Graphite crucibles, also known as melting copper crucibles, melting copper, etc., refer to a type of crucible made from graphite, clay, silica, and wax as raw materials. Graphite crucibles are mainly used to smelt non-ferrous metals such as copper, brass, gold, silver, zinc and lead and their alloys.
The graphite crucible is made of graphite as the main raw material and is made of plastic fire-resistant clay or carbon binder. It has the characteristics of high temperature resistance, high thermal conductivity, good corrosion resistance, long service life and so on. In the process of high temperature use, the coefficient of thermal expansion is small, and it has certain anti-strain properties for quenching and rapid heating. It has strong corrosion resistance to acidic and alkaline solutions, has excellent chemical stability, and does not participate in any chemical reactions during the smelting process. The inner wall of the graphite crucible is smooth, and the melted metal liquid is not easy to leak or adhere to the inner wall of the crucible, so that the metal liquid has good fluidity and castability, and is suitable for casting of various molds. Due to its superior properties, graphite crucibles are widely used in the smelting of alloy tool steels and the smelting of non-ferrous metals and their alloys.
The manufacturing process of graphite crucible can be divided into three types: hand-molding, spin-molding and compression-molding. The quality of graphite crucible has an important relationship with the process forming method. The forming method determines the structure, density, porosity, and mechanical strength of the blank body.
Hand-molded special-shaped crucibles for special purposes which can not be used in the case of rotary plastic and compression molding methods. Some special shaped graphite crucibles can be formed by combination of spin-molding and hand-molding.
Rotary molding is the rotation mold machine to drive the mold operation, use the inner knife to squeeze the mud to complete the mold.
Compression molding is the application of hydraulic pressure, hydraulic pressure, or pressure equipment such as kinetic energy, with steel mold for crucibles molding. Compared with the rotary plastic molding method, it has the advantages of simple process, short production cycle, high yield and efficiency, low labor intensity, less molding water, low shrinkage, low porosity, high product quality and high density.
Graphite crucibles should be protected against moisture. The graphite crucible is most afraid of moisture, and it has a great influence on the quality after being exposed to moisture. If a damp crucible is used, cracks, explosions, fall-offs and bottom-outs will occur, resulting in the loss of molten metal and even industrial accidents. Therefore, graphite crucibles must be protected from moisture during storage and use.
The storeroom where the graphite crucible is stored should be dry and ventilated, and the temperature should be kept between 5°C~25°C and the relative humidity should be 50~60%. Do not store the crucible on brick or concrete floor to avoid moisture. The bulk graphite crucible should be placed on a wooden frame, preferably 25 to 30 cm from the ground, and packed in wooden boxes, wicker baskets, or straw bags, and bedding should be placed below the cargo bed, no less than 20 cm above the ground. Placing a layer of linoleum on the sleeper is more conducive to moisture.