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US 2001/0019752 A1Published application
Pressure gradient CVI/CVD apparatus, process and product
AssigneeThe BFGoodrich Company
InventorsMark J. Purdy, James W. Rudolph, Lowell D. Bok
Life of this patent
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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.
Claims90
A CVI/CVD process, comprising the steps of:
- partially densifying a porous structure within a CVI/CVD furnace by depositing a first matrix within said porous structure with a pressure gradient CVI/CVD process in which a first portion of said porous structure is subjected to a greater pressure than a second portion of said porous structure and said first portion has a greater bulk density gain than said second portion;
- and,
- subsequently densifying said porous structure by depositing a second matrix within said porous structure with at least one additional densification process in which said second portion has a greater bulk density gain than said first portion.
A CVI/CVD process, comprising the steps of:
- partially densifying a multitude of annular fibrous carbon structures within a CVI/CVD furnace by depositing a first carbon matrix within said annular fibrous carbon structure with a pressure gradient CVI/CVD process in which a first portion of each annular fibrous carbon structure is subjected to a higher pressure than a second portion of each annular fibrous carbon structure and said first portion has a greater bulk density gain than said second portion;
- and,
- subsequently densifying said multitude of annular fibrous carbon structures by depositing a second carbonaceous matrix within each annular fibrous carbon structure with at least one additional densification process in which said second portion has a greater bulk density gain than said first portion.
A CVI/CVD process, comprising the steps of:
- heating a porous carbon structure to a temperature of at least 1750° F.;
- heating a hydrocarbon reactant gas to a temperature of at least 1650° F.;
- partially densifying said porous carbon structure by forcing said reactant gas to pass through said porous carbon structure from a first portion of said fibrous structure to a second portion of said porous carbon structure, said first portion having a greater bulk density gain than said second portion;
- and,
- subsequently densifying said porous carbon structure by depositing a second matrix within said porous carbon structure with at least one additional densification process in which said second portion has a greater bulk density gain than said first portion.
2 more elements
A friction disk, comprising:
- a densified annular porous structure having a first carbon matrix deposited within said annular porous structure and a second carbon matrix deposited within said annular porous structure overlying said first carbon matrix, said densified annular porous structure having two generally parallel planar surfaces bounded by an inside circumferential surface and an outside circumferential surface spaced from and encircling said inside circumferential surface, a first circumferential portion adjacent said inside circumferential surface, and a second circumferential portion adjacent said outside circumferential surface, wherein said first and second circumferential portions are bounded by said two generally parallel planar surfaces, said second circumferential portion having at least 10% less of said first carbon matrix per unit volume relative to said first circumferential portion, said first carbon matrix and said second carbon matrix having a substantially rough laminar microstructure, and said first carbon matrix being more graphitized than said second carbon matrix.
A friction disk, comprising:
- a densified annular fibrous structure having a first carbon matrix deposited within said annular porous structure and a second carbon matrix deposited within said annular porous structure overlying said first carbon matrix, said densified annular porous structure having two generally parallel planar surfaces bounded by an inside circumferential surface and an outside circumferential surface spaced from and encircling said inside circumferential surface, a first circumferential portion adjacent said inside circumferential surface, and a second circumferential portion adjacent said outside circumferential surface, wherein said first and second circumferential portions are bounded by said two generally parallel planar surfaces, said second circumferential portion having at least 10% less of said first carbon matrix per unit volume relative to said first circumferential portion, said first carbon matrix and said second carbon matrix having a substantially rough laminar microstructure, and said first carbon matrix being more graphitized than said second carbon matrix;
- wherein thermal conductivity normal to said two opposing surfaces and crushed apparent density of said densified annular porous structure generally decrease in a radial direction from said inside circumferential surface to said outside circumferential surface.
A CVI/CVD process in a CVI/CVD furnace, comprising the steps of:
- introducing a reactant gas into a sealed preheater disposed within said CVI/CVD furnace, said sealed preheater having a preheater inlet and a preheater outlet, said reactant gas being introduced into said preheater inlet and exiting said sealed preheater through said preheater outlet and infiltrating at least one porous structure disposed within said CVI/CVD furnace;
- heating said at least one porous structure;
- heating said sealed preheater to a preheater temperature greater than said reactant gas temperature;
- sensing a gas temperature of said reactant gas proximate said outlet;
- adjusting said preheater temperature to achieve a desired gas temperature;
- and, exhausting said reactant gas from said CVI/CVD furnace.
3 more elements
The process of 64, wherein said stack defines an enclosed cavity bounded by said annular porous wall;
- and,
- further comprising the step of introducing said reactant gas from said preheater outlet into said enclosed cavity, said enclosed cavity being sealed to said preheater outlet.
A CVI/CVD process in a CVI/CVD furnace, comprising the steps of:
- forming an annular porous wall that defines an enclosed cavity, said porous annular wall including a stack of annular fibrous carbon structures;
- sealing said annular porous wall to a sealed preheater, said sealed preheater having a preheater inlet and a preheater outlet, said enclosed cavity being in fluid communication with said gas outlet;
- introducing a carbon bearing reactant gas into said preheater inlet, directing said gas through said sealed preheater, to said preheater outlet, and into said enclosed cavity;
- heating said annular porous wall;
- heating said preheater to a preheater temperature greater than a gas temperature of said reactant gas proximate said preheater inlet;
- sensing a gas temperature of said reactant gas proximate said preheater outlet;
- adjusting said preheater temperature to achieve a desired gas temperature;
- and, withdrawing said reactant gas from said CVI/CVD furnace on a side of said annular porous wall opposite said enclosed cavity thereby forcing dispersion of said reactant gas introduced into said enclosed cavity through said annular porous wall.
5 more elements
An apparatus for introducing a first reactant gas into a CVI/CVD furnace, comprising:
- a first main gas line for supplying the first reactant gas;
- a plurality of furnace supply lines in fluid communication with said first main gas line and the CVI/CVD furnace;
- a plurality of first flow meters that measure a quantity of first reactant gas flow through each furnace supply line;
- and,
- a plurality of first control valves configured to control said quantity of flow of the first reactant gas through each furnace supply line.
2 more elements
An apparatus for CVI/CVD densifying a plurality of porous structures, comprising:
- a CVI/CVD furnace that defines a furnace volume;
- a vacuum apparatus in fluid communication with said furnace volume;
- a first main gas line for supplying a first reactant gas;
- a plurality of furnace supply lines in fluid communication with said first main gas line;
- and,
- a plurality of stacks of the porous structures disposed within said furnace volume, each stack defining an enclosed cavity in fluid communication with a different furnace supply line and sealed within said furnace volume such that a reactant gas flow introduced into each enclosed cavity through said one furnace supply line is forced to disperse through said porous structures before being withdrawn from said furnace volume by said vacuum apparatus.
3 more elements
A CVI/CVD densification process, comprising the steps of:
- densifying a first porous wall within a CVI/CVD furnace by a pressure gradient CVI/CVD process wherein a first flow of reactant gas is forced to disperse through said first porous wall;
- densifying a second porous wall by a pressure gradient CVI/CVD process wherein a second flow of reactant gas is forced to disperse through said second porous wall;
- and,
- independently controlling said first flow of said reactant gas and said second flow of said reactant gas.
1 more element
Dependencies are inferred from the claim text.