Easy-to-Make Material Scratches Diamond

holy_calamity writes "A material tough enough to scratch diamond that can be made without resorting to massive pressure has been developed at UCLA. A regular furnace and a zap of current is enough to meld boron with the metal rhenium." Sound familiar? This is the other new material tougher than diamond, but no word yet on how they rate against each other.

Comments

Stiffer, not harder

[caramelcarrot]

The old material was stiffer, not harder, than diamond. It could still be scratched by diamond.

This costs about 5x abrasive-grade diamond

[Tom Womack]

Rhenium costs £6.50 per gram if you want to buy it on ebay; boron is £13.50 a gram on ebay because the one seller there is selling an exotic crystalline form. [ebay search for 'rhenium metal' or 'boron element']

So making ReB2 using source materials bought in small quantities on ebay would be about ten pounds (about twenty dollars) a gram; probably the cost of the electricity to run the furnace would be more than that, and the depreciation on the furnace more still.

I paid ten Euros (about fifteen dollars) for the diamond sample I have, which is two milligrams, and various diamond-industry sites give prices on the order of a hundred thousand dollars per gram; of course, rather like microchips, diamond pricing is exponential in the size because you have to find one big diamond rather than gluing two small ones together.

But ReB2 will be competing with diamond abrasive, and http://www.diamondtech.com/products/categories/dia mond_powder_price_list.html will sell you twenty grams (a hundred carats) of half-micron diamond dust for fifty dollars which is a lot cheaper than either the rhenium or the boron.

http://www.metalprices.com/FreeSite/metals/re/re.a sp suggests that bulk rhenium is $3000 per pound, which is a bit over half the ebay price above; some sites, I think mostly run by gold bugs, suggest $6000 per troy ounce, so either there's an opportunity for arbitrage, or they've confused rhenium and rhodium.

The not-so-trustworthy-looking http://biotsavart.tripod.com/bmt.htm has boron at about $5000 per kilogram, so $2200 per pound; still these are orders of magnitude cheaper than diamond.