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硫酸钡为内核的金红石型复合二氧化钛制备研究

发布时间:2019-02-16 08:18
【摘要】:金红石型Ti O2具有较高的介电常数,常作为介电常数调节剂用于高频微波基板材料的制备中,若直接使用微米级Ti O2将造成钛资源的浪费。本文以Ti Cl4为钛源,以合成Ba SO4为内核,采用加热水解工艺在较低煅烧温度下制备出Ba SO4/金红石型Ti O2复合材料,实现了资源利用的最大化。该工艺具有原料价格便宜、流程简单可控、生产能耗低等优点,为金红石型复合Ti O2的工业化生产提供了理论与实践依据。本文的主要内容如下:(1)粒度分布窄的微米级近球形Ba SO4内核的制备首先,以Ba Cl2为钡源,选择不同沉淀剂,分别采用直接沉淀法、均匀沉淀法和EDTA络合沉淀法制备Ba SO4内核,系统考察了反应温度、反应物浓度、体系p H、加料速度、陈化时间对沉淀粒度、粒度分布以及形貌的影响,并对不同方法进行优化。SEM与粒度分析结果表明,只有直接沉淀法中的H2SO4路线与EDTA络合沉淀法制得的Ba SO4颗粒基本符合基板用复合Ti O2对内核的要求,但前者所得Ba SO4存在粒度分布宽、较大颗粒形貌不规则等不足。相比之下,EDTA络合沉淀法能同时实现对沉淀粒度以及形貌的有效控制,最优工艺条件为:室温(25 oC)下,络合体系p H为8,Ba Cl度为0.20 mol/L,络合比为1,Na2SO4浓度为0.25 mol/L,Na2SO4加料速度为5 m L/min,反应时间1 h。在该反应条件下,无需陈化,即可得到粒度分布均匀的球形Ba SO4,平均粒度为1.2μm。然后,比较了直接沉淀法与EDTA络合沉淀法所得Ba SO4内核在相同包覆工艺下的Ti O2包覆效果,结果表明,EDTA络合沉淀法制得的Ba SO4更利于Ti O2包覆,是复合Ti O2内核的最佳选择。(2)金红石型复合Ti O2的制备首先探究水解体系初始p H、水解温度、硫酸根离子和煅烧温度对单一Ti O2颗粒晶型的影响,确定出Ti Cl4加热水解法制备金红石型Ti O2的工艺;然后在上述工艺的基础上,以最优条件下EDTA络合沉淀法制得的Ba SO4为内核,进一步考察水解时间、水解温度、Ti Cl4用量、水解混合液中钛浓度对包覆效果的影响。最终,确定了加热水解法制备Ba SO4/金红石型Ti O2复合粉体的最优工艺条件:水解体系初始p H为0.1,水解混合液中钛浓度为0.20 mol/L,Ti Cl4用量n(Ti Cl4):n(Ba SO4)为2,水解温度80 oC,水解时间1.5 h,煅烧温度500 oC,煅烧时间2 h。在该工艺条件下,复合Ti O有金红石型包覆层,且包覆率高,包覆层均匀致密,此外还具有球形形貌良好、分散性佳等优点。
[Abstract]:Rutile Ti O2 has a high dielectric constant. It is often used as a dielectric constant regulator in the preparation of high frequency microwave substrate materials. The direct use of micron Ti O2 will lead to a waste of titanium resources. In this paper, Ba SO4/ rutile Ti O 2 composites were prepared by using Ti Cl4 as titanium source and Ba SO4 as core. Ba SO4/ rutile type Ti O 2 composites were prepared under low calcination temperature by means of heating hydrolysis process, thus maximizing the utilization of resources. The process has the advantages of cheap raw material price, simple and controllable process and low energy consumption. It provides a theoretical and practical basis for the industrial production of rutile composite Ti O2. The main contents of this paper are as follows: (1) the preparation of micrometer near-spherical Ba SO4 core with narrow particle size distribution. Firstly, the direct precipitation method was used to select different precipitators with Ba Cl2 as the source of barium. The Ba SO4 core was prepared by homogeneous precipitation method and EDTA complex precipitation method. The effects of reaction temperature, reactant concentration, system pH, feeding rate, aging time on the particle size, particle size distribution and morphology of Ba SO4 were investigated. The results of SEM and particle size analysis show that only the Ba SO4 particles prepared by H2SO4 route and EDTA complexation precipitation method basically meet the requirements of the core of composite Ti O2 for substrate. However, the Ba SO4 obtained from the former has some shortcomings, such as wide particle size distribution and irregular morphology of larger particles. In contrast, the EDTA complex precipitation method can effectively control the particle size and morphology of the precipitate at the same time. The optimum conditions are as follows: at room temperature (25 oC), the complex system p H = 8o Ba Cl degree is 0.20 mol/L, complex ratio, and the optimum process conditions are as follows: at room temperature (25 oC), the complexation ratio of pH to Ba is 0.20 mol/L,. The concentration of Na2SO4 is 0.25 mol/L,Na2SO4, the feeding rate is 5 mL / min, the reaction time is 1 h. Under this reaction condition, the average particle size of spherical Ba SO4, with uniform particle size distribution is 1.2 渭 m without aging. Then, the Ti O 2 coating effect of Ba SO4 core obtained by direct precipitation method and EDTA complexation precipitation method was compared. The results showed that the Ba SO4 prepared by EDTA complex precipitation method was more favorable to Ti O 2 coating. (2) the preparation of rutile composite Ti O _ 2 first investigated the effects of initial pH, hydrolysis temperature, sulfate ion and calcination temperature on the crystal morphology of single Ti O _ 2 particles. The process of preparing rutile Ti O 2 by Ti Cl4 heating hydrolysis was determined. On the basis of the above technology, the effects of hydrolysis time, hydrolysis temperature, amount of Ti Cl4 and concentration of titanium in hydrolysis mixture on the coating effect of Ba SO4 prepared by EDTA complexation precipitation under the optimum conditions were further investigated. Finally, the optimum conditions of preparing Ba SO4/ rutile Ti O 2 composite powder by heating hydrolysis method were determined: the initial pH of hydrolysis system was 0.1, and the concentration of titanium in hydrolysis mixture was 0.20 mol/L,. The amount of Ti Cl4 was 2, the hydrolysis temperature was 80 oC, the hydrolysis time was 1.5 h, the calcination temperature was 500 oC, the calcination time was 2 h. Under this condition, the composite Ti O has rutile coating with high coating efficiency, uniform and dense coating layer, good spherical morphology and good dispersion.
【学位授予单位】:江南大学
【学位级别】:硕士
【学位授予年份】:2015
【分类号】:TQ134.11

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