Studies on slip casting behavior of lanthanum strontium manganite

Dispersion conditions for slip (slurry) formulation of a powder mixture of lanthanum strontium manganite (La_0.84Sr_0.16MnO₃ - LSM) and carbon (pore former) in water was studied through detailed zeta-potential and rheological measurements. The zeta potential variation with pH for the aqueous suspensions of only LSM or carbon exhibited a maximum value in alkaline medium (−40 mV to −50 mV at a pH of 10-11), establishing the pH window for their co-dispersion for slurry formulation. A study of the viscosity variation with shear rate for the slurries with varying solid content (in the range of 45-65 wt.%) exhibited pseudo-plastic flow behavior, indicating presence of flocculates in them. The yield stress values obtained from the Casson equation reduced with decreasing solid content, indicating reduction in the flocculate strength. The slip with solid content of 50 wt.% exhibited optimum flow characteristics to form long tubes with uniform wall thickness (wall thickness 2-4 mm and length of 150-200 mm). The tubular specimens formed after controlled carbon burn out and sintering at 1400 °C for 1 h possessed about 35% open porosity. The porosity remained the same upon further sintering at 1400 °C for 8 h.     

Preparation and Properties of Biodegradable Polymer Film Based on Polyvinyl Alcohol and Tropical Fruit Waste Flour

In this study, two different types of tropical fruit waste flour, rambutan waste flour (RWF) and banana waste flour (BWF), were blended with polyvinyl alcohol (PVOH) by solution casting method. The structure of the blend film was characterised by Fourier Transform Infrared Spectroscopy. The tensile strength and elongation at break of tropical fruit waste flour-filled polyvinyl alcohol were lower, but the tensile modulus was higher, than that of PVOH film. At a similar blend ratio, the tensile properties of the PVOH/RWF film were higher than the PVOH/BWF film, but the PVOH/BWF film showed higher water uptake than PVOH/RWF film.     

横向铸造结晶器的改进

介绍一种用机械套装的热顶代替传统的手工制作的喇叭碗或硅酸铝纤维套的结晶器。具有使用寿命长、经济效益好，更有利于抑制铸锭偏析瘤的特点。同时铸造温度范围更宽，铸造速度可达２２０ｍｍ／ｓ。     

铸轧工艺对产品质量的影响

讨论了铸轧区，铸轧速度，铸轧温度等对轧制力，铸轧板坯质量的影响，并根据实践对影响机理进行了探讨。     

Cast structure and property variability in gamma titanium aluminides

Aspects of cast structure that influence mechanical property variability, and in particular tensile ductility, have been studied in a Ti-48Al-2Cr-2Nb titanium aluminide alloy. Macrostructure, porosity, microstructure and tensile properties have been characterized over a range of casting processing conditions. Local solidification times and subsequent solid-state cooling rates during casting have been characterized via local thermal measurements in combination with solidification modeling. Large variations in cooling rate during casting dramatically influence the initial cast structure as well as the distribution of defects such as porosity. Variations in as-cast structure persist through subsequent thermal and hot isostatic pressing cycles and contribute to the variability of tensile ductility. The current understanding of the relationship of tensile ductility to processing-induced changes in structure will be briefly discussed.     

冰模快速成形及其在铸造中应用的研究

采用FDM方法，离散式喷射实现了冰模快速成形。介绍了试验用快速成形硬件系统及工艺参数，分析了用冰模代替陶瓷型模和熔模铸造出蜡模的工艺流程。造型工艺。根据由冰模所翻制铸件的尺寸对铸件收缩率进行了研究。     

A study on the solid-liquid 2 phase helical flow in an inclined annulus

An investigation is conducted to understand hydraulic transport characteristics of a solid-liquid mixture flowing vertically upward. Namely, this is the instance that solid particles are carried by non-Newtonian fluids in a slim hole concentric annulus with rotating inner cylinder. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. The bulk axial velocities varied from 0.4 m/s to 1.2 m/s. The mud systems which were utilized included aqueous solution of sodium carboxymethyl cellulose (0.2∼0.4%CMC) and 5% bentonite solutions. Solid volumetric concentration and pressure drops were measured for the various parameters such as inclined annulus, flow rate, and rotational speed of inner cylinder. For both CMC and bentonite solutions, the higher the concentration of the solid particles are, the larger the pressure drops become. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.     

牵引电动机机座铸造裂纹分析及对策

以韶山型电力机车８００ｋＷ电动机机座为例，分析了厚大圆筒类机座铸造裂纹特征及产生裂纹的主要原因；提出了防止裂纹产生的措施，获得了比较理想的效果，为解决厚大圆筒类铸钢件裂纹问题提供了思路。     

厚板坯连铸新技术

介绍了最近开发成功并应用的三项厚板坯连铸新技术 :人为鼓肚轻压下 ,二次喷淋新技术及在线快速调厚调宽的零号扇形段。     

连铸坯角部纵裂分析及对策

通过分析电炉连铸坯产生角部纵裂纹的原因，提出了具体的控制措施，加强原材料的质量控制和连铸工艺过程的控制对防止铸坯产生角部纵裂纹有着重要作用。