Graphite powder used as graphite electrodes does have many advantages. However, how to bring out the advantages of this material, truly achieve efficiency improvement, cost reduction and market competitiveness enhancement, these are not only issues for graphite producers to consider, but also problems that graphite users should take seriously. So, when applying graphite materials, what problems should be solved first?
Dust removal: Due to the fine particle structure of graphite, a large amount of dust is produced during mechanical processing, which has a significant impact on the factory environment. In addition, the impact of dust on equipment is mainly reflected in its influence on the power supply of the equipment. Due to the excellent electrical conductivity of graphite, once it enters the power box, it is prone to cause power short circuits and other faults. Therefore, it is recommended to be equipped with a special graphite processing machine for processing. However, due to the high investment cost of special processing equipment for graphite, many enterprises are rather cautious in this regard. Under such circumstances, the following several solutions can be adopted:
Graphite electrode outsourcing: With the increasingly widespread application of graphite in the mold industry, more and more mold contract manufacturing (OEM) enterprises have also introduced the OEM business of graphite electrodes.
After oil immersion processing: After purchasing graphite, it is first immersed in spark oil for a period of time (the specific time depends on the volume of the graphite), and then placed in a machining center for processing. In this way, the graphite dust will not fly around but fall down. This will minimize the impact on the equipment and the environment.
Modifying a machining center: The so-called modification mainly involves installing a vacuum cleaner on an ordinary machining center.
The discharge gap during the processing of discharge graphite: Unlike copper, due to the faster discharge rate of graphite electrodes, more processing slag is corroded out per unit time. How to effectively remove the slag becomes a problem. Therefore, it is required that the discharge gap be larger than that of copper. Generally speaking, when setting the discharge gap, the discharge gap of graphite is 10 to 30% larger than that of copper.
Correct understanding of its shortcomings: Besides dust, graphite also has some deficiencies. For instance, when processing mirror surface molds, compared with copper electrodes, graphite electrodes are less likely to achieve the desired effect. To achieve a better surface effect, the finest particle size of graphite should be selected, and the cost of this kind of graphite is often 4 to 6 times higher than that of ordinary graphite. In addition, the reusability of graphite is relatively low. Due to the production process, only a small portion of graphite can be used for reproduction and utilization. The waste graphite after electrical discharge machining cannot be reused for the time being, thus posing certain challenges to the environmental management of enterprises. In this regard, we can provide free recycling of waste graphite for customers to avoid causing trouble for their environmental certification.
Chipping in mechanical processing: As graphite is more brittle than copper, if graphite is processed using the same method as copper electrodes, it is easy to cause chipping of the electrodes, especially when processing thin-ribbed electrodes. In this regard, free technical support can be provided to mold manufacturers. It is mainly achieved through the selection of cutting tools, the way of tool passage, and the reasonable configuration of processing parameters. Natural flake graphite samples were formed by cold pressing without binder using natural flake graphite. The effects of changes in forming pressure and holding pressure time on the density, porosity and flexural strength of the samples were studied respectively. The relationship between the microstructure and flexural strength of natural flake graphite samples was qualitatively analyzed. Two systems, boric acid – urea and tetraethyl silicate – acetone – hydrochloric acid, were selected to study and discuss the antioxidant properties and mechanisms of natural graphite powder and natural graphite electrode samples before and after antioxidant treatment respectively. The main research contents and results are as follows: The forming performance of natural flake graphite and the influence of forming conditions on microstructure and properties were studied. The results show that the greater the forming pressure of the natural flake graphite sample, the greater the density and flexural strength of the sample, while the smaller the porosity of the sample. The holding pressure time has little effect on the density of the sample. When it is more than 5 minutes, the formability of the sample is better. The flexural strength shows obvious anisotropy, and the average flexural strengths in different directions are 5.95MPa, 9.68MPa, and 12.70MPa respectively. The anisotropy of flexural strength is closely related to the microstructure of graphite.
The antioxidant properties of the boron-nitrogen system prepared by solution method and sol method and the natural flake graphite powder coated with silica sol before and after were studied. The results show that as the number of impregnations increases, the amount of silica sol and boron-nitrogen system coated on the surface of graphite powder increases, and the antioxidant property becomes better. The initial oxidation temperature of natural flake graphite is 883K, and the oxidation weight loss rate at 923K is 407.6mg/g/h. The graphite powder was impregnated nine times respectively in the boric acid – urea system and the ethyl silicate – ethanol – hydrochloric acid system. After heat treatment for 1 hour under the atmosphere of 1273K and N2, the oxidation weight loss rate of natural flake graphite at 923K was 47.9 mg/g/h and 206.1mg/g/h respectively. After heat treatment for 1 hour in N2 atmospheres of 1973K and 1723K respectively, the oxidation weight loss rates of natural flake graphite at 923K were 3.0mg /g/h and 42.0mg/g/h respectively; Both systems can reduce the oxidation weight loss rate of natural flake graphite, but the antioxidant effect of the boric acid – urea system is better than that of the ethyl silicate – ethanol – hydrochloric acid system.
Graphite electrodes are mainly used in large-scale industries such as electric furnace steelmaking, phosphorus production in ore furnaces, electric melting of magnesia sand, electric melting preparation of refractory materials, aluminum electrolysis, and industrial phosphorus, silicon, and calcium carbide production. Graphite electrodes are divided into two types: natural graphite electrodes and artificial graphite electrodes. Compared with artificial graphite electrodes, natural graphite electrodes do not require a graphite chemical process. As a result, the production cycle of natural graphite electrodes is significantly reduced, energy consumption and pollution are greatly decreased, and costs are notably lowered. They have obvious price advantages and economic benefits, which is one of the main reasons for the development of natural graphite electrodes.
In addition, natural graphite electrodes are high-value-added deep-processed products of natural graphite and have significant development and application value. However, the forming performance, oxidation resistance and mechanical properties of natural graphite electrodes are currently inferior to those of artificial graphite electrodes, which is the main obstacle to their development. Therefore, overcoming these obstacles is the key to developing the application of natural graphite electrodes.
The antioxidant properties of the boron-nitrogen system prepared by solution method and sol method and the natural flake graphite blocks coated with silica sol before and after were studied. The results show that the antioxidant property of natural graphite blocks coated with silica sol becomes worse as the number of impregnations increases. The boron-nitrogen system coated natural graphite blocks have better antioxidant properties as the number of impregnations increases. The oxidation weight loss rates of natural graphite blocks at 923K and 1273K were 122.432mg/g/h and 191.214mg/g/h, respectively. The natural graphite blocks were impregnated nine times respectively in the boric acid – urea system and the ethyl silicate – ethanol – hydrochloric acid system. After heat treatment for 1 hour in the atmosphere of 1273K and N2, the oxidation weight loss rates at 923K were 20.477mg/g/h and 28.753mg/g/h, respectively. At 1273K, they were 37.064mg/g/h and 54.398mg/g/h respectively; After treatment at 1973K and 1723K respectively, the oxidation weight loss rates of natural graphite blocks at 923K were 8.182 mg/g/h and 31.347mg/g/h respectively; At 1273K, they were 126.729mg/g/h and 169.978mg/g/h respectively; Both systems can significantly reduce the oxidation weight loss rate of natural graphite blocks. Similarly, the antioxidant effect of the boric acid – urea system is superior to that of the ethyl silicate – ethanol – hydrochloric acid system.
Post time: Jun-12-2025