Diamond core

Drilhng. Glass is dtiUed with carbide or bonded-diamond dtiUs under a suitable coolant such as water or kerosene. Other drilling processes include a metal tube rotating about its axis (core drilling), an ultrasonic tool in combination with an abrasive slurry, or an electron beam. Tolerances less than 0.1 mm are readily obtained with diamond-core drilling and, if required, holes smaller than 25 )J.m-dia can be made with the electron-beam method. 

Diamond Bit Design. Diamond drill bit geometry and descriptions are given in Figure 4-144 [49]. Diamond core bit geometry and descriptions are given in Figure 4-145 [50]. 

Figure 4-145. Diamond core bit nomenclature [50]. (Courtesy Hughes Christensen.)...

Diamond Coring Technology, student manual, Christensen, Inc. 

Natural single-crystal diamond and carbonado can now be replaced in many industrial uses by sintered diamond tool blanks. Such tool blanks are available in disks and cores. The disks, or sectors of disks, consist of a thin (0.5—1.5 mm) layer of sintered diamond up to about 50 mm diameter on a cemented tungsten carbide-base block about 3—6 mm thick. Using diamond abrasive, such blanks can be formed into cutting tools of various shapes. Typical tool blanks are shown in Figure 9. The wire dies have diamond cores up to 10 mm in diameter and 10 mm in length, which are encased in a cemented tungsten carbide sleeve up to 25 mm in diameter. 

Figure 6.20 Active sites of phosphatases with a dimetallic diamond core.

Figure 6.21 Phosphatase model with dimetallic a diamond core.

Shu LJ, Nesheim JC, Kauffmann K, Miinck E, Lipscomb JD, Que L. An Fe2IV02 diamond core structure for the key intermediate Q of methane monooxygenase. Science. 1997 275 515-8. 

Xue G, Wang D, De Hont R, et al. A synthetic precedent for the [FeIV2(mu-0)2] diamond core proposed for methane monooxygenase intermediate Q. Proc Natl Acad Sci USA. 2007 104 20713-18. 

Hsu, H., Dong, Y., Shu, L.,Young, J., V. G., and Que, J., L., 1999, Crystal structure of a synthetic high-valent complex with an Fc2(p-0)2 diamond core. Implications for the core structures of methane monooxygenase intermediate Q and ribonucleotide reductase intermediate X, J. Am. Chem. Soc. 121 5230n5237. 

In MMO, compound Q has been identified as a coupled diiron(IV,IV) species, on the basis of its Mossbauer spectrum. While different structures for compound Q are possible, there is now some spectroscopic evidence (X-ray absorption fine structure and Mossbauer spectroscopy) that the diiron center in compound Q is a high-valent Fe2(/A-0)2 diamond core (Scheme 2). In the proposed mechanism, reaction... 

When the precursor to the Fe(III,IV) compound is [Fe 2(/r-0)2(6-Me3-TPA)2] +, one-electron oxidation affords a Fe k 0-Fe =0 core structure derived from the isomerization of the Fe2(/r-0)2 diamond core, demonstrating the accessibility of a terminal Fe =0 unit in a nonheme environment. A different approach to achieve the Fe(III,IV) unit has also been carried out by Lippard etal. In this method, a tetracarboxylate-bridged diiron(II,II) complex (4-t-BuPy)2Fe2(/r-RC02)4 where RC02 is the bulky carboxylate Ar C02 (Schemed) is exposed to dioxygen at -79°C. Among the products identified by Mossbauer and EPR spectroscopy is an Fe(III,IV) species. 

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