Introduction to Various Ceramic Crucibles

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Crucibles, as an important component of chemical equipment, are containers for melting and refining liquid metals and heating solid-liquid reactions. It is the foundation for ensuring the smooth progress of chemical reactions.

Crucibles, as an important component of chemical equipment, are containers for melting and refining liquid metals and heating solid-liquid reactions. It is the foundation for ensuring the smooth progress of chemical reactions.
From a historical perspective, crucibles were originally made of clay, and one of the earliest uses of platinum was also to make crucibles. But with the development of preparation technology, crucibles can now be made from any material that can melt or change its contents.
There are many types, models, and specifications of crucibles, which can be freely selected and have strong applicability, ensuring the purity of smelting materials.
Ceramic crucibles are an important component of crucibles. Ceramic crucibles can be divided into quartz crucibles, corundum crucibles, boron nitride crucibles, zirconia crucibles, etc. according to their raw materials, and their performance and use are different.
1. Quartz ceramic crucible
Quartz ceramic crucible, full name of high-purity fused silica ceramic crucible (silicon dioxide content ≥ 99.9%), is a ceramic crucible made of high-purity fused silica as raw material. With fine structure, low thermal conductivity and low coefficient of thermal expansion, quartz ceramic crucible has good thermal shock stability, good electrical performance and good chemical resistance, and is widely used in glass deep processing industry, metallurgy industry, electronics industry, chemical industry Aerospace and other fields. In general, its shape is mainly square and cylindrical.
With the importance and development of environmentally friendly energy, solar energy as a green energy source has received widespread attention from countries around the world. The rapid increase in the amount of polycrystalline silicon used for solar energy conversion has promoted the rapid development of polycrystalline silicon production. Therefore, the number of corresponding large-sized thin-walled square fused silica ceramic crucibles is also increasing rapidly, and their market prospects are very broad worldwide.
2. Corundum (alumina) crucible
Corundum crucible, also known as alumina crucible, is commonly referred to as a corundum crucible when the alumina content is above 95%. The corundum crucible is sturdy and resistant to melting, high temperature, acid and alkali, rapid cooling and extreme heat, and chemical corrosion. Suitable for melting samples with weakly alkaline substances such as anhydrous Na2CO3 as a flux, but not suitable for Na2O2, NaOH, etc. Strong alkaline and acidic substances are used as fluxes to melt samples... Alumina crucibles with a purity of 99.70% exhibit excellent high-temperature insulation and mechanical strength in an oxidation-reduction atmosphere between 1650 ℃ and 1700 ℃, with a maximum temperature of up to 1800 ℃ in a short period of time. According to the application conditions, alumina crucibles have various sizes and shapes to choose from.
3. Boron nitride crucible
The commonly used types of boron nitride are cubic boron nitride (C-BN) and hexagonal boron nitride (P-BN). Among them, boron nitride crucibles are usually composed of P-BN. P-BN ceramics have good heat resistance, thermal stability, thermal conductivity, and high-temperature dielectric strength, making them ideal heat dissipation materials and high-temperature insulation materials.
Due to its excellent chemical stability, P-BN can resist the corrosion of most molten metals. Due to its high temperature insulation characteristics, high thermal conductivity, and low thermal expansion, P-BN is most suitable for strict environmental conditions, such as semiconductor manufacturing processes. Based on the materials used. P-BN crucibles are commonly used for smelting metals and semiconductors. It can be used at temperatures up to 1800 ° C under vacuum and up to 2100 ° C under atmospheric protection. Generally, nitrogen or argon gas is used for protection (atmospheric protection is to prevent crucible oxidation).
4. Zirconia crucible
The melting point of zirconia is higher than that of zirconia, reaching 2700 ℃. It is one of the best refractory materials in nature. Reactions such as slag occur, so crucibles made of zirconia materials can successfully melt platinum, palladium, ruthenium, cesium and other platinum group precious metals and their alloys.
It is worth noting that although zirconia is more expensive than alumina, it is a special oxide refractory material that cannot be replaced by other oxide materials when used in high-temperature furnaces above 2000 ℃.
5. Yttrium oxide crucible
Y2O3 ceramic is a high-performance ceramic with excellent heat resistance, corrosion resistance, and high-temperature stability. The melting point of yttrium oxide is greater than 2400 ℃, making it difficult to react with some active metals (such as Ti, Al, Hf, Nb, etc.) at high temperatures. Crucibles with high-purity Y2O3 as the main component may be used for melting Ti and Ti alloys, or any oxygen sensitive melting process.
However, due to the high melting point of Y2O3, the processing is difficult. Some foreign manufacturers use the hot isostatic pressing (HIP) method for preparation. At the same time, the manufacturer also stated that due to the brittleness of Y2O3 itself, if the heating or cooling rate is too fast (as indicated by the manufacturer above 5 ℃/min), the crucible may break.