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Coercivity Force in Quality Control of the Tungsten Carbide Products |
| Author : Date : 2011-11-3 17:11:35 |
Coercivity Force in Quality Control of the Tungsten Carbide Products
The ferromagnetic cobalt is contained in the tungsten carbide material which result in stress when in the sintering process due to different thermal expansion coefficient between it and the WC.In the production of the tungsten carbide products ,coercivity is a very critical guideline of its performance.
When the tungsten carbide part is placed in the electromagnetic coil with current ,it is magnetized with a certain magnetic filed strength reached.In the meantime ,if the alloy’s magnetic induction is saturated ,it would not increase any more even if rise of the magnetic filed strength .
However when the magnetic field strength low to zero ,the alloy’s magnetic induction strength is unavailable to be reduced to zero, consequently ,there is very small amount of magnet left in the tungsten carbide products ,and need a contrary-direction magnetic field strength to eliminate the left magnet ,which is call coercivity HC with unit as KA/M.The coercivity value has very important connection with the inner structure of tungsten carbide products. We can measure the grain size of WC by the coercivity.When the cobalt content is fixed ,and carbon composition is appropriate and stable ,the coercivity force decreases as growing of grain size.Therefore ,if rised the sintering temperature for the same material ,its coercivity force is down.
Owing to this corresponding relationship between the grain size and coercivity force,we can take some means to control the sintering process indirectly ,so as to get ideal microstructure and physical properties .This way is simple ,prompt meanwhile ,it is also the most promising mean of inspection methods .
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