Crucibles Overview

All crucibles, alumina, magnesia and zirconia to name a few, are manufactured in Capital's own modern purpose-built facility in the Czech Republic where we press, cast and fire various materials into crucibles.

Product Range

Isopressed

Capital Refractories is able to supply a full range of isostatically pressed crucibles from 2 kg capacity to 75 kg, in different grades and qualities. We use a state-of-the-art semi-automated cold isostatic press. Cold isostatic pressing applies pressure to the workpiece in all directions producing products of uniform density. 

The advantages of Isostatically Pressed Crucibles are:

  • Wide range of qualities
  • Wide range of crucibles sizes
  • Smooth internal surface giving a reduction of inclusions
  • Consistent material properties throughout the crucible
  • Defect free - no casting bubbles etc
  • Uniform density throughout the product improving its resistance to thermal stress

Vibrocast

Crucibles are produced by vibration casting (vibrocast) when the required size or shape is uneconomical or impractical by the isopressing production method.

Capital Refractories can offer a range of vibration cast crucibles, including T-Pot Ladles:

Benefits
Complex shapes, e.g. internal pouring siphon

To complement our range of crucibles we also offer numerous ancillary products and materials used within the investment and related foundry industries.

Description

Quality Description
Alumina ..... General purpose crucible with good resistance to acidic and basic slags. Used for a wide range of alloys.
..... AL97I Superior erosion resistance.
..... AL88I Improved thermal shock resistance.
..... AL90C Combines excellent strength and thermal shock resistance with low reactivity.
..... AL92C Superior thermal shock resistance.
..... AL97C High resistance to slags.
Chrome Alumina ..... High resistance to slags. Preferred to alumina in more arduous applications.
..... CA93I Superior erosion resistance
..... CA84I Improved thermal shock resistance.
..... CA91I Specially formulated to withstand the most severe thermal shock applications.
..... CA93C Have a high resistance to slags and are preferred to alumina in more arduous applications.
Magnesia ..... High resistance to basic slags. Used in vacuum melting of Ni, Co and Fe based alloys.
..... MG88I Used in vacuum melting of Ni, Co and Fe based alloys.
..... MG95 Resistant to the special alloys used in semi-conductor and sputter target industries.
Mullite ML72I High thermal shock resistance. Resistant to basic slags.
Zircon ZN66I Good resistance to acidic slags. It is used for non-ferrous and precious metals.
Zirconia ..... High resistance to acidic slags. Used in the vacuum melting of superalloys and precious metals.
..... ZC93I General applications.
...... ZC95I High thermal shock resistance for noble metals.
...... ZC96I Fine grained structure for noble metals.
..... ZM94I Magnesia-stabilised with enhanced thermal shock resistance for superalloys.
..... ZY97I Suitable for cobalt & nickel superalloys.
Sillimanite ..... High performance with good thermal shock resistance.
..... SL58C Good resistance to iron and nickel based alloys.
..... SL70C Good resistance to thermal shock with good hot strength and resistance to iron and nickel based alloys.

Products suffixed "I" are isopressed, products sufficed "C" are cast.

Chemistry

Quality Al₂O₃ SiO₂ MgO CaO Fe₂O₃ Cr₂O₃ ZrO₂ + HfO₂
Alumina AL97I 97.5 1.6 - 0.1 <0.1 - -
Alumina AL97C 96.6 2.5 - 0.1 <0.1 - -
Alumina AL92C 92.1 7.2 - 0.1 <0.1 - -
Chrome Alumina CA93I 93.4 2.2 - 0.1 <0.1 3.6 -
Chrome Alumina CA84I 84.3 9.0 - 0.1 0.2 4.8 -
Chrome Alumina CA91I 91.5 2.2 - 0..1 <0.1 5.3 -
Chrome Alumina CA93C 93.0 2.8 - 0.1 <0.1 3.6 -
Magnesia MG88I 3.5 3.8 88.0 3.8 0.2 - -
Magnesia MG95I 0.5 0.8 95.0 2.5 0.1 - -
Mullite ML72I 71.8 25.7 - 0.2 0.5 - -
Zircon ZN66I 0.8 32.5 - 0.2 0.1 - 66.6
Zirconia ZC93I 0.8 1.2 - 4.0 0.1 - 93.0
Zirconia ZC95I 1.0 1.5 - 3.8 <0..1 - 92.9
Zirconia ZC99I 0.6 0.9 - 4.4 0.1 - 94.0
Sillimanite SL58C 59.1 35.9 0.2 0.2 0.7 - -
Sillimanite SL63C 63.8 34.2 0.1 0.2 0.5 - -

Properties

Quality Bulk Density (g / cm³) Apparent Porosity (%) Thermal Expansion (x10⁻⁶ / K) Thermal Conductivity (W / m K) Maximum Service Temperature (°C)
Alumina AL97I 2.95 23.8 8.0 4.2 1700
Alumina AL88I 2.59 23.8 8.0 4.2 1700
Alumina AL90C 2.9 18.0 7.7 4.0 1750
Alumina AL92C 2.95 24.8 8.0 4.2 1750
Alumina AL97C 3.1 19.6 8.0 4.1 1800
Chrome Alumina CA93I 3.05 23.0 8.2 3.4 1800
Chrome Alumina CA84I 2.85 20.0 7.6 3.4 1730
Chrome Alumina CA94I 3.10 21.5 8.2 3.4 1800
Chrome Alumina CA93C 3.14 19.3 8.2 3.0 1750
Magnesia MG88I 2.83 17.0 14.5 2.4 1700
Magnesia MG95I 2.95 15.0 13.0 2.5 1750
Mullite ML72I 2.32 21.5 4.2 1.8 1700
Zircon ZN66I 3.60 21.9 4.6 2.1 1750
Zirconia ZC93I 4.35 20.0 8.4 1.5 1850
Zirconia ZC95I 4.50 18.5 8.5 1.6 1850
Zirconia ZC96I 4.50 18.5 8.5 1.6 1850
Sillimanite SL58C 2.42 18.7 4.5 1.6 1650
Sillimanite SL63C 2.32 22.0 4.5 1.6 1650

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