Anybody know how to braze diamonds to metal?

[strantor]

I've done only enough research to get an idea that brazing diamonds is something that generally happens in a vacuum, with some high dollar unobtanium flux & filler, in some high dollar microwave or furnace, in a high dollar facility, under the care of trained staff.

But that's never stopped me from trying to DIY and replicate (or approximate) the high dollar results in my garage. I'd like to take a stab at making diamond abrasive tools in the home shop.

I'll be continuing my research as this thread matures, so I may end up even answering the questions myself if someone doesn't beat me to it, But I was wondering if anybody knows a down&dirty method of brazing diamonds to steel or other metals;
what commonly available flux and filler will work?
What's the process? An oxy acetylene rosebud? Kiln? Butane torch? Electric furnace?
What temp range?
Is the vacuum absolutely necessary?

Diamond dust or granules can be found on ebay in various mesh/micron sizes.

I am mostly interested in affixing the diamond dust to wire, or to beads that will slip over the wire, which is why I'm asking about brazing and not asking about epoxy or other methods. I doubt anything but brazing would hold diamond to the wire for any length of time (except laser sintering and other unobtanium). Picture a modified vertical bandsaw with a tiny diamond-coated wire Instead of a blade. You can cut anything from balsa wood to granite to hardened tool steel with a diamond wire, and you can cut any direction you want, make complex cutouts without having to back the blade out and start from another angle. The tech is already out there, but very cost prohibitive for the hobbyist. I'd like to change all that.

Thanks.

 

[Andre]

......I doubt in a home, non scientific type shop you will have much success. Because diamonds are mostly cabron, it will be hard to braze it. The carbon will be basically too slippery to stick.
When brazing in sensitive areas (say filling in a counterbore or chip around a hole) you'd use a carbon plug that fits snugly inside the hole. You can braze against the carbon, then pull it out later leaving a clean edge remaining. You can see this process in full in a video series by Keith Fenner (on youtube) called "Dam Brazing" and as the name suggests, he used a piece of carbon rod to create a dam.

I think you should leave this to professionals, but I am in no way suggesting you not do it. If you do it I think you will learn a lot, and might just happen to make a useful product.
I'm interested in what others have to say, I'll subscribe to this thread.

Good luck!!

On second thought, is there a way you could grow crystals on the surface that is desired to be coated? They won't be diamond, but they would still be abrasive. Like those grow your own crystal kits, but with a harder material.

 

[Ebel440]

I think it may be possible to buy a wire coated with diamond as a blade for cutting stained glass I know they had wire rings but it was heavier wire which would not bend.

 

[churchjw]

Not sure it is helpful but I have cast diamonds in place in silver and gold. Using lost wax casting you put the diamond in the wax just like it would be in the metal. Then melt the wax out and poor in the metal. As long as you don't quench the casting the diamond does just find. I am not sure diamonds are brazed in place as much as they are just trapped in brass. I know I broke a single diamond dressing point once and it just looked like the brass ripped and it popped out. The brass wasn't stuck to the diamond it was just around it holding it in.

Jeff

 

[John Hasler]

You can't braze to graphite because the surface layers of the two-dimensional crystals just slide off. That won't happen with diamond. It is pretty slippery, though.

My first thought is to make a suspension of diamond powder in a soft nonferrous metal and then dip (properly fluxed) steel wire in it. You probably need to do everything under argon to keep the diamond from oxidizing. The soft metal will quickly wear away when you start cutting exposing the sharp points of the diamond.

Lots of fiddling getting the diamond powder to stay suspended, getting the concentration of diamond just right, choosing the right carrier alloy, getting the temperature correct, getting the viscosity correct...

 

[Ebel440]

I think its cobalt that holds the diamonds to the base metal I don't know why or where I read it so it may be incorrect. I know carbide tools are also cobalt so maybe it has an affinity for carbon?

 

[Ripthorn]

A lot of diamond coatings are done with a nickel bonding process with which I am not totally familiar.

As for your question regarding the vacuum, it is probably necessary, as with a good vacuum, you can evaporate metal at low temperatures and perform a process called "vacuum deposition". It is a lot of fun to watch a solid block of metal turn to gas at roughly room temperature. We did this back in school with aluminum in my senior experimental physics class. And the vacuum systems they use are much more than anything you will find in a typical shop.

 

[Ebel440]

I was wrong it was nickel For diamond as he said above. I believe vacuum deposition requires an electric current as well as a vacuum

 

[strantor]

Yeah what you gents are saying is in line with what I'm finding - which is to say, not much hope with not much money and brains. So I'll settle for replicating the results, or trying to anyway. So does anybody have an epoxy in mind that they think might cut the mustard? If I'm going with epoxy then I might as well go with a carbon fiber core instead of steel wire; it would be much easier and stronger to create a seamless loop of carbon fiber tow, by wrapping it around a few hundred times, than trying to weld steel wire end-to-end with no bulge and no weak spot. Plus I hazard a guess that I could have much many more options on the epoxy I use - not as many things adhere well to smooth/plated/galvanized metal. Whatever epoxy would need to be flexible, tough, and have decent heat resistance. And of course form an extremely good bond with diamonds as well as carbon fiber (although more importantly the diamonds).

Also it would be handy if it were UV curing; that way I could drag the wire/fiber loop through the coating process, through a UV cure box, and have it emerge as an already-set-up deal. That way I won't have to handle the wire/fiber loop with virgin epoxy all over it and risk screwing up my work.

 

[Ebel440]

I've made some stuff from carbon fiber and think you would be better with steel wire. I was able to sand carbon fiber to shape I don't think it would resist the abrasion well at all. While the diamond would help there will be areas uncovered and would wear quickly I think