High vacuum heat treatment furnace

High vacuum heat treatment is a new heat treatment method developed with the development of precision machinery manufacturing industry, national defense and other cutting-edge industries. Especially in recent years, with the improvement of parts performance and precision requirements, the vacuum furnace has been paid more and more attention. In addition to the heat treatment of refractory and active metals, it is gradually applied to the fields of quenching, tempering, annealing, carburizing, nitriding and metallizing of iron and steel materials.

Compared with the conventional heat treatment, vacuum heat treatment can achieve no oxidation, no decarburization, no carburization, and can remove the phosphorus chips on the surface of the workpiece, and has the function of degreasing and degassing, so as to achieve the effect of surface bright purification. After vacuum heat treatment, the service life of parts can be increased by dozens or hundreds of times.

The common heating elements of vacuum heat treatment furnace are graphite heater, w or Mo plate heater. These heating materials are conductive bodies with low resistance. The diameter of electrode (cold end) of graphite heater is 1-3 times of that of hot end. The resistance difference between hot end and cold end is small. The voltage difference between the two ends of graphite heating body is small, and the heating body needs large current, Generally, the current of graphite heater is 3000a-15000a and the voltage is 5-10v, which is usually low voltage and high current. The larger the current, the larger the transformer, the thicker the diameter of the wire, the greater the voltage drop from one end of the wire to the other end, and the greater the electric loss; the larger the transformer, the greater the loss of the transformer; the cold end temperature of the heating body reaches more than 2000 ℃ and can not be directly connected, so the water-cooled motor needs to be connected after cooling the cold end with a large amount of cold water, which leads to large heat loss and high heating power. Therefore, the thermal efficiency of graphite heater is low. W. Or the electrical properties of Mo heater are similar to that of graphite, and the heat loss is relatively large.

As the conductivity of zirconium diboride composite ceramic U-shaped heater is 100 times that of graphite, the current of zirconium diboride is 250-300a and the voltage is 20-30v, which is usually low voltage and high current. Compared with the graphite heater, the transformer is much smaller and its loss is smaller.