Ceramic turbine wheel

Claim 1

A TURBINE WHEEL COMPRISING A UNITARY HUB-BLADE ASSEMBLY FORMED OF REACTION BONDED SILICON NITRIDE SO THAT ITS RADIAL CROSS SECTION TRANSVERSELY BETWEEN OPPOSING SURFACES THEREOF INCLUDES A RELATIVELY WIDE CROSS-SECTIONAL AREA EXTENDING SUBSTANTIALLY MORE THAN ONE-FOURTH INCH BETWEEN ITS OPPOSING OUTSIDE SURFACES AND INCLUDING MUTUALLY SPACED BUT INTERCONNECTED INDIVIDUAL PORTIONS THEREOF, WHEREIN THE OUTSIDE AND INSIDE SURFACES OF SAID RELATIVELY WIDE CROSSSECTIONAL AREA ARE SO SHAPED AND RELATIVELY DISPOSED THAT EVERY PART OF EACH INDIVIDUAL PORTION OF THE RELATIVELY WIDE CROSS-SECTIONAL AREA HAS AT LEAST ONE TRANSVERSE DIMENSION EXTENDING BETWEEN THE OPPOSING SURFACES THEREOF WHICH IS NO GREATER THAN ONE-FOURTH INCH.

Claim 5

A method of manufacturing a unitary hub-blade assembly comprising a turbine wheel from ceramic material including the sequential steps of compacting a quantity of fine silicon powder to a suitable external annular configuration for a hub-blade assembly comprising a turbine wheel including an annular portion thereof having a cross section from side to side thereof substantially in excess of one-fourth inch in thickness, providing in the hub-blade assembly of the turbine wheel at least one internally disposed radially extending annular recess of the necessary size and shape in relation to the size and shape of the respective sides of said annular portion to reduce the minimum cross section of the compacted silicon powder so that at every point on said annular portion at least one transverse dimension extending from surface to surface therof does not exceed one-fourth inch, exposing the compacted silicon powder to a nitrogen atmosphere at a temperature and for a time sufficient to convert all of the compacted silicon powder to silicon nitride.

Claim 6

A method of manufacturing a unitary hub-blade assembly comprising a turbine wheel from ceramic material including the sequential steps of compacting a quantity of fine silicon powder to a suitable external annular configuration for a hub-blade assembly comprising a turbine wheel including an annular portion thereof having a cross section from side to side thereof substantially in excess of one-fourth inch in thickness, providing in the hub-blade assembly of the turbine wheel at least one internally disposed radially extending annular recess of the necessary size and shape in relation to the size and shape of the respective sides of said annular portion to reduce the minimum cross section of the compacted silicon powder so that at every point on said annular portion at least one transverse dimension extending from surface to surface therof does not exceed one-fourth inch, exposing the compacted silicon powder to a nitrogen atmosphere at a temperature and for a time sufficient to convert all of the compacted silicon powder to silicon nitride.