NdFeB hydrogen-breaking technology is the high performance, high-quality sintered NdFeB an indispensable step in preparation.
HD technology is the so-called ingots or rejection by H2 with film processing (reaction at room temperature or 200 oC or so, H2 pressure is generally less than 0.3 MPa), and dehydrogenation at 400 ~ 600 oC.Hydrogen reaction in two steps: first in the Nd-rich grain boundary phases were (at room temperature can be), then at a certain temperature and the main phase Nd2Fe14B reaction [1, 2], the reaction temperature up to 300 oC. Reaction mechanism can be simply expressed as follows:Hydrogen: Nd2Fe14B (main phase) Nd (Nd-rich phase) H2 Nd2Fe14BHx NdHy,Under normal circumstances x = 0.4, y = 2 ~ 3.It is because of the boundary phase and the hydrogen atoms into the crystal lattice inside the NdFeB original lattice is destroyed, or thrown with a massive ingot pieces swell, in order to achieve NdFeB hydrogen fragmentation (referred to as "hydrogen-breaking"). After breaking through the hydrogen, the general will become less than 1mm ingot powder, and thrown into a zone plate will generally be less than 0.5mm powder.Dehydrogenation has two steps: first in the 200 ~ 300 oC NdFeB main phase dehydrogenation, and then 350 ~ 650 oC some Nd-rich phase dehydrogenation. Dehydrogenation mechanism can be simply expressed as follows:Dehydrogenation: Nd2Fe14BHx NdHy Nd2Fe14B NdH2.Actual production in general use 400 ~ 600 oC dehydrogenation, dehydrogenation incomplete at this time, the hydrogen content is generally less than 2000ppm. Dehydrogenation in the sintering continues, the third dehydrogenation of the main peak at about 800 oC, until about 1000 oC dehydrogenation to complete.Hydrogen breaking technology features are as follows: After breaking the hydrogen treatment, the ingot or rejection with NdFeB film has become very loose after the break, then break into the jet mill or hydrogen directly into the jet mill. At this point the speed of traditional craft flour 2 to 3 times, greatly improving the efficiency of jet mill, cost savings. After breaking the hydrogen out of material not only improves the speed, and can be more fine grinding NdFeB (eg 2.8 ~ 3.5m. The traditional process is generally 3.8 ~ 5.0m.), Which can make the finished grain size of 10 magnets m or less (the traditional process of grain size of 20 ~ 40m). Smaller mean grain size of the coercivity increase, while greatly improving the corrosion resistance ability of the magnet. Traditional craft magnets weight loss (125 oC, 0.2 MPa, 72hrs, PCT test) is generally 150 mg/cm2, while the hydrogen is generally less than after breaking 5 mg/cm2. Magnet weight loss reduced the plating becomes easy to help solve the long plagued China Sintered NdFeB plating problems.This equipment is designed for these purposes is made based outside the thermal, hydrogen rotary equipment.In terms of security, to take a Shimadzu and NKE and essentially the same design, with the safe operation of the gas lock system, including the demolition drive, pressure relief valve (two), power-off protection automatically argon, hydrogen negative charge automatically argon slow reactions. Dehydrogenation of external thermal heating, and Shimadzu and NKE's design is not the same. Dynamic seal to magnetic fluid seal technology, the magnetic coupling with different NKE. Strong cooling of cold water spray cooling.Furnace using fast docking flange mounted type, NdFeB materials are not in contact with air, put out the materials are very simple materials and materials to prevent the possible oxidation problem. As a result of rotation, so suck, dehydrogenation thorough, uniform.
Automatic hydrogen broken furnace
