Effects of heat treatment on mechanical properties and microstructure of tungsten fiber reinforced grey cast iron matrix composites

In this study,grey cast iron matrix composites reinforced by different volume fractions of tungsten fibers(Vr=0.95%,1.90%,2.85%,3.80%)were investigated in as-cast and under the heat treatment temperatures of 1,000℃and 1,100℃.The microstructure and mechanical properties of the composites were analyzed and tested by means of SEM,micro-hardness tester and three-point bend testing.The results show that with increasing of the volume fraction of tungsten fibers,the composites reinforced by the tungsten fiber have higher flexural strength and modulus than that of cast iron without reinforcement,and the flexural strength increases with the increasing of heat treatment temperatures.Due to diffusion reaction between matrix and reinforcing phases,the process of heat treatment,the number of graphite flakes in the matrix seemingly becomes lower;and some hard carbide particles are formed around the residual tungsten fibers.Not only does the hardness of both matrix and reinforcement change tremendously,but also the region of reinforcement is also extended from the original 0.11 mm to 0.19 mm in radius.

A Fiber Optic Sensor for Determination of 2,4-dichlorophenol based on Iron(Ⅱ) Phthalocyanine Catalysis

A new fi ber optic sensor based on the oxidation of 2,4-dichlorophenol（DCP） catalyzed by iron（II） phthalocyanine（Fe（II）Pc） was developed for the determination of DCP. The optical oxygen sensing fi lm containing fl uorescence indicator Ru（bpy）3Cl2 was used to detect the consumption of oxygen in solution. Moreover, a lock-in amplifier was used to determine the lifetime of the sensor head by detecting its phase delay change. The results reveal that the sensor has a linear detection range of 1.0×10^-6- 9.0×10^-5 mol/L and a response time of 5 min. The sensor also has high selectivity, good repeatability and stability. It can be used effectively to determine DCP concentration in real samples.

Improving Electrochemical Performance of Cellulose Fiber-based Supercapacitor Electrode Using Polypyrrole-wrapped Iron Oxyhydroxide

Polypyrrole(PPy)@cellulose fiber-based composites have been widely investigated as electrode materials for use in flexible supercapacitors.However,they cannot readily provide high specific capacitance and cyclic stability owing to their inherent drawbacks,such as high resistance,Weber impedance,and volume expansion or collapse during charging/discharging.In this study,iron oxyhydroxide(FeOOH)is incorporated in the abovementioned composite to decrease the equivalent series resistance,charge transfer resistance,and Weber impedance,thereby enhancing electron transfer and ion diffusion,which results in superior electrochemical performance.The PPy-wrapped FeOOH@cellulose fiber-based composite electrode with the molar ratio of FeSO_(4) to NaBH4 of 1∶1 exhibits a high specific capacitance of 513.8 F/g at a current density of 0.2 A/g,as well as an excellent capacitance retention of 89.4% after 1000 cycles.

Iron Fibers Arrays Prepared by Electrodepositing in Reverse Liquid Crystalline

Ordered iron fiber arrays were electrodeposited on the surface of zinc foils using ＂FeSO4 solution-sodium caprylate-Decanol＂ 3-component reverse hexagonal liquid crystal as soft templates. The structure of the soft templates and the synthesized iron ,fibers were characterized by polarizing microscopy, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersive X-ray microanalysis etc. The experimental results shou that the synthesized iron fibers with a crystal phase grew up in the form of fiber clusters of about 200 nm along the direction perpendicular to the cathode surface. Each cluster was composed of several tens of fibers. The fibers had almost the same length of more than 10μm with a diameter of about 50 nm.

Effect of Grinding Techniques on Absorbing Characteristics of Short Iron Fibers

Microwave-absorbing properties of iron fibers can be adjusted by their aspect ratio. This paper presents several modification techniques for grinding long iron fibers to a suitable aspect ratio. The grinding instruments include pulsator, jet mill and muller. The aspect ratio distribution, microstructure, electromagnetic parameter and reflectivity of the samples were analyzed and discussed in detail. The results show that the fractions of 5〈aspect ratio〈40 for the three methods are 69.03%, 81.11% and 80.2% , respectively, that is, suitable short iron fibers can be obtained by the jet mill and muller. Furthermore, the short iron fibers milled by jet mill and muller have better absorbing propterties than those obtained by the pulsator under the same condition. Therefore, their microwave absorption properties can be improved by regulating the electromagnetic parameters with grinding.

Effects of Steel Fibers and Iron Filings on Thermal and Mechanical Properties of Concrete for Energy Storage Application

An experimental study on the thermal properties of iron filings and steel-fiber-reinforced concrete for solar/thermal energy storage application is presented in this report. It takes into account the results of measurements of thermal conductivity, thermal resistivity, thermal diffusivity and the results of compressive strength, density as well as energy storage capacity calculated from the knowledge of the above measured parameters. The experimental testing method is described as well: based upon the linear heat source theory, it requires the use of a special probe to be inserted into the sample. The experimentation was forwarded to test concrete aggregate mixtures with three different sizes and same quantity of steel fibers;two different quantities of iron filings and one plain concrete. The measurements were carried out from the pouring time of cubic samples and were ended up when hardened conditions were achieved. The results indicate that the steel fibers and iron filings have influence on the thermal and mechanical properties of the concretes tested, thus the iron filings and steel fibers reinforced concrete is suitable for better solar/thermal energy storage due to an increase in storage capacity over plain concrete.

铁尾矿-钢纤维双掺混凝土制备及性能研究

铁尾矿长期堆积在尾矿库造成资源浪费和环境破坏,研究铁尾矿-钢纤维混凝土力学性能对开发利用铁尾矿具有重要意义。在混凝土中掺入铁尾矿和钢纤维,研究不同材料配比下混凝土的抗压强度变化。结果表明:铁尾矿掺量过低,生成的胶状聚合物较少,黏结作用较弱,铁尾矿掺量过高会导致混凝土含水量过高,均会降低混凝土抗压强度;钢纤维对混凝土抗压强度具有提升作用;氢氧化钠掺量与水胶比主要影响胶状聚合物的形成,分布均匀、充足的胶状聚合物可有效连接水泥基体和钢纤维,增强混凝土抗压强度;铁尾矿-钢纤维混凝土最优配比为铁尾矿掺量40%、45 mm长度钢纤维体积掺量2%、氢氧化钠掺量40%、水胶比0.2。

铁粉/碳纤维增强树脂复合材料的制备 及脆化损伤研究

将偶联剂改性纳米铁(Fe)粉与预处理后的碳纤维混合,浸润于环氧树脂基料中,经过搅拌混合制备纳米Fe粉/碳纤维增强树脂复合材料,研究了复合材料在高温老化、水浸老化环境下的脆化损伤行为。结果表明:树脂受到高温老化和水浸泡老化后会出现脆化损伤,碳纤维和纳米Fe粉加入会对该损伤有一定抑制;加入质量分数为4.0%的纳米Fe粉后,随着高温老化时间延长,碳纤维质量分数为3.0%的纳米Fe粉/碳纤维增强复合材料的拉伸强度、断裂韧性下降幅度较小,同时脆化损伤后树脂与纳米Fe粉、碳纤维仍结合紧密;碳纤维质量分数为3.0%、纳米Fe粉质量分数为4.0%的纳米Fe粉/碳纤维增强复合材料经水浸老化后,断裂韧性仍旧保持较高水平。

钢纤维-海泡石纤维优化铁尾矿砂-石英砂混合砂浆性能试验研究

为了在保证经济性的同时改善铁尾矿砂-石英砂混合砂浆的性能,选用钢纤维、海泡石纤维优化混合砂浆,研究了钢纤维、海泡石纤维单掺和以不同比例混掺对混合砂浆工作性能、力学性能和自然干燥收缩率的影响。结果表明,在单掺情况下,海泡石纤维对流动性的负面影响高于钢纤维,两种纤维分别以合适掺量掺入混合砂浆中,钢纤维对抗折强度和28 d自然干燥收缩率的改善效果优于海泡石纤维,而海泡石纤维对抗压强度的改善效果更佳;钢纤维-海泡石纤维以0.50%-1.0%和0.75%-1.0%组合混掺对矿浆力学性能和干燥收缩改善效果最佳。从性能改善效果和经济性角度综合考虑,确定了最优纤维掺量组合,即钢纤维、海泡石纤维掺量分别为0.50%、1.0%。在此掺量组合下,混合砂浆3 d、7 d和28 d抗折强度分别提升了15.8%、13.0%和12.5%,混合砂浆3 d、7 d和28 d抗压强度分别提升了16.2%、14.7%和13.9%,28 d自然干燥收缩率降低了32.8%,且经济性良好,每吨混合砂浆仅增加28.8元左右的成本。

PVA-铁尾矿砂混凝土抗折性能研究

为实现固废再生利用,将铁尾矿砂部分替代细骨料并掺入PVA纤维,制备出具有良好和易性的PVA-铁尾矿砂混凝土,通过标准抗折试验研究了不同铁尾矿砂替代率与PVA纤维掺量对混凝土抗折性能的影响。研究表明,PVA纤维掺量为0%和0.1%(质量分数,下同)时试件发生贯通型开裂脆性破坏,而PVA纤维掺量为0.2%和0.3%的试件破坏时裂缝宽度明显减小且未贯通。当铁尾矿砂替代率为30%、PVA纤维掺量为0.3%时,试件跨中挠度和抗折强度均达到最大值,较普通混凝土分别提高了22.04%和6.57%。当铁尾矿砂替代率超过30%时试件抗折强度和跨中挠度会显著下降。与单掺PVA纤维相比,混掺PVA纤维与铁尾矿砂的试件变形能力增强更明显。由XRD谱可知,30%铁尾矿砂替代率下试件中C-S-H凝胶与钙矾石生成量最多,能显著提高材料强度。

中国玻璃纤维铝质原料开发现状及趋势

玻璃纤维原料主要包括铝质材料、钙质材料、镁质材料等,其中铝质原料约占65%,国内主要选用叶蜡石。随着工业的发展,优质叶蜡石资源减少。为寻找适宜的铝质原料,本研究对国内3种铝质原料叶蜡石矿、高岭土矿、白泡石矿典型矿床进行特征分析,并梳理了3种矿石干法除铁的技术研究现状,旨在拓展玻璃纤维原料选择范围,为解决国内优质玻璃纤维原料逐渐匮乏的困扰提供思路,同时为铝质原料发展方向提供参考。

层间熨平法增强熔丝制造CF/PEEK复合材料的力学性能

为减小熔丝制造(FFF)3D打印碳纤维增强聚醚醚酮(CF-PEEK)复合材料的孔隙率,提高其力学性能,提出一种层间熨平方法,即打印完一层后,喷嘴不挤出材料,并再次在这一层表面压过“熨平”。采用FFF工艺制备了CF/PEEK复合材料试样,通过单因素试验研究了扫描间距和层间熨平角度对CF/PEEK复合材料力学性能的影响。使用微米X射线三维成像系统对试样的内部孔隙缺陷进行表征。结果表明,当扫描间距为0.3 mm,纤维质量分数为10%时,无熨平CF/PEEK试样的孔隙率为1.91%,拉伸强度为78.5 MPa,弯曲强度为111.2 MPa。采用层间熨平法可以显著降低CF/PEEK复合材料试样的孔隙率,提高其力学性能。0°和90°熨平后,扫描间距为0.5 mm的CF/PEEK试样的孔隙率分别降低了74.08%和72.48%,拉伸强度分别提高了49.89%和41.98%,弯曲强度分别提高了20.66%和15.99%。当纤维质量分数为10%时,扫描间距0.3 mm的CF/PEEK试样的力学性能最佳,0°熨平的拉伸强度为90.9 MPa,90°熨平的弯曲强度为126.1 MPa。研究表明,层间熨平是一种降低孔隙率和提高力学性能的简单而有效的方式。

镍铁矿渣纤维对SMA-13沥青混合料高温稳定性的影响研究

纤维沥青混凝土具有优异的抵抗变形能力,耐久性较好,受到业内广泛关注。文章选用一种新型矿物纤维——镍铁矿渣纤维作为SMA-13混合料的纤维改性剂,通过马歇尔试验和车辙试验对改性后SMA-13沥青混合料的高温稳定性进行研究。结果表明:1#镍铁矿渣纤维掺量为0.4%时,对SMA-13沥青混合料马歇尔模数的提升效果最为明显,其改性效果优于木质素纤维;1#和3#镍铁矿渣纤维均可较好提升SMA-13沥青混合料的车辙动稳定度,且掺量达到0.4%以上时效果略优于木质素纤维的改善效果。综合高温性能测试结果,1#镍铁矿渣纤维提升SMA-13混合料高温性能的效果最佳,其最优掺量为0.4%。

棉纤维基碳@FeP复合材料的制备及储钠性能研究

废弃纺织品转化为电化学储能材料引起人们的广泛关注,在碳材料中掺杂渡金属化合物作为钠离子电池负极材料具有更佳的电化学性能。本实验以废旧棉织物为碳源,硝酸铁作为催化剂,经过高温碳化得到了棉纤维基碳化铁(CFC)的复合材料,然后通过气相磷化的方法将CFC转化成棉纤维基石墨碳包覆的磷化铁复合材料(CFGC@FeP)。本文中对CFC、CFGC@FeP进行储钠性能分析,从而研究磷化铁掺杂对钠离子电池硬碳负极的影响,结果表明:将CFC、CFGC@FeP组装成半电池,可以发现CFGC@FeP具有更佳的首次库伦效率和倍率性能。CFGC@FeP在0.05 A·g^(-1)电流密度下充放电时ICE可以达到87.6%,ICE远高于CFC。同时,可以看到CFGC@FeP在5 A·g^(-1)进行充放循环500圈后,比容量为130 mAh·g^(-1),容量保持率达到96%,倍率性能良好。

纤维增强铁尾矿砂水泥基材料力学性能和孔隙结构实验

这是一篇陶瓷及复合材料领域的论文。本文详细研究和讨论了铁尾矿砂和PVA纤维对水泥基复合材料抗压强度、四点抗弯强度、弯曲韧性、孔隙结构。此外,建立了抗压强度与四点抗弯强度之间换算关系。结果表明:铁尾矿砂掺入对力学性能有增强效果,并且这种增强效果随着取代率的增加呈现先增加后减小趋势。而PVA纤维掺入后力学性能进一步提升,并且呈现出良好韧性。此外,铁尾矿砂取代率40%和PVA纤维复合时,基体内部孔隙明显降低。因此,认为当铁尾矿砂取代率为40%与PVA纤维结合,水泥基复合材料拥有良好的力学性能。

热压法制备MIL-100(Fe)/ACF复合材料及其对染料的光催化脱色

以七水合硫酸亚铁为金属盐,均苯三甲酸(H3BTC)为配体,活性炭纤维(ACF)为基材,采用热压法制备了MIL-100(Fe)/ACF复合材料。以活性黑KN-R染料为脱色对象,通过正交试验优化了MIL-100(Fe)/ACF复合材料的制备工艺:七水合硫酸亚铁与H3BTC的物质的量之比为1.5∶1、热压温度为150℃、热压时间为40 min。利用SEM、FT-IR、XRD表征手段,证明MIL-100(Fe)成功负载到ACF上。研究了复合材料在不同条件下对染料的脱色性能,结果表明:随着染液中H2O2添加量的增加,脱色率提高,但当H2O2加入量超过0.16 mL/L后,脱色率变化不大。复合材料对不同染料的脱色效果不同,对活性黑KN-B和罗丹明B的脱色率超过96.0%,对活性红3BS的脱色率达到90.0%以上,对活性艳蓝KN-R的脱色率仅为65.6%。重复使用4次后,对活性黑KN-B染液的脱色率为75.4%。

铁尾矿与纤维改良的混凝土楼板力学性能及强度研究

为研究铁尾矿混凝土在装配式组合楼板中的工程性能,利用不同铁尾矿砂替代石英砂作为细骨料,制备了新型纤维铁尾矿混凝土,并对其开展了立方体抗压、劈裂抗拉和抗弯强度试验。结果表明,利用铁尾矿砂部分替代石英砂制备新型混凝土具备高度可行性,当铁尾矿砂替代率为40%、PVA纤维掺量2%时,新型纤维改良铁尾矿混凝土的综合性能最佳,此时,其立方体抗压强度、劈裂抗拉强度、抗弯强度均取得最大值,分别为37.15、3.02和4.58 MPa,较普通混凝土分别提升23.22%、54.87%和29.01%。研究成果为新型铁尾矿混凝土在装配式组合楼板中的设计和应用提供了借鉴作用。

Highly active Fe_(7)S_(8) encapsulated in N-doped hollow carbon nanofibers for high-rate sodium-ion batteries

Nanostructured iron sulfides are regarded as a potential anode material for sodium-ion batteries in virtue of the rich natural abundance and remarkable theoretical capacity.However,poor rate performance and inferior cycling stability caused by sluggish kinetics and volume swelling represent two main obstacles at present. The previous research mainly focuses on nanostructure design and/or hybridizing with conductive materials.Further boosting the property by adjusting Fe/S atomic ratio in iron sulfides is rarely reported.In this work,Fe_7 S_8 and FeS_2 encapsulated in N-doped hollow carbon fibers(NHCFs/Fe_7 S_8 and NHCFs/FeS_2) are constructed by a combined chemical bath deposition and subsequent sulfidation treatment.The well-designed NHCFs/Fe_(7) S_(8) electrode displays a remarkable capacity of 517 mAh g^(-1) at 2 A g^(-1)after 1000 cycles and a superb rate capability with a capability of 444 mAh g^(-1) even at 20 A g^(-1) in etherbased electrolyte.Additionally,the rate capability of NHCFs/Fe_(7) S_(8) is superior to that of the contrast NHCFs/FeS_(2) electrode and also much better than the values of the most previously reported iron sulfide-based anodes.The in-depth mechanism explanation is explained by further experimental analysis and theoretical calculation,revealing Fe_(7) S_(8) displays improved intrinsic electronic conductivity and faster Na^(+) diffusion coefficient as well as higher reaction reversibility.

铁碳纤维人工水草对污染河湖微生物挂膜的影响

针对水体强化净化过程中碳纤维人工水草表面能低、微生物附着时间长、挂膜启动慢的问题,利用废铁和碳纤维水草组合构建了铁碳纤维人工水草(ICF),以重污染地表水为原水,在阶段曝气的条件下进行了强化挂膜实验研究。结果表明,与碳纤维人工水草相比,铁碳纤维人工水草上生物膜的附着性能显著提升,生物膜的挂膜率由125.1%增加至133.0%,形成生物膜的团簇结构尺寸明显更大。启动期末(21 d)生物膜胞外聚合物中多糖、蛋白及蛋白/多糖比,分别由53,71 mg/gVSS、1.33改变为39,106 mg/gVSS、2.71。铁碳材料对假单胞菌属细菌的富集和筛选,改善了细菌的运动能力,促进了细菌分泌胞外聚合物的行为,此外,微生物活性功能基因在ICF中高度表达,提升了铁碳纤维材料表面微生物附着性能。

碳纤维负载二元锆铁氧化物复合材料对水中锑的吸附研究

金属氧化物吸附剂常被用来处理废水中的锑,然而因其呈粉末状,存在分离回收难问题。采用溶剂热法制备了一种新型的二元锆铁氧化物粉末材料,将其负载到碳纤维表面而获得锆铁-碳纤维复合材料(ZF@CF)并用于水中锑的吸附研究。利用扫描电镜(SEM)和红外光谱(FT-IR)对制得的ZF@CF复合材料进行形貌和结构表征,结果显示锆铁氧化物粉末材料可有效地负载于碳纤维表面,其表面拥有丰富的—OH功能基团。系统研究了溶液pH、不同初始浓度、接触时间和温度等因素对ZF@CF吸附锑效果的影响。结果表明:该材料对Sb(Ⅲ)和Sb(Ⅴ)的吸附过程符合Langmuir模型和准二级动力学模型,吸附量分别为21.65mg/g和14.96mg/g,高于碳纤维材料本身。这表明ZF@CF复合材料具有结构稳定、易回收的特点,对水中锑具有良好的吸附效果,是一种具有良好潜力的除锑吸附剂。