THERMODYNAMICS OF BAINITIC TRANSFORMATION IN Cu-24 at.-% Al ALLOY

Two driving forces △G~((β_1)+α')and △G~(β_1→β_2+α)for the bainitic transformation have been calcu-lated for Cu-24 at.-% Al alloy.Results reveal △G~(β_1→α')>0 within the transformation tem-perature range 600—750 K.Therefore,the bainitic transformation cannot be initiated by theβ_1→α' shearing mechanism.On the other hand,the driving force △G~(β_1→β_2+α)to produce 5% ofthe α becomes negative only when the composition of the α satisfiesx_(Al)~α≤0.204 at 700 K or x_(Al)~α=0.209 at 750 K.So the bainitic transformation can only proceedby β_1→β_2+α diffusional reaction with different diffusion amount at different temperatures.     

不可逆量子斯特林热泵循环性能分析与优化

建立了以一维无限深势阱中极端相对论粒子为工质的不可逆量子斯特林热泵循环模型。考虑高低温热源之间的热漏,导出了循环的性能系数与无量纲泵热率的表达式。分析了循环性能与各性能参数之间的关系。研究发现,热泵的性能系数与无量纲泵热率都随粒子在状态1进处于激收态上的占有几度单调递减,性能系数与无量纲泵热率都是势阱宽度比的凸单调函数。无量纲泵热率关于性能系数的关系曲线为回原点的扭叶型,并确定了该不可逆量子斯特林热泵的最优运行区间。     

Degradable Superhydrophilic Iron-Pillared Bentonite Doped with Polybutylene Adipate/Terephthalate Open-Cell Foam: Its Application in Dye Degradation,Removal of Heavy Metal Ions,and Oil–Water Separation

Development of industrialization has brought convenience to people's lives; however, it has also brought serious harm to the environment, where, water pollution is the most obvious. Here, a polybutylene adipate terephthalate (PBAT) open-cell foam doped with iron-pillared bentonite (IPB) is prepared by using sugar as a pore-forming agent and solution phase separation, and then combined with a solution dipping method to coat the foam surface with a polyacrylamide/SiO₂, which makes the PBAT foam superhydrophilic. The static adsorption effect of superhydrophilic IPB-doped PBAT open-cell foam on methylene blue (MB) and Cu²⁺ is studied. The adsorption isotherm fitting shows that the adsorption conforms to the Langmuir model and it has biased toward monolayer adsorption. The adsorption kinetics fitting confirms that the adsorption process is in line with the pseudo-second-order adsorption model, which is dominated by chemical adsorption. The modified PBAT open-cell foam has an adsorption effect on Cu²⁺; however, it has weak cyclic adsorption capacity. It shows a good cyclic adsorption ability for the cationic dye MB and it has >95% photodegradation efficiency of the MB after five time's cyclic adsorption. The superhydrophilicity makes the foam to have better applications in oil–water separation.     

The laws of silicon ingot formation by combustion reaction

The formation of a phase pure silicon ingot from SiO₂+Al+KClO₃ and Na₂SiO₃+Al+KClO₃ systems was investigated thermodynamically and experimentally under combustion mode, known also as self-propagating high-temperature synthesis (SHS). The regularities of combustion and phase formation versus KClO₃ concentration by a thermocouple technique were obtained. The morphology, chemical and phase composition of the silicon ingot were analyzed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and ICP-analysis. The method reported here proved effective in producing silicon ingots with a purity of 98%.     

含钛高炉渣制备CaTiO3-多孔地质聚合物光降解吸附材料

含钛高炉渣作为固体废弃物,国内存量巨大,且其中的钛组元难以提取,导致含钛高炉渣综合利用一直没有得到有效解决。针对当前含钛高炉渣利用率低、附加值低等问题,基于含钛高炉渣成分特点,通过选择性析晶(CaTiO₃优势析出)、碱激发,制备出CaTiO₃-多孔地质聚合物的复合材料。试验结果表明,析晶温度1 400 ℃、保温1 h能够促进CaTiO₃的优势析出,而剩余氧化物以玻璃相形式存在。制备出的CaTiO₃-多孔地质聚合物材料结合了CaTiO₃高光催化活性与多孔地质聚合物比表面积大的优点,对亚甲基蓝具有优异的吸附效果,最大吸附量可达60.4 mg/g。在投加量为50 mg,2 h吸附、3 h光降解条件下,对亚甲基蓝去除率可达94.5%,在治理有机污染领域有良好的应用前景。     

Sulfur in chromia

The solubility of sulfur in chromia has been studied in H₂-H₂O-H₂S tagged with³⁵S at 973 and 1173 K at low oxygen and sulfur partial pressures typical for coal gasification-systems. For monocrystalline samples, it has been shown that sulfur-containing species are only present adsorbed on the surface of the specimens and can be removed by ultrasonic cleaning in acetone. The surface coverage after 4 weeks of exposure to H₂-H₂O-H₂S was between 2.8 and 19.3% of a monolayer. In polycrystalline chromia, sulfur was located only in pores and cracks of the sample. In dense, compact areas of the specimens the solubility of sulfur was below the detection limit of autoradiography, which was estimated to be better than 0.17 ppm.     

ADSORPTION MECHANISMS OF HS-IONS ON SULPHIDE MINERAL SURFACES RELATED TO Na_2S-INDUCED FLOTATION

The adsorption mechanisms of HS~- ions existing in air-saturated alkaline solutions on sulphide minerals (including pyrite, arsenopyrite, chalcopyrite and galena) were investigated. The measurement of adsorption density, solvent extraction-chemical analysis of neutral sulphur at the surfaces, measurements of pulp potential and voltammogram, and flotation tests were done. Both the electrochemical and non-electrochemi cal adsorption models of HS~- ions were established. The former was observed and resulted in the formation of neutral sulphur (S°)when the pyrite and arsenopyrite were chosen, and hence renders the surfaces hy drophobic and induced the two minerals flotation. It is called Na_2S-induced flotation. On the other hand, the latter took place and did not produce S° when the chalcopyrite and galena were selected, and hence de presses the collectorless flotation of the two minerals. The adsorptions of HS~- ions were mainly influenced by potentials, pH and the electron structures of the mineral surfaces.     

Experimental study of NiO electrical conductivity changes under low oxygen pressures

The electrical conductivity of NiO was measured at 740°C in an oxygen pressure range of 10^–2 –1.3 Torr. By means of continuous recording, longtime experiments were performed. The results show that for any admittance of oxygen, the electrical conductivity initially increased and then decreased to its initial value. For pressures higher than 0.1 Torr the decrease of the signal was reduced and the time required to attain the initial value sometimes reached several days. These results suggest that the electrical conductivity changes may be considered as a transitory phenomenon connected to attaining gassolid equilibrium.     

碱性电镀光亮锌镍合金研究

研究了镀液的组成与镀层中镍含量、镀层的相结构以及阴极电流效率的关系。提出了碱性电镀光亮锌镍合金的最佳镀液组成和工艺规范,并对茴香醛、四乙烯五胺和ZN—A5添加剂的吸附行为及其对锌镍电沉积过程的阻化作用进行了探讨。