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Characterization,Removal and Evaluation of oxide film in the Diffusion Bonding of Zr_(55)Cu_(30)Ni_5Al_(10) Bulk Metallic Glass

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Journal of Materials Science & Technology 2014年第7期30卷 722-730页

作者： Haiyan Chen Jian Cao Xiaoguo Song Jiakun Liu Jicai Feng State Key Lab of Advanced Welding and Joining Harbin Institute of Technology School of Materials Science and Engineering Harbin Institute of Technology at Weihai

The composition of oxide film of ZrssCu3oNi5Al10 bulk metallic glass was identified by X-ray photoelectron spectroscopy. In addition, the relatively sound joints of bulk metallic glass without macroscopic deformation were obtained by removing the oxide film before diffusion bonding. The joint interfaces were observed by scanning electron microscopy and atomic force microscopy. The hardness of joints near the interface was higher than that far away from the interface, which is attributed to the difference of structural relaxation. According to the result of micro-focused X-ray diffractometry and transmission electron microscopy, the joints retained the amorphous structure when the holding time is less than 20 min. The surface area fraction of oxide film on the interface of joints was detected by ultrasonic inspection. Moreover, the surface area fraction of oxide film is in excellent agreement with the theoretical value calculated by shear strength. The result indicated that surface oxide film is the dominant barrier on the diffusion bonding of bulk metallic glass rather than low atomic diffusion coefficient.

关键词： Bulk metallie glass Diffusion Surface Diffusion bonding oxide film

Effect of oxide film on nanoscale mechanical removal of pure iron

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Friction 2018年第3期6卷 307-315页

作者： Jinwei LIU Liang JIANG Changbang DENG Wenhao DU Linmao QIAN Tribology Research Institute State Key Laboratory of Traction Power Southwest Jiaotong University Institute of Machinery Manufacturing Technology China Academy of Engineering Physics

In this paper, the properties of an oxide film formed on a pure iron surface after being polished with an H2O-based acidic slurry were investigated using an atomic force microscope （AFM）, Auger electron spectroscopy （AES）, and angle-resolved X-ray photoelectron spectroscopy （AR-XPS） to partly reveal the material removal mechanism of pure iron during chemical mechanical polishing （CMP）. The AFM results show that, when rubbed against a cone-shaped diamond tip in vacuum, the material removal depth of the polished pure iron first slowly increases to 0.45 nm with a relatively small slope of 0.11 nm/μN as the applied load increases from 0 to 4 μN, and then rapidly increases with a large slope of 1.98 nm/μN when the applied load further increases to 10 μN. In combination with the AES and AR-XPS results, a layered oxide film with approximately 2 nm thickness （roughly estimated from the sputtering rate） is formed on the pure iron surface. Moreover, the film can be simply divided into two layers, namely. an outer layer and an inner layer. The outer layer primarily consists of FeOOH （most likely α-FeOOH） and possibly Fe2O3 with a film thickness ranging from 0.36 to 0.48 nm （close to the 0.45 nm material removal depth at the 4 μN turning point）, while the inner layer primarily consists of Fe304. The mechanical strength of the outer layer is much higher than that of the inner layer. Moreover, the mechanical strength of the inner layer is quite close to that of the pure iron substrate. However, when a real CMP process is applied to pure iron, pure mechanical wear by silica particles generates almost no material removal due to the extremely high mechanical strength of the oxide film. This indicates that other mechanisms, such as in-situ chemical corrosion-enhanced mechanical wear, dominate the CMP process.

关键词： oxide film nanoscale mechanical removal pure iron chemical mechanical polishing

Thermomechanical coupling effect on characteristics of oxide film during ultrasonic vibration-assisted ELID grinding ZTA ceramics

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Chinese Journal of Aeronautics 2021年第6期34卷 125-140页

作者： Fan CHEN Guangxi LI Bo ZHAO Wenbo BIE School of Electrical and Mechanical Engineering Pingdingshan UniversityPingdingshan 467000China School of Mechanical and Power Engineering Henan Polytechnic UniversityJiaozuo 454003China

Ultrasonic vibration-assisted ELID(UVA-ELID)grinding is utilized as a novel and highly efficient processing method for hard and brittle materials such as *** this study,the UVA-ELID grinding ZTA ceramics is employed to investigate the influence of thermomechanical loading on the characteristics of oxide *** on the fracture mechanics of material,the model of internal stress for oxide film damage is *** thermomechanical loading is composed of mechanical force and the thermal stress generating from grinding *** theoretical model is established for the mechanical force,thermal stress and internal stress *** the finite element analysis method is used to simulate the theoretical *** mechanical force and grinding temperature is measured during the actual grinding *** the grinding process,the effect of grinding wheel speed and grinding depth on the thermomechanical force and the characteristics of oxide film is *** with the conventional ELID(CELID)grinding,the mechanical force decreased by 25.6%and 22.4%with the increase of grinding wheel speed and grinding depth respectively,and the grinding temperature declined by 10.7%and12.8%during the UVA-ELID *** thermal stress in the latter decreased by 16.3%and20.8%respectively,and internal stress reduced by 12.3%and 15.6%.It was experimentally found that the topographies of oxide layer on the surface of the wheel and the machined surface in the latter was better than that in the *** results indicate that the action of ultrasonic vibration establish a significant effect on the ***,it should be well considered for future reference when processing the ZTA ceramics.

关键词： oxide film Surface quality Thermomechanical loading Ultrasonic vibration-assisted ELID grinding ZTA ceramics

Evolution of Surface oxide film of Typical Aluminum Alloy During Medium-Temperature Brazing Process

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Transactions of Tianjin University 2014年第1期20卷 54-59页

作者：程方杰赵海微王颖肖兵姚俊峰 Tianjin Key Laboratory of Advanced Joining Technology School of Materials Science and Engineering Tianjin University

The evolution of the surface oxide film along the depth direction of typical aluminum alloy under mediumtemperature brazing was investigated by means of X-ray photoelectron spectroscopy(XPS). For the alloy with Mg content below 2.0wt%, whether under cold rolling condition or during medium-temperature brazing process, the enrichment of Mg element on the surface was not detected and the oxide film was pure Al2O3. However, the oxide film grew obviously during medium-temperature brazing process, and the thickness was about 80 nm. For the alloy with Mg content above 2.0wt%, under cold rolling condition, the original surface oxide film was pure Al2O3. However, the Mg element was significantly enriched on the outermost surface during medium-temperature brazing process, and MgO-based oxide film mixed with small amount of MgAl2O4 was formed with a thickness of about 130 nm. The alloying elements of Mn and Si were not enriched on the surface neither under cold rolling condition nor during mediumtemperature brazing process for all the selected aluminum alloy, and the surface oxide film was similar to that of pure aluminum, which was almost entire Al2O3.

关键词： aluminum alloy oxide film phase structure X-ray photoelectron spectroscopy medium-temperaturebrazing

Reaction behavior between the oxide film of LY12 aluminum alloy and the flux

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China Welding 2004年第1期13卷 36-40页

作者：薛松柏董健吕晓春顾文华 Nanjing University of Aeronautics and Astronautics Harbin Welding Institute Changshu Huayin Filler Metal Co. Ltd.

In this paper, the brazing mechanism of LY12 aluminum alloy at middle range temperature was presented. The CsF-AlF_3 non-corrosive flux was utilized to remove the complex oxide film on the surface of LY12 aluminum alloy. The results revealed that the oxide film was removed by the improved CsF-AlF_3 flux accompanied with the occurrence of reaction as well as dissolution and the compounds CsF played an important role to remove the oxide film. Actually, the high activity of flux, say, the ability to remove the oxide film, was due to the presence of the compounds, such as NH_4F,NH_4AlF_4 and composite molten salt. The production of HF was the key issue to accelerate the reaction and enhance to eliminate the oxide film by dissolution. It was found that the rare earth element La at small percentage was not enriched at the interface. Moreover, the rare earth fluoride enhanced the dissolution behavior.

关键词： LY12 aluminum alloy oxide film rare earth fluoride La

oxide film on bubble surface of aluminum foams produced by gas injection foaming process

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Transactions of Nonferrous Metals Society of China 2015年第7期25卷 2429-2437页

作者：周宇通李言祥清华大学材料学院北京100084 清华大学先进成形制造教育部重点实验室北京100084

Based on A356 aluminum alloy,aluminum foams were prepared by gas injection foaming process with pure nitrogen,air and some gas *** oxygen volume fraction of these gas mixtures varied from 0.2%to 8.0%.Optical microscopy,scanning electron microscopy（SEM） and Auger electron spectroscopy（AES） were used to analyze the influence of oxygen content on cell structure,relative density,macro and micro morphology of cell walls,coverage area fraction of oxide film,thickness of oxide film and other *** indicate that the coverage area fraction of oxide film on bubble surface increases with the increase of oxygen content when the oxygen volume is less than 1.2%.While when the oxygen volume fraction is larger than 1.6%,an oxide film covers the entire bubble surface and aluminum foams with good cell structure can be *** thicknesses of oxide films of aluminum foams produced by gas mixtures containing 1.6%-21%oxygen are almost the *** reasons why the thickness of oxide film nearly does not change with the variation of oxygen content and the amount of oxygen needed to achieve 100%coverage of oxide film are both *** addition,the role of oxide film on bubble surface in foam stability is also analyzed.

关键词： aluminum foam gas injection foaming process oxide film foam stability mechanism

PROCESS OF oxide film FORMATION ON JOINT INTERFACE OF METAL AND GLASS

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Transactions of Nonferrous Metals Society of China 1991年第1期1卷 66-72页

作者： Ma Jusheng Kaoru KOJIMA Masayosi TAKADA Dong Zhili Tang Xiangyun Tsinghua University Bey ing 100084China Sumitomo Special Matals Co.Osaka Japan

The *** oxide films on 476 alloy,with a small amount of additive elements such as Si etc.,oxidized in wet hydrogen atmosphere is some times accompanied by the formation of a great many *** form of whiskers grown on the oxide film is of flag pole type with a globe on its *** pole is a spinel single crysul oxide(Fe,Mn)Cr_(2)O_(4) and the globe is a metallic compound(Ni,Fe)_(x)Al_(y) covered with protective Al,Si oxide *** of the metallic globe named while particle is formed at the early stage of heating be tween 700℃ and 900℃.It seems to be extracted from the alloy matrix as a result of arummrum obrusion .Asial growth of pole begins at about 115℃.It is supposed that the whisker grows at the root of a white particle and the interaction effect between the stress of oxide around the particle and the climbing motion of dislocation beneath the *** the alloy surface is covered uniformly with Cr_(2)O_(3) as the ini tai oxide film,its final surface oxide film has no whiskers even after long time oxidation at higher temperature in hydrogen *** surface treatment of base alloy,such mechanical brushing,is very effective for the formation of Cr_(2)O_(3) at initial *** is supposed that the brushed surface may be activated to produce surface reactions by an enrichment of lattice defects.

关键词： sealing alloy oxide film oxide whisker

Effect of depressurizing speed on mold filling behavior and entrainment of oxide film in vacuum suction casting of A356 alloy

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Transactions of Nonferrous Metals Society of China 2016年第12期26卷 3292-3298页

作者： Shan-guang LIU Fu-yang CAO Jun-ying YI Xin-yi ZHAO Jing ZENG Zhi-liang NING Jian-fei SUN School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China National Key laboratory for Precision Hot Processing of Metals Harbin Institute of Technology Harbin 150001 China School of Metallurgical and Materials Engineering Jiangsu University of Science and Technology Zhangjiagang 215600 China

The effect of depressurizing speed on mold filling behavior and entrainment of oxide film of A356 alloy was studied. Themold filling behavior and velocity fields were recorded by water simulation with particle image velocimetry. The results show thatthe gate velocity first increased dramatically, then changed with the depressurizing speed: the gate velocity increased slowly atrelatively high depressurizing speed; at reasonable depressurizing speed, the gate velocity kept unchanged; while at lowerdepressurizing speed, the gate velocity decreased firstly and then kept unchanged. High gate velocity results in melt falling backunder gravity at higher speed. The falling velocity is the main factor of oxide film entrainment in vacuum suction casting. The designcriterion of depressurizing rate was deduced, and the A356 alloy castings were poured to test the formula. The four-point bend testand Weibull probability plots were applied to assessing the fracture mechanisms of the as-cast A356 alloy. The results illuminate amethod on designing suitable depressurizing speed for mold filling in vacuum suction casting.

关键词： A356 aluminum alloy vacuum suction casting water simulation surface turbulence thin-walled casting oxide film

Oxidation kinetics of oxide film on bubble surface of aluminum foams produced by gas injection foaming process

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Transactions of Nonferrous Metals Society of China 2015年第8期25卷 2781-2788页

作者：周宇通李言祥清华大学材料学院北京100084 清华大学先进成型制造教育部重点实验室北京100084

In the range of 620？710 °C, air was blown into A356 aluminum alloy melt to produce aluminum foams. In order to study the influence of temperature on the thickness of oxide film on bubble surface, Auger electron spectroscopy （AES） was used. Based on the knowledge of corrosion science and hydrodynamics, two oxidation kinetics models of oxide film on bubble surface were established. The thicknesses of oxide films produced at different temperatures were predicted through those two models. Furthermore, the theoretical values were compared with the experimental values. The results indicate that in the range of 620？710 °C, the theoretical values of the thickness of oxide film predicted by the model including the rising process are higher than the experimental values. While, the theoretical values predicted by the model without the rising process are in good agreement with the experimental values, which shows this model objectively describes the oxidation process of oxide film on bubble surface. This work suggests that the oxidation kinetics of oxide film on bubble surface of aluminum foams produced by gas injection foaming process follows the Arrhenius equation.

关键词： aluminum foam gas injection foaming process oxide film oxidation kinetics