US 5,298,337 A · Perforated plates for cryogenic regenerators and method of fabrication

Abstract

Perforated plates (10) having very small holes (14) with a uniform diameter throughout the plate thickness are prepared by a "wire drawing" process in which a billet of sacrificial metal is disposed in an extrusion can of the plate metal, and the can is extruded and restacked repeatedly, converting the billet to a wire of the desired hole diameter. At final size, the rod is then sliced into wafers, and the wires are removed by selective etching. This process is useful for plate metals of interest for high performance regenerator applications, in particular, copper, niobium, molybdenum, erbium, and other rare earth metals. Er.sub.3 Ni, which has uniquely favorable thermophysical properties for such applications, may be incorporated in regions of the plates by providing extrusion cans (20) containing erbium and nickel metals in a stacked array (53) with extrusion cans of the plate metal, which may be copper. The array is heated to convert the erbium and nickel metals to Er.sub.3 Ni. Perforated plates having two sizes of perforations (38, 42), one of which is small enough for storage of helium, are also disclosed.

Claims22

Dependent claims

A process for making perforated plates having holes with a uniform diameter throughout the thickness thereof which comprises:

providing a first extrusion can of a selected plate metal;
disposing a cylindrical billet of a selected sacrificial metal within said can and in axial alignment with the can;
extruding or drawing the billet-containing can whereby the can and billet are elongated and reduced in diameter;
stacking a plurality of reduced-diameter, extruded or drawn billet-containing cans in a second extrusion can of said plate metal, with the extruded or drawn cans in axial alignment with one another and with the second can;
extruding or drawing the second can whereby the sacrificial metal billets therein are further elongated and reduced in diameter to form wires;
repeating said stacking and drawing or extrusion steps a plurality of times until the diameter of said wires is reduced to correspond to a desired perforation diameter;
slicing the resulting final extruded or drawn can perpendicular to the axis thereof to obtain wafers of a desired thickness;
and
selectively etching the wafers to remove the sacrificial metal wires whereby holes through the wafers are produced.

6 more elements

A process for preparing a composite perforated plate comprising a perforated matrix of a selected plate metal and inclusions of Er.sub.3 Ni which comprises:

providing a first extrusion can of said plate metal;
disposing a cylindrical billet of selected sacrificial metal in said can in axial alignment with the can;
extruding or drawing the billet-containing can whereby the billet and can are elongated and reduced in diameter;
stacking a plurality of reduced-diameter, extruded or drawn billet-containing cans in a second extrusion can of said plate metal, with the extruded or drawn cans in axial alignment with one another and with the second can;
extruding or drawing the second can whereby the sacrificial billets therein are further elongated and reduced in diameter;
stacking a plurality of extruded or drawn cans containing wires of sacrificial metal having a predetermined diameter in a third extrusion can in alternating relation with elongated solid bodies of the same size as the extruded cans and containing erbiumn and nickel metals in intimate contact with one another;
extruding or drawing said third can whereby said plate metal is merged with said elongated bodies, and said wires are further reduced in diameter;
heating said extruded or drawn third can at a temperature of 565.degree. C. to 800.degree. C. where said erbium and nickel react to form Er.sub.3 Ni;
slicing the heated can into wafers of a desired thickness;
and
etching the wafers to remove said sacrificial metal.

8 more elements

Dependencies are inferred from the claim text.

Perforated plates for cryogenic regenerators and method of fabrication

Life of this patent

Perforated plates for cryogenic regenerators and method of fabrication

Life of this patent

Abstract

Claims22