NiFe2O4纳米冷冻机油对R134a饱和蒸气压的影响

利用稳态法,分别以R134a/冷冻机油、R134a/纳米冷冻机油为研究对象,对其饱和蒸气压进行实验研究.冷冻机油为SUNISO 3GS,在制冷剂/冷冻机油混合物中的质量分数分别为1%、3%和5%.纳米冷冻机油中纳米NiFe2O4的含量为3 g/L,实验温度范围为263～333 K.结果表明：当温度相同时纳米冷冻机油/R134a混合物的饱和蒸气压明显低于纯R134a,二者之间的差值随着含油量的增加而增大.     

纳米CuO冷冻机油对R134a饱和蒸气压的影响

采用稳态法,实验研究了纳米CuO冷冻机油对R134a制冷剂饱和蒸气压的影响.温度范围为:263～333 k;油浓度范围为:0～7wt%.结果表明:含有矿物纳米冷冻机油的R134a的饱和蒸气压低于相应的含矿物冷冻机油R134a或纯R134a的饱和蒸气压;矿物纳米冷冻机油对R134a饱和蒸气压的影响程度与相应的POE冷冻机油相当.实验结果佐证了纳米CuO粒子改善矿物冷冻机油和R134a的相溶性的假设.     

含有冷冻机油制冷剂的饱和蒸气压实验研究

采用稳态法测量了含油制冷剂的饱和蒸气压．基于Youbi方程,对分别含有矿物基冷冻机油SUNISO3GS和POE冷冻机油160SZPOE的R22和R134a制冷剂饱和蒸气压的实验结果进行了拟合．为了了解影响含油制冷剂饱和蒸气压的主要因素,比较了两种冷冻机油及其不同质量分数对制冷剂饱和蒸气压的影响．结果表明,冷冻机油的质量分数和温度是影响冷冻机油对制冷剂饱和蒸气压作用的重要因素．     

分散剂对Nano-TiO2矿物基冷冻机油分散稳定性的影响

在制冷工质替代工程中，研究纳米粒子在矿物基冷冻机油中的分散稳定性对于解决氢氟烃（HFC）类工质与矿物基冷冻机油之间的相溶性问题有非常重要的意义．通过3组实验，分析了分散剂对纳米TiO2矿物基冷冻机油分散稳定性的重要作用，并比较了不同种类、不同质量百分含量的分散剂对纳米TiO2矿物基冷冻机油分散稳定性的影响．实验结果表明：当纳米TiO2的质量百分含量为0．1％、选择0．5％～0．7％的Span-80作为分散剂时，制备出的纳米TiO2矿物基冷冻机油的分散稳定性较为理想．     

纳米铁酸镍粒子在SUNISO 3GS冷冻机油中的分散稳定性试验研究

纳米粒子在矿物冷冻机油中的分散稳定性是制备纳米冷冻机油的基础．通过沉降观测法,实验考察并确定了纳米铁酸镍粒子在SUNISO 3GS冷冻机油中分散方案,制备出相应的纳米冷冻机油．采用WFZ-26A型紫外可见分光光度计对所制备的纳米铁酸镍冷冻机油的稳定性进行了试验研究．结果表明：适量MH-95等分散剂对纳米铁酸镍粒子在SUNISO 3GS冷冻机油中的分散稳定性具有重要作用．     

超声波化学法制备尖晶石型纳米铁酸镍

在超声波辐射下用前驱体法合成纳米尖晶石型铁酸镍.对硝酸镍、硝酸铁以及脲的水溶液进行超声波辐射得到前驱体,在950°C下灼烧15 h得到粒径约为15 nm的NiFe2O4颗粒.用X射线衍射、透射电子显微镜以及红外光谱表征,结果表明,用超声波化学法合成的产物确为纳米铁酸镍.     

氟利昂R12及其替代物的分子构型和特征光谱研究

采用密度泛函理论对氟利昂R12及其替代物R134a在B3LYP/6-311G++(d,p)基组水平上进行结构优化和特征光谱计算.首次在该高精度基组下优化得到了R12和R134a的键长、键角和二面角等分子构型参数,且通过进一步的计算,得到了这两种分子的红外光谱和拉曼光谱.其中R12红外光谱的计算结果与美国国家标准局数据库(NIST)提供的实验结果基本吻合,说明了计算结果的准确性.另外通过从头算CIS方法对能量进行计算,得到了R12和R134a的紫外可见吸收光谱.计算结果可为进一步保护大气臭氧提供有用的数据参考.     

复合氧化物陶瓷在Na3AlF6—Al2O3熔体中的溶解性

用等温饱和法测定了NiFe2O4，ZnFe2O4，ZnAl2O4在Na3A1F6-A12O3熔体中的溶解度，研究了电解质温度、A12O3浓度和NaF与A1F3的分子比对NiFe2O4溶解度的影响．试验结果表明：NiFe2O4组元中Ni和Fe在熔盐中的饱和溶解度分别为0．0085％和0．0700％；ZnFe2O4组元中Zn和Fe的饱和溶解度别为0．0313％和0．0700％；ZnAl2O4组元中Zn的饱和溶解度为0．0265％；NiFe2O4在铝电解质熔盐中具有较强的抗腐蚀性能，是一种较好的金属陶瓷惰性阳极基体材料；NiFe2O4的溶解过程受离解及离解产物NiO与Fe2O3的化学溶解2个过程的控制，为提高NiFe2O4基陶瓷材料的耐腐蚀性能，宜采用低电解温度、低分子比和高氧化铝浓度等电解条件．     

纳米NiFe_2O_4磁性颗粒的制备及表征

以硝酸铁和硝酸镍为原料,尿素为沉淀剂,在水热温度180℃和水热时间12 h合成了纳米NiFe2O4磁性颗粒,并利用X射线衍射仪(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)和振动样品磁场计(VSM)等分析方法对样品进行了表征.结果表明:水热法所得纳米NiFe2O4颗粒为尖晶石结构,粒度分布均匀,粒径约为20 nm,具有明显的超顺磁性,饱和磁化强度为14.39 emu/g.     

可磁分离光催化剂的制备及其光催化性能研究

通过反胶束法和溶胶-凝胶法制备出了一种类蛋结构的可磁分离光催化剂纳米球ZnO@SiO2@NiFe2O4(ZSN),这种光催化剂显示出了超顺磁性和较好的光催化活性。该光催化剂的X-射线衍射和TEM分析结果表明:NiFe2O4纳米粒子被包裹在二氧化硅内形成磁性硅球SiO2@NiFe2O4(SN)载体,ZnO纳米粒子包覆在SN的表面,形成ZnO光催化壳层。光催化实验表明,在500℃下煅烧3h的ZSN表现出最佳的光催化活性。     

Interface chemical states of NiO/NiFe films and their effects on magnetic properties

Ta/NiOx/Ni81Fe19/Ta multilayers were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field ( Hex) and the coercivity ( Hc) of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied. The composition and chemical states at the interface region of NiOx/NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that the ratio of Ar to O2 has great effect on the nickel chemical states in NiOx film. When the ratio of Ar to O2 is equal to 7 and the argon sputtering pressure is 0.57 Pa, the x value is approximately 1 and the valence of nickel is + 2. At this point, NiOx is antiferromagnetic NiO and the corresponding Hex is the largest. As the ratio of Ar/O2 deviates from 7, the exchange coupling field ( Hex) will decrease due to the presence of magnetic impurities such as Ni +3 or metallic Ni at the interface region of NiOx/NiFe, while the coercivity ( Hc) will increase due to     

Effects of Nanoparticle Size and Morphology on IR Diffuse Reflection Spectra

1　IntroductionInfrared(IR)diffusereflectionspectroscopyisusedextensivelyintheanalysesandmeasurementsoforganicandinorganicsubstances ,especiallyforpowderma terials[1] .ButtheinfluenceofparticlesizeonIRspectraistypicallyconsideredasanuisancefactorwhichmanyscattercorrectionmethodsattempttoeliminate[2 ,3 ] .Insomereferences[4-6] ,ithasbeenalludedthattheparticlesizesweredeterminedbyIRdiffusereflectionspectra ,ap pliedtothetestingofpharmaceuticalproductsandrawmaterialswhoseparticlesizesarefromsev…     

Effects of hydrothermal temperatures on properties of magnetic titanate nanotubes

NiFe2O4 dopeded with magnetic titanate nanotubes(MTNT)were prepared by a hydrothermal method using magnetic nanoparticles TiO2/SiO2/NiFe2O4 as the precursor.The effects of hydrothermal temperatures on their composition,morphologies and magnetic properties of products were characterized by transmission electron microscopy(TEM),scanning electron microscopy(SEM),X-ray diffraction(XRD),vibration sample magnetometer(VSM)and energy dispersive X-ray spectroscopy(EDS).The results show that the hydrothermal temperature has a significant impact on the morphology of the products.The MTNT is synthesized in the temperature range of 120-160 ℃ and the inner diameter of MTNT is about 3-10 nm,the wall thickness 4-12nm and the length 100-200 nm.The components of MTNT are Na0.8H1.2Ti3O7 and a little of anatase TiO2 and NiFe2O4.The ferrimagnetisms and magnetic hysteresis phenomena are shown in the prepared MTNT.The hydrothermal temperature has no clear effect on the magnetic properties in the range of 120-180 ℃.The visible-light photo-catalytic activity of the products decreases as the temperature increases.The decolorization of methylene blue is 94.6% by the MTNT obtained at 120 ℃ and the recovery rate of MTNT is more than 95 percent.The MTNT has excellent photocatalytic activity and is easy to recovery.     

Effect of CaO doping on corrosion resistance of Cu/(NiFe_2O_4-10NiO) cermet inert anode for aluminum electrolysis

The CaO-doped Cu/(NiFe2O4-10NiO) cermet inert anodes were prepared by the cold isostatic pressing-sintering process, and their corrosion resistance to Na3AlF6-K3AlF6-Al2O3 melt was studied. The results show that the relative density of 5Cu/(NiFe2O4-10NiO) cermet sintered at 1 200 ℃ increases from 82.83% to 97.63% when 2% CaO (mass fraction) is added. During the electrolysis, the relative density of cermet inert anode descends owing to the chemical dissolution of additive CaO at ceramic grain boundary, which...     

Preparation and properties of 4.25Cu-0.75Ni/NiFe_2O_4 cermet

1INTRODUCTION NiFe2O4cermets,whichareexpectedtobe usedastheinertanodesforaluminumelectrolysis, havelowcorrosionandoxidation,goodelectricalconductivityandhighthermalshockresistance[15]. Nickelferritespinelformsacorrosion resistant networkthatcontainstheelectricallyconductivecopper basedmetallicphase.Especially,Gregget al[6]foundacermetofNiFe2O4 18%NiO 17%Cu (massfraction),whichshowedfavorablecorrosion andconductivitypropertiesasinertanodesinsmalllaboratorycells.However,itwasalsoshowedth…     

钨酸铁的超声合成及表征

利用乙二醇为表面活性剂,通过超声合成方法成功制备了粒径均匀、分散性良好的微米级FeWO4。利用粉末XRD、SEM及FT-IR等手段对所制备的FeWO4进行了表征。制得的FeWO4被固定在玻碳电极表面制成FeWO4/CHIT/GCE复合电极,电化学测试发现该电极能够加速Fe(Ⅲ)和Fe(Ⅱ)氧化还原对间的电子转移。进一步在该电极表面固定牛血红蛋白(Hb)后,即得到一种新型的可用于测定溶液中H2O2浓度的传感器。该传感器线性范围为5.0至460μmol·L-1,检测限为1.0μmol·L-1(3σ)。     

Preparation of high emissivity NiCr2O4 powders with a spinel structure by spray drying

Spray-drying was used to produce the high emissivity NiCr2O4 powders with a spinel structure. Preliminary investigations focused on fabricating the high emissivity powders for infrared radiation coatings and finding the relationship between microstructure and emissivity. The NiCr2O4 powders were characterized for composition, microstructure, and infrared emissivity by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared radiant instrument, and Fourier transform infrared spectra (FT-IR). Thermogravimetry and differential thermal analysis show that the appropriate baking temperature for NiCr2O4 powder preparation is about 1200?C. The emissivity measurement and FT-IR spectra show that, because of the special spinel structure, the NiCr2O4 powders have a high emissivity about 0.91. Spray-drying is a suitable method to produce the high emissivity ceramic powders.