Fabrication and application of chemical vapor deposition diamond-coated drawing dies

A diamond coating has been fabricated by straight hot filament chemical vapor deposition (CVD) passing through the interior hole of the drawing die using a mixture of hydrogen and acetone as source gases. The substrates are drawing dies made by cemented carbides with large apertures (φ>2 mm), and are pre-treated by various methods including leaching Co by acid solution, scratching the substrate by diamond powder and decarburizing the WC substrate by microwave plasma. The homogeneity of coatings is estimated by scanning electron microscopy and Raman spectroscopy. The preliminary applied tests show that the adhesion strength of diamond coatings can meet the need of the practical drawing wires. As compared with the cemented carbide drawing die, the working lifetime of the diamond-coated drawing die can be increased by a factor of five to 10.