British-made since 1976

Low scrap, guaranteed

Crucibles to 1,000 kg

Alumina crucibles for air and vacuum melting

The workhorse of the range. High purity alumina handles both air and vacuum induction melting, with the thermal shock resistance and smooth, non-wetting surface the investment caster relies on.

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Key benefits

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Thermal shock resistance

Excellent thermal shock resistance through the severe thermal heating cycle, in both air and vacuum induction furnaces.

Smooth, non-wetting finish

A smooth surface finish with the non-wetting characteristics required by the investment casting foundry.

Minimal metal erosion

Metal erosion is reduced to a minimum, for clean metal with minimum casting inclusions, guaranteed.

Reusable over multiple pours

Low thermal expansion properties enable the foundry to reuse the crucible for multiple pours.

High purity alumina, 97% Al2O3

Produced from a 97% high purity alumina mix with a uniform, homogeneous refractory body, specifically designed with low porosity and high density.

Purity: 97% Al2O3
Max service temperature: 1800°C
Capacity range: 8 to 265 kg pressed, vibro cast to 1,000 kg

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Applications and alloys

The workhorse choice for air and vacuum melting induction furnaces, compatible with most high temperature alloys.

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Furnaces: Air and vacuum induction melting
Alloys: Most high temperature alloys
Above 1800°C: See the zirconia range, to 2200°C

Technical data

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Isopressed round bottomed crucibles

Drg No	ID	OD	IL	OL	Full capacity, kg of steel
624	97	119	270	290	12.6
613	102	128	254	272	13.1
621	102	128	305	325	15.8
620	108	127	199	210	11.5
655	110	125	210	230	12.6
629	116	137	275	305	18.5
601	118	137	265	290	18.3
605	120	144	229	250	16.4
612	120	138	250	275	18
673	120	140	305	318	22
643	120	140	305	330	21.8
656	120	137	365	390	26.2
889	125	150	230	255	18
632	125	150	250	270	19.5
644	125	150	305	330	23.7
636	125	150	350	370	27.2
833	131	148	315	335	26.9
614	140	165	305	330	30
610	140	165	355	375	35
842	143	173	274	291	28
829	143	173	455	500	46
861	150	170	380	400	42
885	150	170	420	440	47
858	152	175	305	330	35
813	158	190	380	410	47
825	200	230	470	500	100
802	228	260	430	470	111
801	245	278	440	465	132

All dimensions in mm. Drg No: drawing number. ID: inside diameter. OD: outside diameter. IL: inside length. OL: overall length.

Isopressed flat bottomed crucibles

Drg No	ID	OD	IL	OL	Full capacity, kg of steel
677	95	116	190	220	8.7
603	95	120	181	221	8.1
604	95	120	241	275	10.8
684	95	115	305	330	13.7
875	95	115	356	370	16
843	102	128	319	332	16
688	106	125	205	220	14.3
873	110	135	205	230	15
855	118	141	233	252	16
840	127	148	175	200	14
839	127	148	249	274	20
660	127	150	247	268	19.8
678	127	153	356	380	28.7
639	130	150	268	285	22.5
659	136	165	290	315	26.9
611	140	165	290	315	28.3
851	140	165	317	341	30
641	140	165	380	405	37
828	143	175	300	325	31
859	152	178	304	330	35
883	158	190	300	330	37
821	170	203	395	425	60
882	175	203	300	330	43
848	178	212	410	435	65
837	178	212	470	500	74
827	206	242	456	483	96
811	245	278	465	500	140
831	258	305	431	458	140
835	280	320	435	465	170
895	300	340	590	650	265

All dimensions in mm. Drg No: drawing number. ID: inside diameter. OD: outside diameter. IL: inside length. OL: overall length.

Chemical analysis

Component	% by weight
Al2O3	97.00
Na2O	0.28
Fe2O3	0.03
SiO2	0.88
CaO	0.03
TiO2	0.01
MgO	1.65
K2O	0.12

Typical chemical analysis, percentage by weight.

Physical properties

Property	Value
Apparent Porosity	20%
Bulk Density	3000 kg/m³

Recommended backing mix

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MIPEX Dry Crucible Backing Mix

MIPEX is specifically designed for use with high alumina crucibles. Its high thermal expansion grips the crucible throughout the temperature range, then forms a spinel that keeps supporting the body as it cools.

Specification Magnesia spinel, MIL-12

Other crucibles

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Super Zirconia Crucibles

Magnesia stabilised for the most demanding vacuum work. Low thermal expansion means one crucible survives pour after pour of superalloy, the reason aerospace casters specify it.

Lime Stabilised Zirconia Crucibles

Trusted with platinum group metals at up to 2200°C. Lime stabilisation prevents volume changes, so the body resists spalling and erosion through the severest heating cycles.

Chrome Alumina Crucibles

A small addition of chrome oxide gives the alumina body its resistance to slag attack, extending crucible life in the air melting commercial foundry.

Magnesia Crucibles

Lighter than zirconia and preferred by some customers for X-ray analysis. The magnesia body carries lower running costs than stabilised zirconia.

Frequently asked questions

Magna supplies alumina crucibles against drawing numbers or to new dimensions. Send your alloy, furnace type and melt size with an enquiry for a specification.

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What temperature can an alumina crucible withstand?

Magna alumina crucibles have a maximum service temperature of 1800°C, suited to most high temperature alloys in air and vacuum melting induction furnaces. For platinum group metals, lime stabilised zirconia serves up to 2200°C.

Is alumina suitable for vacuum induction melting?

What purity is a Magna alumina crucible?

Which backing mix should be used with alumina crucibles?

What sizes are alumina crucibles available in?