Preparation and characterization of amorphous boron powder with high activity

The amorphous boron powders with high activity were prepared by the high-energy ball milling-combustion synthesis method. The effects of the milling rate and milling time on the crystallinity, microscopic morphology and reactivity of amorphous boron powder were studied. The results show that the crystallinity of amorphous nano-boron powder is only 22.5%, and its purity reaches 92.86%. The high-energy ball milling can significantly refine boron powder particle sizes, whose average particle sizes are smaller than 50 nm, and specific surface areas are of up to 70.03 m2/g. When the transmission electron beam irradiates the samples, they rapidly melt. It can be seen that the monomer amorphous boron size is less than 30 nm from the specimen melting traces, which indicates that the samples have high reactivity.

Preparation of amorphous nano-boron powder with high activity by combustion synthesis

The preparation process of amorphous nanometer boron powders through combustion synthesis was investigated, and the effects of the reactant ratio, the heating agent and the milling rate on the activity and particle size of amorphous boron powders were studied. The results show that the boron powders exist in the form of an amorphous phase which has the crystallinity lower than 30.4%, and the panicle size of boron powder decreases with an increase of the high-energy ball milling rate. The purity of amorphous boron powder is 94.8% and panicle sizes are much smaller than 100 nm when the mass ratio of B2O3/Mg/KClO3 is 100：105：17 and the ball milling time is 20 min with the milling rate of 300 r/min. At the same time, the amorphous boron nano-fibers appear in the boron powders.

Preparation of High Activity Admixture from Steel Slag,Phosphate Slag and Limestone Powder

The problem of low disposal and utilization rate of bulk industrial solid waste needs to be solved.In this paper,a high-activity admixture composed of steel slag-phosphate slag-limestone powder was proposed for most of the solid waste with low activity and a negative impact on concrete workability,combining the characteristics of each solid waste.The paper demonstrates the feasibility and explains the principle of the composite system in terms of water requirement of standard consistency,setting time,workability,and mechanical properties,combined with the composition of the phases,hydration temperature,and microscopic morphology.The results showed that the steel slag:phosphate slag:limestone=5:2:3 gave the highest activity of the composite system,over 92%.Besides,the composite system had no significant effect on water demand and setting time compared to cement,and it could significantly increase the 7 and 28 d activity of the system.The composite system delayed the exothermic hydration of the cement and reduced the exothermic heat but had no effect on the hydration products.Therefore,the research in this paper dramatically improved the solid waste dissipation in concrete,reduced the amount of cement in concrete and positively responded to the national slogan of carbon neutral and peaking.

Preparation of Nano-sized Zirconium Carbide Powders through a Novel Active Dilution Self-propagating High Temperature Synthesis Method

High quality nano-sized zirconium carbide （ZrC） powders were successfully fabricated via a developed chemical active dilution self-propagating high-temperature synthesis （SHS） method assisted by ball milling pretreatment process using traditional cheap zirconium dioxide powder （ZrO2）, magnesium powder （Mg） and sucrose （C12H22Oll） as raw materials. FSEM, TEM, HRTEM, SAED, XRD, FTIR and Raman, ICP- AES, laser particle size analyzer, oxygen and nitrogen analyzer, carbon/sulfur determinator and TG-DSC were employed for the characterization of the morphology, structure, chemical composition and thermal stability of the as-synthesized ZrC samples. The as-synthesized samples demonstrated high purity, low oxygen content and evenly distributed ZrC nano-powders with an average particle size of 50nm. In addition, the effects of endothermic rate and the possible chemical reaction mechanism were also discussed.

Polyphenol content and antioxidant activity in mulberry powder treated at high temperature

The aim of this study was to investigate changes of polyphenols content and the antioxidant activity of mulberry fruit powder after heating at high temperature.The mulberry fruit powder was heated by baking method at different temperature and time.The DPPH scavenging ability,the OH^(•-) scavenging ability and the O_(2)^(•-) scavenging ability were used to evaluate the changes in the antioxidant activity of the mulberry fruit powder after the heat treatment.The results showed that 74.87%of the polyphenols in the mulberry powder were lost after heating at 150℃for 5 min,and almost all the polyphenols were lost with the increase of the heating time and temperature.The antioxidant experiment showed that the DPPH scavenging rate,OH^(•-) scavenging rate and O_(2)^(•-) scavenging rate of mulberry fruit powder were 68.90%,39.15%and 14.09%,respectively after treatment at 150℃ for 5 min.Mulberry fruit powder still has some potential to be added to baked goods as a functional ingredient.

Synthesis of High Purity SiC Powder for High-resistivity SiC Single Crystals Growth

High purity silicon carbide （SIC） powder was synthesized in-situ by chemical reaction between silicon and carbon powder. In order to ensure that the impurity concentration of the resulting SiC powder is suitable for high-resistivity SiC single crystal growth, the preparation technology of SiC powder is different from that of SiC ceramic. The influence of the shape and size of carbon particles on the morphology and phase composition of the obtained SiC powder were discussed. The phase composition and morphology of the products were investigated by X-ray diffraction, Raman microspectroscopy and scanning electron microscopy. The results show that the composition of resulting SiC by in-situ synthesis from Si/C mixture strongly depends on the nature of the carbon source, which corresponds to the particle size and shape, as well as the preparation temperature. In the experimental conditions, flake graphite is more suitable for the synthesis of SiC powder than activated carbon because of its relatively smaller particle size and flake shape, which make the conversion more complete. The major phase composition of the full conversion products is β-SiC, with traces of α-SiC. Glow discharge mass spectroscopy measurements indicated that SiC powder synthesized with this chemical reaction method can meet the purity demand for the growth of high-resistivity SiC single crystals.

Oxidation pathway and kinetics of titania slag powders during cooling process in air

The oxidation pathway and kinetics of titania slag powders in air were analyzed using differential scanning calorimetry(DSC)and thermogravimetry(TG).The oxidation pathway of titania slag powder in air was divided into three stages according to their three exothermic peaks and three corresponding mass gain stages indicated by the respective non-isothermal DSC and TG curves.The isothermal oxidation kinetics of high titania slag powders of different sizes were analyzed using the ln-ln analysis method.The results revealed that the entire isothermal oxidation process comprises two stages.The kinetic mechanism of the first stage can be described as f(α) = 1.77(1-α) [-ln (1-α)]^((1.77-1)/1.77),f(α)= 1.97(1-α) [-ln (1-α)]^((1.97-1)/1.97),and f (α) = 1.18(1-α) [-ln (1-α)]^((1.18-1)/1.18).The kinetic mechanism of the second stage for all samples can be described as f (α)=1.5(1-α)^(2/3)[1-(1-α)^(1/3)]^(-1).The activation energies of titania slag powders with different sizes(d_(1)<0.075 mm,0.125 mm<d_(2)<0.150 mm,and 0.425 mm<d_(3)<0.600 mm)for different reaction degrees were calculated.For the given experimental conditions,the rate-controlling step in the first oxidation stage of all the samples is a chemical reaction.The rate-controlling steps of the second oxidation stage are a chemical reaction and internal diffusion(for powders d_(1)<0.075 mm)and internal diffusion(for powders 0.125 mm<d_(2)<0.150 mm and 0.425 mm<d_(3)<0.600 mm).

基于固废源高活性粉体材料的3D打印混凝土

选用固废源高活性粉体材料和P·O 42.5级水泥,辅助石英砂骨料和缓凝型聚羧酸系减水剂、纤维素醚、可分散乳胶粉等辅料制备混凝土3D打印材料并进行性能研究。以3D打印材料凝结时间、胶砂流动度和抗压强度作为评价依据,分析各组分对材料性能的影响,结合极差分析确定最优配合比,采用SEM对3D打印材料1 d水化产物进行表征。优化后制备的3D打印材料凝结时间85 min,初始胶砂流动度190 mm,30 min胶砂流动度180 mm,材料1 d抗压强度28.8 MPa,3 d抗压强度49.6 MPa,28 d抗压强度70.2 MPa。所制备的材料其性能满足混凝土3D打印系统施工需求并能保证打印材料30 min左右仍具有较好的可打印性,该3D打印材料成本约为363.6~437元/t。

石灰石粉在超高性能水泥基材料中的作用机理

采用扫描电镜、X射线衍射以及差热-热重分析技术研究了石灰石粉在超高性能水泥基材料中的作用机理。研究表明,在高温蒸养的条件下,石灰石粉的水化活性及加速水化效应比较明显,水化生成单碳水化碳铝酸钙和三碳水化碳铝酸钙;在配制超高性能水泥基材料时,掺量为10%的石灰石粉对强度的影响较小,可以降低材料成本。

矿山新型充填胶凝材料概述与发展趋势

为了降低胶结充填成本,提高胶结剂对矿山充填特点的适应性,需要研究低成本、高性能的矿山专用充填胶凝材料。介绍了碱激发胶凝材料、高水材料、胶固粉和CH半水磷石膏胶凝材料。举例分析4种新型胶凝材料的特点可知,碱激发胶凝材料极大地降低了胶结剂成本,提高了固废利用率,高水材料和胶固粉明显提高了胶结剂的充填适应性,而CH半水磷石膏胶凝材料则兼顾了前后两者优点,是一种前景广阔的新型充填胶结剂。综合对比不同充填胶凝材料发展现状得出,更加重视充填体早期强度、探索更多固废资源化的可能、充分考虑矿山充填特点和胶凝材料与充填技术协同发展将是矿山胶凝材料今后发展的主要趋势。

大掺量粉煤灰活性粉末混凝土耐久性研究

研究了以大量粉煤灰取代水泥,并掺加硅灰、钢纤维配制的大掺量粉煤灰活性粉末混凝土(HVFRPC)的耐久性。研究结果表明,大掺量粉煤灰活性粉末混凝土具有较小的体积收缩率,抗碳化、抗氯离子渗透、耐硫酸盐浸蚀性优异。

活化铁矿粉技术及其效果评价

随勘探技术发展,高压超高压油气井日益增多,高密度、超高密度钻井液使用也越来越多。室内为配制密度大于2.4 g/cm3的超高密度钻井液,采用铁矿粉作为加重剂,并通过表面活化的原理对铁矿粉进行表面处理,以提高钻井液的固相容纳能力。该活化工艺借鉴了国内外相关产品的技术特点,以优选的表面活性剂为主要活化材料,并添加了无机盐和硅酸盐作为助吸附材料,提高了活化效果。室内实验表明,用活化铁矿粉加重的钻井液体系能保持良好的流变性和悬浮能力,能保证钻进时的正常循环,并且摩阻系数也低于常规铁矿粉加重钻井液。

废胶粉填充改性RHDPE增容研究

研究了废胶粉的活化处理、不同种类相容剂对回收高密度聚乙烯/废胶粉(RHDPE/WRP)共混体系的增容效果。结果表明,WRP活化处理对提高WRP界面活性有效果。不同相容剂对提升共混体系性能的影响不同,其中添加10份马来酸酐接枝聚乙烯(PE-g-MAH)相容剂对提升RHDPE/活化WRP体系整体性能最有效,可使RHDPE/WRP共混材料的拉伸强度从简单共混物的18.8 MPa提高到22.5 MPa,缺口冲击强度从37.5 kJ/m2提高到60.9 kJ/m2;热变形温度从55.8℃提高到63.6℃。

低品位菱镁矿铵盐浸出试验研究

以辽宁海城某低品位菱镁矿为原料,在不同温度和时间条件下进行焙烧,获得高活性轻烧粉。对轻烧粉进行磨矿、筛分和不同种类铵盐浸出试验。结果表明:在浸出反应过程中,NH4+浓度是影响浸出效率的主导因素。NH4+浓度为7.0 mol/L,浸出反应温度75℃,浸出反应1.5 h时,浸出率最高达到83.1%。相同条件下(NH4)2SO4溶液的浸出效率高于NH4Cl。

复掺磁铁矿粉和活性炭粉沥青胶浆高温流变特性研究

复掺磁铁矿粉和活性碳粉制备掺和料沥青胶浆,通过动态剪切流变试验(DSR)和布氏黏度试验,对比研究7组不同复掺比例的沥青胶浆高温流变特性,分析了复掺比例、试验温度和荷载作用频率等对沥青胶浆高温车辙因子、复数剪切模量、相位角和布氏粘度的影响规律。结果表明:活性炭粉在提高复掺沥青胶浆高温稳定性的同时,亦增加其黏度。建议其最佳掺配比例范围为60%~80%。磁铁矿粉与活性碳粉的复掺改性作用对沥青胶浆的相位角影响较小;高温条件下,当磁铁矿粉/活性碳粉复掺比例降低时,沥青胶浆的温度敏感性逐渐减弱。

自蔓延高温合成技术研究与应用的新进展

自蔓延高温合成 (SHS)技术是一门新兴的学科 ,因其独特的优越性而吸引着各国学者进行研究。本文从研究和应用两个方面介绍了SHS的具体特点 ,重点分析了SHS技术在制备粉体、烧结、催化剂、强化致密化、焊接、颜料和涂层等典型的工业化实践应用的新进展 ,并进行了综合比较和系统归纳总结。通过分析 。

高密度活化钨粉低温烧结近全致密化行为

采用物理化学方法制备超细高密度活化钨粉(W-0.1%Ni复合粉末,质量分数),研究球磨时间对活化钨粉形貌及其物理性能的影响,探讨球磨处理对该高密度活化钨粉烧结致密化行为的影响,并与超细纯钨粉末的烧结致密化行为进行对比。结果表明:微量活化元素镍的添加及球磨处理能明显加速钨粉的低温烧结收缩速率,显著促进钨粉的烧结致密化程度;球磨5 h后,活化钨粉在1 600℃下烧结即可达到近全致密化(致密度为99.4%),此外,镍元素的添加和球磨处理也能显著促进钨晶粒的长大。

两段种子分解法制备超细氢氧化铝微粉工艺研究

研究成功了制取非晶质高活性种子的方法,活性晶种能够破坏铝酸纳溶液的稳定性,诱导出一个突然自发产生超细氢氧化铝晶粒的过程。采用两段分解工艺制备了超细氢氧化铝,研究了种子比、温度、精液中苛性Na2O与Al2O3分子比αK的影响。控制分解过程既有次生晶核的生成又要保持一部分晶粒适当长大。超细氢氧化铝产品粒度保持在1.5～2μm范围,产品比表面积4m3/g左右。

微波辐射工艺环保型高强力再生胶配方的研制

由20目的废旧载重轮胎胎冠胶粉与无污染的软化剂、再生剂和偶联剂等研制环保型高强力再生胶的配方,物料经过微波辐射再生,精炼好的胶片表面光洁,质地均匀,适合压延、压出工艺。再生胶的拉伸强度和扯断伸长率能分别达到19.01 MPa和445.80%。

金属铝水解制备高纯氢氧化铝

本文介绍了一种全新的高纯氢氧化铝制备技术。经多极雾化活化设备处理得到的活性铝粉,可在不添加任何化学试剂的条件下与水发生持续水解反应,获得高纯度氢氧化铝粉体。利用XRD,BET,SEM和拉曼光谱、激光粒度仪对水解产物进行性能和结构研究。研究结果表明,活性金属铝粉末的水解历程较为复杂,在反应过程中有多种水解产物生成。水解反应溶液的拉曼光谱结果表明溶液中存在Al(OH)4-阴离子,Al(OH)4-阴离子的出现推动了水解产物的生成。水解产物粒度及颗粒形貌随水解历程发生较大的变化。