PBN crucibles are deep-bottomed vessels for heating solids (especially high melting point materials), which can withstand higher temperatures than glassware or other common crucibles. When using PBN crucibles, they are usually used to prevent heated materials from jumping out and to allow air to flow in and out freely to allow for possible oxidation reactions.
The crucible is usually covered by an inclined lid. As the bottom of the crucible is usually small, it is usually placed in a slurry pan and heated directly over a fire. The crucible may be mounted on a steel tripod which can be tilted in a positive or vertical direction.
It can be mounted according to the needs of the experiment. After heating, do not immediately place it on a cold metal table to avoid damage due to rapid cooling. Do not place it immediately on a wooden table either, as this may burn the table or cause a fire. The correct way to cool them is to place them on a steel tripod or on an asbestos net to cool them slowly. Use a pair of crucible pliers.
Main uses of PBN crucibles.
(1) Evaporation, concentration or crystallization of solutions.
(2) Incineration of solids.
Precautions for use
(1) Can be heated directly and does not switch off when removed with tongs after heating.
(2) Can be placed on an iron stand when heated.
(3) Drying by shaking during evaporation and waste heat during steaming.
Having described PBN crucible, we will look at other crucibles. There are three main types of digesters: graphite digesters, clay digesters and metal digesters. Within the graphite digesters, there are three types: general purpose graphite digesters, heterogeneous graphite digesters and high purity graphite digesters.
The types of graphite crucibles differ in terms of characteristics, applications, conditions of use, raw materials, manufacturing methods, processing techniques and product design specifications. The main raw material for graphite crucibles is natural crystalline graphite. As a result, it retains several physical and chemical properties of natural graphite, such as good thermal conductivity and resistance to high temperatures.
When used at high temperatures, it has a low coefficient of thermal expansion and is, to a certain extent, resistant to rapid heating and cooling stresses. Strong corrosion resistance in acid and alkaline solutions and excellent chemical stability.