I am working on a project looking at sourcing a sealer for a ceramic composite material.

We are making high temperature internally-heated composite molds for the aerospace industry based on embedding electrical resistance wires within a ceramic-like material reinforced with glass fibers. Temperatures may reach up to 250C.

The problem is that when cured, the ceramic material has an inherent porosity ? this means that is very difficult to achieve full vacuum on the A-side when materials are processed in production (pre-preg vacuum bagging). We need to find a suitable sealer that can be sprayed on and cured after the mold is made. The sealer must be temperature-resistant, tough, damage/scratch resistant and provide full vacuum integrity. We also need to be able to apply a mould release periodically to assist in part removal.

Ideally, we need a sealer that can be applied in-house, as the moulds would in some cases be too large to send away for treatment.

Any advice would be much appreciated.

Hi murt100

to the Surface Engineering Forum.

Most organic type sealers (epoxy, polyurethane, acrylics etc.) will not be suitable at 250 C.
Silicone resins may stand a chance. Really, inorganic sealers usually based on silicates are probably the best bet. Ideally, sealing should be done with the aid of vacuum or high pressure impregnation.

Hope that is of some help.

Hi murt100

Quote: to the Surface Engineering Forum.

Most organic type sealers (epoxy, polyurethane, acrylics etc.) will not be suitable at 250 C.
Silicone resins may stand a chance. Really, inorganic sealers usually based on silicates are probably the best bet. Ideally, sealing should be done with the aid of vacuum or high pressure impregnation.

Hope that is of some help.

Further, you may also have to consider the porosity size vs. sealer material molecular size to be sure that penetration is possible.
bhe

bhellman Wrote:Hi murt100

Quote: to the Surface Engineering Forum.

Most organic type sealers (epoxy, polyurethane, acrylics etc.) will not be suitable at 250 C.
Silicone resins may stand a chance. Really, inorganic sealers usually based on silicates are probably the best bet. Ideally, sealing should be done with the aid of vacuum or high pressure impregnation.

Hope that is of some help.

Further, you may also have to consider the porosity size vs. sealer material molecular size to be sure that penetration is possible.
bhe

Hi,
For sealing ceramic surfaces, please check in the chapter containing cermaic sutface modification (p279-) and also on chapter on microwave(p149--), in my following book,
Advanced Thermally Assisted Surface Engineering Processes, Kluwer Academic Publishers, MA,USA,2004,ISBN 1 4020 7696 7.
You can contact me for any further assistance if you need.
Also visit my website:www.wearprognosis.com
ram chattopadhyay