Cu2+掺杂调控NiZn铁氧体的P波段吸波性能

目的 研究离子掺杂对NiZn铁氧体电磁特性的影响,提高NiZn铁氧体的P波段吸波性能。方法 以NiO、ZnO、Fe2O3、CuO等为原料,采用高温固相反应法,通过球磨、预烧、造粒以及烧结等工艺,制备Cu²⁺掺杂的Ni0.22Zn0.66CuxMn0.04Co0.08–xFe2O4(x=0.04、0.05、0.06、0.07)铁氧体样品。通过XRD、VSM和SEM分别表征样品的晶格特征、磁学特性和微观形貌,利用阻抗分析仪对样品的电磁特性进行测量。结果 Cu²⁺掺杂量的增加引起NiZn铁氧体的A-B超交换作用减弱和磁晶各向异性降低,样品的Ms、Hc和Mr都呈现出减小的趋势。样品的复磁导率与其磁特性关系密切,随着Cu²⁺的增加,实部μ?减小,而虚部μ?增大。此外,Cu²⁺掺杂量的增加对Fe²⁺与Fe³⁺之间的电子迁移率产生影响,使得复介电常数实部ε?增大,而ε?增大的主要原因是Cu²⁺掺杂量的增加导致铁氧体内部产生了晶格缺陷。Cu²⁺的掺杂量对样品的P波段吸波性能影响显著,随着Cu²⁺掺杂量的增加,NiZn铁氧体的阻抗匹配特性明显改善,电磁衰减能力显著提高,这进一步降低了样品的最佳吸波匹配厚度。掺杂量x=0.07的NiZn铁氧体样品,在厚度为6.6 mm时,实现了有效吸波带宽完全覆盖P波段。结论 通过调节Cu²⁺的掺杂量可以调控NiZn铁氧体的P波段吸波性能,增加Cu²⁺掺杂量对于降低样品的P波段吸波匹配厚度有积极作用。     

一种新的油田产出水中咪唑啉类缓蚀剂残余浓度的检测方法

分析了紫外分光光度法测定咪唑啉类缓蚀剂浓度的局限性,找到了一种使用新型显色剂就能对油田产出水中咪唑啉类缓蚀剂残余浓度的简单而快速的检测方法,该方法检测速度快、误差小、可抗原油干扰。     

基于基团贡献法估算(富锂)锂离子电池正极材料Li1+ xM 1- x O2 的热力学性质

富锂Li_1+xM_1-xO₂材料的研究主要集中在其结构和电化学性能上,而很少关注其热力学性能。开发具有高能量密度和容量的新型富锂材料取决于这种材料的结构、热力学性质和电化学性质之间的固有关系。对富锂材料Li_1+xM_1-xO₂的热力学性质了解不足,使得新型Li_1+xM_1-xO₂材料的开发和利用受到限制。鉴于Li_1+xM_1-xO₂材料缺乏热力学数据,根据基团贡献方法的原理对LiAlO₂进行拆分。基于热力学原理,提出了用于估计LiAlO₂的ΔG^θ_f,298、ΔH^θ_f,298和C_p的数学模型。采用基团贡献法估算了56种固体无机化合物的ΔG^θ_f,298和ΔH^θ_f,298以及54种固体无机化合物的C_p,298,以检验该模型的可靠性和适用性。利用基团贡献法估算了固体无机化合物的数学模型。利用基团贡献法拟合的基团参数选择的实验数据准确可靠。在结果令人满意的基础上,建立了用于估算3种类型的Li_1+xM_1-xO₂材料的ΔG^θ_f,298,ΔH^θ_f,298和C_p的数学模型,并估算了63种常见Li_1+xM_1-xO₂材料的ΔG^θ_f,298、ΔH^θ_f,298和C_p,298。     

18CrNiMo7-6渗碳钢相变塑性系数对残余应力的影响

目的 研究碳含量对相变塑性系数的影响,并精确仿真18CrNiMo7-6钢渗碳淬火后的残余应力分布。方法 制备四种不同碳含量(0.21%、0.49%、0.65%、0.87%)的全渗透试样,分别进行不同应力水平下的膨胀试验,测得不同碳含量试样的相变塑性系数K,并输入DEFORM-HT中进行残余应力仿真,同时对 16.72 mm的圆柱试样进行渗碳淬火试验,以验证残余应力模拟的准确性。结果 前三种碳含量下马氏体相变动力学参数α变化不大。基于此,提供了一种便于计算高碳含量试样不完整膨胀曲线的K值的方法,计算四种不同碳含量试样的相变塑性系数分别为7.16×10^–5、5.45×10^–5、5.53×10^–5、6.01×10^–5 MPa^–1。分别采用不考虑相变塑性即K=0 MPa^–1、取为基体值即K=7.16×10^–5 MPa^–1和试验测得与碳含量相关的相变塑性系数进行残余应力仿真,其中采用试验测得相变塑性系数仿真结果与实测的残余应力吻合度最高,残余压应力从表面到心部呈现先增大后减小的趋势。结论 经渗碳淬火后的试样表层存在碳梯度,不同碳含量下影响相变塑性系数数值的主导机制不同,导致相变塑性系数随着碳含量的增加而先降低后升高,且其对18CrNiMo7-6钢渗碳淬火后残余应力分布的影响显著。     

A3钢在富营养化东湖水中初期腐蚀研究

    以A3钢为研究对象,采用失重实验和电化学技术研究了A3钢在富营养化东湖水中的腐蚀行为.结果表明：A3钢在实验过程中腐蚀电流随时间增长逐渐减小;自腐蚀电位先降后升,而极化电阻逐渐增大,说明电极表面刚开始处于活化状态,然后电极表面“保护膜”不断生长,将电极表面覆盖,减缓了基体的腐蚀;电化学方法计算出富营养化水中A3钢的腐蚀电流与线性极化电阻的比例常数B值为23.6242;通过XPS分析得出A3钢腐蚀产物的成分为FeOOH,Fe³⁺与C、N、S结合的有机产物和FeSO₄,其中Fe²⁺/Fe³⁺=0.24.     

CO2和SRB共存产出水中咪唑啉衍生物的环境行为及缓蚀长效性研究

采用腐蚀失重法、三维显微镜和电化学方法研究咪唑啉在含有硫酸盐还原菌(SRB)的饱和CO2模拟水中的缓蚀行为,通过紫外分光光度法同步检测咪唑啉浓度变化,研究咪唑啉对SRB生长影响及通过Fourier红外分析咪唑啉残余物质结构。结果表明,缓蚀剂的添加抑制了SRB的生长,经过10 d的培养后,在有/无SRB的体系中缓蚀剂都具有很高的缓蚀性能,缓蚀率分别为93.0%和94.4%。在有/无SRB体系中的咪唑啉含量分别减小为86.5%和87.5%,红外分析表明残余物质含有咪唑啉的五元环结构特征峰,咪唑啉缓蚀剂不会因SRB生长而使特征官能团断开,其缓蚀性能具有长效性。     

Cl–浓度对阳极氧化5A06铝合金/1Cr18Ni9Ti不锈钢偶接件腐蚀行为的影响

目的 研究阳极氧化铝合金/1Cr18Ni9Ti不锈钢偶接的电偶腐蚀机理及Cl^–浓度对其腐蚀行为的影响规律,为铝合金在不同服役环境中的腐蚀与防护提供依据。方法 通过电偶腐蚀实验,在不同Cl^–浓度下偶接阳极氧化5A06铝合金和1Cr18Ni9Ti不锈钢,根据腐蚀电流的变化规律分析、表面腐蚀形貌与成分的表征、并结合电化学测试,分析了Cl^–浓度对阳极氧化5A06铝合金的电偶腐蚀行为的影响。结果 随着腐蚀时间的延长,电偶电流呈现锯齿状波动,总体表现为由高到低逐渐趋于稳定。电偶电流随着Cl^–质量分数的变化表现为3.5%>5%>2%>6.5%>8%>0.5%,且当Cl^–质量分数为3.5%时电偶电流最大为16.56 μA/cm²。结论 电偶腐蚀过程中5A06铝合金阳极氧化膜表面的腐蚀产物对点蚀坑产生堵塞,阻碍了溶液中Cl^–进一步和基体发生反应,阳极氧化膜表现为破坏—修复—破坏的循环往复过程;溶液中Cl^–既可以促进铝合金阳极氧化膜的溶解,增加铝合金电偶腐蚀的敏感性,也会降低溶液中溶解氧的浓度从而抑制阳极反应发生。当Cl^–质量分数<3.5%时其促进溶解作用大于抑制反应作用,而当Cl^–质量分数>3.5%时其抑制反应作用大于促进溶解作用,因此电偶腐蚀速率随着Cl^–浓度的增大呈现先增大后减小的规律。     

喷丸处理对45钢表面Al+注入层抗高温氧化性的影响

为改善45钢的抗高温氧化性能，在其表面制备单一Al⁺注入层和喷丸+Al⁺注入层。检测表征改性层的表面粗糙度、显微硬度、微观形貌、以及铝元素含量，并进行600℃、200 h下的抗高温氧化性能试验。研究结果表明：喷丸处理45钢表面呈现出凹坑、丘陵状、具有近似等轴状纳米晶结构，Al⁺注入使纳米晶进一步细化。喷丸处理使45钢的表面粗糙度Ra从0.42 μm增至1.15 μm，显微硬度、注入铝元素含量及氧化增重分别从单一Al⁺注入层的257 HV_0.05增至喷丸+Al⁺注入层的最高505 HV_0.05，从3.7%增至4.2%和从14.8 mg·cm^-2降至8.3 mg·cm^-2。即喷丸处理有效增强了45钢表面Al⁺注入层的抗高温氧化性能。     

油气田产出液缓蚀剂残余浓度在线监测技术及应用

介绍了一种油气田缓蚀剂浓度现场检测方法和移动式在线分析仪,该分析仪采用紫外(UV)光谱和显色剂技术测量油田产出液中缓蚀剂的残余浓度。仪器以长寿命脉冲氙灯作光源,单色器为衍射光栅后分光,通过光栅将紫外光导入到流动比色池中,透射光再通过光纤导入光电二极管阵列(PDA)。分析仪在微处理器控制下,可以对油田产出液进行快速UV光谱扫描和残余缓蚀剂浓度测量。为防止污水中的残余油污污染流动比色池,监测仪前端采用过滤柱进行初步油水分离,分离后流体由蠕动泵自动压入流动比色池进行UV光谱分析,通过先期建立的吸光度-浓度标准曲线,再由流水的吸光度计算水中的缓蚀剂残余浓度。     

晶界添加Ho63.3Fe36.7 对NdFeB再生磁体组织与性能的影响

采用一种高效、绿色的物理方法对NdFeB废旧磁体表面进行清理并回收利用。通过晶界添加低熔点Ho_63.3Fe_36.7合金制备NdFeB再生磁体。在未添加Ho_63.3Fe_36.7的磁体中,没有足够的富Nd相隔离Nd₂Fe₁₄B相,从而导致磁体性能较差;随着Ho_63.3Fe_36.7合金的加入,晶界相变得清晰且连续。在质量分数2%Ho_63.3Fe_36.7添加量下,钕铁硼再生磁体获得最佳磁性能[(BH)_max+H_cj=1756.07]。此时矫顽力增加123 kA/m（约提高9.1%）,磁体的最大能积由290.94 kJ/m³下降到281.07 kJ/m³,而剩磁少量下降。通过对再生磁体显微组织和成分的分析可知,磁体晶界处形成了(Nd, Pr, Ho)₂Fe₁₄B壳层,这能够提高磁体的矫顽力。而X射线衍射分析表明,磁体I₍₀₀₆₎/I₍₁₀₅₎的衍射峰强度比从0.92提高到1.32。这说明磁体取向度提高,可以减弱对剩磁的影响,从而使得再生磁体在保持剩磁的同时提高磁体的矫顽力。     

Photoluminescence properties and energy-transfer of thermal-stable Ce, Mn-codoped barium strontium lithium silicate red phosphors

A series of thermal-stable Ce³⁺, Mn²⁺-codoped barium strontium lithium silicate (BSLS) phosphors was synthesized by a high-temperature solid-state reaction. The XRD patterns of this phosphor seem to be a new phase that has not been reported before. BSLS:Ce³⁺, Mn²⁺ showed two emission bands under 365 nm excitation: one observed at 421 nm was attributed to Ce³⁺ emission, and the other found in red region was assigned to Mn²⁺ emission through Ce³⁺-Mn²⁺ efficient energy transfer. The Mn²⁺ emission shifted red along with the replacement of barium by strontium, which was due to the change of crystal field. A composition-optimized phosphor, BSLS:0.10Ce³⁺, 0.05Mn²⁺ (Ba = 65), exhibited strong and broad red-emitting and supreme thermal stability. The results suggest that this phosphor is suitable as a red component for NUV LED or high pressure Hg vapor (HPMV) lamp.     

Nanocrystallization and photoluminescence of Ce/Dy/Eu-doped fluorosilicate glass ceramics

Ce³⁺-Eu²⁺-Dy³⁺-Eu³⁺-doped fluorosilicate glass ceramics containing orthorhombic CaCeOF₃ nanocrystals were prepared by annealing the precursor glass above 640 °C, along with the reduction of Eu³⁺ → Eu²⁺. Under near ultraviolet excitation, the emission bands of Eu²⁺ or Dy³⁺ were enhanced by several ten or hundred times, owing to energy transfers from Ce³⁺ to Eu²⁺ or Dy³⁺. The glass and glass ceramics emitted warm white light deriving from the blue, yellow and red emission from Eu²⁺, Dy³⁺ and Eu³⁺. Tuning the annealing temperature, the Eu²⁺/Eu³⁺ ratio and the warm white Commission Internationale de I’Eclairage (CIE) coordinates can be adjusted. Thus, the present materials can be applied on warm white high power light-emitting-diodes for indoor illumination application.     

Upconversion luminescence of Yb/Tb/Er-doped fluorosilicate glass ceramics containing SrF2 nanocrystals

Yb³⁺/Tb³⁺/Er³⁺-doped transparent alkaline earth fluorosilicate glass ceramics containing SrF₂ nanocrystals were prepared and their microstructures and spectroscopic properties were investigated. The formation of SrF₂ nanocrystals enriched with Yb³⁺/Tb³⁺/Er³⁺ in the glass ceramics was confirmed by XRD, HRTEM and SAED. The glass ceramics exhibited intense upconversion luminescence behaviors, owing to efficient energy transfers from Yb³⁺ to Er³⁺ and Tb³⁺ and low phonon assistant non-radiative transition probabilities of excited Er³⁺ and Tb³⁺. The upconversion could be enhanced significantly by increasing the annealing temperature and the luminescence color could be adjusted by varying the Yb³⁺/Tb³⁺/Er³⁺ ratio. Upconversion of Er³⁺ could be described as sequential energy transfer from single Yb³⁺ to single Er³⁺, while upconversion of Tb³⁺ described as cooperative energy transfer from double Yb³⁺ to single Tb³⁺.     

Substrate Effect on the High-Temperature Oxidation Behavior of a Pt-Modified Aluminide Coating. Part I: Influence of the Initial Chemical Composition of the Coating Surface

The effect of substrate composition on the oxidation behavior of the industrial NiPtAl coating RT22 ^TM was investigated by studying the isothermal and cyclic-oxidation behavior of this coating deposited on three different Ni-base superalloys (CMSX-4 ^TM , SCB ^TM and IN792 ^TM ). Isothermal tests were performed at 900, 1050 and 1150°C for 100 h. Cyclic oxidation was studied at 900°C with a holding time of 300 h for up to 52 cycles (i.e, 15,600 h at 900°C). Thermogravimetric analysis (TGA), X-ray diffraction (XRD), microstructural and analytical investigations using scanning-electron microscopy (SEM) and transmission-electron microscopy (TEM), both equipped with energy-dispersive X-ray spectroscopy (EDS) were performed to characterize the oxidation behavior of the systems studied. An effect of the superalloy substrate was observed and related to the initial chemical composition of the coating surface which depends on the superalloy and the associated heat treatments. The effect of the substrate’s alloying elements is discussed. Particularly the influence of Ti and Ta that formed rutile-type oxides inducing oxide-scale cracking and spallation. The excellent resistance to cyclic oxidation of the coating systems studied at 900°C was also demonstrated from very long duration tests of 15,600 h.     

Cl-浓度对含盐污水中 10#碳钢腐蚀行为的影响

针对兰州石化某常减压装置换热器管束(主要材质为10#碳钢)在使用过程中发生腐蚀的问题,通过浸泡试验和电化学测试,研究了壳程介质中的Cl-浓度对10#碳钢在含盐污水中腐蚀行为的影响。结果表明:弱碱性溶液中的OH-与Cl-竞争吸附,使得Cl-浓度的变化对碳钢的腐蚀速率基本没有影响,其腐蚀速率在0.145～0.185 mm/a之间。     

Impact of Ce ion on microstructure and luminescence character of Ho/Yb co-doped ZrO2 nanocrystal

By solid-state synthesis method, Ho³⁺/Yb³⁺ co-doped CeO₂-ZrO₂ nano-powders have been prepared. The concentration of Ce⁴⁺ ions has greater effect to the oxygen lattice structure. When the concentration of Ce⁴⁺ ions is 30 mol%, the oxygen lattice is a tetrahedral space group and the luminescence intensity of the sample is strongest. The results show that the lattice structure can be changed by inducting the Ce⁴⁺ ions into Ho³⁺/Yb³⁺ co-doped ZrO₂. And the emission character can be improved.     

Luminescence properties of Eu and Eu doped calcium-deficient hydroxyapatite prepared in air

Eu-doped calcium-deficient hydroxyapatite Ca_8.95Eu_0.05HPO₄(PO₄)₅OH (designated CDHA:Eu) was prepared via the coprecipitation method and calcined in air. Phase purity, crystal structure and morphology of the CDHA:Eu were characterized using X-ray diffraction spectrometer and scanning electron microscopy. The photoluminescence excitation and emission spectra of Eu²⁺ and Eu³⁺ ions were measured using luminescence spectrometer. The emission spectra showed a broad emission band centered at 450 nm corresponded to the typical 4f⁶5d¹ → 4f⁷ transition of Eu²⁺ ions, and sharp peaks corresponded to the ⁵D₀ → ⁷F_J (J = 0, 1, 2, 3, 4) transitions of Eu³⁺ ions. This research was focused on the site-distribution of Eu³⁺ ions. The Eu³⁺ in different sites had different spectroscopic features and the charge compensation mechanisms were also discussed.     

Upconversion luminescence properties of Tm-Yb co-doped titania-zirconia composites nanocrystals

Tm³⁺-Yb³⁺ co-doped titania-zirconia composites were synthesized by co-precipitation method with aqueous ammonia as precipitator. Time evolution of upconverted emission of thulium in ZT_0.4-Tm_0.01Yb_0.04 (40%ZrO₂-60%TiO₂-1%Tm³⁺-4%Yb³⁺) demonstrated ZT_0.4 to be a promising matrix in the field of upconversion luminescence. Raman spectrum shows low phonon energy (800 cm⁻¹) of ZT_0.4 ensuring a fluent phonon transition process. The luminescent properties were investigated by photoluminescence spectra. Strong blue and red upconversion emissions could be observed which were attributed to ¹G₄-³H₆, ³F₂-³H₆, ¹G₄-³F₄ transitions, respectively.     

Photoluminescent properties of LiSrxBa1−xPO4:RE (RE = Sm, Eu) f-f transition phosphors

Rare-earth ions (Sm³⁺ or Eu³⁺) doped LiSr_xBa_1−xPO₄ (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) f-f transition phosphor powders were prepared by a high temperature solid-state reaction. The resulted phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. The results of XRD indicate that the phase structure of the sample changes from LiBaPO₄ to LiSrPO₄ when x changes from 0 to 1.0. The excitation spectra indicate that only direct excitation of rare earth ions (Sm³⁺ or Eu³⁺) can be observed. The doped rare earth ions show their characteristic emission in LiSr_xBa_1−xPO₄, i.e., Eu³⁺⁵D₀-⁷F_J (J = 0, 1, 2, 3, 4), Sm³⁺⁴G_5/2 → ⁶H_J (J = 5/2, 7/2, 9/2, 11/2), respectively. The dependence of the emission intensities of the LiSr_xBa_1−xPO₄:Sm³⁺ and LiSr_xBa_1−xPO₄:Eu³⁺ phosphors on the x value and Ln³⁺ (Ln³⁺ = Sm³⁺, Eu³⁺) concentration is also investigated.     

Investigation on temperature dependence of photoluminescence in Sr1.7Eu0.3MxCeO4.15+x/2 (M = Li, Na, K, x = 0, 0.3) red phosphors

The temperature-dependent luminescence of Sr_1.7Eu_0.3M_xCeO_4.15+x/2 (M = Li⁺, Na⁺, K⁺, x = 0, 0.3) samples was investigated and discussed in the temperature range from 303 to 573 K. It is found that the thermal quenching temperature of samples decreases with Li⁺-/Na⁺-doping but increases with the incorporation of K⁺. We suggest that these observations are resulted from two factors. One is that the incorporation of Li⁺/Na⁺/K⁺ ions reduces the strength of potential field at the O²⁻ sites, and then results in a red-shift of the Eu-O charge transfer band. The other is that Δr expands with Li⁺-/Na⁺-doping but shrinks with K⁺-doping. We consider that it is a feasible way to adjust the temperature-dependent luminescence properties of materials by introducing appropriate impurities.