汽液相平衡研究进展

概述了近年来汽液相平衡的测定方法:直接法(蒸馏法、静态法、流动法、循环法、泡露点法),间接法(饱和蒸汽压法、沸点仪法)和汽液相平衡计算方法(状态方程法和基团贡献法)的研究现状及其发展趋势,对其进一步的研究做了展望。     

非离子表面活性剂囊泡(niosome)的研究进展——制备、表征及化妆品应用(待续)

3制备方法制备niosome有很多方法,包括薄膜水化(手摇)法(thin film hydration (hand shaking) method)、醚注射法、反相蒸发法、跨膜pH梯度吸药法(trans-membrane pH gradient drug uptake process)、乳液法、脂质注射法、胶束溶液和酶法、鼓泡法(bubble method)、微流化法(microfludization method)、由proniosome形成niosome法、超临界反相蒸发法。     

乳液聚合竞聚率测定技术进展

将近年来测定共聚物的组成方法分为气相色谱法、红外色谱法、氢核磁共振法、元素分析法等4类。综述了Fineman Ross(F-R)法、Kelen Tudos(K-T)法和Yezreielv Brokhina Roskin(YBR)法等3种计算单体竞聚率方法的优缺点,展望了乳液聚合竞聚率研究技术的前景。     

V-P-O催化剂制备方法研究进展

简要介绍了五种V-P-O催化剂的制备方法(传统法、气溶胶法、火焰沉积法、气相法和固态法)和三种耐磨催化剂的制备方法(浸渍法、包容法、嵌入法)。传统法是制备V—P-O催化剂最基本的方法;气溶胶工艺是一种快速干燥制备催化剂的方法;火焰沉积技术是制备纳米级钒磷氧化物的方法之一。     

氟硅酸含量分析方法的选择

1　氟硅酸含量分析方法的比较氟硅酸含量〔w(H2SiF6)〕的测定,有氟氯化铅称量法(PbClF法)、甲基橙指示剂碱标液滴定法(甲橙法)、酚酞指示剂碱标液滴定法(酚酞法)、氟硅酸钾水解碱标液滴定法(K2SiF6法)等多种。(1)　PbClF法的分析原理是,在酸性溶液中H2SiF6与Cl及Pb2+生成氟氯化铅沉淀。反应式为:H2SiF6+14Cl+6Pb2++3H2O6PbClF6↓+8HCl+SiO32氟氯化铅沉淀经过滤、洗涤、烘干、称量,由计算即可求出氟硅酸的含量。该法沉淀过程需水浴保温陈化30min,还要静置过夜(室温下),测定一个样品要一天半时间才能完成,显然生产中不宜采用。(2…     

浅析CO工业制备

羰基合成工业分离提纯CO技术主要有纯氧(富氧)焦炭法、变压吸附法、膜分离法、深冷法、COSORB法,分别简单介绍了这几种方法的原理及流程。     

负载型催化剂中金属分散度的测定

介绍了负载型金属催化剂中金属分散度的四种测定技术,即化学吸附法(Chemisorp)、X射线衍射法(XRD)、透射电镜法(TEM)和X光电子能谱法(XPS)。Chemisorp设备简单、应用普遍、局限性小;TEM具有直观粒子形貌、大小及其分布的优点;XRD用于测定金属粉末粒子的大小,是比较成熟的技术;XPS测定金属分散度可定性指示。并通用于各类催化剂。     

结肠透析液(B液)中钾含量测定方法的比较研究

建立结肠透析液(B液)中钾含量测定方法。采用银量法(法定方法)、四苯硼钠-季胺盐法、四苯硼钠-容量法、紫外-紫外导数光谱法、原子吸收分光光度法(FAAS)及电感耦合等离子体发射光谱法(ICP-AES)测定结肠透析液(B液)中钾的含量,并对六种方法的精密度、线性范围及检出限、加标回收率等做了比较。6种方法测定结果与法定法(银量法)结果一致,误差在允许范围内。FAAS法是测定结肠透析液中钾含量的较优方法。     

涂层耐湿热性测试方法简介

介绍了ASTM标准中4种测试方法(浸渍法、水雾法、100%相对湿度法和冷凝法)测定涂层耐湿热性的原理、仪器设备、测试步骤和结果表示,并给出了4种测试方法的差异。     

陕北低变质煤分质综合利用前景展望

煤制烯烃技术的发展使得煤基乙烯法PVC工艺成为一种选择,通过对不同工艺全流程碳排放量(直接碳排放+间接碳排放)进行计算分析,认为相对于煤基乙烯法PVC(纯锅炉模式)生产工艺,电石法和煤基乙烯法PVC(锅炉+燃气轮机模式)的碳排放较低,而由于后者不存在汞污染问题,从CO2减排、能源转化效率、成本和清洁化生产等综合角度来讲具有一定的优势.     

LMS-24激光衍射粒度分布测试仪及其应用

介绍了LMS-24激光衍射粒度分布测试仪的构造、测量原理和特点,指出了检测过程中应注意的几个问题,包括试料取样、试料农度、分散剂浓度、分散方式和分散时间对测试结果的影响等。     

多波段激光防护PMMA材料的制备

以聚甲基丙烯酸甲酯(PMMA)为基材．在基材中加入防激光吸收剂IR530、IR1065,制备了能有效吸收488nm、514nm、530nm、1060nm等多个波长激光的PMMA材料。通过实验研究确定了防激光吸收剂IR530、IR1065的加入量和激光防护PMMA材料的制备工艺参数。结果表明,多波段激光防护PMMA材料在488nm、514nm、530nm处的透过率为0．01％,在1060nm处的透过率为0．02％,具有良好的激光防护性能。同时防激光吸收剂的加入对材料的冲击强度影响很小。     

Effect of laser scanning speed on geometrical features of Nd:YAG laser machined holes in thin silicon nitride substrate

0.5 mm thick Silicon nitride (Si₃N₄) substrates with MgO-Y₂O₃ additives were employed for hole machining study with a Nd:YAG two-dimensional laser machining (cutting) system. The effects of laser scanning speed on features of the machined holes such as hole diameter, hole circularity, taper angle, heat affected zone (HAZ), recast layer, and micro-cracks were studied. The results show that the diameters at the front side are larger than the back side for all holes machined at different spot scanning speed. The taper angle of the machined holes decreases, while the hole circularity increases with the increase of the spot scanning speed. In addition, the heat-affected-zone (HAZ) was observed clearly around the back side of drilled holes, whose area decreases with the increase of the laser spot scanning speed. The result shows that the HAZ is the largest when the laser scanning speed is 20 mm/min. Nevertheless, the machined hole did not completely cross through the thickness of the substrate when the laser scanning speed was 60 mm/min. To obtain holes with relatively good quality, laser scanning speed should be controlled between 30 mm/min and 50 mm/min.     

Improved direct bonding method of Nd:YVO4 and YVO4 laser crystals

We succeeded in the fabrication of bonded laser crystals composed of a neodymium-doped YVO₄ laser crystal (Nd:YVO₄) and its host crystals YVO₄ by a newly developed dry etching technique using an argon ion beam. The optical distortion caused by the bonded interface of size 5 mm × 6 mm was estimated to be 0.05λ at 633 nm. From the comparison of laser performance pumped by a laser diode, the bonded crystals could increase the laser output power by nearly twice that of the non-bonded crystals with the same degree of polarization of 99.2%. To analyze the mechanism of the enhanced reduction of the thermal load in the bonded crystals, numerical simulations with a finite-element method were also performed.     

Comparison thermochemical and thermophysical performances analysis in laser processing by dynamic heat-matter diffusion coupling simulation and corresponding experiment validation

The laser-matter interaction contains complex thermophysical and thermochemical responses. The variation of energy and composition happen in thermophysical and thermochemical process will totally change the interaction behaviors. In order to obtain an accurate mechanism and promote the understanding of laser-matter interaction, all thermophysical and thermochemical responses, especially the thermochemical part, should be considered and investigated. In this study, a coupled heat-matter diffusion model based on thermodynamic chemical equilibrium finite-element method and thermochemical ablation theory was established. The materials with complex reaction enthalpy change in high temperature environment were chosen to validate the model. The results show that this model is accurate, as the maximum error of back-surface temperature response is just 4.0% between experimental and calculation values. The detailed variations of composition, temperature and optical reflection were obtained and analyzed, which is in good agreement with the experiment. This coupled heat-matter diffusion model including all thermophysical and thermochemical response has the great potential in nearly all laser-matter interaction involved application.     

激光闪射法测试氮化硅结合碳化硅材料导热系数的研究

激光闪射法在材料导热系数的测量方面已得到广泛研究和应用。利用激光闪射法测试了氮化硅结合碳化硅材料的导热系数,分析了影响结果准确性的因素,并提出了相应措施。     

激光闪射法测量耐火材料的热物理性能

介绍了应用激光闪射法测量耐火材料比热容、热扩散系数以及导热系数等热物理性能的原理,列举应用实例说明了测试方法,并且讨论了影响实验数据准确性的因素。     

三维激光全息打印机的研制与发展

最近,关于数字激光全息技术、数字衍射光学元件的制造技术与设备的研究比较活跃.激光全息打印是在数控激光全息技术薄膜材料上打印出富有立体感的、动态的、彩色的文字和图像,其中,三维激光全息打印机是比较新的一个产品.本文正是对三维激光全息打印机的研制和发展做出探讨,了解这项新技术.     

Laser stealth and laser protection properties of oxide-carbide coatings prepared by atmospheric plasma spraying

With the development of laser technology, laser-related materials have been widely studied. Both laser stealth coatings and laser protective coatings are currently the focus of attention. However, less research has been done on laser stealth and protective integrated coatings. In this paper, plasma-sprayed Y₂O₃–Ti₃AlC₂ coatings were prepared with low-power (LP) and high-power (HP) parameters, and their laser stealth and laser protection properties were characterized. The LP coating and HP coating appeared to have lower reflectivity at 1064 nm because a low-reflectivity second phase and many loose flocs on the surface are introduced, which indicates excellent laser stealth performance. When irradiated by a laser, the LP coating exhibited excellent laser protection ability, and its reflectivity increased after irradiation because Ti₃AlC₂ oxidized and decomposed and densely arranged small particles formed on the surface. The LP coating perfectly protected the 500-W laser irradiation for 20 s. In addition, the laser damage threshold of the LP coating was 5.599 s at 1000-W laser irradiation, which indicates that the LP Y₂O₃–Ti₃AlC₂ coating is a potential material with laser stealth and laser protection integration.     

Effects of reflectivity on laser-ablation resistance of the laser-cladding repaired Nd2O3 modified SiO2 coatings on C/C composites

To repair the damaged SiC coated C/C composites, a double-layer coating including a SiO₂-Nd₂O₃ external layer (∼60 μm) and a Si-SiC inner layer (∼240 μm) was prepared by a slurry-based laser cladding technique, and the laser-ablation tests under two heat fluxes (23.89/39.81 MW m⁻²) were performed. The spectrophotometer, X-ray diffraction, scanning electron microscopy and 3D profilometer were used for characterization. For avoiding the secondary damage of laser-ablation, the laser-reflection of the repaired area was enhanced, which was conducive to the mitigation of mass and linear ablation. Combined with Finite Element Analysis, by raising the reflectivity, the surface and back temperature of samples could be reduced greatly by 1224 K and 983 K respectively, and plenty of ablation reactions could be avoided. Therefore, the SiO₂-Nd₂O₃ coating possessed an excellent laser-ablation resistance and protected the C/C substrates from thermal damage and oxidation effectively.