块体非晶合金剪切带的原子力纳米压痕行为

通过原子力显微镜(AFM)纳米压痕实验研究传统纳米压痕实验形成的Fe基非晶合金剪切带区域及未变形区域的变形;结合压痕形貌实时原位观测,探讨块体非晶合金塑性变形局域化的原因.结果表明最大载荷44.6μN下,材料的剪切带、剪切带间和未变形区域的AFM纳米压痕残余面积分别为3274.7、2976.5和2879.2nm2,对应的硬度分别为13.62、14.98和15.49GPa,剪切带区域的硬度值比未变形区域的硬度值降低了约10%,说明塑性变形过程中,过剩自由体积的产生使剪切带结构发生软化.     

Producing micro-droplet of dilute sulphuric acid on pure iron surface and observing its corrosion behaviour by atomic force microscopy

A simple method was presented to produce a micro-droplet of sulphuric acid on a pre-selected micro-zone on a pure iron surface with the tip of an AFM cantilever. The three-dimensional shape of the droplet was imaged with the AC non-contact mode of the AFM, and the liquid/solid interface was observed in situ during corrosion using the contact mode. The substrate surface beneath the droplet was lowered by approximately 19 nm after 3.6 ks of adhesion. This method has important implications for experimental studies of micro-zone corrosion or lubrication.     

原子力显微镜和白光干涉仪在表面材料测试中的应用研究

目的验证原子力显微镜和白光干涉仪分别在表面材料测试中的分辨率及其在不同类型表面材料测试中的适用性。方法分别采用原子力显微镜和白光干涉仪,对不同厚度级别的ZnO薄膜、石墨烯、磨斑等几种不同类型的表面材料进行了具体的测试研究。结果白光干涉仪10×镜头和50×镜头及原子力显微镜皆可以准确地测试百纳米级别的ZnO薄膜厚度,测得的膜厚分别为148.668、123.354、111.648 nm。原子力显微镜也可以准确地测出十纳米级别的ZnO薄膜厚度,测得的膜厚仅为6.152 nm,而白光干涉仪则不能测试出十纳米级别的ZnO薄膜厚度。原子力显微镜可以准确地测试出石墨烯片的大小、厚度和层数等三维数据,测得的厚度为0.665 nm左右,层数为单层或双层,而白光干涉仪则没有如此高的分辨率。白光干涉仪可以准确地测试出磨斑的宽度、深度等三维数据,测得的磨斑深度为4.245μm,而原子力显微镜则不适合测试表面如此粗糙的样品。结论原子力显微镜适合于测试相对光滑的表面材料的三维形貌和数据,如测试十纳米级别以上的薄膜厚度、超薄石墨烯片厚度和层数。白光干涉仪则适合于测试相对粗糙的表面材料的三维形貌和数据,如测试百纳米级别以上的薄膜厚度、微米级别磨痕深度等。     

镧和钇对氢气还原(W,Ni,Fe)复合氧化物粉末的影响

以喷雾干燥法制备的(W,Ni,Fe)复合氧化物粉末为原料,在700℃、保温90 min的条件下进行还原,研究了镧和钇对氢气还原(W,Ni,Fe)复合氧化物粉末的影响.采用XRD、高倍TEM和SEM分别对还原后的复合粉末进行了物相分析、晶粒尺寸计算和形貌观察,并对还原后复合粉末的Fsss粒度、比表面进行了测定与分析.研究结果表明:不加稀土元素时,还原粉末由钨和γ-(Ni,Fe)两相组成,添加一定量的镧或钇后,还原粉末中分别出现了新相La(Ni0.75W0.25)O3或Y(Ni0.75W0.25)O3;未添加稀土元素时,颗粒为球形,添加一定量的稀土元素时,颗粒变为近球形或多面体,并随着稀土元素含量的增加,稀土元素对颗粒形貌的影响增大;当90W-7Ni-3Fe复合粉末中的稀土元素含量为0～0.8%时,随着稀土元素含量的增加,粉末dBET粒度、Fsss粒度和晶粒尺寸均显著降低,且粉末的分散性也明显提高;当添加相同含量的稀土元素时,对粉末性能影响程度的大小顺序是钇＞La-Y(混合稀土)＞镧.     

织构化硅片表面的粘着行为

为研究织构化表面的粘着行为,采用电感耦合等离子体刻蚀技术在硅片表面进行柱状织构的构筑。使用扫描电子显微镜(SEM)和原子力显微镜(AFM)对织构化硅片表面的形貌进行观测,利用原子力显微镜进行粘着试验,并考察织构对表面粘着性能的影响规律。结果表明:经过织构化的硅片表面上形成了较为规整均一的柱状织构,在相同试验条件下与未织构面相比,织构面上的粘着力显著降低(下降了73%~77%),表明表面织构的存在减小了接触面积;当相邻织构间的距离一定时,具有较小直径的织构表面更有利于粘着力的减小;表面织构同时降低了范德华力和毛细力的大小,使范德华力减小了88%~89%,毛细力减小了62%~68%;无论是在未织构面还是织构面上,毛细力对表面粘着力的贡献均处于重要地位。     

多晶体钛拉伸变形表面褶皱的形成及晶粒变形

用原子力显微镜对多晶体钛拉伸塑性变形中表面褶皱的形成及单个晶粒的变形进行了连续观察和测量.结果表明,表面褶皱随着应变量的增加而增大,而凹凸的相对位置关系不随变形的进行而变化.从单个晶粒来看应变量在0.1附近时由于孪晶的形成产生了新的凹凸,但对整体的表面褶皱凹凸位置关系没有大的影响.表面平均粗糙度和表面最大高低差随应变量的增加近似呈直线性增大,应变量在0.1左右时由于孪晶的形成,使粗糙度有较明显的增大.     

碳化硼陶瓷的表面形貌和摩擦性能

用原子力／摩擦力显微镜对碳化硼样品进行了表面形貌的微观分析。在载荷为1—6μN下，研究了Si3N4探针扫描碳化硼表面时摩擦力的分布。结果表明：摩擦力的变化与扫描处的试样表面形貌有关，表面形貌变化斜率越大处，摩擦力增加得越多；由于试样较平整，摩擦力的分布是比较均匀的；碳化硼材料纳米摩擦因数随载荷的增加而显著增加。     

磁控溅射SiC薄膜表面形貌演化行为研究

采用射频磁控溅射法在石英玻璃基底上沉积SiC薄膜.用扫描电子显微镜(SEM)和原子力显微镜( AFM)观察薄膜的表面形貌,利用粗糙度和颗粒度大小对薄膜表面形貌动态演化进行量化表征.结果表明:在100～175 W溅射功率范围内,1 000℃高温真空退火处理能明显减小SiC薄膜表面粗糙度,膜层表面更为平滑,颗粒大小更为均匀...     

钛合金表面GO/纳米ZnO复合涂层的制备及性能

为了有效解决生物医用钛合金长期植入人体后,易发生细菌感染和面临有害金属离子释放的问题,采用水热反应和涂覆方法,分别在聚多巴胺(PDA)预处理的Ti6Al4V合金表面制备了氧化石墨烯涂层(GP/T)和氧化石墨烯/纳米氧化锌复合涂层(GZP/T)。系统分析了2种涂层的物相结构、微观形貌及其在林格氏液中的耐腐蚀性能和在大肠杆菌环境中的抗菌性能。结果表明:聚多巴胺发挥“双面胶”桥接作用,有效增强了涂层与基底间的化学键合;GP/T涂层抗菌率随着GO浓度增大而增大;GZP/T纳米复合涂层相较Ti6Al4V基材具有优异的耐蚀性,该复合涂层中ZnO起主要抗菌作用。     

原子力显微镜在马氏体相变浮突研究中的应用

用原子力显微镜在大气环境中对Ｆｅ－Ｎｉ－Ｃ合金中的马氏体浮突进行了观察和定量测量。结果表明，原子力显微镜既可清楚地观察浮突形貌，又可定量测量其高度和形状变化，从而提出了一种研究相变浮突的新方法。     

氧化石墨烯-壳聚糖复合物的制备及其吸附性能

采用Hummers法合成的氧化石墨烯(GO)与壳聚糖(CTS)制备复合型吸附剂GO-CTS,通过傅立叶红外光谱仪(FTIR)和扫描电镜(SEM)对结构和形貌进行表征。考察pH、投加量、吸附时间以及铀初始浓度等参数对吸附剂去铀效果的影响。结果表明,对于10mg/L的含铀溶液,GO和GO-CTS的最佳吸附条件分别为:pH=4~7,5;投加量1.0,1.0g/L;吸附时间为1,70min;最大去铀率分别为99.5%,97.5%。GO和GO-CTS的吸附平衡符合Freundlich等温线模型,表明为多分子层吸附,主要以物理吸附为主,最大吸附量分别为78.13和114.94mg/g。     

Strain-induced orientation of copper oxide nanoislands through decomposition of pre-organized copper nitrate

By the decomposition of copper nitrate at 400℃, oriented islands of copperoxide crystals were suceessfully fabricated on the amorphous glass surface. X-ray diffraction (XRD), atom force microscope (AFM), and X-ray photoelectron spectroscopy (XPS) confirm the presence of copper oxide islands. The formation of oriented island structures is attributed to the following reasons: 1) the mismatch between the glass substrate and the copper oxide crystals during the relaxation of thermal expansion leads to the formation of islands; 2) the preorganized copper nitrate particles in the voids of colloidal crystals determine their ordered spatial distribution; 3) the strain of the glass substrate developing during calcination provides the driven energy for the orientation of copper oxide crystals along the same direction.     

复合材料导电铝涂层的表面喷丸

在火焰喷涂过程中,金属Al的熔滴表面被氧化,在涂层中凝固时形成一层电绝缘的氧化物(Al2O3).同时涂层中的空隙都会影响Al涂层的导电性能.本文通过对涂层表面进行喷丸处理,从而细化熔滴颗粒,降低涂层孔隙率.提高涂层的导电性能.经过喷丸处理后的涂层,电阻可以减小至0.043mΩ,与未经过喷丸处理的涂层比较,电导率提高至1...     

A comparison of the corrosion behavior of WC-Co-Cr and WC-Co HVOF thermally sprayed coatings by in situ atomic force microscopy (AFM)

The corrosion behavior of WC-Co-Cr and WC-Co high velocity oxygen fuel (HVOF) sprayed coatings were examined in static saline conditions. Direct current (DC) polarization tests were conducted and the electrochemical corrosion behavior was shown, by in situ atomic force microscopy (AFM) and scanning electron microscopy (SEM), to be complex because of the composite ceramic-metal nature of the coating. The addition of chromium to the matrix greatly enhanced the corrosion resistance of the coating.     

Formation and capacitance properties of Ti-Al composite oxide film on aluminum

Al specimens were covered with TiO2 film by sol-gel dip-coating and then anodized in ammonium adipate solution. The structure, composition and capacitance properties of the anodic oxide film were investigated by transmission electron microscopy (TEM), Auger electron spectroscopy (AES), X-ray diffractometry (XRD) and electrochemical impedance spectroscopy (EIS). It was found that an anodic oxide film with a dual-layer structure formed between TiO2 coating and Al substrate. The film consisted of an inner Al2O3 layer and an outer Ti-Al composite oxide layer. The thickness of layers varied with the number of times of sol-gel dip-coating. The capacitance of anodic oxide films formed on coated specimens was at most 80% higher than that without TiO2. In film formation mechanism, it was claimed that the formation of composite oxide film was mainly affected by the structure of micro-pores network in TiO2 coating which had an influence on Al3+ and O2- ions transport during the anodizing.     

增强体含量对原位合成钛基复合材料微观组织及力学性能的影响

使用原位自生法制备出4种TC18钛基复合材料。结果表明,热处理过程中随着增强体含量增加,β晶粒的合并速度加快,且β晶粒的尺寸分布标准差呈现下降的趋势,该组织现象与增强体对β晶界迁移的影响有关。增强体对晶界迁移钉扎能力的下降是导致该细化规律的首要原因。TiB和TiC摩尔比为4:1的复合材料在拉伸试验中塑性俱佳,但是屈强比却均高于0.96,且随着增强体含量增加呈现增加的趋势。拉伸过程中晶界对位错的吸收致使位错强化增加减缓,增强体加速了晶界对位错的吸收从而导致了上述结果,也正因为如此,晶粒细化对增韧作用的贡献会随着增强体含量增加而增加。     

On the use of atomic force microscopy for structural mapping of metallic-glass thin films

In this article, we discuss the recent use of the high-resolution dynamic atomic force microscopy (DAFM) in mapping the nano-scale dynamical structural heterogeneity in thin film metallic-glasses (TFMGs). Our focus is laid on the major factors which can influence the structural contrast in the DAFM images, such as tip radius, free-amplitude, set-point amplitude and surface roughness. Finally, through a comparative study of different TFMGs and single-crystal silicon, we demonstrate that the DAFM technique is effective in distinguishing different nanostructures through their energy dissipation spectra.     

C_f/SiC复合材料与钛合金Ag-Cu-Ti-C_f复合钎焊

采用Ag-Cu-Ti-Cf(Cf:碳纤维)复合钎料作中间层,在适当的工艺参数下真空钎焊Cf/SiC复合材料与钛合金,利用SEM,EDS和XRD分析接头微观组织结构,利用剪切试验检测接头力学性能.结果表明,钎焊时复合钎料中的钛与Cf/SiC复合材料反应,在Cf/SiC复合材料与连接层界面形成Ti3SiC2,Ti5Si3和少量TiC化合物的混合反应层.复合钎料中的铜与钛合金中的钛发生互扩散,在连接层与钛合金界面形成不同成分的Cu-Ti化合物过渡层.钎焊后,形成碳纤维强化的致密复合连接层.碳纤维的加入缓解了接头的残余热应力,Cf/SiC/Ag-Cu-Ti-Cf/TC4接头抗剪强度明显高于Cf/SiC/Ag-Cu-Ti/TC4接头.