氢化条件对碳酸锂提纯的影响

以工业级Li2CO3为原料,采用氢化分解法提纯制备较高纯度Li2CO3,研究了氢化温度、CO2气体流速及氢化时间3个氢化条件对碳酸锂提纯过程中纯度、产率以及钙镁杂质去除的影响。结果表明,Li2CO3纯度和产率随着氢化温度的升高而降低,杂质钙、镁的含量随着氢化温度的升高略微增大;CO2气体流速对Li2CO3纯度及钙镁杂质的去除影响不大,产品产率随气体流速的增大而增加;Li2CO3纯度及产品产率随氢化反应时间的延长而增加,氢化时间延长对钙镁杂质的去除无明显影响。     

工艺条件对聚苯胺粉体Ni-Co-P合金镀层的影响

利用化学镀工艺对聚苯胺粉体表面进行金属化改性,使其在雷达波吸收方面具有电损耗的同时兼具磁损耗性能.通过实验获得一组较好的化学镀Ni-Co-P配方,在此基础上讨论主盐浓度、主盐浓度比、镀覆时间等控制对镀层沉积速度的影响因素,研究了镀覆时间对镀层组分的影响.获得了化学镀Ni-Co-P合金的最佳工艺条件为:pH=9、温度85℃、硫酸镍质量浓度18g/L、硫酸钴质量浓度9g/L,此时镀液稳定,沉积速度快.     

碳化分解法制备电池级碳酸锂的研究

以工业级Li2CO3为原料,采用碳化分解法提纯制备电池级纯度Li2CO3。研究了碳化时间、固液比和CO2气体流速3个因素对Li2CO3提纯过程中纯度、产率以及杂质钙镁铁去除效果的影响。最佳工艺条件为碳化时间30min,固液比1∶30,CO2气体流速4L/min。结果表明,通过碳化分解法可使粗级Li2CO3产品的纯度由90%提高到99.75%以上,产率达到78%以上,满足了电池级Li2CO3的要求。     

工艺参数对低温燃烧合成钛酸钡粉体的影响

低温燃烧合成(LCS)钛酸钡粉体的工艺是一种能够直接在低温合成四方相纳米钛酸钡粉的方法。在硝酸盐和柠檬酸体系中,以推进剂化学为理论依据,实验得出各反应物间的最佳摩尔配比,考察了前驱体溶液pH值等对反应过程和最终产物的影响。应用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等对粉体的结构、形貌进行了分析。结果在300℃点火生成晶粒度在100nm左右无杂质相的四方相钛酸钡粉。     

循环氢化对电池级碳酸锂制备中钙镁去除的影响

以工业级Li2CO3为原料,采用氢化分解法提纯制备电池级Li2CO3,研究了母液循环、干料产品循环、湿料产品循环、干料产品和母液循环、湿料产品和母液循环5种循环氢化过程对电池级Li2CO3制备中Ca、Mg去除的影响.结果表明,母液循环氢化3次、干料循环氢化1次、湿料循环氢化3次、干料和母液循环氢化3次、湿料和母液循环4次均可使Ca、Mg杂质有效降低,且Mg含量均控制在电池级Li2CO3行业标准以下;适当次数的湿料循环、干料和母液循环、湿料和母液循环均可以将Ca含量降低到电池级Li2CO3行业标准以下.     

感应等离子体技术制备球形铸造碳化钨粉体及其性能表征

球形碳化钨增强金属基复合涂层具有高硬度、高韧性和优异的耐磨、耐蚀性等特点,可以对材料表面起到有效保护作用。传统铸造碳化钨粉体多呈不规则的片状或多角状,流动性差且硬度低,难以满足高性能涂层材料的要求。本文以多角状铸造碳化钨粉体为原料,采用感应等离子体技术制备球形碳化钨粉体,研究感应等离子体技术工艺参数对碳化钨粉体球化效果的影响规律。采用扫描电子显微镜、X射线衍射仪、霍尔流速计、激光粒度分析仪等对球化处理前后碳化钨粉体的形貌、物相、松装密度、粒度分布进行表征。结果表明:送粉率为110 g/min、载气流量为5.0 L/min时,采用感应等离子体技术可制备颗粒饱满、表面光滑、分散性良好,球化率高达99%以上,且球形度较好的球形碳化钨粉体。球化后碳化钨粉体无孔洞等缺陷,内部组织为典型的细针状WC和W₂C的共晶,组织结构均匀细密。球化后碳化钨粉体的硬度高达3 258HV,提高了408HV;球化后碳化钨粉体的松装密度由8.01 g/cm³提高到9.75 g/cm³,霍尔流速由10.30 s/50 g降低到6.80 s/50 g,粉体的流动性提高。     

利用离心喷雾干燥制备球形粉体的工艺因素研究

研究了铝矾土料浆的离心喷雾造粒过程,考察了料浆固含量、粘度、喷雾头的旋转速度对粉体干燥的影响.从颗粒内部水分迁移的距离、空气进出口温度两方面,分析了蘑菇头颗粒、变形颗粒、球形颗粒和破裂颗粒等颗粒形貌的形成原因,并优化了一组工艺参数:喷雾头转速为12000r/min,料浆固含量为50%,热风入口温度为300℃,废气出口温度为115℃,塔内负压为-350Pa,料浆流速为4L/h,料浆的粘度为14s,在此条件下能制备出球形度高、颗粒粒径集中分布在55μm左右的粉体.     

自蔓燃高温合成工艺参数对制备氮化硅粉体的影响

采用自蔓燃高温合成方法(SHS)合成氮化硅粉体,借助于XRD、SEM等检测方法,分析了自蔓燃高温合成氮化硅过程中氮气、温度、稀释剂与孔隙率等工艺参数对合成产物的影响。结果表明:只要最高燃烧温度不高于相应氮气压力下Si3N4的热分解温度,就可以用SHS方法合成Si3N4;氮气压力下硅粉的自蔓燃合成反应,必须要引入Si3N4稀释剂来控制反应温度,获得高α相Si3N4含量的粉体。压坯气孔率控制在30%～70%,否则反应不能进行。SHS法可以制备纯度很高的氮化硅粉体。     

合成条件对羟基磷灰石粉体形貌和煅烧后组成的影响

通过溶液法制备羟基磷灰石粉体,研究了反应体系与分散剂、溶液浓度、反应温度、pH值和陈化时间等工艺因素对羟基磷灰石粉体粒度和形貌的影响.研究表明,高浓度(1mol/L)乙醇-水溶液条件下,也可通过控制工艺因素获得不同形态(如颗粒状、针状)的羟基磷灰石粉体.粉体煅烧可得仅含羟基磷灰石和磷酸钙的生物陶瓷粉.提高pH值、延长陈化时间可以提高煅烧产物中羟基磷灰石的含量.     

碳酸二苯酯绿色合成工艺的研究

介绍了不同合成工艺制取碳酸二苯酯DPC的基本原理及其特点 ,尤其论述了新型的采用CO和亚硝酸苯酯为原料 ,固相催化合成DPC工艺路线     

Synthesizing a composite material of amorphous calcium carbonate and aspartic acid

A composite material of amorphous calcium carbonate and aspartic acid (Asp) was synthesized using a highly concentrated solution of calcium aspartate: a new approach. A transparent and amorphous solid with approximately 1 mm thickness was obtained. UV-vis transmittance spectrum of the composite shows no characteristic absorption in visible region. A Raman spectrum of the composite revealed a peak assigned to the symmetric stretching of carbonate ion. This study demonstrated that amorphous calcium carbonate could be stabilized using not only organic artificial macromolecules but also using Asp, a small biomolecule. This result is expected to engender development of new biomimetic materials.     

独特形貌碳酸钙的微波水热合成与表征

以醋酸钙和尿素为原料,在无添加剂的条件下采用微波水热法合成技术,直接制得了高度对称的双头矛状、双头扁平铲形、拉长六边形、拉长四边形、侧表面为六边形的多面体和六瓣花状等奇异形貌的碳酸钙晶体,利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅里叶红外光谱仪(FT-IR)等对样品进行了表征,并对碳酸钙晶体的形成过程进行了分析。结果表明醋酸钙用量、尿素用量和微波辐照能量对碳酸钙晶体的结构与形貌具有重要调控作用。     

热重分析对高分子材料中碳酸钙的定量研究

碳酸钙是高分子材料中常用的无机填料，在高温时会同二氧化碳而失重。利用热重分析可准确定出高分子材料中碳酸钙的含量，同时还可测出聚合物，挥发物的含量，热重分析法样品用量小，灵敏度高，所需时间短。     

旋转填充床中合成微细晶须碳酸钙的试验研究

通过试验研究筛选出MgCl2与H3PO4两种在旋转填充床(RPB)中促使微细晶须碳酸钙合成的晶形控制剂,单因素试验探明了各晶形控制剂条件下合成微细晶须碳酸钙的较佳工艺条件,正交试验研究了各因素对粒子长径比影响的显著性.研究表明:与常重力场中合成晶须碳酸钙的方法相比,RPB产生的超重力场中合成晶须碳酸钙反应温度降低约20℃、合成等物质的量晶须碳酸钙所需时间约为其他方法的1/36～1/18、粒子短轴直径达到80～250 nm微细程度;使用MgCl2时只有反应温度对粒子长径比有显著影响,而使用H3PO4时反应温度、RPB转速和气体体积流量对产品粒子长径比均有显著影响.     

Preparation and characterization of novel diatomite/ground calcium carbonate composite humidity control material

Three kinds of novel diatomite/ground calcium carbonate composite humidity control materials were prepared with different calcination temperatures using diatomite and ground calcium carbonate (GCC) as raw materials. The microstructure and morphology properties of samples were studied by nitrogen gas adsorption, mercury intrusion porosimetry (MIP) and fractal dimensions on the basis of gas adsorption isotherms with FHH methods. Fourier transform infrared spectroscope (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the mineral composition and surface properties. Furthermore, X-ray diffraction (XRD), thermo-gravimetry and differential scanning calorimetry (TG-DSC) were used to analyze the formation mechanism of composite material. It was indicated that DG750 showed the better moisture adsorption performance. The 72 h moisture adsorbed amount of DG750 reached 11.66%, 8.81% and 8.00% at 98%RH, 85%RH and 75%RH, respectively, which improved about 0.46, 0.54 and 0.53-fold as those of diatomite. The hydrophilic calcium silicate, calcium oxide and calcium hydroxide were formed in the DG750 during the calcinations process. As compared with the raw materials, the content of mesoporous component increases in the DG750, which is in favor of capillary condensation and improving moisture adsorption ability.     

Surfactant assisted synthesis of precipitated calcium carbonate nanoparticles using dolomite: Effect of pH on morphology and particle size

Synthesis of nanomaterials from readily available minerals for industrial applications is a growing research area. Understanding the causes of their properties becomes handy in utilization. In this study, an effective sucrose solution based method was employed for the extraction of calcium from dolomite to synthesize precipitated calcium carbonate nanostructures with different morphologies and sizes. It was found that 30% (w/v) sucrose solution extracted approximately 91% of calcium from dolomite forming a calcium-sucrate complex. Carbonation was achieved by CO₂ bubbling and aqueous sodium carbonate addition. Precipitation was performed under different pH values of 7.5, 10.5 and 12.5 in the absence of an anionic surfactant and in the template of sodium dodecyl sulfate (SDS)/calcium-sucrate at pH 12.5. It was found that CO₂ bubbling slightly promotes smaller particles. The anionic surfactant enables particle size and agglomeration reduction while introducing some hydrophobicity. The smallest particles were achieved at a range of 40–55 nm in the presence of SDS/sucrose template and were of spherical morphology. By changing the pH, a tendency to form different polymorphs and shapes of calcium carbonate was observed.     

基于碳酸盐定量分析的水泥石抗碳化性能测试方法

针对目前各种碳化深度测量方法的弊端,结合所发明的检测装置,形成了一套新型抗碳化性能测试方法一碳酸盐含量法.试验结果表明,这是一种更加精确的碳化测试方法,不仅能划分完全碳化区和碳化进行区,还不会因受到其它水泥石中性化因素的干扰而影响测量结果.基于试验结果,对比酚酞喷涂法,说明该方法更具有优势,不但原理简单,而且可以测得试...     

Synthesis of ultra-small hollow silica nanoparticles using the prepared amorphous calcium carbonate in one-pot process

The ultra-small hollow silica nanoparticles were synthesized using the prepared amorphous calcium carbonate (ACC) particles as a template. The ACC particles were firstly prepared by carbonation method, which procedure was conducted in the methanol solvent to form the Ca(OCH₃)₂ layers on the ACC particles. An effect of methanol concentration on the morphology of ACC particles was also investigated. The prepared ACC particles were directly coated by silica through adding tetraethoxysilane (TEOS) into the methanol solvent. Hence, the ACC-silica core-shell particles were obtained since the ACC particles have a positive charge and interact with hydrolyzed TEOS. The ACC particles could be stabilized through the reaction between methanol and calcium ions when the methanol concentration was increased over than 40?vol%.     

快速测定工业沉淀碳酸钙中的铁和锰

采用测定盐酸不溶物后的溶液代替单独称样、溶样、过滤、洗涤、定容后的滤液测定铁和锰。本方法可以快速准确测定铁、锰,工作效率大大提高。