物料性质和大小对其在窑内加热升温过程的影响

依据传热原理,建立了物料颗粒在投入窑内加热时升温过程的简化数学模型,用有限差分隐式格式推导了节点方程,并用高斯-赛代尔迭代法进行了编程数值求解。在计算机上模拟研究了物料颗粒在窑内的加热升温过程,探讨了颗粒大小及性质对加热升温过程的影响。研究结果对认识物料在窑内加热升温特性有一定积极作用,也为下一步的深入研究打下了基础。     

Particle Size and Optical Properties of Montmorillonite in Suspension

The light absorption spectra of monoionic montmorillonite suspensions with Li, Na, K, Rb, NH₄, Cs, Mg, Ca and Ba as adsorbed ions were studied in the wavelength range 200–800 mμ. Theoretical analysis of the spectra showed that in the visible range, only scattering is responsible for light intensity attenuation. The scattering was found to depend on the type of adsorbed ion and to increase systematically along the series from Li to Ba. This was attributed to increased particle size of the clay caused by parallel plate condensation to form tactoids. A geometrical model of a montmorillonite tactoid was assumed. The general dependence of the properties of such tactoids, and of their suspensions, on the number of plates per tactoid was formulated. Using the measured values of light absorbance index, and the theoretical model, the relative sizes, measured by the number of plates per tactoid, in the different ionic forms were calculated. The relative sizes thus estimated were found to agree favorably with relative sizes calculated from negative adsorption surface area measurements. A typical peak of specific light absorption was observed at 240–245 mμ, for both the suspensions and their clay-free supernatant solutions. Though the compound responsible for this peak is unidentified yet, its quantity in the various suspensions could be roughly estimated. The quantity was found to be negatively correlated with the relative size of the tactoid. It was concluded that the average particle size of montmorillonite in suspension markedly and systematically depends on the type of adsorbed ion. The implications of this finding are discussed.     

聚四氟乙烯阻水透气滤材的制备及性能研究

以氯化钠作为致孔剂,采用冷压烧结的方法制备了具有阻水透气功能的聚四氟乙烯滤材,通过SEM观察、接触角测量及通透性测试研究了该滤材的表观结构和性能。结果表明:烧结温度和致孔剂用量是影响滤材阻水透气效果的两大因素;当烧结温度为360℃,氯化钠用量为30%时,聚四氟乙烯滤材的透水量为0.22 L/(m~2·h),透气量为7 500 L/(m~2·h)。     

橡胶粒子尺寸对ABS树脂性能的影响

通过乳液聚合制备了橡胶粒子尺寸为64～420 nm的丙烯腈-丁二烯-苯乙烯(ABS)共聚物.然后将其与SAN-T树脂熔融共混制备橡胶质量分数为15%的ABS树脂.研究了橡胶粒子尺寸对ABS树脂力学性能影响和材料内部形态结构.结果表明:随着橡胶粒子尺寸的增加ABS树脂的冲击韧性提高.当橡胶粒子尺寸在320 nm时,拉伸强度达到最大,ABS树脂的综合性能达到最好.粒子尺寸在64～110 nm时,橡胶粒子在基体内部发生团聚,材料发生脆性断裂.当橡胶粒子尺寸在216～420 nm时,材料主要以韧性断裂为主,发生脆韧转变.具有双峰分布ABS-110nm/ABS-275 nm共混物大、小橡胶粒子间发生明显的协同作用.     

Influence of Dose on Particle Size and Optical Properties of Colloidal Platinum Nanoparticles

Attempts to produce colloidal platinum nanoparticles by using steady absorption spectra with various chemical-based reduction methods often resulted in the fast disappearance of the absorption maxima leaving reduced platinum nanoparticles with little information on their optical properties. We synthesized colloidal platinum nanoparticles in an aqueous solution of polyvinyl pyrrolidone by gamma radiolytic reduction method, which produced steady absorption spectra of fully reduced and highly pure platinum nanoparticles free from by-product impurities or reducing agent contamination. The average particle size was found to be in the range of 3.4–5.3 nm and decreased with increasing dose due to the domination of nucleation over ion association in the formation of metal nanoparticles by the gamma radiolytic reduction method. The platinum nanoparticles exhibit optical absorption spectra with two absorption peaks centered at about 216 and 264 nm and the peaks blue shifted to lower wavelengths with decreasing particle size. The absorption spectra of platinum nanoparticles were also calculated using quantum mechanical treatment and coincidently a good agreement was obtained between the calculated and measured absorption peaks at various particle sizes. This indicates that the 216 and 264-nm absorption peaks of platinum nanoparticles conceivably originated from the intra-band transitions of conduction electrons of (n = 5, l = 2) and (n = 6, l = 0) energy states respectively to higher energy states. The absorption energies, i.e., conduction band energies of platinum nanoparticles derived from the absorption peaks increased with increasing dose and decreased with increasing particle size.     

Nonwoven Filter Material

Technology was developed for nonwoven material for filtration of milk. The mathematical dependences of the properties of the nonwoven filter material on the process parameters were obtained. The process parameter were optimized.     

Effects of Injection Pressure on Diesel Engine Particle Physico-Chemical Properties

The effects of injection pressure on diesel particle physical and chemical properties were investigated on a heavy-duty diesel engine. Three injection pressures (600 bar, 800 bar, and 1000 bar) were selected at two engine loads (0.3 MPa BMEP and 0.9 MPa BMEP). The exhaust particle size distribution was measured by a scanning mobility particle sizer (SMPS). Consistent with previous studies, increasing injection pressure effectively removes accumulation mode particles, which results in a significant decrease in particle total mass concentration. The elemental carbon emission factors were then tested through organic carbon/element carbon (OC/EC) analysis. The emitted EC is decreased by 64% and 50% with increasing injection pressure from 600 bar to 1000 bar at the low and high engine loads, respectively. Particle morphology and oxidation reactivity were investigated by means of transmission electron microscope (TEM) imaging and thermogravimetric analysis (TGA) technology, respectively. Smaller primary particles with shorter and flatter graphene layer segments are observed at higher injection pressure conditions, and the particle oxidation reactivity is increased with injection pressure.

Copyright 2014 American Association for Aerosol Research     

反应时间对钽掺杂球形氧化钨性能的影响

以Ta Cl5和Na2WO4为原料,采用水热法在170℃保温6h~48h合成钽掺杂球形氧化钨。利用XRD、SEM等手段对产物进行物相、形貌表征。研究表明:水热反应时间为6h~48h均能获得三斜晶型的氧化钨球,球体尺寸在200nm~350nm之间。对不同反应时间条件下合成的氧化钨球进行紫外-可见光的吸收光谱分析可知,随着反应时间的增加,获得钽掺杂氧化钨样品对光的吸收能力增强,平均禁带宽度为3.72e V。     

Influence of Particle Characteristics on Filter Ripening

Abstract

To investigate the dependence of filter ripening on particle size and surface charge, multiple experiments were conducted under different particle destabilization conditions including pH control, alum, and polymer destabilization. Laboratory‐scale filtration experiments were performed at a filtration velocity of 5 m/h using spherical glass beads with mean diameter of 0.55 mm as collectors. Particle suspensions with a broad size distribution and a 1.7 µm mean particle size were filtered through a 10 cm depth filter column. Better initial solids removal was confirmed under favorable particle and collector conditions (i.e., under smaller surface charge), but better initial particle removal does not necessarily mean better overall particle removal efficiency. It was shown that changes of the particle size distribution (PSD) in the effluent can significantly influence overall particle removal efficiency. Chemical parameters such as zeta potential can be important during the initial stage of filtration, but their importance can decrease over time depending on the specific chemical conditions. The influent PSD and the removal of certain size particles during the initial stage of filtration can significantly influence ripening, which in turn, can influence the overall particle removal efficiency.     

电极材料对高折射钛钡玻璃光学性能的影响

研究了不同材质的材料对钛钡玻璃光学性能的影响,探讨利用电熔工艺制备高钛钡玻璃珠的可行性。结果表明相对于Al_2O_3,SiO_2更易使钛钡玻璃颜色着色。而金属钼能显著降低钛钡玻璃的透过率,在静态试验中明显变黑。而2%含量的SnO_2对钛钡玻璃的颜色影响有限。考虑到实际侵蚀量更低,因此只要熔制工艺控制适当,能实现钛钡玻璃的电熔化。     

氢对非晶氮化硅薄膜键合结构和光学吸收特性的影响

采用对靶磁控反应溅射技术以H2和N2为反应气体在不同氢气流量(15~25 Sccm)条件下制备了氢化非晶氮化硅(a-SiN∶H)薄膜,并利用傅立叶红外透射光谱(FTIR)和紫外-可见透射光谱(UV-VIS)对薄膜的键合结构和光学吸收特性进行了分析。结果表明,氢气流量20Sccm时薄膜中氢的键密度最大,薄膜无序度最减小;薄膜的光学带隙Eg和E04逐渐增大。薄膜原子间键合结构和薄膜有序性的变化可归因于反应溅射过程中氢气的钝化和刻蚀作用。     

煅烧煤系高岭土吸油性能与颗粒形貌关系研究

以山西朔州煤系高岭土为原料,利用三水氟化铝(AlF₃·3H₂O)添加剂能够促进莫来石晶须生长的特性,结合超声破碎处理制备高吸油值煅烧煤系高岭土,随后分析了颗粒形貌对粉体吸油值的影响。通过扫描电子显微镜、X射线衍射仪和比表面积分析仪等表征手段分析了AlF₃·3H₂O提高煅烧煤系高岭土吸油值的作用机理。结果表明:AlF₃·3H₂O的添加能够使煅烧煤系高岭土的颗粒表面产生大量莫来石晶须,颗粒表面产生的亚微米级莫来石晶须可显著提高样品的吸油值;此外对样品进行超声处理可以进一步提高其吸油值,当超声处理时间为45 min时,其吸油值可达到86.14 g/100 g;颗粒的圆形度对粉体的吸油值影响较大,高吸油值煅烧煤系高岭土的圆形度整体比普通煅烧煤系高岭土的圆形度低,且圆形度分布更集中。     

聚醚的种类对丙烯酸酯类聚氨酯材料性能的影响

由聚醚与异氟尔酮二异氰酸酯(IPDI)反应得到端异氰酸酯基聚醚,在二月桂酸二丁基锡(DBTL)催化剂作用下与甲基丙烯酸β羟乙酯(HEMA)反应制备了聚氨酯丙烯酸酯大分子单体,并将其交联固化得到透明的新型高分子材料;讨论了反应温度、反应时间、催化剂等反应条件对大单体合成和聚合物制备的影响。研究采用不同聚醚(PEG400、PEG600、PEG1000、PTMG1000)合成透明聚氨酯,详细讨论了聚醚的种类、分子量、含量对聚合物性能的影响。结果表明:随着聚醚分子量的增加,聚合物的硬度、拉伸强度等性能降低,冲击强度提高;而对光学性能影响不大。     

Effects of Low-Thermal-Budget Treatments on the Porous Si Material Properties

Our interest in porous silicon is due to its potential benefits in crystalline Si solar cells. Besides the use as an anti-reflection coating, the porous layer also acts as a light-diffusor. However major drawbacks are the significant light absorption within the porous layer and both insufficient as well as unstable surface passivating capabilities. The unstable nature of the porous Si is also reflected in the presence of suboxides after storage in ambient. In this work we focus on rapid-thermal-oxidation (RTO) and plasma-nitridation as low-thermal-budget chemical modification techniques in order to obtain a surface layer with a controlled and stable structure and composition. RTO of porous Si converts the material into SiO₂ in conjunction with a drastically decreased porosity. Both a remote- and a direct-plasma nitridation of porous Si are able to incorporate nitrogen uniformly throughout the porous layer while preserving the porous character.     

Influence of Thermodynamic,Material, and Bulk Properties on Electrical Resistivity of Particle Layers

Although the influence of gas humidity and particle size distribution on dust resistivity is well known, the impact of thermic and electric balancing periods on the measurement of dust resistivity is less familiar. The dust resistivity of quartz glass (SiO₂) and Al₂O₃ particle layers was measured and exhibits a non‐ohmic behavior as well as time dependence seen in a similar manner during electret formation. However, constant values of dust resistivity for the test dust were first measured after a rather long balancing period which cannot be explained in whole by adsorption and desorption kinetics of H₂O into the particle layers. Rather, it could be presumed that the thermic and electric balancing periods overlap, whereas the electric balancing periods take a much longer time.     

成分构成对复合自润滑材料摩擦学性能的影响

在MPX-2000摩擦磨损试验机上,用环盘式摩擦副测量了不同成分的金属塑料复合自润滑材料与45#钢在干摩擦条件下的摩擦磨损特性.结果表明:在载荷为200 N,滑动速度为200 r/min时,摩擦因数随聚四氟乙烯(PT-FE)用量的增加而减小,当PTFE体积分数超过20%时,摩擦因数下降趋缓;金属塑料复合自润滑材料的磨损率,随PTFE用量的增加.先减小后增加;当PTFE在PEEK/PTFE共混物中的体积分数为10%～20%时,摩擦学性能最佳.     

铁镍合金粉体尺寸和粒度分布对于其微波吸收性能的影响

采用超声波分级筛分三种不同尺寸和粒度分布铁镍合金粉体,通过网络分析仪测试分析了其在不同掺杂浓度下的电磁参数,采用传输线法拟合对比了两组不同掺杂浓度在2 mm下的三种粉体吸波损耗。研究发现铁镍合金粉体尺寸和粒度分布会对粉体的电磁参数及其吸波特性产生影响,粉体尺寸和粒度分布的降低会导致电参数的增大,吸收峰曲线向低频移动,这对于实际应用选择不同尺寸和粒度分布的吸波粉体具有指导性意义。     

Gamma Rays Effects on the Optical Properties of Cerium-Doped Glasses

Optical systems employed in high-energy environments are subjected to high doses of ionizing radiation and the stability of their optical properties is required to avoid a possible failure of the experiments. Radiation hard glasses are widely used as substrates or windows in high-energy applications, due to their resistance in hostile environments where energetic particles and γ rays are present. In this work, radiation-resistant commercial glass samples were irradiated by ⁶⁰Co γ rays from 50 to 3 × 10⁵ Gy absorbed doses and at three different dose rates. The optical properties of the samples were measured to evaluate the gamma irradiation effects and the damage recovery after the end of irradiation. A dependence on the irradiation dose rates was found.     

木质素复合细菌纤维素材料的制备及其吸油性能研究

为制备低成本且绿色环保的新型吸 油材料，本文以细菌纤维素（BC）为基质，脱碱木质素(DL)为疏水改性剂，通过低温浸渍法制备木质素复合细菌纤维素材料（BC-DL）；考察了原料预处理、反应时间、温度以及物料比等对BC-DL疏水及吸油性能的影响。利用FTIR、XPS、SEM、BET、接触角仪对材料的化学结构及微观形貌进行表征。结果表明，与改性前相比，DL改性后BC的比表面积由33.15 m2/g提升至71.09 m2/g，水接触角由未改性BC的19.5°增大到116.8°。吸油实验结果显示，BC-DL对花生油、柴油、真空泵废油的吸油量（OCA）分别为34.8 g/g、33.7 g/g、34.6 g/g；在经过8次循环后，OCA保留在19.1 g/g、18.3 g/g和18.8 g/g，BC-DL对三种油品均有良好的吸附性能和循环利用性。     

压力过滤罐滤料再生改造

简要介绍了桩西联合站污水压力过滤罐污染滤料的罐外清洗,重复使用的技术。该技术在不影响生产正常运行的情况下,充分利用现有设备进行改造,取得明显的经济效益和社会效益。