VIDREMOT coating



Non uniform carbide distribution

Non HVOF Coating

Carbide degradation

Induction fusing

Of course we use the best spraying systems available. In 1995 we installed our first HVOF equipment, and since 1998 all our plungers are sprayed with hybrid HVOF equipments. The low temperature of the flame (2600 ÂșC) together with the high kinetic energy (particles travel at a speed of 400-1000 m/s) gives us the following benefits:

  • High carbide integrity although we are using very fine carbides (1-3 microns)
  • Low oxidation
  • Dense and well bonded coatings

After spraying the coating has to be fused. The fusing can be done by induction heating or by an oxy-acetilene flame.

Although it is a more expensive process we have choosen the second as it gives a better quality of the coating (no carbide degradation specially on the tip, no contamination from the base material, better control of the fusing temperature).

With fusing you obtain:

  • Adhesive strength (> 80 MPa), we change from a mechanical bond to a metallurgical bond (interdiffusion)
  • Cohesive strength: nearly 0% porosity, B and Si dissolve oxide to form borosilicates, uniform distribution of phases
  • Stress relieving