苛性白云石与菱苦土复合制备砂轮结合剂的研究

本文研究了苛性白云石制备氯氧镁水泥，其适宜的煅烧温度为750℃-850℃，煅烧时间为3—6h。通过力学性能对比试验，表明苛性白云石、菱苦土制备的氯氧镁水泥，二者在强度上相差无几，且前者早期强度更高；若二者按一定比例混合制备复合氯氧镁水泥，由于活性MgO含量的增加和弥散分布的活性CaCO3粒子的增强作用，物理力学性能得到很大改善。苛性白云石中添加菱苦土最佳比例是40—70％。将苛性白云石与菱苦土复合制备氯氧镁水泥作砂轮结合剂，其磨削效率、磨削比、工件表面质量均优于纯菱苦土作结合剂的砂轮。     

以白云石和菱镁石的混合物为原料真空铝热还原法炼镁过程的动力学（英文）

研究真空铝热还原煅烧白云石和煅烧菱镁石的混合物炼镁过程的动力学,提出一种满足真空铝热过程的等温还原方法。实验在4 Pa的真空下进行。实验结果表明:还原率随着温度、制团压力和铝粉添加量的提高而增加。对不同还原时间的还原渣进行XRD分析,结果表明,还原过程能够粗略地分为3个阶段:MgAl2O4和Ca12Al14O33的形成阶段;CaAl2O4的生成阶段;CaAl4O7的形成阶段。根据动力学模型将获得的实验数据分为3部分,这3部分的活化能分别为98.2、133.0和223.3 kJ/mol。     

Effect of antimony doped tin oxide on behaviors of waterborne polyurethane acrylate nanocomposite coatings

A multi-functional waterborne polyurethane acrylate (WPUA) nanocomposite coating was prepared through introducing the acrylate groups into the end of the polyurethane main chains and then modified by antimony doped tin oxide (ATO) nanoparticles by ultrasonic dispersion. Structural and morphological features of coatings were assessed using Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and a 3D measuring laser microscope. Performance of the coatings was evaluated using water resistance studies, thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA) and mechanical tests such as tensile strength, elongation at break. The data showed that the WPUA/ATO coatings possessed good mechanical properties and thermal stability. The UV-visible-near infrared (UV-VIS-NIR) spectra results suggested that the WPUA/ATO coatings could absorb near infrared radiation so that it would prevent heat transmission and heat diffusion effectively.     

Synthesis of crosslinked polystyrene particles by seeded batch polymerization with monomer absorption

A highly crosslinked, monodispersed polystyrene(PS) particle was prepared by a seeded batch dispersion polymerization with a monomer absorption method. Prior to polymerization, 1.9 μm monodispersed PS seed particles were treated under an optimum condition of monomer absorption. The effects of divinylbenzebe(DVB) concentration and polymerization temperature were examined for styrene(in PS seed)/styrene(in the second stage) mass ratio of 1:1 in the medium range of EtOH/water mass ratio of 100/0-80/20 and 2.3 μm uniform crosslinked PS particles containing 15%-20% (mass fraction) DVB were prepared at 60-70 °C. The results show that monomer absorption before the second stage of polymerization is more effective to prepare highly crosslinked monodispersed PS particles.     

Curing mechanism of furan resin modified with different agents and their thermal strength

The curing mechanism of furfuryl alcohol and urea-formaldehyde furan resins was investigated using infrared spectroscopy (IR) technique. The curing productions of urea-formaldehyde furan resins modified with different agents (i.e. sorbitol, polyester poiyol, phenol and acetone) and the productions of incomplete curing were characterized by differential thermal analysis (DTA) and thermal gravity analysis (TG). The results indicate that except for polyester polyol, the other modifiers have little effect on the thermal strength of urea-formaldehyde furan resin. Furthermore, the thermal strength can be improved at a temperature of higher than 550℃.     

Antibacterial activity of silver surface modified polyethylene terephthalate by filtered cathodic vacuum arc method

Silver (Ag) modified polyethylene terephthalate (PET) surface by filtered cathodic vacuum arc (FCVA) technique is performed. The structure and component of the modified surface are characterized by X-ray photoelectron spectroscopy (XPS) and the cross-section is observed by scanning electron microscope (SEM). The results show that a 4-5 μm silver layer is formed on the PET surface. The results of the colony forming units (CFU) plate counting in vitro indicate that the adhesion of Staphylococcus epidermidis (SE) to PET is suppressed by silver coating. The adhesion efficiency of SE on the modified surface is only about 25% of the untreated PET surface. The interfacial free energy of adhesion (ΔF_Adh) of SE onto the silver coating deposited on PET is + 8.6 mJ/m², and this means that bacterial adhesion is energetically unfavorable. The releasing rate of silver ions from the PET modified by silver FCVA is 0.12 μg/mL during 2 h. The release of antibacterial silver ion may be another reason of less SE adhered to the PET surface modified by Ag FCVA. The release of lactate dehydrogenase (LDH) was used to evaluate the immediate toxicity of the PET modified by silver FCVA method. It is showed that this modified surface has low toxicity.     

Adsorption behavior and mechanism of amino methylene phosphonic acid resin for Ag（ Ⅰ ）

1 Introduction Many efforts have been made on using ion exchange resin to separate and concentrate certain metal cations [1?11]. However, less research for using it to adsorb noble metal Ag(Ⅰ), and much less research for commercializa- tion has been don…     

四点弯曲法测量钨材料韧脆转变温度及其与其他测试方法的比较研究

针对聚变装置中钨材料的性能评价问题,采用四点弯曲试验(4PBT)方法对钨材料的韧脆转变温度(DBTT)进行了测试和分析.首先,基于对四点弯曲过程的应变率和强度随温度变化的分析获得了商用轧制纯钨的DBTT.结果 表明,用标准四点弯曲法测得的工业轧制纯钨的DBTT值在150℃以下,低于相同材料的拉伸试验和冲击试验的测量值....     

反应火焰喷涂TiC/Fe复合涂层组织及形成机理

以TiFe粉和碳的前驱体（石油沥青）为原料通过前驱体碳化复合技术制备了Ti-Fe-C系反应喷涂复合粉末,并用普通火焰喷涂技术制备了TiC/Fe陶瓷金属复合涂层.观测了喷涂粉末、淬熄实验获取的飞行粒子以及涂层的形态、相和组织结构.结果表明：前驱体碳化复合Ti-Fe-C系喷涂粉末有非常紧密的结构;可有效的解决反应喷涂过程中原料粉末分离的问题.在反应火焰喷涂过程中,每一个喷涂粉末颗粒构成独立的微小反应单元,原料之间反应充分.在整个喷涂过程中喷涂粉末经历了熔化扩散、物相形成、碰撞后快速凝固三个阶段.所得涂层由TiC和Ti2O3共生聚集片层和细小TiC颗粒弥散分布于金属基体所形成的内晶型复合强化片层交替叠加而成.