| Zirconium diboride ceramics have been put into application in the fields such as high temperature structural ceramics composites refractories and nucleus-controlling materials, owe to their excellent properties, as high melting point high bending strength high hardness super conductivity for heat and electricity and capbility of neutron-controlling. In this paper, three reaction systems, Zr-B, Zr-B203-Mg, Zr02-B4C-C, were used to synthesise ZrB2 ceramics powder by employing self-propagating high-temperature synthesis (SHS) or solid reaction. In addition, the mechanism and discipline of chemical reaction and microstructure formation process of SHS were studied. Furthermore, ZrB2 ceramics were sintered with hot-pressing method.The results of analysis of Differental Scanning Calorimetry analysis (DSC) and X-ray diffraction (XRD) showed following thermodynamic process of Zr-B2O3-Mg system. The absorptive water of raw mixture was dehydrated at about 120 and 170, and B2O3 was melted at 450 . The vehement exothermal reactions were happened between Mg-B2O3, Zr-B2O3 and Zr-B systems at about 643 , in this process, 8203 was reduced by Mg and Zr powder to element B and metal Mg was melted and transferred into liquid phase at 650 . At 720 The more vehement exothermal reactions were happened, including B2O3+Zr+3Mg-ZrB2+3MgCK B2O3+2Zr+Mg-ZrB2+MgO +ZrO2 and all the possible above-mentioned reactions.The results of analysis of SHS experiment and dynamics indicated that the SHS product from Zr-B was a single-phase of ZrB2, but those from Zr-B2O3-Mg system were the ternary phase mixture of ZrB2 , MgO and ZrO2. For Zr-B2O3-Mg system, the ideal reactants were 300 mesh Zr powder and excessive 15% Mg powder.Results of microstructure formation suggested that (1). Zr-B system: the Zr powder was surrounded by fine B powder. The B powder was heated first and then the B powder conducted heat to the Zr powder. The vehement exothermal reaction was happened and ZrB2 was synthesized when the temperature was enough high. (2). Zr-B2O3-Mg system: the Zr and Mg powder were surrounded by fineB2O3 powder. The vehement exothermal reactions were happened between Mg-B2O3 Zr-B2O3 and Zr-B systems 'at about 643 , in this process, The particle of Mg and Zr were the base of product and nucleus growth. The ternary phase of ZrB2 MgO and ZrO2 formed a mixture. At 720 The more vehement exothermal reactions were happened, including the reaction B2O3+Zr+3Mg ZrB2+3MgO B2O3+2Zr+Mg-ZrB2+MgO +ZrO2, the new product would be come into being on the surface of the above product, and formed a ternary phase mixture.In Zr-B system, the outcome of SHS reaction included ZrB2(98.95%)x Zr(1.05%).After acid-leaching towards the SHS product of Zr-B2O3-Mg, the particles were circles or oral, and their sizes were about 0.5-2 u m. The majority were about 4-8 u m. There were 26 47 64 percent of them under 4 u iru 6 u m 8fm respectively. The leached product consisted of ZrB2(94.59%) ZrO2(3.87%) H3BO3(1.54%). In the synthesizing of ZrB2 ceramics powder from ZrO2-B4C-C, the reaction system of the excessive 15% 840 and the excessive 10% C were the best raw mixture.ZrB2 ceramics were sintered by hot pressing, and the densification mechanism during the sintering process was studied. It was found that initial sintering law agreed with materials transfer by plastic flow, and the following sintering law was coincident with materials transfer by diffusion and creep. In sintering process, the ZrB2 ceramics can be fabricated under following sintering conditions: temperature: 2073K, pressure: 30MPa, time: 2 hour.The particle size of sintered product from ZrO2-B4C-C is about 13 u m and the relative density is 94%. The element analysis of the production proves that it was a mixture of ZrB2(95.44%) ZrO2(3.87%) B4C(0.32%) C(0.37%).The leached product of Zr-B2O3-Mg can be sintered by adding proper B4C and C. The grains of the sintered product with the relative density of 95.4% looked regular and were about 2-10um.
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