| 摘要 |
60SD00551 SYMMETRIC CVD DIAMOND ARTICLES AND METHOD OF THEIR PREPARATION The present invention is directed to a method for the chemical vapor deposition (CVD) of a layer of diamond on a substrate held at elevated CVD diamond-forming temperature wherein a hydrocarbon gaseous mixtures is passed over a hot elongatefilament for at least partially decomposing said mixture to form said CVD diamond layer on said substrate. The present invention specifically is directed to forming a substantially uniformly thick CVD diamond layer on the substrate which is stationary. Such method comprises disposing said substrate stationarily at a distance, C, from a hot elongate filament. The substrate has a maximum radius, R, which is defined as the maximum distance from the center of the substrate to an outermost surface to be coated by the layer of CVD diamond. The substrate also is disposed parallel about its axis to the filament. The layer of CVD diamond becomes more uniform in thickness as theratio, R/C, decreases. An advantageous substrate is a wire which can be coated with a layer of CVD diamond for making a nozzle, wire drawing, die, or other annular article when the wire is separated from the resulting diamond annulus. For a wire substrate and two hot filaments, ratios of r/c of less than about 0.05 provide substantially uniform CVD diamond layers on the wire substrate. For a wire substrate and a single filament, ratios of r/c less than about 0/02 also provide substantially uniform CVD diamond layers.
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