纳米TiO_2水分散体系稳定性的研究

研究了不同类型的分散剂对金红石型纳米TiO2在水中分散体系稳定性,探讨了分散剂、偶联剂用量、纳米TiO2浓度及pH值对纳米TiO2水分散体系的影响。结果表明,最佳分散剂为SK-5040,最佳分散条件为:100 mL纳米TiO2水溶液中,最佳分散剂用量为1.0 g,KH-570硅烷偶联剂用量为1.5 mL,纳米TiO2浓度为1.0%,pH值为10。     

消光PA 66生产用TiO2水悬浮液分散稳定性的研究

采用悬浮沉降的方法研究了不同的分散剂添加量、不同的固体浓度、不同的温度下,TiO2颗粒在水中的分散稳定性,利用静电稳定机制和空间稳定机制解释了各种因素对TiO2水悬浮体系分散稳定性的影响。     

纳米TiO_2在有机相中的分散性研究

以环己烷作为有机溶剂,利用超声细胞破碎仪打散团聚粒子,通过静置试验、分光光度法和TEM测试,研究了纳米TiO2在有机相中的分散性,探讨了分散剂对其分散稳定性的影响,并分析了分散剂的作用机理。研究结果表明,选择适合的分散剂的种类及添加量,可制备出在环己烷中稳定分散的纳米TiO2分散体系。     

正交设计法制备纳米TiO2改性涂料

针对纳米TiO2在涂料中不易分散且分散稳定性差,易发生二次团聚的问题,根据纳米粒子的团聚及分散原理,利用正交设计方法,研究了纳米TiO2含量、乳液配比、分散剂用量及超声分散时间对涂料性能的影响,确定了最佳配方。     

利用多重光散射法对纳米TiO2水分散体系稳定性研究

通过多重光散射法研究了纳米TiO2水分散体系稳定性的影响因素。文章探讨了分散剂类型、pH和NaCl质量浓度对水分散体系稳定性的影响规律以及分散剂对纳米TiO2颗粒在水分散液中粒径变化、沉降的微观作用特性。结果表明：纳米TiO2颗粒的粒径在100～200 nm时易相互吸附团聚沉降,分散剂会在纳米TiO2颗粒表面吸附形成双电层,产生更大Zeta电位负值,增强颗粒间的排斥作用,减缓粒径增长和发生沉降的作用,从而提升分散液稳定性;纳米TiO2颗粒的较佳分散条件为：w(六偏磷酸钠)=0.05%,pH=9～10且不加电解质NaCl;多重光散射法与传统的吸光度测试实验所得结果基本相符。     

纳米氧化钛粉体水基分散体系的研究

采用悬浮沉降法研究了不同分散剂、不同分散介质和不同搅拌方式以及不同的固含量对纳米TiO2粉体在水中的分散稳定性的影响,采用透射电镜的方法表征纳米氧化钛在水中的分散状态,并解释了各种因素对TiO2水基分散体系分散稳定性的影响机制.     

分散剂对纳米TiO2悬浮液稳定性的影响

选择不同的有机物为分散剂分别对纳米TiO2粒子进行了表面改性。通过采用重力沉降法、Zeta电位法等表征了其分散效果,研究了纳米TiO2悬浮液在不同PH值下的分散行为。结果表明:纤维素能使纳米TiO2悬浮稳定性明显提高。在纳米TiO2悬浮液中,纳米TiO2粉体表面的Zeta电位同水溶液的平衡PH有很大关系。提高颗粒表面电位(Zeta电位)是改善粉体分散体系稳定性的有效途径。     

纳米TiO2水性分散浆的制备研究

采用悬浮沉降法研究了几种分散剂对纳米TiO2粉体在水中分散稳定性的影响.结果发现,分散剂种类和用量对粉体的分散性影响很大,将分散剂按一定的比例复配使用,分散效果显著提高.     

纳米TiO2颗粒在制冷工质中的分散

纳米TiO2颗粒在制备和应用过程中极易团聚,解决其分散问题是纳米TiO2颗粒在制冷系统中应用的基础和前提. 本工作利用目测沉降观察、分光光度计吸收测量法和激光粒度分析法,实验研究了纳米TiO2颗粒在制冷工质中的分散特性. 结果表明,纳米TiO2颗粒在制冷剂中分散较稳定,制冷剂介电常数和极性是主要的影响因素;Span-80可以作为纳米TiO2颗粒在制冷剂中的分散剂;温度对纳米TiO2颗粒在制冷剂中的分散稳定性影响明显. 研究结果可为纳米TiO2颗粒在制冷系统中的应用研究提供基础数据.     

纳米TiO_2在水中的分散与改性研究

为了使纳米TiO2能在水中良好稳定地分散,研究了分散剂的种类及用量、pH、改性剂的用量对纳米TiO2水分散体系稳定性的影响,采用重力沉降法、吸光度法、粒度法、Zeta电位法对分散与改性效果进行了分析与表征。研究结果表明:无机分散剂六偏磷酸钠(SHMP)对纳米TiO2的分散效果最好,当pH=9,SHMP用量为0.05 g时水分散体系稳定性最佳。硅烷偶联剂Z6030能有效地对纳米TiO2进行改性,其最佳用量为0.4 g,动态激光光散射(DLS)和傅里叶变换红外光谱(FT-IR)测试结果表明,硅烷偶联剂Z6030与纳米TiO2粒子表面的羟基相耦合或链接,以化学键的形式结合到纳米TiO2粒子表面。     

Ultrasonic dispersion of nano TiC powders aided by Tween 80 addition

Nano TiC powders were dispersed in aqueous media. Effects of ultrasonic treatment and Tween 80 addition on dispersion of TiC powders were investigated. The results showed that ultrasonic treatment had a large effect on the dispersion of nano TiC powders, and 30 min of ultrasonic treatment was necessary for fine dispersion from TEM images and particle size measurement. Tween 80 was selected as the dispersant. Sedimentation test indicated that 0.5 vol.% was the optimum addition level of Tween 80 in TiC suspension. FTIR spectrum proved the adsorption of Tween 80 on the surface of nano TiC powders. XPS analysis revealed the existence of TiO₂ on the TiC powder surface, which led to a hydroxylated surface during dispersion. In the presence of Tween 80 in the solution, zeta potential values became more negative. Both electrostatic stabilization and steric stabilization were deduced to be the main mechanisms for well dispersion of the nano TiC powders in aqueous media.     

Dispersion behaviour of laser-synthesized nanometric SiC powders in aqueous medium with ammonium polyacrylate

The dispersion behaviour of laser-synthesized nanometric SiC powders in water using ammonium polyacrylate (molecular WEIGHT=10,000) as dispersant was investigated. The influence of oxidation, presoaking time, ammonium polyacrylate (NH₄PA) concentration, and pH on suspension stability and coagulation rate of aggregates was determined. The stabilization mechanism is discussed. Excellent dispersion stability was obtained for oxidized (500 °C) powders containing 2.45 wt.% NH₄PA at pH 9.25 after a lengthy aging treatment.     

Effects of dispersant concentration and pH on properties of lead zirconate titanate aqueous suspension

Lead zirconate titanate (PZT) aqueous suspensions were prepared at 60 wt.% solids loading using a commercial ammonium polyacrylate (APA) dispersant. Effects of the dispersant concentration on rheological behavior, dispersion and stability of PZT aqueous suspensions were investigated by means of zeta potential, viscosity and sedimentation height measurements. The results showed that, under suitable conditions, APA dispersant promoted particle dispersion and stabilization in PZT aqueous suspensions. For 60 wt.% solids loading suspensions, the dispersant concentration yielding the lowest viscosity was 0.5 wt.% based on PZT powder dried weight basis. Effects of pH on particle dispersion in the suspensions prepared with APA were studied by laser light scattering technique and scanning electron microscopy. The results showed an improvement in particle dispersion for the alkaline condition, which led to relatively low viscosity and highly stable suspension. Possible particle stabilization mechanisms at various pHs were discussed based on dissociation of the dispersant in water, polymer conformation and adsorption behavior of the dispersant on the particle surface.     

分散剂用量对钛酸锶钡水基浆料稳定性的影响

使用聚甲基丙烯酸铵(ammonium polymethacrylate,PMAA-NH4)作为分散剂,研究了不同pH值条件下分散剂用量对钛酸锶钡(Ba0.6Sr0.4TiO3)水基浆料稳定性的影响,并分析了其影响机理.结果表明:PMAA-NH4的加入能够显著提高Ba0.6Sr0.4TiO3粉体的zeta电位,在加入量(质量分数,下同)为0.4%时,zeta电位为负值,达到最小,从而提高了Ba0.6Sr0.4TiO3水基浆料稳定性.在pH值小于8时,会发生Ba0.6Sr0.4TiO3料浆中的Ba2 和Sr2 离子溶出;pH值大于8时,Ba0.6Sr0.4TiO3粉体的zeta电位随PMAA-NH4的加入量的增加而增大.在pH值为8～9,PMAA-NH4的加入量为0.4%时,实现Ba0.6Sr0.4TiO3粉体对PMAA-NH4的饱和吸附,此时浆料的稳定性最好.     

Dispersion and properties of zirconia suspensions for stereolithography

Stereolithography is an attractive technique for the fabrication of complex-shaped ceramic components with high dimensional accuracy. One of the challenges in this technology is the development of high solid loading, low viscosity photosensitive ceramic suspension. In this study, the dispersion of zirconia in photocurable resin and the slurry properties were intensively investigated. Rheological measurements showed that DISPERBYK-103 proved to be an effective dispersant. 42 vol% ZrO₂ suspension was successfully prepared using 3.5 wt% DISPERBYK-103 as the dispersant, with a suitable viscosity (4.88 Pa·s) below the maximum allowable viscosity value (5 Pa·s) for stereolithography applications. The adsorption behavior of DISPERBYK-103 on the surface of zirconia powders was characterized by TG and FT-IR, confirming the dispersion effect of dispersant. Contact angle measurements were also conducted to show that the adsorption of DISPERBYK-103 could help to improve the wettability between powder and photocurable resin. Results showed that DISPERBYK-103 was effective for the preparation of suitable slurries for the development of ZrO₂ ceramics through stereolithography.     

氧化铝粉体在水悬浮液中的分散特性研究

采用Zeta电位表征Al_2O_3粉在悬浮液中的分散特性,研究了超声波分散时间、不同粒度Al_2O_3粉以及分散剂六偏磷酸钠的浓度和Al_2O_3粉体悬浮液pH值对Al_2O_3粉体Zeta电位的影响.研究结果表明:Zeta电位绝对值随超声波作用时间发生明显变化,在一定条件下存在一个最佳分散时间为4～6 min;悬浮液中Al_2O_3粉体颗粒的粒度对悬浮液的Zeta电位有重要影响;在Al_2O_3粉体悬浮液中添加分散剂六偏磷酸钠,Zeta电位随其浓度发生变化,存在一个最佳浓度0.5%;在不同pH值下,Al_2O_3粉体悬浮液的Zeta电位不同,在碱性条件下,粉体的分散性较好,且碱性越强,分散性越好.     

Roles of polymeric dispersant charge density on lead zirconate titanate aqueous processing

Poly(acrylic acid) (PAA) and poly(acrylic acid-co-maleic acid) (PACM) were used as dispersants in preparation of lead zirconate titanate (PZT) aqueous suspensions. The effects of dispersant structure on particle stabilization were investigated through properties of the suspensions. Viscosity and sedimentation height measurements showed that addition of the dispersants improved particle stabilization. The dispersant concentrations to obtain the lowest viscosity were 0.4 wt% for PAA and 0.2 wt% for PACM based on powder dried weight basis. Furthermore, effects of pH were studied on the suspensions prepared with 0.2 wt% dispersants. Viscosity and sedimentation behaviors indicated the improvements of particle dispersion and suspension stability with an increasing pH. Particle dispersion revealed by laser light scattering and scanning electron microscopy supported an improvement of particle dispersion at alkaline pHs. Detailed analysis of these data indicated that the PACM exhibited higher dispersant efficiency for PZT aqueous suspension in all conditions. The results were discussed based on the concentrations of anionic –COO^? groups at various pHs and charge density along polymeric backbone of the dispersants.     

AlN水基注凝成型浆料的流变性能

以低聚磷酸酯盐H3204为分散剂、Y2O3为烧结助剂,制备高固含量的AlN注凝成型浆料。考察pH、分散剂添加量、固含量对AlN水基注凝成型浆料流变性能的影响。结果表明:当浆料的pH为8.5,分散剂质量分数为0.9%时,制备了固含量(体积分数)为50.8%的AlN水基注凝成型浆料。浆料具有较好的流动性,适于注凝成型。