A graphite-zirconium carbide combined heating element and its preparation process

Abstract

The invention relates to a graphite-zirconium carbide combined heating element and its preparation process. It consists of two cold ends connected to a hot end. The hot end is made of graphite, and the cold end is sintered with zirconium carbide, graphite and sintering aids. Forming, the addition of described zirconium carbide, graphite and sintering aid is by weight percentage: zirconium carbide 50-99%, graphite 0-44%, sintering aid 1-6%; The present invention is due to the resistance of zirconium carbide composite ceramic Smaller, it is not easy to generate heat when passing a large current, so that not only the cooling device can be saved, but also the energy consumption can be significantly reduced, and at the same time, the problems of large size and easy heating caused by electrodes made of graphite materials are avoided. It overcomes the difficulty of making and processing zirconium carbide composite ceramics alone as a heating element, and can provide high temperatures above 2000 °C under vacuum conditions, or 2500 °C under reducing atmospheres.

Description

technical field [0001] The invention relates to the technical field of electric heating materials, in particular to a graphite-zirconium carbide combined heating element and a preparation process thereof. Background technique [0002] Graphite, dark gray, soft, greasy, melting point 3652°C, density 2.25g / cm 3 , resistivity 5~13×10 -6 Ω m, hardness 1.5, thermal conductivity 129 W (m K) -1 , In air or oxygen, it starts to oxidize at 450°C. As a high-temperature and ultra-high-temperature material, it is often used as a high-temperature heating element, a high-temperature heat shield, a melting electrode, and a crucible. [0003] The main features of graphite heating element: (1) Good high temperature strength, the strength of graphite is far worse than that of metal at room temperature, but with the increase of temperature, its strength gradually increases. (2) Graphite has certain characteristics of metal and ceramics, and has good thermal conductivity and electrical condu...

AI Technical Summary

Problems solved by technology

[0005] In the existing graphite heating element, the electrode material and the heating end are all graphite. In order to reduce the heating of the electrode while ensuring the heating efficiency, the method of increasing the electrode size is often adopted. However, the multiple of the electrode size increase is limited. When a large current passes through the electrode, the electrode will still generate heat. In order to reduce the electrode temperature, it is necessary to add a cooling device to cool the graphite electrode, resulting in a complex structure of the electric furnace; The heat energy mainly comes from the energy conversion generated by high current, and the energy consumption increases

Zirconium carbide composite ceramics have high hardness. When used as a heating element, it is more difficult to manufacture and process, especially making large-scale heating elements is more difficult and costly, which severely restricts its application.

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