Casting crucibles with an alumina oxide liner

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Used for melting frit batches to create ingots that are easily separated from the container


Refractory Casting Slip

Code #

L4404A

Materials Amt
Pioneer Kaolin 35.000 24.61%
*KT1-4 Ball Clay 35.000 24.61%
Silica 30.000 21.09%
Water 41.580 29.24%
*Darvan #7 0.640 0.45%

Total:142.22

Notes

*This is used to make melt flow testers. It is very refractory, still highly porous even at cone 10. We are able to cast pieces of very thin walls and they do not warp in firing even at cone 6.

This has excellent casting properties and releases from molds quickly. It ages well without change to the rheology.

We make 5000g batches and get about 1.78 SG from this mix. Aging may require the addition of a little more Darvan or water.

Pictures

L4404A without and with L3693E liner

These frit ingots have melted to cone 04 and slow cooled. We used cast crucibles made from L4404A refractory slip. The front one has an alumina oxide liner of L3693E. Without the liner, the ingot in the back is inseparable from the body. But with the liner (front), it easily breaks away. The alumina has remained as a powder and can be easily cleaned off the ingot leaving almost no residue. Frit manufacturers crash cool frit batches by quenching them in water, this one was slow-cooled, we are hoping that will make the difference to enable it to pass a lead leaching test.

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Refractory Casting Slip" id="194791" key="ZCm2c8sT" date="2024-03-03" codenum="L4404A"> <recipelines> <recipeline material="Pioneer Kaolin" amount="35.000" tolerance=""/> <recipeline material="KT1-4 Ball Clay" amount="35.000" tolerance=""/> <recipeline material="Silica" amount="30.000" tolerance=""/> <recipeline material="Water" amount="41.580" tolerance=""/> <recipeline material="Darvan #7" amount="0.640" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2021-02-12, Modified: 2024-03-03 01:10:36

Alumina Lining for Crucibles

Code #

L3693E

Materials Amt
Calcined Alumina 200.000 96.15%
VeeGum 8.000 3.85%

Total:208.00

Notes

*We have not had good luck casting ware using pure alumina. However this project is to assess whether an alumina slurry could be applied, by pouring, as a fine layer inside a slip-cast refractory crucible.

First, we tried regular bentonite, 4%. This dewatered too slowly and did not bond well enough. Veegum is much better (and more potent). A lot is needed to make a slurry that works well. Veegum is also a flux

Recipe: 1000 powder, 700 water.
Deflocculated well but gels and needs to be shaken to reliquify. However, this is not really an issue if we just pour it into a freshly cast vessel and pour it out right away.

This is only useful on highly refractory bodies (ones having very low firing shrinkage), otherwise it will flake off during firing.

Pictures

Cone 10R bars of Alumina Crucible bodies

L4404A without and with L3693E liner

These frit ingots have melted to cone 04 and slow cooled. We used cast crucibles made from L4404A refractory slip. The front one has an alumina oxide liner of L3693E. Without the liner, the ingot in the back is inseparable from the body. But with the liner (front), it easily breaks away. The alumina has remained as a powder and can be easily cleaned off the ingot leaving almost no residue. Frit manufacturers crash cool frit batches by quenching them in water, this one was slow-cooled, we are hoping that will make the difference to enable it to pass a lead leaching test.

Testdata

SHAB - Shrinkage/Absorption

DLEN FLEN FWT BWT CONE DSHR FSHR ABS
195.6394.7350.9560.3610R4.4%0.9%18.5%

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Alumina Lining for Crucibles" id="111990" key="hWko9Zen" date="2024-03-03" codenum="L3693E"> <recipelines> <recipeline material="Calcined Alumina" amount="200.000" tolerance=""/> <recipeline material="VeeGum" amount="8.000" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2017-05-05, Modified: 2024-03-03 01:16:34