Rotary sealant abradable material and method for making

DETAILED DESCRIPTION What I claim as new and desire to secure by Letters Patent of the United States is: 1.
A method for making a shaped abradable mass useful as a rotary sealant comprising (1) mixing together by weight from 60% to 80% of silicon powder having an average particle size with 20% to 40% of carbon fiber having a length to diameter ratio with average value of from 1 to 20 and from 5% to 20% of an organic binder based on the weight of mixture, (2) shaping the mixture of (1) under heat and a pressure of up to 2000 psi to produce a preform and (3) molding the preform of (2) under reduced pressure at a temperature in the range of 1500.
degree.
C.
to 1800.
degree.
C.
2.
A method in accordance with claim 1, where the binder is paraffin wax.
3.
A method in accordance with claim 1, where the carbon fiber is obtained from a carbon felt cloth.
4.
Rotary sealant material which is readily machinable and has a density of from 1.
1 to 1.
3, comprising the reaction product of 20% to 40% by weight of carbon fiber whose length to diameter ratio has an average value of from 1 to 20 and 60% to 80% by weight silicon powder having an average diameter of from 25 microns to 200 microns.




Description:
The present invention relates to a method for making abradable material useful as rotary sealant on turbine buckets and aircraft engine.
More particularly, the present invention relates to a method for making rotary sealant by heating a shaped blend of carbon fiber and silicon powder in a non-oxidizing atmosphere under reduced pressure to a temperature sufficient to convert the silicon powder to the molten state.
Prior the present invention, rotary seals used in various parts of power producing apparatus, such as gas turbines, were made by various procedures, such as shown by Butts U.
S.
Pat.
No.
3,383,207 and Daunt U.
S.
Pat.
No.
3,547,455.
An abradable material was used to provide a seal between a rotating member and a stationary member to inhibit fluid flow between such members.
Some of the abradable materials were based on the use of an epoxy resin and certain hollow organic particles having a bulk density of 3-5 pounds per cubic foot and an outside diameter of up to 0