A coating application for reducing the potential of refractory materials to wear and failure

Abstract

The present invention discloses a coating method for applying at least one protective layer containing nitride and / or nitride derivative composites onto a refractory base material. The coating method comprises the steps of obtaining a refractory base material; preparing a slurry containing nitride and / or nitride derivative composites; applying the slurry onto at least one surface of the refractory base material; subjecting the refractory base material, with at least one surface thereof having the slurry applied, to a drying process; following the drying process, performing an annealing process at a temperature in the range of 900- 1100°C for a first predetermined period to obtain a refractory material with at least one surface coated.

Description

[0001] A COATING APPLICATION FOR REDUCING THE POTENTIAL OF REFRACTORY MATERIALS TO WEAR AND FAILURE

[0002] Technical Field

[0003] The present invention relates to applying a coating to refractory materials for increasing the wear resistance of refractory materials used in glass furnaces.

[0004] Background of the Invention

[0005] While producing glass materials, various chemicals are heated to relatively high temperatures within a glass melting furnace. During such a heating process, the materials for forming the glass undergo some physical and / or chemical changes. Therefore, refractory materials that are highly resistant to both high temperatures and the corrosive chemicals formed during chemical reactions are used in these glass furnaces.

[0006] According to the prior art, refractory materials comprise oxides such as aluminum oxide (AI2O3 - alumina), zirconium oxide (ZrO2 - zirconia), and silicon dioxide (SiO2 - silica). Structures containing these three oxides together are generally referred to as AZS (alumina-zirconia-silica).

[0007] Since AZS refractory materials have relatively high resistance to heat and chemical corrosion, they are preferred for use in glass furnaces. However, when AZS refractory materials are used in their raw state, they wear down over time due to the effects of abrasive chemicals and heat. Additionally, over time, the glassy phase within the AZS refractory material migrates to the outside of the refractory material. Therefore, the prior art includes a coating process applied to said AZS refractory materials using reinforcing materials to enhance durability.

[0008] CN103693979A, which is included in the known-state of the art, discloses coating a refractory material containing zirconia with a material containing boron nitride. According to this document, initially, a refractory brick containing zirconia is obtained, which is then immersed and allowed to soak in a mixture containing boron nitride. The refractory brick is removed from the mixture and dried. This process results in a coating structure containing boron nitride of a specific thickness on the refractory material. Although the durability of the refractory material is enhanced by the coating according to this document, the durability of the resulting coated material is not sufficiently high. Therefore, there is a need for a coating method, especially to further enhance the durability of AZS refractory materials.

[0009] Brief Description of the Invention

[0010] The present invention discloses a coating method for applying at least one protective layer containing nitride and / or nitride derivative composites onto a refractory base material. The coating method comprises the steps of obtaining a refractory base material; preparing a slurry containing nitride and / or nitride derivative composites; applying the slurry onto at least one surface of the refractory base material; subjecting the refractory base material, with at least one surface thereof having the slurry applied, to a drying process; following the drying process, performing an annealing process at a temperature in the range of 900- 1100°C for a first predetermined period to obtain a refractory material with at least one surface coated.

[0011] In the coating method according to the present invention, a slurry containing nitride and / or nitride derivative composites is applied onto a refractory material and subjected to annealing, allowing at least a portion of the coating to penetrate into the surface of the refractory material. This ensures a strong bond between the refractory base material and the coating, thereby enhancing the wear resistance of the refractory material.

[0012] Object of the Invention

[0013] An object of the present invention is to provide a coating method for increasing the wear resistance of refractory materials especially used in glass furnaces.

[0014] Another object of the present invention is to provide a coating method in which the coating material is allowed to penetrate into the refractory material. Yet another object of the present invention is to provide a coated refractory material coated with said coating method.

[0015] Description of the Invention

[0016] In glass furnaces, where heating processes involve high temperatures and various chemicals, it is necessary to use materials on the inner surface of the furnace that are resistant to heat and wear. Therefore, refractory materials containing substances such as aluminum oxide (AI2O3 - alumina), zirconium oxide (ZrO2 - zirconia), and silicon dioxide (SiO2 - silica) are commonly used in glass furnaces. Coating processes are applied to these refractory materials to enhance their durability. Therefore, the present invention provides a coating method for increasing the wear resistance of refractory materials.

[0017] The coating method according to the present invention enables the application of at least one protective layer containing nitride and / or nitride derivative composites onto a refractory base material, the coating method comprising the steps of obtaining a refractory base material, preferably containing alumina, zirconia, and silica; preparing a slurry containing nitride and / or nitride derivative composites; applying the slurry onto at least one surface of the refractory base material; subjecting the refractory base material, with at least one surface thereof having the slurry applied, to a drying process; following the drying process, performing an annealing process, preferably under atmospheric conditions, at a temperature in the range of 900-1100°C (preferably 1000°C) for a first predetermined period (for example, a period ranging from 30 to 60 minutes) to obtain a refractory material with at least one surface coated. Here, nitride and / or nitride derivative composite may comprise nitride (such as BN, AIN, etc.) or carbide (such as B4C, ZrC, SiC, etc.) alone, or may comprise oxide / carbide-doped nitride composite compounds (such as BN-AI2O3, BN-AI2O3-SiO2, BN-ZrO2, BN-SiC, AIN-AI2O3, etc.).

[0018] In an exemplary embodiment of the invention, a slurry containing boron nitride is applied to at least one surface of the AZS refractory base material, e.g. in brick form, and the slurry is allowed to dry on the applied surface. After drying, a high-temperature annealing process is conducted. This annealing process at high temperatures ensures that the boron nitride-containing slurry penetrates into the surface of the refractory base material where it was applied. Studies have revealed that after the annealing process, the boron nitride-containing slurry penetrates to a depth of more than 300 pm into the surface. Here, due to the penetration of the boron nitride-containing slurry into said surface, not just remaining on the surface, the migration of the glassy phase within the AZS refractory material out of the refractory material itself is prevented, especially at high temperatures. Additionally, a pure coating material of 50-100 pm thickness was observed on the surface where the slurry was applied. This pure coating prevents the wear of the coated refractory material due to high temperatures and / or chemicals, thereby extending the service life of the refractory material.

[0019] In a preferred embodiment of the invention, the step of preparing a slurry containing nitride and / or nitride derivative composites comprises mixing powdered boron nitride with at least one liquid and at least one inorganic / organic binder. Said liquid comprises water and / or ethanol. Said binders comprise inorganic or organic compounds such as sodium polyacrylate, ammonium polyacrylate, sodium silicate, potassium silicate, or mixtures thereof. The ratio of the binder to boron nitride is preferably in the range of 5-10% by weight. Boron nitride may be used directly in powder form, or the step of preparing a slurry containing boron nitride may also comprise grinding boron nitride into powder form using a grinder.

[0020] In an alternative embodiment of the invention, the step of preparing a slurry containing nitride and / or nitride derivative composites comprises mixing the powdered boron nitride with alumina powder and / or silica powder, at least one liquid and at least one binder. Said liquid comprises water and / or ethanol. Said binder may comprise inorganic or organic compounds such as sodium polyacrylate, ammonium polyacrylate, sodium silicate, potassium silicate, or mixtures thereof. The ratio of the binder to the powders (boron nitride powder, alumina powder, and / or silica powder total) is preferably in the range of 5- 10% by weight. In this embodiment, boron nitride and alumina powder and / or silica powder are subjected to a mechanical alloying process. In other words, the step of preparing a slurry containing boron nitride comprises grinding and mixing boron nitride with alumina and / or silica in a grinder to form a composite. The grinding / mixing process is preferably carried out in a high-energy ball mill at 1200 revolutions per minute for more than 1 hour. In a preferred embodiment, boron nitride is used at a ratio of 80% by weight and alumina at a ratio of 20% by weight. In a preferred embodiment of the invention, the step of applying the slurry onto at least one surface of the refractory base material comprises the step of dip coating, in which the refractory base material is immersed into the slurry containing nitride and / or nitride derivative composites. In alternative embodiments, the step of applying the slurry onto at least one surface of the refractory base material comprises the steps of brush coating or thermal spraying, instead of dip coating.

[0021] In a preferred embodiment of the invention, the step of subjecting the refractory base material, with at least one surface thereof having the slurry applied, to a drying process comprises the step of drying in an oven (for example, for 1 hour) or drying at room temperature (for example, for 24 hours).

[0022] In a preferred embodiment of the invention, the coating method comprises repeating the steps of applying the slurry onto at least one surface of the refractory base material and of subjecting the refractory base material, with at least one surface thereof having the slurry applied, to a drying process, at least once. The number of repetitions may vary depending on the characteristics of the slurry used and the method of application to the refractory base material (e.g. dip coating, brush coating, or thermal spraying). Here, the process involves repeating each immersion with a subsequent drying step (re-immersion after drying), ensuring a more homogeneous application of the slurry onto the surface of the refractory base material.

[0023] The present invention also provides a refractory material which is coated using any of the methods described above. The refractory material according to the present invention comprises at least one refractory base material preferably containing alumina, zirconia, and silica; and at least one coating applied to at least one surface of the refractory base material and containing nitride and / or nitride derivative composites, wherein said coating comprises a portion that penetrates into the coating surface of the refractory base material. Additionally, besides boron nitride, said coating may also comprise alumina and / or silica. The portion of the coating that penetrates into the refractory base material is preferably located at a depth greater than 300 pm beneath the surface of the refractory base material, with the thickness of the coating remaining on the surface preferably in the range of 50 to 100 pm. In the coating method according to the present invention, a slurry containing nitride and / or nitride derivative composites is applied onto a refractory material and subjected to annealing, allowing at least a portion of the coating to penetrate into the surface of the refractory material. This ensures a strong bond between the refractory base material and the coating, thereby enhancing the wear resistance of the refractory material.

Claims

CLAIMS1. A coating method for applying at least one protective layer containing nitride and / or nitride derivative composites onto a refractory base material, characterized by comprising the steps of: obtaining a refractory base material; preparing a slurry containing nitride and / or nitride derivative composites; applying the slurry onto at least one surface of the refractory base material; subjecting the refractory base material, with at least one surface thereof having the slurry applied, to a drying process; following the drying process, performing an annealing process at a temperature in the range of 900-1100°C for a first predetermined period to obtain a refractory material with at least one surface coated.

2. A coating method according to claim 1, characterized in that nitride and / or nitride derivative composite comprises nitride or carbide alone, or comprises oxide / carbide-doped nitride composite compounds.

3. A coating method according to claim 1 or 2, characterized in that the refractory base material comprises alumina, zirconia, and silica.

4. A coating method according to any of the preceding claims, characterized in that the annealing process is conducted at a temperature of 1000°C.

5. A coating method according to any of the preceding claims, characterized in that said first period is in the range of 30-60 minutes.

6. A coating method according to any of the preceding claims, characterized in that the annealing process is conducted under atmospheric conditions.

7. A coating method according to any of the preceding claims, characterized in that the step of preparing a slurry containing nitride and / or nitride derivative composites comprises mixing powdered boron nitride with at least one liquid and at least one inorganic / organic binder.

8. A coating method according to claim 7, characterized in that said liquid comprises water and / or ethanol.

9. A coating method according to claim 7 or 8, characterized in that the ratio of the binder to boron nitride is in the range of 5% to 10% by weight.

10. A coating method according to claim 7 or 8, characterized in that the step of preparing a slurry containing nitride and / or nitride derivative composites comprises grinding boron nitride into powder form using a grinder.

11. A coating method according to any of the claims 1 to 6, characterized in that the step of preparing a slurry containing nitride and / or nitride derivative composites comprises mixing the powdered boron nitride with alumina powder and / or silica powder, at least one liquid and at least one organic / inorganic binder.

12. A coating method according to claim 11 , characterized in that said liquid comprises water and / or ethanol.

13. A coating method according to claim 11 or 12, characterized in that the ratio of the binder to powders is in the range of 5% to 10% by weight.

14. A coating method according to any of the claims 11 to 13, characterized in that the step of preparing a slurry containing nitride and / or nitride derivative composites comprises grinding and mixing boron nitride with alumina and / or silica in a grinder to form a composite.

15. A coating method according to claim 14, characterized in that the grinding / mixing process is carried out in a high-energy ball mill at 1200 revolutions per minute for more than 1 hour.

16. A coating method according to any of the preceding claims, characterized in that the step of applying the slurry onto at least one surface of the refractory basematerial comprises the step of dip coating, in which the refractory base material is immersed into the slurry containing nitride and / or nitride derivative composites.

17. A coating method according to any of the claims 1 to 15, characterized in that the step of applying the slurry onto at least one surface of the refractory base material comprises the step of brush coating.

18. A coating method according to any of the claims 1 to 15, characterized in that the step of applying the slurry onto at least one surface of the refractory base material comprises the step of thermal spraying.

19. A coating method according to any of the preceding claims, characterized in that the step of subjecting the refractory base material, with at least one surface thereof having the slurry applied, to a drying process comprises the step of drying in an oven.

20. A coating method according to any of the claims 1 to 18, characterized in that the step of subjecting the refractory base material, with at least one surface thereof having the slurry applied, to a drying process comprises the step of drying at room temperature.

21. A coating method according to any of the preceding claims, characterized in that the coating method comprises repeating the steps of applying the slurry onto at least one surface of the refractory base material and of subjecting the refractory base material, with at least one surface thereof having the slurry applied, to a drying process, at least once.

22. A refractory material which is coated using a coating method according to any of the preceding claims.

23. A refractory material suitable for use in glass furnaces, characterized by comprising at least one refractory base material; and at least one coating applied to at least one surface of the refractory base material and containing nitride and / ornitride derivative composites, wherein said coating comprises a portion that penetrates into the coating surface of the refractory base material.

24. A refractory material according to claim 23, characterized in that the refractory base material comprises alumina, zirconia, and silica.

25. A refractory material according to claim 23 or 24, characterized in that said coating comprises alumina and / or silica in addition to boron nitride.