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Author Topic: Are there materials that change colour at high temperature?  (Read 1538 times)

Offline thedoc

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afsane ghorbanzade  asked the Naked Scientists:
   Is it possible to guide me? I need a series of materials that change their colour by high temperature steam (I mean they respond to specific conditions of time, temperature, humidity, pressure and the presence or absence of certain chemicals by changing colour) I need a list of material sensitive to steam in high temperature (over 1210c) It is much better that it is not toxic. The degree of toxicity is low. Now can you help me to find of list of these material?
 
What do you think?
« Last Edit: 05/02/2016 19:50:01 by _system »


 

Online chiralSPO

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hmmm...

High temperature steam is pretty corrosive stuff, and 1200C is really hot! So if you want to pass the steam directly over a material, you have to consider the color changing aspect as well as stability under those conditions.

There are plenty of substances that change color depending on the presence or absence of chemicals, but I have to know what you're looking for to know what types of compounds to recommend.

There are also compounds that change color depending on what temperature they are. The first one that comes to mind is sulfur, but that would definitely not survive those conditions, if it is in direct contact with the steam. Even if it is separated, sulfur boils at about 450C, so it would need to be pressurized, and I don't know what the useful temperature range is, I've only looked at sulfur as a temp indicator between -30C and 250C...
 

Offline evan_au

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A change of color is a useful indicator to human vision, especially if it is a reversible reaction which can be mass-manufactured with no moving parts and no electronics (think pH indicator solution in chemistry class, or LCD temperature strips).

However, no human can survive temperatures over 1000C, so the stipulation of a color change as the indicator seems somewhat superfluous.

There are plenty of sensors for:
  • temperature: including resistance and infra-red sensors.
  • pressure: Mostly mechanical.
  • gas composition: including infra red spectroscopy and chromatography.
  • unfortunately, these sensors mostly use electronics and computers for real-time measurement, logging and control

In addition, materials over 500C start to glow with visible light, with colors including "cherry red", yellow and orange. So color change is really only useful as an indication of temperature, not any of the other factors that you wish to measure.

See: http://en.wikipedia.org/wiki/Red_heat
 

Offline Bored chemist

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I'm willing to bet the OP meant 121oC which is the "usual" temperature for an autoclave.
Something like this would be worth looking at, but I haven't seen one which works at that high a temperature/
https://en.wikipedia.org/wiki/Liquid_crystal_thermometer
 

Online chiralSPO

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ahhh 121C would make MUCH more sense!
 

Offline Ernie Paulson

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Is this an irreversible color change?
 

Offline Bored chemist

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