Plasma spraying

Abstract

Plasma spraying, apparatus for plasma spraying, and methods of plasma spraying.

1 . A method for making amorphous material, the method comprising: 
 feeding particles into a plasma to provide a melt, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, and a metal oxide other than Al 2 O 3 , wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2 ; and    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, and the metal oxide other than Al 2 O 3 , wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized.    
   
   
       2 . The method according to  claim 1  wherein spraying and cooling the melt includes spraying the melt onto a substrate and cooling to provide the amorphous material.  
   
   
       3 . The method according to  claim 1  wherein spraying and cooling the melt includes spraying the melt into a liquid to cool the melt and provide particles comprising the amorphous material.  
   
   
       4 . The method according to  claim 1  wherein the particles each comprise at least 35 percent by weight Al 2 O 3 , based on the total weight of the particle, and wherein the amorphous material comprises at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material.  
   
   
       5 . The method according to  claim 1  wherein spraying and cooling the melt provides ceramic comprising the amorphous material.  
   
   
       6 . A method for making amorphous material, the method comprising: 
 feeding particles into a plasma to provide a melt, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, a first metal oxide other than Al 2 O 3 , and a second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 80 percent by weight of the particles, and wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the first or second metal oxide is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms a distinct crystalline phase when the amorphous material is crystallized; and    spraying and cooling the melt to provide the amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, the first metal oxide other than Al 2 O 3 , and the second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 80 percent by weight of the amorphous material, wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers, with the proviso that if the first or second metal oxide is ZrO 2 , then the amorphous material further comprises a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized.    
   
   
       7 . A method for making amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis;    delivering particles into the plasma gas jet through at least a first carrier conduit to provide a melt, the first carrier conduit comprising a conduit axis that intersects the jet axis at an angle of not greater than 75 degrees, wherein the first conduit extends away from the jet axis in the delivery direction, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, and a metal oxide other than Al 2 O 3 , wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2 ; and    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, and the metal oxide other than Al 2 O 3 , wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized.    
   
   
       8 . A method for making amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis;    delivering particles into the plasma gas jet through at least a first carrier conduit to provide a melt, the first carrier conduit comprising a conduit axis that intersects the jet axis at an angle of not greater than 75 degrees, wherein the first conduit extends away from the jet axis in the delivery direction, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, a first metal oxide other than Al 2 O 3 , and a second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 80 percent by weight of the particles, and wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the first or second metal oxide is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms a distinct crystalline phase when the amorphous material is crystallized; and    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, the first metal oxide other than Al 2 O 3 , and the second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 80 percent by weight of the amorphous material, wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material.    
   
   
       9 . A method for making amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis;    delivering particles into the plasma gas jet through at least a first carrier conduit to provide a melt, the first carrier conduit comprising a particle delivery vector that intersects the jet axis at an angle of not greater than 75 degrees, and further wherein the particle delivery vector comprises a vector component having a direction that is substantially opposite the delivery direction, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, and a metal oxide other than Al 2 O 3 , wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2 ; and    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, and the metal oxide other than Al 2 O 3 , wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized.    
   
   
       10 . A method for making amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis;    delivering particles into the plasma gas jet through at least a first carrier conduit to provide a melt, the first carrier conduit comprising a particle delivery vector that intersects the jet axis at an angle of not greater than 75 degrees, and further wherein the particle delivery vector comprises a vector component having a direction that is substantially opposite the delivery direction, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, a first metal oxide other than Al 2 O 3 , and a second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 80 percent by weight of the particles, and wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the first or second metal oxide is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms a distinct crystalline phase when the amorphous material is crystallized; and    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, the first metal oxide other than Al 2 O 3 , and the second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 80 percent by weight of the amorphous material, wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material.    
   
   
       11 . A method for making amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis that extends along the delivery direction;    delivering particles entrained in a carrier gas into the plasma gas jet to provide a melt, the carrier gas comprising at least 50 percent by volume nitrogen, based on the total weight of the carrier gas, and the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, and a metal oxide other than Al 2 O 3 , wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2 ; and    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, and the metal oxide other than Al 2 O 3 , wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized.    
   
   
       12 . A method for making amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis that extends along the delivery direction;    delivering particles entrained in a carrier gas into the plasma gas jet to provide a melt, the carrier gas comprising at least 50 percent by volume nitrogen, based on the total weight of the carrier gas, and the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, a first metal oxide other than Al 2 O 3 , and a second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 80 percent by weight of the particles, and wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2   0   3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the first or second metal oxide is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms a distinct crystalline phase when the amorphous material is crystallized; and    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, the first metal oxide other than Al 2 O 3 , and the second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 80 percent by weight of the amorphous material, wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material.    
   
   
       13 . A method for making glass-ceramic from amorphous material, the method comprising: 
 feeding particles into a plasma to provide a melt, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, and a metal oxide other than Al 2 O 3 , wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized;    spraying and cooling the melt to provide the amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, and the metal oxide other than Al 2 O 3 , wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the amorphous material further comprises a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized; and    heat-treating the amorphous material such that at least a portion of the amorphous material is converted to a glass-ceramic.    
   
   
       14 . A method for making glass-ceramic from amorphous material, the method comprising: 
 feeding particles into a plasma to provide a melt, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, a first metal oxide other than Al 2 O 3 , and a second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 70 percent by weight of the particles, and wherein the particles contain not more than 30 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles;    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, the first metal oxide other than Al 2 O 3 , and the second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 70 percent by weight of the amorphous material, wherein the amorphous material contains not more than 30 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers, with the proviso that if the first or second metal oxide is ZrO 2 , then the amorphous material further comprises a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized; and    heat-treating the amorphous material such that at least a portion of the amorphous material is converted to a glass-ceramic.    
   
   
       15 . A method for making glass-ceramic from amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis;    delivering particles into the plasma gas jet through at least a first carrier conduit to provide a melt, the first carrier conduit comprising a conduit axis that intersects the jet axis at an angle of not greater than 75 degrees, wherein the first conduit extends away from the jet axis in the delivery direction, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, and a metal oxide other than Al 2 O 3 , wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized;    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, and the metal oxide other than Al 2 O 3 , wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the amorphous material further comprises a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized; and    heat-treating the amorphous material such that at least a portion of the amorphous material is converted to a glass-ceramic.    
   
   
       16 . A method for making glass-ceramic from amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis;    delivering particles into the plasma gas jet through at least a first carrier conduit to provide a melt, the first carrier conduit comprising a conduit axis that intersects the jet axis at an angle of not greater than 75 degrees, wherein the first conduit extends away from the jet axis in the delivery direction, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, a first metal oxide other than Al 2 O 3 , and a second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 70 percent by weight of the particles, and wherein the particles contain not more than 30 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles;    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, the first metal oxide other than Al 2 O 3 , and the second, different metal oxide other than Al  2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 70 percent by weight of the amorphous material, wherein the amorphous material contains not more than 30 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers; and    heat-treating the amorphous material such that at least a portion of the amorphous material is converted to a glass-ceramic.    
   
   
       17 . A method for making glass-ceramic from amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis;    delivering particles into the plasma gas jet through at least a first carrier conduit to provide a melt, the first carrier conduit comprising a particle delivery vector that intersects the jet axis at an angle of not greater than 75 degrees, and further wherein the particle delivery vector comprises a vector component having a direction that is substantially opposite the delivery direction, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, and a metal oxide other than Al 2 O 3 , wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized;    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, and the metal oxide other than Al 2 O 3 , wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the amorphous material further comprises a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized; and    heat-treating the amorphous material such that at least a portion of the amorphous material is converted to a glass-ceramic.    
   
   
       18 . A method for making glass-ceramic from amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis;    delivering particles into the plasma gas jet through at least a first carrier conduit to provide a melt, the first carrier conduit comprising a particle delivery vector that intersects the jet axis at an angle of not greater than 75 degrees, and further wherein the particle delivery vector comprises a vector component having a direction that is substantially opposite the delivery direction, the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, a first metal oxide other than Al 2 O 3 , and a second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 70 percent by weight of the particles, and wherein the particles contain not more than 30 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles;    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, the first metal oxide other than Al 2 O 3 , and the second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 70 percent by weight of the amorphous material, wherein the amorphous material contains not more than 30 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers; and    heat-treating the amorphous material such that at least a portion of the amorphous material is converted to a glass-ceramic.    
   
   
       19 . A method for making glass-ceramic from amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis that extends along the delivery direction;    delivering particles entrained in a carrier gas into the plasma gas jet to provide a melt, the carrier gas comprising at least 50 percent by volume nitrogen, based on the total weight of the carrier gas, and the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, and a metal oxide other than Al 2 O 3 , wherein the particles contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the particles further comprise a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized;    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, and the metal oxide other than Al 2 O 3 , wherein the amorphous material contains not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers, with the proviso that if the metal oxide other than Al 2 O 3  is ZrO 2 , then the amorphous material further comprises a metal oxide other than Al 2 O 3  and ZrO 2  at least a portion of which forms at least one distinct crystalline phase when the amorphous material is crystallized; and    heat-treating the amorphous material such that at least a portion of the amorphous material is converted to a glass-ceramic.    
   
   
       20 . A method for making glass-ceramic from amorphous material, the method comprising: 
 generating a plasma gas jet in a delivery direction, the plasma gas jet being substantially symmetrical about a jet axis that extends along the delivery direction;    delivering particles entrained in a carrier gas into the plasma gas jet to provide a melt, the carrier gas comprising at least 50 percent by volume nitrogen, based on the total weight of the carrier gas, and the particles comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the particles, a first metal oxide other than Al 2 O 3 , and a second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 70 percent by weight of the particles, and wherein the particles contain not more than 30 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the particles;    spraying and cooling the melt to provide amorphous material, the amorphous material comprising at least 35 percent by weight Al 2 O 3 , based on the total weight of the amorphous material, the first metal oxide other than Al 2 O 3 , and the second, different metal oxide other than Al 2 O 3 , wherein the Al 2 O 3 , first metal oxide, and second metal oxide collectively comprise at least 70 percent by weight of the amorphous material, wherein the amorphous material contains not more than 30 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the amorphous material, wherein the amorphous material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 25 micrometers; and    heat-treating the amorphous material such that at least a portion of the amorphous material is converted to a glass-ceramic.