用磷矿石真空制备黄磷的热力学研究

引入“物质吉布斯自由能函数法”讨论在不同压力下，磷酸钙、二氧化硅与还原剂碳的反应生成黄磷的热力学条件。研究表明在常压下反应在1460K以上发生；真空条件下，压力降到60～6Pa时，反应在1066～984K时就能进行，比常压下降低了446～476K。真空下磷矿石制备黄磷的热力学研究为工艺实验研究提供理论依据。     

真空下生成AlF2的热力学研究

利用铝的低价氟化物（AlF2）在高温下存在，低温下不稳定且容易分解而得到金属铝的特性，从热力学角度引入：“物质吉布斯自由能函数法”讨论在不同压力下，氧化铝、三氟化铝与还原剂碳的反应生成低价氟化物（AlF2）的条件。研究表明在常压下反应在1820K以上发生。而在真空度（即残压）为20000～20Pa时，反应在1683～1345K时就能进行，比常压下降低了137～475℃，为真空下铝的低价卤化物歧化分解炼铝提供热力学理论依据。     

低价硫化物法直接提取铝的热力学研究

本文利用铝的低价硫化物（AlS）在高温下存在，低温下不稳定容易分解得到金属铝的特性，从热力学角度引入“物质吉布斯自由能函数法”讨论在不同压力下，氧化铝、硫化亚铁与还原剂碳的反应生成低价硫化物（AlS）的条件。研究表明在常压下反应在2480K以上发生；而在真空度（即残压）为300Pa-15Pa时，反应在1800K-1610K时就能进行，比常压下降低了680K-870K，同时用氧化铝、硫化亚铁与还原剂碳在真空炉内试验，验证了理论研究的正确性。为生产工艺的研究提供了热力学理论依据和试验基础。     

真空下用磷矿石无渣工艺制备磷的热力学研究

本文应用"物质吉布斯自由能函数法"讨论标准压力和不同真空条件下由磷酸钙和碳反应生成碳化钙制备磷的热力学反应条件。计算结果表明在常压下反应温度1891 K,而在真空条件下压力在90~9 Pa反应进行的温度为1423~1320K。实验验证了热力学的准确性。     

碳化钙真空还原镁热力学分析及试验

本文通过对碳化钙还原MgO的化学反应热力学研究,计算得到:在常压下该反应的临界反应温度为2148 K;在真空条件时还原反应临界温度降低,当压力降低至1 kPa时,临界反应温度为1395 K.通过还原炼镁试验表明:随着反应温度升高,镁还原率提高;当在1150℃左右和1～2Pa真空条件下,可以获得80%以上的镁还原率.     

真空铁热还原氧化锂制备金属锂的热力学分析与实验初探

通过相关的热力学理论计算,对常压及真空条件下以碳酸锂为原料分解成氧化锂以及铁热还原氧化锂制备金属Li进行了热力学分析,计算结果表明:常压下碳酸锂很难发生分解反应,当系统压力降到1Pa时,碳酸锂的临界分解温度降为889K,并且真空中用铁还原氧化锂制备金属Li是可行的.并根据计算设计进行了铁还原氧化锂实验,实验结果表明:在热力计算上,系统压强为1～5Pa,温度为1423～ 1573 K的条件下,金属铁能还原出金属锂,锂的还原率为48％以上.     

氧化铝碳热还原氯化法制低价氯化铝反应的热力学研究

对氧化铝碳热还原氯化法制低价氯化铝的反应进行了热力学研究。经过热力学计算得到：在常压下，该反应发生的起点温度为2121．21K。而当系统压力下降时。该反应的起点温度也会下降；经过计算得到了该反应起点温度与系统压力间的关系，也得到了不同系统压力下反应吉布斯自由能与系统温度间的关系。     

CaC_2还原MgO热力学分析与实验研究

本文对常压及真空条件下以碳化钙为还原剂制取金属镁的热力学分析,计算出平衡状态下镁蒸汽的露点,并进行真空热还原实验研究.结果表明:常压下临界反应温度为2095K;当系统压力降至10~3Pa和10Pa,临界反应温度依次降为1376K和1030K;达到平衡时,还原温度1316K时,镁蒸汽的露点为熔点,还原温度为1273K、1373K时,露点分别为901K、958K.升高还原温度或延长还原时间可提高镁收率和CaC_2利用率;理论配比的反应物料在1423K条件下还原2h的镁收率为83.1%.而当还原时间达到2.5h,镁还原率和CaC_2利用率均超过80%.     

对真空条件下氧化锌制备锌的机理及冷凝的研究

本文对锌资源概况、制锌工业的现状与发展等方面进行了综述,对氧化锌真空碳热还原过程分别采用热力学、沸点、蒸气压计算进行分析。热力学计算结果显示,碳的热还原氧化锌反应的理论起始温度随着压强的减小而减小,由常压减小到10Pa时,起始温度由原来的1247K减小到473K;CO气体还原氧化锌反应常压下的理论起始反应温度为1198K,当压力降到10Pa时,起始温度降为404K,由沸点分析可知,分离比Zn高的沸点元素Pb、In、Al、Cu、Sn、Fe在热力学上是可行的;由饱和蒸汽压分析可知,粗锌中各组元的蒸馏顺序分别为:CdZnPbInSnAlCuFe。真空下,可以防止冷凝过程中二氧化碳与锌发生再氧化反应。由此,本文提出了采用真空炉的方法从氧化锌中制取锌的工艺。     

对氧化铝碳热还原-氯化法炼铝过程中碳化铝的氯化反应研究

采用热力学分析及X射线衍射、扫描电子显微镜及能谱仪等方法与手段,系统研究了中真空条件下碳化铝与氯化铝的反应。通过热力学研究,在10～100 Pa,温度低于1773 K时,Al与C生成Al4C3的反应及Al4C3与AlCl3的反应满足反应发生的热力学条件。实验研究表明,Al4C3可以通过Al与C反应制得;在1773 K、10～100 Pa下,Al4C3与AlCl3可以发生反应,并在冷凝区得到金属铝,热力学研究与实验研究完全一致。在真空碳热-氯化法炼铝过程中存在着Al4C3与AlCl3发生的反应,其是氯化过程中的重要反应之一。     

The wetting of carbon by aluminium and aluminium alloys

The contact angle made by molten aluminium with vitreous carbon was measured by the sessile drop method in vacuum at temperatures up to 1100° C. The effect on wetting behaviour of the oxide layer on the molten metal was highlighted by using two samples of aluminium in different states of oxidation. The investigation involved the variation of certain parameters affecting the stability of the oxide film, e.g. the temperature, additions of Ti, Si, Cr, Be, Ca and Li to aluminium and the time held at a certain temperature. The state of the molten aluminium surface under various experimental conditions was determined indirectly by surface tension measurements.     

Bending of square aluminium extrusions with aluminium foam filler

Summary An experimental programme consisting of 24 tests was carried out to study the three-point-bending behavior of square AA6060 aluminium extrusions filled with aluminium foam under quasi-static loading conditions. The outer cross section width and span of the beams were kept constant at 80 mm and 800 mm, respectively. The main parameters investigated were the foam density, the extrusion wall strength and the extrusion wall thickness. The experiments showed that the foam filler significantly altered the local deformation pattern of the beams. Simple design formulae were developed in order to predict the load bearing capacity of the foam filled beams.Notation d load cell displacement - total beam rotation - ₀₂ total beam rotation at extrusion flange yielding (non-filled beam) - ₁, ₂ beam end rotations - b outer component cross section width - h component wall thickness - L total beam span length - s central load section of beam - A _e extrusion cross sectional area - A _f foam cross sectional area - P load cell force - M total cross section moment - M _e extrusion moment - M ₀₂ maximum elastic moment capacity of extrusion - M _pl perfect plastic moment capacity of extrusion - M _f foam core moment - M _sf maximum foam core moment - M _s total initial peak moment - M _sa total moment capacity after foam failure - M _u ultimate extrusion moment capacity - M _se calculated moment resistance of extrusion at foam failure - stress, engineering - ₀₂ extrusion wall stress at 0.2% plastic strain - _U extrusion wall ultimate stress - ₀ extrusion wall characteristic stress, 0.5(₀₂+ _U ) - _f foam plateau stress - _s foam tensile failure stress - strain, engineering - ₀₂ extrusion strain corresponding to yield stress ₀₂ - _u extrusion strain corresponding to ultimate stress _U - _s foam tensile failure strain - beam curvature - ₀₂ beam curvature at extrusion flange yielding - _u beam curvature at extrusion ultimate stress - _s beam curvature at foam tensile failure strain - f extrusion section shape factor - k elastic bending stiffness ratio between foam core and extrusion - E extrusion Young's modulus - E _t extrusion tangential modulus - n extrusion material hardening constant - _f foam density - _i foam batch density,i=1, 2, 3 - x, y, z coordinate reference system (x-beam axis) - x _c distance from beam end (change in formula for curvature)     

Wettability of aluminium nitride by tin–aluminium melts

The wettability of aluminium nitride by Sn–Al melts was studied by the sessile drop method in a vaccum of 2 × 10^–3 Pa at 1100 °C over the whole concentration region. The minimum interval on the contact-angle concentration dependence curve was observed at intermediate composition. For comparison, experiments were also performed on porous AlN. Wetting of porous nitride is worse than the dense nitride. The results have been analysed on the basis of the relation between wettability and the chemical interface reactivity in solid–liquid metal systems.     

Superior high-temperature resistance of aluminium nitride particle-reinforced aluminium compared to silicon carbide or alumina particle-reinforced aluminium

Aluminium-matrix composites containing AlN, SiC or Al₂O₃ particles were fabricated by vacuum infiltration of liquid aluminium into a porous particulate preform under an argon pressure of up to 41 MPa. Al/AlN had similar tensile strengths and higher ductility compared to Al/SiC of similar reinforcement volume fractions at room temperature, but exhibited higher tensile strength arid higher ductility at 300–400 °C and at room temperature after heating at 600 °C for 10–20 days. The ductility of Al/AIN increased with increasing temperature from 22–400 °C, while that of Al/SiC did not change with temperature. At 400 °C, Al/AlN exhibited mainly ductile fracture, whereas Al/SiC exhibited brittle fracture due to particle decohesion. Moreover, Al/AlN exhibited greater resistance to compressive deformation at 525 °C than Al/SiC. The superior high-temperature resistance of Al/AlN is attributed to the lack of a reaction between aluminium and AlN, in contrast to the reaction between aluminium and SiC in Al/SiC. By using Al-20Si-5Mg rather than aluminium as the matrix, the reaction between aluminium and SiC was arrested, resulting in no change in the tensile properties after heating at 500 °C for 20 days. However, the use of Al-20Si-5Mg instead of aluminium as the matrix caused the strength and ductility to decrease by 30% and 70%, respectively, due to the brittleness of Al-20Si-5Mg. Therefore, the use of AIN instead of SiC as the reinforcement is a better way to avoid the filler-matrix reaction. Al/Al₂O₃ had lower room-temperature tensile strength and ductility compared to both Al/AlN and Al/SiC of similar reinforcement volume fractions, both before and after heating at 600 °C for 10–20 days. Al/Al₂O₃ exhibited brittle fracture even at room temperature, due to incomplete infiltration resulting from Al₂O₃ particle clustering.     

纯铝经氢氧化铝制备氧化铝超滤膜涂膜液的研究

利用价格便宜的纯铝经氢氧化铝沉淀制备成用于制备超滤膜的涂膜液.采用丁达尔现象和过滤观测法判定制备液是否为溶胶,采用离心沉降光度法研究分析溶胶的颗粒大小和稳定性,来研究制备稳定涂膜液的最佳条件.研究结果表明,用纯铝经氢氧化铝沉淀制备涂膜液的最佳选择制备条件为1 g/100 mL的氢氧化铝加入量,加酸量为1 mol/L硝酸溶液∶氢氧化铝=15 mL∶1 g,在85℃下,搅拌6 h.     

Wetting of aluminium oxide by molten aluminium and other metals

The sessile drop technique has been used to measure the contact angle of molten aluminium, aluminium-nickel and aluminium-copper alloys, copper and gold, with sapphire, ruby and recrystallised alumina. Measurements were madein vacuo, and as a function of time and temperature over the range 800 to 1500° C. Cinematography and time-lapse photography were used. At temperatures below 950° C, sessile drops of aluminium reached equilibrium only after a period of time which increased with decrease in temperature and could be in excess of one hour. A rapid increase in contact area occurred around 900° C. Above 1150° C drops of aluminium and of the aluminium alloys were observed to spread and contract repeatedly. Contractions were observed with both polycrystalline and single-crystal alumina, although they were much more pronounced with the latter, and were associated with the formation of a series of reaction rings on the plaque. Ruby and sapphire behaved similarly. The shape of the rings depended on the crystallographic orientation of the plaque: the reaction profile tended to terminate in certain low index directions. Neither contractions nor reaction was observed with copper or gold. The observations are discussed in terms of the combined effects of evaporation, chemical reactivity and interfacial tensions in the system.     

Nitrogen-containing aluminium titanate

In the Ti-Al-O-N system a phase isostructural to aluminium titanate but with expanded unit cell dimensions was observed. It was stable between 1400 and 1700 °C and has unit cell dimensions of a=0.3719 nm, b=0.9703 nm and c=0.9869 nm with a composition of Ti _1.00 ⁴⁺ Al _0.54 ³⁺ Ti _1.46 ³⁺ N _0.28 ^3– O _4.58 ^2– _0.14 Several samples were prepared by reaction sintering mixtures of TiN, Al₂O₃ and AlN powders at 1400 to 1470 °C for 4 h in a nitrogen atmosphere to maximize this phase. One specific advantage of the nitrogen-containing aluminium titanate over aluminium titanate is that the former is unchanged at 1150 °C in a nitrogen atmosphere whereas the latter decomposes. In the Al₂O₃-TiO₂ oxide system Al₂TiO₅ solid solution extends to approximately Al_0.75Ti_2.25O₅ at 1470 °C under the mildly reducing conditions of a graphite furnace. The unit cell volume increases linearly with the increasing replacement of Al³⁺ by Ti³⁺.