Surface modification process of quartz glass crucible

Abstract

A process for modifying the surface of a quartz glass crucible and a modified quartz glass crucible produced by the process, where the crucible has a transparent coated layer containing a crystallization accelerator on the surface. The process includes coating a mixed solution containing a metal salt and a partial hydrolyzate of alkoxysilane oligomer on the surface of the crucible and heating to obtain a quartz glass crucible having a transparent coated layer. The crystallization accelerator contains a metal oxide or a metal carbonate dispersed in a silica matrix.

What is claimed is:  
     
         1 . A process for modifying a surface of a quartz glass crucible, said process comprising, 
 coating a silica sol liquid comprising a metal salt and a partial hydrolyzate of an alkoxysilane oligomer on said surface of said crucible, and    heating said crucible coated with said silica sol liquid to form a transparent coated layer comprising a crystallization accelerator derived from said metal salt.    
     
     
         2 . The process of  claim 1 , wherein the metal salt is a metal organic acid salt or a metal carbonate-of one or more of magnesium, calcium, strontium, or barium.  
     
     
         3 . The process of  claim 1 , wherein the silica sol liquid is coated on a part of an inside and/or outside surface of the quartz glass crucible.  
     
     
         4 . The process of  claim 1 , wherein the silica sol liquid comprises 0.01 to 15 weight % of metal content, based on an oxide, and 0.5 to 30 weight % of silicon concentration, based on SiO 2 .  
     
     
         5 . The process of  claim 1 , further comprising, 
 drying the coated silica sol liquid, and    heating said dried silica sol liquid at a temperature of from 350 to 1200° C., for 10 to 120 minutes.    
     
     
         6 . The process of  claim 1 , wherein the metal organic salt is a carboxylate of formula C n H 2n+ COO, where n is an integer of from 3 to 7.  
     
     
         7 . The process of  claim 6 , wherein the metal organic salt is selected from the group consisting of n-butyric acid, α-methyl butyric acid, iso-valerie acid, 2-ethyl butyric acid, 2,2-dimethyl butyric acid, 3,3-dimethyl butyric acid, 2,3-dimethyl butyric acid, 3-methyl pentanoic-acid, 4-methyl pentanoic acid, 2-ethyl pentanoic acid, 3-ethyl pentanoic acid, 2,2-dimethyl pentanoic acid, 3,3-dimethyl pentanoic acid, 2,3-dimethyl pentanoic acid, 2-ethyl hexanoic acid, and 3-ethyl hexanoic acid.  
     
     
         8 . The process of  claim 1 , wherein the silica sol liquid further comprises a β-diketone.  
     
     
         9 . The process of  claim 1 , wherein the silica sol liquid further comprises an organic solvent selected from the group consisting of an ester, an alcohol, a ketone and a hydrocarbon.  
     
     
         10 . The process of  claim 1 , wherein the partial hydrolyzate of an alkoxysilane oligomer is obtained by hydrolyzing one or more silane compounds having at least one alkoxy group.  
     
     
         11 . The process of  claim 10 , wherein the alkoxysilane oligomer is selected from the group consisting of tetraethoxysilane, tetrapropoxysilane, methyltriethoxysilane, dimethylmethoxysilane, phenyltriethoxysilane, chlorotrimethylsilane, vinyltriethoxysilane, and aminopropyltriethoxysilane.  
     
     
         12 . The process of  claim 1 , wherein the silica sol liquid comprises from 0.5 to 10 wt. % of metal content based on an oxide.  
     
     
         13 . The process of  claim 1 , wherein the crucible coated with the silica sol liquid is heated at a temperature of from 600 to 1,000° C., for 10-120 minutes.  
     
     
         14 . A quartz glass crucible, comprising a transparent coated layer, wherein said coated layer comprises a crystallization accelerator dispersed in a silica matrix on at least a portion of an inside and/or an outside surface of said crucible.  
     
     
         15 . The quartz glass crucible according to  claim 14 , wherein said crucible is obtained by coating a silica sol liquid comprising a metal salt and a partial hydrolyzate of an alkoxysilane oligomer on the surface of the crucible, and heating the crucible coated with silica sol liquid to form a transparent coated layer comprising a crystallization accelerator derived from said metal salt.  
     
     
         16 . The quartz glass crucible according to  claim 14 , obtained by coating the crucible with a silica sol liquid comprising a metal organic acid salt or a metal carbonate of one or more of magnesium, calcium, strontium, or barium, on the surface of the crucible, and heating said coated silica sol liquid to form a transparent coated layer comprising the metal oxide or the metal carbonate as a crystallization accelerator.  
     
     
         17 . The quartz glass crucible according to  claim 14  wherein the crucible is used for pulling up silicon single crystal.