Abstract: The production of moulded bodies from hard-metal powders by pressing and simultaneous or subsequent heat treatment is known. The mixture of hard material powders and aluminium powders for producing dry-pressed moulded bodies is an example thereof. As a result of the risk of demixing and the loss of homogeneity, the upper limit, for example according to prior art, for the proportion of hard material particles added to the aluminium powder is approximately 20 vol. %. The aim of the invention is to increase the proportion of hard material particles it the mixture. To this end, the inventive method for producing metal ceramic composite materials is characterised by dry-pressing powders with base compositions of between 25 and 79 vol. % of at least one metallic phase, preferably aluminium and the alloys thereof, and between 75 and 21 vol. % of at least one non-metallic inorganic constitnent, as ceramic materials, preferably silicon carbides, aluminium oxides, titanium oxides, carbon and silicates.

Abstract: A cutting matrix has a top surface, a first cavity for tightening the cutting matrix in a cutting tool, and a cutting edge for cutting by stock removal. A second tightening cavity is arranged coaxially with respect to the first cavity. The first cavity is deeper than the second, and both are below the upper surface of the cutting matrix.

Abstract: A block of stacked green films provided with internal electrodes is laminated, at least one actuator is separated from the block, the actuator obtains its shape by means of a machining operation, is then sintered, and the sinter skin produced by the sintering is used as an insulating layer. The sinter skin is abraded at the points where the internal electrodes are connected to the external electrodes.

Abstract: The invention relates to a clamping claw having a securing leg and a clamping leg for securing an object in a first recess of a support, with the clamping claw in the installed state being secured on the support by way of its securing leg by means of a bolt and clamping the object in the recess by means of its clamping leg. To split the application of axial force applied to an object by a clamping claw in part into an application of force that acts transversely thereto, the clamping claw includes two portions, namely a clamping base and a clamping finger, the clamping base sits on the support in the installed state of the clamping claw, the clamping finger has a securing leg and a clamping leg, and the installed state the securing leg sits on the clamping base over an oblique plane formed as a sliding surface and clamps the object with its clamping leg.

Abstract: The characteristics of piezoceramic multilayer actuators based on lead-zirconate-titanate are determined to a great extent by the compatibility of PZT ceramics having a low sintering temperature with the AgPd internal metallisation during cofiring. It is important to take into consideration that Ag ions in PZT modifications have a high diffusivity at high temperatures (>800° C.) and in addition act as acceptor doping when integrated into the PZT system. The reduction of the fraction of the precious metal palladium, which prevents diffusion, is limited, as silver increasingly diffuses into the piezoceramic as the silver fraction in the internal electrodes increases. According to the invention, Ag+ ions are used to form valence-compensated compositions of the PZT system. A higher level of deformation is maintained, i.e. the acceptor-donor effect in the system is very similar to that of the PZT system modified conventionally without internal electrodes.

Abstract: Porous coatings on high-performance ceramics attempt to combine the mechanical and thermal characteristics, which fulfil stringent demands, of the substrate material with the advantageous properties of coating materials. The subsequent application of layers of this type to the pre-sintered substrate produces unsatisfactory results in several areas of use with regard to possible layer thickness, porosity and adhesion. According to the invention, a shaped body consisting of a sintered, inorganic material, whose surface comprises a porous layer is produced in such a way that the base body is first formed as a green body. A layer in the form of a suspension, also containing an inorganic material, is then applied to the surface or to one section of the surface of the base body. A predetermined fraction of a pore-forming substance is mixed with at least the material of said layer and the green body with its applied layer is subjected to the thermal treatments required for producing a monolithic sintered body.

Abstract: The invention relates to a method for the manufacture of piezoelectric multilayer actuator in which thin layers of a piezoceramic material, called “green leaves” on which at least one internal electrode is applied, are stacked to form a block such that the internal electrodes are guided in alternation to oppositely lying surfaces of the actuator, where they become bound together by an external electrode, the actuator compact being sintered and subjected to abrasive shaping, and then the base metallization is applied for the external electrode.

Abstract: This invention is about SiALON ceramics comprising an alpha SiAlON, a beta SiAlON and an intergranular amorphous and/or crystalline phase. Said alpha SiALON phase was prepared from a multi-cationic mixture including the element of calcium, at least one of yttrium and/or a rare earth element with atomic number greater than 62 and at least one of a rare earth element with atomic number equal or smaller than 62. The second phase, beta SiALON contains elements of Si, Al, O, N. The third phase, amorphous and/or crystalline intergranular phase contains in addition to elements of Si, AL, O, N, element of calcium, at least one of yttrium and/or a rare earth element with atomic number greater than 62 and at least one of a rare earth element with atomic number equal or smaller than 62. This material with its toughness, high fracture resistance and high temperature resistance is useful for cutting tool applications and components in machinery and engines.

Abstract: In piezoceramic multilayer actuators, the head region and the foot region consist of inactive, that is to say electrode-free, piezoceramic layers. Due to the arrangement of the metallic electrodes and the layers of the piezoceramic materials, the shrinkage of the piezoceramic material, in particular in the passive head region and foot region, is influenced during the sintering process and can cause the formation of cracks. Different expansion behavior of the active and of the passive region during operation also lead to stresses which favor crack formation, in particular at the boundary between both regions. According to the invention, it is therefore proposed that a transition region (11), whose shrinkage and expansion behavior lies between the shrinkage and expansion behavior of the active region (10) and the shrinkage and expansion behavior of an inactive region (8, 9) which are electrode free, adjoins the active region (10) up to the inactive head region (8) and up to the inactive foot region (9).

Abstract: The invention relates to a monolithic multilayer actuator comprising a sintered stack of thin films, made from piezo-ceramic with inlaid metallic inner electrodes which extend from the stack on alternate sides and are electrically wired in parallel with external electrodes (3, 4) and are provided with connector wires (5). According to the invention, the actuator may be supplied with nominal voltage over a long period of time, without a change in the properties thereof, whereby the multilayer actuator (1) is sealed within a metallic or ceramic housing (8, 11, 16), the connector wires (5) are integral parts of the housing base (11) and the housing (8, 11, 16) is filled with a water-absorbing medium (14) and a water-transporting, electrically-insulating medium (15).

Abstract: With actuators according to prior art, it is known that, in the inactive region, which is required for contact purposes, irregularities in expansion occur. These produce cracks in the piezoelectrically inactive electrode region, which may occur at regular intervals. As a result of the irregularities in expansion, the stresses accumulate in the passively expanded regions, up to a level at which they are relieved by crack formation. It is therefore proposed according to the invention that the contact surfaces (17), and therefore the inactive regions (15) assigned to them, of one or a predetermined number of electrodes of the same polarity (11; 30 to 37; 39, 40), arranged above one another in the same direction, are arranged offset to one another by a predetermined angle (22) of the size ?, opposite the contact surfaces (17), and therefore the inactive regions (15) assigned to them, of the preceding internal electrode or a predetermined number of preceding electrodes of the same alignment and the same polarity.

Abstract: The invention relates to cast parts which contain at least 87 wt. % silicon nitride and up to 13 wt. % of an additive combination comprised of Al2O3 and Y2O3. The initial composition of the mass formulation starts with Y2O3/Al2O3 ratios of less than 1.1, preferably with Y2O3 Al2O3 ratios of 0.2 to 1.09. 1% to 20% of the Y2O3 portion can thus be substituted by an additional element group of IVb of the periodic table or by the oxide thereof. The cast parts can comprise up to 1.0 wt. % HfO2 and/or ZrO2. Said cast parts preferably have a thickness >98% of the theoretic thickness. At room temperature, the bending strength of the inventive cast parts amounts to ≧1100 MPa and amounts to ≧850 MPa at 1000° C. The inventive cast parts correspond to the formula Si6-zAlzOzN8-z. The degree of substitution z thus amounts to 0.20 to 0.60, preferably from 0.22 to 0.54, especially from 0.3 to 0.35.

Abstract: A hip joint prosthesis has an external metal shell, an internal socket insert in which a ball head can rotate. The ball head is joined to a metal prosthesis shaft of the femoral shaft component and the movement of the prosthesis shaft is limited by abutting against the margin of the socket insert. A soft, biocompatible cushioning element is applied to the socket insert on the circumferential surface of the prosthesis shaft.

Abstract: Joint prostheses which have one joint partner configured as a socket and the other joint partner configured as a ball head generally consist of two components. The socket is comprised of a metallic outer cup in which an insertion cup made of ceramic material or of a biocompatible plastic is inserted. The shaft has a peg, the so-called cone, on which a ball head is placed. The press fit connection, especially so-called conical pressing, is used as a connection technique between the respective components. Stress can result in a relative movement between the components, thus leading to a wear-related loosening of the connection thereof. In order to solve this problem, the invention provides that, from the prosthetic components (2, 3), the component (3) made of ceramic or plastic fitted with a covering (6), said covering being made of a biocompatible metal or of a biocompatible metal alloy, on the pressing surface (7) thereof via which said component (3) is connected to the metal component (2).

Abstract: External electrodes on piezoceramic multilayer actuators, composed of a layer of a basic metallization applied to the ceramic material of the surface of a actuator, to which metallization there is joined by means of a joining layer a reinforcing layer to which a connecting wire is soldered, wherein the layer of basic metallization is structured by discontinuities or recesses.

Abstract: During operation, large tensile stresses act on the insulating region under the base metallization with external electrodes on piezoceramic multilayer actuators. Since this insulating region forms a homogeneous unit together with the base metallization and the interconnecting layer, this fails when the tensile strength of the weakest element is exceeded and cracks develop. The cracks running unchecked through the insulating region are very critical, since they reduce the insulation distance and seriously increase the probability of actuator failure due to flashovers. According to the invention it is therefore proposed that, in the inactive region (14), the surface (10) of the multilayer actuator (1) has a pattern (18) that is produced by erosions (19) interrupting the surface (10), and that the base metallization (11) is deposited exclusively on the surface (10) left by the pattern (18).

Abstract: Joint prostheses, in which one joint partner is formed as a socket and the other joint partner is formed as a spherical head which is rotatably mounted in the socket, are known in particular as shoulder-joint and hip-joint prostheses. The force-fit connection, in particular conical jamming, is also used here as the connecting technique between metallic or ceramic spherical heads and the cone. A coupling element (6) is inserted between the cone (5) and the spherical head (3) of the force-fit connection (1). The elasticity and damping properties of the coupling element (6) can be predetermined by its porosity and the structure of its surface.

Abstract: A protective cap for prosthetic joints having one element in the form of a ball head, especially in the case of hip end-prosthetic joints, protects the ball head when it is positioned and fixed on the cone of the shank by the surgeon by hand. A crown is arranged on the pole of the protective cap. The crown is in the form of a plate for, the shape of the plate and its extent relative to the protective cap being such that it is possible to grip behind the plate on the side that faces the protective cap.

Abstract: The invention relates to cast parts which contain at least 87 wt. % silicon nitride and up to 13 wt. % of an additive combination comprised of Al2O3 and Y2O3. The initial composition of the mass formulation starts with Y2O3/Al2O3 ratios of less than 1.1, preferably with Y2O3 Al2O3 ratios of 0.2 to 1.09. 1% to 20% of the Y2O3 portion can thus be substituted by an additional element of the group IVb of the periodic table or by the oxide thereof. The cast parts can comprise up to 1.0 wt. % HfO2 and/or ZrO2. Said cast parts preferably have a thickness >98% of the theoretic thickness. At room temperature, the bending strength of the inventive cast parts amounts to ≧1100 MPa and amounts to ≧850 MPa at 1000° C. The inventive cast parts correspond to the formula Si6−zAlzOzN8−z. The degree of substitution z thus amounts to 0.20 to 0.60, preferably from 0.22 to 0.54, especially from 0.3 to 0.35.

Abstract: A method tests a ceramic socket insert of a hip joint endoprosthesis in which, in use, a spherical head articulates against a functional inner surface of a ceramic socket insert which is anchored in a pelvic bone by means of a socket housing. The method includes providing the ceramic socket insert in a holding arrangement, applying a predetermined pressing force to a predetermined sub-area of the functional inner surface of the ceramic socket insert, and applying a supporting force to a sub-area of an outer surface of the ceramic socket insert to counteract the pressing force. The predetermined sub-area of the functional inner surface symmetrically surrounds a pole of the inner surface of a ceramic socket insert. The predetermined force is such that stresses generated in the ceramic socket insert are higher than stresses generated in the case of a physiological load.