Energy dependent structure changes in ion beam deposited a-C:H

The present study investigates the effect of ion energy in the form of acceleration potential on the structure of ion beam deposited a-C:H films using Raman spectroscopy, FTIR spectroscopy and profilometry. The results indicate that for low acceleration potentials (100–200 V), the sp² fraction of the film becomes more ordered as the acceleration potential increases. However, FTIR indicates that the hydrogen bonding in the film is unaffected. For mid-range acceleration potentials (200–800 V) the film structure remains stable, then, as the acceleration potential is increased above 800 V there is a further increase in the order of the sp² fraction in the films and a change in the hydrogen bonding in the film. These structure changes suggest that two separate energy dependent processes effect the structure of IBD a-C:H; a densification/relaxation process at low acceleration potentials and ion damage/sputtering processes at higher acceleration potentials.     

超音速微粒轰击对冷轧态Fe-28Mn-8Al-1C低密度钢组织和性能的影响

为了实现冷轧态低密度钢强度与塑韧性的良好匹配及优良的表面完整性,提升车辆行驶过程中的可靠性和安全性,延长其在服役环境下的使役寿命,通过超音速微粒轰击（SFPB）技术对冷轧态Fe-28Mn-8Al-1C低密度钢进行表面纳米化处理,借助扫描电镜（SEM）、透射电镜（TEM）、X射线衍射仪（XRD）、显微硬度计、万能材料试验机等测试手段,系统研究SFPB冲击时间及气体压力对其表面形貌、微观结构和力学性能的影响。研究结果表明：SFPB处理可在冷轧态Fe-28Mn-8Al-1C低密度钢表面形成梯度纳米结构,可将表层晶粒尺寸细化至纳米量级,在气体压力为1.0 MPa,冲击时间为120 s时,相应的强度指标达到最大值。随着冲击时间的延长和气体压力的增大,表层纳米晶尺寸逐渐减小,相应的显微硬度值及严重塑性变形（SPD）层深度也随之增大。然而,冲击时间过长或气体压力过大会导致表层微裂纹的形成,致使其强度指标降低。不同SFPB工艺参数下的冷轧态Fe-28Mn-8Al-1C低密度钢伸长率未发生明显变化,拉伸断口形貌均表现为韧-脆混合型断裂特征。SFPB技术通过在低密度钢表面构筑梯度纳米结构,能实现低密度钢组织性能的可控制备,同时在诱导背应力强化以及残余压应力抑制裂纹萌生和扩展的耦合作用下,能有效提升低密度钢的综合力学性能,可为其在汽车领域的生产及应用提供参考。     

超音速微粒轰击对GCr15SiMn轴承钢表面纳米化与摩擦磨损性能的影响

目的 利用超音速微粒轰击对GCr15SiMn轴承钢表面进行强化处理,并研究超音速微粒轰击对材料表层组织、力学性能及摩擦磨损性能的影响。方法 采用三维显微形貌仪、透射电镜、背散射电子仪、扫描电镜、X射线残余应力分析仪、显微硬度仪等仪器观测GCr15SiMn轴承钢强化前后的微观组织、表面粗糙度、力学性能,并使用UMT-2摩擦磨损试验机对试样强化前后的摩擦磨损性能进行检测。结果 经过超音速微粒轰击强化处理的GCr15SiMn钢试样的表面粗糙度增加,表层结构发生严重的塑性变形,形成约20 μm厚的塑性变形层,片状马氏体细化至纳米级,平均晶粒尺寸约为13 nm,碳化物平均粒径由0.48 μm减小到0.45 μm,数量增加了约18%。试样表层引入了300 μm的硬化层,表面硬度从740HV0.05提高到了996HV0.05,距表面10 μm处出现硬度最高值为1 056HV0.05,硬度提高了42.7%。试样引入深度为60 μm的残余压应力层,样品表面残余应力为‒1 246 MPa左右。经过超音速微粒轰击后,强化试样平均摩擦因数略高于原始试样,而磨损率得到了大幅度降低,磨损机理主要为磨粒磨损,伴有少量的氧化磨损和黏着磨损。结论 经过超音速微粒轰击的GCr15SiMn轴承钢表面粗糙度增加,表层晶粒细化至纳米级;表层构建了残余应力层和硬化层;强化引入的残余应力和因强化处理引起的加工硬化、细晶强化改善材料的耐磨性。     

How tantalum proceeds phase change on tantalum nitride underlayer with sequential Ar plasma treatment

Tantalum can change its phase from high resistive β-Ta to low resistive α-Ta phase on a TaN substrate with sequential Ar plasma treatment on the TaN layer surface prior to Ta deposition. The underlined mechanism of phase evolution is proposed based on systematic microstructure examination by high-resolution transmission electron microscopy. The images show that, with argon treatment, the upper part of the TaN film is transformed from amorphous-TaN to a composite phase of bcc-Ta(N) and amorphous-TaN mixture, which is also confirmed by X-ray diffraction patterns. The composite film composed of less nitrogen provides an ideal cubic matrix to confine the stable α-Ta phase to be grown. The α-Ta/bcc-Ta(N) film obtained by proper argon treatment results in film resistivity 10 times lower than the traditional Ta/TaN film.     

“LonWorks”现场总线技术的新发展

Internet作为一个全球性的巨大的计算机网络体系,解决了人类交互通信的诸多难题.如何将全球的工业现场生产设备也能联接为开放的、点对点的、可互操作的计算机网络系统,从世界的任何角落都能对现场设备进行远程遥控,LonWorks现场总线技术为设计、创建、安装和维护这种设备控制网络方面的许多问题提供了简捷方便的解决方案.本文介绍这种现场总线技术的形成和发展、特点和优缺点、核心技术和网络自由拓扑结构以及它的开发应用、展望与新发展趋势.     

Quantitation of Benzo(a)pyrene-glucuronic Acid Conjugates Formed in Benzo(a)pyrene Treated Cell Cultures by Continuous-flow Fast Atom Bombardment Mass Spectrometry

Glucuronic acid conjugates of phenolic benzo(a)pyrene metabolites (BP-glucuronides) were determined by continuous-flow fast atom bombardment mass spectrometry (continuous-flow FABMS). BP-glucuronides were isolated from the medium of BP-treated cell cultures by solvent/solvent extraction and microbore HPLC. A continuous-flow FABMS method was used for determining the amount of BP-glucuronides. Very high selectivity was achieved by using a mass resolving power of M/ΔM of 10000. Five picograms of BP-glucuronide gave a response with a signal-to-noise ratio of 10:1. Early passage hamster embryo cell cultures metabolized 18% of the BP to BP-glucuronides, while the mouse hepatoma cell line Hepa-lclc7 metabolized 25% of the BP to BP-glucuronides. In contrast, the amount of BP-glucuronides present in medium samples from BP-treated cultures of the human hepatoma cell line HepG2 was below the detection limits of the method (less than 0.5 ng per mL of medium).     

M型阴极离子斑扫描电镜分析

采用扫描电镜及X射线能谱仪对覆膜阴极的离子斑进行了分析。分析表明,阴极离子斑中心部分的贵金属覆膜(Os膜)已被完全溅射掉;离子斑周边覆膜仍保留一部分,但Ba和O的含量极低。进一步分析表明,离子轰击不仅使离子斑区域贵金属膜受损,同时使该区域Ba-O键的含量大幅度降低,从而导致该区域及整个阴极的发射出现明显下降。     

用基因枪将P1结构蛋白基因转入玉米及其转基因植株再生研究

在构建口蹄疫病毒(Foot and Mouth Disease Virus,FMDV)结构蛋白P1基因植物表达载体pBIl31SPl的基础上,以玉米自交系8902、340和4112的Ⅱ型胚性愈伤组织为受体,用基因枪轰击法转化玉米,获得抗性再生植株。GUS染色证明外源目的基因在玉米细胞和组织中得到了表达。PCR检测、PCR-Southern杂交、点杂交鉴定证实目的基因P1已整合到再生植株的基因组中,获得了转基因玉米再生植株。     

循环氩离子轰击对磁控溅射铝膜结构和性能的影响

为了提高烧结钕铁硼永磁材料的耐腐蚀性能,采用磁控溅射技术在钕铁硼表面制备了厚度约为14.0μm的铝膜,使用循环氩离子轰击铝膜的方法制备了3个周期的多层铝膜。利用扫描电子显微镜(SEM)观察铝膜的表面和截面形貌,X射线衍射仪(XRD)表征膜层的晶体结构,采用中性盐雾试验测试膜层的耐盐雾腐蚀性能,研究循环氩离子轰击对铝膜层形貌、结构及耐中性盐雾腐蚀性能的影响。结果表明:与相同厚度的单层铝膜相比,3个周期的多层铝膜晶粒均匀细小,膜层的柱状晶结构被打断,内部形成了两个明显的界面;膜层沿(111)晶面择优生长;与厚度相同的单层Al膜相比,3个周期的多层Al膜的耐蚀性显著提高,其耐中性盐雾腐蚀时间可达到312h。循环氩离子轰击铝膜的方法可以改善铝镀层的质量和耐盐雾腐蚀性能。     

超音速微粒轰击诱导表面纳米化对TC11钛合金组织和力学性能的影响

采用超音速微粒轰击(SFPB)表面纳米化技术,在TC11钛合金表层构筑了一定层深的梯度纳米结构,研究了SFPB气体压力对TC11钛合金微观组织和力学性能的影响。结果表明,在低气体压力(0.5 MPa)下,形成了25 μm厚的严重塑性变形层,表层晶粒细化至纳米量级(17.7 nm)。随着气体压力的增大,表层纳米晶尺寸降低,严重塑性变形(SPD)层增大,在高气体压力(1.5 MPa)下,表层纳米晶尺寸和严重塑性变形层深度分别为9.4 nm和51 μm。随着SFPB气体压力的增大,表层显微硬度及硬化层深度逐渐增加,屈服强度、抗拉强度显著增加,而伸长率变化不大,断口形貌从典型的韧性断裂向韧-脆性混合断裂转变。