Synthesis Of Titanium Diboride Ultrafine Powder In Molten Salt

Titanium diboride has a lot of attractive properties like high melting point, highVickers hardness, excellent wear resistance, high electrical conductivity, as well asexceptional chemical resistance to acids and molten metals. So the potential applicationsin ceramics, functional materials, composites, refractories and aerial materials can beexpected. TiB2powders with uniform chemical composition and particle sizedistribution as well as high activity are essential to produce advanced materials. In thispaper, a new technology of powder preparation has been studied to solve the problemincluding reaction temperature was too high, synthesis process was difficult to control,and the particle size was too large. The powder was prepared in molten salt bymetallothermic reduction of oxides. The effect of the synthesis temperature, the ratio ofreaction materials, the holding time, the composition of molten salts, the types ofreduction agent on the structure and morphology of titanium boride powder wasinvestigated. The main results were as follows:Titanium boride nanopowder was synthesized in the range of800~1100for2~6hin molten salts(NaCl-KCl NaCl-CaCl2NaCl KCl) using titanium and boron trioxideas starting materials, and magnesium as reducing agent. When w(B2O3)/w(Mg) ratiowas3:1, the TiB2showed cubic and hexagonal shape with the particle size of40~200nm after heating at1000for4h in NaCl-KCl molten salt, and the specific surface areawas52.714m2/g. TiB2-Al18B4O33composite powder was synthesized at1000for4husing aluminium as reducing agent.Using titanium dioxide and boron as starting materials, magnesium as reducingagent, TiB2nanopowder was synthesized in the range of800~1100for3~6h inmolten salts (NaCl-KCl NaCl-CaCl2NaCl-KCl-K2TiF6NaCl KCl). When Ti/B moleratio was1:2.4, the TiB2showed a spherical morphology with the particle size of5~30nm after heating at1000for3h in NaCl-KCl molten salt. When the holding timeincreased to6h, the morphology of TiB2changed into a cubic shape, the particle size increased to30~60nm, and the specific surface area was49.142m2/g. TiB2-Al2O3composite powder was synthesized at1000for6h using aluminium as reducingagent.Titanium boride nanopowder was synthesized in the range of950~1050for4hin molten salts(NaCl-KCl NaCl-CaCl2KCl) using titanium dioxide and boron trioxideas starting materials, and magnesium as reducing agent. When mole ratio of TiO2, B2O3and Mg was1:4:8.5, the TiB2showed cubic and hexagonal shape with the particle sizeof50nm after heating at1000for4h in NaCl-KCl molten salt. TiB2-Al18B4O33composite powder was synthesized at1000for4h using aluminium as reducingagent.