Heat treated ceramic substrate having ceramic coating

Abstract

A heat treated ceramic article includes a ceramic substrate and a ceramic coating on the ceramic substrate. The ceramic coating is a non-sintered ceramic coating that has a different composition than the ceramic substrate. The heat treated ceramic article further includes a transition layer between the ceramic substrate and the ceramic coating, the transition layer comprising first elements from the ceramic coating that have reacted with second elements from the ceramic substrate, wherein the transition layer has a thickness of about 0.1 microns to about 5 microns.

What is claimed is: 
     
         1 . A ceramic article comprising a ceramic substrate and a ceramic coating on the ceramic substrate, the ceramic article having been prepared by a process comprising:
 performing a thermal spraying process to form the ceramic coating on the ceramic substrate, the ceramic coating having an initial porosity and an initial amount of cracking;   heating the ceramic article to a temperature range between about 1000° C. and about 1800° C.;   performing heat treatment of the ceramic article at one or more temperatures within the temperature range for a duration to reduce a porosity of the ceramic coating to below the initial porosity and to reduce an amount of cracking of the ceramic coating to below the initial amount of cracking, wherein the ceramic article is heat treated at below a sintering temperature for the ceramic coating to prevent sintering of the ceramic coating; and   cooling the ceramic article after the heat treatment, wherein after the heat treatment the ceramic coating is not sintered, has a reduced amount of cracking that is below the initial amount of cracking, and has a reduced porosity that is below the initial porosity.   
     
     
         2 . The ceramic article of  claim 1 , wherein the ceramic coating additionally has an initial particle count and an initial adhesion strength, and wherein after the heat treatment the ceramic coating has a reduced particle count and an increased adhesion strength of about 12 Mega Pascals. 
     
     
         3 . The ceramic article of  claim 1 , wherein the ceramic substrate consists essentially of at least one of Al 2 O 3 , Quartz, SiC, Si 3 N 4 , AlN or SiC—Si 3 N 4 , wherein the ceramic substrate has a different composition than the ceramic coating. 
     
     
         4 . The ceramic article of  claim 1 , wherein the ceramic coating consists essentially of at least one of Y 2 O 3 , Y 4 Al 2 O 9 , Y 3 Al 5 O 12  (YAG), SiC, Si 3 N 4 , AlN or SiC—Si 3 N 4 , wherein the ceramic substrate has a different composition than the ceramic coating. 
     
     
         5 . The ceramic article of  claim 1 , wherein the ceramic article is a refurbished ceramic article that has been used in a plasma etch process, and wherein the heating, the performing of the heat treatment and the cooling have been performed after the plasma etch process to reduce an increased surface defect density caused by the plasma etch process. 
     
     
         6 . The ceramic article of  claim 1 , wherein the ceramic coating comprises a solid solution comprising Y 2 O 3  and at least one of Al 2 O 3 , SiO 2 , B 2 O 3 , Er 2 O 3 , Nd 2 O 3 , Nb 2 O 5 , CeO 2 , Sm 2 O 3  or Yb 2 O 3 . 
     
     
         7 . The ceramic article of  claim 1 , wherein the plasma etch process causes polymers to form on the ceramic article, wherein performing the heat treatment in the presence of oxygen dry cleans the ceramic article by causing the polymers to react with the oxygen to become gases, and wherein the refurbished ceramic article is substantially free of the polymers. 
     
     
         8 . The ceramic article of  claim 1 , wherein:
 the heating is performed at a ramping rate of about 0.1° C. per minute to about 20° C. per minute;   the duration of the heat treatment is of up to about 24 hours; and   the heating is performed at a rate of about 0.1-20° C. per minute.   
     
     
         9 . The ceramic article of  claim 1 , wherein the heat treatment causes a grain size of the ceramic coating to increase, and wherein the duration and the temperature range are selected so that the ceramic coating has a target grain size. 
     
     
         10 . A method comprising:
 performing a thermal spraying process to form a ceramic coating comprising at least one of a yttrium-based oxide or an erbium-based oxide on a ceramic article, wherein the ceramic coating has an initial porosity and an initial amount of cracking;   heating the ceramic coating to a temperature range between about 1000° C. and about 1800° C.;   heat treating the ceramic coating at one or more temperatures within the temperature range for a duration to reduce a porosity and an amount of cracking of the ceramic coating, wherein the ceramic coating is heat treated at below a sintering temperature for the ceramic coating to prevent sintering of the ceramic coating, and wherein the heat treating causes the ceramic coating to react with the ceramic article to form a transition layer between the ceramic article and the ceramic coating; and   cooling the ceramic coating after the heat treating, wherein after the heat treating the ceramic coating is not sintered, has a reduced amount of cracking that is below the initial amount of cracking, and has a reduced porosity that is below the initial porosity.   
     
     
         11 . The method of  claim 10 , wherein the ceramic substrate consists essentially of at least one of Al 2 O 3 , Quartz, SiC, Si 3 N 4 , AN or SiC—Si 3 N 4 , wherein the ceramic substrate has a different composition than the ceramic coating. 
     
     
         12 . The method of  claim 10 , wherein:
 the heating is performed at a ramping rate of about 0.1-20° C. per minute;   the duration of the heat treating is up to about 24 hours; and   the cooling is performed at a rate of about 0.1-20° C. per minute.   
     
     
         13 . The method of  claim 10 , wherein the ceramic coating comprises an initial particle count and an initial adhesion strength, and wherein after the heat treating the ceramic coating has a reduced particle count and an increased adhesion strength. 
     
     
         14 . The method of  claim 10 , wherein the heat treating is performed for a specified duration, and wherein the specified duration and the temperature range are selected to cause the transition layer to have a thickness of about 1 microns to about 2 microns. 
     
     
         15 . The method of  claim 10 , further comprising:
 after the ceramic article has been used in a plasma etch process, repeating the heating, the heat treating and the cooling to reduce an increased surface defect density caused by the plasma etch process.   
     
     
         16 . The method of  claim 15 , wherein the plasma etch process causes polymers to form on the ceramic article, and wherein repeating the heat treating in the presence of oxygen dry cleans the ceramic article by causing said polymers to react with the oxygen to become gases. 
     
     
         17 . The method of  claim 10 , wherein the heat treating causes a grain size of the ceramic coating to increase, and wherein a duration of the heat treating and the temperature range are selected so that a target grain size is reached. 
     
     
         18 . The method of  claim 10 , wherein the ceramic coating comprises a solid solution comprising Y 2 O 3  and at least one of Al 2 O 3 , SiO 2 , B 2 O 3 , Er 2 O 3 , Nd 2 O 3 , Nb 2 O 5 , CeO 2 , Sm 2 O 3  or Yb 2 O 3 . 
     
     
         19 . The method of  claim 10 , wherein:
 the heat treating is performed using at least one of laser surface treatment, electron beam surface treatment, flame surface treatment, or plasma treatment; and   the thermal spraying process is a plasma spraying process.   
     
     
         20 . A method comprising:
 receiving a heat treated ceramic article comprising a ceramic substrate and a ceramic coating that has been used in a plasma etch process, wherein the ceramic coating has an initial surface defect density caused by the plasma etch process;   heating the ceramic article to a temperature range between about 1000° C. and about 1800° C. at a ramping rate of about 0.1° C. per minute to about 20° C. per minute;   heat treating the ceramic article at one or more temperatures within the temperature range for a duration of up to about 24 hours to reduce the surface defect density caused by the plasma etch process; and   cooling the ceramic article at the ramping rate after the heat treating, wherein after completing the heat treating the heat treated ceramic article has a new surface defect density level below the surface defect density level caused by the plasma etch process.