High pressure and free sintering of cermet composites with nanometric TiC participation

Paweł Figiel, Lucyna Jaworska, Piotr Putyra, Piotr Klimczyk, Krzysztof Bryła 1-4 Instytut Zaawansowanych Technologii Wytwarzania, ul. Wrocławska 37a, 30-011 Kraków, Poland 2, 5 Akademia Pedagogiczna, Instytut Techniki, ul. Podchorążych 2, 30-084 Kraków, Poland

Quarterly No. 2, 2008 pages 130-135

DOI:

keywords: cermet composites, materials for cutting edges, nanometric particles, high pressure sintering

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abstract Cermets are characterized very good plasticity and high hardness. Due to their low chemical affinity to Fe and the resistance for high temperatures oxidation, cermets have better cutting properties than carbides. Although having many good parameters with respect to their properties, cermets do have several properties which are not as good as those of cemented carbides, such as: lower fracture toughness, lower resistance for plastic deformation, higher thermal expansion. The aim of studies was to determine strength properties for materials obtaining using various methods of sintering. Materials with 70 vol.% of TiC and 30 vol.% of (Ni,Mo), and 56 vol.% of TiC and 44 vol.% of (Ni,Mo) were obtained using free sintering at vacuum and using HP HT apparatus. The various size of the TiC particles 2 µm, 130 nm and 2030 nm were used. The influence of the size of TiC particles on microstructure, density, hardness, Young modulus and fracture toughness was investigated. Furthermore, fracture toughness was calculated from the length of cracks which develop during a Vickers indentation test. In our case, fracture toughness KIc was calculated from Niihara’s equation. This paper also presents structure analysis of cermet composites with different size of TiC particles. This microstructure investigation was carried out with application of scanning microscope JEOL JA-50A. Phase analysis of cermet composites were carried out using X-Ray diffractometer DRON 3. For free sintering samples, with micrometric size of grains, the hardness of material is the highest. The ring structure of material and complex carbide (Ti,Mo)CX formation was confirm. During free sintering, intermetalics compounds are formed. X-Ray diffraction confirmed various composition of (Ti,Mo)C cermets, obtained using the free sintering method compare to cermets from the HP HT method. During the short time of the pressure sintering (60 s) process in the materials pure initial Mo and Ni are presence. In the high pressure sintered material with 130 nm TiC participation, there is small amount of TiC in the centre of carbide grains.