金属加工表面分形参数尺度独立性的研究

通过结构函数分析法研究了不同采样间距及不同取样长度时金属研磨及刨削加工表面轮廓线的分形特性，分析了采样间距及取样长度对粗糙表面轮廓线分形参数Ｄ及Ｇ值的影响，确定了金属加工表面轮廓线分形参数的尺度独立性。

金属加工表面质量的影响因素及改进措施

金属加工表面质量指的是零件在被加工以后的粗糙度,通过零件的粗糙度可以直接判断被加工的金属的物理性质、化学性质以及其他性质。所以能够通过对金属加工表面质量的影响因素进行分析,从而得出提高产品性能的方法,具有很重要的意义。本文就对金属加工表面直接的影响因素进行分析并且提出一些改进的措施,希望能够对以后的研究提供依据。

金属加工表面质量的影响因素及改进措施

随着社会的不断发展,金属加工行业对于加工标准的要求也是越来越高,而金属在加工过程中可能会因为各种因素的影响而使得自身的表面质量无法达到应有的标准,严重影响到了金属相关行业未来的发展,只有根据其相关的影响因素采取对应的改进措施,才能够更好的保证金属加工表面的质量。因此本文将通过金属加工表面质量对零件使用性能的影响、金属加工表面质量的影响因素以及改进措施等几个方面对其进行具体的研究分析,希望能够为金属加工表面质量的提升贡献自己的一份力量。

金属加工表面缺陷检测综述

考虑到金属加工表面缺陷检测在实际生产中具有重要意义,本文通过调研国内外文献,对金属表面缺陷检测进行了全面的总结。检测方式包括传统人工检测、物理机理检测以及机器视觉检测。重点分析了基于图像的机器视觉在金属加工表面缺陷的应用现状,并对金属加工表面缺陷检测未来的研究提出了展望。

浅谈金属加工表面质量的影响因素及改进措施

现阶段金属材料应用范围逐步扩大,导致金属加工表面质量不佳等影响因素更多。通过分析金属加工表面粗糙度,可直接判别被加工金属材料的物理、化学性质,制定出能够增强产品各项性能的方式。本文就针对此,首先提出金属加工表面质量概念,分析影响金属加工表面质量的各类因素,提出金属加工表面质量质量改进与管控措施,以期为相关工作人员提供理论性帮助。

A novel method to improve interfacial bonding of compound squeeze cast Al/Al-Cu macrocomposite bimetals:Simulation and experimental studies

A facile and innovative method to improve bonding between the two parts of compound squeeze cast Al/Al-4.5 wt.%Cu macrocomposite bimetals was developed and its effects on microstructure and mechanical properties of the bimetal were investigated.A special concentric groove pattern was machined on the top surface of the insert(squeeze cast Al-4.5 wt.%Cu) and its effects on heat transfer,solidification and distribution of generated stresses along the interface region of the bimetal components were simulated using ProCAST and ANSYS softwares and experimentally verified. Simulation results indicated complete melting of the tips of the surface grooves and local generation of large stress gradient fields along the interface. These are believed to result in rupture of the insert interfacial aluminum oxide layer facilitating diffusion bonding of the bimetal components. Microstructural evaluations confirmed formation of an evident transition zone along the interface region of the bimetal. Average thickness of the transition zone and tensile strength of the bimetal were significantly increased to about 375 μm and 54 MPa, respectively, by applying the surface pattern.The proposed method is an affordable and promising approach for compound squeeze casting of Al-Al macrocomposite bimetals without resort to any prior cost and time intensive chemical or coating treatments of the solid insert.

Conception of tooling adapted to thixoforging of high solid fraction hot-crack-sensitive aluminium alloys

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.7<φs<1), which involves the processing of alloys in the semi-solid state.Tooling has to be adapted to this particular process to benefit shear thinning and thixotropic behaviour of such semi-solid material.Tooling parameters, such as the forming speed and tool temperature, have to be accurately controlled because of their influence on thermal exchanges between material flow and tool.These thermal exchanges influence the high-cracking tendency and the rheology of the semi-solid material during forming, which affects parts properties and therefore their quality.Extrusion tests show how thermal exchanges influence quality of thixoforged parts made of 7075 aluminium alloys at high solid fraction by modifying process parameters like forming speed, tool temperature and tool thermal protector.Thus an optimum in terms of thermal exchanges has to be found between surface quality and mechanical properties of the part.A direct application is the evaluation of surface quality of thixoforged thin wall parts made of 7075 aluminium alloy.

Parametric optimization of electrochemical machining of Al/15% SiC_p composites using NSGA-Ⅱ

Electrochemical machining（ECM） is one of the important non-traditional machining processes,which is used for machining of difficult-to-machine materials and intricate profiles.Being a complex process,it is very difficult to determine optimal parameters for improving cutting performance.Metal removal rate and surface roughness are the most important output parameters,which decide the cutting performance.There is no single optimal combination of cutting parameters,as their influences on the metal removal rate and the surface roughness are quite opposite.A multiple regression model was used to represent relationship between input and output variables and a multi-objective optimization method based on a non-dominated sorting genetic algorithm-Ⅱ（NSGA-Ⅱ） was used to optimize ECM process.A non-dominated solution set was obtained.

Study on GNi-WC25 Coating by High Frequency Induction Cladding

Process and mechanism of high frequency were studied in this paper by means of cold attachment for the preparation of GNi WC25 coating . The results show its special distribution law of eddy current while the magnetic transition temperature and electric resistivity of the coating have been measured .Wear resistance of the high frequency induction coating has an advantage over those of laser cladding coating and oxygen acetylene spraying fusing coating . Moreover , the GNi WC25 coating by high frequency induction cladding has smooth surface and even microstructure.

Highly structured metal-organic framework nanofibers for methane storage

Porous materials such as metal-organic frameworks(MOFs)with high theoretical volumetric gas uptake capacity are promising materials for gas storage and separation,but the structuring for practical applications is challenging.Herein,we report a general and feasible strategy to combine electrospinning with a phase conversion method to decorate polyacrylonitrile nanofibers(PAN NFs)with CuMOF(HKUST-1).The strategy is based on the combination of surface pretreatment of the NFs with Cu(OH)_(2) and a subsequent phase conversion into HKUST-1 crystals(PCHKUST-1).A significant higher loading of HKUST-1 in the PAN NF matrix was achieved by the phase conversion method compared with direct electrospinning of MOF slurries or insitu growth of MOF crystals on NFs.As a result,the hierarchical structured PC(phase conversion)-HKUST-1 NFs revealed the highest gravimetric storage capacity of 86 cm^(3) g^(-1)(STP)at 3500 kPa and 298 K for methane(CH_(4)),which is higher than other HKUST-1 NFs reported previously.The improved CH_(4) uptake can be explained by the high loading of HKUST-1 due to the high availability of Cu-ions localized on the surface of the NFs during the phase conversion process,resulting in high surface area and excellent gas access of the phase converted HKUST-1.Thus,the developed strategy of structuring MOFs could be of interest for the fabrication of tailor-made MOF NF architectures for other energy and environmental applications.