Preparation Of Porous Calcium Titanate And Its Study Of Calcium Heat Reduction

Porous metal titanium,which has properities of titanium and metal foam,was used as structural materials and functional materials,and it has a wide range of application prospect.The investigation of preparation of porous titanium and structural performance has become one of the research hotpots.In this paper,metallurgical material integration conception,which was based on the review of the research status of porous titanium preparation at home and abroad,was put forward for the preparation of metallic titanium powder and porous titanium by calciothermic reduction of porous calcium titanate.Synthesis calcium titanate,preparation of calcium titanate and its reduction by calcium vapor were investigated by means of thermodynamic calculation and XRD,SEM,EDS,HR-TEM,BET,Hybrid real color confocal microscopy and infrared microscopy.The thermodynamic calculation results of synthesizing calcium titanate showed that when the sintering temperature was higher than 1073K,the CaO produced by decomposition of CaCl2·2H2O reacted with TiO2 to promote the conversion of TiO2 to CaTiO3.The experimental results showed that when mass ratio of MCaC12.2H2O/MTiO2 ?2:1,holding temperature was higher than 1073K and preservation time was greater than 2 h,the CaTiO3 crystal could be completely synthesized.According to SEM observation,the crystalline CaTiO3 powders were mainly composed of many separated particles with average size approximately 10 ?m and had been demonstrated a strongly faceted morphology.The lattice plane,(112)was clearly observed in the HR-TEM micrograph and the lattice distance was measured as 0.27 nm.The results of porous CaTiO3 synthesis experiments showed that the pore size of the synthesized porous calcium titanate did not change with the increase of the heating rate.However,that with the increase of CaCl2·2H2O was as follows:(1)From the statistical average pore size point of view,the porous calcium titanate aperture had increasing trend with the amount of CaCl2·2H2O,but not obvious;(2)According to the BET test of micropores,when the ratio MCaCl2.2H2O/MTiO2 was less than 1.5:1,the pore size almost did not change.When the mass ratio of MCaCl2.2H2O/MTiO2 was greater than 1.5:1,the pore size was obviously smaller.The conditions for synthesis of porous calcium titanate were:the heating rate of 10K/min,MCaCl2.2H22O/MTiO2 is 2:1,the holding temperature is more than 1073K and the holding time is more than 2h.The reduction thermodynamic calculation of CaTiO3 showed that CaTiO3 was easily reduced by calcium vapor at a vacuum degree of 20 Pa,and the reduction reaction was exothermic reaction.From the reduction results,the reduced product was leached to obtain metal porous titanium and metallic titanium powder,the percentage of porous titanium is 18%,genetic small hole diameter of the porous titanium is distributed between 5 and 20 ?m;and that of genetic big pores from 20 to 100 ?m.It was available from Hybrid real color confocal microscopy and infrared microscopy analysis that the thickness of porous titanium was about 150 ?m and has a three-dimensional structure.The porous titanium was mainly formed on the interface layer of the product.It was due to the presence of molten metal calcium on the interface layer of the product and the reduction reaction was an exothermic reaction which resulted in metal titanium particles were sintered at the interface layer of product into porous titanium.