激光技术应用于材料表面缺陷自动测量的研究

利用激光光热辐射技术对测量材料缺陷的原理、实验技术进行了研究,设计了硬件与软件,实现了测量自动化,并对复合材料样品进行了测量。

基于红外热成像技术的材料表面缺陷识别研究

针对当前材料表面缺陷识别方法存在的误差大,实时性差等不足,为了提高材料表面缺陷识别精度,提出了基于红外热成像技术的材料表面缺陷识别方法。首先分析材料表面缺陷识别的原理,找到不同方法的局限性,然后计算材料表面的温度,判断材料表面是否完整,并采集材料表面缺陷识别的红外热图像,最后采用全局阈值分割对材料表面缺陷进行分割和边缘检测,通过获取变化过程中局部极大值的位置、对应的模位置、对应的幅角位置描绘出缺陷边缘的集合点,确定红外热图像内的缺陷位置,实现材料表面缺陷识别。仿真实验对比结果表明,本方法的材料表面缺陷识别准确率为97.5%,而且材料表面缺陷识别时间较短,平均值为2.5 s,具有良好的材料表面缺陷识别实时性。

热镀锌复相钢研发机理及材料表面缺陷控制研究

为了提升钢铁的美观度和使用寿命,执行热镀锌复相钢工艺,并对工艺流程进行严格控制,最大程度的降低表面缺陷产生的可能性。对热镀锌复相钢的研发机理进行分析,并分析材料在研发过程中不同类型表面缺陷形成的过程和影响因素。针对不同类型的表面缺陷,制定相应的控制方案。从实践结果来看,应用材料表面缺陷控制方法后,热镀锌复相钢材料表面的缺陷面积降低了68.1%。

苏州纳米所在薄膜光伏界面材料方面取得研究进展

在有机太阳能电池中常用的溶液法界面材料为金属氧化物纳米材料和聚合物／小分子类有机界面层材料。这两类界面材料在实际应用中都存在着优缺点，比如金属氧化物纳米材料表面缺陷多，容易聚集；有机类界面材料厚度控制严格，且最有优厚度在10nm以内，不适合于印刷法制备。

碳纤维布加固混凝土与砌体结构施工技术比较与分析

本文通过在混凝土基材与砌体基材上粘贴碳纤维布时，因基材种类、表面缺陷、强度等方面的差异，进行施工技术比较与分析。并通过实例对砌体结构粘贴碳纤维布的特殊施工工艺及其良好的控制效果做了介绍和分析。

异形工件专用荧光磁粉探伤机的研制使用

众所周知，磁粉探伤作为铁磁性材料表面缺陷最有力的检测手段在检测工作中得到了十分广泛的应用。在锅炉、压力容器、压力管道及石化管件及一些大型构件的局部检测中一般采用磁轭法或旋转磁场法探伤，但对一些形状复杂或工件有一定批量的情况这种方法就显得效率不高和灵敏度不够，存在局部漏检现象。在无损检测工作中，经常会遇到一些特殊工件的无损探伤难以有效进行。比如对石化管件（如三通、四通等）、

Interface microstructure and mechanical properties of selective laser melted multilayer functionally graded materials

Functionally graded material(FGM)can tailor properties of components such as wear resistance,corrosion resistance,and functionality to enhance the overall performance.The selective laser melting(SLM)additive manufacturing highlights the capability in manufacturing FGMs with a high geometrical complexity and manufacture flexibility.In this work,the 316L/CuSn10/18Ni300/CoCr four-type materials FGMs were fabricated using SLM.The microstructure and properties of the FGMs were investigated to reveal the effects of SLM processing parameters on the defects.A large number of microcracks were found at the 316L/CuSn10 interface,which initiated from the fusion boundary of 316L region and extended along the building direction.The elastic modulus and nano-hardness in the 18Ni300/CoCr fusion zone decreased significantly,less than those in the 18Ni300 region or the CoCr region.The iron and copper elements were well diffused in the 316L/CuSn10 fusion zone,while elements in the CuSn10/18Ni300 and the 18Ni300/CoCr fusion zones showed significantly gradient transitions.Compared with other regions,the width of the CuSn10/18Ni300 interface and the CuSn10 region expand significantly.The mechanisms of materials fusion and crack generation at the 316L/CuSn10 interface were discussed.In addition,FGM structures without macro-crack were built by only altering the deposition subsequence of 316L and CuSn10,which provides a guide for the additive manufacturing of FGM structures.

Hierarchical AgAu alloy nanostructures for highly efficient electrocatalytic ethanol oxidation

The ethanol oxidation reaction is a significant anodic reaction for direct alcohol fuel cells.The most commonly used catalysts for this reaction are Pt‐based materials;however,Pt‐based electrocatalysts cause carbon monoxide poisoning with intermediates before the complete transformation of alcohol to CO_(2).Herein,we present hierarchical AgAu bimetallic nanoarchitectures for ethanol electrooxidation,which were fabricated via a partial galvanic reduction reaction between Ag and HAuCl_(4).The ethanol electrooxidation performance of the optimal AgAu nanohybrid was increased to 1834 mA mg^(‒1),which is almost 10 times higher than that of the pristine Au catalyst(190 mA mg^(‒1))in alkaline solutions.This was achieved by introducing Ag into the Au catalyst and controlling the time of the replacement reaction.The heterostructure also presents a higher current density than that of commercial Pt/C(1574 mA mg^(‒1)).Density functional theory calculations revealed that the enhanced activity and stability may stem from unavoidable defects on the surface of the integrated AgAu nanoarchitectures.Ethanol oxidation reactions over these defects are more energetically favorable,which facilitates the oxidative removal of carbonaceous poison and boosts the combination with radicals on adjacent Au active sites.

Analysis and Control of Surface Delamination Defects During Milling of Orthogonal Aramid Fiber‑Reinforced Composites Laminates

The aramid fiber-reinforced composites(AFRC)can increase the durability of corresponding applications such as aerospace,automobile and other large structural parts,due to the improvement in hardness,heat build-up,wear properties and green environmental protection.However,because of its complex multiphase structure and unique heterogeneity and anisotropy,the poor compression fatigue resistance and the incident surface fibrillation are inevitable.To improve the assembly precision of AFRC,mechanical processing is necessary to meet the dimensional accuracy.This paper focuses on the influence of contour milling parameters on delamination defects during milling of AFRC laminates.A series of milling experiments are conducted and two different kinds of delamination defects including tearing delamination and uncut-off delamination are investigated.A computing method and model based on brittle fracture for the two different types of delamination are established.The results can be used for explaining the mechanism and regularity of delamination defects.The control strategy of delamination defects and evaluation method of finished surface integrity are further discussed.The results are meaningful to optimize cutting parameters,and provide a clear understanding of surface defects control.

Effect of coating material and lubricant on forming force and surface defects in wire drawing process

A pilot wire drawing machine as well as wire end-pointing roller was developed. Using these machines, a wire drawing test for four different coating materials and two different lubricants was performed as the reduction ratio increased from 10% to 30%. Materials used for a substrate in this study are plain carbon steel （AIS11045） and ultra low carbon bainite steel. To compute the friction coefficient between the coating layer of wire and the surface of die lbr a specific lubricant, a series of finite element analyses were carried out. SEM observations were also conducted to investigate the surface defects of wire deformed. Results show that the behavior of drawing force varies with the lubricant-type at the initial stage of drawing. The powder-typed lubricant with a large particle causes the retardation of lull lubrication on the entire contact surface and the local delamination of coating layer on the wire surface. As the flow stress of a substrate increases, the delamination becomes severe.

Raman spectroscopy investigation of structural and textural change in C/C composites during braking

The microstructure and texture of C/C composites with a resin-derived carbon, a rough laminar （RL） pyrocarbon and a smooth laminar pyrocarbon, before and after braking tests, were investigated by Raman spectroscopy. The full width at half maximum （FWHM） of the D-band indicates the amount of defects in the in-plane lattice, while the G-to-D band intensity （peak area） ratios （lC/ID） is used to evaluate the degree of graphitization. The results show that the FWHM of D-band of sample with RL pyrocarbon changes greatly from 36 cm-1 to 168 cm 1 after braking tests, which indicates that a large number of lattice defects are produced on its wear surface. However, the graphitization degree of resin-derived carbon sample rises significantly, because the IC/1D increases from 0.427 to 0.928. Braking tests under normal loading conditions, involving high temperature and high pressure, produce a lot of lattice defects on the wear surface, and induce the graphitization of the surface. Sample with RL pyrocarbon having a low hardness is easy to deform, and has the most lattice defects on the wear surface after braking. While raw materials with resin-derived carbon have the lowest graphitization degree which rises greatly during braking.

螺旋弹簧断裂分析及预防措施

60Si2CrVAT合金弹簧钢具有优良的弹性,在很多弹簧产品中得到了应用,然而60Si2CrVAT弹簧钢在实际使用过程中经常早期断裂失效。一些研究人员认为内部缺陷是造成早期失效的主要原因,主要包括由材料的石墨化、异常组织、非金属夹杂物等。此外,材料表面缺陷,如脱碳和表面凹坑、

Synthesis of TiO_2 photocatalysts with abundant surface defects using a TiO_2@NaCl precursor

TiO2 nanoparticles have been synthesized by using a TiO2@NaCl core-shell structure as the precursor. The surface defects were well preserved by the NaCl shell, and therefore high oxygen adsorption capacity was observed. After the NaC1 shell was removed, the resulting pure TiO2 nanoparticles were of anatase phase and uniform size of around 20-24 nm. The presence of an abundance of surface defects contributes to the high photocatalytic activity of the synthesized materials, and the TiO： mate- rials obtained from the TiO2@NaCl precursor can be used as efficient photocatalysts for degradation of rhodamine B under UV light irradiation.

Understanding the defect chemistry of oxide nanoparticles for creating new functionalities:A critical review

This work presents a critical review on the studies of defect chemistry of oxide nanoparticles for creating new functionalities pertinent to energy applications including dilute-magnetic semiconductors,giant-dielectrics,or white light generation.Emphasis is placed on the relationships between the internal structure and defective surfaces of oxide nanoparticles and their synergy in tailoring the materials properties.This review is arranged in a sequence:(1) structural fundamentals of bulk oxides,using TiO2 as a model simple oxide to highlight the importance of polymorphs in tuning the electronic structures;(2) structural features of simple oxide nanoparticles distinct from the bulk,which show that nanoparticles can be considered as a special solid under the compression as originated from the surface defect dipole-dipole interactions;and(3) new functions achieved through extending the defect chemistry concept to the assembled architectures or multi-component oxide nanoparticles,in which defect surfaces enable the localized electrons or intermediate levels to produce giant dielectric performance or tunable light generation.It is concluded that understandings of defect chemistry provide diverse possibilities to manipulate electrons in oxide nanoparticles for functionalities in energy-relevant applications.

Inorganic material passivation of defects toward efficient perovskite solar cells

Surface passivation with organic materials is one of the most effective and popular strategies to improve the stability and efficiency of perovskite solar cells(PSCs). However, the secondary bonding formed between organic molecules and perovskite layers is still not strong enough to protect the perovskite absorber from degradation initialized by oxygen and water attacking at defects. Recently, passivation with inorganic materials has gradually been favored by researchers due to the effectiveness of chemical and mechanical passivation. Lead-containing substances, alkali metal halides, transition elements, oxides,hydrophobic substances, etc. have already been applied to the surface and interfacial passivation of PSCs.These inorganic substances mainly manipulate the nucleation and crystallization process of perovskite absorbers by chemically passivating defects along grain boundaries and surface or forming a mechanically protective layer simultaneously to prevent the penetration of moisture and oxygen, thereby improving the stability and efficiency of the PSCs. Herein, we mainly summarize inorganic passivating materials and their individual passivation principles and methods. Finally, this review offers a personal perspective for future research trends in the development of passivation strategies through inorganic materials.