The low-temperature chemical vapour deposition of tungsten carbide coatings utilising the pyrolysis of tungsten hexacarbonyl

A detailed study has been made of the atmospheric pressure chemical vapour deposition (CVD) of tungsten carbide coatings onto powder metallurgy (PM) BT42 grade high speed steel (HSS) indexable cutting tool inserts. The pyrolysis of tungsten hexacarbonyl (W(CO)6) deposition route was utilised in conjunction with a laboratory-scale hot-wall CVD reactor. After numerous coating runs, deposition conditions were established under which rudimentary tungsten carbide coatings could be deposited at 350°C. The characteristics of these coatings were determined using an established characterisation procedure. This involved the following techniques: X-ray diffraction, ball cratering, Auger electron spectroscopy (AES), optical microscopy, fractography/scanning electron microscopy (SEM), profilometry, scratch adhesion testing and micro-indentation hardness testing.