discharge
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/S0925-9635(00)00540-9

Microwave plasma CVD usually produces uniform diamond coatings and high-quality diamond films. However, abnormal deposits appear near the sample edges — the so-called ‘edge effect’. Wedge-shaped silicon nitride inserts with 30°-, 60°-, 75°- and 90°-edge angles were vertically and horizontally exposed to MPCVD diamond coating to systematically study this effect. Finite element method (FEM) analysis was used to simulate the temperature distribution on such geometries. Diamond morphology and quality were assessed by SEM and micro-Raman techniques. The edge effect, a consequence of plasma concentration and thermal phenomena in this experimental set-up (activation by electromagnetic gas discharge), is more accentuated on samples that are vertically wedge-oriented towards the plasma. A grain-size gradient is established along the exposed surface, steeply increasing at the hot edge. An extreme effect occurs in the sharpest wedge samples, avoiding diamond growth at the edge.