我国稀土放射性核素研究进展

综述了我国稀土矿中伴生的天然放射性核素的种类、放射性强度及其加工利用过程中核素迁移及演变规律的研究进展,提出该领域重要的研究发展方向为:①分析确定各种稀土矿天然放射性核素种类和辐射性质;②研究南方离子型稀土提取利用过程中放射性核素迁移与演变规律;③建立放射性核素分布数据库.     

硅对易切削Bi黄铜组织及性能影响的研究

用PHILIPS-XL30型扫描电子显微镜（SEM）观察了不同硅含量对易切削铋黄铜组织的影响,采用HY-1080型电子拉伸试验机测试各试样的力学性能,使用C6136卧式普通机床检测合金切削性能.结果表明：硅的加入使铋黄铜中的β相比例增加,α相比例减少;铋黄铜的伸长率、断面收缩率随着硅含量的增加而下降,而材料的抗拉强度随着硅含量的增加而增加;铋黄铜的切削性能随着硅含量的增加而增加.     

助熔剂对Y_3Al_5O_（12）：Ce荧光粉的影响

采用高温固相反应法合成了黄色荧光粉Y3Al5O12：Ce,研究了助熔剂对Y3Al5O12：Ce荧光粉发光特性的影响.XRD的测量结果表明加入合适的助熔剂有利于荧光粉的晶化,并且不引入杂相.选择H3BO4和SBL同时使用效果要好于单独使用一种助熔剂.助熔剂的加入可增大荧光粉的激发和发射光谱强度,并能有效降低荧光粉的中心粒径.     

声波透射法分析桩身混凝土质量的相对强弱指标法

介绍了传统桩基检测中判别桩身混凝土质量的判据方法,在此基础上提出了一种新的参数分析方法——相对强弱指标法.这种方法综合了声速、波幅、频率、声时、PSD多方面的因素,通过比较,它比以往的判别方法更能够准确地对桩基质量进行定性分析,并且还能进行一定的定量分析.经过取芯验证,证实此法确实可行有效,有一定的实用价值.     

某低品位难选白钨矿常温浮选试验研究

江西某白钨矿石含钨0.23%,原矿钨品位低、嵌布粒度较细、萤石含量高,是典型的白钨-方解石-萤石（或重晶石）型难选白钨矿.针对该难选白钨矿中有价金属钨无法有效回收的现状,对其进行了试验研究,结果表明,采用组合药剂（GYW＋731）做捕收剂,新型药剂WH做活化剂,实现了该低品位难选白钨矿的常温浮选,闭路试验获得了品位为35.11%,回收率为72.20%的钨精矿.     

某石灰岩矿中深孔爆破参数优化研究

针对某石灰岩矿劳动强度大、生产效率低、安全条件差的开采现状,应用中深孔房柱法,借鉴露天台阶爆破参数设计及优化方法,通过正交试验法对抵抗线、孔排距、堵塞长度等3个影响爆破效果主要因素进行优选,并进行了爆破震动测试．确定了合理的中深孔凿岩爆破参数,降低了爆破大块率,改善了爆破效果,降低了矿山成本．     

化学共沉淀法制备纳米级NiFeCo合金前驱体的热力学分析

根据同时平衡原理和质量守恒定律,建立了25℃时Me2+-CO23--NH3-H2O(Me2+=Fe2+,Ni2+,Co2+)体系中各种金属总离子浓度与pH的关系,绘制了不同[Ct]和[N]t条件下各金属离子的lg[Met]-pH图。热力学分析表明:增加溶液中总碳浓度或减少总氨浓度,有利于金属离子的共沉淀;当溶液中[Ct]和[N]t分别控制在1.0mol/L和0.2mol/L时,Fe2+、Co2+和Ni2+共沉淀的最佳pH范围为7～8,此时溶液中残余金属离子总浓度在0.1mmol/L以下。     

Synthesis and luminescence properties of BaWO4：Pr^3＋ microcrystal

BaWO4:Pr3+ (hereafter BWO:Pr) microcrystals were prepared via a hydrothermal route, and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence excitation and emission spectra. The as-prepared products with different morphologies of egg-shape rod, olive-like, and quasi-sphere were obtained by the addition of the surfactants and chelating agents. The emis-sion spectra of BWO:Pr microcrystals showed the strong red emission (642 nm) assigned to the Pr3+ ions of 3P0→3F2 transition with blue ex-citation (484.6 nm, 3H4→3P0).     

The use of metal hydride powder blending in the production of NdFeB-type magnets

The ability to vary the composition of NdFeB-type magnets, during or after the milling stage offers a number of advantages. To this end, powder blending processes have been developed. In the present work, the sintering characteristics of a Nd₁₃Fe_80.5B_6.5 alloy have been improved by powder blending with neodymium hydride. A blending addition of 1 at% of neodymium in the form of Nd-hydride, consistent with a final composition of Nd₁₄Fe_79.6B_6.4, was sufficient to reduce the required sintering temperature from 1130 to 1070°C, with a resultant improvement in the coercivity due to less grain growth and better grain isolation. The addition of dysprosium hydride to a Nd₁₄Fe₇₉B₇ alloy by blending resulted in a further enhancement of the coercivity, a 2 at% addition yielding an approximate doubling in the value of intrinsic coercivity. Examination of the microstructure of dysprosium–hydride blended magnets showed the dysprosium to be concentrated in the outer regions of the matrix grains, with the centres being essentially dysprosium-free. Hydrogen has also been employed in improving the milling characteristics of the high melting point elements niobium and vanadium. Fine powders of niobium and vanadium hydride were prepared and were successfully blended into magnets with an even distribution throughout the microstructure. These studies have shown that powder blending of metal hydrides is an effective way of both promoting liquid-phase sintering in low rare earth composition magnets and of modifying the grain boundary phases and hence the magnetic properties.     

Radiation-induced branching and crosslinking of poly(tetrafluoroethylene) (PTFE)

The effect of electron beams on poly(tetrafluoroethylene) (PTFE) at elevated temperatures above the melting point on oxygen-free conditions has been studied using differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS), Fourier-transform infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA) and tensile test. The investigations have shown that the chemical structure and several properties of PTFE are greatly altered by the irradiation. DSC and WAXS indicate that the crystallinity of the PTFE irradiated with high doses is reduced. CF₃ side groups and branched structures are assumed to hinder the crystallization. TGA has shown that the thermal stability of the radiation-modified PTFE is considerably lower than that of unirradiated PTFE.