Diamond the ceramics bonding phase composites microstructure modification reinforced to the tool body brazing
Lucyna Jaworska*, Marcin Rozmus*, Agnieszka Twardowska**, Bogna Królicka*** *Instytut Zaawansowanych Technologii Wytwarzania, ul. Wrocławska 37a, 30-011 Kraków **Akademia Pedagogiczna, Instytut Techniki, ul. Podchorążych 2, 30-084 Kraków ***Instytut Zaawansowanych Technologii Wytwarzania, ul. Wrocławska 37a, 30-011 Kraków
Quarterly No. 3, 2006 pages 3-7
DOI:
keywords: diamond-Ti3SiC2 composite, materials for cutting edges, functionally graded materials
abstract One of the most popular tools materials is diamond. Currently there are three groups of diamond based cutting tool materials available namely polycrystalline diamond compacts PCD, CVD diamond and single crystal natural and synthetic diamond. The most significance for machining have PCD materials. The PCD compacts are a round disks comprising a thin layer of sintered polycrystalline diamond bonded to a cemented tungsten carbide substrate (Fig. 1). Commercially available PCD are usually made by high pressure sintering diamond powders with the cobalt bonding phase. The existence of cobalt promotes the graphitisation process of diamond. The differential thermal expansion of PCD layer and tungsten carbide substrate may result in residual stresses and next, delamination of material. Modification properties of these materials are possible using suitable kind of the bonding phase material, for example the ceramics Ti3SiC2 material, which is exhibiting pseudoplastics behaviour. The 30 wt.% Ti3SiC2 addition to the diamond composite is resulted high fracture toughness, KIC is 8 MPa ⋅ m1/2, compressive strength is three times more than for compacts with the cobalt bonding phase (Table 1). The thermal resistance of these materials were increased also. The decomposition of Ti3SiC2 takes place during the high pressure sintering process (Fig. 2). Observations of microstructure of prepared composites showed that mixing diamond and Ti3SiC2 powder produces composites of very low porosity (Fig. 3) and indicated that the bonding material has a multiphase composition (Fig. 4). Using the Ti3SiC2 bonding phase in the gradient composition material allows for the direct brazing of the edge to the tools body without intermediate sintered carbides layer. These functional graded materials will provide the cutting tools hard, wear resistant surface and good brazing substrate. The grading material was compacted using the centrifugal method.