铝粉氧化对端羟基聚丁二烯界面吸附影响的分子模拟

为研究铝粉氧化对丁羟推进剂黏合剂界面吸附的影响,采用分子动力学方法和COMPASS力场,分别对端羟基聚丁二烯(HTPB)在Al和Al_2O_3不同晶面吸附进行了模拟计算,求得界面吸附能和静态力学性能(弹性系数、模量和泊松比),结合吸附能和径向分布函数揭示了界面相互作用本质.模拟结果表明,采用HTPB包覆后的Al和Al_2O_3刚度降低,弹性增强;HTPB在Al_2O_3的晶面吸附能远高于在Al晶面,HTPB与Al晶面只存在范德华力作用,而在Al_2O_3的界面吸附主要由静电作用引起.     

提高IPDI体系丁羟推进剂伸长率的研究

以7 MPa下动态燃速为15.6 mm/s和含能固体质量分数为88%的丁羟(HTPB)推进剂配方为基础,研究了氧化剂粒度级配、键合剂种类、扩链剂种类对异佛尔酮异氰酸酯(IPDI)体系HTPB推进剂伸长率的影响。结果表明,相对于T3/MAPO键合剂体系,采用新型T3/A4组合键合剂和扩链剂M1时,可显著提高推进剂伸长率。     

阴离子对Mg(OH)_2晶体生长及形貌的影响机理

以轻烧粉、氯化铵、硝酸铵、乙酸铵、硫酸铵为原料,氨气为沉淀剂,采用氨循环法制备氢氧化镁晶体,并通过扫描电镜(SEM)、X射线衍射(XRD)对其进行表征分析。采用Materials Studio分子模拟软件中的CASTEP模块,计算了Cl~-、NO_3~-、CH_3COO~-对氢氧化镁晶体(001)、(101)晶面生长的影响。结果表明,采用不同的镁盐得到不同形貌的氢氧化镁晶体阴离子电负性越大,对晶体形貌影响越小;Mg(OH)_2晶体的(001)、(101)晶面能量与布居数分析表明,Cl~-、NO_3~-、CH_3COO~-使晶体的(001)、(101)面的表面能增大、Fermi能级减小,阴离子与(001)、(101)晶面之间形成新的具有微弱共价性的离子键,影响晶体晶面的生长。理论计算较好地解释了不同形貌的氢氧化镁晶体的形成原因。     

多组分气体在JOB-9003炸药表面吸附的动力学模拟

为研究多组分气体(CO2、H2O、HCHO、HCN、N2、O2)在JOB-9003炸药(1 0 0)、(0 1 0)、(0 0 1)晶面的吸附机理以及对炸药力学性能和感度的影响,用MS软件构建炸药模型,采用分子动力学(MD)方法得到气体在炸药表面的吸附量和吸附结构,分析了吸附后气体分子与JOB-9003表面分子的径向分布函数,计算了吸附前后引发键的键长分布和炸药体系的弹性系数。结果表明,(1 0 0)晶面的吸附能力最强;多组分气体在晶体表面发生竞争吸附,吸附量由多到少依次为H2O、HCN、CO2、N2、O2、HCHO,这主要与气体分子与炸药表面分子间形成的氢键、分子的极性、气体分子的体积有关;JOB-9003炸药表面吸附的多组分气体使炸药的撞击感度和热感度升高;吸附后炸药的韧性减弱,刚性降低,力学性能变差。     

FOX-7结晶形貌的分子动力学模拟

基于1,1-二氨基-2,2-二硝基乙烯(FOX-7)的晶胞参数,通过修正Dreiding力场得到了适用于FOX-7分子模拟的Dreiding-FOX-7力场;采用Growth Morphology方法模拟计算了FOX-7在真空中的晶体形貌,得到形态学上的重要晶面及附着能参数;构建了FOX-7重要晶面和H_2O/N,N-二甲基甲酰胺、环己酮的吸附模型;利用分子动力学方法计算出溶剂分子与各晶面的吸附能及各晶面的修正附着能;预测了FOX-7在溶剂中的结晶形貌,并与文献结果进行了对比。讨论了氢键的成键强度对晶体形貌的影响。结果表明,FOX-7在H2O/N,N-二甲基甲酰胺中(0 1 1)、(1 0-1)和(1 0 1)晶面为主要生长面,结晶形态为长方体块状;在环已酮中(0 1 1)和(1 0-1)晶面为主要生长面,结晶形态为长棱柱状,与文献结果一致。     

2-硝亚胺基-5-硝基-六氢化-1,3,5-三嗪的晶体形貌预测

利用Materials studio 5.0软件包中的Morphology模块所含的BFDH、Growth Morphology和Equilibrium Morphology三种方法计算了2-硝亚胺基-5-硝基-六氢化-1,3,5-三嗪的晶体形貌,得到了特定的晶面的面积、表面能、附着能及晶面的相对生长速率参数,确定了形态学上重要的生长晶面。各晶面的结构分析表明,(011)和(021)为强极性晶面,(110)、(200)为极性晶面,(001)和(20-1)为弱极性晶面。据此可以预测,在强极性的质子溶剂中,(011)和(021)为形态学上的重要晶面,(110)、(200)、(001)和(20-1)晶面的显露可能增加。在非极性溶剂中,情况可能相反。     

CaSO4表面吸附CH2O2机理的密度泛函研究

基于密度泛函理论的第一性原理优化了CaSO4 (100),(010)和(110)晶面结构,计算了晶面与CH2O2反应吸附能,得出(010)晶面能量最低,吸附最为稳定,发生了化学吸附.通过对CH2O2吸附方式的假设和计算,发现最佳吸附方式为CH2O2分子C=O结构中的氧原子被晶面(010)上的钙原子的垂直吸附,且为化学吸附.吸附机理主要表现为CH2O2中羧基的O原子的2p轨道和H原子1s轨道中的电子向晶体表面(010)上Ca原子的3d轨道发生了转移,从而形成杂化轨道.     

Al2O3含量对钠钙硅玻璃析晶行为的影响

研究了具有高结晶度的20Na2O-29CaO-51SiO2(wt％)玻璃中引入Al2O3后的流变和析晶行为,着重研究了Al2O3含量的增加对成核位置和晶体种类的影响.结果 表明:随着Al2O3的引入,玻璃的粘度逐渐增大,玻璃转变温度和析晶温度也相应地提高;同时粘滞流动活化能明显增大,即晶体形成离子的可移动性降低;另外,Al2O3的引入也导致玻璃由体析晶向表面析晶转变.IR光谱表明,在该体系玻璃中Al3主要以[AlO4]四面体存在,其他低场强阳离子(如Na+和Ca2)对其进行电荷补偿,这导致玻璃中总的非桥氧含量降低,换句话说,玻璃的网络联接程度因Al2O3的引入而增强,离子的体扩散被抑制,因而导致表面析晶.     

Al2O3-SiC系制品中添加物α-Cr2O3的行为

以电熔刚玉和SiC为基料的制品中添加适量亚微米级的绿铬(α-Cr2O3)时,烧成过程中α-Cr2O3生长到1～5 μm,并与刚玉表面接触区发生互扩散行为.SiC在氧化层中氧化并形成玻璃纤维,使氧化层的组分变为Al2O3-Cr2O3-SiO2系.所形成的高硅质液相能促进(Al2-x,Crx)O3固溶体析晶,晶体呈较大的六方柱状自形晶,长度达5～20 μm,长径比(a)为5～10.但此液相中不含Cr2O3.     

聚乙二醇在硅酸二钙表面吸附的分子动力学模拟

采用分子动力学模拟研究了在真空和水溶液环境下聚乙二醇在β-2CaO·SiO₂表面吸附的规律及其机理。在真空环境下聚乙二醇与β-2CaO·SiO₂不同晶面的吸附强弱顺序依次为:(110)>(010)>(011)>(001)≈(101)>(100);而在水溶液环境下其吸附强弱顺序为:(010)≈(110)≈(001)>(011)>(101)>(100)。真空和水溶液环境下在343～363 K时温度对聚乙二醇与β-2CaO·SiO₂(110)晶面相互作用时的单位面积吸附能影响不大,但当在聚合物链节数较小时单位面积吸附能随链节数的增加而明显增加。在水溶液的环境中,分别构造了β-2CaO·SiO₂和聚乙二醇与水分子的径向分布函数,水分子与聚合物、β-2CaO·SiO₂表面之间都存在吸附能,由于水分子较小,其对聚合物与晶面的吸附产生排斥作用,导致聚合物在水环境中与硅酸二钙晶体吸附能降低。     

铝型材仿不锈钢电解着色工艺

采用二步电解着色法在铝型材上获得色泽均匀的仿不锈钢色，性能测试结果表明该着色膜具有良好的耐磨耐蚀性。     

Al2O歧化法制备微细Al2O3/Al复合粉体

真空条件下,以Al2O3和Al为原料,通过Al2O歧化法制备微细Al2O3/Al复合粉体.XRD和SEM分析表明:在反应温度为1200～1400℃时,随着温度的升高,粉体中氧化铝含量升高;冷凝温度约为550～750℃时,复合粉体中的氧化铝包括稳定晶型和不稳定晶型;冷凝温度约为1100～1300℃时,复合粉体中的氧化铝全部为稳定晶型;冷凝温度约为550～650℃时,复合粉体的平均粒径小于0.5μm;冷凝温度约为750℃时,铝熔化、微粒团聚;冷凝温度约为1100～1200℃时,铝形成铝珠,氧化铝为不规则状、平均粒径小于2μm;冷凝温度约为1300℃时,氧化铝为片状.因此,通过选取合适的反应温度、冷凝温度,可以控制Al2O3/Al复合粉体中氧化铝的含量、晶型和粒径.     

Combustion of Al–Al2O3 mixtures in air

An experimental study on the aluminum oxynitride and aluminum nitride formation by combustion of mixtures of micron-sized aluminum powder (average particle diameter a_s ∼9.0 μm) and alumina nanopowder (a_s ∼0.05 μm) of the fixed mass (∼10 g) and different mass ratios (Al/γ-Al₂O₃ = 0.1–19.0) in air is reported. The formation of aluminum oxynitride (Al₃O₃N) and aluminum nitride during the combustion of powdery aluminum-based mixtures in air is discussed in this study. The combustion synthesis of Al₃O₃N and AlN was carried out in self-sustaining way. XPS-FESEM, XRD and chemical analysis were executed on final products of synthesis. The combustion process was also recorded by a video-camera. It was found that powdery mixtures, ignited by local heating, burned in one- or two-stage self-propagating regime. The combustion regime is different for different initial mass ratios Al/γ-Al₂O₃ and mainly depends on the content of fuel (aluminum powder) in mixture.     

Electrochemical analysis of zincate treatments for Al and Al alloy films

Electrochemical behavior of Al and Al alloy films in zincate solution was investigated to elucidate the effect of the zincate pretreatment for electroless NiP deposition, which is used for under bump metallization for LSI interconnects. The immersion potential for AlCu and AlSiCu, immediately reached to constant, which was almost equal potential to zinc reference electrode. The corrosion current for the AlCu and AlSiCu films was larger than that of the Al and AlSi films in the zincate solution. It was also confirmed that the deposited Zn at the surface of AlCu and AlSiCu films possessed smaller grain size and larger amount of nucleation, resulted in the formation of flat NiP films.     

铝材化学氧化

近年来随着我国电子通讯工业的发展 ,铝及其合金的表面加工量也随之增加 ,铝材产品需要进行化学氧化 (其中很多为导电氧化 )。同时对质量要求也越来越高。我们想通过近三年来在铝化学氧化中的情况和生产经验作一个总结 ,供电镀界同仁互相探讨 ,共同提高。众所周知 ,铝化学氧化是指在一定的温度下 ,使铝表面与溶液通过化学作用 ,形成一层致密氧化膜。化学氧化按其溶液的性质又可分为碱性和酸性两类。我厂采用酸性氧化液进行化学氧化。1　工艺流程化学除油碱腐蚀 (去氧化皮 )清洗双酸出光清洗化学氧化清洗浸热水 (5 0～ 6 0℃ )冷风或热风吹干…     

Effect of cryolite on formation of Al2O3/Al composites produced by oxidation of molten Al–Mg alloy

Abstract

The oxidation of molten Al–5 wt-%Mg and Al–5 wt-%Mg–0·5 wt-%cryolite (Na₃AlF₆) has been investigated by carrying out crucible corrosion tests under thermal gradient conditions. Two morphologies of Al₂O₃/Al composite were observed: ‘large balls’ in the absence of cryolite; and small mushrooms in the presence of this salt. Microstructural analysis and thermogravimetric measurements were also carried out to study the effect of cryolite on the oxidation mechanism. The results showed that both composite morphologies are the result of the same directed metal oxidation (DIMOX) process (DIMOX is a trademark of Lanxide Corporation, Newark, DE). Thermogravimetric analysis also confirmed that two morphologies formed under different oxidation kinetic conditions.     

Al2O3/Al复合材料的制备及性能研究

本文采用液相法和热压烧结制备出Al203／Al复合材料,并利用DSC／TG、SEM、显维硬度计及万能试验机测试研究了复合材料的热学性能、微观结构及力学性能。结果表明,引入Al后复合陶瓷的断裂韧性有显著提高。     

Electrochemical Behaviour of Al, Al—In and Al–Ga–In Alloys in Chloride Solutions Containing Zinc Ions

The electrochemical behaviour of Al, Al—In and Al–Ga–In alloys in 0.6 m NaCl solutions with and without Zn²⁺ was investigated. The study was performed by means of open circuit potential, potentiodynamic polarization, potentiostatic current-time and electrochemical impedance spectroscopy measurements as well as by SEM-EDAX examination. It was found that the Al—In alloy exhibits the highest negative open circuit potential in 0.6 m NaCl and the corrosion resistance of the tested electrodes decreases in the following order: Al > Al–Ga–In > Al—In. The greater activity of the Al—In alloy was interpreted on the basis of the autocatalytic attack by indium. The potentiostatic current–time measurements in Zn²⁺ containing electrolyte at potentials above the pitting potential revealed that Zn²⁺ has an insignificant influence on the Al electrode, while it enhances the corrosion of the Al–Ga–In alloy and improves the attack morphology of the Al—In alloy. Furthermore, the impedance spectra recorded under open circuit conditions showed a decrease in the polarization resistance of Al—In and Al–Ga–In alloys in presence of Zn²⁺ indicating the activating effect of Zn²⁺ ions.     

铝青铜零件的钝化

1　概述铜及铜合金具有良好的传热、导电、压延等物理和机械性能 ,因而在仪器、仪表和电气工业中被广泛使用 ,尤以黄铜、青铜的使用更胜一筹 ,但铜及铜合金在空气中 ,特别在潮湿和加热的条件下 ,易氧化腐蚀 ,采用钝化提高其耐蚀性。工艺配方为 :重铬酸钠 ,ｇ Ｌ 10 0～ 15 0硫　　酸 ,ｍｌ Ｌ 2～ 3氯化钠 ,ｇ Ｌ 5～ 10Ｔ室温ｔ,ｓ 3～ 10该配方对铜和黄铜零件较适合 ,对于铝青铜零件来讲 ,形成的钝化膜耐蚀性差。经过试验 ,最终确定了适合于铝青铜零件的彩色钝化工艺。2　试验2 .1　试样试样采用生产过程中的铝青铜零件 ,经前处理后 ,分别…     

Preparation of Pd/Al2O3/Al catalysts for CO removal

Aluminum was carefully anodized, then palladium salts were supported on its A1₂O₃ surface layer by ion-exchange. CO 3.76 vol% contained in the air can be eliminated at around 200 °C. Both anodization conditions and the nature of the precursor solutions affect catalyst nature, particularly the pH value of the precursor solutions. The pH value of the solution suitable for supporting active components is 5–6. Palladium, which is present as Pd²⁺ and Pd⁴⁺ after calcination,distributes uniformly on the support surface which had a honeycomb structure.