Abstract
Titanium diboride (TiB2) is a hard, refractory material, attractive for a number of applications, including wear-resistant machine parts and tools, but it is difficult to densify. The spark plasma sintering (SPS) method allows producing TiB2-based composites of high density with different sintering aids, among them titanium silicides. In this paper, Ti5Si3 is used as a sintering aid for the sintering of TiB2/10 wt % Ti5Si3 and TiB2/20 wt % Ti5Si3 composites at 1600 °C and 1700 °C for 10 min. The phase composition of the initial powders and produced composites was analyzed by the X-ray diffraction method using CuKα radiation. The microstructure was examined using scanning electron microscopy, accompanied by energy-dispersive spectroscopy (EDS). The hardness was determined using a diamond indenter of Vickers geometry loaded at 9.81 N. Friction–wear properties were tested in the dry sliding test in a ball-on-disc configuration, using WC as a counterpart material. The major phases present in the TiB2/Ti5Si3 composites were TiB2 and Ti5Si3. Traces of TiC were also identified. The hardness of the TiB2/Ti5Si3 composites was in the range of 1860–2056 HV1 and decreased with Ti5Si3 content, as well as the specific wear rate Wv. The coefficient of friction for the composites was in the range of 0.5–0.54, almost the same as for TiB2 sinters. The main mechanism of wear was abrasive.
Highlights
IntroductionThe most extensively studied phase in the Ti-B system is titanium diboride, as it is the hardest and most thermodynamically stable
The most extensively studied phase in the Ti-B system is titanium diboride, as it is the hardest and most thermodynamically stable. It is characterized by an extremely high melting point (3225 ◦ C), high hardness (35–40 GPa) and Young’s modulus (450 GPa), which are associated with relatively high thermal (60–120 W/mK) and electrical conductivities
The aim of this study is to densify TiB2 /Ti5 Si3 micropowders by the spark plasma sintering (SPS) method and to study the influence of Ti5 Si3 addition on the microstructure, hardness and friction–wear properties of the produced composites
Summary
The most extensively studied phase in the Ti-B system is titanium diboride, as it is the hardest and most thermodynamically stable It is characterized by an extremely high melting point (3225 ◦ C), high hardness (35–40 GPa) and Young’s modulus (450 GPa), which are associated with relatively high thermal (60–120 W/mK) and electrical conductivities (~105 S/cm) [1]. Due to this unique set of properties, titanium diboride is an attractive material for a number of applications, including cutting tools, wear-resistant parts and coatings, ballistic armor, cathodes in Hall–Heroult cells for aluminum smelting, crucibles for handling molten metals and metal evaporation boats [1,2]. It was demonstrated that by the SPS method, using simultaneously pulsed direct current and uniaxial pressure, TiB2 sinters of 96% theoretical density could be produced within 10 min at a temperature range of
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