Mechanochemistry with solvent‐free and environmentally friendly characteristics is one of the most promising alternatives to traditional liquid‐phase‐based reactions, demonstrating epoch‐making ...significance in the realization of different types of chemistry. Mechanochemistry utilizes mechanical energy to promote physical and chemical transformations to design complex molecules and nanostructured materials, encourage dispersion and recombination of multiphase components, and accelerate reaction rates and efficiencies via highly reactive surfaces. In particular, mechanochemistry deserves special attention because it is capable of endowing energy materials with unique characteristics and properties. Herein, the latest advances and progress in mechanochemistry for the preparation and modification of energy materials are reviewed. An outline of the basic knowledge, methods, and characteristics of different mechanochemical strategies is presented, distinguishing this review from most mechanochemistry reviews that only focus on ball‐milling. Next, this outline is followed by a detailed and insightful discussion of mechanochemistry‐involved energy conversion and storage applications. The discussion comprehensively covers aspects of energy transformations from mechanical/optical/chemical energy to electrical energy. Finally, next‐generation advanced energy materials are proposed. This review is intended to bring mechanochemistry to the frontline and guide this burgeoning field of interdisciplinary research for developing advanced energy materials with greener mechanical force.
Mechanochemistry as a powerful tool to prepare advanced energy materials is reviewed, covering specific aspects of energy transformations from mechanical/optical/chemical energy to electrical energy. This review intends to comprehensively clarify mechanism, features, and methods of mechanochemistry and summarize the latest advances and progress in this field to inspire interdisciplinary research for developing novel energy materials with greener mechanical force.
We proposed a new processing method to reduce the cutting force of the machining process effectively, as well as to improve tool life and machining process efficiency. The proposed method, called the ...milling–milling machining method, is a new form of composite machining that is similar to the turn-milling method. It combines the advantages of face milling and helical end-milling cutters and uses the synthesis motion of these kinds of cutters to complete surface processing. This technique effectively reduces cutting force and, thus, improves tool life and machining efficiency. The milling–milling machining method has the advantages of a large diameter face mill with a large milling area, a low cutting force, a stable and highly efficient cutting process that is similar to that of a helical end-milling cutter, and trochoidal milling. The outstanding characteristics of face milling and helical end-milling cutters can be applied directly to the milling–milling machining method. In addition, the proposed method has unique features. The up–down milling–milling machining method can offset a portion of the cutting forces. Apart from proposing the theory for the milling–milling machining method, we also designed new equipment, namely the planetary cutter, milling–milling driving head, and a computer numerically controlled milling–milling machine. We compared the proposed method and the common face milling method from the perspective of cutting forces. Experimental results show that the milling–milling machining method considerably reduces cutting forces compared with conventional methods.
Micro milling cutters or micro mills are unique and important micro tools for fabricating miniaturised devices with sufficient geometrical and dimensional accuracy and machined surface integrity. ...Micro milling cutters, compared to conventional macro tools, have significantly different material removal mechanisms. They are also made of different raw materials and structures and exhibit distinctive machining characteristics and performances. Herein, we present the first comprehensive and up-to-date review of micro milling cutters in terms of their uniqueness, material removal mechanisms, materials and compositions, structures and design, fabrication techniques and machining performances, to provide adequate guidance for interested involvers. We also outline and discuss several possible future research directions to offer potential insights for the micro milling community and future researchers.
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•Uniqueness of micro mills compared with ordinary macro tools are analyzed.•Material removal mechanisms of micro milling with emphasis on size effect are summarized.•Raw material types, structures, and design methodologies for micro mills are investigated.•Fabrication technologies, performances, and application of micro mills are discussed.•Possible future research or engineering directions are outlined.
Graphite‐to‐Graphene: Total Conversion Buzaglo, Matat; Bar, Ilan Pri; Varenik, Maxim ...
Advanced materials (Weinheim),
02/2017, Letnik:
29, Številka:
8
Journal Article
Recenzirano
The rush to develop graphene applications mandates mass production of graphene sheets. However, the currently available complex and expensive production technologies are limiting the graphene ...commercialization. The addition of a protective diluent to graphite during ball‐milling is demonstrated to result in a game‐changer yield (>90%) of defect‐free graphene, whose size is controlled by the milling energy and the diluent type.
•Evaluation of relations between tool displacements and surface profile formation.•Novel method for measurement of ball end mill’s working part displacements.•Two distinct mechanisms of surface ...profile formation depended on tool overhang.•High effect of cutting speed on surface roughness in milling with flexible tool.
The study presents an analysis of relations between the instantaneous tool displacements and surface roughness formed during ball end milling of surface with inclination towards the tool’s axis. A novel experimental method for the estimation of ball end mill’s working part vibrations, considering displacements correlated with the geometrical errors of tool-toolholder-spindle system and deflections caused by milling forces has been proposed. The experiments have been conducted on hard-to-cut low carbon hardened alloy steel. Milling tests involved the use of monolithic ball end mills varied in terms of overhang l values. In the first stage, the finishing machining of inclined surface with variable cutting speeds vc was carried out. During the experiment, the instantaneous tool’s joining part displacements have been measured with the application of laser displacements sensor. Subsequently, in order to obtain the tool’s tip instantaneous displacements, the analytical extrapolation method has been proposed. In the next stage, the machined surface roughness has been measured with the application of stylus and optical profile meters. The investigations show that the value of tool’s overhang significantly affects the mechanisms of surface roughness generation during finishing ball end milling. In case of milling with the rigid tool (l = 35 mm), the surface roughness is strongly correlated with kinematic-geometric model, as well as with geometrical errors of machining system. Nevertheless, in case of milling with the slender tool (l = 85 mm), the surface roughness formation is mainly affected by the tool’s working part dynamic deflections caused by milling forces.
Mechanics of turn-milling operations Comak, Alptunc; Altintas, Yusuf
International journal of machine tools & manufacture,
October 2017, 2017-10-00, 20171001, Letnik:
121
Journal Article
Recenzirano
Turn-milling machines, which are capable of carrying out turning and milling operations, are widely used in machining complex parts in one set-up. However, due to the complex kinematics and ...tool-workpiece interaction, turn milling operations are mainly carried out by relying on costly machining trials and experience. This paper presents the mechanics of turn-milling operations to predict cutting forces, torque and power requirements. Typical turn milling process involves three linear (x,y.z) and two rotary drives of the machine tool. The resulting feed vector is modeled as a function of linear velocities of the drives, and angular speeds of workpiece and tool spindles. The generalized chip thickness distribution is modeled as a function of linear feed drive motions, tool and workpiece spindle rotations. The cutting force predictions are experimentally verified for sample cylindrical and ball end mills. The identification of productive tool and workpiece spindle speeds is demonstrated using chip load limit of the tools and torque-power constraints of the turn milling machine tools.
•Generalized mechanics model of the turn-milling process is proposed.•Chip thickness is modeled as a function of drive motions and tool-workpiece speeds.•Productive tool and workpiece spindle speeds are demonstrated.
•An integrated multi-objective optimization method is developed.•Surface integrity of multi-axis ball-end milling Inconel 718 is optimized.•Grey relational grade is significantly improved by ...62.87%.•The proposed method shows a larger advantage than that of the original GRA.
Multi-axis ball-end milling is the most commonly used operation in machining aerospace engine parts. Because of multi-output characteristic, the process improvement often requires multi-objective optimization. Recently, the grey relational analysis (GRA) has been more and more widely used in engineering manufacture with multiple responses. But, the original GRA method only suits for the optimization problem in discrete space. This paper proposes an integrated multi-objective optimization method with GRA, radial basis function (RBF) neural network, and particle swarm optimization (PSO) algorithm. Compared with the original GRA, it expands the optimal solution space to continuous space. This approach is subsequently applied to the multi-objective optimization of multi-axis ball-end milling Ni-based superalloy Inconel 718. The purpose is to simultaneously obtain minimum surface roughness and maximum compressive residuals tress by optimizing the inclination angle, cutting speed, and feed. A hybrid experiment scheme with single factor design and orthogonal array is utilized to generate the sample data set. The multi-response optimization problem is successfully converted into the single objective optimization of grey relational grade (GRG). Then, the RBF neural network is employed to establish the mapping relation between the GRG and the process parameters. And its adequacy is proved by five test experiments with a low prediction error of 6.86%. Finally, the PSO algorithm is adopted to optimize the process parameters. Verification experiments show that a higher improvement of the GRG is obtained with the proposed method (62.87%) than that of the original GRA (50.00%). The developed approach is proved to be feasible and can be generalized for other multi-objective optimization problem in manufacturing industry.
In the high speed milling, the tool run-out affects the cutting force greatly and results in pre-matured tool life. To investigate this relationship, an improved instantaneous milling force per tooth ...is proposed, with inclusion of tool run-out effect. The un-deformed chip thickness considering tool run-out are defined and modeled, according to the geometrical relationships and axial milling ranges per tooth. Meanwhile, instead of the studying the conventional average flank wear, tool wear per tooth is studied for more sensitive correlation with force. Based on milling tests with Inconel 718, the error of the force model prediction is found less than 1% against the experimental data, and the correlation between the axial instantaneous milling force and tool wear per tooth is above 0.9. The results have shown that the proposed model can accurately describe the instantaneous force per tooth including tool run out effect, and the axial force component is a good indication of tool wear condition.
•Modeled the instantaneous force per tooth in milling, with run-out effect considerations.•Determined explicitly the upper and lower boundaries of the cutter-workpiece engagement.•Validated the model's accuracy with experimental data.•Identified that the z-axial instantaneous force sensitive to tool wear per tooth.
Ceramic tool materials become an ideal choice for machining superalloy materials because of the excellent tolerance to effect of heat, strong chemical stability and high temperature hardness. The ...present paper focuses on the effects of different cutting environments which are the dry, MQL (pure-oil) and MQL mixed with water on the milling force in each direction, the variation of flank wear, as well as surface topography of workpiece, simultaneously analyzing in deep to the wear mechanism of the mills during distinct technological environments. The results reveal that the milling force of MQL and MQL mixed with water conditions were decreased by 12.8% and 28.2% respectively compared with the dry milling. In terms of the cutting temperature, it was also significantly reduced up to 9.2% and 17.5% separately. In addition, MQL and MQL mixed with water had been successful in improving the surface quality of the workpiece and limiting the tool wear values. Similar to the tool wear mechanism of dry milling, the wear mechanisms of ceramic end mills under MQL and MQL mixed with water were deemed adhesive wear, diffusion wear and notch wear.
•The wear mechanism of ceramic end milling tools under dry milling and MQL condition is studied.•The wear degree of ceramic end milling tools is the lowest in the MQL mixing with water condition.•The cutting temperature and cutting force decreased significantly under MQL conditions.•Surface quality and tool life are improved due to the lubrication and wear reduction of MQL.•The cutting environment of MQL mixed with water is crucial to raise the cutting performance of ceramic end mills.
Metal‐free elemental photocatalysts for hydrogen (H2) evolution are more advantageous than the traditional metal‐based inorganic photocatalysts since the nonmetal elements are generally cheaper, more ...earth‐abundant, and environmentally friendly. Black phosphorus (BP) has been attracting increasing attention in recent years based on its anisotropic 2D layered structure with tunable bandgap in the range of 0.3–2.0 eV; however, the application of BP for photocatalytic H2 evolution has been scarcely reported experimentally although being theoretically predicted. Herein, for the first time, the visible light photocatalytic H2 evolution of BP nanosheets prepared via a facile solid‐state mechanochemical method by ball‐milling bulk BP is reported. Without using any noble metal cocatalyst, the visible light photocatalytic hydrogen evolution rate of BP nanosheets reaches 512 µmol h−1 g−1, which is ≈18 times higher than that of the bulk BP, and is comparable or even higher than that of graphitic carbon nitrides (g‐C3N4).
Black phosphorus (BP) is discovered as the missing metal‐free elemental photocatalyst. Few‐layer BP nanosheets are prepared via a facile solid‐state mechanochemical method, exhibiting a visible light H2 evolution rate of 512 µmol h−1 g−1 without using any noble metal cocatalyst, which is increased by ≈18 times relative to that of bulk BP. Thus the missing photocatalytic property of BP is discovered.
