用沸石吸收微波性能表征沸石特性的研究

研究了开放体系下微波加热沸石的规律,发现脱水的沸石能有效吸收微波,自身升温很快,如脱水NaA沸石400W功率下在100s内被加热到1473K.讨论了沸石晶体结构、硅铝比、可交换离子种类对沸石吸收微波的影响.不同类型的沸石,或同一类型但硅铝比不同的沸石,或不同离子交换的同一种沸石在同一功率下具有不同的升温速率,所能达到的最高温度也不尽相同,从而表明沸石吸收微波的性能有可能用来表征沸石的微观特性.沸石在不同功率下吸收微波性能不同,功率越大,升温越快.     

LSMO/SiO2复合材料变温微波吸收特性研究

通过固相反应法制备了LSMO/SiO2复合材料, 测试了LSMO材料500 MHz～18 GHz介电特性和LSMO/SiO2复合材料样品不同温度下X波段介电常数和微波吸收特性. 测试结果表明, 在12 GHz附近复合材料样品有明显的介电损耗特征峰, 随着温度的升高材料的介电常数虚部明显升高, tgδ变大;吸收特性测试表明, 随着温度升高, 吸收峰升高, 吸收峰略微往低频移动.     

微波消解-原子吸收法测定啤酒中的微量铝

利用微波消解-原子吸收法测定了啤酒中的微量铝。在密闭容器中采用微波、HNO3-H2O2消化制备试样溶液,然后在酸性介质中,铝与8-羟基喹啉生成1∶3络合物,通过甲基异丁基甲酮(MIBK)萃取,用氧化亚氮-乙炔火焰原子吸收法测定有机相中铝即可测定啤酒中微量铝。本法在0~500μg/L范围内呈良好的线性关系(R2=0.9991),可用于啤酒中微量铝的测定。     

二氧化硅改性片状铁粒子的微波吸收性能

The preparation and microwave-absorbing behavior of micrometric silica-modified platelet iron particles (SMPLIP) were investigated. Through precipitation， hydrothermal reaction， silica-modification and reduction with hydrogen， micrometric porous SMPLIP were yielded. The permittivity values of SMPLIP had been significantly decreased due to the presence of silica. Measurements and calculations showed that a 1.93mm thick sample containing SMPLIP as much as 60% by weight was capable of absorbing X band(8.2～12.4GHz) microwaves with reflection loss being greater than -10dB within the frequency range of 8.2～11.36GHz， while the maximum re-flection loss was -14.8dB at 9.4GHz. The results had also shown that it was practicable to prepare thin， light-weight microwave absorbent with SMPLIP.     

有机溶剂和二元体系溶液在9590兆赫的微波吸收分析应用

在９５９０兆赫和室温下，研究了一些有机溶剂和二元体系溶液的微波吸收。首次使用诱导效应指数来表达同系化合物的分子结构与其微波吸收之间的关系。研究了一些缔合和非缔合二元体系溶液的微波吸收，并提出了一个计算二元非缔合体系微波吸收的经验公式。此外，建立了利用微波测定白酒中乙醇含量的方法。     

钡铁氧体纳米复合材料的制备及其微波吸收性能

采用聚乙二醇(PEG)凝胶法制备了Ba(Zn1－xCox)2Fe16O27复合氧化物纳米材料，用X射线衍射分析对产物进行了表征.将制得的材料与传统的微波吸收剂铁粉结合起来，制成双层复合的吸波涂层，进行测试.实验结果表明，所制材料对微波具有良好的吸收性能.并进一步对纳米复合材料的吸波机理进行了探讨.     

吸收光度法中的峰位移

该文从吸收干扰、单色光性质及被测物吸收特性改变三个方面探讨了吸收光度法中吸收峰位移的原因、影响及其消除与应用。重点论述了吸收干扰中的相长与相消干扰引起的吸收峰位移规律。该规律为研究试剂与溶剂中杂质、样品中共存物、反应试剂与产物等的吸收干扰引起被测吸收峰位置、高度及形状的变化提供了理论依据。运用被测物标准溶液的正、负吸光度吸收曲线提供的信息与吸收峰位移规律研究吸收光度法应用的新方法,为定量分析、消除共存物干扰、化学反应及试剂选择性等研究提供了新手段。作为峰的相长与相消干扰引起的测定峰位移规律也适用于检测峰的其它仪器分析。     

微波法快速清洗冷原子吸收测汞法所用玻璃仪器

冷原子吸收测汞法因所用玻璃仪器对汞的吸附力很强,利用传统方法处理后,空白值吸光度多在0.07以上,甚至高达1.05,无法继续使用.本文将高锰酸钾-硝酸-硫酸煮沸法与微波加热技术结合起来处理玻璃仪器,加速汞从玻璃表面的洗脱.试验表明,该法快速简便,洗涤效果好,结果令人满意.     

微波加压溶样冷原子吸收法测定氟石粉中微量汞

本文采用美国CEM公司生产的MDS-2000型微波样品制备系统分解氟石粉样品,然后用冷原子吸收法测定氟石粉中微量汞,测定下限达0.01μg·g~(-1).一般出口合同中常规定氟石粉中含汞量小于0.3μg·g~(-1),为此采用本法完全能满足合同检验要求.微波制样系统是将微波加热技术与高压密闭溶样结合为一体,采用微处理机控制溶样过程的温度与压力.密闭容器微波消解样品,利用在2～3min内获得高温、高压分解样品,具有快速不易挥发损失等优点.     

微波消化,原子吸收法测定益健露中铅

采用微波溶样技术消解样品，用原子吸收法测定了益健露中铅含量。     

微波消解-火焰原子吸收法测定土壤中的钴

建立了微波消解一火焰原子吸收法测定土壤中钴的方法：用微波消解土壤、电热板加热驱酸的方法对土壤样品进行前处理,优化了微波消解条件。方法的加标回收率为93．0％～106．0％,检出限为3．0μg/g,测定结果的相对标准偏差为2．1％～4．9％（n=6）。     

La0.6Ce0.4Mn1-yFeyO3微波吸收特性

用溶胶-凝胶法制备了La0.6Ce0.4Mn1-yFeyO3 (y=0.00, 0.12, 0.14, 0.16, 0.18)样品. 用微波矢量网络分析仪测试了该样品在2～18 GHz微波频率范围的复介电常数、复磁导率, 根据测量数据计算了电磁损耗角正切及微波反射率与频率的关系. 结果表明, 当B位掺入铁元素时, 样品吸收峰值增大, 有效吸收频带增宽, 在y=0.14时, 样品微波吸收效果最好. 当样品厚度为2.00 mm, y=0.14时, 吸收峰值为38 dB, 10 dB以上频带宽度达4.1 GHz. 初步探讨了该材料的电磁损耗机理, 发现损耗吸收来自磁损耗和介电损耗的共同作用, 吸收峰所在频率介于介电损耗角正切最大值与磁损耗角正切最大值对应的频率之间, 即在12.7 GHz附近. 对样品的电阻率测试表明, 其室温范围内电导在半导体范围内, 有利于降低微波在样品表面的反射率.     

多晶铁纤维的合成与微波吸收性能的研究

The preparation and microwave-absorbing behavior of polycrystalline iron fibers modified with the thermal decomposition of carbonyl iron were studied in this paper. Through preparation of α-FeOOH fiber precursor, dehydration, reduction with hydrogen, modification with the thermal decomposition of carbonyl iron and passivation, polycrystalline iron fibers were yielded. α-FeOOH fiber precusor with optimum diameter and aspect ratio was made by using uniform seed crystal with optimum concentration and controlling the reaction time. Lacunas from procedure of dehydration and reduction were well modified with carbonyl iron. The sample with 1.95 mm thickness containting 60 % by weight of modified polycrystalline iron fibers showed reflection loss over 10 dB within the frequency range of 8.5～14.6 GHz, and the maximum reflection loss was 21.8 dB at 11.3GHz, while the sample of nonmodified polycrystalline iron fiber showed less reflection loss under same conditions.     

利用煤矸石制备负载Fe3O4的陶瓷复合材料及微波吸收性能研究

本研究以固废煤矸石为主要原料,通过对其进行破碎、球磨、酸洗处理、造粒成球和煅烧得到煤矸石载体,经液相负载与原位碳热还原制得Fe3O4负载的陶瓷复合微波吸收材料,并且研究了Fe3O4负载量对复合材料结构及电磁性能的影响规律.结果表明,当焙烧温度为600?℃、前驱体溶液浓度为1.25?1.5?mol/L时,复合材料的微波吸...     

微波消解-石墨炉原子吸收法测定食品中的砷

微波消解,采用硝酸镍氯化钯作为基体改进剂石墨炉原子吸收法测定食品中的砷。结果表明,与现行国标中的测砷的方法比较没有显著性差别。具有快速、简便、准确的特点,而且灵敏度高,能满足食品中砷的卫生标准要求。     

微波消解-火焰原子吸收法测定猪肝脏中的铅

采用微波消解—火焰原子吸收法对猪肝脏(鲜)中的痕量铅进行了测定,建立了一种微波消解样品、火焰原子吸收法测定猪肝脏(鲜)中痕量铅含量的方法.研究结果表明,在取样量为0.8g左右、HNO3(65％)∶H2O2(30％)=1∶1(体积比)、中等微波功率消解3 min的条件下,检测到猪肝脏中铅的含量为0.173 μ g/g.该...     

中空纤维致密膜基吸收CO2传质过程

研究了硅橡胶/聚砜中空纤维致密膜基吸收CO2的传质机理,考察了吸收剂种类(NaOH,MEA,DEA和TEA)、NaOH浓度、吸收剂流速、吸收剂压力和气相压力对CO2传质通量及传质速率的影响.其中,用2×103mol/m3NaOH作吸收剂时,聚合物膜传质为控制步骤,其传质效率与膜自然渗透相近.     

微波活性炭形成高比电容量的微结构机理

1引言 活性炭的制备目前通常采用常规加热进行，存在能耗大、环境污染严重、用作超级电容器电极的性能待提高等问题。微波加热是一种新的加热方法，它与常规加热方式不同，物体的升温不是通过热传输而是通过外场与物体相互作用完成的。微波加热具有选择性、整体性、均匀性、可快速启动与停止、节能无污染等优点，因此以微波作为加热方式制备活性炭的研究引起了人们的兴趣。     

基于核壳结构Co3Fe7@C的高效微波吸收材料

To reduce the density of the absorbent Co₃Fe₇, a core-shell Co₃Fe₇@C microwave absorbent was synthesized by preparing an iron/cobalt-containing carbon precursor followed by high-temperature carbonization. According to the X-ray diffraction (XRD) and transmission electron microscopy (TEM) results, Co₃Fe₇ particles were coated with graphitized carbon layers to form a core-shell structure. Furthermore, the Co₃Fe₇@C composite with a surface area and density of 358.5 m²·g^-1 and 2.25 g·cm^-3, respectively, exhibited excellent microwave absorbability. A minimum reflection loss (RL) of -43.5 dB and an effective bandwidth (RL below -10 dB) of 4.1 GHz were obtained at the coating thickness of 2 mm, which could be mainly attributed to the effective impedance match and multiple interfacial polarizations. Owing to the low density and remarkable microwave absorption, we believe that the Co₃Fe₇@C composite can be a promising candidate for use as a lightweight and efficient microwave absorbent.     

替代M-型钡铁氧体纳米粒子的微波吸收性能

The microwave-absorbing behavior of substituted M-type barium ferrite nano-particles was investigated. The nano-particles were synthesized with coprecipitation-melted salt method. For the purpose of comparison, corre-sponding micro-particles were also prepared through direct coprecipitation and sintering. XRD and TEM of the nano-particles showed that the ferrite was hexagonal in structure and widely distributed in size with particle size being less than 100nm, the complex permittivity and permeability of a 1.50mm thick specimen and a 1.40mm thick specimen containing 60% by weight of substituted M-type barium ferrite nano-particles and micro-particles were measured respectively in X band (8.2～12.4GHz) range, from which the reflection loss (R.L.) of microwaves was calculated and two comparative absorption curves were given. The results showed that the synthetic nano-particles could well absorb microwaves in X band. The absorption was larger than 10dB in the range of 9.2～12.4GHz while the maximum absorption was 38.6dB at 10.6GHz.