Abstract: A joint prosthesis comprises a first component having a bearing surface and a second component having a bearing surface arranged to articulate with the bearing surface of the first component, said bearing surfaces of the first and the second component thus forming a bearing couple. The bearing surfaces consist of a silicon carbide whisker reinforced alumina. Thus, a bearing couple with low wear, low friction and high hardness is provided.

Abstract: An improved cutting tool insert and a method for the preparation of such cutting tool insert, having a sintered alumina and silicon carbide whisker composite material body, comprising the steps of milling and mixing the powdered starting materials of said composite material and forming said material into a preformed workpiece, heating up said workpiece at a heating rate of from about 20 to about 60° C. per minute to a sintering temperature of between from about 1600 to about 2300° C., and holding at said sintering temperature for a holding time of from about 5 to about 60 minutes at a pressure of between from about 20 to about 100 MPa.

Abstract: An improved cutting tool insert and a method for the preparation of such cutting tool insert, having a sintered alumina and silicon carbide whisker composite material body, comprising the steps of milling and mixing the powdered starting materials of said composite material and forming said material into a preformed workpiece, heating up said workpiece at a heating rate of from about 20 to about 60° C. per minute to a sintering temperature of between from about 1600 to about 2300° C., and holding at said sintering temperature for a holding time of from about 5 to about 60 minutes at a pressure of between from about 20 to about 100 MPa.

Abstract: An improved cutting tool insert and a method for the preparation of such cutting tool insert, having a sintered alumina and silicon carbide whisker composite material body, comprising the steps of milling and mixing the powdered starting materials of said composite material and forming said material into a preformed workpiece, heating up said workpiece at a heating rate of from about 20 to about 60° C. per minute to a sintering temperature of between from about 1600 to about 2300° C., and holding at said sintering temperature for a holding time of from about 5 to about 60 minutes at a pressure of between from about 20 to about 100 MPa.

Abstract: An improved cutting tool insert and a method for the preparation of such cutting tool insert, having a sintered alumina and silicon carbide whisker composite material body, comprising the steps of milling and mixing the powdered starting materials of said composite material and forming said material into a preformed workpiece, heating up said workpiece at a heating rate of from about 20 to about 60° C. per minute to a sintering temperature of between from about 1600 to about 2300° C., and holding at said sintering temperature for a holding time of from about 5 to about 60 minutes at a pressure of between from about 20 to about 100 MPa.

Abstract: A method of making a whisker-reinforced ceramic body by hot pressing a preform to a disc, cutting the disc into blanks and grinding the blanks to bodies of desired shape and dimension is disclosed. The preform is prepared by dispersing 10-60% by volume of a ceramic powder mixture containing conventional sintering aids and/or grain growth inhibitors in water or an organic solvent adding 1-15 wt-% starch to the dispersion; pouring the dispersion into a mold with desired shape; heating the suspension to 50°-100° C. for 2-4 hours while covering the mold to avoid water evaporation to form a preform; removing the preform from the mold; and presintering the preform in air for 10 h at a maximum temperature of about 600° C.

Abstract: A sintered ceramic material for high speed machining of heat resistant alloys is provided comprising SiAlON grains and 0.2-20 v/o intergranular phase. At least 80 v/o of said SiAlON phase is beta SiAlON having a z-value greater than 1.0, but less than 1.5. The ceramic material has a Vickers Hardness HV1 of more than 1530 and it is produced by gas pressure sintering.

Abstract: A sintered ceramic material for high speed machining of heat resistant alloys is provided comprising SiAION grains and 0.2-20 v/o intergranular phase. At least 80 v/o of said SiAION phase is beta SiAION having a z-value greater than 1.0, but less than 1.5. The ceramic material has a Vickers Hardness HV1 of more than 1530 and it is produced by gas pressure sintering.

Abstract: Oxide-based ceramic cutting inserts for chipforming machining of steel, comprising a ceramic oxide-based matrix of alumina and less than 10% by volume zirconia and 5-40% by volume of homogeneously dispersed whiskers based upon (Ta.sub.x Hf.sub.y Ti.sub.1-x-y)C.sub.1-z N.sub.z where 0<x<0.75 and 0<y<0.75, x+y>0.25 and 0.ltoreq.z<1.

Abstract: There is disclosed a method of producing whiskers in large volumes and at low cost to be used as reinforcing material. The whiskers are solid solutions between two or more transition metal carbides, nitrides and carbonitrides, (Me.sub.1-X-Y.sub.Me'.sub.X+Y)C.sub.1-Z N.sub.Z, having preferably submicron diameters, where Me' is one or more transition metals other than Me. The whiskers are suitable for use as a reinforcement material in a wide range of materials, including metals, intermetallics, plastics, ceramics and metallic bonded hard material. Transition metal oxides, hydroxides or alkali compounds thereof are mixed with carbon powder. The carbon source is added in an amount to satisfy the stoichiometric requirements of the carbide or nitride. A halogenide salt is used as a volatilization agent for the transition metals and a catalyst such as Ni or Co that is able to dissolve transition metals plus C and/or N. The reactant powders are blended so as to intimately mix them.

Abstract: There is now provided an oxide based ceramic cutting insert for chipforming machining of heat resistant alloys comprising a ceramic oxide based matrix and 5-50% by volume of homogeneously dispersed whiskers of silicon carbide. The whiskers have an average length of 4-7 .mu.m, with substantially all of the whiskers having a length less than 10 .mu.m.

Abstract: There is now provided an oxide-based, preferably aluminum oxide based, matrix with 5-50, preferably 10-40% by volume of homogeneously dispersed whiskers based upon nitrides, carbides and/or borides of metals from group IVB (Ti,Zr,Hf) and/or VB (V,Nb,Ta) of the periodic system or solid solutions thereof and 1-20, preferably 3-8% by volume of particulate additions with a size <500 nm, preferably <200 nm, based upon carbides, nitrides and/or borides of metals from group IVB (Ti,Zr,Hf) and/or VB (V,Nb,Ta) of the periodic system or solid solutions thereof. The nanosize particulate additions are predominantly present inside the matrix grains and not in the grain boundaries.

Abstract: There is now provided a ceramic cutting tool material comprising a ceramic, preferably aluminum oxide based, matrix with 5-50%, preferably 10-40%, by volume of homogeneously dispersed SiC-whiskers and 1-20%, preferably 3-8%, by volume of particulate additions with a size <500 nm, preferably <200 nm, based upon carbides and/or nitrides and/or borides of metals from group VB (V,Nb,Ta) in the periodic system or solid solutions thereof. The nanosize particulate additions are predominantly present inside the matrix grains and not in the grain boundaries.

Abstract: The present invention discloses a ceramic cutting tool insert for chip-cutting machining. It comprises a body of generally polygonal or round shape having an upper face, an opposite face and at least one clearance face intersecting upper and lower faces to define cutting edges. The ceramic material is alumina based and comprises at least 10-40 volume % single crystal whiskers and/or platelets of carbides, nitrides and/or borides of Si, Ti, Zr, Hf, Ta and/or Nb or solid solutions thereof. The non-plane chip-forming surfaces of the insert comprise recessions and elevations that are formed in an uniaxial cold pressing operation.

Abstract: Ceramic materials intended for cutting and consisting of aluminum oxide with additives of hard carbides or nitrides, particularly titanium carbide, have up to now, because of their sintering inertia, in general been pressure sintered to obtain satisfactory properties. According to the present invention a ceramic alloy of excellent technological properties has been formed and comprises principally Al.sub.2 O.sub.3 and hard nitrides or carbonitrides, such as TiN or Ti(C,N) in which the alloy contains from 2 to 95 v/o of an Al--O--N-compound, such as nitrogen stabilized aluminum oxide with cubic or nearly cubic structure.