稀散元素铼的分析进展

铼属于贵重稀散金属元素,铼的分析方法发展较快。本文综述了近年来国内外铼的分析进展,包括了矿样的分解、铼的分离富集以及铼的测定。     

CVD制备Ir/Re复合材料的显微组织和再结晶研究

采用CVD方法制备了Ir/Re复合材料。研究了Ir层中Ir晶粒的形貌和生长特点,计算得到Ir晶粒生长动力学方程:(x2-x02)/t=4.31×103exp(-2.65eV/kT)(μm2·s-1)。研究了CVD过程中Re层表面晶粒生长和V,W型浸蚀纹的关系。对靠近Ir层的细晶粒区和Re层中部的柱状晶粒区中Re晶粒的再结晶长大进行了研究,计算得到柱状晶区中Re晶粒的生长动力学方程:(x2-x02)/t=2.55×103exp(-1.52eV/kT)(μm2·s-1),研究了Ir/Re扩散、Re扩散对细晶区中Re晶粒生长动力学的影响。     

电子束悬浮熔炼钼铼合金铸锭的热加工方法

电子束悬浮熔炼钼铼合金铸锭晶粒粗大,致使热加工性能变差,锻造过程出现开裂,文章分析了锻造过程材料的受力状态,认为是垂直晶界的拉应力导致沿晶开裂,据此提出了热轧开坯的工艺方法,且规定第1道次平行铸锭轴向喂料,轧制过程中材料产生剪切滑移变形,滑移面与晶界成一定夹角,不产生垂直晶界的拉应力,避免了拉应力作用下的沿晶开裂,获得优质热轧板。     

铼的分离分析方法研究进展

介绍了萃取分离、离子交换、液膜分离、活性炭吸附等四种铼的主要分离富集方法,以及分光光度法、等离子体-质谱法等铼的分析方法,指出了不同方法的特点及使用范围,并展望了铼的分离分析方法的发展方向。     

特殊场合下的温度测量技术

对于测量条件恶劣,不能用常规传感器实现的特殊场合,如高温强腐蚀性介质、真空、高温熔体及核辐射条件下的温度测量,必须开发特种专用传感器。本文阐述了钨铼热电偶等特种温度传感器的特点、性能及应用,并着重探讨了当前测温领域热点问题。铝液、铜液及熔盐等高温溶体连续测温;高温渗碳、真空粉末治金烧结炉(气)等强还原性气氛下的温度测量：流化床等流动粉体等高温强磨损条件下的温度测量技术等。实践证明,新开发的特殊场合下专用温度传感器,不仅与国际接轨,替代进口产品,而且还可以打入国际市场。     

SEPARATION OF Re AND Mo BY ADSORPTION OF ACTIVE CARBON

Separation of Re and Mo by adsorption of active carbon has been studied. The results show that Re and Mo can be separated effectively by adjusting the pH value. As pH>8.2. the coefficient of separation S_(Rc)/Mo>3.042. The adsorption isotherm for Re conforms to the Freundlich formula.     

Contribution of electrospray mass spectrometry for the characterization, design, and development of nitrido technetium and rhenium heterocomplexes as potential radiopharmaceuticals

Diagnostic nuclear medicine (NM) is among the imaging procedures (together with X-ray, computerized tomography, magnetic resonance, and echography) the clinicians can routinely adopt to image organs or tissues and related disorders. (99m)Tc-based agents are the radiopharmaceuticals of election in diagnostic NM because of the ideal physical properties of the 99mTc nuclide (t1/2 6.01 hr; Egamma 142 keV), low cost, and easy availability through the commercial 99Mo/99mTc generator, and chemical versatility of the element. In the last two decades the synergistic work of clinics, pharmacologists, and coordination chemists has had a tremendous impact in the development of new 99mTc-based radiopharmaceuticals through the recognition of the structure at the molecular level of the agent utilized. This has been achieved by studying the physico-chemical properties of the long-lived 99gTc (t1/2 2.11 x 10(5) year; Ebeta 292 keV) and third-row congener Re isostructural compounds. Electrospray ionization mass spectrometry (ESI-MS) and collision experiments (MS/MS) represent valuable analytical techniques suitable for the characterization of both technetium and rhenium complexes relevant to NM. Unequivocal structural identification of these bioinorganic compounds, either simple coordination complexes ("essential radiopharmaceuticals") or more sophisticated structures carrying bioactive fragments ("receptor-specific" radiopharmaceuticals), can be realized in combination with multinuclear NMR spectroscopy. MS/MS experiments provide useful information on the different metal-ligand bond strength, and comparison of the fragmentation profiles of isostructural technetium and rhenium compounds give additional details on the role played by the metal in determining preferred decomposition channels. The analysis of these data contribute to design novel synthetic strategies for the obtainment of technetium and rhenium compounds relevant to NM. The chemistry underlying the production of a new class of potential radiopharmaceuticals including a terminal nitrogen bond and a mixed coordination sphere comprising heterodiphosphines and/or dithiocarbamates (DTC) is presented in detail together with the ESI-MS and MS/MS investigations.     

长碳链烯烃歧化研究进展

目前,虽然直链烯烃歧化研究的重点仍是碳四烯烃歧化制丙烯技术,但是长碳链烯烃歧化研究已开始引起人们的重视。本文介绍了铼基催化剂、钼基催化剂和钨基催化剂催化长碳链烯烃歧化反应的研究进展。重点介绍了钨基催化剂上长碳链歧化研究状况,分别介绍了钨基催化剂上1-己烯自歧化、1-庚烯自歧化、1-辛烯自歧化的最优工艺条件研究以及预处理条件对钨基催化剂歧化性能的影响。同时分别介绍了含氧化合物对歧化催化剂中毒失活的研究以及钨基催化剂上结焦失活的研究状况。     

Effects of Re and Ru Additions on Solidification Partition Coefficients and Solidification Characteristic Temperatures of Nickel Base Single Crystal Superalloys

采用双区加热和液态金属冷却相结合的定向凝固方法,制备出4种Re和Ru含量不同的平界面态镍基单晶高温合金,精确测定了近平衡凝固时合金中各元素的平衡分配系数和合金的凝固特征温度。结果表明:Re的添加将显著降低重偏析元素Re、W和Ta的偏析程度,使液相线温度先降低后升高,而固相线温度始终降低;Ru的添加对偏析的影响较小,并略微降低合金的液相线和固相线温度。同时,根据平衡分配系数和凝固特征温度可预测非平衡凝固态单晶合金的元素偏析和凝固缺陷形成倾向。     

Enrichment of 41K isotope in potassium formed on and in a rhenium electrode during plasma electrolysis in K2CO3/H2O and K2CO3/D2O solutions

It was found that potassium forms on rhenium electrodes during plasma electrolysis in K₂CO₃/H₂O and K₂CO₃/D₂O solutions, and the new potassium has unnatural isotopic ratios. The isotope ⁴¹K increases from the natural abundance, 6.7%, to as much as 32–37%. The percentage of ⁴¹K in the potassium contamination in a rhenium electrode before electrolysis was close to the natural isotopic abundance (6.7%). This result suggests that the ⁴¹K was enriched by some unknown process connected with a vigorous discharge of plasma electrolysis.