Claims
- 1. A method for applying a release coating to crucibles used to form molten material into a solid ingot, comprising the steps:
mixing a release coating power with a dry organic binder into a powder and binder dry mixture, mixing a defoamer with a liquid solvent into a solvent mixture, mixing said dry mixture with said solvent mixture into a wet release coating, sieving said wet release mixture so as to remove lumps and particles, wet-spraying said release mixture onto a said crucible, evaporating said solvent mixture from said wet release coating so as to leave a dry said release coating on said crucible, decomposing said binder from said dry release coating.
- 2. A method for applying a release coating according to claim 1, said crucible being a fused-silica crucible.
- 3. A method for applying a release coating according to claim 1, said molten material being silicon.
- 4. A method for applying a release coating according to claim 1, said organic binder being cellulose ether.
- 5. A method for applying a release coating according to claim 4, said cellulose ether having a viscosity of not less than 15 centipoises at 20 degrees C., at a concentration in water of two percent.
- 6. A method for applying a release coating according to claim 1, said release coating comprising a compound from among the group of compounds consisting of silicon nitride, silicon carbide, zirconium oxide, barium zirconate, magnesium zirconate.
- 7. A method for applying a release coating according to claim 1, the ratio by weight of said powder to said organic binder being at least 5:1.
- 8. A method for applying a release coating according to claim 1, said liquid solvent being deionized water with an electrical resistivity of at least 10,000 megaohms-cms.
- 9. A method for applying a release coating according to claim 1, said dry release coating having a particle size 90% by volume less than 2 microns diameter.
- 10. A method for applying a release coating according to claim 1, said defoamer comprising one of a group of defoamers consisting of polypropylene glycol and polyethylene glycol.
- 11. A method for applying a release coating according to claim 1, said wet release coating having a viscosity as measured by Zahn#2 cup of between 15 and 120 seconds, preferably between 50 and 80 seconds.
- 12. A method for applying a release coating according to claim 1, said step of decomposing comprising slowly heating said crucible in oxidizing air to at least the thermal decomposition temperature of said binder.
- 13. A method for applying a release coating according to claim 1, further comprising prior to said step of wet-spraying the step:
assuring viscosity of said wet release mixture is suitable for spray application.
- 14. A method for applying a release coating to crucibles used to form molten material into a solid ingot, comprising the steps:
weighing a unit portion of a release coating power, measuring out a corresponding portion of a dry organic binder of not more than one fifth by weight of said unit portion of release coating power, mixing said binder with said power into a dry mixture, measuring a unit volume of liquid solvent, measuring out a corresponding unit volume of a defoamer of between about 500 to 1000 parts per million by volume of said unit volume of liquid solvent, mixing said defoamer with said liquid solvent into a solvent mixture, mixing said dry mixture with said solvent mixture into a wet release coating, sieving said wet release mixture so as to remove lumps and particles, assuring viscosity of said wet release mixture is suitable for spray application, wet-spraying said release mixture onto a said crucible, evaporating said solvent mixture from said wet release coating so as to leave a dry said release coating on said crucible, separating said binder from said dry release coating by thermal decomposition.
- 15. A method for applying a release coating according to claim 14, said crucible being a fused-silica crucible, said molten material being silicon.
- 16. A method for applying a release coating according to claim 15, said release coating comprising a compound from among the group of compounds consisting of silicon nitride, silicon carbide, zirconium oxide, barium zirconate, magnesium zirconate.
- 17. A method for applying a release coating according to claim 16, said organic binder being cellulose ether having a viscosity of not less than 15 centipoises at 20 degrees C., at a concentration in water of two percent, the ratio by weight of said powder to said organic binder being at least 5:1.
- 18. A method for applying a release coating according to claim 14, said liquid solvent being deionized water with an electrical resistivity of at least 10,000 megaohms-cms, said defoamer comprising one of a group of defoamers consisting of polypropylene glycol and polyethylene glycol.
- 19. A method for applying a release coating according to claim 14, said wet release coating having a viscosity as measured by Zahn#2 cup of between 15 and 120 seconds, preferably between 50 and 80 seconds, said dry release coating having a particle size 90% by volume less than 2 microns diameter.
- 20. A method for preparing a wet release coating for spray application to crucibles used to contain molten material, comprising the steps:
weighing a unit portion of a release coating power, measuring out a corresponding portion of a dry organic binder of not more than one fifth by weight of said unit portion of release coating power, mixing said binder with said power into a dry mixture, measuring a unit volume of liquid solvent, measuring out a corresponding unit volume of a defoamer of between about 500 to 1000 parts per million by volume of said unit volume of liquid solvent, mixing said defoamer with said liquid solvent into a solvent mixture, mixing said dry mixture with said solvent mixture into a wet release coating, sieving said wet release mixture so as to remove lumps and particles, assuring viscosity of said wet release mixture is suitable for spray application.
- 21. A method for preparing a wet release coating according to claim 20, said release coating comprising a compound from among the group of compounds consisting of silicon nitride, silicon carbide, zirconium oxide, barium zirconate, magnesium zirconate.
- 22. A method for preparing a wet release coating according to claim 20, said organic binder being cellulose ether having a viscosity of not less than 15 centipoises at 20 degrees C., at a concentration in water of two percent, the ratio by weight of said powder to said organic binder being at least 5:1.
- 23. A method for preparing a wet release coating according to claim 20, said liquid solvent being deionized water with an electrical resistivity of at least 10,000 megaohms-cms.
- 24. A method for preparing a wet release coating according to claim 23, said defoamer comprising one of a group of defoamers consisting of polypropylene glycol and polyethylene glycol.
- 25. A method for preparing a wet release coating according to claim 20, said wet release coating having a viscosity as measured by Zahn#2 cup of between 15 and 120 seconds, preferably between 50 and 80 seconds, said dry release coating having a particle size 90% by volume less than 2 microns diameter.
Parent Case Info
[0001] This application relates and claims priority for all purposes to pending U.S. applications ser. No. 60/248,880 filed on Nov. 15, 2000 and serial No. 60/249,023 filed on Nov. 15, 2000
Provisional Applications (2)
|
Number |
Date |
Country |
|
60248880 |
Nov 2000 |
US |
|
60249023 |
Nov 2000 |
US |