Identification and evaluation of modification level for compacted graphite cast iron

The shape of the freezing zone of a thermal analysis cooling curve not only contains the information about the modification level of compacted graphite cast iron (CGI) right after vermicularizing treatment, but also reflects the following fading process during holding. When the freezing zones of two cooling curves are approximately the same, graphite morphologies of the samples cast from the two corresponding melts right after vermicularizing treatment are similar, and those of the two corresponding samples cast after holding for the same period are similar too. Based on the pattern recognition method and database established from a large amount of experimental results, the shape of the freezing zone of a cooling curve can be used to identify the modification level of CGI melt and on-line prediction of a CGI melt quality has been realized.     

PVC稀土热稳定剂的研究和应用进展(上)

介绍了聚氯乙烯(PVC)稀土热稳定剂的稳定机理、合成研究及应用进展,指出了今后的发展前景及趋势.     

Selective Growth of Vertical-aligned ZnO Nanorod Arrays on Si Substrate by Catalyst-free Thermal Evaporation

By thermal evaporation of pure ZnO powders, high-density vertical-aligned ZnO nanorod arrays with diameter ranged in 80–250 nm were successfully synthesized on Si substrates covered with ZnO seed layers. It was revealed that the morphology, orientation, crystal, and optical quality of the ZnO nanorod arrays highly depend on the crystal quality of ZnO seed layers, which was confirmed by the characterizations of field-emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and photoluminescence measurements. For ZnO seed layer with wurtzite structure, the ZnO nanorods grew exactly normal to the substrate with perfect wurtzite structure, strong near-band-edge emission, and neglectable deep-level emission. The nanorods synthesized on the polycrystalline ZnO seed layer presented random orientation, wide diameter, and weak deep-level emission. This article provides a C-free and Au-free method for large-scale synthesis of vertical-aligned ZnO nanorod arrays by controlling the crystal quality of the seed layer.     

Microstructure and thermal properties of copper matrix composites reinforced with titanium-coated graphite fibers

Milled form of mesophase pitch-based graphite fibers were coated with a titanium layer using chemical vapor deposition technique and Ti-coated graphite fiber/Cu composites were fabricated by hot-pressing sintering. The composites were characterized with X-ray diffraction, scanning/transmission electron microscopies, and by mea-suring thermal properties, including thermal conductivity and coefficient of thermal expansion (CTE). The results show that the milled fibers are preferentially oriented in a plane perpendicular to the pressing direction, leading to anisotropic thermal properties of the composites. The Ti coating reacted with graphite fiber and formed a continuous and uniform TiC layer. This carbide layer establishes a good metallurgical interfacial bonding in the composites, which can improve the thermal properties effectively. When the fiber content ranges from 35 vol% to 50 vol%, the in-plane thermal conductivities of the composites increase from 383 to 407 Wá(máK) -1 , and the in-plane CTEs decrease from 9.5 9 10-6 to 6.3 9 10 -6 K-1 .     

Pore-level numerical simulation of methane-air combustion in a simplified two-layer porous burner

A simplified two-dimensional model of two-layer porous burner based on pore level is developed.The heat transfer of solid phase in porous burner is seen as the synergistic effects of conduction through con-necting bridges and surface radiation between the solid particles in the model.A numerical simulation study on the characteristics of flow,combustion and heat transfer in the two-layer porous burner is car-ried out using the pore level model,and the effects of the control parameters such as the inlet velocity and solid thermal conductivity on thermal non-equilibrium are investigated.The results show that the flame structure is highly two-dimensional based on pore level.Obvious thermal non-equilibrium in the burner for the two phases and solid phase are observed,the largest temperature difference between the gas and solid phases is observed in combustion zone,while the temperature difference inside the solid particles is largest near the flame front.The results also reveal that thermal non-equilibrium of por-ous burner is much affected by the inlet velocity and solid thermal conductivity.     

炼油厂加热炉节能方案分析

我国炼油厂加热炉普遍存在排烟温度高和热效率低的缺点 ,具有较大的节能改造潜力。根据某炼油厂加热炉的热平衡实验报告 ,对部分加热炉提出了节能改造方案。分析结果表明 ,该方案能取得较好的节能效益     

高氮量硝化棉的脱硝反应动力学研究

用实时测定凝聚相分解产物的固体原位反应池／快速扫描傅立叶变换红外光谱热技术研究了高氮量硝化棉的脱硝反应动力学,该反应的动力学参数用改良的Ｃｏａｔｓ－Ｒｅｄｆｅｒｎ法计算,根据所得结果,提出了在４０３－４６５Ｋ温度范围内描述高氮量硝化棉脱硝反应的微分动力学方程。     

黑火药和单基发射药的电热丝点火实验研究

用实验方法研究了黑火药和单基发射药在电热丝作用下的点火问题 ,测出了实验条件下两种药剂的临界点火电流及点火延滞期 ,并推算出了点火的电热丝温度。