- The particle size composition of aggregates refers to the proportion of particles of different sizes. Mixing particles of different levels in a certain proportion instead of using only one type of particle is to make graphite electrode products have higher density, smaller porosity, and sufficient mechanical strength. After mixing particles of different sizes in proportion, the gaps between large particles can be filled by smaller particles or powder. This is similar to the effect of mixing pebbles, sand, and cement in proportion when preparing concrete. However, the proportioning of graphite electrode products according to particle size is not only to improve product density, reduce porosity, and obtain sufficient mechanical strength, but also has some other functions.
Large particles play a skeletal role in the structure of graphite electrode products. Properly increasing the size and quantity of large particles can improve the thermal vibration resistance of the product (which is not easy to crack during rapid cooling and heating) and reduce the thermal expansion coefficient of the product. Moreover, there are fewer cracks and waste products during the pressing and baking processes of the product. However, if there are too many large particles, the porosity of the product will significantly increase, the density will decrease, and the mechanical strength will decrease. Moreover, it is difficult for the product to achieve a smoother surface during processing.
The function of small particles is to fill the gaps between large particles. The quantity of powdered small particles usually accounts for a considerable proportion during ingredient preparation, sometimes reaching 60% to 70%. Properly increasing the number of powdered small particles can reduce the porosity of the product, improve density and mechanical strength, and make the surface of the product smoother during processing. However, an excessive amount of powdered small particles will greatly increase the possibility of product cracks in processes such as roasting and graphitization, and the thermal vibration resistance and oxidation resistance of graphite electrode products will decrease during use. Moreover, the more powdered small particles are used, the more adhesive dosage is required. The residual carbon rate of binder (coal tar pitch) after calcination is generally around 50%. Therefore, excessive use of powdered small particles does not have much benefit on the quality of the finished product. Different varieties and specifications of graphite electrode products have different particle size compositions.
Post time: 3月-20-2024
