Jump to content
I Forge Iron

Recommended Posts

  • Replies 1.6k
  • Created
  • Last Reply

Top Posters In This Topic

The person who built this welded a large hinge on each side. I drove the pin out and I have to admit, it really makes working on it easy. 

I test fitted it once the ITC 100 was dry and there were a couple gaps where a hint of light could be seen where the top & bottom meet. So I cut a piece of Kaowool to use as a gasket.

Soaked it in rigidizer and assembled the top & bottom and left it to dry in place.

Probably a bit inefficient splitting the tank that way but I have to say it certainly is convenient.

997BF9DF-F8E0-482F-B77B-E53137608B65.jpeg

DC56B2D7-68B6-4854-9A4E-0B8B90D07499.jpeg

Link to post
Share on other sites

Zirconia

Zirconia (zirconium oxide) is, I believe, the main ingredient in ITC 100. All materials radiate energy when heated; some better than others. Zirconia is one of the best refractory materials for re-radiation; and re-radiation is what all high temperature "heat shields" are all about. BUT  what percentage of energy gets radiates back out of a material also depends on how small the particles being heated are. Zirconia can re-radiate as much as 93% of incoming energy, or as little as 67%, according to information I've run across online.

 

with that in mind, I separated some ITC 100, into colloidal and crude particles by swirling some some of the muddy mixture in a water glass. The crude particulate fell out of solution, leaving only the colloidal particles dissolved. After painting this solution on the inner surfaces of my forge,  Its temperature increased from orange to lemon yellow incandescence; this appears to bare out the statement that re-radiation increases as particulate size decreases.

Why should that be so? While these little specks of zirconium oxide are re-radiating their heat back outward, they are also conducting heat to other particles, and eventually out of the forge. The smaller the particle the greater the surface area, by percentage, to radiate. The larger the particle the smaller the surface area, by percentage, and the greater the internal area to conduct heat.

Zircinia isn't as cheap as alumina, but is it far from exotic. While colloidal grade (extremely fine) powder isn't cheap, the cheaper grade zirconia powders used as refractories contain a large percentage of colloidal particles in them, and they are easily separated by swirling some powder in water.

Link to post
Share on other sites

Phosphoric acid

Phosphoric acid can be purchased as crystals and dissolved in water, where it remains is solution, just like colloidal particles of zirconium oxide. When this mixture is painted on the inside of your forge, and allowed to dry, then heated, the  phosphoric acid  polymerizes; thereafter it forms a kind of glass at room temperatures, and a sticky paste while incandescent. Becuase it isn't a solid above 940 F. Thus, the change in crystal size that zirconium oxide goes through with every heating cycles doesn't break down the  phosphoric acid that olds the zirconia on all those vertical and overhead surfaces; and it cheap too :D

Link to post
Share on other sites

Put some of the acid in water, and then dissolve the zirconia powder into the mix. All the acid is for is to keep the zirconia particles in place. The mixture creates a coating on forge surfaces that is about as thin as a single coat of paint. The natural question to ask next is how much of each? I don't know. I do know that ITC 100 is a very thick mud; which means that little liquid content is present. I also think that a very wide range of percentages will work just fine.

So, probably your idea would work just fine :)

On the other hand, I used a lot more water to separate the colloidal content of zirconia from crude particulates, and painted the thin solution in my forge, and that worked just fine too. I think it is similar to silica rigidizer in that a very wide range of percentages will work out.

Link to post
Share on other sites

I just got back to this thread, chores and. . . stuff. So the phosphoric acid acts as cement sticking zirconia particles together. I was driving down the road after posting my last question when I realized I'd forgotten to ask what % is good. I bought the acid at a scientific supply and it's something like 99.7%+ pure. I derust steel with a 20%-30% dilution with a splash of Jetdry as surfacant. 

So, how about adding a couple few % phosphoric acid to a zircopax bentonite mix? Better, worse, waste of chemicals? 

Frosty The Lucky.

Link to post
Share on other sites

The phosphoric acid acts like cement (actually a form of glass) when the forge is called cold, and like mastic above 940 F. The point is that it can accommodate the the size changes that happens twice in every heating cycle as zirconia crystal structure change shape. Size change is why Zircopax (zirconium silicate) is use instead of zirconium oxide with a hard matrix like bentonite clay. Colloidal zirconia powder is a better re-radiator of energy than Zircopax, BUT zirconium silicate (Zircopax) can be made into a much thinker coating, or into tiles, which are super tough insulation; not just re-radiators, so the added work is more than worthwhile for those who want the best possible result.

However, mixing phosphoric acid into a zirconium silicate and bentonite formula would be pointless. What it would do with a zirconia/bentonite formula? Not obvious.

Link to post
Share on other sites

Kast-O-lite 30 measurement

Cast refractory mixes usually come in fifty pound bags, but there are several sellers whole sell them in one and in five pound bags for people like us. However, those bags don't have mixing instructions on them. The right amount of water in refractory mixes is critical. Frosty has provided us with this formula: 2.75 ounces of water per pound of Kast-O-lite 30. Most of us don't have small scales, but your wife's kitchen cupboard should have a measuring "cup," which has fluid ounces on its scales.

Link to post
Share on other sites

The first times we mix water into a refractory mix, the hardest thing to do is resisting the urge to use to much water to "help it mix." Patience is a much better idea, but if you want a fast mix with the minimum amount of water possible, vibration will mix the mess together like magic :)

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...