Abstract: 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).

Abstract: 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.

Abstract: Method for densifying a porous carbon preform (5). The 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 a period of from 150 to 900 hours. Carbon-carbon composite preforms made by this method may be configured as aircraft landing system brake discs or racing car brake discs.

Abstract: 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).

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.