Quality Monitoring of Carbon graphite – High Purity Carbon graphite

Due to its special structure, carbon graphite has many characteristics such as high temperature resistance, thermal shock resistance, electrical conductivity, lubricity, chemical stability and plasticity. It has a wide range of applications, and the quality requirements of carbon graphite must also be certain. To ensure that, the Franli factory detects impurities in the graphite by ashing method, and uses the Franli factory ventilation treatment system to bake high-purity carbon graphite. Carbon graphite also has a wonderful property: the strength of carbon graphite increases with increasing temperature, and at 2000 ° C, the strength of carbon graphite doubles.

The production process of high-purity carbon graphite

High-purity carbon graphite generally refers to carbon graphite with a carbon content greater than 99.99% and a total ash content of ≤50ppm. According to different use, it is divided into 50×10-6, 20×10-6, 10×10-6 and other levels. The production of high-purity carbon graphite in China is basically based on the purification and ventilation treatment system. Due to the loss of a large amount of electrical energy and thermal energy in the system, the thermal utilization rate is very low.

(1) Select petroleum coke or pitch coke with as low ash content as possible, and the particle size of calcined coke grinding powder needs to be particularly fine when producing fine-structure high-pure carbon graphite;

(2) Generally, cold molding or warm molding is used;

(3) need to carry out roasting cycle treatment after 2～4 times of dipping;

(4) Adopt ventilation carbon graphitization purification process, feed chlorine or freon gas at 2000～2800 ℃ high temperature, make impurity element form chloride or fluoride volatilization and escape, and send when furnace temperature is down to 1800 ℃ Pure nitrogen gas is introduced to discharge excess chlorine gas or fluorine gas to achieve the purpose of purification.

Detection of impurities in high-purity carbon graphite

For the analysis of trace impurities in high-purity carbon graphite, the sample is usually pre-ashed or wet-digested to remove carbon, and the ash is dissolved with acid, and then the impurity content in the solution is determined. The ashing method does not require the use of ultra-pure acids to dissolve the ash, thus avoiding the danger of introducing the element to be measured, so it is used more. The detection of high-purity carbon graphite ash is also very difficult, because the enrichment of ash requires high-temperature burning, and at high temperature, the ash will stick to the sample boat and be difficult to separate, which makes it impossible to accurately determine the composition and content of impurities.

Existing methods all take advantage of the property of platinum crucibles that do not react with acid, use platinum crucibles to burn high-purity carbon graphite to enrich ash, and then directly heat the samples in the crucibles to dissolve the samples, and the components in the solution can be calculated by measuring the composition. Impurity content in carbon graphite. However, this method has certain limitations, because high-purity carbon graphite contains a large amount of carbon, which can make the platinum crucible brittle and fragile under high temperature conditions, which is easy to cause the platinum crucible to rupture, and the detection cost is very high, which is difficult to be widely used. Since conventional methods cannot detect the impurity components of high-purity carbon graphite, it is necessary to improve the detection method.

Influence of carbon graphite purification at high temperature

1.The impurity content of carbon graphite raw materials. The higher the impurity of the raw material, the higher the quality content of the obtained product. The purity requirement of the raw material purified by the high temperature method is generally above 99%.

2.The pros and cons of the quality of carbon graphite crucibles. The ash content of carbon graphite is higher than the ash content of carbon graphite crucible, which is conducive to the gasification and escape of ash in carbon graphite. Causes poor carbon graphite purification effect

3.The heating curve of the carbon graphitization process. Using a large current to heat up, the carbon graphitization temperature rises quickly, which is conducive to the gasification and escape of ash in the dispersed carbon graphite.

4.The particle size of the raw material. Generally speaking, the smaller the particle size, the better the purification effect.

Carbon graphite is an important resource in non-metallic resources, and major enterprises have higher requirements on the wear resistance and corrosion resistance of carbon graphite. The carbon graphite of the Franli factory itself has very superior performance and physical properties, which promotes the optimal allocation of market resources and the development of the graphite industry. At present, the high-purity carbon graphite from the Franli factory has replaced metallic materials and organic materials in many fields, and the quality is very good.