Abstract:
The invention relates to a method for producing magnesium diboride (MgB2) from magnesium hydride and compounds derived from magnesium diboride by replacing Mg with other metals or by replacing B with other non-metals. The invention also relates to the production of magnesium diboride moulded bodies.
Abstract:
A very-high pressure generator of construction such that the lower and upper guide blocks of the generator are each configured so as to form a pyramidal recess on the bottom surface and an upside-down pyramidal recess on the top surface accurately symmetrically, their pyramidal slopes given one and the same angle of inclination, and are prevented from being deformed under high pressure not by enlarging the guide blocks and the press, but by making the support conditions of all the anvils of the generator uniform, the positions of the anvils can easily be adjusted, and therefore the generator is capable of pressurizing a pressure-transmitting medium into the shape of a desired cube accurately. Each of the lower and upper guide blocks has a pyramidal recess in its bottom surface and an upside-down pyramidal recess in its top surface and is symmetric with respect to its horizontal center plane. Each of lower and upper base blocks has a lower upside-down pyramidal portion and an upper pyramidal portion. The upper base block is disposed at the center of the lower pyramidal recess of the upper guide block. An upper downward pyramidal block is disposed between the press frame and the upper upside-down pyramidal recess of the upper guide block.
Abstract:
The present invention is directed to a method for treating discolored natural diamond, especially Type IIa diamond and Type IaA/B diamond with nitrogen as predominantly B centers, for improving its color. The method includes preblocking and preshaping a discolored natural diamond to prevent its breakage in a high pressure/high temperature (HP/HT) press, placing said discolored natural diamond in a pressure transmitting medium which is consolidated into a pill. Next, the pill is placed into a HP/HT press at elevated pressure and elevated temperature within the graphite-stable or diamond-stable range of the carbon phase diagram for a time sufficient to improve the color of said diamond. Finally, the diamond is recovered from said press. Colorless and fancy colored diamonds can be made by this method.
Abstract:
PURPOSE:To generate ultrahigh pressure easily by forming a divided sphere comprising >=4 truncated pyramids having spherical bases which are movable freely toward central direction with each other, and providing a vertically bisectable vessel covering the whole body of the divided sphere. CONSTITUTION:A positioning pin 8 is inserted into each pin hole 8a bored in the recessed part of the hemisphere 6 with the tip end of the pin protruded from the pin hole. Positioning of the divided body 5 is executed by assembling the divided body 5 by fitting the side surface of the divided body 5 to the pin 8. By this process, each divided body is positioned, and adjacent divided bodies 5 are held with a small distance corresponding to the dia. of the pin 8 from each other. If the divided body is divided into six parts, 3-4 bodies are first assembled, then, a material to be compressed such as graphite is contained in a pressurizing chamber 1 formed in the central part, then residual divided bodies 5 are assembled thereafter to form a spherical body as a whole which is a dividable sphere 2.
Abstract:
Methods of forming noncrystalline diamond compacts include employing field assisted sintering techniques with high temperature and high pressure sintering techniques. For example, a particle mixture that includes diamond particles may be sintered by subjecting the particle mixture to a high temperature and high pressure sintering cycle, and pulsing direct electrical current through the particle mixture during at least a portion of the high temperature and high pressure sintering cycle. The polycrystal!ine diamond compacts may be used to form cutting elements for earth-boring tools. Sintering systems are configured to perform such sintering processes.