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The effect of porosity on thermal properties of TiB2-based Cu cermets obtained by ball milling and containerless HIP DOI:10.15199/28.2016.3.3

  The effect of porosity on microstructure and thermal properties of titanium diboride (TiB2) based cermets with Cu binder was investigated. It has been demonstrated a good wettability of the TiB2-Cu interfaces which allows for heat flow through it easily but formed microporosity (25÷32 %) and related structural defects in the sintered cermets affects the thermal conductivity. The specific heat changes exponentially with temperature and amounts to 0.37 J∙g-1K-1 at 298 K for the TiB2-Cu (20 vol. %) cermet with the lowest porosity. The X-ray diffraction (XRD) analysis confirmed that TiB2-Cu is the stable system and there was no reaction between TiB2 and Cu. The dependence of microstructure and composition on thermal properties of sintered the TiB2-Cu cermet alloys was discussed. Key words: titanium diboride, TiB2-Cu cermets, ceramic matrix composites (CMCs), hot isostatic pressing, HIP, thermal properties. Inżynieria Materiałowa 3 (211) (2016) 109÷114 DOI 10.15199/28.2016.3.3 1. INTRODUCTION Titanium diboride (TiB2) is one of a few refractory metal borides with an attractive combination of properties such as high melting point (3225°C), ultra-high hardness (25 GPa), high strength to density ratio, good thermal and electrical conductivity (96 W∙m-1K-1 and 22∙106 Wcm, respectively) and wear resistance [1, 2]. TiB2 can be used to produce dense constructive sintered materials for high-temperature structural applications as well as for control rod elements with a high-thermal neutron absorption in nuclear reactors. However, it is well known, that wide applications of TiB2 ceramic are limited due to poor sintering ability, which requires extremely high temperature [3, 4]. The interesting approach for obtaining the TiB2 based cermets is the sintering method by hot isostatic pressing (HIP). In this way by intensive mass transfer the sintering process is carried out in shorter time and at lower temperature. The lower temperatu[...]

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