Extrude Graphite Rod
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Extrude Graphite Rod

Extruded graphite rods are graphite materials formed by injecting graphite raw materials into an extruder through a die. The obtained extruded graphite rods have coarser particles, and although their strength is not as good as that of isostatically pressed graphite, their thermal conductivity is higher.
Isotropic in plane, suitable for large-format production. They are chemically resistant, ensuring longevity and reliability in corrosive environments.

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Product Introduction

Isotropic in plane, suitable for large-format production. They are chemically resistant, ensuring longevity and reliability in corrosive environments.

Application

Extruded graphite rod are mainly used in various vacuum resistance furnaces, induction furnaces, sintering furnaces, brazing furnaces, ion nitriding furnaces, tantalum and niobium smelting furnaces, vacuum quenching furnaces and other special graphite disks, graphite boats, graphite tubular heating elements, conductive Rods, graphite hearth plates, graphite bolts, nuts, graphite brackets, graphite molds

Molding Process

1. Extrusion molding

basic definition

Extrusion molding is to continuously squeeze the pressed powder out of the die mouth and then cut it according to the required length of the product. The length of the product is not limited by the extrusion working stroke, and the quality of the extruded product is relatively uniform along the length direction. Therefore, it is suitable for producing relatively large strip-shaped, rod-shaped, and tube-shaped products. Therefore, graphite rods are generally formed by extrusion.

If products with a large aspect ratio are molded, there will be greater difficulties in their production due to the limitations of the working stroke of the vertical molding machine and the uneven density of the product along the height direction.

Extruded carbon/graphite rods have low volume density and mechanical strength, and are anisotropic. The density of the compact does not change much in the length direction, mainly in the cross section. The density increases with the increase of the radius from the center. The center density is the smallest, the density on the same radius layer is the same, and the edge is the largest.

During the extrusion process of the compact, the pressed powder is in contact with the wall of the container, which will cause greater friction, resulting in a gradient in the friction force and flow rate, resulting in a product that is sparse inside and dense outside. In severe cases, the compact will crack or become obvious. The phenomenon of concentric shells. It will bring extremely adverse effects to the subsequent roasting process.

Extruded material compact structure

During extrusion molding, the distribution of particles when the pressed powder is pre-pressed in the material chamber is the same as that in molding. However, during extrusion, the pressed powder is extruded through the mouth, and when the pressed powder is moving, the long axis direction of the particles is consistent with the direction of movement (the movement resistance is minimal at this time). When the particles move from the material chamber to the mouth shape, as the mouth shape curve changes, the particles rotate so that the long axis direction is consistent with the direction of movement. The mouth-shaped mouth has a section of equal diameter, and the pressed powder particles pass through the equal-diameter section so that the long axis direction of the particles is parallel to the center line of the mouth-shaped mouth. The forces and distribution of particles on the same circle are the same, so the particles are distributed in concentric circles, and the layer distribution is parallel to the direction of the molding pressure.

Volume density distribution of extruded material compacts

The extrusion compact has the same density distribution on the equal diameter surface, and the density increases as the diameter increases. In the axial direction, the density change of the compact decreases from top to bottom along the compact height, but the decrease is smaller.