共查询到20条相似文献,搜索用时 77 毫秒
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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。 相似文献
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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… 相似文献
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史雪芳 《化学推进剂与高分子材料》1993,(1)
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。 相似文献
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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。 相似文献
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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。 相似文献
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多波段激光防护PMMA材料的制备 总被引:1,自引:0,他引:1
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。 相似文献
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《Ceramics International》2017,43(3):2938-2942
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. 相似文献
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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. 相似文献
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《Ceramics International》2020,46(3):3066-3073
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. 相似文献
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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. 相似文献
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《Ceramics International》2022,48(21):31389-31396
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. 相似文献
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《Journal of the European Ceramic Society》2021,41(13):6548-6558
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. 相似文献