Apparatus for Producing Silicone Carbide Articles and Articles Made Therewith

Abstract

Method for treatment of workpieces of porous carbon material with liquid silicon with the formation of silicon carbide, comprising the following steps: Preheating of porous carbon workpieces under an inert gas to a selected operating temperature T B 1, delivery of liquid silicon to the porous carbon workpieces at an operating pressure p B 2 and an operating temperature T B 2 and impregnation of the porous carbon workpieces with liquid silicon, reaction of the liquid silicon in the workpiece at a temperature T B 3 with formation of silicon carbide from carbon and silicon, gassing of the workpieces with inert gas, and cooling from the operating temperature T B 3 to a conditioning temperature T k , cooling of workpieces to room temperature, in step c the delivery of silicon and transport of the workpieces taking place over preferably cylindrical rolls which are porous at least in the exterior region and which are pivoted, and their speed of rotation determining the residence time for the delivery of silicon in step c, and the temperature T B 3 being greater than or equal to the temperature T B 2, and the workpieces for process step d no longer being in contact with liquid silicon outside the workpieces.

1 - 13 . (canceled) 
     
     
         14 . An apparatus for producing silicon carbide articles, comprising:
 means defining a plurality of closable chambers;   means for successively transporting porous carbon workpieces through said chambers;   means for preheating a porous carbon workpiece under an inert atmosphere in a first of said chambers, from room temperature to a first temperature;   means for impregnating a workpiece with molten silicon at a first pressure and a second temperature, in a second of said chambers, including a bath of molten silicon and a rotatable wick operable to convey molten silicon carbide;   means for heating said workpiece at a third temperature in a third of said chambers, allowing molten silicon having penetrated said workpiece to react with carbon thereof to form silicon from said bath to said workpiece;   means for heating said workpiece at a third temperature in a third of said chambers, allowing molten silicon having penetrated said workpiece to react with the carbon thereof to form silicone carbide; and   means for providing an inert gas in a forth of said chambers, allowing a continuation of said reaction and a reduction of stresses in said workpiece.   
     
     
         15 . An apparatus according to  claim 14  wherein said first temperature is in the range of 1300° C. to 1800°. 
     
     
         16 . An apparatus according to  claim 14  wherein said second temperature is in the range of 1450° to 1700° C. 
     
     
         17 . An apparatus according to  claim 14  wherein said rotatable wick has one of a circular and polygonal cross-section configurations, and at least a surface layer thereof is porous. 
     
     
         18 . An apparatus according to  claim 17  wherein successive planar surfaces of wicks with polygonal cross-sectional configurations, are provided with rounded edges. 
     
     
         19 . An apparatus according to  claim 14  including means for controlling the speed of rotation of said wick. 
     
     
         20 . An apparatus according to  claim 14  including at least two of said wicks. 
     
     
         21 . An apparatus according to  claim 14  including means for monitoring predetermined levels of molten silicon in said bath. 
     
     
         22 . An apparatus according to  claim 14  wherein said third temperature is in the range of 1500° C.-2000° C. 
     
     
         23 . An apparatus according to  claim 14  wherein said heating means in said second and third chambers comprises radiant heating means. 
     
     
         24 . An apparatus according to  claim 14  wherein including means for introducing an inert gas at a temperature in the range of 500° C. and 300° C. in the third of said chambers to cool said workpiece upon completion of said reaction. 
     
     
         25 . An apparatus according to  claim 14  including a plurality of sluice gates allowing ingress and egress of said workpieces through said chambers and the sealing of said chambers in the closed conditions thereof. 
     
     
         26 . An article made by the method comprising:
 preheating a porous carbon workpiece under an inert gas, proceeding from room temperature to a first operating temperature;   delivering liquid silicon to the porous carbon workpieces at a selected operating pressure and a second operating temperature to provide impregnation of the porous carbon workpieces with liquid silicon;   permitting reaction of the liquid silicon which has penetrated into the workpieces with carbon in the workpieces at a third temperature, resulting in the formation of silicon carbide;
 subjecting the workpieces to inert gas and cooling from the third operating temperature to a conditioning temperature with continuation of the reaction and reduction of the stresses formed in the workpieces, and 
 cooling of workpieces to room temperature, 
   wherein the delivery of silicon to the workpieces is performed by at least one porous, rotatable applicator, partially immersed in a bath of molten silicon and engageable with a workpiece, the resistance time for the delivery of molten silicon to a workpiece is determined by the speed of rotation of the applicator, and the third temperature is greater than the second temperature.   
     
     
         27 . The article according to  claim 26  wherein the second operating temperature is between 1450° C. and 1700° C. 
     
     
         28 . The article according to  claim 26  wherein in the third step the silicon molten which has been taken up by the workpiece is measured by weighing a basin containing the molten silicon before placing the workpiece and after infiltration and removal of the workpiece. 
     
     
         29 . The article according to  claim 26  wherein the silicon is transferred to the workpiece by roll wicks made in the form of prisms with polygonal cross section, and wherein their rotation takes place cyclically. 
     
     
         30 . An article made by the method comprising:
 advancing a porous workpiece along a line of travel in a chamber provided with a bath of molten silicon and an inert atmosphere, heated to a selected temperature; and   transferring molten silicon from said bath to said porous carbon workpiece as it advances along said line of travel, by means of a rotatable member having an outer layer sequentially submersible in said bath and engageable with a surface of said workpiece, formed of a material functional to absorb molten silicon upon immersion in said bath and to infuse absorbed molten silicon into said porous carbon workpiece upon contact therewith, causing said infused silicon to react with said porous carbon workpiece to form a silicon carbide workpiece.   
     
     
         31 . The article according to  claim 30  including:
 preheating said porous carbon workpiece to a temperature lower than said selected temperature, prior to admitting said workpiece to said chamber; 
 holding said silicon carbide workpiece in a chamber provided with an inert atmosphere and heated to a temperature between said selected temperature and room temperature to allow for a completion of the reaction forming silicon carbide and relieve any stress resulting therefrom; and 
 cooling said silicon carbide workpiece to room temperature. 
 
     
     
         32 . The article of  claim 30  including transferring said molten silicon with a rotatable member having a rounded workpiece engaging surface. 
     
     
         33 . The article of  claim 30  including transferring said molten silicon with a rotatable member having a polygonal cross-sectional configuration with rounded intersections of adjoining planar surfaces thereof. 
     
     
         34 . The article of  claim 30  including monitoring the amount by weight of the molten silicon transferred from said bath to said workpiece.