Looking for Hard Material that is Black

I looking for a material that is black naturally(pre-mixed). You want a liquid material you can cast? What difference does color make?

This material hopefully can be as hard as steel but still machinable. Then, just use steel.

Going to make a calibration jig using this material with some inserts onto the surface. What tolerances do you need to hold? What material are the inserts?

You need to tell us what you are doing.

Some kind of black rock, maybe? Does it need to be black all the way through, or could it be plated/anodized after machining? How soft is allowable?

I'm just casting in the dark here; a materials expert can surely do better.

Hi Tornado and Lyn,

We are currently anaodizing it black but the problem is the anodizing is not consistent from batch to batch.

It is used as calibration jig for my vision camera so the finish and consistecy has to be there.

The inserts are steel pins. So the machine has to be able to hold the pins in place and not deform over time. I am measuring the height, position of the steel pins.
Blackening helps to provide a constrast between the pins and jig.

My measurements accruacy are in 5-10 microns.

I'm not a material expert and hope someone who is in that field can give me some advise.

Thanks.

It comes down to what's more important. Color or thermal stability of the jig. If you can control the temperature of the jig and test piece, then you may be able to get to 5-10 microns of resolution.

I'd look at ceramic materials, they are thermally stable. I don't know about black, but coloring ceramic shouldn't be too difficult.

Tell us more.

My measurements accruacy are in 5-10 microns.

Well painting or surface coating are out of the question if this level of accuracy is required across the surface.

Anodizing is probably your best bet, you may just need to deal with a different company that can offer a more consistant finish.

If you need a material which is very thermally stable, you can't do much better than Invar, a iron/nickel alloy which has very nearly zero thermal coefficient of expansion over a wide temperature range. If your jig has got to be thermally stable, you can't go wrong with Invar.

To get the black finish, apply it separately. Special black coatings are available which reflect at most 2% of incident light, on average, and considerably less at some wavelengths. Certain nanomaterials do even better at absorbing incident light, but the coatings are fragile and difficult to apply.

I would avoid anodizing if stray light is your concern. If the surface is smooth, anodising the surface will reduce stray light only so much regardless of what colour anodisation you use. If you look at a black-anodised surface nearly edge-on, you'll see that it reflects light rather well. Better to use a 'flat' treatment if possible.

Consistent anodizing may require close temperature control of the anodizing tank; i.e., refrigeration. Does the present metals finisher have that capability?

Carbon fiber?

It's become pretty popular...............strong and black too. Here's one example:

http://www.swissinstruments.com/starrett_carbon_fiber_snap_gauge.html

https://www.bing.com/aclk?ld=e8dhNHOioRh42hFEBs_wMHGjVUCUzx5lh6-homIkznVqT2ENDKJP07xwrBw_189CT4sHacqXBdldZ6IMpquxtJJugASMHTmderJlWmAT4KDIHXx4DiHQHsYMyBfj_oDcVmpC-hIWobn3BIsW-0TkjeQVAqM3S-m_D7fC70QMBNgCR4Yy969MMOFUfERhW8uqfm7LRPDQ&u=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&rlid=610a02ad2f731993df5d647c8bcd8e3e&ntb=1