片状纳米银粉的化学制备技术研究进展

片状纳米银粉的化学制备技术备受人们关注。本文综述了片状纳米银粉的化学还原沉淀法、软模板法、电化学沉积法、热沉积法等化学制备技术,探讨了化学法制备片状纳米银粉的形成机理。片状纳米银粉由于表面效应和量子尺寸效应表现出独特的光、热、电、磁、催化等性能,在导电、杀菌、催化、生物等方面得到广泛的应用。片状纳米银粉的化学制备技术显示出诱人的发展前景。     

超声处理对片状氧化铝粉体分散性能的影响

本文以氧化铝粉体为原料,氟化铝为添加剂,基于高温固相法制备了片状氧化铝粉体,并研究了氟化铝的含量分别为2.5 wt%、7.5wt%和15 wt%时氧化铝粉体形貌的变化,结果显示随着氟化铝含量的增加片状氧化铝粉体团聚现象减少,无规则氧化铝颗粒减少,片状氧化铝增多;同时使用超声破碎仪对其进行处理,并考察超声时间分别为10 min、30 min、60 min和超声功率分别为25%、50%和75%时对粉体分散性能的影响,结果显示超声功率为75%,超声时间为60 min时,片状氧化铝粉体团聚现象消除,具有良好的分散性。     

Al-MgAl_2O_4和Al-MgO-MgAl_2O_4体系中生成MgAlON的形貌

为研究镁质原料对金属复合耐火材料中原位生成MgAlON形貌的影响,以金属Al粉为金属相,富铝尖晶石粉和电熔镁砂粉为镁质原料,固定Al粉加入量为30%(w),镁砂加入质量分数分别0、10%和30%(则镁铝尖晶石粉加入质量分数相应为70%、60%和40%),在埋炭条件下于1 350℃保温2 h烧后,利用SEM观察AlMgAl_2O_4和Al-MgO-MgAl_2O_4体系的试样中生成MgAlON相的显微形貌,并通过热力学分析探讨不同形貌MgAlON相的生成机制。结果表明:不加镁砂的Al-MgAl_2O_4体系中生成了板片状的MgAlON相,其形成机制为镁铝尖晶石参与反应的固-液-气或固-气反应。在加镁砂的Al-MgO-MgAl_2O_4体系中,加入少量(质量分数10%)镁砂时,生成了粒状和片状的MgAlON;镁砂加入量较多(质量分数30%)时,生成了粒状MgAlON,其形成机制为气-气反应,同时粒状MgAlON的粒径随着镁砂粉加入量的增多而增大。     

散粉扫描电镜和能谱仪观察及成分分析

以某品牌散粉为研究对象,利用扫描电镜试验(SEM)和X射线能谱仪(EDS)对散粉的形貌以及成分进行测定,分析了该散粉的微观形貌和组成成分。实验结果表明:该散粉主要以球状颗粒(成分分析为二氧化硅小球)和片状颗粒(成分分析为滑石粉)组成,且片状颗粒占主要成分。     

专利介绍

<正>高温可修复导电胶CN103 666 316(2014-03-26)。该导电胶(以质量分数计)由环氧树脂100%、片状银粉700%、固化剂30%、固化促进剂15%、聚甲基丙烯酸酯微粉[平均粒径≤6μm,玻璃化转变温度(Tg)<156℃]20%、熔点为156℃左右的铟粉2%和偶联剂15%等组成。与现有技术相比,该导电胶以聚甲基丙烯酸酯微粉和铟粉替代了现有自修复型导电胶中所用的微胶     

紫外光固化聚氨酯基导电银浆的制备及其性能研究

以超细球银与片状银粉复配作为导电相,二官能度的端乙烯基聚氨酯丙烯酸酯预聚物作为粘结相,制备出高电导率、高附着力和高柔韧性的紫外光固化聚氨酯基导电银浆。研究了超细球银与片状银粉的相对用量对银浆电导率、附着力和耐弯折性能的影响,并通过扫描电镜对银浆中银粉的分散状态进行了分析。结果表明:采用适量的超细球银与片状银粉复配,可以有效提高银浆的电导率和力学性能。当超细球银用量为6.6%(wt),片状银粉用量为65%(wt)时,银浆的电导率高达1.33×106S/m;与聚对苯二甲酸乙二醇酯基材具有良好的附着力,百格测试级别为5B;耐弯折性能优良,10次弯折测试后,电导率仍能达到3.38×105S/m。     

片状氧化铝粉体的熔盐法合成

片状氧化铝由于其独特的片状结构,在珠光颜料、化妆品、填料及抛光粉等领域得到了广泛的应用.本文采用熔盐法制备了片状氧化铝粉体,考察了熔盐种类和熔盐用量对粉体形貌的影响.以硫酸铝为铝源,复合硫酸盐(Na2SO4+K2SO4)为熔盐,辅以外加添加剂,合成出了厚度为200～400 nm,平均径厚比约为50的形貌较好的片状氧化铝.     

六方片状氧化铝微晶的制备及生长过程研究

片状氧化铝具有热容量大、导热率高、热稳定好、耐高温、抗腐蚀以及极小的厚径比,广泛应用于催化剂基体或载体、机械抛光粉、橡胶或树脂的添加剂和陶瓷增韧剂等领域。以AlF₃为矿化剂,结合机械力化学作用对无定形Al₂O₃进行处理,研究了AlF₃和机械力化学对六方片状氧化铝形成的影响,探讨了片状氧化铝的生长机理。结果表明：随着AlF₃用量的增加,α-Al₂O₃的片化程度逐渐增加,最终形成多维团聚,制备单分散片状α-Al₂O₃微晶的最佳AlF₃质量分数为3%;随着球磨时间增长,有利于得到六方片状α-Al₂O₃微晶,处理4 h后开始出现明显六方片状微晶。片状氧化铝的生长符合螺旋位错生长机理;随着保温时间增长,生长后期氧化铝颗粒更倾向于借助大尺寸片状微晶表面位错生长,从而形成多维团聚。     

导电涂料

、导电涂料1996年将含片状Ag粉和球状Ag粉的混合物与含合成聚合物和有机溶剂的基料捏和,再加人0.01一8份(以20一80份Ag粉混合物为基准计)吠喃甲酸(I)制成的。例如,将Pl洲一4348和PIJ-2207(酚醛树脂)11.10份、乙二醇单乙醚22.20份、1,1的片状Ag粉一Ag包膜的球状Cu粉混合物“.7份和10.30份捏和,制得一种触变性涂料(固化时间成15min),其电阻率为Zx10’5。。该涂料具有良好的贮存稳定性。9605174涂料用的导电聚合物一聚氨醋混合物:EP630951〔欧洲专利公开〕/BASFA一G.(Sauerer,Wolfgang等)一1994.12.28一14页一DE 4321001(1993.6.24);…     

FM型风选磨在矿渣预粉磨工艺中的应用

1 传统矿渣粉磨的工艺技术难点 现有矿渣粉磨大厂采用立磨粉磨,粉磨电耗50～55k、Wh,中小厂大多采用传统管磨粉磨,粉磨电耗65～70kWh/t.由于立磨粉磨颗粒形貌为片状和针刺状,活性差,管磨粉磨颗粒形貌为球形状,活性好,因此矿渣粉磨大多采用管磨粉磨.     

片状铜粉化学镀锡的工艺研究

采用次磷酸钠作还原剂,在片状铜粉表面化学镀锡,得到片状锡包铜粉。研究了镀液pH、温度、还原剂、稳定剂以及主盐浓度等对锡包铜粉性能的影响规律,研究了锡包铜粉的成分和表面形貌。结果表明:通过控制工艺参数可以获得镀覆质量好,且具有很好导电性和低松装密度的片状锡包铜粉产品。     

无机粉体形状对微发泡聚丙烯材料发泡行为的影响

选取粒径约为20μm的针状MgSO4晶须、片层状云母粉和粒状SiO2,以5%的用量加入到聚丙烯(PP)中,在二次开模条件下制备微发泡PP复合材料;通过异相成核理论和粉体分布的特性,分析了无机粉体形状对微发泡PP复合材料发泡行为的影响。结果表明,片层状云母粉具有良好的相容性、比表面特性和异相成核作用,发泡效果理想;泡孔直径达到22.10μm左右、泡孔密度为6.92×108个/cm3;聚烯烃类材料发泡的成核剂中,以片层状的云母粉较为理想。     

Hydrophobic Nano‐Silica for the Surface Modification of Graphite Flake

Graphite flake is an electromagnetic interference material of importance for IR screening. In this study, an attempt to improve the performance of graphite flake by coating it with nano‐silica using cyclomix (Hosokawa) and hybridizer (Nara) processes was made. Uncoated and coated graphite flakes were examined by scanning electron microscopy (SEM). It was shown that a more uniform coating was obtained using the hybridizer process. Coated graphite flake with a mass ratio of nano‐silica equal to 5.25 % exhibited the best hydrophobic properties. The test chamber experiments demonstrated that the deposition velocity of coated graphite flake decreased from 0.227 cm s⁻¹ to 0.187 cm s⁻¹ and its IR interference performance was improved, compared with uncoated graphite flake. The obtained results showed that the coatings on the graphite flake powder with hydrophobic nano‐silica enhanced the moisture resistance and electromagnetic interference performance of the graphite flake.     

Injection molding of glass flake reinforced polypropylene: Flake orientation and stiffness

Three samples of silane treated glass flakes of different diameters were dry blended with polypropylene powder and injection molded into rectangular (32 mm × 127 mm) plaques using an edge-gated mold cavity. The thicknesses of plaques were 1.6 mm, 3.2 mm, and 6.4 mm. Tensile and flexural specimens were machined from these plaques. Average flake diameters and thicknesses were determined. It was found that aspect ratios in finished moldings are quite similar, despite the initial (before processing) differences. The flake orientation varies across the thickness; it is parallel to the plane of the molding in the outer skin layer, changing gradually to perpendicular in the core. The relative thickness of the skin where the flake orientation is parallel increases with the decreasing thickness and flake concentration. It represents about 85% of the overall thickness in 1.6 mm moldings, between 70% and 85% when the plaque thickness is 3.2 mm, and between 50% and 60% in the thickest (6.4 mm) molding. Elastic properties can be interpreted using the modified rule of mixtures. Tensile moduli depends strongly on the flake orientation in the core and on the flake concentration, whereas the influence of the core on flexural moduli is insignificant. The flake orientation coefficients determined from micrographs are in good agreement with those calcuated from mechanical test. The coefficient accounting for finite flake aspect ratio, η_L was found to be about 0.3.     

An approach to the uniform dispersion of a high volume fraction of carbon nanotubes in aluminum powder

A slurry based process was developed to achieve the uniform dispersion of a high volume fraction of carbon nanotubes (CNTs) in aluminum powder. Al powder was subjected to surface modification to introduce a hydrophilic polyvinyl alcohol (PVA) membrane on its surface, which has good wettability and strong hydrogen bonding interactivity with functionalized CNTs. It was found that, when mixed with a CNT aqueous suspension, the PVA-modified Al (Al@PVA) powder resulted in much better adsorption uniformity of CNTs than the untreated Al powder. The adsorption capacity of CNTs was greatly enhanced by using nanoflake Al powder, which has better geometric compatibility with the CNTs and a larger surface area than spherical powder. Consequently, a uniform dispersion of 20 vol.% CNTs was achieved in the nanoflake Al@PVA powders. The advantage of this approach is that it provides easy control over adsorption uniformity and capacity of CNTs in a metal matrix, through the combination of surface modification and thickness adjustment of the metal flake powders.     

鳞片状富锌涂层耐蚀机理的研究

介绍了国外采用鳞片状锌粉取代球状锌粉研制富锌涂料发展的新趋势,对鳞片状锌基涂层抗蚀性能的机理进行了探讨,并从实际实验数据中得到了与理论分析相一致的结论,即鳞片状锌粉涂层在干膜含锌量降低的情况下,其抗蚀性能仍优于球状锌粉涂层,鳞片状富锌涂料是球状富锌涂料理想的换代产品。     

The properties of recycled PVC bottle compounds. 2: Reprocessing stability

Following a study of the mechanical properties of recycled PVC recovered from post-consumer bottles, this study focuses on the effects of recycled material on processing. In particular, the effects of multiple recycling were studied to investigate any problems that may arise due to the repeated incorporation of recycled material into the processing stream. Batches of recycled flake and powder as well as pure but processed bottle flake material were subjected to simulated multiple recycling using a Torque Rheometer. Ten minutes at 170°C followed by granulation represented one recycle. Molecular weight and Infrared analyses were performed to assess the degree of degradation occurring during reprocessing. The results indicated a rapid degradation of the two recycled grades when compared with the purer bottle flake PVC. Further multiple recycling was then performed on bottle flake mixed with 0.2% polyethylene, which showed that the PE impurities accelerate the degradation process. Finally, the effects of restabilizing by adding new bottle flake material at each step were investigated. It was shown that surprisingly small levels of new material (30%) prevented degradation, even after 15 recycle steps.     

磷石膏制备建筑石膏的实验研究

研究了磷石膏制备建筑石膏粉的工艺条件,通过添加减水剂改善磷建筑石膏粉的力学性能。采用常规分析方法、XRD和扫描电镜等方法对磷石膏原料,磷建筑石膏粉进行分析和表征。结果表明:磷石膏为片状结晶体,含有少量石英颗粒;在温度180℃和焙烧时间2.0 h条件下,半水石膏含量达到76.6%;磷建筑石膏粉强度随着减水剂掺量的增加而升高,聚羧酸减水剂掺量0.7%时,抗折强度达到15.0 MPa,强度提高近64.84%;FDN减水剂掺量0.7%时,抗折强度达到14.8 MPa,强度提高近62.64%。     

固化剂对环氧玻璃鳞片涂层性能的影响

以双酚A环氧树脂(E20)为主要成膜物,层片状玻璃鳞片和云母氧化铁为主要填料,辅助以铝粉、氧化铁红颜料,以及各种助剂和溶剂,再分别加入固化剂脂肪族胺加成物、聚酰胺TY-650,制得高固体分厚浆型环氧玻璃鳞片涂料。通过常规的力学性能(涂层的硬度、耐冲击性、柔韧性、附着力等)和耐腐蚀性测试,对比了不同固化剂对环氧玻璃鳞片涂层性能的影响。研究结果表明,脂肪族胺加成物与环氧树脂交联固化的玻璃鳞片涂层的硬度、附着力以及交流阻抗值都较高,具有良好的综合性能,加入铝粉对基体可起到阴极保护作用。     

不同溶剂对锌基涂层耐蚀性的影响

利用片状锌粉、铝粉、铬酐及其它有机物配制的锌基涂料具有良好的结合力和耐蚀性。探讨了不同溶剂对涂层的影响，涂层的耐蚀性以及其形貌结构。结果表明，所得涂层致密，耐蚀性比同厚度的锌镀层及镀锌钝化层要高得多。