磁性碳球的制备与表征

以葡萄糖、葡萄糖酸亚铁和十六烷基三甲基溴化铵(CTAB)为原料,采用水热法结合退火处理制得磁性碳球。重点考察了水热反应中反应物的浓度、反应温度和时间等参数对样品形貌和结构的影响。利用场发射扫描电子显微镜、X 射线衍射仪、X 射线光电子能谱、红外光谱仪、热重分析仪和振动磁强计等对所制备的磁性碳球进行表征。结果表明：当葡萄糖溶液浓度0.1 mol/L、葡萄糖酸亚铁质量浓度1.667 g/L、CTAB 质量浓度6.667 g/L、温度170℃、时间12 h 时,得到了粒径尺寸均一、表面光滑、形貌规整、分散性良好并且具有一定铁磁性的碳球,其平均粒径约为600 nm。此外,分析了磁性碳球的形成机理。     

球化退火后轴承套圈锻坯表层的显微组织

为满足加工工艺的要求，对轴承套圈锻坯进行了球化退火处理。对球化退火后轴承套圈锻坯表层的显微组织进行分析。结果表明：如果炉气碳势控制不当，在锻坯表面会形成脱碳层；随着炉气碳势逐渐降低，对应生成不同的球化组织，二者之间的对应关系符合扩散定律菲克方程的误差解；结合Fe-Cr-C三元相图，不同炉气碳势会导致碳含量不同；绘制了碳浓度曲线，表层组织的转变符合该曲线的变化规律。     

钢中渗碳体特性的理论计算与实验研究

采用第一性原理方法计算了钢中渗碳体的电子结构、力学与物理性能.确定了不同结构Fe3C、Fe2C及Fe5C2等铁碳化物之间的稳定性,从原子和电子层次揭示了添加合金元素与附加应力对渗碳体相稳定性的影响规律与机制.研究了珠光体渗碳体在大冷变形及退火过程中的演变规律,建立了共析珠光体钢在大冷变形过程中铁素体的碳过饱和度与冷轧压下率问的定量关系,阐明了添加元素Cr、Mn、Si对冷变形过程中渗碳体溶解行为的影响规律,给出了重度冷轧后珠光体钢的退火组织分为细晶区与粗晶区的有力判据,分析了粗晶区与细晶区中渗碳体颗粒随退火时间的变化规律,发现2个区域内珠光体渗碳体颗粒的粗化动力学均符合关系式d=ktn,但渗碳体颗粒的粗化机制不同,而且进一步研究了Cr、Mn、Si等元素对2个区域内渗碳体颗粒粗化机制的影响规律.此外还研究了中高碳钢在温变形与热变形条件下渗碳体的球化规律,提出了高碳珠光体钢在不变形、中碳钢在珠光体区大变形条件下渗碳体的快速球化工艺,为进一步深化与丰富钢铁材料的超细化理论及其工业化应用提供了理论与实验支持.     

电子线缆用Cu-0.5Ag合金微细线材软化温度的测定方法

目前国内外对铜合金微细线材软化温度的测定没有出台相应的标准。通过室温拉伸试验和硬度测试使用抗拉强度和硬度测定的电子线缆用Cu-0.5Ag合金微细线的软化温度并对试验结果进行了对比分析。结果表明:使用抗拉强度和硬度测定得到的Cu-0.5Ag合金微细线的软化温度相近;使用硬度测定Cu-0.5Ag合金微细线材软化温度有很多不确定性,载荷、线径尺寸和测试位置对软化温度的测定结果均有影响。使用抗拉强度测定电子线缆用铜合金微细线材的软化温度更简便和可靠。     

一种伸长率试验仪在线校准装置

电线电缆行业生产检测中有许多要使用到伸长率试验仪,伸长率试验仪是专为各种线材及金属材料作伸长特性测试的可靠设备,它能够精确测量铜线、铝线、铝镁合金丝、铁丝等金属丝之伸长率(延伸率)的特性.为了能够实现伸长率试验仪的现场校准,研制了一种伸长率试验仪在线校准装置,可以在线现场检测,无需使用卡尺、钢卷尺进行计算测量.实验证明...     

H68黄铜挠性波导管制造缺陷分析

挠性波导管在生产过程中经常出现波导管齿形不规则、缩齿困难以及齿根撕裂的问题.以H68黄铜挠性波导管为例,通过对影响其质量的壁厚、软化退火工艺、酸洗工艺、滚齿模结构和钎焊工艺等因素进行了分析,得知造成以上缺陷的主要原因是毛坯管壁厚超差、滚齿模结构引起滚压轮同齿条啮合过紧、间隙不均以及退火温度选择不当.最后通过对H68黄铜...     

纳米Al2O3粒子浓度对弥散强化铜合金退火行为的影响

通过力学性能、金相和TEM观察对低、中浓度Cu-Al2O3弥散强化铜合金的退火行为进行了研究.结果表明:低浓度弥散强化铜合金具有一定的抗高温软化性能,500℃退火后发生再结晶,900℃退火后已基本完全再结晶,屈强比约为56%.中浓度合金抗高温软化性能较好,900℃退火后,合金仍然以回复过程为主,金相尺度下不能看到再结晶晶粒,屈强比可达70%.弥散强化铜合金优越的抗高温软化性能归功于铜基体内均匀弥散分布的纳米Al2O3粒子.Al2O3粒子尺寸在10～20nm内时,粒子间距＞200nm时,阻碍晶界迁移能力较差,粒子间距＜90nm时,可显著阻碍晶界的迁移,合金抗高温软化性能优越.     

二高线水冷段气动薄膜阀连接方式优化设计

随着高速线材的规格和品种不断扩大,高速线材已经不仅用于生产建筑,而且已广泛用于制绳、制钉和其他深加工领域。轧后穿水冷却也称作在线热处理,是直接关系到最终产品力学性能及其均匀性的关键工艺,可以有效的减少和控制线材的表面缺陷。因此轧后控制冷却可以大幅度提高高速线材的产品质量,增加产品的附加值,同时实现生产节能,大大提高线材产品在同行业中的竞争力。     

单向纤维晶组织Cu-0.1 Fe合金线材的再结晶温度

利用连续定向凝固和冷加工相结合的方法制备了含0．1％Fe无氧铜单向纤维晶线材，研究了线材的再结晶温度，退火温度对抗拉强度的影响，结果表明：在退火温度不高于500℃，保温1小时的条件下，线材不发生再结晶，仍然保持原有纤维晶组织，当温度高于600℃时，线材内部发生了完全再结晶，原来的纤维晶变成球状晶，线材的抗拉强度显著下降。     

碳球修饰TiO_2阳极薄膜对染料敏化太阳能电池性能的影响

为了提高电池的光电转化性能,将不同量的碳球加到二氧化钛糊中,经550℃高温退火30min到50min后制备了高比表面积的纳米二氧化钛薄膜阳极,该二氧化钛薄膜阳极经XRD、BET、HR-TEM、XPS表征,并进行了电化学实验,结果证明被1.0%碳球修饰的薄膜阳极由于具有较高的比表面积而吸收了较多的染料并获得4.17%的光电转化效率。     

Annealing kinetics of cold-rolled plain carbon steels

Softening of rimmed steel during batch annealing is due to recrystallization, grain growth and carbide coarsening. The post-recrystallization softening process is used commercially to control product quality and its kinetics can be characterized by an apparent activation energy. This parameter is shown to increase with decreasing carbon content owing to the influence of carbide particle dissolution on the grain growth rate. The latter effect is suppressed by low manganese and high sulphur contents because of the formation of fine manganese sulphide precipitates. The apparent activation energy of softening can be applied to improve the economics of industrial batch annealing.     

Directly spheroidizing during hot deformation in GCr15 steels

The spheroidizing heat treatment is normally required prior to the cold forming in GCr15 steel in order to improve its machinability. In the conventional spheroidizing process, very long annealing time, generally more than 10 h, is needed to assure proper spheroidizing. It results in low productivity, high cost, and especially high energy consumption. Therefore, the possibility of directly spheroidizing during hot deformation in GCr15 steel is preliminarily explored. The effect of hot deformation parameters on the final microstructure and hardness is investigated systematically in order to develop a directly spheroidizing technology. Experimental results illustrate that low deformation temperature and slow cooling rate is the favorite in directly softening and/or spheroidizing during hot deformation, which allows the properties of asrolled GCr15 to be applicable for post-machining without requirement of prior annealing.     

Directly spheroidizing during hot deformation in GCr15 steels

The spheroidizing heat treatment is normally required prior to the cold forming in GCr15 steel in order to improve its machinability. In the conventional spheroidizing process, very long annealing time, generally more than 10 h, is needed to assure proper spheroidizing. It results in low productivity, high cost, and especially high energy consumption. Therefore, the possibility of directly spheroidizing during hot deformation in GCr15 steel is preliminarily explored. The effect of hot deformation parameters on the final microstructure and hardness is investigated systematically in order to develop a directly spheroidizing technology. Experimental results illustrate that low deformation temperature and slow cooling rate is the favorite in directly softening and/or spheroidizing during hot deformation, which allows the properties of as-rolled GCr15 to be applicable for post-machining without requirement of prior annealing.     

Ferrite recrystallisation and characteristics of non-recrystallised ferrite grains in Ti added low carbon steels

The progress of ferrite recrystallisation in low carbon steel was slower than in ultralow carbon steel. The hardness of the non-recrystallised ferrite grains gradually decreased with increasing annealing time in ultralow carbon steel, but gradually increased with increasing annealing time in low carbon steel. The amount of Ti containing precipitates increased slightly during annealing in ultralow carbon steel, but increased remarkably with increasing annealing time in low carbon steel. These results suggest that the softening of non-recrystallised ferrite grains during annealing in ultralow carbon steel may reflect the progress of recovery and the Ostwald ripening of Ti containing precipitates formed during annealing. In contrast, the hardening of non-recrystallised ferrite grains in low carbon steel may be due to the precipitation hardening of TiC formed during annealing.     

Cold-drawn pearlitic steel wires

Cold-drawn pearlitic steel wires have attracted considerable interest because of their excellent combination of strength and ductility. The physical interpretation of these properties has been a subject of repeated controversial discussions in the literature. Unquestioned is the fact that during the process of cold drawing, cementite is partially dissolved, while the ferrite is obviously enriched in carbon. The debate is related to the questions why cementite is decomposed and where the carbon is accommodated. It is the aim of this work to review the relevant literature and to conciliate the controversies. Special attention is paid to the microstructural evolution during progressive cold-drawing, which eventually attains nanometer-scale in two dimensions and is essential for the evolution of the mechanical as well as electrical properties. This is all the more important as recent developments in atom probe tomography allowed to study the chemical composition on the atomic scale. A further important aspect is the path of recovery and recrystallization, accompanied by softening, during post-draw annealing. A consolidated view indicates that carbon-defect interactions play a major role in all aspects of the wire properties.     

超细不锈钢丝光亮热处理工艺试验研究

对φ０．０２５ｍｍ的超细不锈钢丝的光亮热处理工艺进行了试验研究，提出了满足织网工艺要求的超细不锈钢丝力学性能指标和达到该指标的最佳光亮热处理工艺参数。     

设防爆层钢箱梁缩尺结构抗近场爆炸作用试验研究

为研究设防爆层钢箱梁抗近场爆炸作用效果,以53 g炸药当量、70 mm爆距为典型爆炸条件,开展了混凝土-单层/双层钢丝网板、5层/10层凯夫拉板及其组合为防爆层的钢箱梁缩尺结构近场爆炸试验研究。以塑性变形能为抗爆效果考查指标,8种试验工况结果表明:近场爆炸作用下无防护钢箱梁顶板会发生沿U型加劲肋的撕裂破坏及球冠状凹坑,且横隔板间距250 mm比间距150 mm的钢箱梁顶板破坏严重,变形能约高出60%;混凝土-双层钢丝网板较单层钢丝网板能降低钢箱梁顶板的变形能约2.2%;混凝土-双层钢丝网板与5层凯夫拉组合作为防爆层,顶板塑性变形能降低至无防护结构钢箱梁顶板的34.5%,混凝土-双层钢丝网板与10层凯夫拉组合作为防爆层,该数值约为32.7%。     

Non-monotonic radial distribution of tensile yielding strength in cold-drawn pearlitic wire

It is commonly accepted that the surface layer in the cold-drawn pearlitic steel wire has a higher strength than the centre. In the present work, via testing the cold-drawn wire after removing the surface layer by an electrochemical method, it is discovered that the tensile yielding strength distributes non-monotonically from the surface to the centre. A valley is observed at the sub-surface. It is found that the maximum accumulative strain during drawing occurs at the sub-surface which leads to more hardening. The presence of residual stress after drawing reduces the tensile yielding stress. With increasing thickness of the removed layer, the tensile yielding stress increases monotonically. Finally, the only reason for the non-monotonic distribution of the tensile yielding stress is the strain path which the material at the sub-surface experiences in drawing and subsequent tension. It actually belongs to a reverse and a cross loading, which result in softening.     

Torsional fatigue with axial constant stress of oligo‐crystalline 316L stainless steel thin wire

A series of symmetric torsional fatigue with axial constant stress tests, a kind of multiaxial fatigue test, was conducted on oligo‐crystalline 316L stainless steel thin wire, which was less than 3.5 grains across diameter of 200 μm. The material presents significant cyclic hardening under symmetric torsion cycling, and hardening is more obvious with the increasing shear strain amplitude. However, symmetric torsional cycle with constant axial stresses tests characterize rapid initial hardening and then gradually softening until fatigue failure. The axial stress has a great effect on torsional fatigue life. Fractography observation shows a mixed failure mode combined torsional fatigue with tensile strain because of axial tensile stress. A newly proposed model with axial stress damage parameter is used to predict the torsional fatigue life with constant axial stress of small scale thin wire.     

桥梁拉索用CFRP线材阻尼特性试验研究和理论分析

为获得用于桥梁的CFRP拉索的阻尼特性,用自由衰减振动试验方法测试了CFRP线材(CFRP丝)和高强度钢丝的阻尼值,根据应变能比例阻尼理论分析了其弯曲变形的能量损失系数。通过不同振动频率条件下的测试结果比较了CFRP丝和钢丝的阻尼特性及其与振幅之间的相关性。结果表明,两种材料的振动阻尼均随应变幅值的增加而单调增加,但两者的变化趋势有差异。在同一应变幅值条件下,CFRP丝的实测阻尼值比高强钢丝的小。高强钢丝的能量损失系数与振幅无关,验证了能量损失理论对高强钢丝材料的阻尼计算的适用性。但CFRP丝的能量损失系数实测结果较离散,且与振幅有一定相关性,在特定振幅范围内可采用能量损失理论计算CFRP丝的阻尼。