dust free refractory materials 3

[HDS]

I am looking for a refractory material that is not dusty to the touch. Something like a piece of ceramic cookware would be perfect. I have scoured the web and talked to suppliers but have not found anything. The part is a disc 4" diameter x 1" thick with a hole in the center. I would like a thermal conductivity below 1 W/m·°K. The max service temperature is 700 C. Does anyone have a suggestion for a material or a supplier in the US?

 

[moltenmetal]

1W/m K is going to limit your choices severely.

Perhaps a piece of ceramic fibre millboard with a coat of rigidizer?

 

[HDS]

The millboard is what I am starting with and where I got the thermal conductivity goal from. The rigidizer helps but it is still dusty. Is there a glaze that can be applied on top of the rigidizer?

 

[boilerone]

Not sure if it is because you have erosion concern but you can consider the type of refractory bricks used for internal linings of the stacks in power plants which have wet and corrosive flue gas after flue gas desulphurization or the ones used for industrial kilns of wear and corrosion issues. These bricks have ceramic-glazed faces. You can search this kind of vendors online and get their data. This one should have what you are looking for:

http://www.hwr.com/

By reading their product data sheets if the thermal conductivities are too high you can use a multi-layer structure with insulating (dusty) refractory on the cold side and ceramic-glazed brick or just thin tile on the hot side.

Boilerone

 

[HDS]

The furnace I am using it with needs to be clean and free of dust. So I need something that is not constantly shedding.

I couldn't find anything on the HWR webpage and haven't gotten the right person on the phone yet. Do you have a link to specific product I could look at? What are these glazed bricks usually called by the manufacturer?

 

[moltenmetal]

A vitreous glaze might work, but might also crack. You'll need to talk to somebody like Thermal Ceramics to figure this one out.

 

[boilerone]

They used to have downloadable pdf files online. They might have changed since then. You probably need to request a CD which has all product information including data sheets plus a selection and thermal conductivity calculation software. We got the CD when they visited our office. It even requires a code to activate.

It's best to talk directly to their sales or technical person since you have a quite special application and dimensions.

 

[unclesyd]

There are several ways to go depending on the requirements on the insulation besides the TC. Low at the products from the following companies for "low shot" and abrasion resistance and what compressibility factor you need.
f the insulation is going to be a working floor it will require special attention and probably require a composite structure.

With the information given a Mica based material would be ideal but your temperature is a little high.

I would give any of the manufacturers a call if something looks close to your requirements.

http://www.thermalceramics.com/site.asp?siteid=4&pageid=63

http://www.zircoa.com/product.coarse.grain/kiln.furniture.std.sizes.plates.discs.html

http://www.zypcoatings.com/ProductPages/Products.htm

http://www.foundryservice.com/ceramic_fiber_products.html

 

[HDS]

After contacting everyone in these posts and the guys they sent me too I ended up with a refractory with a coating. The recommendations were all very good.

It has a small amount of dust but it works. The materials that were dust free on their own were too dense and thus too high in thermal conductivity. So a less dense material with a coating was the compromised solution.

 

[diskullman]

Vermiculite board?


Russell Giuliano

 

[HDS]

I looked at that and it wouldn't work. I think it required a sealant to prevent damage from moisture in the air but there could have been some other problem.

 

[boilerone]

HDS,

Typical method to deal with your problem (thermal conductivity too high) is to use a two-layer design which has an 'insulating refractory' layer between the hot layer and the part that you want to protect.

It is a very common design practice.

Boilerone