Plaster and casting refractory clay mixes

Refractory Plastic (low expansion)

Total:124.00

Notes

*This rounds off the L4404A recipe (not low expansion), it switches from silica to Pyrophylite and adds more grog.

Our first testing was for use as calciners that must withstand quartz inversion pass-thru multiple times. Then kiln shelves and kiln posts.

Both silica and alumina have poor thermal shock properties whereas Pyrophylite has good properties (assuming we are not firing to temperatures higher that 2000F). That was confirmed in that a calciner withstood use to cone 2 but failed with a hairline crack to cone 6.

Pictures

L4404C Plastic Refractory fired bars Vs fireclays

L4404C Plastic Refractory calciner fired to cone 2

Repeat fast bisque did not crack it.

L4404C calciner fast fired to cone 6 (from cone 2)

It did survive a second firing to 1850F but this crack on the third likely happened because the base did not heat like the walls. These cracks are only on the bottom, they did not go up the walls.

Untitled

Refractory Casting (low expansion)

Total:99.00

Notes

*We are planning on using this to make large calcining vessels for roasting Alberta Slip and Ravenscrag Slip. We have already used a plastic version of this with good success to make the calciners (it employs Tile #6 Kaolin instead of nonplastic Kaopaque).

I wanted to put in Kyanite but in realized there is no way it will stay in suspension (it is too heavy).

This powder does not mix with water easily. First test mix:
4000:1600:25
Powder:Water:Darvan

Pictures

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Refractory Casting (low expansion)" id="252180" key="psTN78Da" date="2024-05-08" codenum="L4404D"> <recipelines> <recipeline material="Kaopaque Kaolin" amount="33.000" tolerance=""/> <recipeline material="M23 Ball Clay" amount="33.000" tolerance=""/> <recipeline material="Pyrophylite" amount="33.000" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2021-02-12, Modified: 2024-05-08 19:53:26

Alumina Lining for Crucibles

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.

Zircon Lining for Crucibles

Total:100.00

Notes

*We use this as a lining in crucibles made using refractory L4404A casting slip. It stays more powdery than alumina and resists wetting by melting glasses and frits.

This is applied as an inner layer after slip draining. The thicker layers leave it in the mold for a while.

Pictures

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Zircon Lining for Crucibles" id="252893" key="3sbn4rJR" date="2024-03-03" codenum="L3693E1"> <recipelines> <recipeline material="Zircon" amount="90.000" tolerance=""/> <recipeline material="Kaolin" amount="10.000" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2017-05-05, Modified: 2024-03-03 02:31:55

Refractory Casting Slip

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.