Abstract: The present invention discloses a method for densifying previously sintered parts constructed of powdered metals, ceramics or the like to nearly 100% theoretical density. The method of the present invention comprises heating the parts containing binder and hard phase above their liquid phase temperature and then applying a pressure in a predetermined range to the parts for a predetermined period of time and simultaneously maintaining the parts at or above their liquid phase temperature. This pressure range is set so that the pressure is below the pressure necessary to overcome the capillary force acting on the binder to keep the binder from entering the voids but above the pressure necessary to physically move or collapse the microstructure inwardly, thus filling the voids with a homogenous mixture of binder and hard phase. The method of the present invention achieves complete closure of even large voids and the elimination of substantially all porosity within the part.

Abstract: The present invention provides a method for controlling the carbon content of dewaxed carbide preforms in a carbon containing furnace. The method includes the steps of placing the preforms in a carbon containing furnace and then heating the furnace to a predetermined temperature range between 800 and 1100 degrees Centigrade. At that temperature, a mixture of methane and hydrogen is introduced into the furnace chamber such that the amount of methane is between 10 and 90 percent of the amount of methane present at equilibrium for the reaction C.sub.solid +2H.sub.2 .revreaction.CH.sub.4. The furnace chamber is maintained at its temperature for a first time period sufficient for the chemical reaction XC+2H2.revreaction.X+CH.sub.4 (where X is selected from the group of W, Ti, Ta, Hf and No) substantially reaches equilibrium but shorter than the a second time period in which the reaction C.sub.solid +2H2.revreaction.CH.sub.

Abstract: The present invention discloses a method for densifying previously sintered parts constructed of powdered metals, ceramics or the like to nearly 100% theoretical density. The method of the present invention comprises heating the parts containing binder and hard phase above their liquid phase temperature and then applying a pressure in a predetermined range to the parts for a predetermined period of time and simultaneously maintaining the parts at or above their liquid phase temperature. This pressure range is set so that the pressure is below the pressure necessary to overcome the capillary force acting on the binder to keep the binder from entering the voids but above the pressure necessary to physically move or collapse themicrostructure inwardly, thus filling the voids with a homogeneous mixture of binder and hard phase. The method of the present invention achieves complete closure of even large voids and the elimination of substantially all porosity within the part.

Abstract: A delivery system is provided for use in conjunction with the metalurgical furnace of the type having an elongated furnace chamber with an access door at one end for delivering a coffin containing parts into the interior of the furnace chamber. The delivery system comprises a plurality of rollers which are secured to the bottom of the furnace chamber so that axes of the rollers extend transversely with respect to the axis of the furnace chamber. In use, the rollers frictionally engage the bottom of the coffin and guide the coffin into the furnace chamber. Preferably, the coffin includes upwardly extending channels on its bottom, and which the rollers are positioned.

Abstract: A delivery system is provided for use in conjunction with the metallurgical furnace of the type having an elongated furnace chamber with an access door at one end for delivering a coffin containing parts into the interior of the furnace chamber. The delivery system comprises a plurality of rollers which are secured to the bottom of the furnace chamber so that axes of the rollers extend transversely with respect to the axis of the furnace chamber. In use, the rollers frictionally engage the bottom of the coffin and guide the coffin into the furnace chamber. Preferably, the coffin includes upwardly extending channels on its bottom, and which the rollers are positioned.

Abstract: The present invention discloses a method for densifying previously sintered parts constructed of powdered metals, ceramics or the like to nearly 100% theoretical density. The method of the present invention comprises heating the parts above their liquid phase temperature and then applying a pressure in the range of 50-2,000 psi to the parts for a predetermined period of time and simultaneously maintaining the parts at or above their liquid phase temperature. The method of the present invention achieves complete closure of even large voids and the elimination of substantially all porosity within the part.

Abstract: A metallurgical furnace is disclosed which carries out the several steps involved in the liquid phase sintering of preforms of powdered metals, ceramics, and/or combinations of these materials. The metallurgical furnace comprises a pressure vessel defining an interior pressure chamber and a main furnace which is contained within the pressure chamber and spaced inwardly from the walls of the pressure vessel. The main furnace comprises a bottom wall, side walls, top wall and end walls which together form a substantially closed furnace chamber. Each of these furnace walls comprises at least one layer of insulation and, in addition, the top, sides, and end walls further include a vapor barrier which minimizes convection within the furnace chamber. The metallurgical furnace according to the present invention is capable of performing the presinter, sinter and hot isostatic pressing of preforms within the furnace chamber.

Abstract: A coated cemented carbide article comprises a cemented carbide substrate, the surface regions thereof having diffused therein an element such as boron, silicon or aluminum. The article further comprises a coating disposed on the diffused substrate, the coating being a boride such as titanium boride, hafnium boride, zirconium boride or tantalum boride. In another embodiment the coated cemented article further includes an interlayer sandwiched between the diffused substrate and the boride coating, the interlayer being one or more layers formed from the carbides, nitrides or carbonitrides of elements from groups IVb and Vb of the Periodic Table of Elements, and combinations thereof.