Abstract: A thermomechanical method for fabricating net shape single crystal airfoils is disclosed. A cast single crystal superalloy workpiece is solution heat treated to provide a homogeneous gamma prime distrubition. The single crystal sheet stock is then warm worked, generally forged or rolled, at a working temperature of gamma prime solvus minus about 50.degree.-300.degree. F. with a maximum six percent deformation per pass. Following the first warm working, the single crystal sheet stock is cyclic annealed in a temperature range of gamma prime solvus minus about 50.degree.-125.degree. F. to prevent recrystallization of the single crystal sheet stock. The cyclic annealing is preferably cycled three to ten times between the low and high ends of the temperature range at a rate of change of temperature between about 1.degree. F. per minute to about 10.degree. F. per minute.
Type:
Grant
Filed:
June 25, 1990
Date of Patent:
December 24, 1991
Assignee:
The United States of America as represented by the Secretary of the Air Force
Abstract: A structure for attenuating explosive shock waves to prevent propogation of accidental explosions by sympathetic detonation of adjacent explosives comprising bidirectionally symmetric layers of material of consecutively increasing or decreasing acoustic impedance laminated about a center layer. The structure may be made by combining several materials, as in consecutive layers of aluminum, plastic, and a rigid foam surrounding on both sides a layer of steel; or, two material, as in a center layer of Kevlar.TM. surrounded on both faces with layers of plastic. The plies comprising the layer of Kevlar.TM. are canted with respect to the plastic layers.
Type:
Grant
Filed:
May 6, 1988
Date of Patent:
February 5, 1991
Assignee:
The United States of America as represented by the Secretary of the Air Force
Abstract: A new method for making a heat pipe wick and arteries includes drilling. Radial holes around the circumference of the heat pipe container at its ends and stringing monofilament polymer lines inside the container between corresponding holes. The container is rotated at a slow rate while a slurry of nickel powder mixed into a viscous binder of water, Polyox and Methocel is injected inside the container to cover the inside surface of the container and the lines. The rotational rate of the container is then increased to force the slurry to level out to an uniform depth set by the thickness of sleeves attached at each end of the container. Forced air is blown through the inside of the rotating pipe to dry the slurry and form a green wick. After stopping rotation of the pipe, it is then heated inside a sintering oven in a reducing atmosphere to disintegrate the binder and polymer lines and to leave a sintered metal wick having hollow longitudinal arteries.
Type:
Grant
Filed:
October 24, 1988
Date of Patent:
May 29, 1990
Assignee:
The United States of America as represented by the Secretary of the Air Force