Ceramic-metal brazed joint for turbochargers

DETAILED DESCRIPTION What is claimed is: 1.
The method of joining a ceramic stub shaft to a metal shaft to form a torque transmitting joint suitable for use in high speed machinery comprising the steps of: forming a bore through a metallic sleeve member: forming an annular relief about said stub shaft; placing the ceramic stub shaft into one end of said bore; placing a predetermined amount of braze alloy into the bore such that it abuts the stub shaft; placing the metal shaft into the other end of the bore such that the braze alloy is between the ceramic shaft and metal shaft; heating the area generally about the braze alloy until melting occurs; allowing the braze alloy to flow around the ceramic shaft into said annular relief; and allowing the braze alloy to cool.
2.
The method according to claim 1 wherein the step of placing the metal shaft into the bore of the metallic sleeve member includes press fitting.
3.
The method according to claim 1 wherein the step of forming an annular relief includes machining a circumferential groove to a depth of from about 0.
0015" to about 0.
0030" about said stub shaft.
4.
The method according to claim 1 wherein the brazing operation takes place within an inert atmosphere and without the use of a flux material.
5.
The method according to claim 1 wherein said braze alloy is provided with a reactive component to develop a chemical bond with the ceramic.
6.
The method according to claim 1 further comprising the step of first welding a hub portion about one end of said sleeve member.
7.
The method of reducing the compressive forces acting on a ceramic shaft by a surrounding sleeve member comprising the steps of: forming an annular relief about said ceramic shaft; brazing the sleeve member to said ceramic shaft such that only a portion of said relief is brazed to said sleeve member.
8.
The method according to claim 7 wherein said annular relief is formed in a coaxial stub shaft integral with a ceramic rotor.
9.
The method according to claim 7 further including the step of selecting a predetermined amount of braze material just sufficient to fill only a portion of said relief