HIGH TEMPERATURE TURBINE BLADES

IRIDIUM-COATED RHENIUM THRUSTERS HAVE BEEN FABRICATED TO NETINTERNAL SHAPE BY CHEMICAL VAPOR DEPOSITION (CVD) FROM THE INSIDE OUT. THIS PROGRAM PROPOSES TO FABRICATE COATED HOLLOW NIOBIUM TURBINE BLADES TO NET EXTERNAL DIMENSIONS BY CVD ON THE INSIDE OF A HOLLOW MANDREL CONFORMING TO THE NET EXTERNAL SHAPE OF THE BLADE: AN OUTSIDE-IN PROCESS. AN OXIDATION-RESISTANT COATING OF SILICA, HAFNIA, OR IRIDIUM WOULD BE APPLIED FIRST, FOLLOWED BY A THICK DEPOSIT OF NIOBIUM OR NB ALLOY. THIS PROCESS ENSURES THE ACHIEVEMENT OF NET SHAPE FOR THE COATED BLADE; ALSO, CONTAMINATION OF THE NIOBIUM AT THE INTERFACE, AS A RESULT OF THE COATING DEPOSITION PROCESS AND TYPICALLY INVOLVING OXYGEN, HYDROGEN, CHLORINE, OR WATER, IS AVOIDED. THE RESULTING STRUCTURE SHOULD HAVE AN UNCOOLED OPERATING TEMPERATURE CAPABILITY OF 1500 DEGREE(C) (2730 DEGREE(F) OR HIGHER.