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Tungsten crucibles

Use

Tungsten crucibles, thanks to their resistance to certain molten metals and metal oxides, have found wide use in technologies for growing monocrystals from molten corundum, as well as in electronics and technologies for thermal vaporization - deposition of various substances.

Chemical composition

Guaranteed chemical composition of the material in tungsten crucibles W-PM
Grade W, % minimum Impurities, ppm, maximum
Crucible W-PM 99.0 Fe Ni Al Mo Si K Na Ca As
80 50 10 400 30 200 150 50 50

Upon agreement with the client, crucibles can be prepared with additions of molybdenum of up to 0.9%, and with other requirements regarding the material's chemical composition.

Shapes, dimensions and surface condition of W-PM crucibles

Crucibles are made in accordance with drawings. The shape and dimensions are agreed upon with the client. The surface roughness of tooled crucibles does not exceed Rz 6.3.

Sample dimensions of sintered tungsten crucibles W-PM, diameter Ø x height, mm:

  • Ø130x150;
  • Ø200x240;
  • Ø240x300;
  • Ø250x350-400;
  • Ø330x350;
  • Ø330x450;
  • Ø338x460;
  • Ø350x460;
  • Ø350x495;
  • Ø380x530.

Modestly sized crucibles made form tungsten - for example, with diameters of 40-50 mm - can be produced based on drawings agreed to with the client.

 

Crucible density:

  • Sintered crucibles W-PM – at least 17.8 g/cm³;

Advantages:

  • the products' fairly high chemical purity, which ensures sapphire monocrystals free from impurities;
  • a fairly wide selection of standard product sizes, to quickly fulfill consumers' order;
  • the ability to develop products with new sizes based on the client's individual needs.

Recommendations on using and storing crucibles.

Before use, it is recommended that the consumer anneal (de-gas) crucibles in a vacuum without batch charging.

In a furnace, the annealment process should be supported with a vacuum at P < 10-4 mmhg

Heating and cooling technique:

  1. raise temperature (T) to 1000 ºC over a period of 3 hrs;
  2. hold at T=1000 ºC for at least 1 hr;
  3. raise to T=1400-1500 ºC for at least 1 hr;
  4. hold at T=1400-1500 ºC for at least 1 hr;
  5. raise to T=2000-2200 ºC for at least 1 hr;
  6. hold at T=2000-2200 ºC for at least 1 hr;
  7. cool crucibles in furnace.

When preparing a crucible for work, the consumer should not allow a sharp rise or fall in temperature or abbreviate the recommended time periods for holding temperatures.

While preparing the crucible for work  and during operation, it should not be subjected to shocks.

The manufacturer packs crucibles into wooden packaging (crates) with crash pads. During transport and storage, the crucibles are not submitted to sharp jolts or shocks. They are stored in the manufacturer's packaging in closed, dry fnd heated warehouses.