WIDIA Hardmetals
In Germany hardmetal is often referred to coloquially as
Widia, the trade name given to a sintered hardmetal cutting
material which was first brought on to the market in 1926.

Sintered hardmetals are made by powder metallurgy and
in the most simple case consist of tungsten carbide(WC)
as a source of hardness, & cobalt(Co), which is primarily
responsible for toughness. Titanium carbide and /or tantalum

 carbide or niobium carbide are added to improve high-
temperature properties. This applies particularly to oxidation
resistance, hot hardness, elevated - temperature strength and
diffusion resistance in the presence of iron -base alloys.
Hardmetals attain their final properties at sintering
temperatures of around 15000C.

The following diagram illustrates the interesting process:

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  1. Tungsten oxide (WO3) powder produced from
    tungsten ores such as scheelite and wolframite
  2. Reduction of tungsten oxide in hydrogen at about
    8000C
  3. Tungsten (W) powder
  4. Carbon (c) powder
  5. Blending of tungsten powder and carbon powder
  6. Carburising of the tungsten/carbon mixture at
    elevated temperatures (e.g. at 15000C)
  7. Tungsten carbide (WC) powder
  8. Cobalt (Co) powder
  9. Griding and mixing in ball mills
  10. Pressing of the powder mix
  1. If neccessary, pre-sintering of the compacts at about
    7500C
  2. Shaped compact
  3. Finish-sintering at about 15000C
  4. Tip of WIDIA hardmetal

     A-F TiC and TaC are added to some hard metal grades
             to achieve specific properties

  1. Titanium dioxide (TiO2) powder
  2. Carbon (C) powder
  3. Blending of titanium dioxide and carbon powder
  4. Carburizing of the titanium dioxide/ carbon mix at
    elevated temperatures (e.g at 18000C)
  5. Titanium carbide (TiC) powder
  6. Tantalum carbide (TaC)powder

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