Sintered ndfeb magnet production technology introduced two key process
In the previous section we have introduced the production technology of sintered ndfeb magnets inside the first step: ingredients and the second step: smelting, now let's explanation of ndfeb magnet production step 3: broken.
(3) crushing, powder sintered ndfeb magnet broken first divided into coarse crushing, crushing and hydrogen into powder, flour is the purpose of to large pieces of alloy ingot or with pieces of broken to a certain size of powder, mainly USES a hydrogen explosion + airflow grinding method.
Will be melting alloy ingot or quick-setting piece into the furnace, vacuum to 10 -
Under 2 pa, then filling the high purity hydrogen and the hydrogen pressure reached about 105 pa, about 20 -
After 30 min, you will hear the crash, and the furnace temperature will rise.
Alloy hydride forms after hydrogen absorption and make its burst, as hydrogen cracking, hereinafter referred to as hydrogen detonation, namely the HD (
Magnets in hydrogenation reaction is exothermic reaction, thus makes the furnace temperature.
HD handling magnet can be broken into 45 ~ 355 mm range of particles, most of the particles is about 125 mm.
If the hydrogen absorbing - several times
Dehydrogenation circulation processing, can make its powder particles further reduce to less than 10 mm.
HD is the hydrogen equipment used to break the furnace.
Will further using the airflow mill (HD powder
JetMilling, referred to as JM)
Broken, can make the secretion to 2 ~ 5 mm, so the size of the powder can be directly used to produce sintered magnets.
Airflow grinding powder is the use of air flow the powder particles accelerated to Seattle to collide with each other and broken.
Jet mill of commonly used equipment is the airflow grinding powder machine.
HD + JM has become an important system of sintered ndfeb magnet powder method.
Shown below for hydrogen furnace and airflow grinding machine pictures.