Roman Pampuch

New ceramics based on Ti3SiC2

Abstract Dense polycrystalline Ti 3 SiC 2 -based materials in the form of large shapes were obtained by ceramic processing starting with SHS-derived Ti 3 SiC 2 -based powders. Their high Youngs and shear moduli and chemical resistance classified them as a covalent ceramic material. However, their relatively low hardness and ratio of high Youngs modulus to hardness are close to those of ductile metals.

Some fundamental versus practical aspects of self propagating high-temperature synthesis

Earlier papers about self-propagating high-temperature synthesis (in short SHS) usually do not convey to non-specialists how to translate the basic facts and fundamental concepts of SHS into the realization of this method in terms, for instance, of particle size of the reactants, of thermal conductivity and mode of heating up of beds of articulate reactants; these differ substantially from the ones used for synthesis of solid compounds by conventional furnace methods. Moreover, in contrast to the energy saving features of SHS, less known is the fact that the specific mechanism of SHS reactions and the resulting nature of the products enable a simplification of processing of primary SHS products to materials. Knowledge of implications of the theory for the practice of SHS is important because the method has evolved into a technique which is being applied to the production of a wide variety of ceramic, intermetallic and composite materials. In order to illustrate these implications a number of examples, based mainly on investigations into SHS in solid-solid reactive systems, is discussed in the present paper.

Solid combustion synthesis of refractory carbides: (A review)

Abstract The specific mechanisms of heterogeneous reactions which are likely to occur during solid combustion synthesis in the TiSiC system are reviewed. Also discussed are the properties of some products of solid combustion as compared with these from other advanced methods of synthesis and the competitiveness of this process with other advanced methods of production of ceramic carbide powders.

Supersaturated solid solutions of boron in SiC by SHS

Abstract Sintering of dense silicon carbide products requires specially prepared starting powders with a small grain size, high purity, and appropriate contents of sintering activators. A method for the preparation of such powders with boron dopant by self-propagating high-temperature synthesis (SHS) is described. Supersaturated solid solutions of boron in βSiC with a boron content of up to 20 wt% were synthesized. Such powders were sintered to high densities by pressureless sintering at relatively low temperatures in a range of 2050–2150°C.

Microstructure-property relationship in B4C-βSiC materials

Abstract The microstructure-property relationships have been studied in B 4 C-βSiC materials for boron contents from 0 to 30 wt.% (corresponding to a range from 0 to about 45 vol.% of B 4 C). The materials were produced by sintering or hot-pressing of composite BSiC powders synthesized by solid combustion. In order to characterise the microstructure quantitatively, observations of polished sections of the materials, etched by potassium salts, were made by using the scanning electron microscopy. After binarisation, the data were eventually subjected to image processing. For both coexisting phases (βSiC and B 4 C) the distribution and mean values of the following microstructural parameters were determined: grain area, grain aspect ratio and grain dimensions. The electrical resistivity and bending strength were also determined for the materials characterised microstructurally.

Ceramic Tool Materials for High Speed Cutting Process

Frictional and mechanical properties of hot-pressed Al2O3 and Si3N4 - matrix composites containing up to 5 vol. % hexagonal BN as a solid lubricant. A very low coefficient of friction which is necessary for high-speed cutting has been observed. Fracture toughness remained constant with increase of h-BN content while flexural strength changes with the hBN content have been found to depend upon the material homogeneity. The work has been supported by EU Funds in Poland under contract UDA-POIG.01.03-12-024/08-00.and has been realized in the frame of scientific-industrial consortium.