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利用等离子喷涂技术在医用Ti合金表面制备了TiO_2、CaF_2-TiO_2和Ag2O-CaF2-TiO_2涂层。对涂层的微观结构进行表征,并对涂层表面粗糙度、接触角和耐腐蚀性进行测试。通过离子释放实验考察复合涂层中Ca~(2+)、F~–和Ag~+的释放特性。利用Ca、P比为常规模拟体液2倍的溶液(2SBF)中浸泡实验评价复合涂层的体外矿化能力。利用金黄色葡萄球菌和大肠杆菌来评价涂层的抗菌性能。结果表明:等离子喷涂TiO_2涂层主要由金红石和少量锐钛矿相组成,而在CaF_2-TiO_2和Ag_2O-CaF_2-TiO_2涂层中均出现了Ca_2Ti_2O_6固溶体;TiO_2涂层的表面粗糙度随着CaF_2和Ag_2O的加入而变大,其亲水性也得到改善。CaF_2和Ag_2O的掺杂显著提高了TiO_2涂层的耐腐蚀性;3种涂层均具有诱导磷灰石生成的能力,展现了良好的体外生物矿化能力。Ag掺杂极大提高了Ag_2O-CaF_2-TiO_2涂层的抗菌性能。 相似文献
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本文以γ-Al2O3为载体,H2SO4溶液为浸渍液制备了SO2-4/Al2O3超强酸催化剂.用正交实验的方法对SO2-4/Al2O3超强酸的制备条件进行了考察,找到了决定SO2-4/Al2O3酸性质的主要因素. 相似文献
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回顾了Y2O3、Sm2O3和Gd2O3掺杂的CeO2夹层(YDC、SDC和GDC)在Y2O3稳定的ZrO2(YSZ)基SOFC中的发展历史以及目前发展状况,分析了粉体的制备方法、夹层的沉积工艺、陶瓷烧结工艺对CeO2夹层性能的影响。从材料的化学相容性和热膨胀匹配等方面阐述了制备CeO2夹层的目的,对CeO2夹层大大提高电极性能进行了详尽的机理分析。指明了CeO2夹层对SOFC的重要作用和发展前景。 相似文献
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Li2ZrO3能够在高温下吸附CO2,并且其吸附效率高、速度快、稳定性好且能够重复利用。作者对近年来有关Li2ZrO3材料吸附CO2的研究进行了分析,比较了Li2ZrO3的各种合成方法的优缺点,介绍了Li2ZrO3吸附CO2的反应机理,分析了影响Li2ZrO3吸附CO2的吸附量及速率的各种因素,并对高温下吸附CO2的Li2ZrO3材料的前景进行了展望。 相似文献
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以嵌段聚合物P123为模板,ZrOCl2·8H2O和Ce(NO3)3·6H2O为原料,采用水热法合成了CeO2-ZrO2纳米材料,经400℃焙烧后利用油酸对其进行表面改性,然后将其均匀分散于环氧树脂中,制备了CeO2-ZrO2-环氧树脂杂化材料.采用X射线衍射(XRD)及氮气吸/脱附曲线研究了焙烧后的纳米CeO2-ZrO2材料.分析了油酸改性后CeO2-ZrO2介孔材料的红外光谱(FT-IR)、透射电镜(TEM)照片及其与水、CH2I2的接触角,探讨了油酸的改性机理.通过热重-差示扫描量热法(TG-DSC)表征了CeO2-ZrO2-环氧树脂杂化材料的热稳定性,测试了涂膜的性能.结果表明,无机介孔材料CeO2-ZrO2的平均孔径为5.47 nm,比表面积达117.81 m2/g.经油酸改性后,CeO2-ZrO2的亲油性能得到改善,与CH2I2的接触角为32.6°,油酸改性机制包括物理吸附作用和化学键合作用.所制备的CeO2-ZrO2-环氧树脂杂化材料的玻璃化转变温度为376℃,涂膜的各项性能得到有效改善. 相似文献
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在简要介绍木聚糖的结构特点及反应性的基础上,对木聚糖的醚化、酯化、氧化、交联、复合等化学修饰及其衍生物的合成研究现状、应用领域及发展趋势进行了重点评述。从合成路线、特征结构、非常规木聚糖衍生物、物理化学性质、生物活性、构效关系等方面依次对不同类型的修饰产物即木聚糖衍生物进行了分类介绍。此外,还简要叙述了木聚糖的功能化修饰如木聚糖微粒子和纳米粒子、聚合物磁性粒子的制备原理与工艺进展。指出了木聚糖及其衍生物在新领域的应用和今后的研究方向。 相似文献
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概述了纳米分子筛膜研究及其应用的现状。介绍了纳米分子筛膜的制备方法如原位水热合成法、微波辐射合成法、预植晶种前驱体二次合成法等,以及纳米分子筛膜的一些表征方法如XRD、SEM、FT-IR、^29Si MAS NMR等,并对各种方法的优缺点进行了比较。最后为纳米分子筛膜研究提出了新的方法。 相似文献
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当用腐植酸(HA)生产有机无机肥时,并非任何腐植酸均可用,如要保证其刺激作物生长和改良土壤等作用,对腐植酸的速效成分黄腐酸(FA)和棕腐酸(HyA)的含量、盐基交换量、酚羟基含量均有一定要求。根据国外和企业10多年的研究成果,讨论了肥料用腐植酸选用的标准。 相似文献
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The chemical or electrochemical oxidation of phenylenediamines in acidic aqueous media yields the corresponding oligomers or polymers. Their structures and properties are discussed in relation to a closely-related conducting polymer, polyaniline. Depending on the reaction conditions, polyphenylenediamines are produced as powders, colloidal dispersions, thin films, or composites. In contrast to polyaniline, polyphenylenediamines are rated as non-conductors and their conductivities are low. Similarly to polyaniline, these polymers display a salt–base transition and they are redox-active. They act as reductants of noble-metal compounds to the corresponding metals or as precursors in the carbonization to nitrogen-rich carbons. Applications proposed in the literature are outlined; they include the corrosion protection of metals, catalysis, electrorheology, sensors, energy-conversion devices, electrochromism, noble-metal recovery, and water treatment. 相似文献
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Taste and melting behavior are important quality criteria for chocolate. Beyond these, the gloss, snap, and texture are relevant. Different process parameters influence the gloss as well as other criteria such as shell life and fat bloom resistance. In this work, a method to measure the gloss of chocolate is introduced and adapted to small chocolate articles. With this, the gloss could be measured reproducibly. Different process parameters are varied and the gloss of the chocolate is determined. Various methods to improve the gloss are suggested and evaluated. 相似文献
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Structural features of several coals of different ranks are compared using an adaptation of the transalkylation reaction. In the present application of this method, trifluoromethanesulphonic acid is used as catalyst and toluene is used in excess as acceptor and solvent. The process can be visualized as a disproportionation reaction in which intermolecular alkyl transfers occur. Under the influence of the acid catalyst, aryl-alkyl bonds in coal are cleaved and alkyl-aryl bonds are formed with the excess toluene solvent. Thus, a large number of substituted toluene derivatives are formed by transfer of groups from coal. Concentrations of ≈ 20 substituent groups and connecting groups are estimated and compared for a range of coals and numerous other compounds are present in small amounts. These compounds are tabulated for two coals and the possible significance and origin of some of them are discussed. The mechanism of the transalkylation reaction as it applies to coal and the reactions of a limited number of relevant model systems are also discussed. 相似文献
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The results of studies on mercury capillary coulometers containing acidified electrolyte solutions (fluoroborate or perchlorate) or neutral solutions are presented. The effects of the solution composition on the coulometer properties such as internal resistance, current yield, and electrochemical stability are discussed. It has been shown that the solutions of mercury salts which contain fluoroboric or perchloric acid are more advantageous for use as mercury coulometer electrolytes than the iodide solutions used hitherto.The mercury capillary coulometers which are discussed here are widely used as electrochemical integrators and as the working time meters of electrical instruments in laboratories and in industry. 相似文献