基于辐射加热源的材料高温发射率测量方法

材料高温辐射特性参数是量化研究热输运过程中的基本参数。本文将高能流太阳能聚集模拟器引入到材料高温发射率测量中,利用高能流太阳能聚集模拟器产生的可见光及近红外光谱辐射直接对样品进行加热,建立了材料中红外波段的高温发射率测量方法,避免了常规测量中封装窗口及高温炉体自身光谱辐射对测量的影响。基于该方法,采用红外热像仪、FTIR光谱仪等设备,搭建了实验平台,理论上可实现1700 K以内的样品发射率测量。采用该装置对某型钢进行了实验测量,获得了材料7~25μm波段内不同温度下的发射率曲线。     

固态离子晶体β-K0.294Ga1.969O3的高压与变温拉曼光谱研究

β-镓酸盐（β-gallate）型化合物是一种非常有应用前景的固态离子导体,在储能领域具有重要的应用价值。该类型化合物导电层中往往可以容纳过量的碱金属离子,使得该体系体现出复杂的晶格动力学行为,这也为进一步理解其导电机制带来了困难。压力与温度两个参量均可以通过改变原子间的间距而影响材料的结构,在研究材料的动力学过程,尤其在研究离子的扩散过程方面有很大的应用价值。迄今为止,对于温度依赖的β-镓酸盐型化合物的特性研究很少,且尚无β-镓酸盐型结构化合物的高压研究。由于激光拉曼散射技术在研究物质晶格动力学方面的独特优势,尤其压力与温度依赖的拉曼光谱可以提供重要的结构信息,是研究物质晶格动力学行为的有效实验手段。使用大腔体静高压技术成功合成了一种新型的β-镓酸盐型K_0.294Ga_1.969O₃(KGO)晶体,利用扫描电镜、能谱对晶体进行了表征,通过单晶X射线衍射对其晶体结构进行了解析,并与β-Ga₂O₃的晶体结构进行了对比分析。利用高压和变温拉曼光谱研究了KGO导电层中无序碱金属离子的晶格动力学行为。研究发现,由尖晶石层与疏松的离子导电层交替排列而成的β-镓酸盐型KGO晶体结构在压力23.3 GPa条件下仍可保持稳定;由于振动模式不同,高频拉曼模与低频拉曼模的压力系数存在着显著差异,并表现出显著的对压力诱导非谐性。在约300 ℃,KGO中K+发生热激活,表现在与碱金属K+运动相关的低频拉曼模的强度迅速增加,而与Ga-O多面体相关的高频振动模强度增加缓慢,与此同时,K+在沿着导电平面的方向上发生了无序扩散过程。研究结果将有助于深入地理解β-镓酸盐型结构化合物的导电机制,而且对于实现β-镓酸盐型化合物精确的计算控制和掺杂尤为重要。     

激光熔覆铁基合金涂层的高温氧化性能

通过在Fe基合金粉末中添加Cr3C2的方法,在35CrMo钢表面激光熔覆制备抗高温氧化Fe基合金复合涂层。采用扫描电镜(SEM)、能谱分析仪(EDS)、X射线衍射仪(XRD)等分析手段对激光熔覆层600℃氧化100h后的氧化膜形貌及成分进行分析,研究不同Cr3C2含量对抗高温氧化性能的影响。结果表明,激光熔覆Fe基合金涂层组织均匀致密,与基体结合良好,无裂纹、气孔等缺陷。在600℃下,Fe基合金涂层和添加Cr3C2的Fe基合金涂层的抗高温氧化性能均明显优于基体,其累计氧化增重及增重速率远远小于基体。Fe基合金熔覆层600℃氧化后表面形成了FeCr2O4尖晶石氧化物,具有较好的抗氧化能力。由于添加的Cr3C2熔覆过程中发生分解,使熔池中Cr元素含量提高,高温下试样表面形成连续完整的Cr2O3氧化膜,故添加Cr3C2的熔覆层的抗高温氧化性能提高。     

Achieving over 1,000 mW cm−2 Power Density Based on Locally High-Density Cross-Linked Polybenzimidazole Membrane Containing Pillar[5]arene Bearing Multiple Alkyl Bromide as a Cross-Linker

Cross-linking is widely accepted as an effective method to improve the mechanical strength and durability of phosphoric acid (PA) doped polybenzimidazole (PBI) membranes. However, the cross-linked membranes generally exhibit compromised overall performance since their compact network structures decrease the free volumes of membranes, leading to poor proton conductivity. In this study, a locally high-density cross-linked polybenzimidazole network based on pillar[5]arene bearing multiple alkyl bromide is constructed for the first time to achieve high proton conductivity, desired mechanical properties, and excellent fuel cell performance. The pillar[5]arene-cross-linked network considerably enhances the mechanical strength of membrane (14.6 MPa), particularly with high PA uptake, and provides loose PBI chain segment packing to retain PA (315.9%). Surprisingly, the pillar[5]arene-cross-linked PBI membrane displays a high-power density of 1,084.1 mW cm⁻² at 180 °C and 0.6 mg cm⁻² Pt loading without backpressure and humidification, that is the highest value reported in cross-linked membranes for high-temperature proton exchange membrane fuel cells.     

新型BNT系高温陶瓷电容器材料的研究

采用固相合成工艺,制备了(Bi0.5Na0.5)(1–x)CaxTiO3(BNCT)陶瓷(x=0.01～0.14)。研究了Ca含量对BNCT陶瓷介电性能的影响。结果表明,所有BNCT陶瓷样品中都存在第二相TiO2;随着Ca含量的增加,BNCT陶瓷的介电峰向低温方向移动,介温曲线越来越平坦,剩余极化急剧减小,介质损耗逐渐减小。往x=0.12的BNCT陶瓷里掺入质量分数为1.5%的MnCO3,所得陶瓷样品的室温tanδ小于1%、绝缘电阻率达到1011?.cm,并满足–55～+250℃下,?C/C25℃≤±15%的高温MLCC的要求。     

浅析铁锂电池在通信电源工程设计中的应用

在通信电源系统中,蓄电池组是必不可少的组成部分,是保证通信系统安全、可靠运行的关键。鉴于铅酸电池存在的问题。新型电池在不断研发。近年来,铁锂电池已逐步投入商用。文中就铁锂电池和铅酸蓄电池的特性进行对比分析,以及铁锂电池在通信电源系统运用中需要注意的问题进行了综合剖析。     

Planar Sodium-Nickel Chloride Batteries with High Areal Capacity for Sustainable Energy Storage

High-temperature sodium-nickel chloride (Na-NiCl₂) batteries are a promising solution for stationary energy storage, but the complex tubular geometry of the solid electrolyte represents a challenge for manufacturing. A planar electrolyte and cell design is more compatible with automated mass production. However, the planar cell design also faces a series of challenges, such as the management of molten phases during cycling. As a result, cycling of planar high-temperature cells until now focused on moderate areal capacities and current densities. In this work, planar cells capable of integrating cost-efficient nickel/iron electrodes at a substantially enhanced areal capacity of 150 mAh cm⁻² is presented. Due to a low cell resistance during operation at 300 °C, these cells deliver a specific discharge energy of 300 Wh kg⁻¹ at high discharge current densities of 80 mA cm⁻² (C/2, 10%–100% state-of-charge). This results represent the first demonstration of planar Na-NiCl₂ cells at a commercially relevant combination of areal capacity, cycling rate, and energy efficiency. It is further identified the secondary molten NaAlCl₄ electrolyte to contribute to the cell capacity during cycling. Mitigating electrochemical decomposition of NaAlCl₄ will play an important role in further enhancing both cycling rates and cycle life of high temperature Na-NiCl₂ batteries.     

高温超导微波滤波器研究进展

滤波器作为通信系统射频前端的关键部件,其性能至关重要。在微波频段,高温超导薄膜材料的表面电阻比普通金属铜低两个数量级以上。由于用高温超导体可以制备出性能优异的微波滤波器,并且现代无线通信系统多网络、多制式和多业务以及抗干扰的发展需求,使得小型多频带滤波器和具有抗噪声干扰的平衡滤波器的研究备受关注。研究团队长期从事该领域研究,并已取得一些研究成果。文章从不同谐振器结构类型以及频率特性等方面介绍了多频带和平衡滤波器的研究设计工作。     

The different influences of the two incorporation sites of B atoms on the mechanical and thermodynamic properties of B2–ZrCu compounds: a first-principle calculation

We applied a first-principle calculation to investigate the different influences of the two incorporation sites of B atoms on the mechanical and thermodynamic properties of the near-equiatomic B2–ZrCu compound. The alloying B atoms have two possible incorporation sites, namely, octahedral interstices and Cu sites. When the concentration of B atoms is lower than 5.882 at.%, interstitial B atoms will be effective at improving the bulk modulus (B), shear modulus (G) and Young’s modulus (E) of the B2–ZrCu parent. When the concentration of the substitutional B atoms is lower than 12.5 at.%, the ductility of the parent will be strengthened. The interstitial B atoms that are located at octahedral interstices in the 〈110〉 direction can remarkably improve the Debye temperature (Θ_D) of the substituted Zr₈Cu_8?zB_z phase. The prediction for the melting point shows that the high-temperature stability is strengthened with the increase of the B concentration. Interstitial B atoms are beneficial to the minimum thermal conductivity. Finally, the electronic properties are discussed in detail to further understand the mechanical properties.     

高温金属熔体黏度突变探索

高温金属熔体的黏度是衡量液态金属动力学性质的一个重要指标,是高温金属熔体的基本物理性能之一.熔体的黏度在表征脆性系数、金属玻璃形成能力的大小和液-液相变现象方面起关键性作用.本文在介绍高温金属熔体黏度测量方法的基础上,综合评述了单质、二元和多元合金黏度随温度的变化规律和黏度突变特征,分析了黏度突变研究的物理意义,并指出高温金属熔体黏度今后研究的发展方向。