Diamond Replacement Squeezed Out in Ukraine

rw2 writes: "It's not going to replace the rock that your girl demands for her finger anytime soon, but a new material - cubic boron nitride (cBN) - is being compressed into a cubic structure with properties similar too, but in some ways better than, those of a girls best friend. Read about it in The Cern Courier"

Re:This is new?

[stevelinton]

I think you did miss something, although the article almost misses it too. This is not, actually cBN, but cBC2N and cBC4N. That is, the compound is a mixture of carbon, boron and nitrogen, in the cubic lattice, not just BN (cBN) or just C (diamond).

Diamonds are

[BlackHat]

trolls best friend.

But how is this thing’s cleavage?

[heliocentric]

I've always enjoyed talking about the cleavage of rocks since so many people think I'm insulting them, "Hey, I saw you two got engaged, looks like you got some nice cleavage..." If this thing ruins that gag I might just have to stoop to asking: "What does Moh [24carat.co.uk] think of your hardness?"

why?

[nomadic]

If Zork has taught us anything, it's that you can manufacture diamonds by getting a piece of coal, a screwdriver, a sprig of garlic, a lamp, an ivory torch, then going past the vampire bat into the mines, putting the torch and screwdriver in the basket, then lowering the basket, going through the mines using the lamp to light your way, drop the lamp so you can squeeze through the narrow opening, retrieving everything from the basket, then putting the coal in the machine and using the screwdriver to activate it. Beautiful diamond, easy as can be.
--

This is new?

[SlashGeek]

Unless I missed something in the article, this doesn't seem all that new. CBN has been used in the machining field for a number of years in various forms. It has been plated onto conventional cutting tools such as drills, milling cutters, and lathe tools to increase wear resistance, likewise with diamond coatings. It also finds widespread use in precision grinding. In fact, in some applications CBN outperforms diamond grinding wheels. Not so much that it is better than diamond, only it is less expensive to produce in larger grain sizes required for cutting softer materials to resist clogging. By the nature of industrial diamond manufacture, it is difficult to make diamond "dust" in larger grains. In an ordinary application, you would cut a material with a harder material; either a harder steel or carbide or an abrasive. Cutting the hardest material known to man obviously presents challenges. Imagine cutting down a tree with a wooden saw and, well, you get the picture.

In grinding applications, CBN and diamond wheels are produced basicly the same way. Either a metallic or plastic wheel is coated with a layer of CBN or diamond at it's working surface, and usually bonded with a rubber, plastic, or epoxy material giving a usable life in most applications of 1/8 to 1/2 inch of wheel wear before the abrasive material is exhausted and the wheel is bare. There are, of course, exceptions to all of these guidelines for special applications etc. Wheels are usually dressed (flattened or shaped) with a special stone or Norbide (tm) stick, basicly an extremely hard, brittle peice of carbide that quickly accelerates the wear of the bonding agent. Other coating methods are used on HSS and carbide cutting tools, such as electoplating and vapor deposition. The coatings work in several ways to protect the cutter, direcly and indirectly. The high thermal conductivity of both materials quickly dissipate heat from the tooth, as well as providing sort of a lubricant that also has the effect of creating less heat. They also decrease physical wear on the tool, allowing it to run for longer periods without loosing accuracy, cut more aggressively, or cut tougher materials.

There are many other advantages (and some disadvantages) of CBN, but overall it has found a rather large niche in metalcutting. MSC Industrial Supply [mscdirect.com] has a large selection of CBN and diamond products, just type "CBN" in the quick search field and check out some of the tools that CBN has been used on for years.

Her ring.....

[SouperMike]

Yeah, she still wants a huge, boring diamond. But we're getting matching rings... She gets the diamond and I get the cBN ring.

Just so she remembers who's in charge.

Re:This is new?

[cpl almost]

You may or may not be correct here, its very hard to tell. What you have discovered is, IMHO, one of chemistries dirty little secrets.

The article talks about BC2N and BC4N, boron carbonitride. You refer to the apparently common CBN, carbon boronitride. The trick is they may be the same thing! As far as I know there is no strong convention for naming covalent complexes like this. Generally one tries to alphabetize (e.g the researchers use of this convention), however, engineers have this nasty habit of ignoring international convention in the "pure" scientific disciplins (metric?) and so somebody probably named the cutting material you describe CBN and it stuck. In short, CBN == BC2N

As support I suggest that the lowercase c, (cBN) is very important. In chemistry, (I don't know about materials) lowercase prefixes often denote geometric/ spatial/ optical isomers, in this case cubic. Also, the fact that it is harder-than-diamond is key, this is unique as far as I know. Finally I would mention that the intial description of cBN (cubis boronitride?) makes no mention of carbon whatsoever, yet at the close of the article it is described as cBC2N. I believe this is a case of a journalist who does not understand the material s/he is covering.