Effect of chamber pressure and filament temperature on nucleation and growth of diamond on tungsten carbide cutting tool for machining aluminum

Hot Filament Chemical Vapour Deposition (HFCVD) is a promising method for producing low-pressure diamond coatings, offering simplicity, scalability, and cost-effectiveness. These studies examine the effect of chamber pressure, filament temperature, and pre-treatment on nucleation, morphology, and wear performance of CVD diamond coatings on tungsten carbide (WC) tool inserts. SEM (Scanning Electron Microscope) micrographs showed that crystal size and uniformity depend on deposition temperature and pressure. XRD (X-ray Diffraction) confirmed crystalline diamond deposition through a sharp (111) reflection diamond peak. µ-RS (Micro Raman Spectroscopy) confirmed a high-quality diamond phase with negligible graphitic contamination. Acid pre-treatment and diamond seeding were essential for successful nucleation and film integrity. Optimal deposition occurred at 2050°C filament temperature and 30 Torr chamber pressure, resulting in a homogeneous coating. CVD-diamond coated tools exhibited highest VHN (Vickers microhardness number) and least abrasive wear when machining aluminium versus uncoated tools under identical machining conditions (parameters such as feed rate, cutting speed, and depth of cut were taken the same for both the tools). These findings demonstrate HFCVD diamond coatings' effectiveness for improving cutting tool durability, particularly in non-ferrous metal machining.