The horizontal furnace is also called continuous sintering furnace. The molybdenum bars are placed in the loading boat. Each boat of sodium tungstate is placed with 12-18kg molybdenum bars (too much discharging is easy to collapse in the high temperature area). A small amount of zirconia powder is evenly scattered between the molybdenum bars to prevent the molybdenum bars from bonding with each other after sintering. In the process of continuous (or intermittent) pushing boat, the molybdenum bars are successively taken out from the discharge end after passing through the low temperature zone, high temperature zone and cooling end. Reasonable design of temperature curve of heating belt and control of pushing speed can ensure the correct sintering schedule of molybdenum bar.

In order to control the reasonable heating rate of sintering, Jiangsu sodium molybdate factory is to make the impurities in molybdenum bars volatilize fully before densification, prevent the cracking of sintered molybdenum bars, and obtain high quality molybdenum bars.

According to the specification of molybdenum bar and the particle size of molybdenum powder, the sintering temperature in high temperature zone is 1700 ~ 1850 ℃ and the sintering time is 3-5h. The horizontal muffle furnace with tungsten wire (or tungsten rod) used in our country can generally sinter 80-100kg molybdenum bars every day and night. Vertical tungsten bar (or tungsten mesh) furnace and medium frequency induction furnace belong to intermittent sintering furnace. Molybdenum bars are loaded in cold furnace state, generally 70-120kg per furnace. In order to reduce sintering bending, several molybdenum bars can be connected together with molybdenum wire (especially the induction furnace sintering can only be loaded vertically, which is easy to bend). After the furnace cover is covered, H2 (or vacuumizing) is used to adjust the power supply of the furnace, and the temperature is raised, kept, cooled and cooled along with the furnace according to the process specification. The sintering process curve is shown in figure 9-26b. The power supply time of the whole furnace period is about 10 h. After the power is cut off, hydrogen and water are stopped about 10-12 h later (or the vacuum pump is stopped after 3 h, and then h27-8 h later). Open the furnace cover and take out the sintered molybdenum bar. Its holding temperature and time are the same as that of horizontal sintering.