Rhenium diboride

"A super-hard material that is tough enough to scratch diamond could be made cheaply and easily, a new study suggests. The material is made from
the metal rhenium and the element boron and resembles both a metal and a crystal in structure."
http://www.newscientisttech.com/article/dn11670-supertough-material-mimics-metal-and-crystal.html
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Richard J Kinch wrote:

http://www.newscientisttech.com/article/dn11670-supertough-material-mimics-metal-and-crystal.html
Sounds OK, but what of toxicity? Can't find much on that.
--
Dirk

http://www.onetribe.me.uk - The UK's only occult talk show
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wrote:

Are there any gem-hard txic materials? And how are those rings and rods a'coming?
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And Rhenium is only $5000 per pound, great idea!
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snipped-for-privacy@sbcglobal.net wrote:

What does a pound of diamond cost? Natural diamond dust is about $(US)1/carat or $2300/lb (depends on particle size and shipping unit) - and it cannot be used to process ferrous alloys because of catalyzed graphitization.
The real concern is hardness vs. orientation. Diamond cutting is a bitch if you stupidly choose a hard direction to facet. Rhenium diboride is only as hard as c-BN overall, except in its hard direction. Oriented embedment will be necessary to expedite diamond facetting - and that is not the way the industry currently works.
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Uncle Al
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Uncle Al wrote:

I imagine that density would be a large factor in determining cost of use. Every price was given in $/LB, but coating a surface or tool wear is volumetric in nature. 21 g/cc for rhenium diboride vs. 3.5 g/cc for diamond. Perhaps the price should be listed as $USD/cc I got really confused by the "could be made cheaply" statement in the first sentence of the article.
I guess I'll just keep rereading the article until I understand what cheap means ;-)
Gregg
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: snipped-for-privacy@sbcglobal.net wrote: :> :> And Rhenium is only $5000 per pound, great idea! : : What does a pound of diamond cost? Natural diamond dust is about : $(US)1/carat or $2300/lb (depends on particle size and shipping unit) : - and it cannot be used to process ferrous alloys because of catalyzed : graphitization.
Too bad that Uncle Al is keeping his process for making kg-sized, gem quality diamonds such a highly-guarded secret. -- highly guarded to the extent that he's been promising us the diamonds for over a decade and has yet to produce any.
----- Richard Schultz snipped-for-privacy@mail.biu.ac.il Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel Opinions expressed are mine alone, and not those of Bar-Ilan University ----- "It is terrible to die of thirst in the ocean. Do you have to salt your truth so heavily that it does not even quench thirst any more?"
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Is ReB2 actually harder than diamond in that preferred direction?
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Apples and oranges. The diamond price is delivered product after processing. The Rhenium price is for raw powder only usefull for processing into alloy. As yet there is no process for casting any significant amount of ReB2. What the researchers have is a process that consumes a quantity of very expensive powder along with great quantities of electricity and produces an unmachineable lump. Real usefull!
starbolin
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snipped-for-privacy@sbcglobal.net wrote:

You don't know crap about research, development, process engineering, and product placement. Rap music flies off the shelves on Monday and into garbage cans on Friday at $19 the dose. Something uniquely useful will also find a market.
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Uncle Al
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Uncle Al wrote:

I was thinking jewellery, specifically, rings.
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Dirk

http://www.onetribe.me.uk - The UK's only occult talk show
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Simmer down Al. I don't recall attacking you personally. Lets keep it civiI. I was attempting to provide a counterpoint to the article's glowing optimisim.
ReB2 seams to be a very interesting material and it seems there would be a market for it somewhere between CBN and diamond but here would need to be a process to manufacture it and, as yet, the only proven process is CVD.
Let us do indeed run some "development" numbers. The world industrial diamond market is something like 200 tons a year. So a company wanting four percent of that market would need to make 8 tons of ReB2 a year, ignoring Gregg's volumetric inequalities for the present, giving a raw material cost for Rhenium alone of roughly eighty-million dollars. At this level our fictious company would consume roughly sixty percent of the current world production of Rhenium and would certainly drive the price up until limiting production to significantly below our target volume.
Ok, there is my straw-man. Let'r rip.
starbolin
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snipped-for-privacy@sbcglobal.net wrote:

As with all things, it depends. If it will do hard ferrous alloys it will easily command a c-BN price in those applications. Turbine blades must be formed and polished. If the NASA or the DoD finds a nice use cash will flow (e.g., hafnium diboride strakes on warhead reentry modules). Rhenium annual production is pegged to use.
A bunch of guys diddling in lab is not a production environment. Let it ride, see what happens. If there is a sustained important use attended by profits there will be a source. Things will get better over time if somebody can divert management.
Let it ride, see what happens.
Stoichiometric carbon nitride, C3N4, was all over the literature for a year for being theoretically harder than diamond. We made a model of its proposed crystal structure. It looked like a dog to us. We considered engineer-proposed bulk syntheses. Those also looked like dogs - real howlers. Rules for making stuff under geodynamic conditions are not all that difficult: If anything heavier than hydrogen has to move much in a solid, you're screwed. It would have been no big deal to make suitable C,N stoichiometric dendrimer precursors with C3N4 formation driven by two kinds of volume collapse. Microscopic pseudoadiabatic heating is always interesting (e.g., hollow glass microballoons in aqueous gel explosives). The very minor hydrogen component would have diffused out.
We put in our $0.02 as chemists. Engineers wiped their hands and returned to failing, by the book. They failed mangnificently while burning so many beautiful hours of geodynamic press time looking for steep maxima on a flat surface. When you have nothing, a new idea from a different perspective is the best chance you have. It cannot do worse than what you currently hold.
The same for growing diamond by chemical synthesis from condensed medium at ambient pressure. CVD works. Why not do it at 1000X plasma density for 1000X deposition rate? The chemistry is... obvious. One simply discards what cannot/will not work and sees what remains, if anything, at the bottom of Pandora's lunchbox. There is something and we are pursuing it until we usefully obtain product or exhaust being clever. Apparatus and consummables cost piffle - a chemist is in charge. Chemists are simple beings who don't get weekends at the club. We have no fear. We have waste crocks.
The same for violating the Equivalence Principle. Does all matter vacuum free fall identically? Certainly all chemical compositions and associated variables (nuclear binding energy, spin, etc., all the way to the Nordtvedt effect) fall identically, including neutron stars. Is spacetime geometry divergently interactive with mass distribution geometry (chirality)? That sounds interesting to a chemist. That has profound basis in orthodox physical theory. Quantitative geometric parity divergence is rigorously derived and calculated. Reduction to practice is no more expensive than anything else these guys do. They cannot see into an ORTEP stereogram, they will not consider outside suggestion despite 420+ years of perfect failure.
We are pursuing the chemical approach and will know that answer after 3 mm diameter benzil crystals are grown from solution (melt growth won't do given lattice disorder neuron diffraction data),
http://www.mazepath.com/uncleal/lajos.htm#a2
Adelberger at U/Wash and Newman at UC/Irvine are sitting on the world's most exquisite Eotvos balances. Newman default uses solid spheres as test masses - our optimum. Neither one will consider oppposite parity mass distributions - single crystal space group 3(1)21 vs. P2(2)21 alpha-quartz. Christ in Hell, they have no concept of a crystal lattice at all and think chirality is threaded machine screws. I've done face time.
No biggie. There is another way to motivate them. After all... universities are professionally managed.
Rhenium diboride is still being born. If it comes out with horns and hooves and breathing fire, it will do OK whatever the cost and bulk availability.
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Uncle Al
http://www.mazepath.com/uncleal/
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Woa! Lots a big words there Al. Don't wear out your dictionary.

Stop the presses! Rhenium is abundant! Need more Rhenium? Just order it up.
Actually Rhenium is a trace element in Molybdenum ores which are themselves rarer than gold.

"Rhenium compounds are included in molybdenum concentrates derived from porphyry copper deposits, and rhenium is recovered as a byproduct from roasting such molybdenum concentrates."
Rhenium ran up from $1170 per kg to $5000 per kg in 2006 after shipments from mines in Kazakhstan were blocked by a legal despute. This in spite of the Kazakhstan supplying only 18% of world production. Domestic sources are estimated to be near maximum capacity so we can't expect help from there. Any increase in Rhenium useage is going to increase prices.
I'm not saying that the DoD can't line it's missle tips with it. I just don't see ReB2 being a large factor in the industrial markets as compared to CBN or diamonds.
starbolin
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"Richard J Kinch" < snipped-for-privacy@truetex.com
| "A super-hard material that is tough enough to scratch diamond could be | made cheaply and easily, a new study suggests. The material is made from | the metal rhenium and the element boron and resembles both a metal and | a crystal in structure." | | http://www.newscientisttech.com/article/dn11670-supertough-material-mimics-metal-and-crystal.html
----------- I have taken the liberty of extracting this from the Science article :
Science 20 April 2007: Vol. 316. no. 5823, pp. 436 - 439 DOI: 10.1126/science.1139322
REPORTS Synthesis of Ultra-Incompressible Superhard Rhenium Diboride at Ambient Pressure Hsiu-Ying Chung,1,2* Michelle B. Weinberger,1* Jonathan B. Levine,1 Abby Kavner,3 Jenn-Ming Yang,2 Sarah H. Tolbert,1 Richard B. Kaner1,2
The quest to create superhard materials rarely strays from the use of high- pressure synthetic methods, which typically require gigapascals of applied pressure. We report that rhenium diboride (ReB2), synthesized in bulk quantities via arc-melting under ambient pressure, rivals materials produced with high-pressure methods.
Microindentation measurements on ReB2 indicated an average hardness of 48 gigapascals under an applied load of 0.49 newton, and scratch marks left on a diamond surface confirmed its superhard nature. Its incompressibility along the c axis was equal in magnitude to the linear incompressibility of diamond. In situ high-pressure x-ray diffraction measurements yielded a bulk modulus of 360 gigapascals, and radial diffraction indicated that ReB2 is able to support a remarkably high differential stress. This combination of properties suggests that this material may find applications in cutting when the formation of carbides prevents the use of traditional materials such as diamond.
The design of superhard materials is motivated by a need for robust, chemically diverse compounds for industrial applications ranging from abrasives and cutting tools to scratch-resistant coatings. Although diamond, with the highest known hardness (70 to 100 GPa), has traditionally been used to fulfill many of these needs, there are limits to its applicability. For example, diamond is not used to cut steel and other ferrous metals because of the detrimental formation of iron carbide during high-speed machining. Therefore, there is a need for synthetic materials that can be used in place of diamond. Cubic boron nitride (BN), the second hardest material (45 to 50 GPa), is used to cut steel because iron borides and nitrides are much less stable. However, cubic BN must be synthesized under extreme pressures (>5 GPa) and temperatures (>1500C), making it expensive (1). Two other compounds that have been synthesized recently, B6O (2) and cubic BC2N (3), rival the hardness of cubic BN. However, their syntheses also require extreme pressures, exceeding 5 GPa for B6O and 18 GPa for BC2N.
Our approach to creating ultra-incompressible superhard materials has been to optimize two design parameters: high valence-electron density and bond covalency (4, 5). High electron densities can be found among the later transition metals, whereas small first-row main-group elements, such as B, C, and N, form the strongest covalent bonds (6). Among the transition metals, Os has the highest valence-electron density (0.572 electrons/3) and a reported bulk odulus between 395 and 462 GPa (79) that rivals that of diamond (442 GPa) (10, 11). However, unlike diamond, the hardness of Os metal is only 4 GPa. This can be explained by the nondirectional metallic bonding in Os versus the short, highly covalent, directional bonds formed by sp3 hybridized C atoms in diamond. The strength and directionality of covalent bonds limit the creation and propagation of defects, which in turn causes diamond to resist plastic deformation, resulting in diamond's exceptional hardness. By optimizing covalent bonding and valence- electron density, we recently succeeded in designing, synthesizing, and characterizing an ultra-incompressible hard material, OsB2 (4). In searching for even harder materials, we looked closely at the elements surrounding Os in the periodic table. Re, which lies directly to the left of Os, has a slightly lower alence- electron density (0.4761 electrons/3) that produces a similar bulk modulus of 360 GPa (12). Despite being highly incompressible, the hardness of Re metal is also low, between 1.3 and 3.2 GPa, because of its delocalized nondirectional metallic bonding (13, 14). Incorporating B into the interstitial sites of Re to form ReB2 requires only a 5% expansion of the Re lattice. This results in the shortest metal-metal bonds of any known transition-metal diboride (15). In contrast, the Os lattice expands by approximately 10% upon the incorporation of B atoms to form OsB2 and undergoes a distortion to an orthorhombic phase. Applying our design criteria, ReB2 is thus considered to be the most likely candidate for improving on the mechanical properties of OsB2. ReB2 has the highest B:Re ratio among the known RexBy phasesRe3B, Re7B3, and ReB2 (16)and therefore contains the greatest degree of covalent bonding. The structure of ReB2 consists of alternating layers of hexagonal close-packed Re and puckered hexagonal networks of B (Fig. 1). The result is a compound that is layered perpendicular to the c axis along the (00l) planes. Recent theoretical calculations have shown that there are strong covalent B-B and Os-B bonds in OsB2 (1720). By analogy, ReB2 should contain similar covalent B-B and Re-B bonds, with the Re-B bonds in ReB2 expected to be shorter and stronger than those in OsB2 because of the minimal lattice expansion.
ReB2 was synthesized under ambient conditions via three methods, each of which may potentially be scaled up (supporting online text). First, a solid-state metathesis reaction was carried out between the metal trichloride and MgB2, because this process has been used to produce many transition-metal diborides, including OsB2 (4, 21). Without excess B, however, this process forms multiple boride phases. Second, Re and B powders were mixed together, pressed into a pellet, and then liquefied with 80 amps of current in an Ar atmosphere. The result was a solid metallic ingot of ReB2 that could be used for hardness testing. In the third method, stoichiometric quantities of Re and B powder were sealed in a quartz tube under vacuum and heated for 5 days at 1000C. Powder x-ray diffraction, performed on a crushed portion of both the arc-melted ingot and the polycrystalline powder produced from the elements, confirmed the synthesis of phase-pure ReB2 (fig. S1). These materials were then examined by microindentation and in situ high-pressure x-ray diffraction techniques.
The covalent bonding that results in high hardness values can also contribute to the elastic incompressibility (bulk modulus) of a material. To further explore the contribution of covalent bonding as well as the possible correlation between valence-electron density and bulk elastic properties, data on the elastic volume compressibility of ReB2 were collected via in situ high-pressure x-ray diffraction studies. Samples were compressed quasi-hydrostatically up to 30 GPa in a diamond anvil cell, and in situ diffraction data were collected under pressure. From the diffraction data, the fractional volume at increasing pressures was calculated. Fitting the pressure/volume (P versus V /V0) data with a third-order Birch-Murnaghan equation of state, the bulk modulus of ReB2 was determined to be 360 GPa when Bo' (derivative of the zero-pressure bulk modulus with respect to pressure) was fixed at the canonical value of 4. This high bulk modulus is in agreement with our understanding of the correlation between valence-electron density and incompressibility (4, 6). In addition to bulk volume compressibility, the high-pressure diffraction data also revealed an anisotropy in the compressibility of the two different lattice directions of hexagonal ReB2 (Fig. 3). As seen in Fig. 3, the c axis is substantially less compressible than the a axis, and this c axis value is very similar to the analogous linear compressibility of diamond. This anisotropy results from greater electron density, and therefore greater electronic repulsions, along the c axis.
Having observed that the different planes of ReB2 are able to support varying amounts of stress in the conventional and radial geometry high-pressure experiments, we anticipated observing this effect in our hardness measurements as well. Indeed, Fig. 2A shows that there is a substantial difference between the highest and lowest measured hardness across grains of ReB2 under the same load. This observed spread in hardness values at constant load can be attributed to the anisotropic structure of ReB2, combined with our inability to control the crystallographic orientation of the tested grains. For example, under a load of 4.9 N, the highest measured hardness is 32.5 GPa and the lowest obtained value is 26.0 GPa. We can begin to understand this variation in hardness by using electron backscattering diffraction to measure the orientations of the grains studied (Fig. 2, C and D). The results indicate that indentations parallel to the (00l) planes yielded the lowest average hardness, a value of 27 GPa. In contrast, indentations along directions that contained a larger component parallel to the c axis [that is, perpendicular to (00l)] resulted in measurements with an average hardness of 31 GPa, an increase of 15%. The dependence of hardness data on crystallographic orientation can be explained by the presence of the same slip planes described above. Furthermore, because similar anisotropic behavior is observed in the high-pressure data, we conclude that the radial diffraction study elucidates the plastic behavior of the material, giving an indication of the yield strength rather than merely measuring elastic behavior.
In our microindentation experiments to date, we have found no grains with pure (00l) orientation. As a result, our data demonstrate a minimum average hardness. It is likely that these planes parallel to (00l), which we were unable to directly measure, will have an even higher hardness and are responsible for scratching diamond (Fig. 2B).
References and Notes
donald j haarmann ---------------------------- The turbo-encabulator in industry.
For more then 50 years the Arthur D. Little Industrial Bulletin has endeavored to interpret scientific information in terms that he lay person could understand. "The turbo-encabulator in industry" is the contribution of J.H. Quick, graduate member of the Institution of Electrical Engineers in London, England, and was, first published in the Institution's Students' Quarterly Journal in December 1944, It is here reprinted without the kind permission of that publication and of the author in a further salute to Quick.
For a number of years now, work has been proceeding to bring perfection to the crudely conceived idea of a machine that would not only supply inverse reactive current for use in unilateral phase detractors, but would also be capable of automatically synchronizing cardinal grammeters.
Such a machine is the "turbo-encabulator." Basically, the only new principle involved is that instead of power being generated by the relative motion of conductors and fluxes, it is produced by the medial interaction of magneto-reluctance and capacitive directance.
The original machine had a base plate of prefabulated amulite, surmounted by a malleable logarithmic casing in such a way that the two spurving bearings were in direct line with the pentametric fan. The latter consisted simply of six hydrocoptic marzelvanes, so fitted to the ambifacient lunar waneshaft that side fumbline was effectively prevented. The main winding was of the normal lotus-0-delta type placed in panendermic semiboiloid slots in the stator, every seventh conductor being connected by a nonreversible tremie pipe to the differential gridlespring on the "up" end of the grammeters.
Forty-one manestically spaced grouting brushes were arranged to feed into the rotor slipstream a mixture of high S-value phenylhydrobenzamine and 5% remanative tetryliodohexamine. Both of these liquids have specific pericosities given by P=2.5C.n(exponent)6.7 where n is the diathetical evolute of retrograde temperature phase disposition and C is Chlomondeley's annular grillage coefficient. Initially, n was measured with the aid of metaploar refractive pilfrometer (for a description of this ingenious instrument, see Reference 1), but up to the present, nothing has been found to equal the transcendental hopper dadoscope (2).
Electrical engineers will appreciate the difficulty of nubing together a regurgitative purwell and a supramitive wennelsprock. Indeed, this proved to be a stumbling block to further development until, in 1942, it was found that the use of anhydrous nangling pins enabled a kryptonastic boiling shim to the tankered.
The early attempts to construct a sufficiently robust spiral decommutator failed largely because of a lack of appreciation of the large quasipiestic stresses in the gremlin studs; the latter were specifically designed to hold the roffit bars to the spamshaft. When, however, it was discovered that spending could be prevented by a simple addition to the living sockets, almost perfect running was secured.
The operating point is maintained as near as possible to the h.f. rem peak by constantly fromaging the bitumogenous spandrels. This is a distinct advance on the standard nivel-sheave in that no dramcock oil is required after the phase detractors have remissed.
Undoubtedly, the turbo-encabulator has not reached a very high level of technical development, It has been successfully used for operating nofer trunnions. In addition, whenever a barescent skor motion is required, it may be employed in conjunction with a drawn reciprocating dingle arm to reduce sinusoidal depleneration.
References
(1) Rumpelvestein, L.E., Z. Elektro-technistatisch-Donnerblitz vii. (2) Oriceddubg if the Peruvian Academy of Skatological Sciences, June 1914.
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