惯性约束聚变靶用空心玻璃微球的干凝胶法制备技术

干凝胶法是我国目前制备惯性约束聚变(ICF)靶用空心玻璃微球(HGM)的主要方法,其制备的HGM可在较宽的范围内满足ICF物理实验的要求。从干凝胶粒子/微球的溶胶-凝胶法制备技术和HGM的炉内成球原理出发,系统综述了近三十年来ICF靶用HGM干凝胶法制备技术研究的相关报道,分析总结了干凝胶法制备技术在HGM成分设计、元素掺杂、直径及球形度、壁厚及均匀性、耐压强度、渗透性能、表面粗糙度、性能一致性等方面的技术现状及难点,对干凝胶法制备HGM技术的瓶颈性问题及可能的解决方案进行了讨论。     

液滴法制备空心玻璃微球中初始液滴的定量形成

通过对液滴法制备激光聚变靶丸空心玻璃微球（HGM）中液滴形成过程予以分析,导出了射流初始速率、液滴直径及目标HGM直径分别与进为压力、小孔板孔径、射流振荡频率、溶液浓度及密度等因素的定量表达式,并在进料压力为13．7、18．7、23．6、28．5、33．4、38．3、43．2kPa和溶液中玻璃形成物浓度为1％、2％、4％、6％、8％、12％、16％下,测量了孔直径分别为108μm、142μm和168μm的小孔板的流量及流动系数,给出了射流初始速率、液滴直径及目标HGM中玻璃形成物含量的定量控制条件,实验结果符合定量表达式。     

干凝胶法制备惯性约束聚变靶用高渗透性空心玻璃微球

为制备惯性约束聚变靶用高渗透性空心玻璃球（hollow glass microspheres,HGM）,研究了初始玻璃配方、发泡剂种类、炉内载气组分和压力、精炼温度对干凝胶粒子的炉内成球过程和最终HGM的产率、质量和渗透性能的影响。结果表明：初始玻璃配方中的绝大部分碱金属氧化物在精炼过程中都从液态玻璃挥发进入载气,最终...     

干凝胶法制备惯性约束聚变靶用大直径空心玻璃微球

为实现惯性约束聚变靶用大直径空心玻璃微球的干凝胶法制备,从数值模拟和工艺实验2个方面研究了发泡剂种类及含量、炉内载气组分、压力和温度对大直径空心玻璃微球制备过程的影响。结果表明:采用碱金属的乙酸盐作为发泡剂可以显著提高干凝胶粒子的发泡效率,提高载气中的氦气含量和升高炉温可以提高干凝胶粒子在吸热阶段的升温速率、更为迅速有效地完成封装过程,从而有利于大直径空心玻璃微球的制备。虽然降低载气压力有利于显著增大空心玻璃微球的直径,但是空心玻璃微球的品质急剧下降。当载气中氦气的体积分数为50%～80%、载气压力为(0.75～1.0)×105Pa、炉温为1500～1700℃时,干凝胶粒子的成球率较高、大直径(700～1000μm)空心玻璃微球的球形度、同心度和表面光洁度较好。     

氘气透过高纵横比空心玻璃微球的实验研究

为了测试用于激光聚变实验的高纵横比空心玻璃微球(HGM)对D2气保气性能及计算HGM内D2剩余量,对3种常用配方HGM及其用0.5MNH4F＋0.1MHNO3洗液在90℃下处理后的HGM分别在573K下分三步热扩散充D2气,然后在290K下分别在0h、72h、144h时用气泡法测量HGM内的D2气压,由此测定了D2气体透过HGM的充气速率和漏气速率及其表观扩散活化能,并给出它们对D2保气半时间或充气半时间随HGM直径、壁厚和温度变化的计算式。     

氚气透过高纵横比空心玻璃微球的实验研究

为了测试用于激光聚变实验的高纵横比空心玻璃微球（HGM）对D2气保气性能及计算HGM内D2剩余量，对3种常用配方HGM及其用0.5MNH4F 0.1MHNO3洗液在90℃下处理后的HGM分别在573K下分三步热扩散充D2气，然后在290K下分别在0h、72h、144h时用气泡法测量HGM内的D2气压，由此测定了D2气体透过HGM的充气速率和漏气速率及其表观扩散活化能，并给出它们对D2保气半时间或充气半时间随HGM直径、壁厚和温度变化的计算式。     

空心玻璃微珠对膨胀阻燃聚丙烯材料的阻燃协效研究

采用三嗪成炭剂(CFA)和聚磷酸铵(APP)制备膨胀阻燃剂(IFR),将空心玻璃微珠(HGM)加入IFR进行协效阻燃,探讨HGM对PP/IFR/HGM的氧指数、垂直燃烧、热降解行为、炭层形貌的影响。结果表明:PP/IFR/HGM(5%)复合材料的LOI为32.6%,1.6 mm样条垂直燃烧通过V-0级。PP/IFR/HGM(5%)最大热失重温度为494.3℃,800℃残炭率为9.5%,与纯PP相比,热分解速率降低,热稳定性提高,残炭量增多。HGM的加入使复合材料的阻燃性能明显提高,PP/IFR/HGM(5%)热释放速率峰值为183 kW/m2,总热释放量为3 456.2 MJ/m2。空心玻璃微珠使PP/IFR/HGM(5%)复合材料的炭层更致密。     

漂浮型TiO2/石墨烯复合催化剂的制备及其性能

以空心玻璃微珠(HGM)为载体,采用水热法制备漂浮型石墨烯(RGO)-TiO_2复合光催化剂。首先将超声分散后的氧化石墨烯(GO)负载于经预处理后的HGM表面,而后以钛酸四丁酯为前驱体,在不使用还原剂条件下采用一步水热法制备出TiO_2/RGO/HGM复合光催化剂。研究了压力、GO(RGO)含量对复合光催化剂性能的影响。以罗丹明B(RhB)为降解对象分析了复合光催化剂的光催化降解效果。结果表明:GO成功负载于空心玻璃微珠表面,并通过水热过程在空心玻璃微珠表面原位还原生成RGO,二氧化钛形成RGO/HGM复合结构。此后,锐钛矿型TiO_2在RGO/HGM复合结构表面自组装成核并均匀负载从而形成TiO_2/RGO/HGM复合光催化剂。与TiO_2/HGM复合材料相比,TiO_2/RGO/HGM复合材料具有增强的光催化降解活性,再循环后具有良好的降解效果。此外,还提出了加载在HGM表面的RGO和TiO_2的可能机理和形成过程。     

PBT/空心玻璃微珠复合材料的性能研究

采用不同硅烷偶联剂对空心玻璃微珠(HGM)进行表面改性,制备了聚对苯二甲酸丁二醇酯(PBT)/改性HGM复合材料.结果表明:改性HGM的加入,提高了复合材料的弯曲强度和拉伸强度,并有效降低了其密度,同时复合材料的冲击强度下降;HGM表面经SG-700型硅烷偶联剂处理后对PBT填充改性的效果较好.     

空心玻璃微珠/PA66复合材料的性能研究

采用空心玻璃微珠(HGM)填充聚酰胺66(PA66),经挤出注塑制得改性PA66复合材料,通过一系列测试方法研究了HGM用量和表面处理方式对复合材料的力学性能、密度和吸水率的影响。结果表明,随着HGM含量的增加,复合材料的拉伸强度、弯曲强度和硬度均增加,在HGM质量分数为10%时达到最大值;密度和吸水率则减少,缺口冲击强度也有所下降。     

Fabrication and characterization of millimeter-sized glass shells for inertial confinement fusion targets

To fabricate target quality millimeter-sized glass shells for inertial confinement fusion (ICF) fuel micro-containers by sol–gel technology, the effects of gel particle properties and processing parameters on the diameter, quality and yield of resulting glass shells were investigated by simulation and experiments. The results show that the initial compositions and sizes of the gel particles, the blowing agents, the pressures and compositions of furnace atmosphere, the refining temperatures and the lengths of refining zone are the key parameters to obtain target quality millimeter-sized glass shells. Increasing the gel particle sizes and/or lowering the furnace atmosphere pressures, the resulting glass shell diameters increase rapidly but the sphericity, wall uniformity and surface finish decrease notably. Displacing argon gas with helium gas in the furnace atmosphere can significantly improve the glass shell diameters, quality and yields; however, keeping appropriate fraction of argon gas in the furnace atmosphere can reduce the fragmentation of the gel particles and the ripples and collapse on the shell walls. The quality and yields of the resulting glass shells can also be improved by increasing the temperatures and lengths of the refining zone.     

激光聚变靶用空心玻璃微球的成分设计

基于玻璃成分与性能之间的定量关系,以高强度、高化学稳定性、易熔和低粘度为目标,应用正交试验法对30种待选玻璃配方中Na2O、K2O、Al2O3、CaO的含量进行了优化,从中优选出了10种玻璃配方作为激光聚变实验靶用空心玻璃微球的候选配方.与国内外其它靶用空心微球玻璃的性能相比,候选配方的玻璃不仅化学稳定性和抗张强度有显著提高,而且各自的熔化温度、粘度等参数也满足空心玻璃微球炉内成球法的工艺要求.     

Preparation of lightweight hollow glass microsphere ceramics by gel casting

Owing to low density, hollow glass microspheres (HGMs) float on common media such as water, ethanol, and tertiary butanol. As a result, HGMs are not suitable to prepare slurries and ceramics by gel, slip, and freeze castings. In this paper, polyacrylamide (PAM) was used as dispersant and thickener agent to prepare homogeneous HGM aqueous slurries with controlled solid loadings and subsequent lightweight HGM porous ceramics were prepared by gel casting. Effects of PAM content on the stability of aqueous slurries as well as effects of solid (i.e., HGM) loading on density, porosity, pore size distribution, and compressive strength of porous ceramics were investigated. Increasing the viscosity of the slurry resulted in HGMs with significantly lower floating rates and more stable HGM aqueous slurries. HGM porous ceramics with densities and compressive strengths of 0.127–0.219?g/cm³ and 0.74–1.71?MPa, respectively, were prepared by gel casting.     

Developing a hollow glass microsphere/geopolymer thermal insulation composite for hot metal surface coating

Manufacturing inorganic thermal insulation materials with superior properties such as low thermal conductivity (k < 0.1 W/mK) and high mechanical properties in terms of adhesion strength is critical for energy efficiency in energy-intense industries. Geopolymer-based composites composing of hollow glass microspheres (HGMs), waste fly ash (FA), and metakaolin (MK) were successfully applied on hot (T～300 °C) metal surfaces via spray deposition technique. The effect of Si/Al and Na/Al mole ratios and HGM loading on geopolymer composites' physical, microstructural, thermal, and adhesion strength properties were explored. The best composite composition was obtained when Si/Al mole ratio, Na/Al mole ratio, and HGM loading were 2.5, 1.0, and 10 wt %, respectively. This composition achieved an HGM/geopolymer composite material with low thermal conductivity (k ～ 0.05 W/mK), high adhesion strength (～5.0 MPa), and high stability under immersion in water and vibration environments (particularly exposed to water). The results showed that HGM/geopolymer composites could be used as a thermal insulation material in energy-intense industries.     

The addition effect of hollow glass microsphere on the dispersion behavior and physical properties of polypropylene/clay nanocomposites

Polypropylene (PP) nanocomposites have been widely researched for last decade due to its high mechanical property and multiple usages in various industrial fields from automobile to consumer packaging. Dispersion of nanoclay in polyethylene and PP is the key factor due to their hydrophobic property. Adding surfactant or introducing a polymer with a functional group, and modifying a natural clay with organic ions have been tried to achieve the better dispersion of clay in polymer matrix. In this study, the PP/clay nanocomposite with maleic anhydride grafted PP and hollow glass microspheres (HGMs) at various compositions were prepared and characterized. The addition of HGMs to PP/clay nanocomposites significantly improved the tensile stress at yield point except 7 wt % of HGMs. It is assumed that this could be due to not only the reinforcing effect of HGMs in PP, but the crushing effect of HGMs on the clay resulting in interlayer increase of clay as well. The barrier properties was also found to be improved about 32% max resulting from the better dispersion and presence of HGMs. It could be assumed that the HGMs could act as a ball creating a ball milling crush force to achieve the better dispersion of clay in the polymer and improve nanocomposite performance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47476.     

Oxidation of TiB2 Powders below 900°C

Oxidation studies have been performed on titanium dibor-ide (TiB₂) powders, from room temperature up to 900°C. The studies were performed at low partial pressures of oxygen, at 10 and 0. 05 ppm of O₂ in argon, simulating furnace atmosphere with flowing neutral gas of medium and high purity, and in air. It has been found that titanium borate (TiBO₃) is formed in these processes. It has also been revealed that the oxidation process starts below 400°C and is reversible in this low temperature range from 100° to 400°C.     

Effects of partial and total methane flows on the yield and structural characteristics of MWCNTs produced by CVD

Multi-walled carbon nanotubes (MWCNTs) were produced in a chemical vapor deposition (CVD) process employing methane and argon as hydrocarbon and carrier gas over supported sol-gel Co-Mo/MgO catalysts. A detailed study about the influence of the gas flow of both hydrocarbon and carrier gas on carbon yield, morphology, structure and graphitization degree is presented. Methane partial pressure, methane total flow rate, as well as the flow ratios of methane to argon and methane to hydrogen (reducing gas) were the parameters systematically varied. The results reveal that high MWCNT yields in the produced materials are strongly related to the methane partial pressure and the methane total flow, while a high degree of graphitization is more closely linked to the use of argon gas as inert atmosphere.