Research On The Synthesis Process Of Zirconium Boride

Zirconium hydroxide is not only widely used in pigments,glass,fuel and other industries,but also used as adsorbents for medical treatment and sewage treatment in recent years.and It is prepared by sol-gel method and hydrolysis precipitation method,but the current production of precipitation method for zirconium hydroxide has large particle size and filtration difficulty,In the paper,the Zirconium hydroxide is prepared by ammonia gas bubble,the method can control the diameter of nanometer particle,the present invention has the features of simple technological process,easy operation,rich material source and low cost.Zirconium diboride?ZrB₂?has many excellent properties such as high melting point,high conductivity and thermal conductivity,the ultra high temperature ceramic materials have attracted great attention in the application of thermal protection materials,in high temperature composite materials,electrode materials and aerospace field.However,conventional industrial synthesis of zirconium boride is difficult to sinter because of its low particle size and low activity.The zirconium boride was prepared by carbothermal reduction combined with boron thermal in the paper,and the process conditions are optimized,and the particle size of zirconium boride is reduced,which is beneficial to the subsequent sintering performance.This paper is divided into two parts,on the one hand zirconium hydroxide was prepared by Ammonia gas Bubble.And the effects of reaction conditions,reaction temperature,reaction time,aging time and stirring rate,seed and other process conditions on the particle size influence of zirconium hydroxide was studied,On the other hand borothermal reduction co carbothermal reduction synthesis subsection calcination of low impurity content,small particle size,high activity,ultrafine zirconium boride powder have good sintering properties by charactered.The results show the optimal preparation conditions for ultrafine zirconium hydroxide,the reaction temperature is 60?,the concentration of zirconium ion was 1mol/L,reaction time was 4h,aging time was 1h,stirring speed was 1200-1400r/min,when 10%sodium hydroxide was added into the reaction.The particle size of the product reached 30nm,and the purity was 99.3%.and zirconia was prepared by calcine with boron carbide?B₄C?,carbon black?C?and self-made zirconia?ZrO₂?.finer grain size and high purity zirconium boride powder was prepared by blending with carbon/heat borothermic reduction section calcined in vacuum under high temperature.Under optimum processing condition,the reaction was add into excess 25%boron carbide,the temperature at1450?keep a blance for 1h,and the recation is incubated at 1750? for a further 2h.