| 摘要 |
1,188,088. Powder metallurgy; coating with W-Re alloys. ALLIED CHEMICAL CORP. April 24, 1968 [April 25, 1967], No.19475/68. Headings C7D and C7F. A tungsten 0‹5-25% Re alloy is deposited on refractory seed particles (e. g. of refractory metal with a melting point above 1500‹ C. such as W, Ta, Nb, Mo, Re or alloys thereof, oxides of Mg, Th, Al, Zr, Be, Y, U, Ti, Cr, have earth metals or mixtures thereof or tungsten or zirconium carbides, borides or nitrides) by reduction of a gaseous mixture of W and Re hexafluorides by a stoichiometric excess of hydrogen in a fluidized bed of the seed particles of at least 205‹ C. The seed particles may have an average size of over 5 Á and preferably over 50 Á, the product size being 10-10, 000Á (e. g. 200-600Á). The particles may be consolidated by placing them in a thin walled container, packing them, by vibration to give a bulk density of at least 65% theoretical, evacuating the container and heating it with a sufficient gas pressure for long enough to form a unitary mass (e. g. a pressure of 350-1, 400 kg/cm<SP>2</SP> of Ar or He, at 1, 090-1, 930‹ C. for several minutes to several hours). |
