I am working with a high school student for a science project to build a solar concentrator. The idea is to see how high a temperature can be reached on a small area. I am comfortable about the optics and solar tracking, but would like to get some ideas about what might be good experiments to do with the hot spot (other than burning paper etc.).
Keeping the thermal mass down I expect that, with a reasonable sized lens, temperatures above 600-800K should be obtainable. So my question is what kind of experiments could be done with a small hot spot with temperatures between 500 and 1000K? Are there some interesting chemical reactions that could be studied? I was thinking about using ZnO or Cerrium oxide and seeing if oxidizing and reducing reactions could be used to produce hydrogen, but I think the temperature would need to be higher. Another thought was that perhaps melting some metals or alloys might be interesting, or seeing if a phase diagram could be obtained. Obviously the spot will be small and limit the size of the experiment.
A simple thing to do would be melt aluminum. Aluminum is reactive enough that you may end up burning it in air. However, I would maybe try the coating on a welding rod- when welding, these actually produce a shielding environment. You could get welding rods cheaply, and for a high school student, perhaps free. The coating is pretty brittle and should come off nicely. This might provide a straightforward experiment that would give the student a control and treatment to compare.
Dont know if you temperatures is high enough to experiments with splitting water into hydrogen and oxygen using high temperature only. Nasa did some work in this field for space station applications:
https://www.google.com/patents/US4019868
I think with a catalyst or chemical reaction the temperature requirement can be lowered. There was some work with oxide materials where if you could cycle the temperature you could have a reversible reaction of some sort. Splitting water to get hydrogen at one temperature then restoring your material at the lower temperature. I agree splitting water by temperature alone would be very hard.
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