Abstract: A method of manufacturing a carbon structure can comprise: infiltrating the carbon structure with a silicon oxycarbide (SiOC) precursor sol; and densifying the carbon structure by chemical vapor infiltration (CVI) to form a carbon and ceramic matrix composite material, the carbon and ceramic matrix composite material comprising between 0% and 15% by weight of a plurality of ceramic particles from the ceramic compound, densifying the carbon structure including adjusting a temperature gradient across the carbon structure.

Abstract: A method for manufacturing a C/C part includes fabricating an oxidized PAN fiber preform comprising a stack of sheets of multi-axial, non-crimp, OPF fabric. The method includes positioning the oxidized PAN fiber preform with a female forming tool, the female forming tool comprising a die recess, and forming the oxidized PAN fiber preform into a shaped body. The shaped body is removed from the female forming tool and moved into a graphite fixture for carbonization. The carbonized shaped body may also be densified into the final C/C part. The carbonized shaped body can also be placed in a perforated graphite fixture for densification and removed from the perforated graphite fixture between densification processes for machining and for facilitating further densification.

Abstract: A method of densifying an annular porous structure comprises stacking a plurality of annular porous structures to form a porous structure stack in a graphite susceptor, wherein the graphite susceptor is disposed within a vessel. The method includes disposing a graphite panel within the graphite susceptor and located radially inward from the porous structure stack. The method includes flowing a reactant gas into the vessel.

Abstract: A method of densifying an annular porous structure comprises stacking a plurality of annular porous structures to form a porous structure stack in a graphite susceptor, wherein the graphite susceptor is disposed within a vessel. The method includes disposing a graphite panel within the graphite susceptor and located radially inward from the porous structure stack. The method includes flowing a reactant gas into the vessel.

Abstract: A method and apparatus for decreasing the radial temperature gradient in CVI/CVD furnaces is provided. The apparatus may comprise a graphite susceptor disposed within a vessel. Porous structures may be stacked within the graphite susceptor. The stack of porous structures may form a circular shape proximate a radially inward surface of the graphite susceptor. Graphite panels may be disposed within the graphite susceptor. The graphite panels may be located proximate a radially inward surface of the porous structures. The graphite panels may radiate heat radially outward and towards the graphite susceptor. Reactant gas may be flowed into the graphite susceptor.

Abstract: A method and apparatus for decreasing the radial temperature gradient in CVI/CVD furnaces is provided. The apparatus may comprise a graphite susceptor disposed within a vessel. Porous structures may be stacked within the graphite susceptor. The stack of porous structures may form a circular shape proximate a radially inward surface of the graphite susceptor. Graphite panels may be disposed within the graphite susceptor. The graphite panels may be located proximate a radially inward surface of the porous structures. The graphite panels may radiate heat radially outward and towards the graphite susceptor. Reactant gas may be flowed into the graphite susceptor.

Abstract: A process for densifying porous structures inside a furnace using non-pressure gradient CVI/CVD includes disposing a number of porous structures in a stack within a furnace. The stack has a center opening region extending through the porous structures and an outer region extending along the outside of the porous structures. Channels provide fluid communication between the center opening region and the outer region. A first portion of a gas composition is introduced to the center opening region. A second portion of the gas composition is introduced to the outer region. The porous structures are densified from an average density of less than 0.60 g/cm3 to an average density of greater than 1.70 g/cm3 in a single cycle of non-pressure gradient CVI/CVD.

Abstract: A pressure gradient CVI/CVD process includes providing a furnace defining an outer volume. Porous structures and ring-like spacers are assembled in a stack with a ring-like spacer between each adjacent pair of porous structures. The stack of porous structures is disposed between a bottom plate and a top plate in the furnace, wherein the bottom plate, the stack of porous structures, and the ring-like spacers define an enclosed cavity. A channel provides fluid communication between the enclosed cavity and the outer volume. A gas composition is introduced into the enclosed cavity. A portion of the gas composition flows through the channel. A pressure gradient is maintained between the enclosed cavity and the outer volume. The gas composition in the outer volume is provided at a pressure of at least about 15 torr. The porous structures are densified.

Abstract: A method for densifying porous structures inside a furnace using non-pressure gradient CVI/CVD in a single cycle is described. A hardware assembly for use in the single cycle non-pressure gradient CVI/CVD process is provided as well are process and process conditions are described.

Abstract: A method of chemical vapor infiltration and deposition includes stacking a number of porous structures in a stack in a furnace. The stack has a center opening region extending through the porous structures and an outer region extending along the porous structures. A first portion of a reactant gas is introduced to the center opening region. A second portion of the reactant gas is introduced to the outer region. The first portion and the second portion are controlled proportions thereby introducing predetermined portions of the reactant gas to both the center opening region and the outer region. The change in weight of the entire furnace, including contents, is measured during the chemical vapor infiltration and deposition process. The rate of weight change is monitored.

Abstract: An apparatus and method for densifying porous structures inside a furnace using pressure gradient CVI/CVD. The apparatus includes a stack of porous structures where each porous structure has an aperture therethrough. The apparatus also includes at least one ring-like spacer disposed within the stack of porous structures between neighboring porous structures. The ring-like spacer encircles the apertures of the neighboring porous structures. The stack of porous structures and the at least one ring-like spacer define an enclosed cavity including each porous structure aperture. A channel provides fluid communication between the enclosed cavity and an outer volume defined by the interior surface of the furnace.

Abstract: The invention relates to pressure gradient processes for forcing infiltration of a reactant gas into a porous structure. The process comprises the steps of partially densifying a porous structure with a pressure gradient CVI/CVD process in which a first potion of the porous structure is subjected to greater pressure than a second portion of the porous structure. The process is suited for the simultaneous CVI/CVD processing of large quantities of aircraft brake.

Abstract: A method and apparatus for cooling a furnace configured for processing refractory composites comprising a cooling gas flowed in a closed circuit through the furnace and over a cooling element disposed within the furnace. The cooling gas can flow either by natural convection or a convective force.

Abstract: A hardware assembly is provided for controlling a first portion of gas and a second portion of gas in a furnace. The first portion of the gas is introduced to a center opening region of a stack of porous structures. The second portion of the gas is introduced to an outer region of the stack of porous structures. Most of the gas flows out of the hardware assembly from either the center opening region or the outer region while some of the gas flows out through small holes from the other region. A densification method is also provided with two densification processes in which the gas flows in opposite directions in the two densification processes.

Abstract: A hardware assembly is provided for controlling a first portion of gas and a second portion of gas in a furnace. The first portion of the gas is introduced to a center opening region of a stack of porous structures. The second portion of the gas is introduced to an outer region of the stack of porous structures. Most of the gas flows out of the hardware assembly from either the center opening region or the outer region while some of the gas flows out through small holes from the other region. A densification method is also provided with two densification processes in which the gas flows in opposite directions in the two densification processes.

Abstract: A method and apparatus for cooling a furnace configured for processing refractory composites comprising a cooling gas flowed in a closed circuit through the furnace and over a cooling element disposed within the furnace. The cooling gas can flow either by natural convection or a convective force.

Abstract: A hardware assembly is provided for controlling a first portion of gas and a second portion of gas in a furnace. The first portion of the gas is introduced to a center opening region of a stack of porous structures. The second portion of the gas is introduced to an outer region of the stack of porous structures. Most of the gas flows out of the hardware assembly from either the center opening region or the outer region while some of the gas flows out through small holes from the other region. A densification method is also provided with two densification processes in which the gas flows in opposite directions in the two densification processes.

Abstract: The invention relates to method and apparatus for cooling a furnace configured for processing refractory composites. More specifically, the invention is directed to method and apparatus for cooling a furnace more rapidly than prior art methods. According to the invention, a cooling gas is flowed in a closed circuit through the furnace, over the refractory composites disposed within the furnace, and over a cooling element disposed within the furnace. The cooling gas may be flowed by natural convection or by force.

Abstract: The invention relates to method and apparatus for cooling a furnace configured for processing refractory composites. More specifically, the invention is directed to method and apparatus for cooling a furnace more rapidly than prior art methods. According to the invention, a cooling gas is flowed in a closed circuit through the furnace, over the refractory composites disposed within the furnace, and over a cooling element disposed within the furnace. The cooling gas may be flowed by natural convection or by force.

Abstract: The invention relates to the field of high temperature composites made by the chemical vapor infiltration and deposition of a binding matrix within a porous structure. More particularly, the invention relates to pressure gradient processes for forcing infiltration of a reactant gas into a porous structure, apparatus for carrying out those processes, and the resulting products. The invention is particularly suited for the simultaneous CVI/CVD processing of large quantities (hundreds) of aircraft brake disks.