催化极谱法测定矿石中微量铼方法改进

采用2.5次微分催化极谱法,在硫酸—硫酸羟胺—硫酸钠—抗坏血酸—碲(Ⅳ)混合底液中,在国产JP3-1型极谱仪上,于起始电位-0.700伏,终止电位-1.200伏,测定矿石中微量铼。铼浓度在0—15μg/25m l可保持线性关系,且灵敏度高,重现性好,完全满足钼矿、辉钼矿中,以及其他矿物中微量铼的测定。     

Sintering of highly porous silica-particle samples: analogues of early Solar-System aggregates

I describe a new method to make particle layers which consist of SiO₂ spheres with 0.78 μm radius. The layers were produced by sedimentation of aggregates which had grown in ballistic particle collisions, and the layers had a porosity of 0.95. They were used for experiments on sintering, i.e., the samples were heated in an oven at varying temperatures and heating durations, and the samples were analyzed by scanning electron microscopy. Based on the change of particle diameter, surface diffusion sintering and viscous flow are identified as important transformation mechanisms. The first effect dominated at the start of restructuring and the latter at higher temperatures. The neck growth of adjacent particles was fitted to a surface diffusion sintering model and predicts neck radii as a heating temperature and duration function. Between the temperature range of neck formation and of melting, further restructuring occurred which lead to dissolution of particulate structure and to densification and which resulted in a porous object consisting of straight elongated substructures which connected kinks of higher material density. The thermal transformation is important for the change of strength, collisional behavior, light-scattering properties, and thermal conductivity with relevance to dust aggregates, planetesimals, comets, interplanetary dust particles, and regolith-covered celestial bodies.     

接触岩面烧结与地壳深部地震机制

玄武岩、花岗岩、闪长岩以及安山岩的接触面,在350℃—900℃,1×10~8—4×10~8帕围压下,经过1—35天,便烧结成一个整体,并具有很高但低于原岩的剪切强度。此强度随温度、围压和时间的增加而增大。在烧结面与主压应力方向夹角大于55°时,便不再断裂,而沿其它方向剪断。烧结过程中,没有新矿物产生,也没有矿物熔融作用参与,但岩石密度增加,晶粒长大。晶粒粘附作用和原子体积扩散是烧结的物理机制,晶粒表面能自发地从高向低转化,是促进烧结的基本动力。烧结面的再破裂和延裂便是断裂带在地壳深部重复发生地震的主要机制。实验最低温度和围压相当地壳十公里深,这应是深大断裂的上部裂面与下部烧结层的界限,受载后便向下延裂,而在下部形成地震震源。这可能是地壳中震源多在15—25公里深的重要原因。     

Petrography of Yamato 984028 lherzolitic shergottite and its melt vein: Implications for its shock metamorphism and origin of the vein

Yamato 984028 (Y984028) is a newly identified lherzolitic shergottite, recovered from the Yamato Mountains, Antarctica, in 1999. As part of a consortium study, we conducted petrographic observations of Y984028 and its melt vein in order to investigate its shock metamorphism. The rock displays the typical non-poikilitic texture of lherzolitic shergottite, characterized by a framework of olivine, minor pyroxene (pigeonite and augite), and interstitial maskelynite. Shock metamorphic features include irregular fractures in olivine and pyroxene, shock-induced twin-lamellae in pyroxene, and the complete conversion of plagioclase to maskelynite, features consistent with those found in other lherzolitic shergottites. The melt vein is composed of coarse mineral fragments (mainly olivine) entrained in a matrix of fine-grained euhedral olivine (with several modes of compositional zoning) and interstitial glassy material. Some coarse olivine fragments consist of an assemblage of fine-grained euhedral to subhedral olivine crystals, suggesting shock-induced fragmentation, recrystallization, and/or a process of sintering. The implication is that the fine-grained olivine crystals in the matrix of the melt vein represent complicated crystallization environments and histories.     

Fabrication of dense forsterite–enstatite polycrystals for experimental studies

 A practical and reliable method for the preparation of fine-grained forsterite and forsterite–enstatite polycrystals, in the system MgO–SiO₂, is described. The method employs state-of-the-art techniques from materials science, namely sol-gel synthesis, powder processing and sintering. The resulting dense polycrystalline materials are homogeneously fine-grained (1–2 μm) and uniformly foam-textured. Moreover, they are highly reproducible in composition and microstructure. The enstatite content can be controlled to within ∼1%, in the range 0–50%, and densities up to 98% of theoretical density can be achieved. The method thus yields polycrystalline forsterite–enstatite material suitable for a range of geochemical, petrological and geophysical studies. Received: 19 October 1999 / Accepted: 18 June 2001     

水冷式工频大电流烧结机的研制

随着我国石材工业的发展，为满足石材加工设备的大量需求，研制了水冷式工频大电流烧结机。该机采用水冷式变压器（目前国内其它烧结机为风冷式变压器）。副边水冷绕组与原绕组相互叠合，达到初次级绕组同时冷却效果。有效地降低了次级线圈内阻，减少损耗，使其发挥最大效率。并可以连续方便地调整加热功率，实现温度调节、温度测量、保温自动控制和保温时间控制，以满足金刚石石材切割工具烧结的不同工艺要求。在推向市场的几年中，证明该机具有加热功率大、体积小、升温快，控制温度准确、操作简便和成本低的特点。是目前国内烧结金刚石工具较先进的设备。该机在十几个省市推广应用中，获得了较好的经济效益和社会效益，同时也推动了我国金刚石制品行业的发展。     

Recycling of harbor sediment as lightweight aggregate

Sediment sampled from Taichung Harbor was mixed with local reservoir sediment at different weight ratios to prepare lightweight aggregate at 1050, 1100, and 1150 degrees C. A pressure of 3000 or 5000 psi was used to shape the powder mixtures into pellets before the heating processes. The results indicate that the leaching levels of trace metals from the lightweight aggregate samples are considerably reduced to levels less than Taiwan Environmental Protection Administration regulatory limits. Increasing final process temperature tends to reduce the bulk density and crushing intensity of lightweight aggregate with a concomitant increase in water sorption capability. Lightweight aggregate with the lowest bulk density, 0.49 g cm(-3) for the 5000 psi sample, was obtained with the heating process to 1150 degrees C. Based on the X-ray absorption near edge structure results, FeSO(4) decomposition with a concomitant release of SO(x) (x = 2,3) is suggested to play an important role for the bloating process in present study.