Midterm Project (Exploring the Vacuum)
a joint project with Johnny Lu
Our project focused on a less structured approach to materials exploration. We set out with a very general thesis… build a specialized environment, a vacuum chamber, and see what kind of interesting results could be achieved with unique materials and material states within it.
We fabricated our chamber using a 9 inch stainless steel vessel obtained from a restaurant supply, an air-driven vacuum pump, high-pressure ball valves, negative pressure gauge, silicone gasket, .7 inch acrylic, and plywood. The air-driven pump was rated at -28.3″ Hg (95 kPa).
Our initial tests achieved about -15″ Hg (50 kPa), later we were able to bring the reading down to nearly -28″ Hg (93 kPa) after we increased the drive compressor from 90 psi to around 120 psi. The chamber was able to hold a vacuum for an extended period without and signs of leaking, -a lucky first success!
A short video of initial testing:
We decided that our first experiments would focus on the effects of a vacuum on super-saturated solutions, namely: sugar in water and plaster of paris mixed with CO2 saturated water. The idea was that super-saturated solutions are stabilized by specific atmospheric and thermal conditions and that we could potentially alter those conditions within a vacuum -particularly while the solutions were undergoing transitional phases such as the cooling of a sugar solution or the exothermic reaction of plaster into a solid.
We transferred the mixture to the vacuum chamber and began decompressing the chamber to 90 kPa. The reaction was nearly instantaneous… the solution bubbled over releasing a large amount of the water as vapor after which the remaining sugar seemed to instantly crystalize and harden. The water vapor released so quickly that it obscured our viewing window:
After reaching maximum vacuum we let the mixture cool for 15 minutes in the vacuum then opening the chamber to reveal a super hardened cavitied mass of solid sugar:
We partially disolved the hardened sugar with hot water to see it more clearly, the structure was very hard and resembled coral or lava rock:
We expected little to happen with the distilled water mixture, but were not entirely sure what to expect from the super-saturated water.
As we evacuate the chamber both solutions began to bubble but as the vacuum increased the CO2 saturated mixture began to expand rapidly:
While it is often standard to de-gas casting materials prior to casting in a vacuum chamber we thought the resulting in-vacuum cast to be very interesting -essentially creating a lighter weight equivalent volume of cast material.
Ulterior Motives (X-rays)
The fabrication of the vacuum chamber was motivated in part by the possibility that it might facilitate an inexpensive X-ray source using scotch tape a phenomenon researched at the University of California, Los Angeles in 2008.
If we are able to produce X-rays with the chamber we hope to use it too effect mutation rates in different plant seeds.
Another possibility would be to make a cloud chamber.