Silicon carbide vs Boron carbide
Silicon carbide and boron carbide are commonly raw materials in the grinding and ceramic industries. Both the two materials have high hardness and high-temperature resistance. However, both silicon carbide and boron carbide have different characteristics in terms of usage scenarios and high-temperature performance.
These characteristics and differences of silicon carbide & boron carbide are in the following aspects:
In the field of grinding, the hardness of a material is one of the key indicators of grinding capability. At room temperature, the Vickers hardness of silicon carbide is 28-34GPa, and the Mohs hardness is 9.2-9.5. The Vickers hardness of boron carbide is 35-45GPa, and the Mohs hardness is 9.3. Silicon carbide is usually classified as a traditional abrasive, while boron carbide is classified as a superhard abrasive. However, the high-temperature strength of these two materials exhibits different variations. When the temperature reaches 1000 degrees, the hardness of silicon carbide will decrease to 17-18 GPa. At the same temperature, the hardness of boron carbide can still be maintained above 30GPa. In addition, silicon carbide and boron carbide are both brittle abrasives. But the toughness of silicon carbide is higher than that of boron carbide and lower than that of corundum.
Fire resistance performance. The asynchronous melting point of silicon carbide can reach 2750 degrees, while the melting point of boron carbide is 2450 degrees. All belong to high-temperature refractory materials. Nevertheless, their uses vary greatly. Silicon carbide has better thermal shock resistance, high-temperature strength, and toughness than boron carbide. In the meantime, the cost of SiC is much lower than B4C. Silicon carbide is more widely used in the field of high-temperature resistance.
The theoretical density of silicon carbide is 3.2g/cm3, and the theoretical density of boron carbide is 2.52g/cm3. In the field of manufacturing engineering ceramics, both are commonly used ceramic materials. However, boron carbide has the lowest density among known ceramic materials and can be used for the production of aviation component ceramic parts.
Antioxidant performance. Silicon carbide has good antioxidant properties, and silicon carbide below 1000 degrees Celsius can maintain good stability. At a high temperature of 1000 degrees, the silicon dioxide film formed on the surface of silicon carbide will protect it from further oxidation. When the temperature rises to 1600 degrees, the SiO2 that prevents alumina will lose its effect, and the oxidation resistance of silicon carbide will disappear. However, the oxidation resistance of boron carbide is not as good as that of silicon carbide. It begins to oxidize at around 600 degrees Celsius and oxidizes very clearly at high temperatures of 800 degrees Celsius, making it particularly prone to react with metals. In this way, silicon carbide is not only suitable for grinding and polishing ceramics and glass but also for grinding metal materials such as aluminum alloys and brass alloys. Boron carbide is more suitable for grinding and polishing sapphire crystal materials.
Silicon carbide is generally used for grinding raw materials for sandblasting and grinding tools, mainly for processing materials such as ceramics, jade, stone, glass, etc. Silicon carbide is a good raw material for anti-corrosion coatings and adhesives due to its superior antioxidant performance. Although boron carbide is commonly for grinding sapphire crystals, it is difficult to make grinding tools. The function of boron carbide composite materials mainly works in the fields of neutron absorption and radiation protection. The application in which silicon carbide and boron carbide work together is ceramic products. Wear-resistant ceramic parts can be made by mixing silicon carbide powder, boron carbide powder, and alloy powder in a certain ratio and using reaction sintering or hot pressing sintering processes. The composite ceramics produced have the advantages of high wear resistance, strong impact resistance, and stable chemical properties, and have a wide range of application prospects.
