Fundamentals of fast reduction of ultrafine iron ore at low temperature

Fundamentals on the fast reduction of ultrafine iron ore at low temperature, including characterization of ultrafine ore, deoxidation thermodynamics of stored-energy ultra.fine ore, kinetics of iron ore deoxidation, and deoxidation mechanism, etc., and a new ironmaking process are presented in this article. Ultrafine ore concentrate with a high amount of stored energy can be produced by mechanical milling, and can be deoxidated fast below 700℃ by either the coal-based or gas-based process. This novel process has some advantages over others： high productivity, low energy consumntion, and environmental friendliness.

An ultra-fast charging strategy for lithium-ion battery at low temperature without lithium plating

Conventional charging methods for lithium-ion battery(LIB)are challenged with vital problems at low temperatures:risk of lithium(Li)plating and low charging speed.This study proposes a fast-charging strategy without Li plating to achieve high-rate charging at low temperatures with bidirectional chargers.The strategy combines the pulsed-heating method and the optimal charging method via precise control of the battery states.A thermo-electric coupled model is developed based on the pseudo-twodimensional(P2D)electrochemical model to derive charging performances.Two current maps of pulsed heating and charging are generated to realize real-time control.Therefore,our proposed strategy achieves a 3 C equivalent rate at 0℃ and 1.5 C at-10℃ without Li plating,which is 10–30 times faster than the traditional methods.The entropy method is employed to balance the charging speed and the energy efficiency,and the charging performance is further enhanced.For practical application,the power limitation of the charger is considered,and a 2.4 C equivalent rate is achieved at 0℃ with a 250 kW maximum power output.This novel strategy significantly expands LIB usage boundary,and increases charging speed and battery safety.

Effect of Surface Nanocrystallization Induced by Fast Multiple Rotation Rolling on Cr-Rare Earth-Boronizing for Steel 45 under Low-Temperature

In this paper, fast multiple rotation rolling （FMRR） is applied to fabricate a nanostructured layer on the surface of steel 45. The FMRR samples are then Cr-Rare earth-boronized under low-temperature. The boride layer is characterized by using Scanning electron microscopy （SEM） and X-ray diffraction （XRD）. Experimental results indicate that the thickness of the boride layer is greatly increased by surface nanocrystallization. The boride layer with relatively continuous structure instead of the zigzag teeth structure is obtained, and the penetrating rate is enhanced by 2. 5-3.7 times when the FMRR samples are Cr-Rare earth- boronized at the temperature of 570 %, 600℃ and 650℃ for 6 h. The boride layer fabricated on the FMRR sample consists of single phase Fe2B. Severe plastic deformation with the grain size of approximately 100 nm in the top surface layer of steel 45 is observed, and the thickness of the plastic deformation layer is about 30 6xm. The microstructure in the top surface layer is characterized by Transmission electron microscopy （TEM）. Grain boundaries are largely increased with high stacking fault energy after FMRR, leading to a significant enhancement of RE boron-chromizing speed.

Overwhelming low ammonia escape and low temperature denitration efficiency via MnOx-decorated two-dimensional MgAl layered double oxides

Low temperature catalysts are attracting increasing attention in the selective catalytic reduction(SCR)of NO with NH3.Mn Ox-decorated Mg Al layered double oxide(Mn/Mg Al-LDO)was synthesized via a facile fast pour assisted co-precipitation(FP-CP)process.Compared to the Mn/Mg Al-LDO obtained via slow drop assisted coprecipitation(SD-CP)method,the Mn/Mg Al-LDO(FP-CP)has excellent activity.The Mn/Mg Al-LDO(FP-CP)catalyst was shown to possess a high NO conversion rate of 76%-100%from 25 to 150℃,which is much better than the control Mn/Mg Al-LDO(SD-CP)(29.4%-75.8%).In addition,the Mn/Mg Al-LDO(FP-CP)offered an enhanced NO conversion rate of 97%and a N2selectivity of 97.3%at 100℃;the NO conversion rate was 100%and the N2selectivity was 90%at 150℃with a GHSV of 60,000 h^-1.The Mn/Mg Al-LDO(FP-CP)catalyst exhibited a smaller fragment nano-sheet structure(sheet thickness of 7.23 nm).An apparent lattice disorder was observed in the HRTEM image confirming the presence of many defects.The H2-TPR curves show that the Mn/Mg Al-LDO(FP-CP)catalyst has abundant reducing substances.Furthermore,the enhanced surface acidity makes the NH3concentration of the Mn/Mg Al-LDO(FP-CP)catalyst lower than 100 ml·m^-3after the reaction from 25 to 400℃.This can effectively reduce the ammonia escape rate in the SCR reaction.Thus,the Mn/Mg Al-LDO(FP-CP)catalyst has potential applications in stationary industrial installations for environmentally friendly ultra-low temperature SCR.

Distinct effect of preparation methods on reaction efficiency of Mn-Ce/Al_(2)O_(3) catalysts in low-temperature NH_(3)-SCR

In this study,a series of Mn-Ce/Al_(2)O_(3) catalysts was prepared by different methods of depositionprecipitation(MnCeAl-DP),impregnation(MnCeAl-IM) and citric acid(MnCeAl-CA),and the distinct effect of preparation methods on NO_x removal performance at low temperature was explored.Results show that MnCeAl-DP exhibits not only the best activity but also the highest resistance against SO_(2)/H_(2)O.With the assistance of comprehensive characterizations from scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),H_(2)-temperature programmed reduction(H_(2)-TPR),NH_(3)-te mperature programmed deso rption(NH_(3)-TPD),and X-ray photoelectron spectroscopy(XPS),it is revealed that the MnCeAl-DP sample owns admired features of large surface area and pore volume,enriched Mn^(4+) and chemisorbed oxygen species originating from enhanced interaction between MnO_x and CeO_(2),as well as improved adsorption capacity to NH_3 and NO.All these factors contribute to activity enhancement.Further in-situ DRIFTS studies reveal that the improvement of NH_(3)-SCR performance over MnCeAI-DP is related to the formation of abundant nitrate species,which is beneficial to the "NH_(4)NO_(3)" reaction pathway and thus enhances low-temperature activity.

Microstructure and Mechanical Properties of Nb-B bearing Low Carbon Steel Plate: Ultrafast Cooling versus Accelerated Cooling

The microstructure and mechanical properties of low carbon bainite high strength steel plate were studied via different cooling paths at the pilot scale. There was a significant increase in mechanical properties, and notably, the yield strength, tensile strength, and toughness at-40 ℃ for the tested steel processed by ultra-fast cooling were 126 MPa, 98 MPa and 69 J, respectively, in relation to steel processed by accelerated cooling. The ultra-fast cooling rate not only refined the microstructure, precipitates, and martensiteaustenite（M/A） islands, but also contributed to the refinement of microstructure in thick plates. The large size M/A constituents formed at lower cooling rate experienced stress concentration and were potential sites for crack initiation, which led to deterioration of low-temperature impact toughness. In contrast, the acicular ferrite and lath bainite with high fraction of high-angle grain boundaries were formed in steel processed by ultra-fast cooling, which retarded cleavage crack propagation.

新型皂洗体系在活性染料低温皂洗中的应用

将剥离型低泡沫净洗剂FMES与螯合分散剂EDDHA-Na、过氧化氢及其催化剂马来酸五乙酰葡萄糖(PGM)进行复配,得到一种新型50℃低温皂洗体系。该体系利用催化剂PGM在低温条件下与过氧化氢快速分解出氧化能力更强的过氧酸,充分破坏残液中染料的发色基团,降低残液的色度,以实现低温皂洗的防沾色。测试皂洗后织物的耐皂洗色牢度、染色残液吸光度以及布面色变等指标,优化了新型低温皂洗体系的组成,即FMES 1.0 g/L、PGM 0.9 g/L、H_(2)O_(2) 3 g/L、EDDHA-Na 1.5 g/L。该四元皂洗体系低温皂洗力强,防沾色效果明显,染色残液色度低,可实现活性染料的低温、小浴比、短流程皂洗。

适用于曲面陶瓷岩板的坯体配方研究

本文通过引入一种改性粘土工艺制作的增韧剂,研究了一种K_(2)O-Na_(2)O-CaO-B_(2)O_(3)-MgO多元复合熔剂低温快烧型坯体配方,所制备的陶瓷岩板经热弯处理,在热弯温度低至900℃,保温时间低至1h的工艺条件下,能够较好实现平面岩板的热弯成型。

大型风电叶片用低放热灌注环氧树脂的研制

随着风电叶片往大型化的方向发展以及风电叶片生产提速的需求,传统的灌注环氧树脂由于放热温度过高,往往会引起叶片的局部质量缺陷。针对这一问题,开发了一种适用于大型风电叶片的低放热快速固化环氧树脂体系。这里将开发的低放热环氧树脂体系的固化放热情况,固化速度和标准灌注环氧树脂进行了比较,结果表明,低放热环氧树脂反应焓和放热温度都明显低于标准环氧树脂。反应焓降低了129 J/g,放热温度显著降低。固化时间有所缩短,文章还对该树脂的其他工艺性能、浇铸体性能和复合材料性能进行了全面表征,结果是树脂的力学性能有小幅提高,综合性能满足大型风电叶片的要求。该树脂体系已成功应用于100 m级大型风电叶片上。

Controlled Rolling and Cooling Process for Low Carbon Cold Forging Steel

Effect of controlled rolling and cooling process on the mechanical properties of low carbon cold forging steel was investigated for different processing parameters of a laboratory hot rolling mill. The results show that the specimens with fast cooling after hot rolling exhibit very good mechanical properties, and the improvement of the mechanical properties can be attributed mainly to the ferrite-grain refinement. The mechanical properties increase with decreasing final cooling temperature within the range from 670 ℃ to 570 ℃ due to the finer interlamellar spacing of pearlite colony. The specimen with fast cooling after low temperature rolling shows the highest values of the mechanical properties. The effect of the ferrite grain size on the mechanical properties was greater than that of pearlite morphology in the present study. The mechanical properties of specimens by controlled rolling and cooling process without thermal treatment were greatly superior to that of the same specimens by the conventional rolling, and their tensile strength reached 490 MPa grade even in the case of low temperature rolling without controlled rolling. It might be expected to realize the substitution medium-carbon by low-carbon for 490 MPa grade cold forging steel with controlled rolling and cooling process.

纳米化诱导TC4合金表面低温等离子渗氮研究

研究Ti-6Al-4V(TC4)合金的表层力学性能,有助于延长TC4合金的使用寿命,拓宽其表面改性的应用。文章利用快速多重旋转碾压(Fast Multiple Rotation Rolling,FMRR)技术对TC4合金进行表面纳米化预处理,再对其进行低温等离子渗氮。结果表明:经FMRR及低温渗氮复合处理后,TC4合金表层获得1~3μm厚且连续、致密的氮化物层;经FMRR处理60 min,渗氮表面显微硬度较基体硬度提高了81.3%,而渗氮层摩擦系数降低;在作用14 N的外加载荷时,磨损量较原始试样减少了3.5 mg,磨损率为5.71×10^(-6)mg/mm,其值降低了44.8%;渗氮试样在低载荷摩擦磨损后,表面无明显犁沟及黏着现象,在高载荷下磨损机制以磨粒磨损及黏着磨损为主。

双组分丙烯酸聚氨酯涂料干燥速度的影响因素剖析

分析了丙烯酸聚氨酯涂层固化过程中摆杆硬度的变化规律,认为涂层的干燥速度主要由涂层的初始硬度和硬度增长速率决定。涂层的初始硬度可用Fox方程估算,取决于树脂、固化剂的玻璃化转变温度和用量,硬度增长速率可用Arrhenius方程描述,与固化反应的活化能、碰撞因子和反应温度有关。利用这一原理系统地分析了影响涂层干燥速度的因素,为低温快固化聚氨酯涂料的研究指明了方向。

涤锦经弹麂皮绒面料的加工工艺

本文旨在开发一种涤锦交织面料的加工工艺,通过工艺设计、试样制作、检测分析、效果对比等方法,发现涤锦织物低温上色工艺一方面能提高织物的干湿擦色牢度,另一方面工艺流程短,上色温度比涤纶织物低30℃左右,大幅度降低能耗,节约生产成本;所加工的涤锦经弹麂皮绒面料触感柔软滑爽、吸湿透气,市场前景广阔。

快速固化水性环氧厚涂型底漆的制备及性能研究

采用基于腰果壳油改性的水性环氧固化剂搭配低相对分子质量液体环氧树脂以及助剂,制备了快速固化、底中合一的水性环氧地坪涂料,尤其在低温下,快速固化的特点同样能够继续保持。同时,地坪涂料具备良好的涂膜外观、粘接强度以及耐化学性能。缩短了施工周期,使得水性地坪涂料的快速施工成为可能。

烟煤固体热载体低温快速热解实验研究

以连续式热解装置为实验平台,藁城和府谷煤为原料,石英砂为热载体,考察了460～520℃范围内热解所得气、液产物收率、组成和性质的变化规律.结果表明,在考察的温度范围内,提高热解温度,热解气、液产物收率增加,液体产物收率最高可达12%左右.热解温度对热解产物中不凝气组成影响显著,热解煤气热值高达25MJ/Nm3以上.焦油组分中酚衍生物含量最高,稠环烃、芳香烃、链烃组分的含量也较高,酚含量随热解温度增高有所降低,而芳烃含量则显著提高.根据实验结果提出了酚-芳烃转化的可能路径.

低温下多级AO-MBR工艺处理市政污水中试研究

针对低温条件下常规水处理技术难以满足出水要求的问题,对多级AO-膜生物反应器(MAO-MBR)工艺处理市政污水的情况进行研究,考察在低温下(7~13℃)对有机物和氮磷的去除效果。结果表明,在DO的质量浓度2.0 mg/L、回流体积比150%、HRT为18 h、MLSS的质量浓度6 g/L条件下,NH_3-N负荷、TN负荷分别为15 g/(kg·m^3)、20 g/(kg·m^3),出水COD、NH_3-N、TN、TP的去除率可分别达到96%、98%、85%、97.5%,出水水质达到GB 18918-2002的一级A标准。

高强度厚规格海洋平台用钢研究进展及应用

随着石油工业的不断发展,海底油气开发已经逐渐从浅海大陆架延伸至深海域,在降低成本的基础上,保证厚规格钢板的高强度高韧性以及抗层状撕裂性能是未来海洋平台用钢的发展方向。本文介绍了国内外高强度海洋平台用钢的研究现状,分析了此类钢板生产亟需解决的关键技术难题,阐述了东北大学轧制技术及连轧自动化国家重点实验室(RAL)近年来在高强度厚规格海洋平台用钢研究领域的工作以及工程应用情况。

空气中纳秒脉冲均匀介质阻挡放电研究

大气压空气中均匀介质阻挡放电具有广泛的应用前景,实现均匀放电是介质阻挡放电应用关键之一,因而利用上升沿40ns,脉宽70ns的重复频率纳秒脉冲电源激励在大气压空气中产生介质阻挡放电,介绍了纳秒脉冲均匀介质阻挡放电的电特性和放电图像及放电发射光谱,获得了2ns曝光时间的高速摄影放电图像。发现空气中1mm气隙距离下可以实现均匀放电,气隙距离增加至4mm时放电转变为明显的丝状放电,通过观察发射光谱显示等离子体谱线主要是来自400nm以下的氮分子第二正系。结果证实了大气压空气中利用ns脉冲激励可以产生稳定介质阻挡放电,且能实现均匀放电,是典型非平衡态低温等离子体。

羊毛低温染色助剂应用性能及作用机制

研究了LDW-630羊毛低温染色助剂的应用性能,并对其作用机理进行了探讨。结果表明,应用低温染色助剂可以使羊毛织物在80～85℃下染得常规染色的表观色深度,染色牢度达到常规染色的牢度等级,染透性达到常规染色水平,染色后羊毛单纤维断裂强力和伸长比常规染色工艺有明显提高。促染作用机理研究结果表明,LDW-630羊毛低温染色助剂能促进染料的溶解和分散。红外光谱分析结果表明,LDW-630羊毛低温染色助剂能在染色过程中打开羊毛纤维中的二硫键生成巯基和硫氧化合物,巯基在羊毛纤维暴露于空气中时部分氧化回二硫键状态,保证羊毛强力,提升染色牢度。

Baylan NT低温染色工艺在毛纺工业上的应用

通过采用BaylanNT低温助剂的低温染色试验,与常规的沸点染色相比较,表明应用BaylanNT助剂低温染色试样的色牢度与常规染色色牢度同水平,低温染色尽染率高。国外的BaylanNT低温染色应用试验研究显示,BaylanNT低温染色助剂有优异的促染作用,能提高染色动力,显著地提高低温透染与匀染性。