Graphite Crucible

Introduction

 

The crucibles produced by our company are made from materials with high heat and corrosion resistance, ensuring stable performance in high-temperature environments. In addition, our crucibles have excellent thermal conductivity, which enhances melting efficiency.

We offer a wide range of technical specifications to meet diverse melting requirements. All products are manufactured under strict quality control standards, ensuring outstanding performance and consistent quality.

Our silicon carbide-graphite crucibles are produced by adding varying amounts of silicon carbide particles to the graphite crucible raw materials, such as 50%, 24%, etc. We can also customize crucibles with specific silicon carbide content to meet customers' specific requirements.

Silicon carbide-graphite crucibles are primarily used in industries such as metallurgy, casting, machinery, and chemical engineering. They are widely used for melting alloy tool steel, non-ferrous metals, and their alloys, offering superior technical and economic benefits.

Prefabrication: The crucible preforms are fabricated by fully weaving carbon fiber, with a bulk density of 0.4–0.6 g/cm³.

Curing: The crucible preforms are cured using furfural-acetone resin.

Densification: The crucible preforms are densified through repeated pitch impregnation and carbonization until their bulk density reaches 1.3–1.4 g/cm³.

Purification: After purification, the prefabricated crucibles are placed in a high-temperature furnace and trimmed to shape, forming carbon crucible billets.

Silicon Impregnation: The carbon crucible billets are immersed in a silicon impregnant for 12–24 hours under natural conditions.

Carbonization: The impregnated carbon crucible billets are placed in a carbonization furnace and carbonized at a temperature of 900–1000 °C.

Repeat Steps 5 and 6 until the density of the carbon crucible billets reaches 1.5–1.6 g/cm³.

Shaping: The inner and outer surfaces of the crucibles are ground and polished to obtain the finished silicon carbide composite crucibles.

Non-ferrous Metal Melting

This is the primary application of silicon carbide-graphite crucibles. They are ideal for melting non-ferrous metals and their alloys, including aluminum and aluminum alloys, copper and copper alloys, zinc, lead, and tin. Their excellent thermal conductivity ensures rapid and uniform heating and melting of metals, while their high corrosion resistance protects the crucibles from erosion by molten metals. These crucibles are suitable for various melting equipment, including medium-frequency induction furnaces and resistance furnaces.

Small-scale Melting of Ferrous Metals and Ferroalloys

Designed for small-scale experimental or production needs, silicon carbide-graphite crucibles are used to melt cast iron, cast steel, and ferroalloys such as ferrosilicon and ferromanganese. Compared to pure graphite crucibles, the addition of silicon carbide significantly enhances erosion resistance, allowing the crucibles to withstand the impact of molten iron and reduce the risk of cracking.

Precious Metal Refining and Casting

In refining and ingot casting processes for precious metals like gold, silver, and platinum, silicon carbide-graphite crucibles do not contaminate the molten precious metals due to their low impurity content. Their exceptional high-temperature resistance also meets the demands of melting precious metals at high temperatures. These crucibles are widely used in industries such as jewelry manufacturing and precious metal recycling.

Chemical Engineering and New Material Preparation

Silicon carbide-graphite crucibles can serve as high-temperature reaction vessels for solid-state reactions, such as the preparation of ceramic powders and new alloy materials. In laboratory or small-scale production settings, they can also be used for melting inorganic compounds to facilitate material synthesis or purification.

Situation 1: For first-time use or use after long-term storage

Step 1: Remove any moisture that may exist in the crucible.

Step 2: Heat to 200°C at a rate of 200°C/h (Purpose: Evaporate moisture and adjust for preheating).

Step 3: Hold at 200°C for 30 minutes, then heat to 600°C (Purpose: Raise temperature).

Step 4: Hold at 600°C for 30 minutes, then heat to 915°C (Purpose: Adjust the oxidation resistance of materials).

Step 5: Hold at 915°C for 60 minutes, then raise to the working temperature.

Situation 2: After a short pause (≤2 hours)

Step 1: Heat to 600°C at a rate of 200°C/h (Purpose: Melt the coating on the crucible surface).

Step 2: Hold at 600°C for 30 minutes, then heat to 915°C (Purpose: Raise temperature).

Step 3: Hold at 915°C for 60 minutes, then adjust to the working temperature (Purpose: Adjust the oxidation resistance of materials).

Maintenance

1.Store the crucible in a warm and dry area.

2.Do not nest crucibles together.

3.Do not drag the crucible directly.

4.Seal with fire clay, leaving expansion gaps on both sides of the crucible.

5.Use positioning bricks in the furnace to accommodate the crucible's thermal expansion.

6.Heat with the flame perpendicular to the crucible, surrounding it evenly.

7.Only add reagents after the metal has melted.

8.Ensure the vent holes are sealed before use to prevent crucible failure due to over-oxidation.

9.When removing the crucible, clamp the tongs 1/3 of the way up from the bottom, applying even force on both sides.

10.Carefully inspect for cracks or other damage from transportation before use.

11.The crucible base should be flat and slightly larger than the crucible bottom; installation must be centered.

12.Use a long-handled scoop to add materials gently-do not drop materials directly into the crucible.

13.Empty the crucible completely before removing it from the furnace; never let molten metal solidify inside.

14.Clean the crucible thoroughly while it is still hot daily.

15.First add some small pieces of material, then reinsert the material basket into the crucible.

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