You can totally make a mixed-matrix metal oxide aerogel using the epoxide-assisted gelation method. Why are you choosing to use TiCl3? You can use TiCl4 also, which might be easier. You do not need to use the nitrate for the iron salt–you can also use FeCl3. The technique is sensitive to the amount of water more than the pH, but as the reaction proceeds there is a slow, constant rise in the pH as the epoxide scavenges protons from the aquo complexes formed in solution. You’ll want to play around with solvents since TiCl3 and TiCl4 are both easily hydrolyzed and react with many protic polar organics such as ethanol and methanol and you will need to include water in the system from somewhere, for example, as water from a hydrated iron salt. Consult the papers of Gash et al. to see examples of what solvents might be best. You could try acetonitrile as a start.
What you would most likely end up with is carbonized powder with micron-diameter aluminum nanoparticles embedded throughout. I don’t think you would etch the nanoparitcles because, as you correctly pointed out, aluminum reacts readily with oxygen or water to form a protective oxide barrier that inhibits further oxidation making the particles very stable. Additionally, aluminum oxide is hard to reduce to aluminum metal carbothermically, and so even under these conditions I’m confident the aluminum would not etch substantially.
Question for an expert wanting to assist in designing a more effective fire protection gel. I work in the major motion picture industry as a stunt coordinator and performer. Currently I use a protective gel to coat the skin of a performer when working with fire stunts. I’m interested to learn if there’s a way to create a jelly like substance out of aerogel that can be used instead of the current formula. Please reply if you’re interested. I’ve attached a photo of what my current gels are capable of. Though they’re limited in protection time. Right now I can burn for 15-30 seconds depending on the type of fuel used. Actor in the background, my hand in the foreground.
I am drying isopropanol (IPA) alcogels (rinsed 4 times after synthesis with reagent grade isopropanol – but not necessarily dry because the bottle is open to humid air when pouring, etc.). I am pressurizing to roughly 1500 psi and heating to roughly 300 deg C (beyond the critical point of IPA). However, I am getting cracked, somewhat-shriveled pieces, and not un-shrunkened monoliths after sc-drying. I heat the sample in about 1 hour, hold beyond the critical point with periodic venting to prevent excess pressure for about 1 hour, hold isobarically and isothermally at about 300 deg C and 1500 psi for about 1 hour, and finally depressurize over 1 hour. I also pull a vacuum on the autoclave once it is fully depressurized until it cools to below the normal boiling point of IPA. Could the problem be residual water in the IPA (up to 12% by mass, unlike EtOH which picks up only ~5% water)? Is water soluble in scIPA? Am I depressurizing too fast? Any suggestions? Should I just do scCO2? If so, do I have to re-exchange the IPA away with acetone?
I am a graduate student in the department of Mechanical Engineering at Georgia Institute of Technology. We are trying to synthesize transparent silica by supercritical drying. We followed the gel synthesis protocol described in this website. The gel looks good as expected. then we did the ethanol exchange 4-6 times and put it in the Tousimis supercritical dryer. we purged it for 10 minutes with CO2 and with 24 hours of 3 stasis cycles. It is transperant aerogel at the surface but opaque white inside. the samples are cracked as well. Could you please suggest what could be the reason and what parameter should we play with to improve our samples?
I am a graduate student in the department of Mechanical Engineering at Georgia institute of Technology. We are trying to synthesize transparent silica aerogels for the application of radiation detection. We followed the protocol described here for making gel. the gel looks good as expected. We did the ethanol exchange for 4-6 times. Then we did the drying in Tousimis dryer under supercritical conditions. We purged it with CO2 for 10 minutes and used 3 stasis cycles with 24 hrs interval. We got the transperant aerogel at the surface but it is opaque white inside. The samples are cracked as well. Could you please suggest what could be the reason and what are the parameters we can play with to fix it.