September 26, 2023

Application and precautions of various ceramic crucibles

As an important part of chemical equipment, crucible is a container for melting and refining metal liquid and heating solid-liquid reaction, which is the basis for the smooth progress of chemical reaction. Crucibles were originally made of clay, and one of the earliest uses of platinum was to make crucibles. With the development of manufacturing technology, crucibles can now be composed of any material capable of melting or changing its contents.

There are many types, models and specifications of crucibles, which can be selected arbitrarily, with strong applicability and can ensure the purity of the molten material. Ceramic crucibles are an important part of crucibles. According to the raw materials, ceramic crucibles can be divided into quartz crucibles, corundum crucibles, boron nitride crucibles, zirconia crucibles, etc., and are used in different occasions according to their different properties.

Quartz ceramic crucible (silica content ≥ 99.9%)Quartz ceramic crucible is a ceramic crucible made of high-purity fused quartz. It has the characteristics of fine structure, low thermal conductivity, small thermal expansion coefficient, good thermal shock stability, good electrical performance, and good chemical resistance. It is widely used in glass deep processing. Industry, metallurgical industry, electronics industry, chemical industry, aerospace and other fields. Generally speaking, the shapes of quartz ceramic crucibles are mainly square and cylindrical.

Corundum (Alumina) CrucibleCorundum crucible, the official name is alumina crucible, when the alumina content exceeds 95%, it is usually called corundum crucible. Corundum crucible is strong and resistant to melting, high temperature, acid and alkali, cold and extreme heat, and chemical corrosion. It is suitable for melting samples of weakly alkaline substances such as Na2CO3 without water, but it is not suitable for melting samples with water. Alumina crucibles are available in a variety of sizes and shapes depending on the application conditions.

Boron Nitride Crucible

Commonly used boron nitride types include cubic boron nitride (C-BN) and pyrolytic boron nitride (P-BN). Boron nitride crucibles are usually composed of P-BN. P-BN ceramics have good heat resistance, thermal stability, thermal conductivity, high temperature dielectric strength, and are ideal heat dissipation materials and high temperature insulating materials. P-BN crucibles are often used for smelting metals and semiconductors, and the temperature can be as high as 1800 degrees in vacuum.

Zirconia crucibleZirconia has a higher melting point than zirconium and is one of the most refractory materials in nature. Even when heated to 1900°C, zirconia will not react with molten aluminum, iron, nickel and platinum metals, silicates and acid slag, etc., so zirconia crucibles can successfully smelt precious metals such as platinum, palladium, ruthenium and cesium and its alloys.

Yttrium oxide crucibleYttrium oxide 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 ° C, and it is difficult to react with some active metals (such as Ti, Al, Hf, Nb, etc.) at high temperatures. This crucible has the potential to melt Ti and Ti alloys, or any oxygen-sensitive melting process. However, yttrium oxide has a high melting point and is difficult to process. Since yttrium oxide itself is very brittle, the crucible may crack if heated or cooled too quickly.

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