Sciencemadness Discussion Board - Hotblack

Hotblack

Ramiel - 27-3-2003 at 22:36

The pursuit of the “Ultimate Black” (a substance that can absorb all visible or non-visible light) has consumed many a scientist’s life. A recent major breakthrough in the field was documented in a recent edition of “NewScientist” magazine; it says basically that the new ultimat black has been found, and it is 1000 times more black than any previous ultimate black.

The procedure quoted for making it is surprisingly simple. Alloy 6% Phosphorus with 94% nickel, and then etch with Nitric Acid until (really, really, reeeeaaally) black. The alloy proportions are quite important, as a little over, or a little under results in a very different product.

How to alloy a reactive substance like phosphorus? One would have to do so in an inert atmosphere I guess, although suggestions are welcome.

Blind Angel - 29-3-2003 at 11:55

There is theNewScientist Article

Quote:

In the first stage, an object to be blackened is immersed for five hours in a solution of nickel sulphate and sodium hypophosphite. This produces a nickel and phosphorus coating containing between five and seven per cent phosphorus. Then the surface is etched with nitric acid to produce the super-black surface structure.

No mesure though, someone will need to try it

Quote:

But the super-black alloy is quite fragile and can easily be scratched.

I requested the document on NPL, will give you news if i receive it

Silicon.

Nick F - 29-3-2003 at 13:13

Zapping silicon crystals with the right sort of laser light also makes a very black black, although I'm not sure how it compares with this etched nickel. When viewed with an electron microscope, the zapped silicon looks like a forest of regularly arranged, thin spikes. Light gets reflected down the gaps in between the spikes many many times, and is absorbed. It was thought that if the surface could be produced cheaply and quickly that it could lead to much more efficient solar cells.

What's nice about this nickel process is that it seems very easy - I thought we might have to add ultra-pure phosphorus to molten ultra-pure nickel under argon or something...

Ramiel - 29-3-2003 at 18:56

yea, that's my bad; I had only read the article in brief in the magazine. The article does say however, that this method makes a black more than 1000 times blacker than previous blacks. (boy could that be mis-quoted!)

Organikum - 29-3-2003 at 23:56

A true challenge for the washing powder industry!

Ramiel - 1-5-2004 at 06:51

so,
"an object to be blackened is immersed for five hours in a solution of nickel sulphate and sodium hypophosphite"
"bubbling a shiny metal plate in nitric acid for a few seconds"
on furthur searching, i found that the substrate can be plastic, ceramic, metallic or glass.

what concentration and ratio of composition is the solution?
what concentration is the nitric acid?

I'll see what NaPO3 i can get a hold of and try this out.

axehandle - 1-5-2004 at 07:34

This could be a cheap way to harness the Sun's energy, with 100% absorption. Very interesting.

Tacho - 2-5-2004 at 14:55

There was some discussion about this in the “Ni from coins” thread:

http://www.sciencemadness.org/talk/viewthread.php?tid=534

From the formula given, it is pretty clear to me that they do electroless nickel plating on some surface and then etch it with nitric acid.

As I posted there, this is a description of electroless deposition of nickel:

http://www.ias.ac.in/sadhana/Pdf2003JunAug/Pe1104.pdf

I find it a most interesting reaction. I did some crude attempts to do it. I was able to get a nickel deposit on copper and, eventually, on glass. But etching with nitric acid didn’t make it any black.

If anybody is interested in doing it, I must warn that there are regulations on the sale of sodium hypophosphite that are, I believe, quite international.

...to him that linketh in prosperity, Peace be both to thee...

Ramiel - 17-5-2004 at 06:57

<html>Here is the related press release published by the UK National Physics Laboratory - <a href="http://www.npl.co.uk/press_centre/releases/2003/pr-07.pdf">link</a>

Richard J. C. Brown , Paul J. Brewer and Martin J. T. Milton, "The physical and chemical properties of electroless nickel–phosphorus alloys and low reflectance nickel–phosphorus black surfaces", Journal Materials Chemistry, 2002, Volume 12, Issue 9, Pages 2749 to 2754 - <a href="http://www.rsc.org/CFmuscat/intermediate_abstract.cfm?FURL=/ej/JM/2002/b204483h.PDF">link</a>
^^for those of you who may have access to the JMC [lucky bastards], this will answer many questions methinks.

Edit: Can someone* tell me if the concentration of NaH2PO2 is important in the disproportionation** which occurs on the substrate*** according to this reaction?

3.H2PO2- =(ads)=> 2.P(s) + H2PO3- + H2O + 2.OH

oh, and the nitric needs to be strong enough to oxidize the Ni to NiO... just a little tidbit i thought I'd share with you all.


* Smarter than me
** My spelling sucks... bite me
*** Is this the correct term? read above.


[Edited on 17-5-2004 by Ramiel]