SAN/CPE/PC合金的制备与性能研究

利用氯化聚乙烯(CPE)弹性体、苯乙烯-丙烯腈(SAN)以及聚碳酸酯(PC)共混制备了高韧性的SAN/CPE/PC合金。研究了不同含量的PC对PC/SAN/CPE合金性能的影响。结果表明:随着PC用量的增加,合金的缺口冲击强度逐渐增加,拉伸强度逐渐降低。当SAN/PC的质量比为50/50,CPE质量分数为10%时,缺口冲击强度达到14 kJ/m2,接近于SAN/CPE二元体系CPE质量分数为40%时的缺口冲击强度。合金熔体质量流动速率随着PC含量的增加逐渐降低。     

A Study of the Fundamental Process of applying CAD to Steel Casting Production

The authors present a study of the fundamental process of applying CAD in the production of steel castings with a view to optimising the casting process. A rolling-mill frame was selected as the basis of the work. In the study, a comparison is made between the Saul'yev technique and the boundary element method, using numerical calculation, combined with technical experiment. It is proved that the Saul'yev technique is more suitable for the three-dimensional simulation of steel casting solidification. On this basis the authors have developed a CCAD Software system. In this approach, the blueprint of the machine part can be fed into the computer, allowing the production method, together with the necessary parameters to be determined. Guided by the Chvorinov-Wlodawer (CW) rule, and the principle of hydrodynamics, it is then possible to design the gating and feeding systems. Using numerical simulation, the quality of the casting, produced by the projected design, can be assessed during the animated display of the solidification process. The presentation allows corrections to be made until such time that the designer is satisfied with the methodology. Finally, the production drawings can be produced with the aid of a plotter.     

超大型钢混凝土柱脚灌浆施工技术

随着社会的发展,超高层建筑越来越多,型钢混凝土结构能够极大的减少混凝土柱截面尺寸,因此普遍应用在超高层建筑中。本文阐述了钢柱柱脚与混凝土底板之间二次灌浆的施工工艺及操作要点,可确保型钢柱脚灌浆的密实性,保证工程施工质量。     

Casting characteristics of high silicon added F3S.20S Duralcan composites

Fluidity and castability studies were carried out for F3S.20S (Al-20SiCp) Duralcan composites with additional amounts of silicon. The fluidity measurements were carried out using the gravity casting method and the castability studies using Low Pressure Casting (LPC) as well as gravity pouring methods. It was observed that with both the gravity and LPC methods, the fluidity and castability were found to increase, with the increasing silicon levels (up to 20 wt%) present in the composites. The castability of the composite was increased with each increase in temperature for the range of temperatures studied (1003,1013 and 1033 K).     

PPE黏度对MPPE性能的影响

采用双螺杆挤出,在相同工艺条件下制备了四种改性聚苯醚(MPPE)产品,研究了不同特性黏度的聚苯醚(PPE)对MPPE性能的影响.结果表明:随着PPE黏度的增加,MPPE的力学性能明显提高,耐热性能有较大改善;但熔体流动速度变慢,成型加工性能有所降低.     

Use of phenolic resin in coke making at Tata Steel

Quality of coke is very much important for blast furnace productivity. Phenol-formaldehyde resin can be used as an additive in small quantity in the coal blend for improvement of coke quality. It enhances the fluidity of coal blend during co-pyrolysis with coal and hence improves the coke quality. After successful lab-scale study, this phenomenon has been demonstrated in top charge battery and heat-recovery oven of Tata Steel through plant trial. It was found that 0.3–0.4% addition of phenolic resin in the coal blend improves coke quality.     

Performance of mortar prepared with recycled concrete aggregate enhanced by CO2 and pozzolan slurry

One of the most promising strategies to manage the large volume of construction and demolition (C&D) waste is recycling and utilizing it for the production of new concrete. However, recycled concrete aggregate (RCA) derived from C&D waste possesses relatively higher porosity and water absorption capability, which often limits its wild utilization. In this study, pozzolan slurry (includes silica fume, nano-SiO₂, and fly ash slurries) and CO₂ treatments as enhancement methods for RCA were investigated. Test results showed that CO₂ treatment was more effective in reducing water absorption and enhancing fluidity, whereas pozzolan slurry treatment could decrease fluidity. Mortars prepared with treated RCA exhibited better mechanical strength and higher resistance towards carbonation and chloride-ion diffusion than those with untreated RCA. Both pozzolan slurry and CO₂ treatments enhanced not only the properties of RCA, but also the old and new interfacial transition zones (ITZs) as demonstrated in the measured micro-hardness and SEM observation.     

稀土对铸造铝铜合金流动性和热裂倾向性的影响

研究了富Ｃｅ混合稀土对铸造铝铜系高强度ＺＬ２０１Ａ合金的流动性和热裂倾向性的影响。结果表明，稀土能不同程度地提高合金的流动性和降低合金的热裂倾向性，明显地提高合金的铸造性能。分析表明，合金流动性的提高和热裂倾向性的降低，主要是由于稀土的加入使合金在凝固过程中枝晶细化，在凝固后期枝晶的联生增强。     

镁合金真空低压消失模铸造流动性的研究

真空低压消失模铸造是一项新材料与新工艺相结合的新技术,具有充型平稳、尺寸精确、压力下凝固等技术优势。着重研究镁合金真空低压消失模铸造的流动性及其与主要工艺参数的关系,探讨了真空低压消失模铸造镁合金的流动性,分析了浇注温度、涂层厚度和充气流量对镁合金流动性的影响,并进行工艺优化。研究结果表明,镁合金真空低压消失模铸造的流动性显著提高,且随着充气流量的升高和涂层厚度的降低而提高,其最佳工艺参数为:充气流量3~5m3/h,浇注温度750~780℃,涂层厚度0.3~0.5mm,泡沫材料密度为0.16mg/cm3,真空度应控制在0.03MPa以下。     

形变率对AZ91D镁合金半固态成形组织及流动性的影响

采用SIMA法制备半固态浆料,通过半固态挤压成形,研究了形变率对AZ91D镁合金半固态成形组织及流动性的影响.结果表明:形变率从10%增加到20%,晶粒平均尺寸变小,圆整性提高,液相比例增大,流动性能得到改善.在565 ℃保温10 min,形变率为10%的试棒可得到形状基本完整的挤压成形件,20%的流动性最好;当形变率增加到30%时,晶粒的圆整性进一步提高,但平均尺寸反而增大,流动性降低.试验条件下最佳的形变率为20%.