Crucibles & Slip Cast Items

Our slip casting process produces dense crucibles with fine grained microstructure and less than 1% open porosity.

INTRO: Magnesium Oxide Crucibles and shapes were only available to the U.S. Government for several decades following their development at Los Alamos National Lab in support of the Manhattan Project in the early 1940’s. Commercial availability began in the late 1970’s, and TATEHO OZARK has met all industrial requirements since our founding in 1986. We have many sizes available from stock. Discounts are quoted for quantity orders on request. Please contact us for prices.

FLAT BOTTOMED CRUCIBLES

Item NameDiameter (in)Height (in)Solid Volume (cc)Weight (gms)Interior Vol. (cc)
SC024020.240.200.070.30.05
SC040080.400.790.940.5
SC050100.501.00281
SC071160.711.575185
SC075100.751.003134
SC100101.001.004197
SC100121.001.255239
SC100301.003.00135124
SC125121.251.2583615
SC125201.252.00135425
SC125251.252.50176631
SC125601.256.004115077
SC150201.502.00166738
SC150301.503.00259759
SC175251.752.50249970
SC175351.753.503413499
SC200202.002.00229775
SC200352.003.5039157135
SC200502.005.0057217195
SC200602.006.0068257234
SC225352.253.5044180176
SC250302.503.0042179189
SC250552.505.5079306354
SC275352.753.5063265264
SC300303.003.0059259272
SC300403.004.0080330368
SC300573.005.75116455534
SC350603.506.00142566782
SC400454.004.50121518777
SC400604.006.001636621044
SC450604.506.001847611343
SC500505.005.001707431394
SC500805.008.0027511052254

ROUND TRAYS

Item NameDiameterHeightSolid Volume (cc)Weight (gms)Interior Vol. (cc)
SR10051.000.502113
SR20052.000.5043715
SR20102.001.00105735
SR30053.000.5078234
SR30103.001.001811782
SR40054.000.501013464
SR40104.001.0024182153
SR60106.001.0040395349
SR60126.001.2552437453

RECTANGULAR TRAYS

Item NameWidthLengthHeightSolid Volume (cc)Weight (gms)
ST1040051.004.000.5012.844
ST1060051.006.000.5018.765
ST2020052.002.000.5013.547
ST2030052.003.000.5021.674
ST2040052.004.000.5027.896
ST2540052.504.000.5033.2115
ST2540102.504.001.0047.5164
ST2560102.506.001.0066.8231
ST3060103.006.001.0075.7261
ST3560103.506.001.0095.5329
ST4040104.004.001.0067.2232
ST4060104.006.001.00105.6364

FLANGED LIDS

Item NameDiameterHeightSolid Volume (cc)Weight (gms)
SF1001.000.2310
SF1251.250.2414
SF1501.500.2621
SF2002.000.21035
SF2502.500.21655
SF3003.000.22379
SF4004.000.241141
SF4504.500.252179
SF5005.000.264221
SF7007.000.2126435

Standard High Density MgO Cast Shapes

These components have been selected as standard sizes for the convenience of our customers. Other sizes and shapes may be in open stock, and any requirements will be quoted on a custom basis. Delivery may not be from open stock.  Please contact us for lead times. All dimensions are outside dimensions and may vary +/- 5%. Volumes are in cc's and are only approximate because the wall thickness may vary considerably. Nominal wall is lesser of 5% of diameter or .125 inch. Some warping and sidewall distortion is normal for MgO, especially rectangular shapes. Nominally flat surfaces may be slightly convex or concave. All tray Heights are hand finished and may vary by 25%.

Advantages

  • Better chemical resistance than alumina in certain applications
  • Proven alternative to alumina in testing of slags
  • Use temperatures up to +2200  C in specific environments

Uses

  • Molten Metal Alloy Processing
    • Viable alternative to Al2O3 based ceramics
    • Compatible with nickel-based alloys
    • Proven performance with plutonium/uranium refining
  • High Temp Ceramic Superconductor Materials
    • Resistant to attack
    • Non-contaminating to 1, 2, 3 materials
    • Perovskite structure compatibility
  • Piezoelectric Materials Processing
    • Resistant to lead based materials
    • Helps maintain lead content in PLZT

Design Guides

ABOUT Slip Casting Every part must begin with an aluminum master pattern (positive) of the same shape, but enlarged dimensionally to compensate for process shrinkage.  Plaster molds (negatives) are pulled from the master.  Multiple molds are needed for each casting run. Many patterns and molds are available.  Custom shapes will require set-up charges and sufficient lead time for mold master and mold production.  The green parts require drying time, trimming to length, and firing to produce the finished product. SHAPE High Quality MgO Ceramic shapes are made by slip casting. Slip casting is suitable for production of hollow shapes with uniform wall thickness and an opening to the interior. This is ideal for shapes such as crucibles, trays, boats, etc. There should be no re-entrant angles along the longitudinal cross section of the part (such as Ell-shapes, Crosses, etc.). Slip casting will produce a variety of shapes as indicated above. Surface finish does not approximate that of machined surfaces. Nominally flat surfaces, such as lids, crucible and tray bottoms, and plates will be concave or convex after firing. If precision dimensions or flat surfaces are required, additional wet diamond machining is required, and many limitations apply. SIZE The normal fabrication range is for diameters less than 6 inches and lengths less than 12 inches. Larger parts can be made upon request, at some sacrifice in cost and dimensional control. Please inquire for further information. The nominal wall thickness for most shapes is 0.125” (or 3mm), and the maximum thickness available is limited to 0.16 inch (4mm). The wall thickness must be uniform throughout the part. TOLERANCES Unless tighter tolerances are specified, dimensional tolerances for diameters, heights, and lateral dimensions are 0.125 inch or 5%, whichever is less. The nominal wall thickness for standard crucibles varies with the crucible diameter from 0.10" to 0.16".  Minimum wall thickness available is approximately 0.060" on small crucibles.  Maximum wall thickness that can be produced is approximately 0.20".  These tolerances apply to nominal dimensions only, and do not apply to out of round conditions or distortions. Please consult us if dimensional constraints are important so that the tolerances and inspection methods may be clarified. Other visual inspection criteria will be supplied on request. DENSITY Slip cast crucibles exhibit fine grained microstructure and low open porosity. The bulk density is typically a minimum of 3.40 - 3.45 gm/cc, or 92-94% of theoretical.  Open porosity is less than 1%. The high density body contains 2% yttrium oxide (Y2O3) content as a sintering aid in direct substitution for MgO content. PURITY All slip cast products are manufactured from high purity fused magnesium oxide grain. A direct substitution of up to 2% Y2O3 is made at the expense of MgO. The Y2O3 promotes sintering and is totally inert and equivalent to MgO in all applications. TYPICAL ANALYSIS BELOW:
MgO + Y2O398.5%
CaO0.5%
SiO20.1%
Al2O30.55%
Fe2O30.06%
B2O3<0.002%
STRENGTH Fired MgO parts have reasonably good mechanical strength, but are susceptible to thermal shock. Uniform heating and cooling conditions are necessary to avoid thermal shock damage.  Maximum heating and cooling rates of 200 C per hour are recommended and thermal gradients should be avoided.  If being used at temperatures above about 1200 C, creep strength limitations should also be provided for. Please consult us with any questions concerning physical properties.

 

INTRO:

TATEHO OZARK specializes in magnesia ceramics, but many of our customers also use alumina ceramics for various applications.  TATEHO OZARK manufactures 99.5% alumina crucibles and trays in the same sizes and price range as our magnesia products.

What are the Specs? A quick synopsis:

Purity: 99.5%  minimum Alumina

Density:  > 3.7 gm/cc minimum, typically 3.85 gm/cc.  (Theoretical density for Al2O3 is 3.98 gm/cc)

Porosity:  Typically 4%, less than 1% open porosity.

Dimensions:  Most of the same limitations as for MgO, the normal fabrication range is for diameters less than 5 inches and lengths less than 8 inches.

Wall thickness: As with MgO, the nominal wall thickness for most shapes is 0.125” (or 3mm), and the maximum thickness available is about 0.2 inch (4mm) and the minimum is about 0.08 inch (2mm).

Other:  Surface finish may vary, but is usually smooth.  Surface is not usually “vitrified”.

Design Guides

The design guides are common to both MgO and Al2O3 slip cast bodies which are made by the same production processes.

ABOUT Slip Casting
Every part must begin with an aluminum master pattern (positive) of the same shape, but enlarged dimensionally to compensate for process shrinkage.  Plaster molds (negatives) are pulled from the master.  Multiple molds are needed for each casting run.

Many patterns and molds are available.  Custom shapes will require set-up charges and sufficient lead time for mold master and mold production.  The green parts require drying time, trimming to length, and firing to produce the finished product.

SHAPE
High quality alumina shapes are made by slip casting. Slip casting is suitable for production of hollow shapes with uniform wall thickness and an opening to the interior. This is ideal for shapes such as crucibles, trays, boats, etc. There should be no re-entrant angles along the longitudinal cross section of the part (such as Ell-shapes, Crosses, etc.).

Slip casting will produce a variety of shapes as indicated above. Surface finish does not approximate that of machined surfaces. Nominally flat surfaces, such as lids, crucible and tray bottoms, and plates will be concave or convex after firing. If precision dimensions or flat surfaces are required, additional wet diamond machining is required, and many limitations apply.

SIZE
The normal fabrication range is for diameters less than 5 inches and lengths less than 8 inches. Larger parts can be made upon request, at some sacrifice in cost and dimensional control. Please inquire for further information.

The nominal wall thickness for most shapes is 0.125” (or 3mm), and the maximum thickness available is limited to 0.2 inch (4mm). The wall thickness must be uniform throughout the part.

TOLERANCES
Unless tighter tolerances are specified, dimensional tolerances for diameters, heights, and lateral dimensions are 0.125 inch or 5%, whichever is less. These tolerances apply to nominal dimensions only, and do not apply to out of round conditions or distortions. Please consult us if dimensional constraints are important so that the tolerances and inspection methods may be clarified. Other visual inspection criteria will be supplied on request.

DENSITY
Slip cast crucibles exhibit fine grained microstructure and low open porosity. The bulk density of alumina is typically a minimum of 3.7 gm/cc, or 94% of theoretical.  Open porosity is less than 1%.

PURITY
All slip cast alumina products are manufactured from high purity calcined aluminum oxide.
Typical Analysis:

Al2O399.60%
CaO0.04%
SiO20.02%
MgO0.06%
Fe2O30.04%
Na2O0.08%

STRENGTH
Fired alumina parts have reasonably good mechanical strength and reasonably good thermal shock resistance.  However, the thin walls limit the mechanical strength and charge weight the crucibles can tolerate.  Please consult us with any questions concerning physical properties.