Casting metals

Abstract

The casting of metals or salt and products made by casting metals or salts are described. For example, a method for casting metals or salts includes evacuating a mold that is pressurized with an inert gas and coupled to a pressurized source of molten metal or salt, wherein the pressurization of the source is sufficiently high to drive the molten metal or salt into the mold in response to the evacuation.

What is claimed is: 
     
         1 . A method for casting metals or salts, the method comprising:
 evacuating a mold that is pressurized with an inert gas and coupled to a pressurized source of molten metal or salt, wherein the pressurization of the source is sufficiently high to drive the molten metal or salt into the mold in response to the evacuation.   
     
     
         2 . The method of  claim 1 , wherein evacuating the mold comprises coupling the mold to a vacuum chamber, wherein the vacuum chamber has a volume that is 10 to 100 time a volume of the mold. 
     
     
         3 . The method of  claim 1 , wherein the source of molten metal or salt is pressurized to a pressure of less than 0.2 MPa gage or less. 
     
     
         4 . The method of  claim 1 , wherein the source of molten metal or salt is pressurized with the inert gas. 
     
     
         5 . The method of  claim 1 , wherein the mold is configured to cast a coil. 
     
     
         6 . The method of  claim 1 , wherein the mold is evacuated in 0.1 seconds or less. 
     
     
         7 . The method of  claim 1 , wherein:
 prior to the evacuation, the pressurization of the interior of the mold and the pressurization of the source are comparable and molten metal or salt is exposed to the inert gas pressurizing the mold.   
     
     
         8 . The method of  claim 1 , further comprising:
 during the evacuation, after the evacuation, or both during and after the evacuation, increasing pressurization of the source of molten metal or salt.   
     
     
         9 . The method of  claim 1 , wherein the mold comprises a core, multiple slides, or both a core and multiple slides. 
     
     
         10 . The method of  claim 9 , wherein the mold comprises a gas-permeable core and wherein evacuating the mold comprises evacuating at least part of the mold by drawing gas through the gas-permeable core. 
     
     
         11 . The method of  claim 1 , wherein the pressurized source comprises a crucible that includes resistive or inductive heating elements integrated therein or disposed along a surface thereof. 
     
     
         12 . A coil comprising:
 a cast unitary metal strip covered by an insulator and layered to form a plurality of turns about an axis, the metal strip having a width generally perpendicular to the axis and a height generally parallel to the axis, wherein the width is larger than the height.   
     
     
         13 . The coil of  claim 12 , wherein the cast unitary metal strip has a generally rounded rectangular cross-section parallel to the axis. 
     
     
         14 . The coil of  claim 12 , wherein the insulation of adjacent turns of the metal strip contact each other over substantially the entire width of the metal strip. 
     
     
         15 . The coil of  claim 12 , wherein the coil displays physical characteristics that are characteristic being cast in a relatively low pressure difference casting process. 
     
     
         16 . The coil of  claim 15 , wherein the physical characteristics include dimensions of microbubbles in the coil. 
     
     
         17 . The coil of  claim 12 , wherein the coil displays physical characteristics that are characteristic being cast directly in a shape that is nearly suitable for use, for example, wherein the metal strip is free from stress-induced microdefects resulting from an application of a force perpendicular to the axis to shape the metal strip. 
     
     
         18 . The coil of  claim 12 , wherein the metal strip comprises aluminum and the insulator comprises aluminum oxide. 
     
     
         19 . The coil of  claim 12 , wherein the cast unitary metal strip coil has a generally trapezoidal cross section parallel to the axis, wherein the cross section is oriented to intersect comparable cross sections of other coils of a motor or generator arranged generally concentrically about a center. 
     
     
         20 . The coil of  claim 20 , wherein the generally trapezoidal cross section is formed by a single winding of the cast unitary metal strip. 
     
     
         21 . The coil of  claim 12 , wherein, in at least one cross section parallel to the axis, regions of the cast unitary metal strip have non-uniform widths. 
     
     
         22 . The coil of  claim 21 , wherein the regions progressively increase or decrease in width along the axis. 
     
     
         23 . The coil of  claim 21 , wherein, in the at least one cross section parallel to the axis, regions of the cast unitary metal strip have non-uniform heights, for example, wherein the regions progressively increase or decrease in height along the axis. 
     
     
         24 . The coil of  claim 12 , wherein the coil is cast in an extended shape that forms a plurality of turns about an axis with a space between adjacent turns, for example, wherein the space between adjacent turns is 5 to 10 times wider than the thickness of the metal strip along the axis.