Abstract: Carbon/carbon materials are joined together by the placement of a brazing alloy between the materials to be joined applying a clamping pressure and passing an electric current through the parts and brazing alloy until the brazing.multidot.k15H alloy melts and when allowed to solidify forms a unitary structure from the parts.

Abstract: The threaded split-bushing fastener assembly has been designed for high temperature applications such as on hypersonic vehicles. The fastener assembly consists of a pin (with a standard countersunk head at one end and a tapered end at the other end), a tubular threaded split-bushing, a nut, and a washer. Installation is accomplished by inserting the pin in the parts to be fastened, then slipping the washer and split-bushing on the tapered end of the pin and finally screwing the nut onto the split-bushing. Tightening of the nut allows preloading of the fastener assembly.

Abstract: The tapered split-bushing fastener has been designed for high temperature applications. The fastener consists of a pin (with a standard countersunk head at one end and a tapered end at the other end), a split tapered bushing, a washer and a sleeve with an internal taper. Installation is accomplished by inserting the pin in the parts to be fastened, then slipping the washer and the split bushing on the tapered end and finally pushing the sleeve onto the split bushing. Pushing the sleeve causes the split-bushing to react against the washer and generate the fastener axial preload. A high temperature adhesive is then injected to lock the fastener in place.

Abstract: First and second multi-stage cryogenic refrigerators each have a displacer driven by a common motor so that the displacers are substantially 180.degree. out of phase. The final stage of each refrigerator has a regenerator arranged in a heat exchange relationship with counterflow.

Abstract: The cryogenic refrigerator includes a movable displacer within an enclosure having first and second chambers of variable volume. A refrigerant fluid is circulated in a fluid path between said chambers and correlated with movement of the displacer. A spool valve controls introduction of high pressure fluid and low pressure fluid to said chambers in a manner so that such flow is correlated with the pressure difference across said valve.

Abstract: In a cryogenic refrigerator, a valve member reciprocates to control fluid to and from chambers of variable volume. The valve member is moved in one direction by a cam and in the opposite direction by a fluid spring.