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Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

Ming CHEN, Yuezhou MA, Yuan HAO,

《机械工程前沿(英文)》 2010年 第5卷 第1期   页码 98-105 doi: 10.1007/s11465-009-0088-8

摘要: To study the requirements of the power supply in micro-arc oxidation (MAO) of magnesium alloy, many experiments were performed under the DC, unipolar, and ambipolar pulse output modes. Based on the experimental results and electric arc theory, the separate local arc discharge mechanism was put forward. It is considered that magnesium MAO process consists of three stages including anodic oxidation, micro-arc oxidation, and large-arc discharge in turn with increasing source voltage. The MAO film is composed of metal oxides that resulted from numerous discrete local arc discharges, which accumulate the non-equilibrium structure after undergoing sudden heating and cooling cycles. Separate local arc discharge is caused by the process in which the oxygen-based gas is ionized in the conduct channel bearing electric field intensity, changed from insulator to conductor that presents sharp negative resistance effect, and produced partially high temperature to ignite locally metal oxidation. The local arc discharge model is described as four courses: gas created from electrolysis, arc discharge, metals oxidization, and cooling and shrinking of oxides. The purpose of pulse supply is to inhibit the large-arc discharge by intervening proper cooling time, which cannot be actualized by a unipolar pulse mode because of the strong capacitive load characteristics but can be reached by an ambipolar pulse supply because the negative pulse period acts as cooling time. Using a discharge loop to remove the influence of load capacitive, a new type of pulse power supply for MAO is developed, so that the large-arc problem is resolved effectively, the film-forming efficiency is improved, and the pollution of the film and electrolyte caused by negative voltage is avoided.

关键词: micro-arc oxidation     local arc discharge     pulse power supply     magnesium alloy    

Effect of electrolyte concentration on the tribological performance of MAO coatings on aluminum alloys

Chao Wang, Jun Chen, Jihua He, Jing Jiang, Qinyong Zhang

《化学科学与工程前沿(英文)》 2020年 第14卷 第6期   页码 1065-1071 doi: 10.1007/s11705-019-1909-x

摘要: Micro-arc oxidation (MAO) is an efficient approach to improve the hardness, wear resistance, and other properties of aluminum alloys. In order to investigate the effect of the electrolyte concentration on the properties of MAO coatings for LY12 alloy, the voltage variation during the MAO process was recorded. The surface morphologies and phase compositions of the coatings produced with different electrolytes were investigated using scanning electron microscopy and X-ray diffraction, respectively. The roughness and thickness of the coatings were measured using a pocket roughness meter and an eddy-current thickness meter, respectively. The tribological performances of the coatings were investigated against GCr15 bearing steel on a ball-on-disc wear tester in open air. The results showed that with an increase in the Na SiO content, the working voltage of the MAO process decreased, the roughness and thickness of the coatings increased significantly, and the relative content of the -Al O phase decreased. With an increase in the KOH content, the working voltage decreased slightly, the roughness and thickness of the coatings increased slightly, and the α- and -Al O phase contents remained unchanged. The friction coefficient and wear rate of the coatings increased with an increase in the Na SiO and KOH concentrations. A decrease in the porosity and roughness and an increase in the α-Al O content of the coatings reduced their wear mass loss.

关键词: aluminum alloy     micro-arc oxidation     coating     electrolyte concentration     tribological performance    

Submerged arc plasma system combined with ozone oxidation for the treatment of wastewater containing

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期 doi: 10.1007/s11783-020-1384-0

摘要:

• Submerged arc plasma was introduced in terms of wastewater treatment.

关键词: Thermal plasma     Submerged arc plasma     Wastewater     Ozone     Phenol     Highly energetic electron    

Stress field near circular-arc interface crack tip based on electric saturation concept

Longchao DAI, Xinwei WANG

《机械工程前沿(英文)》 2009年 第4卷 第3期   页码 320-325 doi: 10.1007/s11465-009-0042-9

摘要: Within the framework of nonlinear electroelasticity, the anti-plane problem of a circular-arc interfacial crack between a circular piezoelectric inhomogeneity and an infinite piezoelectric matrix subjected to a far-field uniform loading is investigated by an electrical strip saturation model, the complex variable method, and the method of analytical continuation. Explicit closed form expressions for the complex potentials in both the matrix and the inclusion, and the stress intensity factor at the crack tip are presented. Comparison with some related solutions based on the linear electroelastic theory shows the validity of the present solutions

关键词: piezoelectric material     arc crack     strip saturation     stress intensity factor    

Development of a new wear resistant coating by arc spraying of a steel-based cored wire

Lidong ZHAO, Pia KUTSCHMANN, Binyou FU, Dingyong HE

《机械工程前沿(英文)》 2009年 第4卷 第1期   页码 1-4 doi: 10.1007/s11465-009-0012-2

摘要: In the present study, a cored wire of 304 L stainless steel as sheath material and NiB and WC-12Co as filler materials was designed and deposited to produce a new wear resistant coating containing amorphous phase by arc spraying. The microstructure of the coating was investigated. The porosity and hardness of the coating were determined. The wear performance of the coating was evaluated. The XRD and TEM analyses showed that there are high volume of amorphous phase and very fine crystalline grains in the coating. DTA measurements revealed that the crystallization of the amorphous phase occurred at 579.2°C. Because metallurgical processes for single droplets were non-homogenous during spraying, the lamellae in the coating have different hardness values, which lie between about 700 and 1250 HV . The abrasive wear test showed that the new Fe-based coating was very wear resistant.

关键词: amorphous phase     arc spraying     microstructure     wear     cored wire    

Experimental and modeling studies on installation of arc sprayed Zn anodes for protection of reinforced

Xianming SHI

《结构与土木工程前沿(英文)》 2016年 第10卷 第1期   页码 1-11 doi: 10.1007/s11709-016-0312-7

摘要: Arc sprayed zinc (Zn) anode on concrete surfaces has been an emerging technology for protecting reinforced concrete structures from rebar corrosion in coastal environments. Many cathodic protection (CP) systems with arc sprayed Zn anodes will reach or exceed their design life in the near future and thus may function improperly or insufficiently, making it necessary to replace the aged anodes. However, prior to this study, little was known about the most effective profile for the concrete surface, for either new concrete or old concrete with existing Zn anodes removed. This work develops criteria to properly prepare the concrete surface before the application of new Zn anode. Experimental studies were conducted both in the laboratory and for a field structure in Oregon. Artificial neural network was used to achieve better understanding of the complex cause-and-effect relationships inherent in the Zn-mortar or Zn–concrete systems and was successful in finding meaningful, logical results from the bond strength data. The goal is to achieve strong initial bond strength of new Zn to concrete, which is essential for long-term performance of the CP system. The results from this case study suggest that it is necessary to adjust the anode removal and surface sandblasting based on the electrochemical age of the existing concrete. In all cases of sandblasting, minimize the exposure of large aggregates (e.g., those bigger than 19 mm in diameter).

关键词: arc sprayed Zn     anode replacement     reinforced concrete     bridge preservation     neural networks     surface profile    

Mathematical model and manufacture programming of loxodromic-type normal circular-arc spiral bevel gear

Zhenyun DUAN, Houjun CHEN, Zhilan JU, Jian LIU

《机械工程前沿(英文)》 2012年 第7卷 第3期   页码 312-321 doi: 10.1007/s11465-012-0308-5

摘要:

In this paper, loxodromic-type normal circular-arc spiral bevel gear is proposed as a novel application of the circular-arc tooth profile at the gear transmission with intersecting axes. Based on the principle of molding-surface conjugation, the study develops a mathematical model for the tooth alignment curve and the computational flow at the design stage to enable the generation of the tooth surface. Machining of the tooth surface is then carried out to determine the interference-free tool path of the numerical control (NC). Moreover, a pair of loxodromic-type normal circular-arc spiral bevel gears is manufactured on computer numerical control (CNC) machine tools. The proposed theory and method are experimentally investigated, and the obtained results primarily reflect the superior performance of the proposed novel gear.

关键词: loxodrome     circular-arc tooth profile     Wildhaber-Novikov (W-N) gear     spiral bevel gear    

高强钢筋混凝土预制弧板井壁力学特性分析

荣传新,王秀喜,程桦

《中国工程科学》 2005年 第7卷 第7期   页码 43-49

摘要:

对高强钢筋混凝土预制弧板井壁结构的研究表明,实验结果与数值计算结果基本一致。高强钢筋混凝土预制弧板井壁结构具有很高的承载能力,影响其承载能力的主要因素依次为混凝土的强度等级、厚径比和配筋率。在均布荷载作用下,混凝土的强度等级提高10MPa,极限承载力提高1.26MPa。厚径比每增加1%,极限承载力增加0.85 MPa。增大配筋率对提高其极限承载力作用不大,配筋率增大3倍,极限承载力只增加了0.1MPa。

关键词: 高强钢筋混凝土预制弧板井壁     力学特性     有限元法     ANSYS    

ARC welding method for bonding steel with aluminum

Zhenyang LU, Pengfei HUANG, Wenning GAO, Yan LI, Hanpeng ZHANG, Shuyan YIN

《机械工程前沿(英文)》 2009年 第4卷 第2期   页码 134-146 doi: 10.1007/s11465-009-0033-x

摘要: When welding steel with aluminum, the appearance of intermetallic compounds of Fe and Al will decrease tenacity and increase rigidity, which leads to bad joint performance. A new type of low energy input (LEI) welding technology is introduced which can be used to weld steel with aluminum. Using the technology, brazing was located on the steel side and arc fusion welding on the aluminum side. The less heat input reduces the thickness of intermetallic compounds to 3-4 μm. Tensile strength tests prove that the joint breaks at the heat-affected zone and the strength is higher than 70% of the aluminum’s. Thus, the method can lead to a good performance joint.

关键词: joining of steel and aluminum     low energy input welding     arc welding     fusion welding – brazing    

Flexible micro flow sensor for micro aerial vehicles

Rong ZHU, Ruiyi QUE, Peng LIU

《机械工程前沿(英文)》 2017年 第12卷 第4期   页码 539-545 doi: 10.1007/s11465-017-0427-0

摘要:

This article summarizes our studies on micro flow sensors fabricated on a flexible polyimide circuit board by a low-cost hybrid process of thin-film deposition and circuit printing. The micro flow sensor has merits of flexibility, structural simplicity, easy integrability with circuits, and good sensing performance. The sensor, which adheres to an object surface, can detect the surface flow around the object. In our study, we install the fabricated micro flow sensors on micro aerial vehicles (MAVs) to detect the surface flow variation around the aircraft wing and deduce the aerodynamic parameters of the MAVs in flight. Wind tunnel experiments using the sensors integrated with the MAVs are also conducted.

关键词: micro flow sensor     flexible sensor     surface flow sensing     aerodynamic parameter     micro aerial vehicle (MAV)    

新型弧焊电源及其智能控制

黄石生,薛家祥,余文松,陈延明

《中国工程科学》 2000年 第2卷 第4期   页码 70-74

摘要:

重点介绍了弧焊逆变器新的发展方向--软开关相移PWM控制技术,给出了一个具体的电路实例和试验结果;分析了弧焊逆变器动态过程的仿真技术和模糊逻辑控制方法,为新型弧焊逆变器的研制提供了一种新思路。

关键词: 弧焊逆变器     软开关     动态过程仿真     模糊控制    

A novel soft-switching twin arc pulse MAG welding inverter

WANG Zhenmin, XUE Jiaxiang, WANG Fuguang, HUANG Shisheng

《机械工程前沿(英文)》 2007年 第2卷 第2期   页码 224-227 doi: 10.1007/s11465-007-0039-1

摘要: The high-speed double wire pulse metal gas arc (MAG) welding process possesses advantages of automation and high efficiency and quality. Thus, it attracts much more attention nowadays. To meet the requirements of the double wire pulse MAG welding process, a novel double wire pulse MAG welding inverter integrated with technologies, such as soft-switching, double closed loop control, and synchronic control, is produced. A complete performance test was done for the pulsed MAG welding power supply by using a computer testing platform. The results of the experiment indicate that the novel welding inverter has an excellent performance both in the dynamic and the static characteristics. Also, the synchronic control between the master inverter and the slave inverter is reliable.

关键词: high-speed     control     computer     experiment indicate     platform    

Dependence of error sensitivity of frequency on bias voltage in force-balanced micro accelerometer

Lili CHEN, Wu ZHOU

《机械工程前沿(英文)》 2013年 第8卷 第2期   页码 146-149 doi: 10.1007/s11465-013-0260-z

摘要:

To predict more precisely the frequency of force-balanced micro accelerometer with different bias voltages, the effects of bias voltages on error sensitivity of frequency is studied. The resonance frequency of accelerometer under closed loop control is derived according to its operation principle, and its error sensitivity is derived and analyzed under over etching structure according to the characteristics of Deep Reaction Ion Etching (DRIE). Based on the theoretical results, micro accelerometer is fabricated and tested to study the influences of AC bias voltage and DC bias voltage on sensitivity, respectively. Experimental results indicate that the relative errors between test data and theory data are less than 7%, and the fluctuating value of error sensitivity under the range of voltage adjustment is less than 0.01 μm . It is concluded that the error sensitivity with designed parameters of structure, circuit and process error can be used to predict the frequency of accelerometer with no need to consider the influence of bias voltage.

关键词: Micro-Electro-Mechanical Systems (MEMS)     micro accelerometer     force-balanced micro accelerometer     frequency     error sensitivity    

Dilution rate and microstructure of TIG arc Ni-Al powder surfacing layer

SHAN Jiguo, DONG Wei, TAN Wenda, ZHANG Di, REN Jialie

《机械工程前沿(英文)》 2007年 第2卷 第1期   页码 20-24 doi: 10.1007/s11465-007-0003-0

摘要: Surfacing beads are prepared by a direct current tungsten inert gas arc nickel-aluminum (Ni-Al) powder surfacing process. With the aim of controlling the dilution rate and obtaining surfacing beads rich in intermetallic compounds, the effects of surfacing parameters on geometric parameters, dilution rate, composition, and microstructure of the bead are investigated. An assistant cooler, which can potentially reduce the temperature of the base metal, is used in the surfacing process and its effect on dilution rate and microstructure is studied. The result indicates that with the surfacing parameter combination of low current and speed, the width and penetration of the bead decrease, reinforcement increases, and dilution rate drops markedly. With the reduction of the parameter combination, the intergranular phase ?-(Fe, Ni) is formed in the grain boundaries of Ni-Al intermetallic matrix instead of the intergranular phase ?-Fe, and large amount of intermetallics are obtained. With the use of an assistant cooler on a selected operation condition during the surfacing process, the reinforcement of the bead increases, penetration decreases, and dilution rate declines. The use of an assistant cooler helps obtain a surfacing bead composed of only intermetallics.

关键词: decrease     Ni-Al     surfacing parameter     temperature     surfacing process    

FootNote> Project supported by CAPES-PDSE (No. 4926145), CNPq (Nos. 448462/2014-1 and 306301/2012-1) and ARCARC-13-009716-01) A preliminary version was presented at the 13th International

Maiquel DE BRITO,Lauren THÉVIN,Catherine GARBAY,Olivier BOISSIER,Jomi Fred HÜBNER

《信息与电子工程前沿(英文)》 2016年 第17卷 第4期   页码 309-324 doi: 10.1631/FITEE.1500369

摘要: This paper highlights the use of situated artificial institution (SAI) within a hybrid, interactive,normative multi-agent system to regulate human collaboration in crisis management. Norms regulate the actions of human actors based on the dynamics of the environment in which they are situated. This dynamics results from both environment evolution and actors’ actions. Our objective is to situate norms in the environment in order to provide a context-aware crisis regulation. However, this coupling must be a loose one to keep both levels independent and easyto-change in order to face the complex and changing crisis situations. To that aim, we introduce a constitutive level between environmental and normative states providing a loose coupling of normative regulation with environment evolution. Norms are thus no more referring to environmental facts but to status functions, i.e., the institutional interpretation of environmental facts through constitutive rules. We present how this declarative and distinct SAI modelling succeeds in managing the crisis with a context-aware crisis regulation.

关键词: Situated artificial institutions (SAIs)     Normative system     Tangible interaction     Crisis management    

标题 作者 时间 类型 操作

Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

Ming CHEN, Yuezhou MA, Yuan HAO,

期刊论文

Effect of electrolyte concentration on the tribological performance of MAO coatings on aluminum alloys

Chao Wang, Jun Chen, Jihua He, Jing Jiang, Qinyong Zhang

期刊论文

Submerged arc plasma system combined with ozone oxidation for the treatment of wastewater containing

期刊论文

Stress field near circular-arc interface crack tip based on electric saturation concept

Longchao DAI, Xinwei WANG

期刊论文

Development of a new wear resistant coating by arc spraying of a steel-based cored wire

Lidong ZHAO, Pia KUTSCHMANN, Binyou FU, Dingyong HE

期刊论文

Experimental and modeling studies on installation of arc sprayed Zn anodes for protection of reinforced

Xianming SHI

期刊论文

Mathematical model and manufacture programming of loxodromic-type normal circular-arc spiral bevel gear

Zhenyun DUAN, Houjun CHEN, Zhilan JU, Jian LIU

期刊论文

高强钢筋混凝土预制弧板井壁力学特性分析

荣传新,王秀喜,程桦

期刊论文

ARC welding method for bonding steel with aluminum

Zhenyang LU, Pengfei HUANG, Wenning GAO, Yan LI, Hanpeng ZHANG, Shuyan YIN

期刊论文

Flexible micro flow sensor for micro aerial vehicles

Rong ZHU, Ruiyi QUE, Peng LIU

期刊论文

新型弧焊电源及其智能控制

黄石生,薛家祥,余文松,陈延明

期刊论文

A novel soft-switching twin arc pulse MAG welding inverter

WANG Zhenmin, XUE Jiaxiang, WANG Fuguang, HUANG Shisheng

期刊论文

Dependence of error sensitivity of frequency on bias voltage in force-balanced micro accelerometer

Lili CHEN, Wu ZHOU

期刊论文

Dilution rate and microstructure of TIG arc Ni-Al powder surfacing layer

SHAN Jiguo, DONG Wei, TAN Wenda, ZHANG Di, REN Jialie

期刊论文

FootNote> Project supported by CAPES-PDSE (No. 4926145), CNPq (Nos. 448462/2014-1 and 306301/2012-1) and ARCARC-13-009716-01) A preliminary version was presented at the 13th International

Maiquel DE BRITO,Lauren THÉVIN,Catherine GARBAY,Olivier BOISSIER,Jomi Fred HÜBNER

期刊论文