The invention relates to the rare metal smelting field, and particularly, the present invention relates to a tantalum powder for preparing capacitors and a process for preparing the tantalum powder, and to a sintered anode prepared from the tantalum powder. As to the tantalum powder as provided by the invention, its primary tantalum powder has a BET of from 3.0 to 4.5 m.sup.2/g. After the secondary agglomeration, the tantalum powder has a large particle size. The tantalum powder has an average Fisher sub-sieve size (FSSS) of 1.2 to 3.0 μm wherein as measured with a standard sieve mesh, more than 75% of tantalum powder has a +325-mesh, and a particle size distribution D50 of more than 60 μm, that is, the secondary particle size is high. A resultant capacitor anode prepared by sintering the tantalum powder of the invention at 1200° C. for 20 minutes and then being energized at the voltage of 20 V has the specific capacitance of from 140,000 to 180,000 μFV/g and the residual current of less than 1.0 nA/μFV. Meantime, the invention provides an economical process for making the tantalum powder.

A method of forming cemented tungsten tetraboride, by combining tungsten and boron in a molar ratio of from about 1:6 to about 1:12, respectively, and firing the combined tungsten and boron in a hexagonal boron nitride crucible at a temperature of from about 1600 C to about 2000 C, to form tungsten tetraboride, milling the tungsten tetraboride to a powder, adding a metal binder to the tungsten tetraboride powder to produce a metal-tungsten tetraboride mixture, compressing the metal-tungsten tetraboride mixture, and sintering the compressed metal-tungsten tetraboride mixture to form cemented tungsten tetraboride.

A method of forming cemented tungsten tetraboride, by combining tungsten and boron in a molar ratio of from about 1:6 to about 1:12, respectively, and firing the combined tungsten and boron in a hexagonal boron nitride crucible at a temperature of from about 1600 C to about 2000 C, to form tungsten tetraboride, milling the tungsten tetraboride to a powder, adding a metal binder to the tungsten tetraboride powder to produce a metal-tungsten tetraboride mixture, compressing the metal-tungsten tetraboride mixture, and sintering the compressed metal-tungsten tetraboride mixture to form cemented tungsten tetraboride.

A method for preparing a Nd—Fe—B-based sintered magnet. The method includes: 1) providing a master alloy and an auxiliary alloy, the master alloy being a Nd—Fe—B alloy ingot or cast strip, the auxiliary alloy being a heavy rare earth alloy; 2) breaking up the master alloy using a hydrogen decrepitation process to yield a crude powder, conducting hydrogen absorption treatment on the auxiliary alloy and breaking up the hydrogenated auxiliary alloy to yield hydride particles; 3) uniformly mixing and stirring the crude powder of the master alloy and the hydride particles of the auxiliary alloy to yield a mixture; 4) milling the mixture obtained in step 3) to yield powders; 5) uniformly stirring the powders obtained in step 4) and conducting orientation forming treatment on the powders, to yield a raw body of a Nd—Fe—B based magnet; and 6) sintering the raw body of the Nd—Fe—B based magnet.

A method for preparing a Nd—Fe—B-based sintered magnet. The method includes: 1) providing a master alloy and an auxiliary alloy, the master alloy being a Nd—Fe—B alloy ingot or cast strip, the auxiliary alloy being a heavy rare earth alloy; 2) breaking up the master alloy using a hydrogen decrepitation process to yield a crude powder, conducting hydrogen absorption treatment on the auxiliary alloy and breaking up the hydrogenated auxiliary alloy to yield hydride particles; 3) uniformly mixing and stirring the crude powder of the master alloy and the hydride particles of the auxiliary alloy to yield a mixture; 4) milling the mixture obtained in step 3) to yield powders; 5) uniformly stirring the powders obtained in step 4) and conducting orientation forming treatment on the powders, to yield a raw body of a Nd—Fe—B based magnet; and 6) sintering the raw body of the Nd—Fe—B based magnet.

A frame integrated vacuum hot press comprises a frame chamber including a vacuum space having an opened side; a door installed to the frame chamber to open or close the opened side of the vacuum space; a heating chamber including a heating space and a heater heating an object to be formed which is loaded in the heating space; and a cylinder which is connected to the frame chamber to apply pressure to the object to be formed which is loaded in the heating space of the heating chamber.

A frame integrated vacuum hot press comprises a frame chamber including a vacuum space having an opened side; a door installed to the frame chamber to open or close the opened side of the vacuum space; a heating chamber including a heating space and a heater heating an object to be formed which is loaded in the heating space; and a cylinder which is connected to the frame chamber to apply pressure to the object to be formed which is loaded in the heating space of the heating chamber.

A composite soft magnetic material having low magnetostriction and high magnetic flux density contains: pure iron-based composite soft magnetic powder particles that are subjected to an insulating treatment by a Mg-containing insulating film or a phosphate film; and Fe—Si alloy powder particles including 11%-16% by mass of Si. A ratio of an amount of the Fe—Si alloy powder particles to a total amount is in a range of 10%-60% by mass. A method for producing the composite soft magnetic material comprises the steps of: mixing a pure iron-based composite soft magnetic powder, and the Fe—Si alloy powder in such a manner that a ratio of the Fe—Si alloy powder to a total amount is in a range of 10%-60%; subjecting a resultant mixture to compression molding; and subjecting a resultant molded body to a baking treatment in a non-oxidizing atmosphere.

A composite soft magnetic material having low magnetostriction and high magnetic flux density contains: pure iron-based composite soft magnetic powder particles that are subjected to an insulating treatment by a Mg-containing insulating film or a phosphate film; and Fe—Si alloy powder particles including 11%-16% by mass of Si. A ratio of an amount of the Fe—Si alloy powder particles to a total amount is in a range of 10%-60% by mass. A method for producing the composite soft magnetic material comprises the steps of: mixing a pure iron-based composite soft magnetic powder, and the Fe—Si alloy powder in such a manner that a ratio of the Fe—Si alloy powder to a total amount is in a range of 10%-60%; subjecting a resultant mixture to compression molding; and subjecting a resultant molded body to a baking treatment in a non-oxidizing atmosphere.

[Object] There is provided a porous sintered body has a uniform porosity, a high level of freedom in body formation which allows formation into varieties shapes and various levels of porosity, and a very large surface area. [Solution] The porous sintered body includes: hollow cores which follow a vanished shape of an interlaced or otherwise structured fibriform vanisher material; sintered walls 226 which extend longitudinally of the cores and obtained by sintering a first sintering powder held around the cores; and voids formed between the sintered walls. The cores and the voids communicate with each other via absent regions formed in the sintered walls. The sintered walls have surfaces formed with a sintered microparticulate layer 232 made from a material containing a second sintering powder which has a smaller diameter than the first sintering powder, and has predetermined pores 231.