固定污染源锡的测定石墨炉原子吸收法中涂锆对石墨炉灵敏度的影响研究

石墨炉测定固定污染源金属元素锡时,石墨管涂不涂锆对于仪器的灵敏度有很大的影响,涂锆将会提升石墨炉对于锡测定的灵敏度,不涂锆灵敏度将会大大折扣,甚至曲线都很难形成线性。从日常的分析测试中,通过对石墨炉测定锡元素涂锆的试验研究,先从曲线线性验证涂锆对灵敏度的提升,然后根据环境监测分析方法标准制修订技术导则HJ 168-2020中的要求,对涂锆后的石墨管进行固定污染源中锡的检出限、精密度和准确度验证。最后确定了涂锆石墨管具有灵敏度高、检出限低、精密度好、准确度高的特点,便于相关行业在使用石墨炉原子吸收测定固定污染源中锡时参考使用。

ELC石墨管涂锆-石墨炉原子吸收法在测定饮水中铝的应用

目的研究ELC石墨管涂锆的简易程序并用于石墨炉原子吸收测定饮水中铝的方法。方法采用每次进样20μl 4 g/L ZrOCl_2·8H_2O溶液,按仪器推荐的升温程序对ELC石墨管进行涂锆处理5次,再空烧5次即完成石墨管的涂锆处理。优化灰化、原子化温度等测试条件,在最优化测试条件下测试1%HNO_3空白溶液吸光度至低于0.005时正式开始测试。结果 ELC石墨管经涂锆处理,石墨炉原子吸收法测定饮水中铝,石墨管使用500余次未见性能显著下降(平行测定RSD<10%)。采用次灵敏线257.3 nm做测试波长,在0μg/L^200μg/L时线性关系良好,r>0.995。测定Al环境标准水样[GSB07-1375-2001,(150±15)μg/L],结果铝含量为135μg/L^163μg/L,均值为151μg/L,再现性精密度RSD为5.3%(n=16)。结论本法简便、快速、准确,可满足日常监测饮水中铝的测定。

石墨炉原子吸收分光光度法直接测定发样中铝

采用涂锆石墨管石墨炉原子吸收分析人发中的铝。其方法的特征量为 3.7× 1 0 -11g,检出限为 2 .52 ng· ml-1,相对标准偏差为 0 .9%～ 4.4%。

不同地区的大蒜和中草药等植物中锗含量的测定

采用涂锆石墨管石墨炉原子吸收光谱法 ,测定不同地区的大蒜和中草药等天然植物中锗的含量。结果表明 ,这些天然植物中锗含量在 1 0～ 30 0 0 ng/g之间。

原子吸收分光光度计测定地表水铝含量浅析

对地表水中铝含量的测定采用原子吸收法的两种方公式(即石墨炉原子吸收法和火焰原子吸收法)分别进行了试验,其中石墨炉原子吸收法测定中采用石墨管涂锆,基体改进剂为硝酸镁,准确度符合要求。火焰原子吸收法测定中采用空气-乙炔间接火焰原子吸收法,在调整了PAN用量下,标准曲线的相关系数r达到了0.9996,取得了良好的效果。

Influence of heat treatment on nanocrystalline zirconia powder and plasma-sprayed thermal barrier coatings

Nanostructured zirconia top coat was deposited by air plasma spray and NiCoCrAlTaY bond coat was deposited on Ni substrate by low pressure plasma spray.Nanostructured and conventional thermal barrier coatings were heat-treated at temperature varying from 1050 to 1 250oC for 2-20 h.The results show that obvious grain growth was found in both nanostructured and conventional thermal barrier coatings(TBCs)after high temperature heat treatment.Monoclinic/tetragonal phases were transformed into cubic phase in the agglomerated nano-powder after calcination.The cubic phase content increased with increasing calcination temperature.Calcination of the powder made the yttria distributed on the surface of the nanocrystalline particles dissolve in zirconia when grains grew.Different from the phase constituent of the as-sprayed conventional TBC which consisted of diffusionlesstransformed tetragonal,the as-sprayed nanostructured TBC consisted of cubic phase.

TBCs for Gas Turbines under Thermomechanical Loadings： Failure Behaviour and Life Prediction

The present contribution gives an overview about recent research on a TBC （thermal barrier coating） system consisted of （I） an intermetallic MCrAIY-alloy BC （bond coat） applied by VPS （vacuum plasma spraying） and （2） an YSZ （yttria stabilised zirconia） top coat APS （air plasma sprayed） at Forschungszentrum Juelich, Institute of Energy and Climate Research （IEK-2）. The influence of high temperature dwell time, maximum and minimum temperature on crack growth kinetics during thermal cycling of such plasma sprayed TBCs is investigated using scanning electron microscopy and AE （acoustic emission） analysis. Thermocyclic life in terms of accumulated time at maximum temperature decreases with increasing high temperature dwell time and increases with increasing minimum temperature. AE analysis proves that crack growth mainly occurs during cooling at temperatures below the ductile-to-brittle transition temperature of the BC. Superimposed mechanical load cycles accelerate delamination crack growth and, in case of sufficiently high mechanical loadings, result in premature fatigue failure of the substrate. A life prediction model based on TGO growth kinetics and a fracture mechanics approach has been developed which accounts for the influence of maximum and minimum temperature as well as of high temperature dwell time with good accuracy in an extremely wide parameter range.

A zirconium carbide coating on graphite prepared by reactive melt infiltration

A dense ZrC coating with the thickness of 130 μm is prepared on graphite by reactive melt infiltration.XRD and SEM analyses show that the phase composition of the coating is ZrC and it adheres well with the substrate.The influence of ZrC coating on mechanical properties of the graphite was investigated by compression tests and the results show that after the coating process,the compression strength of the coated sample is improved by 13.64% as compared with graphite sample.The improvement of the compression strength for ZrC coated sample can be associated to the increased density and the ZrC particle reinforcement due to the infiltration and reaction of the melted Zr with carbon substrate in the coating process.

Study and Characterization of Organically Modified Silica-Zirconia Anti-Graffiti Coatings Obtained by Sol-Gel

In this work, it is presented the synthesis and characterization of transparent and colorless organic-inorganic hybrid anti-graffiti protective materials obtained by sol-gel method. This type of materials is based on MTES （methyltriethoxysilane）, TPOZ （tetrapropoxide of zirconium） and PDMS （polydimethylsiloxane）. The synthesis has been carried out at 25, 35 and 45 ℃ in order to evaluate the role of temperature in the structure, microstructure and anti-graffiti behavior as well. The incorporation of zirconium within the organic modified silica network, of sols after being gelled and dried, is evident by a shoulder which increased with temperature situated at 950 cml （Si-O-Zr bonds）, and it is homogenously dispersed inside the matrix avoiding the formation of large ZrO2 precipitates. As the temperature increases, the hydrolysis and condensation reactions occur in more extension and thus, the obtained sols are more cross-linked and present more Si-O-Zr linkages. The promising anti-graffiti beha＇4ior of the protectNe hybrids was qualitatively determined being the spot removal higher than 90%.

Surface modification of ZrO_2 nanoparticles with styrene coupling agent and its effect on the corrosion behaviour of epoxy coating

The surface of ZrO2 nanoparticles was modified by styrene coupling grafting method to improve the dispersion and interaction of the nanoparticles with the epoxy coating in which the modified ZrO2 nanoparticles were used as an additive. The grafting performance and microstructure of the nano- ZrO2/epoxy coating were analyzed by Fourier transformation infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The corrosion behavior of the nano-ZrO2/epoxy coating on mild steel was evaluated in neutral 3.5 wt% NaC1 solution using electrochemical impedance spectroscopy （EIS）. Both the coating capacitance and coating resistance fitted by the equivalent circuit from EIS were used to evaluate the protective performance of the coating towards the mild steel. The results show a superior stability and efficient corrosion protection by the modified ZrO2 nanoparticles. The epoxy coating containing 2 wt% modified ZrO2 nanoparticles exhibited the best corrosion performance among all the coating specimens. This research may provide an insight into the protection of mild steel using modified epoxy coatings.

饮用水中铝的石墨炉原子吸收测定方法优化

探讨了采用石墨炉原子吸收法测定饮用水中铝含量时热解涂锆石墨管的制备方法和硝酸镁基体改进剂的用量，以及热解涂锆石墨管的原子吸收分光光度法的仪器工作条件。结果表明：热解涂锆石墨管比普通石墨管的使用寿命长；在0．0～100．0μg/L的测量范围内，当水样中硝酸镁含量为0．5％时，加标回收率为97．90％～100．4％。该方法检出限低、精密度高、稳定性好，可作为给水厂的水源水、过程水和出厂水中铝的检测方法。