wear resistant

IF use sheet of microporous alumina will not have this problem. The life will improve

THANK YOU FOR SUGGESTION.CAN YOU GUIDE THE SUPPLIERS AND THICKNESS,PL.

at 1300 C, Alumina has issues with thermal shock.

You are too hot for Quartz/Silica, so you may want to try SiC for the surface. Contact

Saint-Gobain Ceramics / Crystar. They are is Worcester MA.

Dense alumina has issue not porous alumoina. Porous alumina is developed to take thermal shock and because of porosity does not allow crack propagation and failure.

If mullite would have worked then it was best solution. I have used mullite form glass melting when the glass was not reactive and reactive glass I used miroporous alumina and used for multiple times and does not see failure.

Other alternate is zero expsansion glass ceramic materials. Based on material you may think about Corning cookware which is from freezer to hot plate but is good only up to 800C and is reason I have not mentioned in earlier suggestion.

For my application I make myself but I am sure you can find manufacturer who will do this. There was guy having company in San Diego making porous ceramic plates (I think it was RTI corporation (I may may be wrong Owners first name is Randy.

I will be more than happy to share the way I make it of that will help you

Dear sir,mullite was good refrctory,but erosion was very fast.sandwitched sic and mullite-sic-erosion was fast and thermal cracking by mullite. could you plese explain how to make microporous alumina.if it can withstand themal shocks -refractory wise its best.pl.explain or mail the process- venuitausa@yahoo.com thank you.

thank you sir, we have started with black sic-erosion was v.fast and heat conduction was also high.sandwitched sic and mullite-with sic as face-erosion is v.fast.

There are higher purity SiC that may offer better wear resistance if the Alumina as mentioned above do not work due to thermal cycling.

To help with the thermal conductivity, what will the cold face temperature reach on this plate? If you are <1200 you may have luck with opaue quartz material as an insulation layer. Depending on the load, there are opaque quartz glass materials or for light loads there are low density rigid products that have great thermal conductivity properties.

We use it at 1550C and have no problem with cracking of reliability

Masyood

I am not as familiar with the grades of Alumina. I am very surprised with the temperature limits and thermal shock resistance.

I am sure that the thermal conductivity will be sufficient for this use as well. It is certainly less complicated than multiple layers of material.

Alumina comes in different grades ranging from 84% to 99.9%. Higher the purity cleaner the alumina is and costly.

Most of alumina will be very susceptable to thermal shock if it is dense. As density comes down so does improvement in thermal shock resitance and is very normal materials phenomena.

If one makes alumina with micropores its thermal shock reistance improves.

This is the technology I have used good number of time. Currently if you have car with catalyst converted it has platinum on porous alumina which takes thermal and vibrational shock and the porosity is less control since we needed to move gas out through converter and same time convert CO to CO2 so do not poison air. Technology is not new. New is only created miroporous plate of alumina bu controlling pore and pore size distribution so that capplilary action does not pull water through

Masyood

The micro-porous condition is most likely why I am not as familiar with the material. I typically work in environments where we need to limit porosity and need very high purity. 99.9% minimum usually greater.

I work with fused quartz and synthetic fused silica exclusively. I also work with sintered silica mateirals (slipcast). Typically my materials although sintered will still be a consolidated glassy material through the wall section. The density of my fused glass is about 2.2, the slipcasts are very close to this density as well, approximately 2.1

I appreciate your explaination of porosity and thermal shock resistance.

Silica has density of 2.2 true. and has used up to 800C but one can also make silica with density less than 0.5 gram /cc density instead of 2.2 using process Sol-gel merged with hypercritical drying .

This technology have only 10% solid and is very good material to replace boron rod to control temperature and adsorb hot neutron in atomic power plant .

This porous silica eventually is a commercial product as replacement of boron rod to run atomic power plant.

Porosity has amazing advantage and if controlled properly brings lot of good things together to meet new challenges we face.

Masyood

Dear Masyood and SGQ, THANK YOU VERY MUCH FOR SHARING THE VIEWS AND EXPERIENCE,EXPERTNESS. WITH BOTH OF YOU, HAVING SUCH GREAT EXPOSURES -WHICH SHALL BE THE BEST FOR OUR PROJECT. MR MASYOOD,AS I REQUESTED EARLER TOO,PL.TELL ME HOW TO MAKE POROUS ALUMINA SHEET.PL.HELP ME.

Porous alumina is properitory of business and is not a hard to do. As a consultant I have developed for one of the customer.

Making control pore size and distribution for specific end use is unquie and is end need depended. I have to learn more more you need then I can say how to do it. Like when Johnson Matthey wanted to develop carrier for platinum on alumina I developed that by dipping spung in alumina casting slurry and then using spung as fugitive component to remove during firing which end up giving structure same as spung. Then they deposited platinum and to-day the product goes in automobile exhaust system to convert CO to CO2 and minimize damage to envirnoment.

You need my guess is finner and more defined porosity in alumina sheet which thickness I am not sure. This for filter development needed organogetallic and char type organic which chars and does not burn out cleaning at low temperature but provide enough gas evolution to have porous alumina.

Masyood