Abstract: Coolant recirculation arrangement for a nuclear reactor including a plurality of vertically oriented tubular conduits arranged in spaced relation between an unshrouded nuclear core and the inner pressure vessel wall for conducting coolant from an upper plenum above the core to a lower plenum below the core.

Abstract: Disclosed is a method for making re-sintered polycrystalline CBN compact which comprises placing sintered boron-rich polycrystalline CBN particles in a high temperature/high pressure apparatus and subjecting said boron-rich CBN particles to a pressure and a temperature adequate to re-sinter said particles, the temperature being below the reconversion temperature of CBN, for a time sufficient to re-sinter the polycrystalline CBN particles therein. The boron-rich polycrystalline CBN particles in the HP/HT apparatus contain no impurity which would interfere with the sintering process (CBN sintering inhibiting impurities) and no sintering aid material.

Abstract: Disclosed is a composite abrasive particle comprising a core abrasive crystal and a silicon carbide coating inherently bonded to substantially all of the exterior surfaces of said core crystal, said silicon carbide coating characterized by silicon carbide crystals having a random orientation substantially independent of the structure of the core crystal, the outer surface of the coating being conformationally irregular. Aggregates of the composite abrasive particles are interconnected by a matrix of silicon carbide which has an open structure. Preferred core abrasive crystals are diamond or cubic boron nitride.

Abstract: Optical windows for hostile environments have been made from diamond and adamantine boron nitride compacts. The compact windows can comprise a single layer of large crystals bonded in a matrix. For example, they are made by exposing a sample of diamond (425-1700 micron) in a diamond and graphite matrix to high pressure-high temperature conditions (e.g., 50 Kbar at 1400.degree. C. to 85 Kbar at 1800.degree. C.).A typical boron nitride reaction zone assembly (cell) is shown in FIG. 1, in which carbon heater tube 1 is surrounded by tantalum foil sleeve 2. The sample of pyrolytic boron nitride 3 is disposed between carbon discs 5, tantalum foil discs 4 and hot pressed boron nitride plugs 6.The optical windows produced are capable of transmitting infrared light and visible light.

Abstract: A process improvement is disclosed for making diamond wire die compacts of the type which are generally described as an inner polycrystalline diamond mass surrounded by and bonded to a mass of metal bonded carbide, such as cobalt cemented tungsten carbide. It is known to make these dies by high pressure-high temperature processes, typical conditions being 50 kbar and temperatures in excess of 1300.degree. C. The improvement comprises disposing within the reaction sub-assembly (e.g. metal carbide and diamond within a zirconium cup) a set of discs of specific materials in specified arrangements. For example, on one side of the mass of metal carbide and diamond is disposed one disc of a diamond catalyst/solvent and one disc of a refractory metal such as molybdenum, and on the other side are disposed at least two discs of one or more transition metals such as zirconium. These discs are generally placed inside the sub-assembly cup.

Abstract: Disclosed is an improved implement comprising a cemented carbide supported composite abrasive compact which is brazed to a cemented carbide substrate with a brazing filler metal having a liquidus substantially above 700.degree. C. The composite compact preferably is a composite polycrystalline diamond compact. The brazing filler metal is a brazing alloy having a liquidus not substantially above 1,004.degree. C. and which has the following composition, by weight:Au: 18-39.5%Ni: 3.5-14.5%Pd: 2.5-10.5%Mn: 7.5-9.0%Cu: Balance.

Abstract: The high pressure/high temperature (HP/HT) process for making diamond or CBN compacts has been modified by placing partitions within the crystal mass before HP/HT processing. With reference to FIG. 3, within the shield metal sleeve 11 and shield metal cup 14 are placed pliable metal shapes 20 in a honeycomb pattern. The abrasive crystals within the tubes 18 and outside the tubes 26 is sintered, and a compact containing the tubes embedded therein results. This compact can be acid leached to give a plurality of small compacts which need little if any additional shaping. The partitions can also be left intact as chip arresters.

Abstract: Disclosed is an improvement in method for both dry grinding and wet grinding a workpiece selected from cemented tungsten carbide and combinations of cemented tungsten carbide and steel with a single resin bonded grinding element having metal-coated diamond particles embedded in the grinding surface thereof. Such improved method comprises providing coated diamond particles useful for both dry grinding and wet grinding operations which comprises diamond coated particles coated with two layers of metal, the inner layer consisting of between about 40% and 130% by weight of said diamond particle of nickel and the outer layer consisting of between about 20% and 70% by weight of said diamond particle of silver, wherein the total weight of both said silver and nickel coatings does not exceed above about 200% by weight of the uncoated diamond particle.

Abstract: The high pressure/high temperature catalyst sweep through process for making diamond and cubic boron nitride compacts has been improved by adding an intermediate metal or metal alloy. The added metal (whether alone or contained in an alloy) has a melting point below that of the catalyst (e.g. cobalt), is miscible with the catalyst, and preferably sweeps through the mass of abrasive crystals first. This modification has reduced flaw formation in such compacts.

Abstract: An improved vertical gang saw is provided for sawing blocks of stone or the like. By this new design, the vertical saw frame is slued or swung about the center of the blades during each reciprocating movement. This design combines the following features:(a) the vertical frame (5) being supported at the center (13);(b) straight line guides (6 and 7) connected to said frame and positioned respectively at one end (21) and in the center (13) of the saw frame (5); and(c) the pivotal point of the straight line guide (6) being moveable perpendicular to the stroke of the frame and dependent thereupon.The perpendicular movement of the straight line guides can be accomplished by connecting them with a cam (10) which is driven off of the flywheel (3). Through this combination, all of the saw blades cut the stone block workpiece in both the up and down directions.

Abstract: A dressing method has been devised for plated grinding wheels having relatively coarse mesh microcrystalline cubic boron nitride abrasive. The method comprises lightly grinding cemented metal carbide (e.g. cobalt cemented tungsten carbide) with the grinding wheel before grinding the intended workiece. Wheels dressed in this manner have been found to obtain good surface finishes (16-18 RMS) while maintaining a free cutting aggressive action which gives high grinding rates.

Abstract: A process improvement is disclosed for making compacts containing diamond which reduces crystal flaws within the diamond. This is accomplished by isolating the single diamond crystals in an compressible matrix before exposing the sample to sintering conditions. One method for doing this (described with reference to FIG. 1) is embedding the diamond 14 in a mixture 16 of graphite and diamond fines. This mixture is disposed between two graphite discs 18 and 19 and two cobalt discs 22 and 23. This sub-assembly is contained within zirconium cup 10 on top of which is placed zirconium disc 12 and exposed to high pressure-high temperature sintering conditions.

Abstract: Disclosed is an improved fixture assembly for use on an electrode wire EDM apparatus which is adapted to cut a conductive workpiece. Referring to FIG. 2, the improved fixture which can secure a plurality of workpieces 52 comprises master bar 40, which is secured to work supports 30 transversely therebetween, base plate 42 which is removably attached to the master bar at a predetermined location thereof and which has a plurality of equally-spaced support locations upon which each said workpiece rests, locator plate 44 which is removably attached to the base plate at a predetermined location thereof and which has a plurality of equally-spaced recesses of predetermined shape along an edge thereof for a side of each workpiece to be held thereagainst, and a plurality of pre-configured clamps 48 removably attached to the upper side of said locator plate which are tightenable to exert force against the top surface of each workpiece for securing the workpiece in a precise location for cutting.

Abstract: An improved metal coated abrasive is prepared with a controlled, rough textured surface, which surface has improved adherence to resinous materials when said coated abrasives are incorporated into resin bonded tools. Disclosed is a process for achieving this rough texture through a modification to the known electroless or autocatalytic techniques for coating abrasives with metals such as copper and nickel. The improvement comprises: interrupting the electroless coating process by passivating the surface one or more times; and then reactivating the passivated surface each time with a catalytic material whereby an array of preferential sites for metal deposition is obtained; and resuming normal electroless coating.

Abstract: Disclosed is an improved method for applying a coating of elemental silver on the exterior surfaces of diamond particles wherein an ammoniacal silver solution is mixed with the reducing solution and the diamond particles contacted with said mixture. The improvement of the present invention comprises agitating the ammoniacal silver solution containing said diamond particles sufficiently to suspend the particles therein and adding the reducing solution to the agitated ammoniacal solution at a metered rate adequate to produce a continuous grainy elemental silver coating on the diamond particles. A typical reducing solution is aqueous invert sugar.

Abstract: A vapor compression cycle device with variable thermal capacity is provided with a means and a method for controlling device capacity modulation and evaporator superheat. Multi-component working fluid liquid flow from each of a pair of accumulators in a closed circuit device is regulated either in response to sensed thermal demand or in response to sensed working fluid vapor superheat.

Abstract: A power plant includes a primary and a secondary power cycle, with the secondary power cycle including a thermal reservoir adapted for the absorption of heat rejected from the primary power cycle during the simultaneous generation of power from the secondary power cycle. Heat is withdrawn from the thermal reservoir during periods of reduced power demand, allowing latitude in the scheduling of heat rejection from the power plant.

Abstract: A device for detecting alkali metals in gas streams includes a conduit defining a gas-flow cavity and a metalliferous filament having a work function of at least 5.6 ev extending transversely through the flow path. A heater heats the filament to ionize the alkali metals being detected. A perforated ion-collection member surrounds the filament to define an ionization-collection region. A high-voltage (HV) source develops a HV electrical field within the region, thereby effecting neutralization of the ionized metals contacted with the collection member. An ammeter generates a signal in response to the neutralization and proportional to the rate thereof. A detection method which can be performed by the device is also described.

Abstract: An improvement in the fixed-bed pressure gasification of coal is described. The improvement includes removing at least a portion of the hydrocarbon (e.g., tar) from the raw gaseous fuel produced in the gasification process and introducing the the removed hydrocarbon directly into the interior of the coal bed below the devolatilization zone and at or above the maximum-temperature location in the bed.

Abstract: A process is described for both (i) quenching a fuel gas mixture including at least one gaseous hydrocarbon foulant (described more particularly herein) and (ii) removing at least a portion of the foulant without substantial formation of mist thereof in the gas mixture. The process includes contacting a flow of the gas mixture with a liquid jet spray of large droplets of a coolant mixture comprising liquid water and viscous liquid hydrocarbon. The contact is maintained for a sufficient period of time such that at least a portion of the foulant is liquefied and collected on the droplets. The droplets having foulant thus deposited thereon are removed from the treated gas mixture in a separation zone.