Ceramtec Ag

Ceramtec Ag, Innovative Ceramic Engineering

Dirk Rogowski

Ilka Lenke

Dieter Theil

Hans-Georg Pfaff

Alwin Nagel

Both ceramic and intermetallic materials as a rule have a very small elongation at break of distinctly less than 0.3% and therefore a break behaviour with low damage tolerance. In order to increase the damage tolerance, it is important to increase the elongation at break to at least 0.3% or more. This can be achieved by introducing, for example, fibres consisting of carbon or ceramic or metal fibres into the matrix. It is important in this respect for the distribution of the fibres in the matrix to be homogeneous and/or defined. It is of advantage and therefore as a rule desirable for the fibres for reinforcing a material or component to be oriented in a defined direction which is adapted to the main stress. Therefore, according to the invention, a fibre-ceramic composite is proposed which consists of a ceramic matrix with a pore proportion of 0% to 75% and a fibre proportion of 5% by volume to 30% by volume, wherein the distribution of the fibres in the matrix is homogeneous and/or defined, and their quantity and orientation are optimized in relation to the material load.

Porous fiber-ceramic composite

A composite of a metal matrix with one or more incorporated secondary phases is referred to as a metal matrix composite (MMC). Secondary phase refers to all the particles or fibers which have a different composition than the metal matrix, and which are incorporated therein. As incorporation phases, elements and compounds are possible which, as a result of their material characteristics, are suited for improving individual properties of the metal matrix. Besides an improvement in individual properties of the pure metal matrix as a result of the incorporated secondary phase, certain properties of the metal are also degraded, in particular by particles having a size of 1 to 50 &#x3bc;m. For example, the elongation at break decreases, the strength may decrease, or the tribology may become less favorable. The object of the invention is to improve the properties of the composites by an appropriate selection of the size and type of fibers and/or particles in the secondary phase, and/or the formation of a special pore structure in the preform.

Composites and method for manufacturing same

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.

Growing community of inventors

Ebersbach a.d. Fils, Germany

Dirk Rogowski