磁性指数对铁尾矿水泥基材料特性的影响

为实现铁尾矿代替天然河砂制备水泥基材料的目标,以8种磁性指数的铁尾矿和天然河砂为骨料分别制备了水泥砂浆和混凝土试件。通过测试砂浆的力学性能、试件断面的显微硬度、孔结构参数以及混凝土的抗氯离子渗透性能,分析了磁性指数对铁尾矿水泥基材料特性的影响。试验结果表明：在相同配合比下,铁尾矿砂浆力学性能优于天然河砂砂浆;提高铁尾矿的磁性指数,砂浆力学性能呈现下降趋势,但是磁性指数为40％的铁尾矿砂浆强度仍然较高;当磁性指数为0％时,铁尾矿砂浆界面区显微硬度最高,磁性指数为40％的铁尾矿砂浆次之;磁性指数为0％和40％的铁尾矿砂浆孔隙率较低且无害孔含量更多;通过磁选分离降低铁尾矿的磁性指数,有利于增强铁尾矿混凝土的抗氯离子渗透性能,提高其耐久性。     

Research on the Anticorrosion Coating Under the Paved Layer for Highway Steel Box Bridge Deck

The corrosion of the anticorrosion coating and the defects of the asphalt concrete paved layer have been investigated on long-span steel box bridge decks. The anticorrosion coating lies in the midclle of two entirely different materials： a highway steel box bridge deck and a paved layer, which is used as anticorrosion and waterproof coating for the steel bridge deck. For our study, electrochemical corrosion and pull strength experiments have been selected for the investigation of the corrosion properties of inorganic zinc rich coating, epoxy zinc rich coating and arc sprayed zinc coating. The adhesive strength between the coatings and the panel, and the effect of the coating corrosion on the shear properties of the paved layers including cast asphalt, thermal asphalt mortar, epoxy asphalt and modified asphalt con- crete have been investigated. The results show that the adhesive strength between the coatings and the bridge panel is controlled by the method of pre-processing rust removal. Coating by sandblasting has stronger adhesive strength than coating by shot peening. The results also reveal that shear strength of the paved layer is affected by the corrosion product of zinc coating. The arc sprayed zinc coating has stronger shear strength than zinc rich coatings.     

Effect of laser remelting on the microstructure and corrosion resistance of plasma sprayed Fe-based coating

Fe-based amorphous and nanocrystalline coatings were fabricated by air plasma spraying. The coatings were further treated by laser remelting process to improve their microstructure and properties. The corrosion resistance of the as-sprayed and laser-remelted coatings in 3.5wt% NaCl and 1 mol/L HCl solutions was evaluated by electrochemical polarization analysis. It was found that laser-remelted coating appeared much denser than the as-sprayed coating. However, laser-remelted coating contains much more nanocrystalline grains than the as-sprayed coatings, resulting from the lower cooling rate in laser remelting process compared with plasma spraying process. Electrochemical polarization results indicated that the laser-remelted coating has great corrosion resistance than the as-sprayed coating because of its dense structure.     

Effect of coated PHB on properties of abradable seal coating

As pore-forming materials, the coated polyop-hydroxybenzoate（short for PHB） and h-BN can be applied in the preparation of abradable seal coatings at high temperature. The characteristics of coating such as morphology, thermal stability and composition were studied by SEM, EDS and FTIR. The results show that the modified PHB will change the remained carbon amount, porosity and pore morphology of the coating, which can affect the properties of coatings. If the pore is small enough in uniform distribution, the coating with 5 MPa bond strength, 30-55 HR45Y superficial hardness and certain of carbon can be suitable to well abradability.     

活性瓷釉涂层钢纤维混凝土板动、静力学特性研究

活性瓷釉涂层是近几年才开始系统研究的一项新型钢筋涂层技术.活性瓷釉涂层能够显著增强钢筋与混凝土黏结能力和钢筋的抗腐蚀能力,成本低廉,工艺简单,利于大范围使用.对活性瓷釉涂层钢筋的黏结强度和防腐蚀能力进行了论述,并通过钢纤维混凝土板的动、静力试验,验证了活性瓷釉涂层应用于钢筋混凝土结构防爆中的可行性.研究表明,活性瓷釉涂层能够提高钢筋、钢纤维与混凝土的黏结性能,从而改善结构的整体性,显著增强结构承载能力和抵御爆炸荷载的能力.     

Microstructure and Properties of Graphene Oxide-doped TiO_2 Coating on Titanium by Micro Arc Oxidation

Micro arc oxidation(MAO) coatings doped with graphene oxide(GO) were prepared on pure titanium by adding GO and sodium dodecyl benzene sulfonate(SDBS) into a sodium silicate solution. The as-deposited coatings were comparatively analyzed by scanning electron microscopy(SEM), energydispersive X-ray spectroscopy(EDS) and X-ray diffraction(XRD). The binding forces of the MAO, MAO+GO and MAO+GO+SDBS three coatings were measured by a scratch tester. The mechanical property of the three coatings was analyzed using the nano-indentation technique. The corrosion resistance of the coatings was tested by the electrochemical system in 3.5% NaCl solution. The photocatalytic activity of the prepared samples was evaluated by determining the degradation of methylene blue(MB) solution. The results showed that compared to the MAO coating, the morphologies and phase compositions of MAO+GO and MAO+GO+SDBS composite coatings were significantly different. These two composite coatings all had superior photocatalytic activity. Especially, the MAO+GO composite coating still had enhanced binding force and excellent corrosion resistance. Furthermore, the relationship between the microstructure and the properties of these three MAO coatings was analyzed.     

氩弧熔覆镍基自熔合金的工艺研究

采用氩弧熔覆工艺在Q235钢基体上获得了F102Fe镍基合金熔覆层.测试了涂层的硬度和耐腐蚀性，借助光学金相显微镜、扫描电子显微镜观察其显微组织，进而对熔覆工艺、合金组织及熔覆层性能之间的关系进行详细阐述.研究结果表明，采用氩弧熔覆工艺可以在Q235钢基表面上获得与基体结合良好、组织细密、具有较高硬度和耐蚀性的F102Fe合金熔覆层.在相同的情况下，增加电流强度或减少熔覆层的厚度，组织由共晶向亚共晶转变；随熔覆层的硬度、耐蚀性降低，塑性有所改善.     

超临界碳化对水泥基材料性能和孔径结构的影响

为了考察超临界碳化技术在水泥基材料改性方面的应用,研究超临界碳化对水泥基材料微观和宏观性能的影响,基于此设计了超临界二氧化碳碳化试验研究水泥砂浆、水泥净浆和混凝土试件的碳化深度、强度、孔径分布以及二氧化碳吸收量的变化。试验分析表明,超临界碳化可以快速实现水泥基材料的碳化,大幅提高试件强度,改善材料的孔径分布,使材料的中细径孔大幅降低,提高材料的抗渗透能力,为改善重金属等危害废物的水泥基固化效果提供了依据。同时超临界碳化可以将大量二氧化碳转化在碳酸钙中沉淀吸收,具有重要的环境保护意义。     

Influence of Different Chelating Agents on Corrosion Performance of Microstructured Hydroxyapatite Coatings on AZ91D Magnesium Alloy

To improve the bioactivity and corrosion resistance of AZ91 D magnesium alloy,hydroxyapatite(HAp) coatings with novel microstructured morphologies were prepared successfully on AZ91 D substrates via a facile hydrothermal method.Different chelating agents including polyaspartic acid(PASP) and ethylenediaminetetraacetic acid(EDTA) were introduced to investigate their effects on the morphology and corrosion resistance of the coated magnesium alloys.The results revealed that the coating prepared with PASP was composed of many uniform urchin-like microspheres,while the coating prepared with EDTA consisted of many flower-like particles.Moreover,the crystallinity of the coating prepared with EDTA was much higher than that of the coating prepared with PASP.Electrochemical tests revealed that the corrosion resistance of the substrate was significantly improved after being coated with each coating.Immersion test of the coated samples in simulated body fluid(SBF) demonstrated that the coatings could be biodegraded gradually and induce the formation of calcium phosphate particles.     

Long-term Durability of Cement-based Materials with Very Low w/b

To investigate the durability, especially the long-term stability of cement-based materials with very low w/b, the air permeability test, carbonation test, capillary absorption rate test and dilation Dotential test were adopted under long-term heat treatment condition. Microstructure of these materials is also analyzed by scannmg electronic microscopy (SEM) and mercury intrusion porosimeter (MIP) in order to further unveil its mechanism and interrelation between microstructure and its properties. The results indicate that in the area investigated, cement-based material with w/b 0.17, like RPC, possesses low porosity and excellent durability. Moreover, its porosity will further decrease under long-term heat treatment compared with normal heat treatment. Its long-term durability is much superior to that of other cement-based materials with w/b 0.25 or 0.35 as high strength concrete (HSC).     

Ce改性AZ91的微弧氧化膜制备及其耐蚀性能

利用交流恒压微弧氧化技术, 通过Ce改性镁合金基体制备高耐蚀微弧氧化膜. 在100、120和 140 V的外加电压下, 对3种试样: AZ91, 质量分数w(Ce) 分别为0.92%和1.80%改性的AZ91微弧氧化过程、微观结构和组成及氧化膜的耐蚀性能进行研究. 应用电子扫描显微镜(SEM), 电子能谱（EDS）和X射线衍射（XRD）等表征氧化膜的微观结构和化学组成. 利用稳态极化曲线和电化学阻抗谱（EIS）测试了氧化膜在质量分数w(NaCl)为3.5%的溶液中的腐蚀过程. 实验结果表明氧化膜成膜过程可以分为3个阶段; 氧化膜主要由MgO组成, 镁合金中的稀土元素Ce促进成膜过程, 增加膜层的致密性; 稀土改性后镁合金氧化膜的耐蚀性比镁合金基体提高4个数量级, 腐蚀电流密度低至10^-8 A/cm2．     

STUDY ON CORROSION RESISTANCE OF REBAR IN HYBRID GRINDING FLY ASH-LIME SILICATE CONCRETE

The corrosion resistance of rebar in fly ash-Lime silicate concrete as well as its marco properties and pore distribution is investigated. The results show that the fly ash is activated, the compressrve strength of the silicate concrete is strengthened and its pore structure is modified after fly ash and lime being hybrid ground. Also the corrosion resistance of rebar in the silicate concrete is improved.     

VMS有机-无机杂化膜的制备及其防腐性能研究

以乙烯基三甲氧基硅烷（VMS）为前驱体,采用浸涂法在LY12铝合金表面制备了有机一无机杂化防腐保护膜．分别考察了涂膜次数、固化剂用量和溶剂用量对膜层防腐性能的影响,成膜的最佳工艺条件为：固化剂过氧化苯甲酰（BPO）的加入量为凝胶量的2％（质量分数）;凝胶质量与溶剂质量的比为0．17;涂膜四次．利用动电位极化曲线、盐雾实验和盐水浸泡实验评价了膜层的耐腐蚀性能．结果表明,乙烯基三甲氧基硅烷（VMS）膜层可使腐蚀电流减小到原来的1／300左右,同时也使得试片耐长久腐蚀的能力显著增强．     

纳米Cr颗粒对Ni-Mo复合镀层性能的影响

为了研究纳米Cr颗粒对Ni-Mo复合镀层性能的影响,采用脉冲电沉积方法制备具有不同Cr含量的Ni-Mo复合镀层.利用扫描电子显微镜和X射线衍射仪分别观察和分析复合镀层的组织形貌及结构.采用电化学测试和X射线光电子能谱研究复合镀层的析氢性能和耐蚀性能.结果表明:随着镀液中纳米Cr颗粒含量的增加,镀层晶粒得到细化,析氢过电位增大,复合镀层析氢性能得到提高;当镀液中纳米Cr颗粒含量为20 g/L时,复合镀层表面钝化膜中MoO₃含量较高,且可与Cr产生协同效应,因而复合镀层具有较好的耐蚀性能;但随着镀液中纳米Cr颗粒含量的进一步增加,复合镀层中沉积的Cr元素含量降低,复合镀层的析氢性能和耐蚀性能均降低.因此,当镀液中纳米Cr颗粒含量为20 g/L时,复合镀层具有较好的析氢性能和耐蚀性能.     

PCVD-TiC膜的工艺及其应用研究

通过正交试验对ＰＣＶＤ－ＴｉＣ膜的镀膜工艺参数进行了优化，得到了制备高硬度、高结合牢度和高沉积速率ＴｉＣ膜的工艺参数。试验表明，在用ＰＣＶＤ法沉积ＴｉＣ膜的过程中，ＴｉＣｌ４和ＣＨ４的流量是重要的控制参数。过多的ＴｉＣｌ４和ＣＨ４都会给ＴｉＣ膜带来不利的影响。氩气虽然可以提高ＴｉＣ膜的沉积速率，但同时也降低了膜与基之间的结合牢度。在冷挤压模具上应用的结果表明，镀有优化后的ＰＣＶＤ－ＴｉＣ膜的模具比镀ＴｉＮ膜的模具可提高寿命２～４倍。与不镀膜的模具相比，可提高寿命１０倍以上。     

Electrochemical corrosion behavior of arc sprayed Zn and Zn15Al coatings in simulated salina soil and neutral meadow soil solutions

Arc sprayed Zn and Zn15Al coatings were chosen to protect the metal ends of prestressed high-strength concrete (PHC) pipe piles against corrosion of salina soil in northern china and neutral meadow soil in northeast China. The corrosion behavior of the coated Q235 steel samples in two simulated soil solutions were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The experimental results show that the corrosion of the matrix Q235 steel in both simulated solutions is remarkably inhibited by Zn and Zn15Al coatings. The corrosion products on Zn and Zn15Al are thick, compact, firm and protective. The corrosion current density icorr of both Zn and Zn15Al-coated samples is decreased evidently with corrosion time, and the charge transfer resistance Rct is increased greatly. The corrosion resistance indexes of Zn and Zn15Al in simulated neutral meadow soil solution are more outstanding than those in salina soil. The corrosion resistance of Zn15Al in salina soil is slightly superior to that of Zn. When the sprayed coatings are sealed with epoxy resin, the corrosion resistance of the coatings is further enhanced markedly.     

多弧离子镀TiN涂层工艺及耐蚀性研究

为提高4Cr13马氏体不锈钢的耐蚀性,对其进行多弧离子镀处理,获得TiN涂层,并用X射线衍射仪、显微硬度计、扫描电子显微镜、电化学测量仪对涂层进行物相分析、表面形貌观察、硬度检测以及电化学腐蚀性能测试.结果表明:随着电流的增大,表面的液滴数目和尺寸增大,涂层厚度增加,薄膜硬度也增大;相结构主要为TiN,有明显的择优取向,且随着弧电流的增强,衍射峰强度略有增加.TiN试样在3.5％的NaCl溶液中耐蚀性与基体相当,在1 mol/L的H2SO4溶液中的耐蚀性比基体提高了800倍.     

Effect of calcium leaching on the properties of cement-based composites

Leaching is one of the major factors that alter the mechanical properties of cement-based composites. This study is aimed to investigate the effect of leaching on the properties of cement-based composites. Specimens with two water/cementitious ratios and two mineral admixtures were tested. An electrical potential was applied to accelerate the leaching process. Compressive strength test, scanning electronic microscopy, thermogravimetric analysis and X-ray diffraction analysis were conducted. Test results demonstrated that the calcium leaching reduced compressive strengths of concrete specimens, and such effect was prominent on the specimens without mineral admixtures. The leaching resistance increased with a decrease in water/cementitious ratio and an increase in amount of mineral admixtures. The mineral admixtures would reduce the amount of calcium hydroxide and refine the pore structure through pozzolanic reactions. A fair relationship was found between the calcium leaching and the compressive strength.     

SFRC subjected to domestic sewage and sustained load

The article aimed to study the durability of steel fiber reinforced concrete under the coupled sewage-loading according to compressive strength,flexural strength,compressive strength corrosion coefficient,flexural strength corrosion coefficient,compressive strength balance coefficient,flexural strength balance coefficient.Through the homemade load frame applied to design specimens,the pre-loading level are equivalent the damage intensity of 0%,10%,30% and 50% four different ways.The experimental results show that the performance of concrete down gradually and sustaining load aggravated the degree of domestic sewage attacking concrete after six month;under different stress states,the more loading levels,the more serious domestic sewage attacked the steel fiber reinforced concrete.It is proved that the concrete damage can be inhibited by adding the steel fiber,when steel fiber volume fraction is 1.0%,the corrosion resistance of concrete is best.     

Long-term durability of cement-based materials with very low <Emphasis Type="Italic">w/b</Emphasis>

To investigate the durability, especially the long-term stability of cement-based materials with very low w/b, the air permeability test, carbonation test, capillary absorption rate test and dilation potential test were adopted under long-term heat treatment condition. Microstructure of these materials is also analyzed by scanning electronic microscopy （SEM） and mercury intrusion porosimeter （MIP） in order to further unveil its mechanism and interrelation between microstructure and its properties. The results indicate that in the area investigated, cement-based material with w/b 0.17, like RPC, possesses low porosity and excellent durability. Moreover, its porosity will further decrease under long-term heat treatment compared with normal heat treatment. Its long-term durability is much superior to that of other cement-based materials with w/b 0.25 or 0.35 as high strength concrete（HSC）.