When the furnace temperature needs to be above 1200 ℃, it is usually necessary to use the silicon molybdenum rod as the heating element of the experimental electric furnace, that is, as the heating rod of the furnace. The main component of the silicon molybdenum rod is molybdenum disilicide. Because of its high brittleness at room temperature and plasticity at high temperature. Generally, the installation methods and precautions for heating elements of high temperature experimental furnace are as follows:
1. Vertical suspension:
A good installation method for U type elements is vertical suspension, and the elements are vertically suspended on the furnace top through the support chuck. The purpose of such installation is to avoid the mechanical stress applied to the heating end of the element, otherwise it is easy to cause the element to break.
2. Support collet:
The supporting collets are respectively used for 9 / 18mm and 6 / 12mm diameter components. The weight of the whole element is borne by the supporting chuck, and the position of the element is determined by it. Therefore, it must be installed carefully to ensure the vertical suspension of components. In order to avoid local overheating, the conical part at the lower end of the element must extend into the furnace.
3. Conductor collet:
The conductor of contact element shall be aluminum braided wire or multi-layer aluminum foil. The steel plate on the outside is only used for clamping, not for conducting electricity. 6 / 12mm diameter elements shall be single row, while 9 / 18mm diameter elements shall be double row. The end of the conductor is connected with the bus. In order to avoid stress transfer to components, the conductor should be slightly larger than the straight-line distance between components and bus. When installing the components, the screws on the collet should not be tightened too tightly at one time. When the components rise to high temperature, they should be tightened again, because at this time, the components are plastic and not easy to break. Generally, the temperature of collet part should not be higher than 200 ℃. Therefore, the contact voltage between the collet conductor and the element should be reduced by 0.1V. In order to avoid radiation heat transfer to the collet, the distance between the lower end of the collet and the top of the through brick shall not be less than 50mm. In order to avoid damage, generally 6 / 12mm diameter components cannot be used for 170a for a long time, and 9 / 18mm diameter components cannot be used for 300A for a long time.
On 2018-08-08 11:45:46
