Hollow corundum microspheres Ni-HCM
The main feature of the use of nickel-coated hollow corundum microspheres (Ni-HCM) is their self-sharpening capability due to pore-forming agents in diamond grinding wheels, diamond tools, diamond cutting wheels and grinding stones.
The strength of a diamond grain is much higher than that of a Ni-HCM microsphere; therefore, it is the diamond grains that cut and tear the metal part, while "exposed" Ni-HCM microspheres remove metal burrs and then crumble, forming new sharp edges.
This self-sharpening effect helps to achieve the following:
- Smaller surface roughness of the processed metal in one pass of a diamond tool with 15-30% Ni-HCM.
- Improvement of the cutting properties of the abrasive tool due to the presence of Ni-HCM microspheres increases the service life of a diamond tool by 30-50%.
- Artificial porosity in diamond tools helps to reduce grinding time.
- The abrasive tool does not need resharpening, as the internal cavity of Ni-HCM and the space around it is cleaned with liquid, effectively increasing the quantity of processed metal products and prolonging the life of the abrasive tool.
- High adhesion properties of Ni-HCM when bonding to metal or plastics provide for attachment of microspheres to a diamond tool.
Properties of Ni-HCM
- Main material: theta and alpha aluminum oxide Al2O3 (corundum);
- Coating layer: nickel metal 3-25 PBW;
- Spherical shape
- Increased particle surface, cm2/cm3;
- Particle size: 5-200 µm;
- Bulk density: 1.8-2.4 g/cm3;
- Refractoriness: HCM - 1700-1800°C;
- High mechanical strength, up to 120 MPa;
- High abrasive properties;
- Excellent adhesive properties when bonding to metal and plastics.
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Types of hollow corundum microspheres with nickel coating (Ni-HCM)
LOI*, % - relative mass change when baking