Abstract: A method of forming a pyrolytic boron nitride (PBN) article and an article having layers of PBN separated by layers of PBN having a dopant of sufficient concentration to induce peeling, the steps of introducing vapors of ammonia and a gaseous boron halide in a suitable ratio into a heated furnace reactor to cause boron nitride to be deposited in layers on a substrate, with at least one gaseous dopant injected into furnace at controlled periodic interval(s) such that at least two selected layers of boron nitride are doped with said gaseous dopant(s) at a minimum average concentration of 2 atomic wt % at a depth ranging from 1000 to 2000 angstroms in each selected layer, and with the selected layers spaced apart about 0.1 micron to 100 microns apart.

Abstract: An article with an chemical vapor deposition (CVD) aluminum nitride coating is disclosed. The article is a heating element, wafer carrier, or electrostatic chuck. The article has a substrate made of a nitride of aluminum or boron, and further has one or more graphite elements for resistance heating or electromagnetic chucking or both. A pyrolytic boron nitride layer may be provided between the substrate and the CVD aluminum nitride coating, and may either encompass or exclude the graphite element or elements.

Abstract: A flash evaporator vaporization vessel for flash evaporating metal under conditions of repeated thermal cycling having a graphite body and an outer layer of pyrolytic boron nitride having a density above 2.15 gm/cc and preferably between 2.19 gm/cc and 2.2 gm/cc.

Abstract: A low viscosity filler boron nitride agglomerate particles having a generally spherical shape bound together by an organic binder and to a process for producing a BN powder composition of spherically shaped boron nitride agglomerated particles having a treated surface layer which controls its viscosity.

Abstract: The resistant heated flash evaporator of the present invention is designed for flash evaporating a metal charge in a confined area and is substantially horse shoe in geometrical configuration having opposite ends and an upper section with the upper section having a recessed cavity adapted to receive the metal charge and having two leg sections extending downwardly from the opposite ends of the vessel. The cross sectional dimension of each leg section nearest the recessed cavity is substantially smaller in size than the cross sectional dimension of each leg section as it recedes therefrom so as to form a large open area below the recessed cavity.

Abstract: In accordance with the present invention at least two different grades of HOPG material with different d-spacings are combined to form a composite HOPG monochromator with increased spacing spread (&Dgr;d/d) defined by the combination of the two HOPG materials with each HOPG material oriented relative to one another so that their layer planes are parallel. The increased &Dgr;d/d should yield higher neutron beam intensities in certain types of backscattering instruments.

Abstract: A pyrolytic boron nitride radiation heating unit including a dielectric base of boron nitride, a heating element of pyrolytic graphite superimposed on the dielectric base, a first outer coating surrounding said heating element composed of pyrolytic boron nitride and a second outer coating surrounding said first outer coating and having an emmissivity above at least about 0.9 at a wave length of 1.55 microns. The second outer coating is preferably selected from the group consisting of silicon carbide and boron carbide.

Abstract: A thin flexible heat transfer device for transferring heat from a heat source to a heat sink which may be located a substantial distance apart from each other. The heat transfer device includes a thin sheet of a non-structural, high thermal conductivity core material consisting of pyrolytic graphite or highly ordered pyrolytic graphite of a thickness between 2 microns and 2 mm and a pair of flexible face sheets each of a metallic composition having a maximum thickness of less than 25 mils disposed upon opposing surfaces of said core material to form a sandwich construction in cross section with the sheet of core material having a width smaller than the width of said face sheets such that the face sheets overlap the width of said core material around the perimeter of the device for enclosing and sealing the core material there within.

Abstract: A method of forming pellets or agglomerates of high density boron nitride from high purity hexagonal boron nitride by crushing the high purity hexagonal boron nitride into boron nitride particles extending over a size range of at least 100 microns with the majority of the particles having a particle size above 50 microns and cold pressing the crushed particles into a compacted form. The compacted form is then granulated into a granulated powder and again cold pressed to form pellets or agglomerates of boron nitride particles with the operations of cold pressing and granulation occurring in one or more stages.

Abstract: A coated article of a stoichiometric coating composition of pyrolytic PB(Si)N on low thermal expansion carbon, graphite or ceramic materials and process of forming the coated article. The process involves introducing reactant vapors, under appropriate deposition conditions, within a heated furnace chamber containing the article to be coated. The reactant vapors are composed of ammonia, a gaseous source of boron and silicon and a diluent gas and are fed at a gas flow rate such that the combined flow rate of boron and silicon is less than the flow rate of ammonia.

Abstract: A method of forming pellets or agglomerates of high density boron nitride from high purity hexagonal boron nitride by crushing the high purity hexagonal boron nitride into boron nitride particles extending over a size range of at least 100 microns with the majority of the particles having a particle size above 50 microns and cold pressing the crushed particles into a compacted form. The compacted form is then granulated into a granulated powder and again cold pressed to form pellets or agglomerates of boron nitride particles with the operations of cold pressing and granulation occurring in one or more stages.

Abstract: This invention is directed to a composite composition of particles of highly oriented graphite in the form of flakes having a hexagonal crystal orientation and an aspect ratio of at least 5 to 1 and a polymeric binder which when polymerized under compression forms a solid having a high thermal conductivity and low density and to a method of forming a machinable composite of high thermal conductivity comprising the steps of combining particles of highly oriented graphite flakes having an hexagonal crystal orientation and an aspect ratio of at least 5 to 1 with a polymeric binder to form a composition having at least a 40% graphite particle volume fraction, compressing the composition under a pressure sufficient to substantially align the particles parallel to one another and to the surface of the composition normal to the direction of the applied pressure until said binder polymerizes into a solid thereby forming an electrically conductive solid having a high thermal conductivity.

Abstract: This invention is directed to a method for shifting the mosaic spread of highly oriented pyrolytic graphite ("HOPG") into a preselected narrow range. The method involves selecting HOPG samples having a mosaic spread which lies below a desired mosaic spread range and cold working the selected samples to form a textured surface sufficent to shift the mosaic spread of the samples into the desired mosaic spread range. The textured surface is preferably imprinted by pressing the samples between metal dies with at least one of the dies having a knurled surface.

Abstract: An electrostatic chuck and method for electrostatically clamping a working member such as a semiconductor wafer to the chuck. The elcetrostatic chuck includes at least one conductive electrode and an insulating layer for separating the conductive electrode from the working member. The insulating layer is composed of a composition containing pyrolytic boron nitiride (PBN) and a carbon dopant in an amount above 0 wt % and less than about 3 wt % such that its electrical resistivity is smaller than 10.sup.14 .OMEGA.-cm. A source of voltage is impressed across the conductive electrode to generate an electrostatic field which causes the working member to be clamped to the chuck.

Abstract: In accordance with the present invention a pyrolytic boron nitride compact having an electrical resistivity smaller than about 10.sup.14 .OMEGA.-cm is formed by the process of introducing a feed gas of gaseous boron halide and ammonia at a suitable ratio into a furnace heated to a temperature between 1600.degree. C. to 2200.degree. C. with the furnace containing a substrate of graphite to form a deposit of pyrolytic boron nitride upon said substrate, substantially simultaneously introducing a hydrocarbon gas into the furnace to form a codeposit of carbon in the crystal structure of the pyrolytic boron nitride deposit, controlling the mole fraction of said hydrocarbon gas to limit the concentration of carbon to less than about 3 wt % of the pyrolytic boron nitride composition.

Abstract: The present invention relates to a boron nitride composition of particles of boron nitride and a nonionic surfactant for use as a filler with a distribution of agglomerates having an average particle size in the range of between 20-80 microns and to a molding compound having a high thermal conductivity of above at least 5 W/m.degree. K. The molding compound comprises a polymer base material, a filler and a nonionic surfactant with the filler comprising boron nitride in a concentration of at least 60% by weight of said composition and wherein the nonionic surfactant is selected from the class consisting of carboxylic acid amides and carboxylic acid esters.

Abstract: Boron nitride formed to an optimum density and composition of soluble borates and oxygen forms a material which deforms under pressure and reforms to make a very low permeability seal. The boron nitride seal is formed by precompacting a boron nitride powder having a soluble borate concentration of between 0.5 and 1.90% by weight, hot pressing the powder to a density of about 1.85 g/cc and machining the hot pressed powder into a seal of desired shape.

Abstract: A resistant heated flash evaporator including a body of any desired geometry having two opposite open sides, a cavity which forms a continuous open area extending from each of the two opposite sides and at least one metal evaporating surface facing the open area for evaporating metal laterally through the opposite sides of the cavity. The body is preferably composed of graphite and has a coating of pyrolyric boron nitride extending over a substantial portion of the body and over the metal evaporating surface formed by the cavity.

Abstract: A refractory boat formed from an intermetallic composite comprising titanium diboride and boron nitride or titanium diboride, boron nitride and aluminum nitride and further including a metal selected from molybdenum, tungsten, tantalum and niobium and an oxide of CaO or Y.sub.2 O.sub.3 with the minimum concentration of oxide of from 0.7 wt % and with a maximum combined concentration of metal and oxide not exceeding 20 wt %. The invention is also directed to a method for forming a hot pressed refractory boat of an intermetallic composite composition as indicated above which is hot pressed at about 1900.degree. C.

Abstract: An improved interface coating for a fibrous material composed of a silicon-containing boron nitride having the general composition BSi.sub.x N.sub.1+1.33x, and containing from 2 wt % to 42 wt % of silicon, with substantially no free silicon present. The coating is formed by CVD using reactant vapors of ammonia and a gaseous source of both boron and silicon which flow into the furnace chamber at a controlled flow ratio to nitride the deposit to form the complex coating.