铁基渗硼强化粉末冶金材料的性能及渗层生长动力学研究

目的 通过固体粉末渗硼法直接烧结铁基粉末冶金材料，制备具有渗硼层的试样。方法 采用固体渗硼工艺对铁基粉末冶金材料在1123、1223、1323 K温度下渗硼处理3、5、7、10 h，采用光学显微镜及扫描电镜（SEM）观察了渗硼层的形貌，测定了渗硼层的厚度。用X射线衍射仪分析了渗硼层的物相组成，用摩擦磨损试验评估渗硼层的耐磨性，采用Rockwell-C粘附性试验评估渗硼层与基体的粘合强度质量。对渗层的生长动力学曲线进行拟合，得出渗层动力学曲线和厚度等值线图。结果 试样的渗硼层厚度为35~ 183 μm，1323 K条件下获得双相渗硼层（Fe2B+FeB），1123 K及1223 K条件下获得单相渗硼层Fe2B。试样在1223 K温度下渗硼处理5 h获得的渗硼层的耐磨性最佳，其粘合强度质量根据规范通过HF3等级认可。该试验中B元素的扩散激活能为164 kJ/mol。结论 烧结温度和渗硼时间与渗层厚度关系密切，渗硼时间与渗层厚度的关系呈现出抛物线关系。厚度值的平方与渗硼时间符合阿瑞纽斯（Arrhenius）公式呈线性关系。渗硼层的显微硬度显著高于基体硬度，随时间的增加，渗层中出现较多的孔洞与疏松，渗硼层形状由明显的梳齿状逐渐变成不太明显的梳齿状，此情况在高温下更加明显。     

从渗硼层的结构和性能探讨渗硼的机制

用相同的渗硼工艺对45钢、T10钢和CrWMn钢进行了渗硼处理，观察其渗硼层的厚度和形态；对不同材料的渗硼试样进行淬火，对比其耐磨性能，探讨渗硼的机制，分析造成不同材料渗硼层的厚度、硬度及耐磨性不同的原因。     

硬质合金渗硼层组织及厚度的研究

本文以WC-Co硬质合金为渗硼研究对象,研究开发出一种感应加热密闭容器气-固渗硼工艺方法 ,借助于金相显微镜对渗硼层厚度实现了直接观察,应用SEM、EDS能谱、XRD、场发射电镜等对合金的组织进行了分析。实验结果表明:渗硼层厚度可达0.1～0.5 mm,渗硼层Co粘结相中弥散分布羽毛状W-C-Co-B析出相;感应加热、密闭容器中气相的作用和渗硼剂中的稀土促进了渗硼过程的进行;硬质合金Co含量、渗硼温度、渗硼时间增加有利于渗硼层厚度增加;应用数据拟合得到了YG11合金渗硼层厚度与渗硼温度、渗硼时间关系表达式。     

Q345B钢膏剂渗硼工艺的试验研究

利用正交试验法研究了膏剂厚度、渗硼温度和时间对Q345B钢渗硼层厚度的影响.结果表明:在给定的试验条件下,各因素对渗硼层厚度的影响顺序是膏剂厚度、渗硼时间、渗硼温度,并确定了最佳膏剂渗硼工艺方案为膏剂厚度6 mm,渗硼温度900℃,渗硼时间7h.     

45钢渗硼工艺的正交分析研究

研究了渗硼温度、供硼剂种类、活化剂种类及其含量对渗硼层厚度和质量的影响，并对硼砂型渗硼剂中加入硅铁作为还原剂对渗硼效果的影响也进行了研究。结果表明：温度与供硼剂种类是45钢渗硼的主要影响因索；45钢渗硼的最优工艺方案为：供硼剂选用B4C 稀土，活化剂为Na3AlF6，活化剂含量为20％～30％，温度为950℃；以硼砂为供硼剂的渗硼剂中加入硅铁粉能提高渗硼层的厚度及渗硼质量。     

20钢固体粉末法渗硼和硼钒共渗的渗层研究

采用光学显微镜、扫描电镜和电子探针等检测手段，分析了20钢固体法渗硼和硼钒共渗的渗层组织结构、成分特点及其硬度分布。结果表明，硼钒共渗层厚度大于单一渗硼层，且渗层更加连续致密，其渗层主要由Fe2B、V2C和VB相组成，硼钒共渗层硬度比单一渗硼有所提高，硬度梯度较小。     

20钢包埋粉末渗硼层的组织及耐蚀性能研究

研究了20钢在不同渗硼温度和不同渗硼时间下对渗硼层组织和性能的影响。用金相显微镜和扫描电镜观察了渗硼层的形貌,测定了渗硼层的厚度;用维氏硬度计测定了渗硼层的硬度;用纳米压痕仪测定了渗硼层不同深度的硬度;评定了渗硼层与基体的结合力;采用X射线衍射仪分析了渗硼层的物相组成;在不同溶液中进行了渗硼层耐蚀性试验。结果表明:渗硼层厚度均匀,呈齿状结构,与基体结合牢固,渗硼层主要由Fe_2B组成。在860℃下保温不同时间,渗硼层的厚度随时间的增长而增大;在不同温度下保温5h时,渗硼层的厚度随温度的升高而逐渐增大。渗硼层表层硬度稍低,然后升高达到最大值,在渗层与过渡区的交界处急剧下降。除HNO_3外,渗硼处理后的试样在HCl、H_2SO_4、NaCl和NaOH溶液中的耐蚀性均比未渗硼的试样好。     

Q345B钢膏剂感应渗硼工艺研究

通过试验探究通过感应渗硼方式对Q345B进行快速渗硼.利用单因素方法分别确定超音频感应渗硼时间和功率对渗硼层厚度的影响,给出了渗硼层显微组织分析及硬度分析.结果表明:在给定的试验条件下,最佳工艺方案为感应加热功率4377.5 W(振荡电流40 A),有效感应加热时间9min,渗硼层厚度最大达到33 μm,渗硼层显微硬度为1400～2000 HV.     

TC4钛合金表面氧化锆催渗渗硼工艺的优化

以渗层厚度和表面硬度为评定依据,采用正交试验对TC4钛合金表面氧化锆催渗渗硼工艺进行了优化,其中渗硼温度影响最大,其次为渗硼时间和ZrO2含量,B4C含量影响最小,最优工艺为:渗硼温度1 050℃,渗硼时间25h,渗硼剂配比(质量分数):B4C 20%,ZrO24%,SiC 76%。利用X射线衍射仪和光学显微镜对渗层的物相组成和厚度进行分析,结果表明:渗层表面主要由TiB2、TiB、TiB12、TiC、TiN组成,渗层厚度为46.67μm。与基础渗硼剂所得渗层相比,渗硼层厚度、渗层硬度、界面结合力和耐磨性都有所提高。     

用MATLAB研微波渗硼扩散问题

用MATLAB的偏微分方程（PDE）工具箱求解钢在微波渗硼过程中的扩散偏微分方程，计算了渗硼层厚度。仿真结果与实测数据相比表明，用MATLAB的PDE工具箱求解微波渗硼过程中的扩散偏微分方程具有较高的精度，计算出的渗硼层厚度与实测的相比，计算误差小于4．05％。     

An Investigation of Surface Transformations of Nickel Highly Porous Cellular Material with an Applied Alumina Layer during Its Synthesis

For the development of a composite of nickel highly porous permeable cellular material with an applied secondary layer of alumina, transformation of the surface of the highly porous permeable cellular material is investigated at the stages of electrochemical synthesis and stages of alumina application on its surface. Etching of foamed-polyurethane bondings with 20% potassium hydroxide solution is accompanied by destruction of their surface and the formation of defective areas in the form of hillocks, hollows, and other imperfections acting as tin-hydroxide crystallization nuclei. Application of tin chloride with its subsequent hydrolysis leads to the formation of hemispherical tin-hydroxide grains with a mean size of about 80 nm uniformly distributed over the surface. The optimum values of temperature (50°C), solution pH (9–10), and electroless-nickel-plating duration (20–30 min), providing the formation of a conductive sublayer of chemically reduced nickel, are established. Nickel electroplating for 30 to 35 h at a current density of 0.1 A/dm2 yields high uniformity of a metal coating of foamed-polyurethane bondings across the thickness both in the bulk and at the outer periphery of a sample of 30 μm. A composite of nickel highly porous permeable cellular material with an applied alumina secondary layer is synthesized. The latter shows a high degree of uniformity and uniform thickness over the whole surface of bondings of the obtained composite.     

Ultrasonic characterization of porous silicon using a genetic algorithm to solve the inverse problem

This paper presents a method for ultrasonic characterization of porous silicon in which a genetic algorithm based optimization is used to solve the inverse problem. A one-dimensional model describing wave propagation through a water immersed sample is used in order to compute transmission spectra. Then, a water immersion wide bandwidth measurement is performed using an insertion/substitution method and the spectrum of signals transmitted through the sample is calculated using Fast Fourier Transform. In order to obtain parameters such as thickness, longitudinal wave velocity or density, a genetic algorithm based optimization is used.A validation of the method is performed using aluminium plates with two different thicknesses as references: a good agreement on acoustical parameters can be observed, even in the case where ultrasonic signals overlap.Finally, two samples, i.e. a bulk silicon wafer and a porous silicon layer etched on silicon wafer, are evaluated. A good agreement between retrieved values and theoretical ones is observed. Hypothesis to explain slight discrepancies is proposed.     

不锈钢纤维多孔材料的吸声性能

采用不锈钢纤维为原料制备不同孔隙性能的纤维多孔材料，采用驻波管法检测该纤维多孔材料的空气声吸收系数，研究材料的孔隙度、纤维直径以及材料厚度等参数对吸声性能的影响，同时研究在材料背后设置空气层以及空气层厚度对材料吸声性能的影响关系。结果表明：实验采用的不锈钢纤维多孔材料具有较好的吸声性能，材料的孔隙度越高、厚度越大、纤维越细，材料的吸声性能越好，在材料背后设置空气层可显著改善其低频吸声性能，材料背后的空气层厚度越大，材料的低频吸声性能越好。     

固体硼氮共渗提高渗层的耐蚀性和抗高温氧化性能

用尿素为供氮剂进行固体硼氮共渗,研究了硼氮共渗层的耐蚀和抗高温氧化性能,并与渗硼层作了比较。结果表明,因先期渗入的氮原子在渗硼温度所起的有益作用,致使硼氮共渗层的耐蚀和抗高温氧化性能均优于渗硼层。     

多孔化高熵合金改善Al-Si合金/钢体系润湿铺展性能机理

借助电极感应熔化气雾化法,制备了 FeCoNiCrMn高熵合金粉末;通过真空烧结技术,在钢表面制备了具有不同孔隙率和孔径的多孔高熵合金涂层. 研究了不同烧结工艺对多孔涂层孔隙率、孔径以及过渡层厚度的影响. 开展了Al-12Si合金在多孔高熵涂层钢表面的原位润湿铺展试验,探讨了多孔高熵合金涂层对表观接触角和铺展行为的影响规律,深入分析了多孔高熵结构内反应产物的显微组织和相组成. 结果表明,随着烧结温度的升高和保温时间的延长,多孔高熵合金涂层的过渡层厚度逐渐升高,孔隙率及平均孔径逐渐减少. 液态Al-12Si合金液滴在多孔涂层中微通道增强的毛细力作用下,迅速浸润到多孔结构中,并实现了材料表面的完全润湿. 在高熵合金的迟滞扩散效应与高熵效应共同作用下, 界面反应层中金属间化合物的形成受到显著阻碍,界面相结构由富Cr的FCC、富AlFe的BCC以及富AlNi的B2 + 富Al的BCC共晶状结构组成.     

Microstructural and Optical Properties of Porous Alumina Elaborated on Glass Substrate

A transparent porous anodized aluminum oxide (AAO) nanostructure was formed on a glass substrate using the anodization of a highly pure evaporated aluminum layer. A parametric study was carried out in order to achieve a fine control of the microstructural and optical properties of the elaborated films. The microstructural and surface morphologies of the porous alumina films were characterized by x-ray diffraction and atomic force microscopy. Pore diameter, inter-pore separation, and the porous structure as a function of anodization conditions were investigated. It was then found that the pores density decreases with increasing the anodization time. Regular cylindrical porous AAO films with a flat bottom structure were formed by chemical etching and anodization. A high transmittance in the 300-900 nm range is reported, indicating a fulfilled growth of the transparent sample (alumina) from the aluminum metal. The data showed typical interference oscillations as a result of the transparent characteristics of the film throughout the visible spectral range. The thickness and the optical constants (n and k) of the porous anodic alumina films, as a function of anodizing time, were obtained using spectroscopic ellipsometry in the ultraviolet-visible-near infrared (UV-vis-NIR) regions.     

电沉积铁氰化镍测定多孔膜电极的电活性面积

采用电化学方法测定三维多孔膜电极的电活性有效表面积、活性体积和表面覆盖度。以三维多孔电极或沉积有过渡金属铁氰化镍半导体薄膜的三维多孔膜电极为工作电极,分别在含铁氰化钾和不含铁氰化钾的碱金属溶液中测定不同扫描速度下的循环伏安曲线,利用膜电极在不同溶液体系中氧化/还原反应的可逆特性测定其电活性有效表面积和覆盖度;同时结合计时库仑法获得三维多孔膜电极内膜的活性体积和平均膜厚。结果表明:该方法具有电化学反应响应快速、灵敏且精确度高的优点,操作简单且快捷方便,可靠性好。     

Effect of Electrolytic Solution Concentrations on Surface Hydrophilicity of Micro-Arc Oxidation Ceramic Film Based on Ti6Al4V Titanium Alloy

在不同电解液浓度的钙盐和磷酸盐混合体系中对Ti6Al4V合金进行微弧氧化(MAO)以改善其微观结构和亲水性能。利用扫描电镜、X射线衍射仪、测厚仪以及电化学工作站等对生成膜层的显微结构、物相组成、厚度以及亲水性能进行研究。结果表明:所制备的微弧氧化膜表面为粗糙多孔结构,含锐钛矿、金红石以及少量羟基磷灰石。随磷酸二氢钾浓度升高,羟基磷灰石相增多;微弧氧化膜厚度增大到一定值后不再发生变化;微弧氧化致密层与疏松层比例发生变化,增厚的疏松层表面多孔,且有较多含Ca、P的羟基磷灰石相,陶瓷膜的亲水性能提高,使得微弧氧化陶瓷膜的生物相容性得到提高。     

烧结工艺对粉末烧结多孔材料微观结构与力学性能影响

本文进行了烧结气氛和烧结温度对支撑体孔径、透过性能影响的研究。环拉实验结果表明,氢气烧结样品的抗拉强度87.56MPa,氢气+氯化铵活化烧结样品115.20MPa,强度提高了30%。通过烧结温度对支撑体力学性能影响的研究,得到了支撑体致密度和力学性能之间的关系,可实现通过测试多孔材料的密度来预测多孔材料的强度。     

Nondestructive evaluation of transparent sheets using a full-field digital gradient sensor

A full-field, non-contact, optical inspection tool for transparent materials is demonstrated. The technique is sensitive to refractive index and thickness variations caused by inhomogeneities and defects in an otherwise uniform sheet stock. The technique utilizes a 2D digital image correlation method to visualize and quantify angular deflections of light rays in two orthogonal directions to assess the uniformity. The principle of the method and its feasibility is demonstrated by visualizing the heat affected zone in a uniform borosilicate sheet sample.