The authoritative public forum
  for Metal Finishing since 1989
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Black chrome

Can Black chrome be used on the outside fins of engine cylinders? Would that have the same heat radiation transmittance qualities solar collectors have? Will it have the ability to radiate heat away, like solar collectors receive?

Joseph D DiTommaso
- Denver, CO, United States
2005

A "black body" is a theoretical concept in modern physics for an object that is a perfect emitter and perfect absorber of radiant energy. In the real world, the more black is an object (charcoal or graphite seem to be very close), the more it gets close to the concept. So, I guess the answer to your question is yes.

Guillermo Marrufo
Monterrey, NL, Mexico
2005

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Black chrome is mainly used for solar collectors.

Sara Michaeli
Tel-Aviv-Yafo, Israel
2005

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2005

Joseph

If you want to remove heat, black is not a good idea.
Check bike fins. How many makers use black fins and how many don"t ?

Keeping an engine cool by radiation and airflow may need a second look at the Black chrome approach.

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016

In my previous answer I was talking about a theoretical concept. Now, a black "real" object indeed absorbs heat more easily than, for instance, a white one when it is colder than the surrounding. We all have felt the sensation or wearing black clothes under direct sun light instead of wearing clear ones but our body is obviously colder that the sunlight. The situation described is the opposite. The surface of a running motor is far hotter than the surroundings, which turns it to an emitter instead of an absorber. In this case, strange as it may seem, the physicists tell us that a white object looses the race against a black one because it may radiate in a definite wavelength span whereas a black one does it in all wavelengths, including infrared. Pure theory. Do we believe it?

Guillermo Marrufo
Monterrey, NL, Mexico
2005

Just to give some numerical relevence, black chrome has been recorded to have absorbtivity of 0.98, but unlike an ideal black body, it has an emissivity of 0.05. So although in theory a black body would be ideal for this situation, black chrome is not the black body you want in this situation.

Attila Ferenczi
Engineering - Kelowna, BC, Canada
2005