摘要:
A set of furnace spacers for spacing a first preform from a second preform, the first and second preforms each having an outer periphery, a width, an inner opening having a periphery and a width, a first side defined by the outer periphery and said inner opening, the first side having a surface area, and a second side spaced from the first side. Each spacer in the set of spacers has a body having a first side having a surface area, and the sum of the first side surface areas of the spacers in a set is greater than about thirty percent of the preform first side surface area.
摘要:
A template (10) configured for use with an annular preform (26) having a periphery (32) and an inner opening (34), the template (10) having an annular body with an outer periphery (16) and an inner opening (18) and a plurality of spacer openings (12) through its body each for receiving a spacer (25), one of the template inner opening (18) and the template outer periphery (16) having a width equal to the width of the preform inner opening (34) or the preform outer periphery (32). Also a method for densifying preforms that includes a step of positioning spacers using a template.
摘要:
A furnace spacer (10, 30, 50, 70) for spacing a first annular preform (22) from a second annular preform (22) in a furnace (100), each of the first and second annular preforms (22) having an outer periphery and a width and an inner opening having a periphery and a width, the spacer (10, 30, 50, 70) having an annular body (12, 32, 52, 72) having an inner diameter and an outer diameter. Also a method of alternately stacking spacers and preforms in a furnace.
摘要:
Apparatus such as a furnace muffle (11) for use in a CVI/CVD furnace. The apparatus includes a bottom (12), a top (13), and an outer wall (3) defining an interior space (1) in the apparatus, and a passive heat distribution element (7, 9) located within the interior space (1) and apart from the outer wall (3). Preferably, the bottom (12) and top (12) include perforated plates and the outer wall (3) is cylindrical in shape and all are made of graphite or carbon-carbon composite material and the passive heat distribution element (7, 9) is cylindrical in shape and includes graphite or carbon-carbon composite discs having no spacers therebetween. Also, a method for densifying a porous carbon preform (5), which method includes the steps of: (a) providing the apparatus (11); (b) charging the apparatus (11) with a plurality of stacks of annular porous carbon preforms (5), the preforms being separated from one another by spacers (15); (c) locating the charged apparatus (11) in a furnace at a temperature in the range of 950-1100° C. and a pressure in the range of 5-40 torr; and (d) circulating a natural gas reactant blended with up to 15% propane through the apparatus for 150-900 hours. Also, a batch of carbon-carbon composite preforms made by the method, wherein the density of the batch of preforms is at least 0.5 g/cc higher than the density of a batch of preforms made by an otherwise identical process in which the apparatus does not contain a passive heat distribution element located within its interior. The preforms may be configured as aircraft landing system brake discs or racing car brake discs.
摘要:
Method for densifying porous carbon preforms. The method including: providing an apparatus charged with at least one stack of annular porous carbon-carbon composite preforms, the preforms being separated from one another by spacers emanating from a passive heat distribution element centrally located within a cylindrical space formed by the stack of annular preforms; locating the charged apparatus in a furnace at a temperature of 950-1100° C. and a pressure of 5-40 torr; and circulating a carbon-containing gas reactant through the apparatus for 150 to 900 hours. Also, an apparatus for practicing this method. The preforms are densified with less physical damage due to the weight of the preforms being treated than are preforms made by otherwise identical processes that do not separate preforms from the preforms immediately above and below them by spacer elements comprising tabs or shelves emanating from a central passive heat distribution structural member.
摘要:
A gas preheater (10) that includes an exit plate (20) having first and second sides (22, 24) and a plurality of through holes (26) and at least one body (34) mounted adjacent the first side (22), the at least one body (34) having a first end (36) and a second end (38), the second end (38) located between the body first end (36) and the exit plate first side (22), at least one sidewall (40) connecting the first and second ends (36, 38), a body opening (42) in the first end (36) extending into the body (34) and defining a body inner wall (44), and a plurality of passages (46) extending between the at least one sidewall (40) and the body inner wall (44).
摘要:
Methods and apparatus to monitor a process of depositing a constituent of a multi-constituent gas are disclosed. The methods and apparatus may be used in a process for producing a carbon-carbon composite brake disc.
摘要:
A method and brake disc assembly to utilize worn refurbished brake material is disclosed. The method discloses the use of a brake disc for braking and the subsequent machining or refurbishment of the brake disc so that the brake disc can be used for three tours of braking to increase the utilization of the brake material.
摘要:
Method of manufacturing carbon-carbon composite brake disc by: (a) providing textile-based preform in shape of annular brake disc, the preform having a volume 30% or more greater than the volume of the brake disc to be manufactured; (b) subjecting the preform to a first CVD processing for not more than 7.5 days to density it to not more than 1.0 g/cc; (c) machining the densified preform to a shape having a volume no more than 15% greater than the volume of the carbon-carbon composite brake disc to be manufactured: and (d) subjecting the preform to one or two additional cycles of CVD processing, to further densify it to a density of more than 1.7 g/cc. The preform is then machined to provide the carbon-carbon composite brake disc. The total CVD processing time in steps (b) and (c) is no longer than about 32.5 days.
摘要:
Method of chemical vapor infiltration of a deposable carbon material into a porous carbon fiber preform in order to densify the carbon fiber preform. The method includes the steps of: situating the porous carbon fiber preform in the reaction zone; providing a linear flow of a reactant gas comprising deposable carbon material in the reaction zone at an initial reaction pressure of at most 50 torr to produce deposition of the deposable carbon material into the preform; and adjusting the pressure of the gas to reaction pressures lower than said initial reaction pressure while deposable carbon material continues to be deposited into the porous carbon fiber preform. This method enables attainment of a target increased density in a carbon fiber preform much more quickly than known processes. A programmed pressure swing throughout the CVI/CVD run may be set in order to provide a linear increase in density. Alternatively, step changes in pressure during the course of the densification process may be made to enhance the rate of densification. This method reduces the number of cycles and the required intermediate machining steps necessary to densify preforms.