Brown Fused Alumina Manufacturing Process and Raw Materials Introduction
Silicon carbide (SiC) is an important industrial material widely used in abrasive, cutting, and polishing applications. Based on its color and performance, silicon carbide is mainly divided into green and black types. In this article, we will explore in detail the processes of green vs. black silicon carbide and their respective application fields.
The production process of both green and black silicon carbide starts with raw material preparation. The main raw materials are quartz and petroleum coke. During the preparation phase, these raw materials are mechanically processed to the suitable particle size and then mixed according to chemical calculations into furnace charges. For the preparation of green silicon carbide, a certain amount of salt needs to be added to the furnace charge.
The furnace charge is placed into a batch-type resistance furnace, with graphite electrodes installed at both ends of the furnace, and the core of the furnace connected between the two electrodes. The temperature of the resistance furnace can reach 2600~2700℃ , causing the furnace charge to react at high temperature. Over time, silicon carbide gradually forms within the charge, and carbon monoxide is produced through high-temperature decomposition. Adjusting the relationship between power input and time during the production process is a crucial step to ensure the quality of silicon carbide.
During the production process, the materials inside the furnace can be divided into several layers: unreacted materials, the silicon-carbon-oxide layer, the adhesive layer, the amorphous layer, second-grade silicon carbide, first-grade silicon carbide crystalline blocks, and the graphite core of the furnace. Different layers of materials have different uses in subsequent treatments, for example, first-grade silicon carbide crystalline blocks are the main product of the resistance furnace, containing over 96% SiC, and are used for high-demand abrasive applications.
Applications of Green Silicon Carbide
Green silicon carbide appears green and contains over 97% SiC. It has extremely high hardness, with a Mohs hardness of 9.5 and a microhardness of 3280-3400 kg/mm², positioned between corundum and diamond. Green silicon carbide is mainly used for high-precision abrasives, such as the cutting and grinding of solar silicon wafers and semiconductor silicon wafers. It is also widely used for the polishing of crystals, pure iron, ceramics, special steel, and other materials. Furthermore, green silicon carbide is used in the manufacture of advanced refractory materials, engineering ceramics, and thermal elements.
Applications of Black Silicon Carbide
Black silicon carbide appears black, with hardness slightly lower than green silicon carbide, having a Mohs hardness of 9.2. It has excellent thermal conductivity and electrical conductivity, mainly used for the production of bonded abrasives and coated abrasives. Black silicon carbide is suitable for the cutting and grinding of solar silicon wafers, semiconductor silicon wafers, and quartz chips. It is also widely used for the grinding and polishing of stone, as well as for processing low-strength metals and non-metallic materials such as cast iron, brass, aluminum, and refractory materials.
Although the production processes of green and black silicon carbide are similar, their application fields differ due to their respective performance characteristics. Green silicon carbide, with its superior hardness and cutting ability, is suitable for high-precision industrial applications, while black silicon carbide, with its good thermal conductivity and cost-effectiveness, is widely used for everyday abrasives and other industrial fields. Understanding the production processes and applications of these two types of silicon carbide can help us better choose the appropriate materials to meet various industrial needs.
