Ridgidizers for ceramic/mineral wools?

[smartliketruck]

I'd like to find a recipe for an effective rigidizer for ceramic/mineral wools such as kaowool, roxul, rockwool etc. that would be easy for others to replicate. Since the amount of rigidizer needed would not be much should be pretty affordable.

Off the top of my head raw materials I've collected over the past few years and have on hand are

Pioneer kaolin - pottery supply

EPK kaolin — pottery supply

Bentonite - Wyoming gel - from oil and gas drilling

Glowmax LL - calcined kaolin

Titanium dioxide - pottery supply

Zircopax - Zircon - Zirconium Silicate - pottery supply

Fly Ash type F - concrete industry

Fumed silica - from plastics industry

Densified  silica fume - from concrete industry

Silica gel dessicant - crystal cat litter

Magnesium oxide - livestock feed supplement

Diatomacious Earth - feed grade off white in color

Ecogrip - green colored zeolite granules

Graphite powder - from oil and gas drilling

SAPP - sodium acid pyrophosphate - from oil and gas drilling

TKPP -tetrapotassium pyrophosphate - from oil and gas drilling

TriSodium Phosphate - hardware store paint department

Xanthan gum - cooking supply and oil and gas drilling

Sodium Hydroxide - lye - caustic soda - soap making supply

Potassium Hydroxide - caustic potash - soap making supply

Hydrogen Peroxide 3% - regular drugstore disinfectant

Hydrogen Peroxide 10% - non-chlorine bleach

Phosphoric Acid 55% - hydroponics supply

Citric acid - home brewing supply

Malic acid - cooking/candy supply

Tartaric acid - home brewing supply

5% Acetic acid - standard white vinegar

10% Acetic acid - cleaning vinegar

In another thread Karl suggested  Glowmax and phosphoric acid so I'll try that route first.

If you have access to some of the same materials as me and want to try rigidizing perhaps we of the forum can hash it out here.

[smartliketruck]

This thread is to carry on from another thread

Feb 23, 2020 10:49:03 GMT -8 @karl said:

Feb 23, 2020 8:57:25 GMT -8 smartliketruck said:

Have you found a satisfactory mixture for a ridgidizer yet Gadget?

I just picked up a kg of fumed silica for the steep price of $70 Cdn so I'd rather not use much with recursive testing.

One can perform tests with less than one g.

One should not use something just because some forge sites do.

I would rather use

Kaolin - Glomax LL (Calcined) with phosphoric acid because it will not swell as much as with lye

or

Grog - 200 Mulcoa with some lye or waterglass, can be made very runny.

A small amount of citric acid added to phosphoric acid makes it much more aggressive to ordinary clays especially red ones.

All a lot cheaper.

I was just at Plainsman clays and I'm kicking myself for not getting some Mulcoa grog, Feldspar and Tabular Alumina. But I was happy to pick up the Zircopax and Titanium dioxide to see if increasing IR reflectivity substantial benefits can be realized.

[Deleted]

One could test a thin slip of Kansas City #1.
Should work pretty well.

[smartliketruck]

Feb 25, 2020 10:04:41 GMT -8 @karl said:

One could test a thin slip of Kansas City #1.
Should work pretty well.

Since I don't have the MKP and haven't found it at reasonable cost locally I'll have to look into using my other phosphate salts. Since TSP is alkaline and available in most hardware and paint stores here in Canada and I'm guessing in the USA also, I might go that route first.

[Deleted]

Feb 25, 2020 20:33:18 GMT -8 smartliketruck said:

Feb 25, 2020 10:04:41 GMT -8 @karl said:

One could test a thin slip of Kansas City #1.
Should work pretty well.

Since I don't have the MKP and haven't found it at reasonable cost locally I'll have to look into using my other phosphate salts. Since TSP is alkaline and available in most hardware and paint stores here in Canada and I'm guessing in the USA also, I might go that route first.

TSP should work as well and is actually easier to use because it must not first be made more alkaline.

At farmer shops fertilizers are usualy lower priced than cleaners at hardware and paint stores.

[smartliketruck]

Feb 26, 2020 9:12:12 GMT -8 @karl said:

TSP should work as well and is actually easier to use because it must not first be made more alkaline.°
At farmer shops fertilizers are usualy lower priced than cleaners at hardware and paint stores.

Where I live, I was only able to find straight MKP in 20kg sacks (IIRC), which would be enough for 248 liters of uncured Kansas City #1

I did find a small $15-$20 CAD 130g jar of Grotek Monster Bloom which is 0-50-30, the 2009 MSDS shows it to be MKP and 1% or less magnesium sulphate, it also has a purple colorant added. This would make about 1.6 liters of KC#1 which would fit the bill of someone thinning it for a ridgidizer.

The TSP route has the disadvantage of a lower melting point due to sodium versus potassium. If the predominant result is nepheline, it will transition to carnagieite at 1254°C and then melting at 1526°C versus kalsilite inverting around 1540°C and melting about the 1734°C mark.(Temperatures taken from Davidovits book)

Not sure how much of an effect the transition or inversion effects long term stability of the refractory.

I'm doubtful I'll see over 1200°C with any regularity so the TSP should work fine.

I'm now going to head outside to dig out the materials and equipment to give this a try

[smartliketruck]

Mixed up a small batch last night using

donkey32.proboards.com/thread/3283/geopolymer-code-named-kansas-city

I used TSP as a direct replacement by weight for the the MKP + KOH. I was surprised at how low the viscosity was without the chopped rockwool fibers, I guess this explains why Sheldon had what seemed to me to be a large shrinkage rate of 10%.

I did not thin the mixture further this time around, just dunked a few pieces of ceramic fiber blanket and roxul and am currently curing at 65°C.

If I have time tonight I'll mix another small batch and thin it considerably more as the current mixture would be better suited to more of a paper mache style of application to a plug/mold.

[Deleted]

Shrinkage can be lowered by a higher amount of accelerator.
Cement is convinient, but sulfur free accelerators like quicklime or many years old slacked lime would be better.

[smartliketruck]

I mixed three small batches of KC#1 with TSP last night, one batch just regular KC#1 + TSP, one substituting 5 grams of hydrated(builders) lime for 5 grams of portland, one substituting 50 grams of zeolite for 50 grams of kaolin.

After 11 hours at 75°C in sealed containers, the two modified batches are firmer than the regular but still not even close to firm enough to de-mold.

I upped the temperature to 85°C and will see what they are like tonight.

[Deleted]

Use as a rigidizer is something completely different.

[smartliketruck]

Mar 1, 2020 10:42:05 GMT -8 @karl said:

Use as a rigidizer is something completely different.

I should clarify, I'm testing both as a rigidizer and also as a castable.

I thinned 100g of each mixture down with 50g additional water to rigidize 15g strips of ceramic fiber blanket, those will be dried like one would expect to use a rigidizer.

I mixed the remainder that was not thinned with 15g of chopped roxul fibers, that is what is currently curing at 85°C.

[james04]

Mar 1, 2020 16:55:01 GMT -8 smartliketruck said:

Mar 1, 2020 10:42:05 GMT -8 @karl said:

Use as a rigidizer is something completely different.

I should clarify, I'm testing both as a rigidizer and also as a castable.

I thinned 100g of each mixture down with 50g additional water to rigidize 15g strips of ceramic fiber blanket, those will be dried like one would expect to use a rigidizer.

I mixed the remainder that was not thinned with 15g of chopped roxul fibers, that is what is currently curing at 85°C.

How did this turn out? Did you settle on a formula for both a rigidizer and castable?

[gadget]

Smartliketruck,

Whats your end goal with rigidizing? I've done lots of research, mostly from forging forums. Here is what I have learned;

the fumed silica is a nano particle and when applied wet it wicks and coats the fibers, also binds them to each other where they touch each other. Fumed silica is used with a slurry of loose fibers to form and mold ceramic fiber shapes and boards. Ive used it to form a thin ceramic fiber blanket with success. 

Its also used to firm up fibers BEFORE applying a face coat to ceramic fiber blankets and sometimes board. This greatly extends the life of the ceramic fibers. This is something we wood heaters should look into......

Its also used for those concerned about breathing in loose fibers. This could be handy with say a door area where the fiber could be made air borne. It could help keep the fibers together more but not 100%.

Whats your goal with rigidizing?

[Deleted]

gadget
Fumed Silica is a notoriously difficult powder to disperse.
Complete dispersion requires a degree of shear hardly achieved by a household mixer.

[gadget]

Mar 15, 2021 3:35:52 GMT -8 @karl said:

gadget
Fumed Silica is a notoriously difficult powder to disperse.
Complete dispersion requires a degree of shear hardly achieved by a household mixer.

Hey Karl,

I don't know to much about the mixing issue you mention. I know it worked great for me, at least that is assuming I got maximum results. Maybe it could have worked better? I just shaked it in a jar. I know lots of hobby folk use it with out problems. I know its the main way for molding ceramic fiber shapes when they mix their slurries.

I keep hoping to need a custom ceramic fiber shape some day so I can try my hands on a slurry mold but to many other pressing projects right now.