电石渣热处理条件对合成超轻硬硅钙石的影响

采用DTA/TG研究了电石渣的热处理性能,采用XRD及SEM等检测手段,研究了经不同温度煅烧后电石渣的矿物组成、形貌以及热处理条件对石灰活性及合成硬硅钙石的影响。结果表明,电石渣经适当煅烧处理后可以作为钙质原料制备超轻硬硅钙石。不同电石渣煅烧温度对合成产物的晶相组成没有影响,但对石灰活性及合成产物的微观形貌有较大的影响。700、800℃煅烧电石渣制备的石灰乳活性大,合成得到的硬硅钙石粒子球形度完整;而900、1000℃煅烧电石渣制备的石灰乳活性小,合成得到的硬硅钙石球形粒子直径小,且倾向于紧密团聚。     

工艺参数对超级钢焊接温度场的影响

对不同焊接速度情况下的超级钢焊接温度场进行了数值模拟及有限元分析,定量对比分析了焊接速度对焊接温度场的影响.同时,对不同焊接电流、电压情况下,超级钢焊接温度场进行了数值模拟及有限元分析,定量对比分析了电流电压对焊接温度场的影响.     

Study on improving properties of welded joints of 400 MPa ultra fine grained steel by mechanical surface hardening

The welded joints of 400 MPa ultra fine grained steel in manual arc welding were treated by mechanical surface hardening. Microstructure and mechanical properties of the treated joints were compared with those of the untreated joints, based on which, primary study on the process and principle of mechanical surface hardening was carried out. The results shows that： Grain size of HAZ increases greatly and mechanical properties of welded joint decrease obviously compared with those of base martial, but grain size in the surface layer of HAZ can be refined （the grain size is about 100 nm or so） and mechanical properties of welded joints can be improved greatly by mechanical surface hardening.     

焊接热输入对800MPa超级钢焊接接头组织性能的影响

对800 MPa超级钢不同焊接热输入作用下HAZ组织和性能进行了研究.结果表明,800 MPa超级钢在焊接热循环作用下HAZ晶粒明显长大,随着焊接热输入的增大,晶粒长大的趋势越显著;HAZ包含有超低碳贝氏体和细小铁素体等组织,过热区组织在焊接热循环的作用下变化明显,是断裂裂纹的发源地;不同焊接热输入下,整个HAZ的硬度...     

Prediction of HAZ grain size in welding of ultra fine grained steel with different parameters

The temperature field and thermal cycling curve in the heat-affected zone during welding 400 MPa ultra fine grained steel by plasma arc were simulated using finite element method.The principle of grain growth kinetics was used to predict the grain size in the heat-affected zone under different welding parameters.The simulation results show that the growing tendency of HAZ grain could be controlled by adjusting the welding parameters,but the growth of HAZ grain could not be eliminated at all.The HAZ grain size became small with increasing of the cooling rate and added with increasing of welding current,arc voltage and welding speed.     

电沉积法制备的超细晶薄铜板拉伸及表面层效应

利用电沉积方法制备了晶粒大小均匀、致密的细晶薄铜板材料,研究了其在室温单向拉伸试验中由于晶粒大小、厚度变化引起材料强度和塑性的变化,通过表面层效应对产生的尺度效应进行了分析.随晶粒度的增大,材料的塑性和流动应力都发生了降低,这是由于表层晶粒所占份额增加.而且,由于表面层效应,随着试件厚度的减少,材料的流动应力降低.     

不同焊接电流电压下超级钢热影响区晶粒尺寸的数值模拟

.利用工程模拟软件模拟超级钢焊接温度场,在温度场模拟过程中对工件进行三维有限元网格划分,焊缝及热影响区等重要部位网格划分细密,离焊缝较远位置网格可适当稀疏.热源模型采用双椭球分布模式,利用计算机语言编制热源程序.从模拟温度场中提取热熔合线和焊接热循环曲线等信息,并实验加以验证,实验结果与模拟结果基本吻合.在热影响区温度场基础上,结合晶粒长大动力学原理计算热影响区晶粒尺寸,并实验加以验证,实验结果与计算结果基本吻合.利用此方法计算不同焊接电流、电压下热影响区晶粒尺寸,绘制晶粒尺寸图,定量预测了晶粒尺寸随电流、电压增加而增大的趋势.     

精密垫片精冲模设计

分析了精密垫片的冲压工艺性,为了提高垫片的冲裁质量,采用精密冲裁工艺生产。通过冲裁力、压边力、反压力等计算,确定模具类型和冲压设备。设计了精冲模具结构,论述了模具工作过程及齿圈的设计要点。该模具结构简单,运行平稳,性能可靠,使用寿命长,生产效率高。生产实践证明:采用该种精冲工艺生产,产品毛刺极小,断面平整光滑,质量稳定,达到规定的精度要求。     

立式搅拌细磨难处理银厂尾矿

采用实验室型立式搅拌磨机将银厂尾矿进行超细磨碎。试验证明,将尾矿超细磨碎能大幅度提高尾矿氰化浸出银的提取率,从细磨前尾矿（d 80为100μm）中银的浸出率36%提高到细磨后（d 80为1.2μm）的84%。在超细磨试验中,通过Box-Behnken设计,研究了磨球直径（2-4.5 mm）、搅拌速度（200-800 min/min）和球料比（50%-80%）对研磨细度的影响。结果表明,提高搅拌速度和球料比降低了磨料细度,使用较大的磨球会得到较粗大的产品。在适当的条件下,可以得到细度小于5μm的磨料。应力强度分析表明,应力强度范围（0.8-2）×10^-3 N·m是合适的。     

超快冷却技术的发展

介绍了在加速冷却技术、直接淬火技术和机架间冷却技术之后的又一种新的控制冷却技术———超快冷却技术 ;重点介绍了超快冷却技术的机理、超快冷却系统的构成、工艺参数及其应用实例     

等通道转角挤压制备超细晶材料的最新研究进展

等通道转角挤压(Equal channel angular pressing,ECAP)方法是制备性能优异超细晶材料最常见的大塑性变形方法之一。模角、挤压路径、挤压道次、挤压温度和挤压速度等因素都会影响等通道转角挤压制备超细晶材料的性能;等通道转角挤压的模具也在不断地优化,如背压-等通道转角挤压(Back pressure ECAP,BP-ECAP)模具、可加热的模具以及在等通道转角挤压基础上形成的板材连续剪切技术等,这些新的模具可以改变ECAP变形过程中的组织均匀性。本文综述了等通道转角挤压制备超细晶材料的最新研究进展,并指出了几个需要深入研究的问题及方向。     

超高强铝合金的显微组织

全面地介绍和评述国内外关于Al-Zn-Mg-Cu系铝合金显微组织的研究状况。Al-Zn-Mg-Cu合金的显微组织主要由基体析出相（MPt）、晶间析出相（GBP）、晶界无析出带（PFZ）和抑制再结晶化合物（过渡族元素化合物）组成，它们几乎影响着合金的所有宏观性能。因此，控制了显微组织中的基体析出相、晶间析出相、晶界无析出带和抑制再结晶化合物的大小、分布及均匀性就控制了性能，而实现控制的主要途径是热处理。     

Tribological properties of brake friction materials with steel fibers

The tribological properties of brake friction materials with and without steel fibers were investigated. The focus of this study was determining the effect of steel fibers on the speed sensitivity of the friction coefficient. The speed sensitivity of the friction coefficient is closely associated with the stick-slip phenomenon. The results indicate that the friction material containing steel filbers was more sensitive to sliding speed, exhibiting a highly negative μ-ν relation. In particular, the friction material with steel fibers showed a larger vibration amplitude during brake applications, suggesting that the μ-ν relation was strongly related to the friction-induced vibration. On the other hand, the wear resistance of the friction materials containing steel was significantly better than that without steel fibers, suggesting longer service life. A possible mechanism of the stick-slip by the steel fibers is discussed in terms of the physical properties of the steel fiber and the gray iron rotor.     

从“2012株洲硬质合金国际学术会议”论文看硬质合金行业现状与发展趋势

2012株洲硬质合金国际学术会议于2012年9月在湖南株洲召开,众多国内外专家、学者参加了会议。会议就硬质材料科学,相关的粉末及粉末冶金工艺,表面工程,建模、表征与测试等方面进行了广泛的学术交流。本文根据会议学术交流内容总结了硬质合金行业现状,探讨了当前硬质合金的前沿研究方向,指出硬质合金结构设计和使用技术研究具有极为重要的地位,而重视检测技术与表征为硬质合金的深入研究和开发奠定了良好的基础。     

精冲压力机的现状及发展趋势

首先介绍了精冲工艺对精冲压力机提出的几个基本要求,阐述了精冲压力机的结构特点。同时展示了目前国内外精冲压力机的生产和研究现状,并对精冲压力机的几个关键技术:滑块的导向精度和刚性、上死点精度控制技术和台阶式内阻尼静压导轨技术等进行了论述。然后根据目前的精冲工艺发展趋势,提出了精冲压力机的主要研究方向:有限元模拟及优化技术、电液控制技术、适应于高强度和厚板的精冲压力机。最后,指出高速、高效、柔性、智能化是未来精冲机的发展趋势,凭借其少无切削的精加工特点,将会在未来的制造业中发挥更大的作用。     

Aging of surface properties of ultra high modulus polyethylene fibers treated with He/O2 atmospheric pressure plasma jet

To investigate the relationship between aging of the treatment effect and the gas composition of atmospheric pressure plasma treatment, ultra high modulus polyethylene (UHMPE) fibers were selected as a model fiber to study the aging behavior of fiber surface treated by atmospheric pressure plasma jet (APPJ) with pure helium, helium + 1% oxygen, and helium + 2% oxygen. Atomic force microscopy showed increased surface roughness, while X-ray photoelectron spectroscopy revealed increased oxygen contents after the plasma treatments. The plasma treated fibers had lower contact angles and higher interfacial shear strengths to epoxy than those of the control fiber. Adding 1% of O₂ to helium increased effectiveness of the plasma in polymer surface modification and suppressed aging after the treatment, while adding 2% of O₂ had a negative effect on the APPJ modification results and accelerated aging. In addition, no significant difference in single fiber tensile strength was observed between the control and the plasma treated fibers.     

水溶液体系中制备纳米银线的研究

在水溶液体系中,以蔗糖为还原剂、NaCl为前驱体络合剂、PVP为表面活性剂,通过水热反应制备得到了直径大约为40 nm,线径分布均匀、分散性良好的纳米银线。有效解决了目前多元醇有机体系下制备纳米银线洗涤困难,反应条件苛刻,后处理繁琐等问题。系统研究了还原剂用量、还原剂种类、Cl^-/Ag⁺摩尔比、卤化物种类和表面活性剂种类对于产物形貌的影响。结果表明,当还原剂蔗糖的用量为0.18 g,PVP的相对分子质量为58000,选择Na Cl作为络合剂,且Cl^-/Ag⁺摩尔比控制在1.26时,制备的纳米银线形貌均一,纯度较高,纳米线长径比大于1000。     

High-temperature thermal conductivity of ceramic fibers

The ceramic fibers VK-60, ABK, and VK-80 produced by steam blowing and nozzle dissemination methods have been investigated for the effect of nonfibrous material content, pressure, and temperature on the thermal conductivity at ambient and higher temperatures. It was noticed that with an increase in the aluminum content of the ceramic fibers the thermal conductivity of the material decreased while the insulation properties improved. The VK-80 fibers have the lowest and the VK-60 fibers the highest value of thermal conductivity at ambient temperature. At ambient temperature, the value of thermal conductivity increased with an increase in pressure for all analyzed fibers. ABK fibers showed the least increase and VK-80 registered an increase of about 10% in the values of thermal conductivity for pressures ranging from 0.6 to 6.6 kN/². However, beyond a pressure of 6.6 kN/m², the thermal conductivity of all samples increased. To assess the insulation properties of investigated fibers, the thermal conductivity was measured at different temperatures up to 800 °C. From the obtained results, it was concluded that all three types of fibers have a good potential for future applications, showing good performance in the investigated temperature range.     

普通低碳钢形变诱导铁素体晶内和晶界的析出行为

利用TEM，萃取和X－ray衍射方法分析了利用形变诱导铁素体和铁素体再结晶机制获得超晶铁素体的晶内和晶界析出碳化物的成分和析出行为，证明晶内以M3C形成弥散析出，晶界面以层片状形式析出和碳为短程扩散行为。     

速度对极薄铝箔轧制的影响

将有限元静力分析软件ANSYS/Multiphysics对铝箔轧机辊系的计算结果——工作辊辊形作为已知辊形,利用有限元显式动力分析软件ANSYS/LS-DYNA,将工作辊视为刚性体,轧件作为变形体,分别模拟了0.045mm入口厚度的铝箔在不同轧制速度时的轧制过程,得到了不同的出口板厚分布及板形值,分析了速度变化对极薄铝箔轧制的影响,提出了极薄铝箔轧制宜采用的最佳速度制度。