高温光纤光栅的研究进展

为了满足航空航天、导弹制导、冶炼等一些高温领域的传感测量需求,国内外学者对高温光纤光栅进行了大量的研究工作。对已报道的主要的高温光纤光栅进行了综述,按照光栅结构、特点和所用光纤的不同,将其分为Ⅱ型光纤光栅、ⅡA型光纤光栅、化学组分光纤光栅、掺杂特殊离子的光纤光栅、结构变化型长周期光纤光栅等,逐类进行了说明并对它们的制作方法、高温特性、优缺点等进行了介绍和简评,并对其发展前景和应用进行了展望。     

Probing phase transitions under extreme conditions by ultrafast techniques: Advances at the Fermi@Elettra free-electron-laser facility

Novel possibilities for studying matter under extreme conditions are opened by the forthcoming availability of free electron laser (FEL) facilities generating subpicosecond photon pulses of high intensity in the VUV and X-ray range, which are able to heat thin samples up to the warm dense matter (WDM) regime. Pump-and-probe ultrafast techniques can be used to study the dynamics of phase transitions and characterize the states under extreme and metastable conditions. Ultrafast (10-100 fs) bulk heating is seen as a novel route for accessing extremely high temperature regimes as well as the transition region between low-density and high density fluids, that is presently considered a no man's land in simple liquids and glasses. Here we briefly describe the present status of the TIMEX end-station devoted to those experimental activities at the Fermi@Elettra FEL facility, and some preliminary results obtained in a pilot ultrafast experiment using a laser source as a pump and a supercontinuum probe aimed to characterize the melting process of Silicon.     

LixZryOz三元化合物的制备及表征

采用高温固相法制备了4种高纯度晶相组成的LixZryOz三元化合物,研究了焙烧温度、时间、反应物的种类和初始反应物物质的量比对产物组成的影响,进一步用XRD、SEM及BET分析方法对产物的晶相结构、表面形貌及比表面积进行了表征.实验结果表明,Li2CO3与ZrO2在适当条件下可以合成得到单斜相Li3ZrO3;以LiOH替代Li2CO3,在适当条件下可以分别合成得到四方相Li2ZrO3和三斜/单斜相Li6Zr2O7;进一步以Zr(NO3)4·5H2O代替Zr02,可将单斜相Li6Zr2O7的制备时间由96 h缩短至24 h.SEM照片显示产物硬团聚明显,粒径分布在1～10μm间,BET分析表明样品比表面积处于1.0～9.0 m2·g-1间分布,反应过程中锂的过量以及长时间高温焙烧是引起产物粒径长大和产生硬团聚的主要原因.     

High-temperature proton conductors with structure-disordered oxygen sublattice

Data on the thermogravimetry, spectroscopy, and electrical charge transfer as functions of T, aH₂O, and aO₂ for niobates and tantalates of alkali-earth metals with structure disordering of the oxygen sublattice, which can show high-temperature proton conduction, are summarized. It is shown that in the solid solution series with decreasing x (that is, with the increasing of the oxygen vacancies concentration) the proton conductivity increase, which is caused by the increasing of both the concentration of proton defects formed in the structure (in compliance with the formula Sr_{6 ? 2x} M _{2 + 2x} ⁺⁵ O₁₀(OH)_2?6x and their mobility. The proton transfer dominates for the compositions with x < 0.15 at temperatures below 550°C. In the solid solutions (Ba_1?y Ca _y )₆Nb₂O₁₁ (0.23 ≤ y ≤ 0.47) characterized by equal concentration of oxygen vacancies, with the increasing of barium content (correspondingly, with the increasing of the lattice parameter) the oxygen-ion conductivity (at aH₂O = 3 × 10^?5) grows monotonically, which is caused by the decreasing of the oxygen atom migration energy and increasing of their mobility. In this series, the proton conductivity (at aH₂O = 2 × 10^?2) increased. It was shown, by using IR-spectroscopy and the ¹H NMR method, that the protons exist in the complex oxide structure mainly as energy-wise nonequivalent OH^? groups: isolated, closely set, and paired, whose quantitative ratios are determined by the coordination preference of the B-sublattice elements.     

基于高温超导双晶结的约瑟夫森效应观测实验

基于YBa2Cu3O7-δ高温超导双晶结,组建了约瑟夫森效应测试装置.利用此装置观察了直流和交流约瑟夫森效应,并测量了约瑟夫森结的临界电流和夏皮罗台阶.     

Heavy-Ion Collisions toward High-Density Nuclear Matter

In the present paper, the current efforts in heavy-ion collisions toward high-density nuclear matter will be discussed. First, the essential points learned from RHIC and LHC will be reviewed. Then, the present data from the STAR Beam Energy Scan are discussed. Finally, the current efforts, NICA, FAIR, HIAF, and J-PARC-HI (heavy ion) are described. In particular, the efforts of the J-PARC-HI project are described in detail.     

镍合金基自润滑复合材料的研究

作者根据发动机配气阀座在高温、高压、高速等苛刻条件下使用的技术要求,以摩擦学原理为指导进行配料,利用粉末冶金热压成型工艺制备出含银和石墨的镍合金基自润滑复合材料,并由该材料制作配气阀座实现其自润滑。研究结果表明,所研制的3种镍合金基自润滑复合材料都可顺利通过一个全程430秒的马力试验而毫无开裂,其中镍合金:银:石墨—70:15:15②材料具有机械强度高、摩擦系数低、耐磨性好、组织均匀、性能稳定、重现性好、易机加工和成品率高等优点,可连续运行3个全程以上,与其对摩的TZM合金阀体也可运行3个全程以上,它们的总磨损量均在机加工公差范围内。本文报道的是一项开创性的工作,在高温耐磨自润滑材料的研制方面开辟了一条新的技术途径,具有明显的技术和经济效益。     

Reverse Engineering Analysis of the High-Temperature Reversible Oligomerization and Amyloidogenicity of PSD95-PDZ3

PSD95-PDZ3, the third PDZ domain of the post-synaptic density-95 protein (MW 11 kDa), undergoes a peculiar three-state thermal denaturation (N ↔ I_n ↔ D) and is amyloidogenic. PSD95-PDZ3 in the intermediate state (I) is reversibly oligomerized (RO: Reversible oligomerization). We previously reported a point mutation (F340A) that inhibits both ROs and amyloidogenesis and constructed the PDZ3-F340A variant. Here, we “reverse engineered” PDZ3-F340A for inducing high-temperature RO and amyloidogenesis. We produced three variants (R309L, E310L, and N326L), where we individually mutated hydrophilic residues exposed at the surface of the monomeric PDZ3-F340A but buried in the tetrameric crystal structure to a hydrophobic leucine. Differential scanning calorimetry indicated that two of the designed variants (PDZ3-F340A/R309L and E310L) denatured according to the two-state model. On the other hand, PDZ3-F340A/N326L denatured according to a three-state model and produced high-temperature ROs. The secondary structures of PDZ3-F340A/N326L and PDZ3-wt in the RO state were unfolded according to circular dichroism and differential scanning calorimetry. Furthermore, PDZ3-F340A/N326L was amyloidogenic as assessed by Thioflavin T fluorescence. Altogether, these results demonstrate that a single amino acid mutation can trigger the formation of high-temperature RO and concurrent amyloidogenesis.     

精铸热锻模具钢的合金成分设计及其高温磨损性能研究

探讨了精铸热锻模具钢合金化设计的依据和合金成分设计较佳的参数范围,开发出高耐磨精铸热锻模具钢,采用MG-2000型销-盘式高温摩擦磨损试验机在干摩擦、400℃条件下,研究了精铸热锻模具钢的高温磨损性能.结果表明:合金成分设计参数应控制为V/C在3.00～3.60之间,C余在0.10～0.25之间,Cr/Cr Mo在0.68～0.85之间,Cr/C余＞16.60,Mo/C余＞16.00;所研制的精铸热锻模具钢的淬火组织为马贝复相组织,回火后碳化物以弥散析出的V4C3为主,含有少量Cr和Mo的碳化物,Cr、Mo主要固溶于α-Fe中,以保证精铸热锻模具钢的热强性和热稳定性;精铸模具钢具有较好的高温耐磨性,磨损率明显低于H13钢.其磨损机制为氧化磨损,即在精铸热锻模具钢的高温磨损表面形成Fe3O4和Fe2O3.     

单晶光纤制备及高温传感器研究进展

单晶光纤(single-crystal fiber),是一种纤维形态的晶体材料,凭借优异的物理和化学性能以及大长径比的结构特点在国防及民生领域都有着广泛的应用前景。随着导模法、激光加热基座法以及微下拉法等生长技术的日渐成熟,单晶光纤迎来了科学研究和应用发展的黄金时期,其材料种类以及应用方向均呈现多元化发展态势,其中面向高温传感领域的高熔点氧化物单晶光纤凭借其耐高温、抗氧化、结构紧凑等特点在强氧化、强辐射、强腐蚀、强电磁干扰等极端环境中展现出了巨大的应用潜力。近年来,研究者们不断将光学、声学等传感技术与单晶光纤介质相结合,在保持传感器结构灵活性的基础上,拓宽了常规玻璃光纤传感器的使用温度,同时弥补了热电偶等传统接触式测温技术在恶劣环境中寿命较低的缺陷。本文以单晶光纤的制备技术为出发点,回顾了单晶光纤的发展历史,分析了单晶光纤三种主要制备方法的技术特点及发展现状。同时,总结了单晶光纤在高温传感领域的主要研究成果,展望了单晶光纤高温传感技术的应用前景。