新型化学剂快速冷却热轧螺纹钢的防锈性能研究

研究20MnS i螺纹钢在经一种新型化学试剂FM处置后的防锈性能.结果表明,把这种化学试剂用于螺纹钢的轧后冷却过程,能在钢筋表面生成一层致密光亮的氧化皮,对钢筋起到很好的耐锈蚀保护作用.通过室外大气实验、干湿交替加速实验、盐雾加速实验及电化学实验,比较了采用化学试剂FM生成的氧化皮与水冷和空冷生成的氧化皮的耐锈蚀性能.结果表明,采用化学试剂FM生成的氧化皮的耐锈蚀性能优于水冷和空冷工艺,在保证螺纹钢力学性能的基础上大幅度的提高了其耐锈蚀性能,在螺纹钢生产过程中具有良好的应用前景.

海砂混凝土耐久性能研究

通过海砂混凝土不同条件下力学性能和耐久性的测试,对海砂高强混凝土中的钢筋锈蚀能力进行了研究。结果表明,海砂中氯离子含量在0.123%、在混凝土中使用量低于320kg/m3的条件下,对强度高于50MPa的混凝土立方体抗压强度、碳化性能、抗氯离子扩散性能影响不大;海砂混凝土的钢筋锈蚀失重率随着海砂掺量的增加和水胶比的增大而增加;阻锈剂的掺入和保护层厚度的增加,可使海砂混凝土的抗钢筋锈蚀能力有所改善,钢筋锈蚀程度有所下降。

秦始皇陵园陪葬坑严重锈蚀青铜水禽的保护修复

秦始皇陵园陪葬坑7号坑(K0007)共出土青铜水禽46件，其中20件天鹅、20件鸿雁、6件仙鹤，引起学术界的广泛关注。但是这批青铜水禽埋葬环境极为恶劣，出土时锈蚀相当严重，有的已完全锈蚀，有的已变形、断裂。

农用运输车车身焊接工艺优化

农用运输车制造主要分车身制造、发动机与底盘制造以及总装配3项内容。其中车身焊接是车身制造的重要工艺。传统的焊接方式为接触点焊，这种工艺存在3大问题，一是各钣金之间焊缝处的密封性和耐锈蚀性差,二是钣金与加强梁间的减振性差，三是对车身表面增添许多由焊接而造成的凹坑，影响外观质量。同时,车身焊接中存在2个问题，一是钣金因冲压成型变得薄弱，若受疲劳易产生裂纹而导致损坏，二是驾驶室内噪声问题。

Seismic strengthening of reinforced concrete columns damaged by rebar corrosion using combined CFRP and steel jacket

In order to study the effectiveness of combined carbon fiber-reinforced polymer （CFRP） sheets and steel jacket in strengthening the seismic performance of corrosion-damaged reinforced concrete （RC） columns, twelve reinforced concrete columns are tested under combined lateral cyclic displacement excursions and constant axial load. The variables studied in this program include effects of corrosion degree of the rebars, level of axial load, the amount of CFRP sheets and steel jacket. The results indicate that the combined CFRP and steel jacket retrofitting technique is effective in improving load-carrying, ductility and energy absorption capacity of the columns. Compared with the corrosion-damaged RC column, the lateral load and the ductility factor of many strengthened columns increase more than 90% and 100%, respectively. The formulae for the calculation of the yielding load, the maximum lateral load and the displacement ductility factor of the strengthened columns under combined constant axial load and cyclically increasing lateral loading are developed. The test results are also compared with the results obtained from the proposed formulae. A good agreement between calculated values and experimental results is observed.

滚轧直螺纹机械连接成套技术优缺点的理论分析

本文介绍了滚轧直螺纹连接技术的优势,并重点论述了其技术缺陷,包括螺牙磨损后力学性能下降;粘结强度降低;易锈蚀;易碳化和防火性能较差等。目的是促进我国等强度连接件技术的不断发展和完善。

Corrosion properties of stainless steel 316L/Ni-Cu-P coatings in warm acidic solution

In order to improve corrosion resistance of stainless steel 316L in warm acidic solution, Ni？Cu？P coatings with high copper and phosphorus contents were deposited onto stainless steel 316L substrates via electroless plating. The structure of the film and its resistance to corrosion in a warm acidic environment were investigated using scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, X-ray diffraction spectrometry （XRD）, polarization curves, electrochemical impedance spectroscopy （EIS）, and dipping corrosion tests, respectively. The results demonstrate that Ni？Cu？P coatings consist of two types of nodules, which are 19.98% Cu and 39.17% Cu （mass fraction） respectively. The corrosion resistance of the 316L substrate when subjected to a warm acidic solution is significantly improved by the addition of the new type of the Ni？Cu？P coating. The as-plated coatings demonstrate better corrosion resistance than annealed coatings. As-plated coatings and those annealed at 673 K are found to corrode selectively, while pitting is observed to be the main corrosion mechanism of coatings annealed at 773 and 873 K.

Reliability analysis for anchorage of reinforced concrete beams with longitudinal cracks due to corrosion at anchorage zone

An anchorage reliability analysis approach for simply supported reinforced concrete beams under corrosion attack in the anchorage zone is developed.The first-order second-moment method is employed to analyze the effects of various factors on the anchorage reliability.These factors include both the length and width of cover cracking due to reinforcement corrosion,the cover thickness,the anchorage length,and the stirrup ratio.The results show that the effect of corrosion-induced crack length on the reliability index for anchorage,β0,is negligible when the crack on the concrete surface is just appearing,but with the crack widening,the β0 value is reduced significantly;the considerable changes in β0 result from a variation in cover depth and anchorage length;the effect of changes in the diameter or space of stirrups on the anchorage resistance is very limited,and the variation in β0 is also very low.

PGP系列装配式镀锌钢管结构塑料大棚通过科研新产品鉴定

由中国科学院石家庄农业现代化研究所设计、河北省石家庄建筑机械厂协作试制的PGP系列装配式镀锌钢管结构塑料大棚,于1983年8月,通过河北省科委组织的科研新产品鉴定,认为是一种结合国情、借鉴国外技术研制成功的新型农业生物环境工程设施,具有结构强度高、牦用材料少、抗锈蚀性能好,便于安装、拆卸和进行环境管理等优点,达到了国内先进水平,

Microstructure and properties of laser cladding of 316L stainless steel on hydraulic support tube

In consideration of the special environmental conditions of coal equipment in mining, the seamless steel tube of hy-draulic prop made of 20^# carbon steel was taken as the substrate, and 316L stainless steel powder was used to clad the sub-strate by a fiber-coupled semiconductor laser. The microstructure of the cladding layer was determined by metalloscope. The hardness, wear resistance and corrosion resistance of the cladding layer were measured. The results show that metallurgy bind-ing interface between the cladding layer and the substrate is obtained without defects such as cracks and pores. The hardness of the cladding layer is much higher than that of the matrix, and the wear resistance and corrosion resistance are simultaneously better. According to the analysis, it is summarized that the improvement in performance of the cladding layer is closely related to the change of microstructure and the thermal effect in the cladding process. The maximum hardness occurs in the equiaxed zone, and with the grain coarsening, the hardness reduces simultaneously. In addition, the precipitated phase, hard particles and trace elements also have a great influence on the properties of the cladding layer, and they will prevent the surface from ab-rasion and reduce the plastic deformation of the matrix. It is verified that the 316L stainless steel is suitable for the 20^# steel in laser cladding repairing process. Since this study focused on coal machine equipment parts, it has certain practical significance for the repair of hydraulic equipment.

Influence of steel corrosion to flexural behavior of coral aggregate concrete beam

To study the flexural behavior and calculation model,8 coral aggregate concrete(CAC)beams with different types of steel were designed.The flexural behavior of CAC beam was tested.The failure mode,bearing capacity,the maximum crack width(ws)and average crack spacing(lm)were studied.A calculation model for the bearing capacity of CAC beam was proposed.The results indicated that with the steel strength increased,the cracking moment(Mcr)and ultimate moment(Mu)of CAC beam increased,and the development of the ws gradually slowed,which effectively inhibited the formation of cracks and improved the flexural behavior of CAC beam.For CAC structures in the ocean engineering,it is recommended to use organic new coated steel to extend its effective service life.In addition,considering the influence of steel corrosion,a calculation model for the Mcr,Mu,lm and ws of CAC beam was established.

Effect of Strain and Chloride Concentration on Pitting Susceptibility for Type 304 Austenitic Stainless Steel

The effects of strain and chloride concentration on pitting susceptibility for type 304 stainless steel were studied in situ using the electrochemical technology under constant strain. The impact factor fc was brought forward to value the effect of strain on pitting. The pitting behaviors of type 304 stainless steel in various chloride concentrations under the strain levels 0%, 10%, and 30% were investigated. Potentiostatic polarization technology was used to study how the chloride concentration affected corrosion current density. The results indicated that fc increased substantially and pitting potential varied remarkably when chloride concentration was over 90 mg.L . Under the three levels of strain mentioned above, when chloride concentration was below 463 mg.L^-1,121 mg.L^-1, and 98 mg.L^-1 respectively, the pitting potential shifted towards positivity and, the passive film became more stable. When the strain was below 10%, the pitting susceptibility of type 304 stainless steel varied greatly as strain increased, whereas the susceptibility only changed a little when the strain was over 10%.

Electrochemical characteristics of electroplating and impregnation Ni-P/SiC/PTFE composite coating on 316L stainless steel

Ni-P/SiC/PTFE coating was obtained on the surface of 316L stainless steel by electrodeposition of Ni-P/SiC coating and immersion of PTFE(polytetrafluoroethylene).The surface morphology and composition were analyzed by scanning electron microscope and energy dispersive spectrometer.The corrosion resistance of the coating in 0.5 mol/L H2SO4+2×10−6 HF solution was studied by electrochemical method.Surface contact angle was used to test the hydrophobic properties of the coating.The results indicated that the Ni-P/SiC/PTFE coating prepared on the surface of stainless steel was uniform and compact,which significantly improved the self-corrosion potential of stainless steel.The self-corrosion current density decreased from 7.62 to 0.008μA/cm2.The durability performance of coating was tested under 0.6 V voltage and the stable corrosion current density value was 0.19μA/cm2,then wetting angle was tested after durability experiment and the value is 134.5°.

高耐久性混凝土在预应力桥梁中的应用研究

在保证混凝土强度和坍落度的情况下 ,按耐久性指标 ,即盐冻剥落量、DF值、Cl- 离子扩散深度和钢筋锈蚀率对 C5 0空心板梁混凝土进行材料配合比设计。同时 ,比较了按耐久性设计优化混凝土与按传统设计混凝土两者间的性能优劣 。

Bond Property Test of Reinforced Concrete with All Soaking and Impressed Current Method Corrosion

In order to research the bond properties between corroded reinforcement bars and concrete,reinforcement bars with different diameters and different types and concrete with different strength levels were treated specially with all soaking and impressed current method,and the bond properties were measured with the pull-out test.The comparative analysis of the bond properties of corroded reinforcement bars was carried out.The results showed that the types of reinforcement bars and concrete had great influence on the bond strength.The corrosion and volume expansion of reinforcement bars made concrete in tensile condition,which tended to produce cracks in parallel reinforced direction.The typical bond failure of plain reinforcement bars was pull-out,while the typical bond failure of ribbed reinforcement bars was split.The bond strength between corroded reinforcement bars and concrete increased with the increase of concrete strength.The bond strength of plain and ribbed reinforcement bars showed a decreasing trend after the first increase with the increase of the extent of corrosion.Through the test,the coefficients of the bond strength of plain and ribbed reinforcement bars were given,respectively.

Discharge Characteristics of Micro-Needle Array Diamond Structure

CVD polycrystalline diamond surfaces were etched using reactive ion etching system with either a conventional stainless steel electrode or MgO sintered ceramic containing electrode. The micro-needle array of high aspect on diamond substrate surfaces obtained with MgO electrode was fabricated by using back-sputtering from MgO electrode. The RMS roughness of diamond substrate surfaces obtained with MgO electrode is higher than those obtained with stainless steel electrode. The secondary electron emission coefficient in Ne gas of the diamond obtained with MgO electrode was twice that obtained with the stainless steel electrode.

乘用车制动盘锈粘结问题分析

针对乘用车常见的制动盘与摩擦片之间锈粘结问题,对某款车型的制动盘与摩擦片锈粘结问题进行分析,发现锈粘结问题的产生机理为制动盘和摩擦片中铁元素发生电化学反应,结合原电池反应发生的4个条件,从理论上提出相应的解决措施,切断原电池反应过程,避免渗透性锈蚀产生。对发生锈粘结故障的车辆,通过增加制动盘防锈能力、降低电化学反应金属元素间电势差、增加摩擦片PH值以及降低孔隙率等优化措施弱化制动盘与摩擦片间的电化学反应,并制作改善性样件进行盘片脱开力台架试验和整车验证,结果表明通过切断原电池反应条件可以有效改善锈粘结问题,为同类零部件设计提供经验参考。

铜供水管道优点多

目前在我国广大城镇用于供水的镀锌铁管,已经在许多发达国家和地区被明令禁止使用,我国香港特别政行区自1996年1月1日起也已禁止使用。现在,我国内地有些城市和地区,正在考虑禁止使用的日期,这是因为镀锌铁管很容易锈蚀,污染供水水质,影响居民身体健康。 与镀锌铁水管系统相比。

Durability of calcium sulfoaluminate cement concrete

Calcium sulfoaluminate cement(CSAC),first developed in China in the 1970 s,has received significant attention because of its expansive(or shrinkage-compensating)and rapid-hardening characteristics,low energy-intensity,and low carbon emissions.The production and hydration of CSAC(containing ye’elimite,belite,calcium sulfate,and minors)have been extensively studied,but aspects of its durability are not well understood.Due to its composition and intrinsic characteristics,CSAC concrete is expected to have better performance than Portland cement(PC)concrete in several aspects,including shrinkage and cracking due to restrained shrinkage,freeze-thaw damage,alkali-silica reaction,and sulfate attack.However,there is a lack of consensus among researchers regarding transport properties,resistance to carbonation,and steel corrosion protectiveness of CSAC concrete,all of which are expected to be tied to the chemical composition of CSAC and attributes of the service environments.For example,CASC concrete has poorer resistance to carbonation and chloride penetration compared with its PC counterpart,yet some studies have suggested that it protects steel rebar well from corrosion when exposed to a marine tidal zone,because of a strong self-desiccation effect.This paper presents a succinct review of studies of the durability of CSAC concrete.We suggest that more such studies should be conducted to examine the long-term performance of the material in different service environments.Special emphasis should be given to carbonation and steel rebar corrosion,so as to reveal the underlying deterioration mechanisms and establish means to improve the performance of CSAC concrete against such degradation processes.