电沉积制备纳米晶Fe-Ni-Mo合金箔

在酸性柠檬酸盐-氯化物体系中电沉积纳米晶低钼高铁Fe-Ni-Mo合金箔, 探讨了电沉积的工艺条件对合金组成的影响规律, 并确定了制备低Mo高Fe含量的纳米晶Fe-Ni-Mo合金箔的电解液组成和工艺条件。 通过SEM、XRD和EDS对合金箔的表面形貌、微观结构和组成进行表征, 结果表明: 合金箔表面平整, 结构致密, 无孔洞及裂纹, 晶粒属于纳米晶, 晶粒尺寸随电流密度、pH值和温度的下降而减小。合金箔为FeNi置换固溶体, 面心立方晶体结构, 呈现很强的(111) 和(200)晶面择优取向。     

电沉积Ni-W合金纳米晶的组织与性能

通过电沉积方法镧备Ni-W合金纳米晶，研究钨酸钠浓度、电流密度、镀液pH、温度等四个工艺参薮对Ni-W合金沉积速率、星徽硬度、镀层表面质量的影响。结果表明，通过控镧钨酸钠浓度，可获得不同尺度的Ni-W合金纳米晶，随电流密度增加，镀层的沉积速率和星徽硬度提高。镀液的pH对镀层性能影响最大。Ni-W合金纳米晶镀层具有较高的抗腐蚀性。     

电沉积制备选区激光熔化用金属基纳米复合材料

以镍为基础金属,分别采用纳米氧化铝(Al_2O_3)、碳化硅(SiC)、氧化锆(ZrO2)和氧化钇(Y_2O_3)颗粒,使用电沉积法制备了选区激光熔化用的金属基纳米复合材料。研究了电沉积法制备的不同纳米颗粒在分散和掺入分数方面的影响,进一步研究了电沉积参数对Ni/Al_2O_3纳米复合材料的影响。结果表明,当Al_2O_3浓度为10g/L、超声振幅为23μm的条件下,效果最佳。显微硬度测试表明,纳米Al_2O_3的加入显著提高了镍基合金的力学性能,Ni/Al_2O_3纳米复合材料的平均维氏硬度(HV0.05)为267.1kg/mm~2,比纯镍的平均维氏硬度(153.9kg/mm~2)增强了73.6%。选区激光熔化后纯镍表面粗糙度从254nm减小到107nm,而Ni/Al_2O_3纳米复合材料表面粗糙度从323nm减小到72nm。同时Al2O3粒子能够均匀分布,无明显团聚现象。     

电沉积法制备纳米铜粉的研究

研究了在摩尔比为2∶1的尿素-氯化胆碱(Urea-Ch Cl)低共融溶剂(DES)中,将氧化亚铜溶解在该体系中,采用恒电位电沉积法,制备出了颗粒尺寸在40 nm左右的纳米铜粉。通过单因素条件试验,结合扫描电镜(SEM)分析及电流效率分析,确定电沉积制备纳米铜粉的最佳试验条件为:阴极材料为镍片,电解液温度为313~323 K,槽电压为2.5 V,电沉积时间为2 h。     

超声场中电沉积制备纳米晶Ni-SiO2

于恒定功率超声场中,采用优选的电沉积工艺参数,制备出纳米晶Ni-SiO2复合层。借助显微硬度计和质量损失法测定复合层的性能。结果表明,显微硬度和耐酸性均较常规Ni-SiO2复合层提高,但受阴极电流密度影响明显。随阴极电流密度增加(2~14 A/dm2),显微硬度近似呈线性增大趋势,最高达461.3 HV,耐酸性先改善后削弱,在10%HCl溶液中的腐蚀速度从0.008 8 mg/mm2.d减至0.007 1 mg/mm2.d后增至0.009 3 mg/mm2.d,在10%H2SO4溶液中的腐蚀速度从0.008 1 mg/mm2.d减至0.006 6 mg/mm2.d后增至0.008 2 mg/mm2.d。     

脉冲电解法制备纳米晶金属镍的摩擦性能

采用脉冲电解沉积工艺制备厚度约60μm的金属镍薄膜.当脉冲电流密度为7.5×10-2A/m2,通断时间比为1/25,pH=4.5,T=50℃时,所制备镍薄膜的平均晶粒尺寸约20nm,硬度为637HV.在电流密度一定时,晶粒尺寸随脉冲通断时间比减小而变小,硬度增大.与常规粗晶镍材料相比,纳米晶体结构镍薄膜的耐摩擦性能得到显著改善,在恒定压力下滑擦5次,纳米晶体结构镍薄膜的磨损深度从25nm增加到30nm,摩擦系数在0.13～0.20之间,而粗晶镍薄膜的磨损深度从35nm增加到46nm,摩擦系数在0.19～0.31之间.     

超细晶/纳米晶钨材料制备技术的研究进展

晶粒细化可显著提高超细晶/纳米晶钨材料的性能,介绍了超细晶/纳米晶钨材料制备技术的最新研究进展,包括粉末冶金法和深度塑性变形法,粉末冶金法的烧结工艺主要包括热等静压烧结、超高压通电烧结、放电等离子体烧结、微波烧结等;深度塑性变形法包括高压扭转、等通道挤压、表面机械研磨处理和累积轧制等。由于超细晶/纳米晶钨材料存在大量的晶界可有效提高材料的力学性能和抗辐照性能,因此有望解决纯钨材料作为核聚变堆面向等离子体材料存在的问题,对超细晶/纳米晶钨材料的发展提出了建议。     

电沉积镍铁合金工艺研究

选择对镍铁合金镀层组成影响较大的硫酸镍浓度、硫酸亚铁浓度、电流密度温度等４个工艺参数进行正交回归实验,用电镜扫描分析法测得镀层铁含量求出了回归方程,数理统计分析表明回归方程可靠适用。根据回归方程,作出了工艺参数与镀层铁含量关系曲线并进行了讨论。     

电沉积法制备超细高纯铜粉

以Cu SO4溶液为主要原料,采用电沉积法快速制备高纯超细铜粉。利用X射线衍射仪(XRD)和扫描电镜(SEM)表征铜粉的粒度和微观形貌。结果表明,阴极材质和超声波对铜粉的微观形貌和粒度均具有重要影响,超声波可有效降低铜粉的平均粒径,铝材质阴极形成粒度范围0.01~0.5μm的球形铜粉,铁材质阴极形成粒度范围为0.1~1.5μm的不规则球形和方形铜粉。     

替代电镀铬SiC复合镀电沉积机理综述

利用SiC复合镀层代替硬铬电镀来改善材料的耐磨性能,可有效解决电镀硬铬所带来的严重污染问题。有关SiC复合电沉积机理研究,国内外学者提出了不同的观点。综述了最具有代表性的几种固体颗粒与金属的共沉积机理。Guglielmi模型应用最为广泛,但是该模型未考虑电吸附和电动力学方面,存在严重局限性。Celis的模型更为完整,但模型建立的过程中采用了许多限制性的前提条件。Valdes模型存在与Guglielmi模型类似的弊端,很难做出定量分析。运动轨迹模型则适用范围较窄。虽然每种机理都有其合理性和局限性,尽管颗粒的表面电荷和电解质对于复合电沉积非常重要,但实际表征手段的发展非常缓慢,导致对复合电沉积机理的理解相对缓慢,希望未来关于复合电沉积的机制发展可以综合考虑不同类型的速率控制、流动条件、颗粒特性和不同的操作变量。     

Influence of inhomogeneity of grain-boundary region of nanocrystalline materials on elastic properties

Experimental data indicate that Young''s modulus of materials decreases with the decreasing of the grain size. Obviously, the primary factor of this decrease is presence of grain-boundary region, which Young''s modulus other than in the bulk of crystallites. There is a set of various expressions for calculation of Young''s modulus of polycrystals, obtained under the assumption, that it is possible to consider a polycrystal as a composite consisting of a crystalline matrix and a intercrystalline layers (grain-boundary region). Calculations showed incorrectness of application of a majority of these expressions and a large error in the calculations for the nanocrystalline materials. By us, on the basis of the same assumptions, is also obtained analytical expression for calculating Young''s modulus of materials with grain size more than 30 nm, which is more exact, than all others.It is necessary to consider under the calculation of effective Young''s modulus nanocrystalline materials with grain size of less than 30nm, that grain-boundary region itself is not uniform. It is reliably established,that the triple joints of grain boundaries have a structure and properties, different from the structure and the properties of grain boundaries, which these joints connect. For nanocrystalline materials the volume fraction of the triple joints in the grain-boundary region can reach 50, and even more. Therefore assumption was made, that the nanocrystalline materials should be represented as consisting of three phases (triple joints,grain boundary between the triple joints and crystallite). On the basis of this idea is obtained analytical expression for calculating of Young''s modulus nanocrystalline materials. The analysis shows that Young''s modulus calculated by this analytical expression coordinated with the theory and the experiment.     

Influence of inhomogeneity of grain-boundary region of nanocrystalline materials on elastic properties

Experimental data indicate that Young‘s modulus of materials decreases with the decreasing of the grain size. Obviously, the primary factor of this decrease is presence of grain-boundary region, which Young‘s modulus other than in the bulk of crystallites. There is a set of various expressions for calculation of Young‘s modulus of polycrystals, obtained under the assumption, that it is possible to consider a polycrystal as a composite consisting of a crystalline matrix and a intercrystalline layers (grain-boundary region). Calculations showed incorrectness of application of a majority of these expressions and a large error in the calculations for the nanocrystalline materials. By us, on the basis of the same assumptions, is also obtained analytical expression for calculating Young‘s modulus of materials with grain size more than 30 nm, which is more exact, than all others.It is necessary to consider under the calculation of effective Young‘s modulus nanocrystalline materials with grain size of less than 30nm, that grain-boundary region itself is not uniform. It is reliably established,that the triple joints of grain boundaries have a structure and properties, different from the structure and the properties of grain boundaries, which these joints connect. For nanocrystalline materials the volume fraction of the triple joints in the grain-boundary region can reach 50% and even more. Therefore assumption was made, that the nanocrystalline materials should be represented as consisting of three phases (triple joints,grain boundary between the triple joints and crystallite). On the basis of this idea is obtained analytical expression for calculating of Young‘s modulus nanocrystalline materials. The analysis shows that Young‘s modulus calculated by this analytical expression coordinated with the theory and the experiment.     

金属材料及热处理实验的探讨

1 对无屈服点的压缩试件材料的鉴别 材料力学实验中的低碳钢压缩试件,要求测出屈服时载荷P_s,计算屈服极限σ_s。 我院材料力学实验室有批早期加工的碳钢压缩试件。从加工质量看:试件的尺寸在规定的范围内,即1≤h/d≤3(h——试件高度;d——试件直径),试件两端面平行,并且与轴线保持垂直(见图1)。     

碳纳米管超级电容器的研究进展

综述了碳纳米管超级电容器的研究进展,并介绍了采用碳纳米管作为超级电容器电极材料的优缺点及制备高性能碳纳米管超级电容器的方法.     

金属矿山酸性废水处理技术研究进展

概述了矿山酸性废水的形成及危害,重点介绍了几种常见的处理矿山酸性废水的处理技术如中和法、硫化物沉淀法、吸附法、离子交换法和人工湿地法,同时介绍了它们的原理、特点和存在的问题,在此基础上,对矿山酸性废水处理技术的研究进行了展望。     

近代数学方法在材料科学中的应用及进展

近代数学是一门正处于迅速发展的新学科 ,其应用领域和影响范围在不断扩大 ,综述了近代数学方法在材料科学研究中的应用 ,重点介绍了分形理论在材料制备、薄膜生长和材料表面的应用以及小波分析在材料检测、混沌理论在材料制备方面的应用及研究进展情况。     

Al基金属相变储能材料的研究与应用进展

对Al基金属相变储能材料在国内外的研究状况、液态腐蚀性、与容器材料的相容性和应用等方面作了综合介绍.     

Al基金属相变储能材料的研究与应用进展

对Al基金属相变储能材料在国内外的研究状况、液态腐蚀性、与容器材料的相容性和应用等方面作了综合介绍.     

金属硼化物在Li-S电池正极载体材料中的研究进展

锂硫（Li-S）电池因其高的能量密度、较低的生产成本和环境友好性能而受到广泛关注。其中正极载体材料的合理设计与合成成为解决当前Li-S电池所面临的缓慢反应动力学、实际电池容量及库伦效率低及循环稳定性不足的关键。金属硼化物对多硫化物因具有良好的化学吸附/催化性能,从而在Li-S电池正极载体材料中得到广泛关注。本文详细介绍了一系列典型金属硼化物如MgB2、Co2B、TiB2、MoBx、ZrB2在Li-S电池正极载体材料中的应用,阐述了不同材料提高Li-S电池性能的方法和策略,并且深入分析了其独特的电化学作用机制。本综述为设计与合成Li-S电池用金属硼化物高效正极载体材料提供了指导。