FORMATION OF SELF-SUPPORTING HOLLOW DIAMOND HELIX AND DIAMOND SIEVE USING JET-FLOW HFCVD

This paper describes the methodology for the preparation of self- supp orting hollow diamond helix and diamond sieve in addition to diamond m icrotubes. The key idea is to deposit thick, compact and sufficiently strong coating on a suitable mandrel and then dissolve the latter so a s to form the required shape. For this purpose we have made use of 'je t-flow' HFCVD which allows diamond deposition over larger area on thre e dimensional substrates both inside as well as outside. X-ray diffrac tion, laser macro-Raman spectroscopy and scanning electron microscopy have been used to characterise shape, morphology and the phase purity of the material.