Application of tungsten and molybdenum in high temperature furnace construction materials
Due to the metal, ceramics, such as composite materials, the requirements of modern manufacturing technology for its heat treatment has become higher and higher, so the relevant production conditions have become increasingly stringent. Almost all kinds of metals involved in the sintering process need to adjust the atmosphere gas in the furnace, and most of them adopt vacuum or non oxidizing atmosphere gas furnace for annealing, hardening and rolling. The high temperature furnace used to apply such treatment must use special metalwork as the internal construction material. In addition to high temperature resistance, the metal used also needs to meet the conditions of high purity and low vapor pressure.
Tungsten and molybdenum materials are ideal structural components of high temperature furnace, and have the following application ranges:
(1) Wire, beech, plate or mesh hole heating parts for high temperature furnace;
(2) Shielding insulation material or heat reflecting plate for heat protection of furnace wall;
(3) Heating devices such as heating boat, disc body, slide way and grid frame in heating furnace shall be made of such materials before feeding into furnace;
(4) Temperature monitor or control thermocouple, protection tube, etc.
1. Pusher furnace
Pusher type high temperature furnace (≥ 1700°C) is a kind of hot fireplace, which is usually used to sinter metal and ceramic powder in non oxidizing or reducing atmosphere (H2, N2, H2 + N: mixture). This type of furnace body is equipped with long cooling water tanks at both the inlet and outlet sides. The heating zone is composed of ceramic (aluminum series) hearth and furnace wall composed of refractory bricks, and the outer wall is formed by bending iron series metal plates. There are long rod like (or several wires twisted) molybdenum heater, there are also ribbon type molybdenum heater is used to place in the heating zone. At the same time, there are also molybdenum heater from the furnace, the upper vertical type of lifting into heating zone.
In this kind of furnace, the parts used to transport the burned materials are the burning boat and the heating plate. Usually, this kind of heating plate is not made of molybdenum plate folded up and then overlapped with rivets. It must be manufactured by deep stranding. The recrystallization energy and recrystallization energy of the alloy doped with Mo (TM) are still better than those of the alloy with Zr-0.080.
2. Intermittent heating furnace
Batch heating furnace is usually used to deal with the large volume items which are difficult to be fired by the pusher furnace, which has the ability of rapid heating and cooling. Therefore, it is necessary to accurately control the heating, holding and cooling of the furnace body according to the specific situation of the object to be heated. According to the operating temperature of the furnace body, the material, shape and size of the material to be treated, it is suitable to use relatively cheap. Mo products at about 1800°C. It still has continuous service ability. Of course, TZM and La2O3 doped Mo alloys have better high-temperature characteristics than Mo. So it is widely used. The difference between the Mo doped parts and the vacuum heating parts is shown. Through this comparison, it is not difficult to find that the deformation of La2O3 doped Mo heating parts is smaller. In addition to the rod-shaped heating parts shown here, there are plate-shaped, reticulated and other heating components used in production. In addition, tungsten has been used in high temperature heating above 2000°C because of its high price, high melting point and low vapor pressure.
