Ultrasonic end-capping of beta"-alumina tubes
AssigneeFord Motor Company
InventorsAres N. Theodore, Robert A. Pett
Life of this patent
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Abstract
This invention comprises a method of ultrasonically end-capping a tubular green body which comprises a mixture of 40-60 volume percent sinterable beta"-alumina precursor particulate and 60-40 volume percent organic sacrificial binder wherein said sacrificial binder comprises a thermoplastic elastomer, a plasticizer which may be oil, wax or oil and wax, stiffening polymers, a processing aid and optional components. The tube is preferably formed by extrusion molding. The green body tube may be end-capped by ultrasonic forming or by ultrasonic bonding of an end-cap to the tube. During this process, ultrasonic vibration energy is dissipated as heat energy which melts the thermoplastic binder composition and welds the joining surfaces.
Claims29
A method of ultrasonically end-capping a tubular green body which comprises:
- (A) providing a tubular green body comprised of a mixture of about 40-60 volume percent sinterable particulate solids and 60-40 volume percent organic sacrificial binder, wherein said binder consists essentially of:
- (a) a thermoplastic block copolymer component selected from the group consisting of linear, radial and linear and radial block copolymers, having a first aromatic block which is glassy or crystalline at 20.degree.-25.degree. C., and which has a softening point between about 80.degree.-250.degree. C. and a second aliphatic block which is different from said first block and behaves as an elastomer at temperatures between about 15.degree. C. below and about 100.degree. C. above said softening point of said first block;
- (b) oil at least about 75 percent by weight of which boils in a range between about 285.degree.-560.degree. C., has a viscosity of between about 30-220 Saybolt Universal Seconds (SUS) at 100.degree. C., and has an Aniline Point in the range between about 75.degree.-125.degree. C.;
- (c) wax which melts at a temperature in a range between about 80.degree. C. and at least 75 percent by weight of which boils at temperatures in a range between about 315.degree.-490.degree. C.;
- (d) a first stiffening thermoplastic polymer which is glassy or crystalline at 20.degree.-25.degree. C., has a softening point between about 80.degree.-250.degree. C. and comprises aromatic monomeric units associable with the block copolymer (a);
- (e) a second stiffening thermoplastic polymer, different from said first polymer and which is glassy or crystalline at 20.degree.-25.degree. C. and comprising aromatic monomeric units associable with the first block and has a softening point below about 80.degree.-250.degree. C.
- (f) processing aid comprising an ester of fatty acids;
- and said sinterable particulate solids consisting essentially of a particle size distribution of beta"-alumina precursor particulate solids, the weight of (a) being greater than (b) and (c) combined, greater than (d) and (e) combined and greater than about two times (b), (c), (d), (e) or (f) alone;
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- (B) forming an end-cap of desired configuration having a composition comprising said mixture;
- (C) applying pressure and ultrasonic vibrations by means of an ultrasonic horn to said tubular green body and end-cap between a tubular mandrel and said ultrasonic horn, said mandrel having a shaped end of desired configuration and the ultrasonic horn having a female mold shape adapted to receive said mandrel with said tubular body disposed therein;
- (D) maintaining said pressure and ultrasonic vibrations for a time necessary for ultrasonic vibrations to travel to the tubular body end-cap interface, wherein they are dissipated in the form of frictional heat and melt said binder so as to weld the joining surfaces.
Dependencies are inferred from the claim text.