Fig. Application example of tungsten carbide

Production fine particles

The cemented carbide material is very difficult to grind or disintegrate because of high hardness. In general fine particles of the cemented carbide material is produced by chemical synthesis. Top size of such particles is often more than 10 μm due to hard agglomeration or sintering during drying. It is required to disintegrate it to the size of primary particles. However, carbon material is harder than the machine construction material, therefore high wear is expected in the mill interior parts. Because of these characteristics, mechanical grinding is not suitable for this application. In order to grind carbides to super fine powder, the fluidized bed opposed jet mill AFG is most suitable choice.

Enhancement of cemented carbide material
R&D works for the production of high end electrical materials have been actively conducted, by the precise dispersing the cemented carbide with metal and ceramics particles. The cemented carbide for this purpose is so fine (below a few microns) that they are highly cohesive and adhesive. For ordinary mixer, fine dispersing is very difficult since it generates agglomerates or lumps. This is why wet dispersion is normally adopted. However, wet process required drying process and cohesion during drying is inevitable. Selection of suitable solvents or dispersing agent is the issue and recovering solvents is problematic.


                                       Flow of AFG

                                          Schematic figure of composing

  Dry particle coater Nobilta NOB-300



Grinding system, the fluidized opposed jet mill, wear protected AFG
The fluidized opposed jet mill AFG with wear protection version can be applied; particle to particle milling. Different from the mechanical mill where the particles are impacted by machine parts, the particles are collided each other in AFG mill, so the wear is minimized during grinding. Compressed air nozzles are in wear protected version to avoid wear on the outer side of the nozzle. In addition, classifying rotor and casing are constructed in ceramics and/or rubber lining for wear protection.

 AFG with ceramics sprayed interior


Precision Mixing, Dispersion

Compositing system, Nobilta NOB
Cemented carbide particles are often used in the application of lowering the sintering temperature by mixing with other materials, or for high functionality, in addition to single use of the material. However, the carbide is highly adhesive and cohesive so that the ordinary mixer cannot disperse the material. For the purpose of such material, a machine with high share force exceeding cohesive force is required. It is expected to enhance the functionality of the material through the operation that dispersing and coating the fine carbide particles on the core particles. Nobilta system is suitable for such fine dispersion of super fine particles or compositing. This system realizes the fine dispersion of the particles in dry phase or coating/compositing by strong impact, shear and compression forces. By dispersing fine particles over the surface of core particles and embedding them and segregation is eliminated and various functions can be added on one composited particle from different particles.

    Ultra fine composite particle


Dry Compositing

To avoid such problems, it is desperately needed to mix components in dry process so that production cost is reduced and high performance is realized. To meet these requirements, the particle compositing system Nobilta with wear protection is most suitable.