Showing papers on "Diamond published in 1981"

Well drilling tool with diamond radial/thrust bearings

Abstract: A turbodrill is disclosed for connection to a drill string and has a rotating shaft for turning a drill bit. The turbodrill has rotor and stator blades operated by drilling mud flowing therethrough to rotate the shaft. The shaft is provided with radial/thrust bearing consisting of a pair of annular plates, each of which has conical surfaces supporting a plurality of friction bearing members of polycrystalline diamond. The radial and thrust loads are carried by the wear-resistant diamond bearing surfaces. The bearing members are preferably cylindrical studs having flat faces with flat disc-shaped diamond bearing members supported thereon around the adjacent surfaces of the supporting plates. The faces of the diamond bearings will wear into smoothly mating conical bearing surfaces with use. There are two or more pairs of diamond radial/thrust bearings to handle longitudinal as well as radial loads. The use of the diamond radial/thrust bearings makes it possible to eliminate the lubricant-flooded construction of prior art turbodrills and allow the bearings to be cooled and lubricated be drilling fluid flowing therethrough. The diamond radial/thrust bearings may be used with lubricant-flooded turbodrills and with other types of downhole motor driven drills such as drills driven by positive displacement motors.

Manufacture of diamond bearings

Abstract: In the manufacture of diamond bearings consisting of a supporting plate/ring having a plurality of recesses equally spaced therearound with insert members consisting of hardmetal or carbide studs, with planar faces of polycrystalline diamond, positioned therein, the diamond bearing faces are made co-planar by placing metal pads, preferably of brazing metal, in the bottom of each recess before insertion of the bearing studs, placing the assembly with the bearing faces on a smooth planar support, heating the assembly to a temperature at which the metal pads soften or melt and allowing the metal pads to extrude around and braze the bearing inserts in place. When the assembly has cooled, the bearing inserts have their diamond bearing faces locked in co-planar relation by the extruded metal from the metal pads.

Raman efficiency measurements of graphite

Abstract: The Raman efficiency of graphite, germanium and silicon have been measured at room temperature with 5145 A laser excitation The efficiencies were determined from a comparison with the 1332 cm−1 zone center phonon of diamond For graphite, the 1585 cm−1 E2g intralayer mode was studied, while for Si and Ge the 525 cm−1 and 303 cm−1 F2g zone center modes were measured

The Jahn-Teller effect and vibronic coupling at deep levels in diamond

Abstract: Reviews the vibronic properties of point defects (i.e. impurities and radiation-induced defects) in diamond. Cases discussed are: defects where the totally symmetric electron-lattice interaction dominates; cases of dynamic Jahn-Teller distortions; vibronic interactions between nearly degenerate states and a statically deformed defect. Before discussing each of these topics the relevant theory is outlined at an introductory level with the emphasis on features relevant to understanding data. It is shown that a good understanding of the vibronic data is now available in diamond. Compared to defects in silicon, defects in diamond are less prone to static deformations, partly as a result of the high-energy transverse acoustic modes in diamond.

Compound sintered compact for use in a tool and the method for producing the same

Abstract: The invention enables to obtain a compound sintered compact for use in a cutting tool having particularly high properties in respect of bonded strength, hardness, wear resistance, plastic deformability and rigidity by bonding a diamond or cubic boron nitride containing hard layer to a cemented carbide substrate with interposition of an intermediate bonding layer. A powder for forming the intermediate bonding layer comprising cubic boron nitride in an amount less than 70 volume %, the residual part principally consisting of a compound selected from among carbides, nitrides, carbonitrides or borides of 4a, 5a, 6a transition metals of the periodic table, an admixture thereof, or a mutual solid solution compound thereof, after pressing or in the state of powder, is placed on the cemented carbide substrate to a thickness less than 2 mm, or preliminarily applied to said cemented carbide substrate, further on said powder being placed a powder for forming the hard sintered compact containing diamond or cubic boron nitride in an amount in excess of 20 volume % after pressing or in the state of powder, the whole being hot pressed under an ultrahigh pressure and a high temperature to sinter the diamond or cubic boron nitride containing hard layer and the intermediate layer as well as to bond said hard layer, intermediate layer and substrate to each other, thereby enabling to obtain a compound sintered compact having the aforesaid superior properties for use in a cutting tool.

Rotary drill bit

Abstract: Cutting elements, for example of polycrystalline sintered diamond, the cutting faces of which are set differently to the cutting direction, are disposed on a rotary drill bit. One group of cutting elements has its cutting faces substantially perpendicular to the cutting direction (straight set cutting elements) while other groups of cutting elements are at an acute angle to the cutting direction (obliquely set cutting elements). Because of their greater pressure per unit area, the obliquely set cutting elements penetrate more easily into plastic formations and can tear these up. The straight set cutting elements, which do not develop a great pressure per unit area, but work over a wider range, can better pare off the formation prepared by the obliquely set cutting elements.

Polycrystalline diamond and cemented carbide substrate and synthesizing process therefor

Abstract: A polycrystalline diamond body infiltrated by a silicon atom-containing metal (e.g., silicon alloy) is bonded to a substrate comprising cemented carbide with a barrier of refractory material extending between the diamonds cemented together with silicon atom-containing binder and the substrate substantially precluding migration of the cementing medium (e.g., cobalt) from the carbide substrate into contact with the silicon atom-containing bonding medium in the diamond body. The process comprises subjecting a mass of diamond powder, a quantity of silicon atom-containing metal binder material, a cemented carbide body and a barrier made of material selected from the group consisting of tantalum, vanadium, molybdenum, zirconium, tungsten and alloys thereof to the simultaneous application of elevated temperature and pressure.

Dosimetry with a diamond operating as a resistor.

Abstract: A very pure diamond with contacts of graphite has a linear current-voltage characteristic when subjected to irradiation. The resistivity is inversely proportional to the dose rate and the sensitivity is extremely high for gamma - and X-rays and electron beams. It is concluded that diamond resistors are suitable for clinical radiation dosimetry. This conclusion is also based on earlier work in which diamonds were used as pinpoint counters.

Strength and fracture properties of diamond

Abstract: The strength of diamond is usually measured using an indentation technique. It is shown that the values obtained by previous workers for good quality diamond are reasonably consistent if they are all calculated with the same chosen values of modulus and Poisson ratio. By monitoring the extent of crack growth from beneath a loaded indenter it has been possible to measure the fracture surface energy, γ, of diamond (5·50 ± 0·15 Jm−2) and from this calculate the critical stress intensity factor KIC (3·4MN m−3/2). The significance of the measured γ compared with the theoretical value for the surface energy of 5·3 J m−2 for (111) cleavage is discussed. The strengths of various types of diamond grit particle have been measured by loading single particles between hard anvils. It is shown that there is a strength/size effect with smaller particles giving higher strengths. A linear relation between load and particle diameter suggests that Auerbach's Law holds for diamond in the size range covered. Some syn...

The frictional anisotropy of diamond

Abstract: This paper describes a study of the friction, in air, of a spherically tipped diamond stylus over the {100} face of a flat diamond surface. The results show that in general the friction is greater when sliding occurs along the direction than along the direction. This cannot be explained in terms of a Coulomb frictional mechanism where the friction is attributed to the climbing of one surface over the asperities on the other, for in that case the coefficient of friction is determined solely by the surface topography and is independent of load. By contrast, the experiments described in this paper show that below a critical load Wc the frictional anisotropy virtually disappears. This critical load is proportional to R 2 , where R is the radius of curvature of the stylus, implying, for Hertzian deformation, a critical contact pressure. For both type I and type II diamonds this critical pressure has a value of the order of 20 GN m -2 . At these and larger contact pressures cathodoluminescent studies of the flat diamond surfaces indicate that the frictional anisotropy is largely due to surface and sub-surface damage produced in preferred crystallographic directions by the sliding process itself. The results are discussed in terms of crack formation and plastic deformation. However, the results do not, as yet, provide an unequivocal account of the mechanism of energy dissipation.

Electrical resistivity measurements of conductors in the diamond‐window, high‐pressure cell

Abstract: The electrical resistance measurement of metallic conducting materials can be done in situ in a diamond‐window, high‐pressure cell with a four‐lead arrangement designed to avoid contact and lead‐wire resistances. Variants of the general method include designs for long (several cm) and short (less than 1 mm) length of samples material, and for the use of solid and fluid pressure‐transmitting media.

Infrared refractive index of diamond

Abstract: The refractive index of natural Type IIa diamond is reported for the spectral region 2.5–25 μm. The data have been fitted to a Herzberger-type dispersion formula with a quality of fit of a few places in the fifth decimal place. The resultant index uncertainty is about 10−3.

Diamond anvil high-pressure cell for Raman spectroscopy

Abstract: A design of a diamond anvil cell is described where a single crystal of sapphire is used for the backing of one anvil with the advantage of an enlarged aperture at an extended pressure range The selection of diamond anvils with low luminescence at excitation with the Argon Ion laser is discussed Procedures to control the stresses in samples at very high pressures are given and illustrated by Raman spectra of D2O

The stages of nitrogen aggregation in diamond

Abstract: An experiment is described in which a synthetic diamond containing a high concentration of dispersed nitrogen atoms was heated at 2400 degrees C and 2500 degrees C under a stabilising pressure of about 9.5 GPa. The nitrogen atoms aggregated to form the types of nitrogen centres which are found in natural type 1a diamonds. Of particular interest was the formation of platelets in the cube planes. The results strongly suggest that the platelets were mainly composed of nitrogen atoms.

Electron spectroscopy of the diamond surface

Abstract: The diamond surface is studied by ionization loss spectroscopy and Auger electron spectroscopy. For surfaces heated to temperatures not exceeding 900 C, the band gap was found to be devoid of empty states in the absence of electron beam effects. The incident electron beam generates empty states in the band gap and loss of structure in the valence band for these surfaces. A cross section of 1.4 x 10 to the -19th sq cm was obtained for this effect. For surfaces heated to temperatures exceeding 900 C the spectra were identical to those from surfaces modified by the electron beam. The diamond surface undergoes a thermal conversion in its electronic structure at about 900 C.

Synthesizing method for diamond

Abstract: PURPOSE:To synthesize granular or filmlike diamond stably by introducing a gaseous mixture of gaseous H2 passed through the inside of microwave nonpolar discharge and hydrocarbon into the surface of a substrate heated to specific temps. and thermally decomposing the hydrocarbon. CONSTITUTION:After a reacting system is evacuated to 0.05-400Torr by driving an evacuating device 6, the gaseous H2 in a supply device 2 is passed through the inside of the microwave nonpolar discharge generated from a waveguide 4 by a microwave oscillator 3 to grow H in an excited state or atomic state. The H is mixed with hydrocarbon (e.g.; methane) supplied from a supply device 1 and the mixture is introduced into a reacting chamber 5, where the mixture is supplied onto the surface of a substrate 7 on a susceptor 9 heated to 300- 1,300 deg.C by a resistance heating furnace 9, whereby the hydrocarbon in the excited state is thermally decomposed and diamond is deposited. Thus the control of nucleus forming speed is facilitated and the granular or filmlike diamond is synthesized easily.

Damage and lattice location studies in high‐temperature ion‐implanted diamond

Abstract: The results of implantation of various ions (Li,C,P,Ge, and Sb) into heated diamond (∼1000 °C) are studied by channeling techniques. The residual damage and the locations in the lattice, which the implants occupy, are determined. It is shown that by implanting into heated diamond (i) graphitization can be avoided and (ii) an appreciable fraction of Li ions can be driven into interstitial sites where they are expected to be electrically active donors.

Hybrid diamond insert platform locator and retention method

Abstract: This concept discloses a new technique which uses brazing or diffusion bonding methods to attach a diamond disk to a wedge-shaped steel support platform on a hybrid type of bit. The invention is primarily concerned with the attachment of the innermost diamond cutting disk on the wedge-shaped drag bit face portion of the hybrid bit. It is particularly difficult to secure any kind of cutting structure to the innermost portion of a rock bit because of the lack of material available to secure the cutting structure to the drag bit face. Space limitations on the drag bit face prevent the use of conventional interference fit diamond insert studs for the innermost cutters.

Aggregation of Nitrogen in Diamond, Including Platelet Formation

Abstract: Nitrogen occurs in most natural diamonds in concentrations of up to 0.3 at. %. In about 0.1% of diamonds, the nitrogen occurs as single substitutional atoms but in most diamonds aggregates of two or more nitrogen atoms occur. The various types of aggregate have been identified by detailed study of optical absorption spectra and by other methods. This paper describes experiments in which synthetic diamonds, containing substantial quantities of nitrogen in the form of single substitutional atoms, have been heated to cause aggregation. All the aggregates found in natural diamonds have been produced under controlled conditions of temperature and pressure. Of particular interest has been the formation of platelets which are found in type 1 natural diamonds in the {100} planes. Several experiments suggest strongly that these platelets are large aggregates of nitrogen atoms. To obtain aggregation in a reasonable time, the mobility of the nitrogen atoms was increased by irradiating the diamonds with 2 MeV electrons before heating. This irradiation produced numerous vacancies and interstitial atoms in the diamond lattice. Even so, temperatures of up to 2200°C were necessary to produce the required rapid motion of the nitrogen atoms. To prevent graphitization of the diamond at these temperatures, the specimens were subjected to a pressure of 8.5 GPa during the heating. The experiments establish the sequence of the aggregation of nitrogen atoms in diamond and are relevant to the understanding of the conditions under which aggregation occurred in natural diamonds. It seems probable that, for some diamonds at least, the interval between their formation and their ejection to the surface of the earth was very short on a geological time-scale.

Diamond Synthesis in Cool Plasma

Abstract: The conditions of low pressure autoepitaxy of diamond are analysed and theoretical concepts concerning the plasmochemical method of diamond synthesis put forward. The experimental method used is described. The obtained results have demonstrated the utility of the plasmochemical method for obtainment of diamond and confirmed the validity of the presented theoretical concepts. Die Bedingungen fur die Autoepitaxie von Diamant bei niedrigen Drucken wurden analysiert und theoretische Erwagungen uber die plasmochemische Diamantsynthese dargelegt. Die Untersuchungsergebnisse haben die Nutzlichkeit der plasmochemischen Methode fur die Synthese von Diamant als auch die grundsatzliche Gultigkeit der dargelegten theoretischen Erwagungen erwiesen.

Volume expansion of ion‐implanted diamond

Abstract: Boron implantation into diamond at room temperature leads to significant irreversible volume expansion when the boron dose exceeds 5×1015 cm−2. This observation is presumed to reflect an upper limit in the extent to which diamond can be effectively doped with boron by ion implantation. Similar limitations associated with other implant species are anticipated.