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Materials and methods for making ceramic matrix composites

a technology of ceramic matrix and composites, applied in the direction of friction lining, transportation and packaging, mechanical equipment, etc., can solve the problems of excessive wear, significant heat generation, damage to brake components, including parts,

Inactive Publication Date: 2005-12-15
SHERWOOD WALTER J +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0005] Ceramic matrix composites and fiber reinforced ceramic matrix composite components of brake systems and other friction tolerant composite articles of this invention are made by providing a fiber preform, coating the fibers with an interface layer of carbon or ceramic, infiltrating the coated fiber preform with a composition comprising a liquid ceramic forming polymer including friction controlling additives, and pyrolyzing the polymer in the infiltrated preform to form a ceramic matrix around the fibers of the preform. Important features of the invention include the use of near-stoichiometric silicon carbide forming matrix polymer formulations comprising particulate fr

Problems solved by technology

In high energy stopping, significant quantities of heat are generated by friction between the moving and fixed brake components.
Friction is necessary to slow and stop the vehicle.
When there is a high level of friction the heat generated can be sufficient to damage brake components, including parts other than the moving parts.
Excess wear, surface erosion, seizing, and fire are possible results of undissipated frictional heat.
In emergency stopping situations involving heavy equipment such as trains, trucks, and heavy aircraft, friction heat can completely destroy the brake system rendering it useless for control and necessitating extensive repair or total replacement.
Other components such as rubber wheels, hoses, hydraulic fluids, fuel tanks, and the like can ignite and burn.
The large amount of heat generated by friction can not be reduced or dissipated by air flow around the contact surfaces.
However, carbon / carbon brakes exhibit low friction characteristics until the contact surfaces get hot.
Should the need for an emergency quick stop arise before sufficient friction has built up, the airplane cannot be stopped.
They are porous and absorb moisture in humid environments leading to decreased performance.
The porous materials have been shown to be subject to contamination and property loss by de-icing and other fluids.
These materials oxidize at a temperature similar to that experienced during certain taxiing conditions, they generate corrosive dust, and they are very expensive to make.
The carbon rotors and carbon stators are formed by an infiltration process that is very expensive and literally takes weeks to accomplish.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

Brake Rotors and Stators for Aircraft

[0013] Needled carbon or graphite fiber felt with 20 to 50 percent fiber volume fraction, either pitch fiber or PAN fiber graphitized by heating to over 1400° C. using heat cycles commonly know in the carbon processing industry. The preform is cut to about 10%-15% larger than the desired dimensions of the end product. For an F-16 aircraft brake rotor, this is about 13.25″ outer diameter by 5.2″ ID by 0.9″ thick. A mixture of additives selected from the group comprising iron oxide, alumina, and silica powder having a size of size less than about 40 microns, and preferably less than about 10 microns is added during the process of forming the fiber felt preform. This is to provide uniform distribution of the additives throughout the rotor and stator. The addition of the additives during preform manufacturing also simplifies and lowers the cost of the follow-on densification process. A typical composition for an F-16 rotor size preform would be abou...

example 2

Brake Rotors and Pads for Heavy Trucks and Heavy Equipment

[0017] Needled carbon or graphite fiber felt with 20 to 50 percent fiber volume fraction either PAN fiber graphitized by heating to over 1400° C. using heat cycles commonly known in the carbon processing industry or pitch fiber. The perform is cut to roughly 10%-15% larger than the desired dimensions of the end product. For example a truck rotor might be 10″ OD with a 5″ ID and 0.625″ (⅝) thickness. Each rotor preform is treated with a 15-25 wt % (based on the weight of the preform) solution of SOC A500B in hexane. Once the solvent is evaporated off, the coated preform is heated in inert gas at a rate of 2 deg. C. per minute up to 850-1000° C. and held for one hour before being allowed to cool to room temperature.

[0018] A mixture of iron oxide, alumina, and silica powders of size less than 40 microns, and preferably less than 10 microns of typical composition for a 10 inch truck rotor size preform would be about 90 to 120 g...

example 3

[0021] Brake rotors and pads for racing vehicles, high end automobiles, and sport utility vehicles require temperature and friction resistance similar to the requirements for aircraft and heavy trucks. Brake rotors, pads can be formed in the same manner as described in Example 2. Alternatively, more traditional brake pad materials could be used. Specific examples include carbon loaded sponge iron, carbon rich semi-metallic pads, and sintered metal pads.

[0022] The broad range of operational environments covered in automotive applications make it impossible to describe each alternative. The key factors in selecting a pad will be desired wear life, desired friction coefficient, and noise vibration and harshness (NVH) requirements. Luxury suvs and passenger cars are designed to be quiet and smooth. For these reasons the selected pad would probably be a carbon loaded sponge iron like the FERODO DS3000 material. These pads are extremely quiet and smooth but have only moderately improved ...

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Abstract

Ceramic matrix composites and fiber reinforced ceramic matrix composite components of brake systems and other friction tolerant composite articles of this invention are made by providing a fiber preform, coating the fibers with an interface layer of carbon or ceramic, infiltrating the coated fiber preform with a composition comprising a liquid ceramic forming polymer including friction controlling additives, and pyrolyzing the polymer in the infiltrated preform to form a ceramic matrix around the fibers of the preform.

Description

[0001] This invention is directed to materials and methods for manufacture of ceramic matrix composites, including fiber reinforced ceramic matrix composites, for use in high temperature and high friction energy applications such as brake components for aircraft, heavy vehicles, racing vehicles, sports utility vehicles, and mechanical power transmission equipment. More particularly the invention is directed to ceramic composite materials and fiber reinforced composite materials having optimized friction coefficients for high energy applications and uses. The invention provides a major innovation in the ability to regulate and adapt the ceramic composition to changing friction requirements by choice or selection of the preceramic polymer and the type and amount of additive powders. BACKGROUND [0002] Vehicles are generally provided with braking systems for speed and for slowing moving vehicles. Brake systems generally comprise rotating components associated with the vehicle wheels and...

Claims

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Application Information

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IPC IPC(8): C04B35/571C04B35/80D04H1/00F16D69/02
CPCC04B35/571F16D2200/0047C04B2235/3217C04B2235/3272C04B2235/3418C04B2235/3826C04B2235/386C04B2235/3873C04B2235/3895C04B2235/422C04B2235/483C04B2235/5224C04B2235/5228C04B2235/524C04B2235/5244C04B2235/5248C04B2235/5436C04B2235/77C04B2235/80F16D69/023C04B35/806Y10T428/249924C04B35/80
Inventor SHERWOOD, WALTER J.ATMURR, STEVEN D.
Owner SHERWOOD WALTER J
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