Box furnace vs muffle furnace
Box furnaces (also called Ash furnaces) have many applications in modern research and chemistry laboratories. These furnaces are used to determine the amount of non-combustible and non-volatile (ash) material in a sample. To determine the ash quantity, a sample is placed in the furnace and exposed to high temperatures (typically up to 1,100°C) for a given period of time. The combustible and volatile material in the sample is burned off and removed from the furnace, typically as gas.
The furnace is placed in a fume hood during operation to allow safe venting of the gas. The remaining material in the furnace after the procedure is complete consists entirely of ash which is not burned off at high temperatures. This process is commonly used for coal and petroleum coke ashing procedure
A muffle furnace is used for many of the same types of protocols as an ashing furnace. The use of mechanical convection in these ovens directs airflow out of an exhaust muffle, so typically does not require placing the furnace within a fume hood.
Common applications for a muffle furnace include high-temperature applications such as fusing glass, creating enamel coatings, ceramics and soldering and brazing articles. Also, advances in materials used for heating elements, such as non-flammable molybdenum disilicide, can now produce working temperatures up to 1,800 degrees Celsius (3,272 degrees Fahrenheit), which facilitate more sophisticated metallurgical applications.