A composite ceramic crucible for intermediate frequency furnace

Abstract

A composite ceramic crucible for intermediate frequency furnace, comprising powder materials and a dispersant accounting for 0.05-0.2 wt% of the powder materials; the powder materials include: 32-36 wt% of graphite powder; 43-46 wt% of silicon carbide; 6.5-10 wt% of electrolytic chromium powder; 6-10 wt% of magnesium oxide powder; 1-3 wt% of silicon powder; 1.5-3 wt% of aluminum dihydrogen phosphate; 0.5-1 wt% of yttrium oxide. Compared with the prior art, the composite ceramic crucible for intermediate frequency furnace provided by the present invention improves the thermal shock resistance; improves the mechanical strength; enhances the toughness; improves the oxidation resistance; prolongs the service life of the crucible; avoids the frequent aging, damage and replacement of the crucible for intermediate frequency furnace, and saves the material and labor costs.

Description

Technical Field

[0001] The present invention relates to the technical field of crucible materials for intermediate frequency induction furnaces, and particularly to a composite ceramic crucible for intermediate frequency furnaces. Background Art

[0002] Intermediate frequency induction furnaces are commonly used high-temperature smelting equipment in the iron and steel industry, non-ferrous metal industry, and precious metal industry. They have the characteristics of fast heating rate, intermittent operation, convenient operation, low pollution, and high energy efficiency. The crucible for intermediate frequency furnaces is one of the components of intermediate frequency furnace smelting and is used for metal melting, including ferrous metals, non-ferrous metals, precious metals, semiconductor materials, and rare earth metals. During the use of intermediate frequency furnace smelting, the temperature of special metal liquid reaches 1900 °C, which puts forward requirements for the crucible's thermal shock resistance, oxidation resistance, strong mechanical properties, and crack resistance at high temperatures. The service life of the crucible directly affects the production cost.

[0003] At present, the crucible materials for intermediate frequency induction furnaces are generally made of graphite silicon carbide and graphite clay. Due to the single material, it is difficult to ensure the refractoriness and oxidation resistance. The crucibles often age quickly, crack, and have a short life, increasing the cost. Summary of the Invention

[0004] In order to overcome the deficiencies in the background art, the present invention discloses a composite ceramic crucible for intermediate frequency furnaces.

[0005] To achieve the above invention purpose, the present invention adopts the following technical solutions:

[0006] A composite ceramic crucible for intermediate frequency furnaces, comprising powder materials and a dispersant accounting for 0.05 - 0.2 wt% of the powder materials; the powder materials include: 32 - 36 wt% of graphite powder; 43 - 46 wt% of silicon carbide; 6.5 - 10 wt% of electrolytic chromium powder; 6 - 10 wt% of magnesium oxide powder; 1 - 3 wt% of silicon powder; 1.5 - 3 wt% of aluminum dihydrogen phosphate; 0.5 - 1 wt% of yttrium oxide;

[0007] The preparation method of the composite ceramic crucible for intermediate frequency furnaces:

[0008] (1) Weighing and batching: Weigh and proportion the above powder materials and the dispersant;

[0009] (2) Mixing and grinding: Grind and stir the weighed ingredients in an argon atmosphere until evenly mixed;

[0010] (3) Isostatic pressing: Isostatically press the evenly mixed ingredients to obtain a blank;

[0011] (4) Primary sintering: Put the blank into an argon atmosphere for sintering, with a heating rate of 1 - 5 °C / min, rising from room temperature to 1000 °C, and keeping the temperature at 1000 °C for 2 - 4 hours;

[0012] (5) Secondary sintering: The billet after primary sintering is subjected to secondary sintering in an argon atmosphere, with a heating rate of 5 - 10 °C / min, heating from 1000 °C to 2200 °C.

[0013] (6) Cooling: The billet after secondary sintering is cooled from 2200 °C to 400 °C at a cooling rate of 0.5 - 2 °C / min, and then naturally cooled to room temperature.

[0014] Preferably, the particle size of the graphite powder is 5 - 10 μm.

[0015] Preferably, the particle size of the silicon carbide is 1 - 10 μm.

[0016] Preferably, the particle size of the electrolytic chromium powder is ≤1 μm.

[0017] Preferably, the particle size of the magnesium oxide powder is 0.5 - 5 μm.

[0018] Preferably, the particle size of the silicon powder is 1 - 5 μm.

[0019] Preferably, the particle size of the yttrium oxide is 1 - 5 μm.

[0020] Due to the adoption of the above - mentioned technical solution, the present invention has the following beneficial effects:

[0021] The crucible made by the present invention, due to the addition of metallic chromium, magnesium oxide, silicon powder, and yttrium oxide, has good thermal expansion coefficient, high temperature resistance, good oxidation resistance, impact resistance, large mechanical strength, good thermal shock resistance, and long service life, which is of great significance for reducing production costs and ensuring safety.

[0022] The present invention avoids the oxidation of metallic chromium by using argon atmosphere protection during mixing and grinding. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of the preparation method of the composite ceramic crucible for intermediate - frequency furnace. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention can be explained in detail through the following examples, and the purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. Example 1

[0025] It contains powder materials and a dispersant accounting for 0.05 wt% of the powder materials; the powder materials include: 32 wt% of graphite powder; 43.5 wt% of silicon carbide; 10 wt% of electrolytic chromium powder; 10 wt% of magnesium oxide powder; 1 wt% of silicon powder; 3 wt% of aluminum dihydrogen phosphate; 0.5 wt% of yttrium oxide;

[0026] (1)Weighing and batching: Weigh and proportionally combine the above-mentioned powder materials and dispersant;

[0027] (2)Mixing and grinding: Grind and stir the weighed ingredients in an argon atmosphere until evenly mixed;

[0028] (3)Isostatic pressing: Isostatically press the evenly mixed ingredients to obtain a blank;

[0029] (4)Primary sintering: Place the blank in an argon atmosphere for sintering, with a heating rate of 1 - 5 °C / min, raise the temperature from room temperature to 1000 °C, and keep it at 1000 °C for 4 hours;

[0030] (5)Secondary sintering: Subject the blank after primary sintering to secondary sintering in an argon atmosphere, with a heating rate of 5 - 10 °C / min, raise the temperature from 1000 °C to 2200 °C;

[0031] (6)Cooling: Cool the blank after secondary sintering at a cooling rate of 0.5 - 2 °C / min from 2200 °C to 400 °C, and then naturally cool it to room temperature to obtain the product. Example 2

[0032] It contains powder materials and a dispersant accounting for 0.1 wt% of the powder materials; the powder materials include: 34 wt% of graphite powder; 45 wt% of silicon carbide; 8 wt% of electrolytic chromium powder; 8 wt% of magnesium oxide powder; 2 wt% of silicon powder; 2.5 wt% of aluminum dihydrogen phosphate; 0.5 wt% of yttrium trioxide;

[0033] (1)Weighing and batching: Weigh and proportionally combine the above-mentioned powder materials and dispersant;

[0034] (2)Mixing and grinding: Grind and stir the weighed ingredients in an argon atmosphere until evenly mixed;

[0035] (3)Isostatic pressing: Isostatically press the evenly mixed ingredients to obtain a blank;

[0036] (4)Primary sintering: Place the blank in an argon atmosphere for sintering, with a heating rate of 1 - 5 °C / min, raise the temperature from room temperature to 1000 °C, and keep it at 1000 °C for 2 hours;

[0037] (5)Secondary sintering: Subject the blank after primary sintering to secondary sintering in an argon atmosphere, with a heating rate of 5 - 10 °C / min, raise the temperature from 1000 °C to 2200 °C;

[0038] (6)Cooling: Cool the blank after secondary sintering at a cooling rate of 0.5 - 2 °C / min from 2200 °C to 400 °C, and then naturally cool it to room temperature to obtain the product. Example 3

[0039] It contains powder materials and a dispersant accounting for 0.2 wt% of the powder materials; the powder materials include: 36 wt% of graphite powder; 46 wt% of silicon carbide; 6.5 wt% of electrolytic chromium powder; 6 wt% of magnesium oxide powder; 3 wt% of silicon powder; 1.5 wt% of aluminum dihydrogen phosphate; 1 wt% of yttrium trioxide;

[0040] (1) Weighing and batching: Weigh and proportionally combine the above-mentioned powder materials and the dispersant;

[0041] (2) Mixing and grinding: Grind and stir the weighed batching in an argon atmosphere until evenly mixed;

[0042] (3) Isostatic pressing: Isostatically press the evenly mixed batching to obtain a blank;

[0043] (4) Primary sintering: Put the blank into an argon atmosphere for sintering, with a heating rate of 1 - 5 °C / min, heat from room temperature to 1000 °C, and keep it at 1000 °C for 3 hours after reaching 1000 °C;

[0044] (5) Secondary sintering: Subject the blank after primary sintering to secondary sintering in an argon atmosphere, with a heating rate of 5 - 10 °C / min, heat from 1000 °C to 2200 °C;

[0045] (6) Cooling: Cool the blank after secondary sintering at a cooling rate of 0.5 - 2 °C / min from 2200 °C to 400 °C, and then naturally cool it to room temperature to obtain the product.

[0046] Comparative Example 1

[0047] Existing medium-frequency furnace crucible made of graphite and silicon carbide materials.

[0048] Table 1 Performance comparison table of composite ceramic crucibles for medium-frequency furnaces

[0049]

[0050] Through Figure 1 It can be seen that in the present invention, argon is used for protection during mixing and grinding, primary sintering, and secondary sintering to avoid the oxidation of metallic chromium. Combining with the test performance comparison of Examples 1 - 3 in Table 1 with the prior art (Comparative Example 1), it can be seen that compared with Comparative Example 1, Examples 1 - 3 not only have a longer service life, but also the mechanical properties exceed those of the existing medium-frequency furnace crucibles made of graphite and silicon carbide materials.

[0051] The parts not detailed in the present invention are the prior art. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and all changes falling within the meaning and scope of the equivalent elements are intended to be encompassed within the present invention.

Claims

1. A composite ceramic crucible for a medium frequency furnace, characterized in that: The invention comprises a powder and a dispersant accounting for 0.05-0.2wt% of the powder; the powder comprises: 32-36wt% of graphite powder; 43-46wt% of silicon carbide; 6.5-10wt% of electrolytic chromium powder; 6-10wt% of magnesium oxide powder; 1-3wt% of silicon powder; 1.5-3wt% of aluminum dihydrogen phosphate; and 0.5-1wt% of yttrium trioxide. The preparation method of the composite ceramic crucible for the medium frequency furnace: (1) Weighing and mixing ingredients: weigh and mix the above powder and dispersant in a certain proportion; (2) Mixing and grinding: Grind and stir the weighed ingredients under an argon atmosphere to mix them evenly; (3) Isostatic pressing: The uniformly mixed ingredients are isostatically pressed to obtain a blank; (4) Primary sintering: The blank is placed in an argon atmosphere for sintering at a heating rate of 1 to 5 °C / min from room temperature to 1000 °C, and then kept at 1000 °C for 2 to 4 hours; (5) Secondary sintering: The primary sintered blank is subjected to secondary sintering in an argon atmosphere at a heating rate of 5 to 10 °C / min from 1000 °C to 2200 °C; (6) Cooling: The secondary sintered blank is cooled from 2200°C to 400°C at a cooling rate of 0.5-2°C / min, and then naturally cooled to room temperature.

2. The composite ceramic crucible for medium frequency furnace according to claim 1, characterized in that: The graphite powder has a particle size of 5 to 10 μm.

3. The composite ceramic crucible for medium frequency furnace according to claim 1, characterized in that: The silicon carbide particle size is 1 to 10 μm.

4. The composite ceramic crucible for medium frequency furnace according to claim 1, characterized in that: The particle size of the electrolytic chromium powder is ≤1 μm.

5. The composite ceramic crucible for medium frequency furnace according to claim 1, characterized in that: The particle size of the magnesium oxide powder is 0.5 to 5 μm.

6. The composite ceramic crucible for medium frequency furnace according to claim 1, characterized in that: The particle size of the silicon powder particles is 1 to 5 μm.

7. The composite ceramic crucible for medium frequency furnace according to claim 1, characterized in that: The particle size of the yttrium oxide particles is 1 to 5 μm.

8. The composite ceramic crucible for medium frequency furnace according to claim 1, characterized in that: The invention comprises powder and a dispersant accounting for 0.05wt% of the powder; the powder comprises: 32wt% of graphite powder; 43.5wt% of silicon carbide; 10wt% of electrolytic chromium powder; 10wt% of magnesium oxide powder; 1wt% of silicon powder; 3wt% of aluminum dihydrogen phosphate; and 0.5wt% of yttrium trioxide.

9. The composite ceramic crucible for medium frequency furnace according to claim 1, characterized in that: It comprises powder and a dispersant accounting for 0.1wt% of the powder; the powder comprises: 34wt% of graphite powder; 45wt% of silicon carbide; 8wt% of electrolytic chromium powder; 8wt% of magnesium oxide powder; 2wt% of silicon powder; 2.5wt% of aluminum dihydrogen phosphate; and 0.5wt% of yttrium trioxide.

10. The composite ceramic crucible for medium frequency furnace according to claim 1, characterized in that: The invention comprises powder and a dispersant accounting for 0.2wt% of the powder; the powder comprises: 36wt% of graphite powder; 46wt% of silicon carbide; 6.5wt% of electrolytic chromium powder; 6wt% of magnesium oxide powder; 3wt% of silicon powder; 1.5wt% of aluminum dihydrogen phosphate; and 1wt% of yttrium trioxide.

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