Refractory Crucibles for Induction Melting

Shop Refractory Crucibles

Almath produces a range of refractory crucibles ideally suited for induction melting, whether this is air-melt or vacuum induction melting (VIM). These crucibles are used for demanding applications such as melting superalloys for investment casting and melting precious metals such as platinum and palladium. The requirements for these crucibles are particularly demanding as aerospace and medical components are often made.

In precious metals the control of dissolved contaminants and inclusions is particularly important to maintain the purity of the material and optimise yield. Almath can offer a range of crucible materials depending on the material to be induction melted. Our range of crucibles include:

Alumina
Magnesium Oxide
Zirconia

Standard Refractory Crucible Materials

Our refractory crucibles utilise a controlled porosity to retard the crack growth that occurs during thermal shock. Induction melting is particularly aggressive as the temperature of the metal rises rapidly and heats the crucible from the centre outwards. This process makes the thermal shock conditions highly demanding, particularly when metals are being heated to nearly 2000°C. The design of crucibles porosity means that crack growth can be prevented by blunting the crack tip and dissipating its growth energy.

Almath have produced high purity crucibles for three decades. We know how important preventing contamination is for our customers, and we apply the same mindset to our refractory crucibles to minimise the risk of inclusions.

The choice of material is dependant upon the application. Below are some descriptions to help select the best material for you application.

Alumina - good general purpose crucible materials with good resistance to acidic and basic slags and compounds. It can be used up to around 1700°C and is suitable for a wide range of alloys.
Magnesia – excellent resistance to basic slags and alkali compounds, it has a similar peak temperature to alumina. Used for vacuum melting of Ni, Co and Fe.
Zirconia – excellent resistance to acidic slags & compounds. Can be used at temperature over 2000°C, and is particularly suitable for precious metals, including the platinum group metals and superalloys.

Material	Composition	Apparent Porosity (%)
Lime Stabilised Zirconia	3.75% CaO	24%, 19.5%, 16%, 6.5%
Magnesia Stabilised Zirconia	3.5% MgO	21%, 18%
Alumina	97.5% Alumina	21%
Magnesium Oxide	95% MgO	15%

Almath is also able to develop customer specific materials, please contact us to discuss your requirements.

Isostatically Pressed Crucibles

Almath manufactures its refractory crucibles by isostatic pressing. This process has been selected because it offers a range of benefits, including:

Uniform density across the whole crucible to reduce thermal stresses and achieve consistent properties in each crucible
Controlled porosity to improve thermal shock resistance
Smooth internal finish to minimise the risk of inclusions
A wide range of sizes can be manufactured and in low to high volume

Standard Porous Crucible Sizes

Our crucibles are available in standard sizes, if you do not see the ideal crucible size available, please contact us and we are able to manufacture a crucible to your specific sizes.

Outer Diameter (mm)	Wall Thickness (mm)	Inner Diameter (mm)	Outer Height (mm)	Inner Height (mm)
38	7.5	23	57	46
38	7.5	23	76	65
38	7.5	23	95	84
54	8.5	37	80	67
54	8.5	37	108	95
54	8.5	37	135	122
70	7.5	55	105	94
70	7.5	55	140	129
70	10	50	175	160
86	11	64	150	134
86	10	64	172	157
86	10	64	215	200
100	10	80	150	135
100	10	80	200	185
100	10	80	250	235
130	10	110	195	180
130	10	110	260	245
130	12.5	105	325	306
160	10	140	240	225
160	12.5	135	320	301
160	12.5	135	340	321
180	12.5	155	280	261
180	12.5	155	340	321
180	15	150	375	353
210	15	180	320	298
210	15	180	375	353

Browse our range of refractory crucibles.

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