抗折剂对混凝土性能的影响研究

分析了当前普通水泥混凝土路面裂缝和断板的问题,在此基础上验证了不同掺量抗折剂的混凝土与基准混凝土的抗折强度和抗裂性能,随着抗折剂掺量的增加,混凝土抗折强度先增大后降低,当掺量3%时,混凝土抗折性能最大;通过应力强度因子分析验证,抗折剂掺量3%时,混凝土抗裂应力增进率达到最大值。     

金属结合剂金刚石工具胎体耐磨性随烧结温度变化的研究

文章重点研究了一种铁基金属结合剂金刚石工具胎体耐磨性随烧结温度升高的变化规律.通过对胎体耐磨性、硬度、抗弯强度、抗冲击强度等一系列物理性能指标的测定,以及利用该胎体制成的锯片做对比试切试验结果分析,得出以下结论:(1)铁基结合剂胎体耐磨性随温度的升高呈现3个阶段的规律变化;(2)测定出了耐磨性最佳时烧结温度范围.将该项研究成果应用于生产中可以大幅度地降低金属结合剂金刚石工具的单位产出能耗,符合国家节能减排的经济增长方式.     

金属粉料预压块的还原处理对金刚石工具胎体性能的影响

以铁基粉末为金刚石工具胎体材料,采用“预压一还原一热压烧结”和“预压一热压烧结”工艺制备烧结体.采用氧含量测定仪检测了预压块和还原块的含氧量,采用扫描电子显微镜(SEM)观察了烧结体的微现形貌,研究了铁基粉末预压块的还原处理对胎体体积密度、洛氏硬度、抗弯强度和耐磨性等性能的影响.试验结果表明:经过还原处理后,还原块的氧含量明显降低,获得的烧结体组织更加致密,其性能也优于未处理过的.     

隔离剂对子午线轮胎胎体胶性能的影响

研究粉状隔离剂和膏状隔离剂对子午线轮胎胎体胶性能的影响。结果表明:粉状隔离剂溶液和膏状隔离剂溶液的分散性和稳定性无明显差异;两种隔离剂对胎体胶的硫化特性、物理性能及成品轮胎性能影响均很小;粉状隔离剂的隔离防粘效果优于膏状隔离剂,使用成本低于膏状隔离剂。     

两种不同造孔剂对粉煤灰-黄土基支撑体性能的影响

以粉煤灰、黄土为混合骨料,甲基纤维素作粘结剂,采用挤压成型法和固态粒子烧结法制备陶瓷膜支撑体,探究淀粉和聚甲基丙烯酸甲酯两种造孔剂对支撑体的孔隙形成、抗折强度、酸碱腐蚀率、物相组成、显微结构及纯水通量等性能的影响。结果表明,聚甲基丙烯酸甲酯添加量为15%时,各项参数基本优于淀粉添加量为10%时支撑体的各项表征,并且其成品内部孔隙均一,分布较为均匀,孔径均在6μm左右,酸碱质量损失率分别为0.24%/0.19%,孔隙率为35%,抗折强度为30 MPa,支撑体纯水通量为9 523.28 L/(m²·h·MPa)。     

隔离剂AT-JG对全钢子午线轮胎胎体胶性能的影响

研究国产粉状隔离剂AT-JG对全钢子午线轮胎胎体胶性能的影响,并与进口粉状隔离剂ET进行对比。结果表明:隔离剂AT-JG的水溶液分散性和稳定性好,其隔离和防粘效果较好,优于隔离剂ET;隔离剂AT-JG对胶料硫化特性和物理性能的影响较小,与隔离剂ET相当。隔离剂AT-JG具有优异的使用性能。     

隔离剂G-28对全钢子午线轮胎胎体胶性能的影响

试验研究隔离剂G-28对全钢子午线轮胎胎体胶性能的影响,并与进口同类产品进行对比。结果表明,在胎体胶上粘挂隔离剂,可增大胶料的MH,加快硫化速度;提高硫化胶的粘合性能,对其它物理性能影响不大。粘挂隔离剂G-28的胶料性能与粘挂进口产品的胶料基本相当。     

石墨对金属结合剂金刚石磨具性能的影响

采用正交实验法,通过测定金属结合剂金刚石磨具的磨耗比,结合考虑磨具的力学性能,综合地研究了不同石墨种类、粒度和含量对金属结合剂金刚石磨具性能的影响。实验结果表明：当添加质量分数为3wt%、粒度为80目的鳞片状石墨时,金属结合剂金刚石磨具的磨耗比最大,达到206.62,并且力学性能良好,锋利度高。故其综合性能良好,具有较高的使用价值。     

NaCl对多层焊接陶瓷锯片性能的影响

针对多层焊接切割陶瓷锯片细粒度金刚石如何提升速度进行了研究,通过分析多层焊接陶瓷锯片配方性能影响因素分析,提出了增加一定量的NaCl弱化胎体,从而增加刀头的自锐性和排屑能力,提高锋利度,最后通过实验验证了此方法的有效性。     

含水率对固态激发剂制备地质聚合物显微结构与性能的影响

主要研究了固态激发剂制备地质聚合物样品中含水率对显微结构与抗折强度的影响,并对样品进行了XRD、SEM及EDS表征。结果表明：含水率为11%,混合料静置12 h时,抗折强度最大值为31.62 MPa。继续延长静置时间,样品抗折强度基本无变化;含水率过少或过多,均会引起样品结构中微裂纹的产生,使样品抗折强度下降。随静置时间的延长,养护后Na型针沸石相的特征衍射峰逐渐增强,形成一种硅铝摩尔比为1.13的单硅铝链状结构,其通过聚合生长方式朝不同方位穿插生长,最终形成针状聚集体形貌的沸石晶体,增大样品的抗折强度。     

典型金属离子冲击对膜生物反应器运行的影响

对进水中Na+,Ca2+和Fe3+冲击对膜生物反应器(MBR)运行的影响进行了探讨。实验结果表明:进水中3种金属离子冲击对MBR去除COD影响较小,适量质量浓度的Fe3+有利于NH3-N的去除,然而Na+与Ca2+对NH3-N去除影响不明显;进一步研究发现进水中Na+将引起反应器内上清液(SMP)质量分数上升,从而增加膜过滤阻力;进水中Fe3+质量浓度为50 mg/L时显著降低本体溶液中SMP质量分数,有利于减缓膜污染,而当Fe3+质量浓度为150 mg/L时SMP质量分数升高,使膜污染率升高;研究中也发现进水中Ca2+在50或150 mg/L时都可有效地减缓膜污染,进水中金属离子质量浓度与EPS中TB质量分数关系密切。     

酞菁铁对MH/Ni电池浮充性能的影响

研究了酞菁铁(FePc)对金属氢化物-镍电池浮充性能的影响。添加适量FePc的电池具有较好的浮充浮放性能,其中添加1mgFePc的电池显示了最好的充电效率和循环性能;2000次浮充以后其内压升高速度也最低。     

金属硫酸盐与氧化物助剂对SCR脱硝催化剂性能的影响

通过分步浸渍法制备了一系列以碱土金属或过渡金属为助剂,低钒含量的V-M_x(SO₄)_y-W/Ti及V-M_xO_y-W/Ti催化剂,对负载相同金属离子硫酸盐及氧化物的催化剂性质进行了对比考察。通过选择性催化还原(SCR)反应对催化剂进行活性评价,结果显示,负载某金属硫酸盐比相应氧化物助剂的催化剂活性好。负载钴离子的催化剂具有良好的低温活性,进而对负载钴离子的催化剂进行了抗硫抗水性能测试,并借助XRD、NH₃-TPD、H₂-TPR、TG、BET对负载不同金属硫酸盐及氧化物助剂的催化剂进行了表征,揭示了活性好的催化剂(如负载CoSO₄的催化剂)通常具有较多的表面酸及较好的低温还原能力。     

Influence of aluminum alloys on protection performance of metal matrix composite armor reinforced with ceramic particles under ballistic impact

In this research, the ballistic performance of three series of aluminum alloys in the ceramic-reinforced metal matrix composite plates is investigated for protecting against 7.62 × 39 mm bullet. Twenty seven numerical models of the target combinations are provided by ABAQUS FE code to determine the best armor characteristics and confirmed by three experimental ballistic tests. The parameters which considered in this study are aluminum alloys: AA6061, AA7075 and AA5083 as the matrix, alumina ball weight percentages include 15%, 30% and 45% as reinforcements and the target thickness 20, 25 and 30 mm and the effects of these parameters on the ballistic behavior of the composite armor like depth of penetration, residual velocity, kinetic energy and erosion of the projectile are investigated. The results show that AA6061 is the weakest aluminum alloy for ballistic applications and AA5083 is the best choice to use as the aluminum matrix. Also, it's found that the optimum design of aluminum matrix composite armor against 7.62 × 39 mm projectile is AA5083 with 25 mm thickness and 30% alumina.     

Fatgiue behavior of metal matrix nanocomposites

Light-weight high-strength composites (particularly with aluminum and magnesium base alloys) have principal applications in a wide variety of fields ranging from automotive and aerospace structures to medical and energy applications wherein the materials undergo both static and dynamic (fatigue) loading conditions. Conventional metal matrix composites (MMCs), i.e. those filled by micro-sized reinforcements, have usually poor ductility and insufficient mechanical performance made them, therefore, unreliable to be used in some critical applications. Instead, those composites strengthened by nano-sized reinforcing agents, namely metal matrix nano-composites (MMNCs), have newly been developed in order to boost the mechanical properties. The current paper aims to study the fatigue behavior of the MMCs with a particular attention on recent investigations made on MMNCs. It is believed that the materials selection, microstructural features, manufacturing and processing parameters, etc. have a dominant influence on the fatigue response of MMNCs.     

Wear behavior of metal matrix nanocomposites

Metal matrix nanocomposites (MMNCs), a unique class of metallic materials having superior mechanical, chemical, thermal or tribological properties, are commonly used in critical applications Those light-weight aluminum and magnesium alloys usually working in harsh wear conditions are susceptible to surface attacks. Although a lot of investigations have already been performed on those conventional composites reinforced by micro-particles, the wear behavior of the nanocomposites has not yet been fully understood. The surface properties associated with MMNCs are presented in this paper focusing mostly on manufacturing & processing routes, nano-particles as well as the dominant wear mechanisms. Studying wear behavior of MMNCs shows that no quantitative comparison of different existing studies is available as it is aimed to be done in the present review. To this end, wear reports have been categorized and discussed wherein the following results has been obtained: (i) it is found that ceramics reinforced composites usually exhibit a relatively better wear resistance behavior compared to those filled by carbon-based nanomaterials, (ii) hybrid MMNCs with two or more reinforcement types are promising materials to improve the surface resistance, particularly when the combination of ceramic and carbon-based particles are employed, (iii) solid-state processes like powder metallurgy usually provide superior wear resistance as compared to those liquid processing methods like casting, (iv) the use of smaller reinforcement size may almost always result in superior response, (v) abrasion is the most governing wear mechanism amongst the abrasion, adhesion and delamination mechanisms being frequently observed in MMNCs. A comprehensive review is made with particular attention on the composites reinforced by nano-sized reinforcing agents in order to evaluate the current research activities, discuss the pitfalls and provide a roadmap for future endeavors. It is believed that still countless research opportunities exist in order to fill the existing voids and fulfill the challenges with MMNCs.     

混炼机类型对新型白炭黑-硅烷混炼加工性能的影响

综述了混炼机类型对白炭黑一硅烷混炼加工性能的影响。通过使用现有硅烷如Si69与新型硅烷VP Si363的胶料对比,证明新型硅烷VP Si363的胶料其加工性能在很大程度上取决于可用的混炼设备;对于啮合型转子捏合机和切线型转子捏合机,其整体加工行为与性能必须保持平衡,从而实现VP Si363胶料的最佳结果。     

Effect of nanofillers on selectivity of high performance mixed matrix membranes for separating gas mixtures

Techniques for separation of gas mixtures obtained from various sources, such as effluents from industries, and biogas, have always fascinated researchers. The advent of mixed matrix membranes (MMMs) has opened up a new window of opportunity for developing membranes coupled with flexibility, processability, and permeability of polymers and selectivity of inorganic nanomaterials. This review is a detailed overview of the effect of various nanofillers on the separation performance of MMMs including the major factors affecting the perm-selectivity and possible solutions for overcoming the emerging challenges. The paper also presents contemporary approaches for cost-effective implementation of MMMs. Methodologies for designing MMMs with improved interfacial morphology to exploit their full potential in tailoring the selectivity efficiency are also discussed in detail. This review can act be a guideline for the future development of high-performance MMMs for industrial applications without compromising long-term separation performance, durability, and stability to processing conditions.     

Effect of solvents on performance of polyethersulfone ultrafiltration membranes: Investigation of metal ion separations

The new polyethersulfone (PES) based ultrafiltration membranes were formed using a two stage process of dry and wet phase inversion in non solvent coagulation bath. The effects of three different solvents such as, N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and Dimethyl sulphoxide (DMSO) of 82.5% and 85% concentrations on the performance of final membranes were extensively investigated. Scanning electron microscopy (SEM) image results proved that PES membranes with an asymmetric structure were successfully formed. The number of pores formed on the top layer of PES membranes using above-mentioned three solvents was the result of the combined effect of the thermodynamic properties of the system (composition, concentrations, and phase behaviour) and membrane formation kinetics, whereas, the formation of the macroporous sub layer of those membranes was controlled by the diffusion rate of solvent–nonsolvent. The flux of pure water, membrane resistance, mechanical stability, molecular weight cut-off (MWCO) and separation performance of the PES membranes were studied. Separation of metal ions from aqueous solutions was studied for Ni(II), Cu(II) and Cr(III) using two complexing polymer ligands: polyvinyl alcohol (PVA) and poly(diallyldimethylammonium chloride) (PDDA).The separation and permeate rate (flux) efficiencies of the new membranes are compared using different solvents and different PES/solvent compositions.