FR2625496A1 - PROCESS FOR MANUFACTURING FASTENED CARBON FIBER BODIES OR THE LIKE, AND ITS APPLICATION, IN PARTICULAR FOR BRAKE OR OTHER DISCS - Google Patents

Abstract

a) A method of manufacturing shaped bodies, made of carbon fiber, or the like, and its application in particular for brake discs or the like. b) A method characterized in that a crude part is shaped into duromer and that the latter is provided with a cover which is solid under pressure and adapted to the shape, which is permeable for the hydrogen gas which is formed by porosity or by openings, in which the blanket consists of a material which has at elevated temperatures a large hydrogen diffusion coefficient and then a pressure between 10 and 5000 bar and a temperature between 600 and 1000 degree (s) C is applied for a period of 10 to 40 hours. c) The invention relates to a process for manufacturing shaped bodies, made of carbon fiber or the like, and its application in particular for brake discs or the like.

Description

l Process for manufacturing shaped bodies made of carbon fiber, or

  analogous, and its application, in particular for

brakes or others.

  The invention relates to a method for producing molded bodies based on glassy carbon or reinforcing carbon.

carbon fiber (CFC).

  The production of shaped bodies based on

  vitreous bone is known. For this purpose, a rough part is

  from a duroplastic pre-material such as an epoxide,

  10 a polyimide or preferably a resin and the plyimides in particular

  ticular. Thanks to a heat treatment up to about 1000 C under vacuum or under protective atmosphere with a pressure

  up to about 10 bar the portion is converted to carbo-

  do not glassy. This porous part can then be soaked

  with a fluid resin, after complete hardening of the

  sine and new treatment by the chain, the density increases

  and by repeatedly repeating this step, a

  the density and solidity can be obtained in a suf-

  cient. Similarly, a process for producing carbon reinforced with carbon fibers (CFC) is known, in which

  a rolling product is created which consists of

  carbon heads directed in the desired direction and a

  duroplastic sine. After pressing and complete hardening of the rolling product which thereby obtains the final outline of a

  already extensively, a heat treatment is carried out.

  So here the piece again is soaked with the resin and again

  coked veal. This way we can achieve

  their density up to about 1.7 q / cm3. In a way

  alternative carbon reinforced by carbon fibers

  (CFC) can be obtained by gas phase filtration.

  In this process of preparation, the fact that extremely long process times are required, produces a

  disadvantageous effect. Thus according to the wall thickness of the

  this fashioned, the heat treatment cycle lasts for days to

  weeks, so that the total times can be

  to several months, when the process of imbibition by the

  resin should be repeated a few times.

  Another disadvantage must be seen in that the resulting shaped parts have thicknesses

  wall thickness greater than a few mm a certain porosity re-

siduelle.

  The problem of the invention is therefore to

  a process that speeds up the production of vitreous carbon or CFC shaped parts in a major way and makes it more economical. According to the invention the problem is solved in that a rough part based on a durometer is formed and that one is provided with a cover adapted to the shape and solid to the

  pressure, which is permeable due to porosity and

  vertures, for the gaseous hydrogen that has formed, in which

  the cover consists of a material that has

  tures, a significant hydrogen diffusion coefficient

  both, and then a pressure of between 30 and 5000 bar and a temperature between 600 and 1000 C for a period

from 10 to 40 hours are applied.

  Thanks to the process according to the invention, it is obtained that, as a result of the high temperatures, the hydrogen bonds of the hydrocarbons contained in the resin are broken and that

  the hydrogen atoms unite with the molecules of hydrogen.

  The resulting hydrogen gas, diffuses on the outer wall

  of the shaped piece. Depending on the execution of the cover, the

  gaseous drogen continues to diffuse through the blanket and

  through appropriate openings in the cover

  ture, outward in the surrounding atmosphere. In shaped parts only the carbon and other elements present in the resin remain. The external pressure applied to the shaped part simultaneously leads to a densification of the workpiece, so that vitreous carbon parts or

  CFCs can be produced in a short time. We can get qra-

  this process according to the invention a cycle time of 10 to 40 hours

  about so that the manufacturing time, the times of

  machine and high heating costs can be lowered.

  Preferably the cover consists of a

  a material which manifests at high temperatures significant hydrogen diffusion coefficients. A material which fulfills this requirement in a total temperature range or, for example titanium, only at elevated temperatures can be selected depending on requirements. In a preferred embodiment the

  cover of the shaped part will be closed on all sides to the

  vance. As a result of the hydrogen gas that forms inside

  of cover during heating there is a surplus

  which, however, because of the applied pressure of the former

  the surrounding atmosphere does not lead to any destruction

coverage.

  In an alternative embodiment, the cover

  ture is provided at appropriate places with openings for the

  passage of the hydrogen that is formed. For example, during the pro-

  duction of flat molded parts (trays, etc ...) the cover

  ture can be constituted in a simple way, of the two pistons

of a press.

  Therefore, it is not necessary that the pistons allow the diffusion of hydrogen, the more the gap that remains between the pistons is sufficient to evacuate the hydrogen gas that forms the shaped part. For plates made in this way the edging area must then be eliminated. In order for a diffusion of the qygous hydrogen from the inside of the shaped body into the surrounding atmosphere to occur, a partial pressure oradient is required.

  be present on both sides of the cover. So that this

  of partial pressure which is automatically present initially, also remains constant for hydrogen

  growing in the surrounding atmosphere, it is born

  necessary, especially for small volumes of

  environment, to plan operations that will eliminate

the hydrogen gas recovered.

  Preferably this occurs through

  of a device that is able to chemically untie

  hydrogen gas (absorber) or "Getter". The atmosphere around-

  This purpose is carried out by means of the active material of the absorber which, preferably, must be a compound of

  Titanium. In a further preferred development of the

  given following the step of the current process, a

  In this way, it is possible to crystallize the carbon structure of the amorphous shaped body remaining after the removal of the hydrogen, in an oraphite assembly and

  thus to increase the strength of it.

  In the embodiment with a vacuum impervious cover, it is also possible, in place of

  resins or duromers, to introduce thermoplasts. Because of

  its high temperatures these will certainly be liquid, however a fixed form cover ensures the conservation

  of the form requested. Alternatively, we can use

  instead of the carbon fibers of the Si-C fibers for

  which inorganic mineral resin used contains simul-

  at the same time Carbon and Silicon. In this way, one can

  obtain a shaped piece of Si-C reinforced with Si-C fibers.

R F V E N D I C A T I 0 N S

  1. Process for manufacturing molded bodies based on glassy carbon or fiber-reinforced carbon

  carbon fiber (CFC) characterized in that a raw portion is

  Durometer and that it is provided with a solid cover to the pressure and adapted to the shape, which is permeable

  for hydrogen gas which is formed by porosity or by openings

  tures, in which the cover consists of a material which pos-

  at high temperatures a diffusion coefficient at

  the important drogen and then a pressure between 10 and 500 bar and

  a temperature between 600 and 1000 C is applied during one

from 10 to 40 hours.

  20. The process as claimed in claim 1, characterized in that the covering consists of a material which exhibits at high temperatures a diffusion coefficient with respect to

the important hydrogen.

  3. Process according to Claim 2, characterized

  in that the material for the cover is titanium.

  4. Process according to Claim 1, characterized

  in that the blanket is closed in advance on all sides.

  50. Process according to any one of the

  cations 1 to 4 characterized in that the cover is eliminated

  after heat treatment in a chemical and / or

  mechanical. 6. Method according to claim 1, characterized

  in that the cover has openings at designated locations

  properties for the passage of hydro gas that is formed.

  70. The method of claim 6 characterized in that the cover consists of two pistons of a press to

  high temperature and the opening is the window between the pistons.

  8. Process according to any one of the

  cations 1 to 7 characterized in that the cover is deformable

  for the balance of diminishing masses.

  9. Process according to any one of the

  in which measures must be provided which guarantee the maintenance of the gradient of

  partial pressure of hydrogen on both sides of the blanket

ture.

  ] 0. Process according to claim 9,

  in that the partial pressure gradient is maintained

  by chemical bonding of the qazeux hydroqene.

  311. The method of claim 9, characterized

  in that the material of the absorber "Getter" is a com-

posed titanium.

  12. Process according to any one of the

  to 8, characterized in that a correlation

  citation of graphite is brought to red at temperatures

between R1800 and 2000 C.

  13. Process according to any one of

  I and 4, characterized in that, instead of residing

  nes or duromers, thermoplastics are used.

  34. Process according to any one of

  preceding claims, characterized in that instead of carbon fibers, Si-C fibers are used and that the

  Organic resin contains carbon and silicon.

  ] 5. Application of the process according to any one

  conque of claims 1 to] 4 to the manufacture of disks

  of brakes for aircraft or motor vehicles, for turbine or turbine control mechanism thrust nozzle valves

rocket.