Fabrication of Binary Niobium Alloys with Low-Melting Metals by the Deposition of Nanoparticles

Binary alloys of niobium with tin, lead, and cadmium are fabricated by the deposition of nanosized metal particles atomized in low-pressure plasma using the thermal-fluctuation melting effect. This effect implies the residence of a small particle in a quasi-liquid state to a certain critical size which, if is exceeded due to vapor condensation or merging (coalescence) with other quasi-liquid particles, leads to the droplet crystallization. Critical sizes are found at which the particles situated in a quasi-liquid state are able to coalescence and formation the alloy–solid solution. They are 2.1–2.2 nm for Nb, 0.4 nm for Sn, 0.6 nm for Pb, and 3.2 nm for Cd. The occurrence boundary of solid solutions of metals in niobium is determined by the following concentrations, at %: Sn 25.5, Pb 23.0, and Cd 64.5. The solid solution is based on the crystal lattice of matrix metal—niobium, in which lead, cadmium, and tin atoms are arranged. In connection with the fact that the sizes of atoms of incorporated metals differ from these for matrix niobium, the lattice parameters of the matrix (Nb) change and additional stresses appear in it up to the lattice destruction. The parameters of the bcc lattice of solid solutions increase with an increase in concentrations of Pb, Cd, and Sn in connection with their atomic sizes more when compared with niobium. The change in the growth rate of the crystal lattice is caused by the change in the schematic of the arrangement of impurity atoms in the matrix niobium lattice for alloys with lead and cadmium. Based on the critical particle sizes of metals, the magnitudes of the surface tension at the crystal–melt boundary are evaluated. They are as follows, J/m2: 1.17–1.22 for Nb, 1.15 × 10–2 for Sn, 1.48 × 10–2 for Pb, and 0.142 for Cd. The fabrication of alloys of refractory niobium with tin, lead, and cadmium is an example of using the size effect when fabricating new materials.     

Si(100)衬底上CeO2薄膜的脉冲激光制备及性能研究

用CeO2陶瓷靶材,使用脉冲激光沉积(PLD)技术在Si(100)衬底上制备了CeO2薄膜.研究了衬底温度、沉积氧压对薄膜性能的影响,实验制备出了高度(111)取向的CeO2薄膜.使用X射线衍射(XRD)、反射式高能电子衍射(RHEED)对薄膜进行晶体结构的表征.结果表明:随着衬底温度的增加,薄膜中的残余宏观应力(拉应力)及微观应力逐渐减小,薄膜结晶质量不断提高,而沉积氧压对此影响较小.RHEED图像显示使用PLD方法在Si衬底上沉积的薄膜具备较高的结晶性及原子级平整的表面.使用原子力显微镜(AFM)对样品进行表面粗糙度分析,发现不同温度下生长的薄膜均具有光滑的表面,方均根粗糙度(RMS)均在0.4 nm以下.使用Keithley 4200半导体测试仪、椭偏仪对薄膜进行电性能及光学性能分析,发现衬底温度对薄膜的电学性能有显著影响,并且CeO2薄膜结晶状态与电学性能有直接的联系.     

HDDR三元NdFeB各向异性材料的制备

研究了HDDR三元NdFeB各向异性磁粉的制备工艺.发现脱氢速度对HDDR三元各向异性NdFeB的磁性能具有显著影响;缓慢的脱氢处理有助于材料获得高的各向异性.在最佳工艺条件下,可获得磁能积为84 kJ·m³的HDDR三元NdFeB各向异性粘结磁体.     

分子模板法制备纳米多孔SiO2薄膜

报道了用分子模板法制备纳米有序多孔SiO2薄膜。用扫描电子显微镜(SEM)观察改性前后薄膜的表面形貌，发现改性后薄膜孔洞大小均匀，排列有序，孔径在200nm左右。付立叶红外变换光谱(FTIR)研究表明，改性后薄膜内存在大量的一CH3键，增强了薄膜的憎水性，可以有效抑制孔洞塌缩。用椭圆偏振光测试仪测量并计算了薄膜的介电常数和膜厚，并且研究了热处理温度对二者的影响，发现当热处理温度为350℃时薄膜厚度约为400nm，此时介电常数有最低值1．66。     

电镀Ni—P非晶合金的研制

本文研究了在电沉积过程中阴极超电位与形成非晶态的关系。实验结果表明,在阴极极化曲线的平台处易产生非晶态。还讨论了电沉积条件对形成非晶态镀层的影响。在较高的镀液温度,低的pH值及适当的电流密度的条件下,镀液中H₃Po₃含量达到一定的比值,镀层易形成非晶态。镀液中H₃PO₃含量越高,镀层中的磷含量越高,当磷含量超过9%时形成非晶态,且镀层的耐蚀性随其磷含量的增加而增强。热处理温度对镀层的影响也做了检验。     

利用ROC技术制备TiNi形状记忆合金的研究

利用快速全向压制（ＲＯＣ）技术直接由钛、镍元素粉末制备了ＴｉＮｉ形状记忆合金。利用密度测试、显微组织观察、Ｘ射线衍射分析以及性能测试等手段对影响ＴｉＮｉ合金制备过程的主要影响因素进行了分析研究,并对制备的ＴｉＮｉ合金进行了热轧、冷轧等加工性能试验。利用ＲＯＣ技术可以得到反应充分、结构密实并具有良好性能的ＴｉＮｉ形状记忆合金。     

Fabrication and Characterization of Ni-SiC Nanocomposite Coatings on Al Substrates by Ball Impact Deposition Method

Micron-size Ni and SiC powder mixtures were used to prepare Ni-SiC nanocomposite coatings on an Al substrate by employing a high-energy ball milling technique. Ni:SiC weight ratio was varied over a wide range to explore the effect of the charge composition on the microstructure, composition, microhardness, and wear properties of the depositions. It was observed that the composition of the produced coating was correlated to the charge composition in a complex manner, which suggests that deposition rates for Ni and SiC particles significantly vary depending on the charge composition; SiC deposition rate was higher than that of Ni when Ni:SiC weight ratio was greater than 3:1. Diffusion of Al from the substrate into the Ni matrix provided evidence for the metallurgical bonding at the interface. Both microstructural and mechanical properties of the produced coatings were found to be crucially dependent on the charge composition. By increasing the SiC content in the charge from about 5 to 33 wt pct, the mechanical properties enhanced due to the dispersion strengthening effect of the incorporated SiC particles in the coatings and the crystallite size of the Ni matrix decreasing to the nanometer range. However, a further increase resulted in the formation of a coating with a poor degree of compaction. It was found that the composite coating with about 15 vol pct SiC, produced from the charge with Ni:SiC weight ratio of 2:1, showed a microhardness as high as 830 HV_0.05 along with excellent wear resistance. Despite the current sample size limitations for applying high-energy ball milling, the present findings demonstrate that the adopted technique holds good prospect for the synthesis of nanostructured metal matrix composite coatings with enhanced and tunable properties.

     

轧机油膜轴承最小油膜厚度的分析及应用

采用有限差分法联立求解雷诺方程膜厚方程及弹性变形方程,对油膜轴承的油膜厚度进行定量分析,得出不同工况下的轴承最小油膜厚度,为进一步完善油膜轴承的设计提供理论依据.     

Calculation of the Heat of Formation:Ternary Alloy System

A semi-empirical calculation of the heat of formation was applied to ternary system:La-Fe-Al,Fe-Ni-V and Cu-Pd-Si.The calculated values were compared with the experimental ones andthe coincidence was satisfactory.This method is helpful to predict the stabilities of ternary compounds andsolid solubility.     

工艺条件对电沉积CoPtW合金成分的影响

报道了以钨酸钠、硫酸钴和二亚硝酸二胺铂为主盐、以柠檬酸盐为络合剂电沉积钴铂钨合金的工艺过程。研究了镀液中钨盐浓度、络合剂浓度、电流密度、镀液温度等沉积条件对钴铂钨合金成份的影响。结果表明，在实验条件下，镀液中钨盐含量的增加、电流密度的增大和镀液温度的升高都会引起合金镀层中的钨含量增大。络合剂用量的增加使合金镀层中的钨含量下降，而使钴和铂的含量增加。     

激光熔化沉积Cu-Fe合金的液相分离组织及力学性能研究

难混溶合金由于亚稳难混溶间隙的存在,在制备过程中极易产生偏析甚至分层现象,严重影响材料的使用性能。激光熔化沉积小熔池无宏观偏析的特点,为制备均质难混溶合金提供了潜在途径。本文选取典型难混溶Cu-Fe合金作为研究对象,采用激光熔化沉积制备了薄壁状Cu35Fe65难混溶合金,研究了合金的物相组成、微观组织形貌与力学性能。结果表明：合金由体心立方（bcc）结构的α-Fe相与面心立方（fcc）结构的Cu相组成;合金呈现典型的液相分离形貌,由网络状Cu相与块状α-Fe相构成,α-Fe相平均直径为8 μm;合金屈服强度为397 MPa,抗拉强度为484 MPa,延伸率为16.5%,断裂方式主要为韧性断裂;合金的导电率为19% IACS,较高的α-Fe相体积分数可能是影响合金电阻率的主要因素。本研究表明,激光熔化沉积技术有望成为高性能难混溶合金的有效制备方式。     

Fabrication of Cerium Oxide Nanoparticles by Solution Combustion Synthesis and Their Cytotoxicity Evaluation

The diverse abilities such as the antioxidant effect of cerium oxide nanoparticles (CeO₂-NPs) have encouraged researchers to pursue CeO₂-NPs as a therapeutic agent to treat a number of diseases, including cancer and diabetes. The synthesis method of CeO₂-NPs affected on its abilities. In this study, nanosize ceria powders were synthesized by combustion of aqueous containing corresponding cerium nitrate, ammonium nitrate, and glycine redox mixtures. Solution combustion synthesis is a fast and cost-efficient process with high purity product. The crystallite structures were characterized by various methods, including X-ray diffraction technique, high-resolution scanning electron microscopy, transmission electron microscopy, and UV–vis spectroscopy technique. The combustion was flaming and yields voluminous oxides with nano size (20–30 nm). In addition, no diffraction patterns that are characteristic of impurities were observed, indicating the purity of the CeO₂-NPs. In vitro cytotoxicity studies on L929 cells, a non-toxic effect in all concentration (up to 1000 μg/mL) was indicated and it can be believed that this nanoparticle will have viable applications in different medical fields.     

Fabrication of Ti-6Al-4V Scaffolds by Direct Metal Deposition

Direct metal deposition (DMD) is a rapid laser-aided deposition method that can be used to manufacture near-net-shape components from their computer aided design (CAD) files. The method can be used to produce fully dense or porous metallic parts. The Ti-6Al-4V alloy is widely used as an implantable material mainly in the application of orthopedic prostheses because of its high strength, low elastic modulus, excellent corrosion resistance, and good biocompatibility. In the present study, Ti-6Al-4V scaffold has been fabricated by DMD technology for patient specific bone tissue engineering. Good geometry control and surface finish have been achieved. The structure and properties of the scaffolds were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tension test. The microstructures of laser-deposited Ti-6Al-4V scaffolds are fine Widmanstätten in nature. The tensile and yield strengths of the as-deposited Ti-6Al-4V were 1163 ± 22 and 1105 ± 19 MPa, respectively, which are quite higher than the ASTM limits (896 and 827 MPa) for Ti-6Al-4V implants. However, the ductility of the as-deposited sample was very low (～4 pct), which is well below the ASTM limit (10 pct). After an additional heat treatment (sample annealed at 950 °C followed by furnace cooling), both strength (UTS ～ 1045 ± 16, and YS ～ 959 ± 12 MPa) and ductility (～10.5 ± 1 pct) become higher than ASTM limits for medical implants.     

辉光放电原子发射光谱法测定钢铁表面纳米尺度薄膜厚度的重复性和再现性

以辉光放电原子发射光谱法测定钢铁表面纳米尺度薄膜的厚度为例进行了膜厚测定的多家实验室共同试验。对共同试验的结果进行了计算,得到相应的重复性和再现性数据,得出膜厚与重复性之间的关系为:lgr=0.018 3+0.459 6 lgm;膜厚与再现性之间的关系为:lgR=0.140 9+0.485 lgm。并对共同试验中出现的准确度问题——薄膜的密度和最小光源稳定时间进行了讨论。     

沉淀法制备纳米粉体及其形貌控制

根据其应用来控制纳米粉末的形貌是制备纳米粉体十分关键的技术特征，本文讨论了沉淀法制备纳米粉末的特点及其形貌控制的措施，并对形貌控制的机理进行了探讨。     

磁控溅射TiNiLaZr合金膜的制备与电化学性能研究

前言Ti合金具有较好的储氢能力和抗腐蚀性，已得到许多储氢工作者的关注［’－‘］，并被认为是未来最具竞争潜力的储氢合金系列。在Ti中加入微量La，可明显改善其活化性能”‘。虽然已有研究者利用离子溅射制备出TINi合金膜［‘］，但将加入微量La、Zr的TINi合金制成非晶膜还较少有报道。本文在制备TINILaZr非晶膜及测定合金的电化学性能方面做了一些探索性工作。1合金膜的制备1．l合全膜的制备方法利用430H磁控溅射仪制备合金膜。将纯度为99．9％的Ni块、98％的La块及99．9％的Zr块按一定比例拼在纯度为99．9％的Ti靶上，制成复…     

SnO2透明电热膜成膜研究

研究了在化学喷射法制备ＳｎＯ２透明电热膜中，掺杂浓度、反应温度、退火工艺及喷射参数对电热膜光电性能的影响。结果表明在４００～６００℃、Ｓｂ３＋掺杂浓度在０１％～０４％之间，可获得透光率＞８５％，面电阻１００～１５０Ω的ＳｎＯ２透明电热膜。     

The Structure Formation and Hardness of High-Entropy Alloy Coatings Obtained by Electrospark Deposition

Powder Metallurgy and Metal Ceramics - This paper examines the use of high-entropy alloys (HEAs) as materials for electrospark deposition (ESD). This method is known to produce high-quality...     

钛合金表面焊接碳化钨硬质合金层厚度的有限元模拟设计

在Ti6Al4V合金表面焊接上适当厚度的碳化钨硬质合金,是提高其表面强度和耐磨性的一种行之有效的方法.作为一种整体结构件,在实际应用中碳化钨硬质合金层的厚度对部件的内应力分布以及尺寸稳定性有着重要的影响.因此从实际工况出发,利用先进的纳米显微力学探针测量了材料的弹性模量,然后采用ANSYS有限元软件,对钛合金表面焊接碳化钨硬质合金层,在受压情况下的应力分布和整体变形情况进行分析,以此对碳化钨合金层的厚度进行模拟,结果表明,当碳化钨合金层厚度在0.25～0.5 mm时,最大等效应力发生在钛合金和碳化钨合金层之间,容易引起界面处裂纹的产生;合适的碳化钨硬质合金层厚度范围应在0.5～1.5 mm之间,最佳的厚度应该是1 mm左右.