Manufacturing line, process, and sintered article

Abstract

A manufacturing line includes a tape of green material that is directed through a furnace so that the furnace burns off organic binder material and then partially sinters the tape without the use of a setter board. Sintered articles resulting from the manufacturing line may be thin with relatively large surface areas; and, while substantially unpolished, have few sintering-induced surface defects. Tension may be applied to the partially sintered tape as it passes through a second furnace on the manufacturing line to shape resulting sintered articles.

What is claimed is: 
     
         1 . A roll of polycrystalline alumina tape that is at least partially sintered such that grains of the alumina are fused to one another, the alumina tape comprising a thickness of no more than 500 micrometers, a width at least 10 times greater than the thickness, and a length such that the width is less than 1/10th the length, wherein the length of the alumina tape is at least 1 meter. 
     
     
         2 . The roll of polycrystalline alumina tape of  claim 1 , wherein the width of the alumina tape is at least 5 millimeters, and wherein the width of the alumina tape is less than 1/20th the length of the alumina tape. 
     
     
         3 . The roll of polycrystalline alumina tape of  claim 2 , wherein the thickness of the alumina tape is at least 10 micrometers. 
     
     
         4 . The roll of polycrystalline alumina tape of  claim 2 , wherein the thickness of the alumina tape is no greater than 250 micrometers. 
     
     
         5 . The roll of polycrystalline alumina tape of  claim 4 , wherein the thickness of the alumina tape is no greater than 100 micrometers. 
     
     
         6 . The roll of polycrystalline alumina tape of  claim 5 , wherein the thickness of the alumina tape is no greater than 50 micrometers. 
     
     
         7 . The roll of polycrystalline alumina tape of  claim 4 , wherein the alumina tape has fewer than 10 pin holes of a cross-sectional area of at least a square micrometer passing through the alumina tape, per square millimeter of surface on average over a full surface of the alumina tape. 
     
     
         8 . The roll of polycrystalline alumina tape of  claim 7 , wherein the alumina tape has fewer than 1 pin hole of a cross-sectional area of at least a square micrometer passing through the alumina tape, per square millimeter of surface on average over a full surface of the alumina tape. 
     
     
         9 . The roll of polycrystalline alumina tape of  claim 7 , wherein the length of the alumina tape is at least 10 meters. 
     
     
         10 . The roll of polycrystalline alumina tape of  claim 9 , wherein the width of the alumina tape is at least 10 millimeters. 
     
     
         11 . The roll of polycrystalline alumina tape of  claim 10 , wherein the width of the alumina tape is no greater than 20 centimeters. 
     
     
         12 . The roll of polycrystalline alumina tape of  claim 10 , wherein the alumina tape has high surface quality such that first and second surfaces of the alumina tape both have at least a square centimeter of area having fewer than ten surface defects from adhesion or abrasion with a dimension greater than five micrometers, the high surface quality facilitating strength of the sintered article 
     
     
         13 . The roll of polycrystalline alumina tape of  claim 12 , wherein the alumina tape supports greater than 1 kilogram of weight without failure. 
     
     
         14 . The roll of polycrystalline alumina tape of  claim 12 , wherein the alumina tape supports about 20 megapascals of tension without failure. 
     
     
         15 . The roll of polycrystalline alumina tape of  claim 12 , wherein the width of the alumina tape is at least 50 millimeters. 
     
     
         16 . The roll of polycrystalline alumina tape of  claim 12 , wherein the alumina tape has total transmittance of at least 30% at wavelengths from about 300 nm to about 800 nm. 
     
     
         17 . The roll of polycrystalline alumina tape of  claim 16 , wherein the alumina tape has diffuse transmission through the alumina tape of at least about 10% up to about 60% at wavelengths from about 300 nm to about 800 nm. 
     
     
         18 . The roll of polycrystalline alumina tape of  claim 12 , wherein the alumina tape is translucent such that text in contact with the alumina tape may be read through the alumina tape. 
     
     
         19 . The roll of polycrystalline alumina tape of  claim 1 , further comprising a mandrel or spool, wherein the alumina tape bends around the mandrel or spool at a diameter of 1 meter or less. 
     
     
         20 . The roll of polycrystalline alumina tape of  claim 1 , further comprising a spool, wherein the alumina tape is wound on the spool. 
     
     
         21 . The roll of polycrystalline alumina tape of  claim 20 , wherein the spool has a diameter of at least 0.5 centimeters and no greater than 1 meter. 
     
     
         22 . The roll of polycrystalline alumina tape of  claim 1 , wherein the alumina tape is fully sintered and dense, having a porosity of less than 1%. 
     
     
         23 . The roll of polycrystalline alumina tape of  claim 22 , wherein the alumina tape has a porosity of less than 0.5%. 
     
     
         24 . The roll of polycrystalline alumina tape of  claim 1 , wherein the alumina tape is substantially unpolished. 
     
     
         25 . The roll of polycrystalline alumina tape of  claim 24 , wherein the alumina tape is substantially unpolished such that surfaces of the alumina tape have a granular profile. 
     
     
         26 . The roll of polycrystalline alumina tape of  claim 25 , wherein the granular profile includes grains with a height in a range from twenty-five nanometers to one-hundred-and-fifty micrometers relative to recessed portions of the surfaces at boundaries between the respective grains. 
     
     
         27 . The roll of polycrystalline alumina tape of  claim 25 , wherein the granular profile includes grains with a height in a range from twenty-five nanometers to one-hundred micrometers relative to recessed portions of the surfaces at boundaries between the respective grains. 
     
     
         28 . The roll of polycrystalline alumina tape of  claim 27 , wherein the granular profile includes grains with a height of at least fifty nanometers relative to recessed portions of the surfaces at boundaries between the respective grains. 
     
     
         29 . The roll of polycrystalline alumina tape of  claim 28 , wherein the granular profile includes grains with a height of no more than eighty micrometers relative to recessed portions of the surfaces at boundaries between the respective grains. 
     
     
         30 . The roll of polycrystalline alumina tape of  claim 24 , wherein, while being substantially unpolished, at least one surface of the alumina tape has a roughness in a range of one nanometer to ten micrometers over a distance of one centimeter in a lengthwise direction along the surface.