Zirconium silicide (zrsi), as a zirconium-silicon intermetallic compound, is a kind of high temperature ceramic material with high hardness, high melting point, high conductivity, high thermal conductivity and excellent thermal shock resistance. In view of these superior physical and chemical properties of zirconium-silicon intermetallic compounds, it is a kind of structural materials or new engineering materials that can be applied to high temperature corrosive media.
At present, The method of preparation of zirconium silicide is mainly with silicon thermal reduction process (powdermetall. Met. C, 1968,7,178.), mechanical alloying method (ceram. Int., 2015,41,5362.), self-propagating high-temperature synthesis (j.alloy.com pd., 1999288, 23 (8), reaction sintering, int. J j.a PPL. Ceram. Tec., 2006,3,23.) and arc smelting method (metall. Mater. Trans. A, 1995,26,243.). The above preparation methods have their own advantages, but there are some shortcomings. The above traditional preparation methods mostly use pure zirconium and pure silicon as raw materials, the raw material cost is expensive. Moreover, most of the synthesized products are not single phase zirconium silicide, but the composite materials with zr, zrsi2 and zr2si embedded in the matrix. This method is not easy to control the composition, and it is difficult to prepare the silicon zirconide intermetallic compound with specified composition.
Therefore, it has always been the goal of researchers to find a kind of preparation technology that can synthesize zirconium silicified material with given composition at low temperature and with cheap raw materials.
Include the following steps:
(1) Zirconia, silicon powder and metal reducing agent are added to the reactor, and then heated;
(2) The reaction product is washed, filtered and dried to obtain zirconium silicide nanomaterials.
Further, the molar ratio of the substance between the zirconium dioxide, the silicon powder and the metal reducing agent in step (1) is 1:1:(10-40). Compared with traditional pure zirconium material, zirconium dioxide has low price and low cost.
Further, the metal reducing agent in step (1) is lithium metal or magnesium metal. Lithium metal or magnesium as a reducing agent to promote the reaction, in the process of reaction lithium or magnesium byproduct lithium oxide or magnesium oxide can release a lot of heat, thus reducing the reaction system required heating temperature, so that the application of the reaction conditions more moderate, and less byproduct.
Further, the reactor in step (1) is a stainless steel autoclave.
Further, the heating described in step (1) adopts the way of temperature rise heating, heating to 600-800℃ and maintaining 5-40 hours. The reaction temperature of the proposed preparation method is lower than that of the traditional preparation method, and the reaction conditions are mild.
Further, the heating rate of the heating heating is 5-15℃ per minute. The solvent used for washing is any one or several of distilled water, anhydrous ethanol and dilute hydrochloric acid. The drying temperature is 60-80℃, and the drying time is 2-5 hours.