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

A diamond coating has been fabricated by straight hot filament chemical vap or deposition (CVD) passing through the interior hole of the drawing die us ing a mixture of hydrogen and acetone as source gases. The substrates are d rawing dies made by cemented carbides with large apertures (phi > .2 mm), a nd are pre-treated by various methods including leaching Co by acid solutio n, scratching the substrate by diamond powder and decarburizing the WC subs trate by microwave plasma. The homogeneity of coatings is estimated by scan ning electron microscopy and Raman spectroscopy. The preliminary applied te sts show that the adhesion strength of diamond coatings can meet the need o f the practical drawing wires. As compared with the cemented carbide drawin g die, the working lifetime of the diamond-coated drawing die can be increa sed by a factor of five to 10. (C) 2001 Elsevier Science B.V. All rights re served.