General Electric Company

James F Fleischer

Thomas R Anthony

Robert H Ettinger

William F Banholzer

Robert C DeVries

Richard A Engler

David Winfield Woodruff

Harold P Bovenkerk

Jerome Johnson Tiemann

James William Bray

Steven Marc Gasworth

David E Slutz

Bradley E Williams

Laurence Bigio

Thomas R Fnthony

An improved method of producing a diamond tube by chemical vapor deposition and a hollow support mandrel used therein. The method comprises depositing a diamond film on an outer side of the hollow mandrel by the CVD process. The mandrel is then etched away by subjecting an inner side of the mandrel to the etching action. It was unexpectedly discovered that the etch time is drastically reduced by using the hollow mandrels.

Method of producing articles by chemical vapor deposition and the

Broadly, the present invention is directed to polycrystalline diamond of improved thermal conductivity. The novel polycrystalline diamond consists essentially of at least 99.5 wt-% isotopically-pure carbon-12 or carbon-13. The inventive polycrystalline diamond is formed from at least 99.5 wt-% isotopically-pure carbon-12 or carbon-13. Single-crystal isotopically-pure carbon-12 and carbon-13 diamond are known to possess improved thermal conductivity. Polycrystalline diamond, however, possesses lower thermal conductivity patterns deleteriously impacted by, for example, impurities, isotopic effects, and grain boundary scattering. In fact, grain boundary scattering would lead the skilled artisan to believe that the thermal conductivity of polycrystalline diamond would be substantially unaffected by the isotopic nature of the diamond itself. Unexpectedly, however, isotopic effects were discovered to predominate in impacting the thermal conductivity of polycrystalline diamond consisting essentially of isotopically-pure carbon-12 or carbon-13. This is true whether the isotopically-pure polycrystalline diamond is grown directly or whether individual isotopically-pure carbon-12 or carbon 13 diamond crystals are subjected to sintering for forming a polycrystalline structure, e.g. layer or compact, thereof.

Isotopically-pure carbon-12 or carbon-13 polycrystalline diamond

Chemical vapor deposition method for producing a fine grained smooth growth surfaced diamond film on a substrate employs a hydrogen/hydrocarbon gaseous atmosphere containing an amount of nitrogen effective to inhibit the growth of the diamond grains deposited on the substrate.

Smooth surface CVD diamond films and method for producing same

A process for shaping a thin, free-standing diamond film having a rough growth surface. The process includes the steps of: cutting the rough growth surface of said film with a laser to form a plurality of first ridges; translating said film in a direction parallel to said surface or rotating said film along an axis of rotation perpendicular to said surface; repeating said cutting to form a plurality of second ridges; and lapping said growth surface to reduce the height of said second ridges. The laser utilized may be a Nd:YAG laser and may be continuous or pulsed.

Preparation of thin free-standing diamond films

An apparatus for annealing diamond water jet mixing tubes comprises an enclosure, a vertical cylindrical heating tube in the enclosure, a heater for the heating tube and a rack in the heating tube to support the diamond mixing tube. Annealing relieves internal tensile stresses which can decrease the life of the mixing tube.

Apparatus for annealing diamond water jet mixing tubes

Broadly, the present invention is directed to improving a chemical vapor phase deposition (CVD) method for synthesis of diamond wherein a hydrocarbon/hydrogen gaseous mixture is subjected to a combustion flame in the presence of oxygen to at least partially decompose the gaseous mixture to form CVD diamond. The improvement in process comprises subjecting said combustion flame to one or more of dielectric heating, d.c. discharge, or a.c. discharge. Dielectric heating can be accomplished by subjecting the combustion flame to microwave (MW) frequency discharge or radiofrequency (RF) discharge. By superimposing dielectric heating or d.c./a.c. discharge plasma generation on combustion flame process, the carbon utilization rate of the combustion flame process should improve substantially. As noted above, given the low carbon utilization rate for combustion flame techniques already, small percentage improvements in the carbon utilization rates translate into substantial cost savings in generation of CVD diamond by such combustion flame technique.

Microwave RF, or AC/DC discharge assisted flame deposition of CVD diamond

A stress relieved CVD diamond is produced by annealing said CVD diamond at a temperature above about 1100 to about 2200 degrees Centigrade in a non-oxidizing atmosphere at a low pressure or vacuum and for a suitable short period of time which decreases with increasing annealing temperature so as to prevent graphitization of said diamond.

Method for enhancing the toughness of CVD diamond

Diamond workpieces comprised of polycrystalline CVD diamond having a grain size of less than 1 .mu.m are provided. These diamond workpieces are more resistant to wear and are more conducive to polishing than conventional diamond workpieces having large-grain diamonds. Three-dimensional workpieces such as water jet nozzles and water jet mixing tubes comprised of the small-grain diamonds provide particular advantage in that they can be easily finished to a final size and shape.

Fine grain diamond workpieces

Diamond is produced by chemical vapor deposition on a substrate by hot filament activation of a hydrogen-hydrocarbon gas mixture. An edge of the substrate faces the filament at a distance therefrom up to about 1 mm and preferably about 0.3-0.7 mm., and the substrate is moved relative to the filament to maintain this spacing as diamond forms thereon. Diamond formation proceeds at an improved rate, and in single crystal configuration under certain conditions.

Apparatus and method for chemical vapor deposition of diamond

Chemical vapor deposition of diamond with &lt;100&gt; orientation and (100) growth facets is performed at an increased growth rate and affords cubic diamond crystals when a gas mixture comprising hydrogen, a hydrocarbon such as methane and specific minor amounts of oxygen and an inert gas, preferably predominantly nitrogen, is employed.

Chemical vapor deposition of polycrystalline diamond with &lt;100&gt;

Diamond is produced by chemical vapor deposition on a substrate by hot filament activation of a hydrogen-hydrocarbon gas mixture. An edge of the substrate faces the filament at a distance; therefrom up to about 1 mm. and preferably about 0.3-0.7 mm., and the substrate is moved relative to the filament to maintain this spacing as diamond forms thereon. Diamond formation proceeds at an improved rate, and in single crystal configuration under certain conditions.

HF-CVD method for forming diamond

Single-crystal diamond consisting of isotopically pure carbon-12 or carbon-13 has been found to have a thermal conductivity higher than that of any substance previously known, typically at least 40% higher than that of naturally occurring IIA diamond. It may be prepared by a method comprising comminution of diamond of high isotopic purity, such as that obtained by low pressure chemical vapor deposition employing an isotopically pure hydrocarbon in combination with hydrogen, followed by conversion of the comminuted diamond to single-crystal diamond under high pressure conditions.

Single-crystal diamond of very high thermal conductivity

Graphite formation on a diamond surface during laser etching is inhibited or the graphite is removed by contact with a gaseous material such as elemental hydrogen, elemental oxygen, an inert gas or a source of hydroxyl radicals. Preferably, the article being etched is cooled and maintained in an inert atmosphere during etching.

Suppression of graphite formation during laser etching of diamond

The thickness of a layer of material deposited by chemical vapor deposition, especially a diamond layer, is monitored by providing at least one substrate on which the material is deposited, with at least one perforation of a predetermined size therein. The relationship between the thickness of the layer formed in said perforation and the thickness of the layer formed on the substrate surface is determined, so that the thickness of the surface layer can be determined from the thickness of the layer formed in the perforation.

Method for determining thickness of chemical vapor deposited layers

The bond strength between a diamond and the substrate onto which it is deposited by the chemical vaporization method is decreased to the point where the diamond can be removed from the substrate as a free standing monolithic sheet. The bond strength can be decreased by polishing the substrate, removing corners from the substrate, slow cooling of the substrate after deposition, an intermediate temperature delay in cooling or the application or formation of an intermediate layer between the diamond and the substrate. The free standing sheet of diamond can be used as a laser lens, metallized to form a mirror, or silver soldered to tungsten carbide to form a cutting tool.

Growing community of inventors

Scotia, NY, United States of America

James F Fleischer