高掺量粉煤灰高延性水泥基复合材料的制备和性能

高延性水泥基复合材料(hjgh ductility cementitious composites,HDCC)是一种具有应变硬化、多缝开裂和高延性等特性的新型纤维增强水泥基复合材料,其材料设计必须取得基体韧度、界面黏结和纤维特性三者的最优组合,因此,HDCC的制备必须优选原材料和优化配合比,以取得最优的材料制备技术.从配合比设计入手,研究了粉煤灰含量、胶砂比等对HDCC力学性能的影响,优化了特定材料下的材料制各技术.结果表明:粉煤灰含量、胶砂比和养护条件对HDCC的拉伸性能均具有较大的影响.随着粉煤灰掺量的增大,砂含量的降低,拉伸应变增大.当砂含量较高时,基体开裂韧度较高,基体的极限拉伸应力下对应的极限拉伸应变较小,然而随着应力的下降,复合材料仍然能维持相当大的应变·     

铁矿球团生球的固结机理及强化途径

通过生球强度破坏机理分析,得出通过对造球原料进行润磨可以有效的增大晶粒间的范德华力,增加生球的机械强度,添加能够通过范德华力、静电力、氢键、化学键、配位键等与铁矿颗粒表面发生作用的粘结剂也可以有效地提高生球的机械强度;提高球团的爆裂温度的有效方法是均衡球团表面气化和内部扩散作用,均衡球团表面气化和内部扩散作用的主要措施是降低球团表面气化的速度,使表面扩散速度减小,添加具有亲水基的有机粘结剂和膨润土可以降低自由水或毛细水的扩散速度,提高球团的爆裂温度;通过对造球原料的改性对生球的强度的提高是有限的,添加有机粘结剂或复合粘结剂强化生球强度仍然是今后发展的一个重要方向。     

不同粘结剂对碳纳米管红外吸收涂层性能的影响

碳纳米管涂层已在低温工作环境中大量应用,所选用的粘结剂在很大程度上影响其红外吸收性能及与基体的结合性能。分别用水玻璃粘结剂和磷酸盐粘结剂与碳纳米管、镍粉混合制成涂料,并将其涂覆在铜基体表面。采用XRD和SEM对涂层的红外吸收性能、物相、晶体结构及形貌进行了表征;测试了涂层的抗热震性能。结果表明:当粘结剂为磷酸盐、含量为90%~85%时,1 400~3 570 cm~(-1)(2.80~7.14μm)波段内涂层的平均光吸收度达1.992~2.084,红外吸收性能最佳,抗热震次数可达35次(25~120℃),满足了用户要求(10次)。     

公路工程无机结合料击实试验研究

从取料、制料以及对试验各环节的控制等方面,对如何获得准确的无机结合料击实试验数据进行了探讨。     

A study of the effects of pavement ageing on binder deterioration

This paper discusses the ageing of asphalt binder of long-term pavement performance (LTPP) sites in Southeast Queensland. The effects of pavement age on binder deterioration were examined by performing ‘Shell’ sliding plate micro-viscometer laboratory tests in accordance with Australian and New Zealand Standard AS/NZS 2341.5: 1997. The tests were carried out on bituminous core samples obtained from the LTPP sites to determine the apparent viscosity of the asphalt binder. A binder deterioration model (BDM) was developed by establishing a relationship between the apparent viscosities of the binder with pavement age. The apparent viscosity data generated using the BDM were compared with that computed using the bitumen hardening model developed by Oliver (2003). The two models show a consistent trend in the binder deterioration, and the results were analysed statistically using regression analysis, Root Mean Square Error and t-test methods. The t-test shows that the data generated by the BDM have no significant deviation from the prediction by Oliver's model.     

Reconstruction and hydration of hydrotalcite response to thermal activation temperature: Enhancement of properties for magnesia castables

Optimization binding system for refractory castables is significant to enhance the service performance. Hydrotalcite has been considered a promoter for high-temperature performance of basic castables, however, its binding property remains to be improved before practical application. In this work, the thermal activated Mg–Al hydrotalcites were incorporated in magnesia castables, and the mutual influence of pre-calcination temperature on the hydration, microstructure, and strength of castables was investigated. The obtained results indicated that the reconstruction of calcined hydrotalcite took place in the hydration process and effectively motivated the hydrolysis. Hydrate was thus promoted and a relatively dense microstructure of magnesia castables was confirmed by X-ray computed tomography analysis. Hydrotalcite pre-calcinated at 300 °C contributed to the highest early strength for castable, and the high-temperature properties also performed better than that of other pre-calcinated hydrotalcite-adding. The enhancement mechanisms of calcined hydrotalcite were attributed to the two following reasons: (ⅰ) the modified microstructure of magnesia castables from the early stage by hydration process, (ⅱ) the further enhanced sinterability inspired by the appropriate thermal activation effect.     

乙烯基硅油改性苯丙乳液粘合剂的制备及应用

采用丙烯酸酯单体制备苯丙乳液粘合剂,用乙烯基硅油对其进行改性。探讨了乙烯基硅油的用量对乳液性能、胶膜性能的影响,及硅油改性粘合剂的用量对棉织物印花性能的影响。对改性粘合剂进行了红外光谱、热重分析、透射电镜等表征。结果表明,乙烯基硅油用量为9%时,乳液外观、胶膜及印花性能较好;乙烯基硅油改性粘合剂用量为6%时,印花织物的手感柔软、摩擦牢度较好。     

Fluorine-free binders for Carbon Black based Electrochemical Supercapacitors

Industrially manufactured carbon blacks (CBs) provide highly dispersed carbon materials with a specific surface of up to 1700 m² g^–1. Precompaction at p > 10 MPa in the presence of 3–10 wt% PTFE (provided as a dispersion) is known to lead to stable electrodes for electrochemical supercapacitors. Specific capacitances for single electrodes (C _s,1) were measured by constant current cycling (CCC) at 34 mA cm^–2 to be up to 250 F g^–1. It is shown that substitution of PTFE by fluorine-free binders, such as aqueous dispersions of polystyrene, styrene/butadien-copolymer and ethylene/acrylic acid copolymer is possible. Optimum systems were with 3–10 wt% binders of butadiene/styrene copolymers. They allowed stable results within hundreds of cycles. No shedding of the CB particles was observed, and swelling of the electrode was minimum.     

锂离子电池浆料稳定性的优化

采用浆料稳定性测试仪、粘度计等测试方法研究了搅拌工艺、固含量、浆料粘度与稳定剂等因素对锂离子电池浆料稳定性的影响。结果表明:取代度大、粘度高的CMC(羧甲基纤维素钠),有利于提高电池浆料的稳定性。对于A1负极配方,采用高粘度搅拌工艺,选用B种CMC,固含量控制在46%,浆料粘度控制在4 000 m Pa·s时,制备的浆料稳定性能最佳。     

基于喷射粘结工艺的陶瓷坯体后处理性能调控

商用设备在进行陶瓷坯体成形时不易对坯体组织进行调控,难以成形高致密坯体,且常压后处理强化效果较差.基于自开发成形系统和自有材料,通过调节成形粉末配方、调控铺粉层厚、切换铺粉方法等调控Al2O3坯体的成形组织,成形了相对密度为43.9%的高致密坯体。采用“陶瓷浆料渗透+分步烧结”综合化后处理流程研究了不同坯体组织的渗透强化机理,并以此为依据对预烧结过程进行调控,显著提升了高致密成形坯体的最终性能,常压烧结后相对密度达89.3%,抗弯和抗压强度分别为91.9 MPa和813.2 MPa。该研究所用材料、工艺和装备仪器门槛低、易操作,为制备高性能结构陶瓷提供了一种灵活、快捷的技术方案。