scholarly journals Quasi-Monocrystalline Graphene Crystallization on Liquid Copper Matrix

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2606
Author(s):  
Dominika Kuten ◽  
Konrad Dybowski ◽  
Radomir Atraszkiewicz ◽  
Piotr Kula
Keyword(s):  
Mechanical Properties ◽  
Liquid Metal ◽  
Degrees Of Freedom ◽  
Liquid Copper ◽  
Copper Matrix ◽  
Crystalline Defects ◽  
Graphene Flakes ◽  
Perfect Graphene ◽  
Influence Of Impurities ◽  
Three Degrees Of Freedom

To access the properties of theoretical graphene, it is crucial to manufacture layers with a defect-free structure. The imperfections of the structure are the cause of deterioration in both electrical and mechanical properties. Among the most commonly occurring crystalline defects, there are grain boundaries and overlapping zones. Hence, perfect graphene shall be monocrystalline, which is difficult and expensive to obtain. An alternative to monocrystalline structure is a quasi-monocrystalline graphene with low angle-type boundaries without the local overlapping of neighboring flakes. The purpose of this work was to identify factors that directly affect the structure of graphene grown on a surface of a liquid metal. In the article the growth of graphene on a liquid copper is presented. Nucleating graphene flakes are able to move with three degrees of freedom creating low-angle type boundaries when they attach to one another. The structure of graphene grown with the use of this method is almost free of overlapping zones. In addition, the article presents the influence of impurities on the amount of crystallization nuclei formed, and thus the possibility to order the structure, creating a quasi-monocrystalline layer.

A Novel 3-DOF Micromanipulator

2003 ◽  
Author(s):  
Heng-Chung Chang ◽  
Julius Ming-Lin Tsai ◽  
Hsin-Chang Tsai ◽  
Weileun Fang
Keyword(s):  
Mechanical Properties ◽  
Degrees Of Freedom ◽  
Single Crystal Silicon ◽  
Robot Arm ◽  
Comb Drive ◽  
Crystal Silicon ◽  
Monolithically Integrated ◽  
Out Of Plane ◽  
Superior Mechanical Properties ◽  
Three Degrees Of Freedom

In this study, a stiff HARM (high aspect ratio micromachining) manipulator is reported. Since the micromanipulator is made of single crystal silicon, it has superior mechanical properties. The micromanipulator is consisted of a position stage and a robot arm. Moreover, the robot arm is monolithically integrated with the position stage through the micromachining fabrication processes. Hence, its in-plane and out-of-plane positions are precisely controlled by two comb drive actuators and a vertical comb, respectively. In applications, the robotarm, which has three degrees of freedom (DOF), can be exploited as a micromanipulator.

scholarly journals Design and Optimization of a Three Degrees-of-Freedom Spatial Motion Compliant Parallel Mechanism With Fully Decoupled Motion Characteristics

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Minh Tuan Pham ◽  
Song Huat Yeo ◽  
Tat Joo Teo ◽  
Pan Wang ◽  
Mui Ling Sharon Nai
Keyword(s):  
Mechanical Properties ◽  
Dynamic Response ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Experimental Results ◽  
Spatial Motion ◽  
Compliant Parallel Mechanism ◽  
Decoupled Motion ◽  
Fast Dynamic ◽  
Three Degrees Of Freedom

This paper presents a novel three degrees-of-freedom (DOF) compliant parallel mechanism (CPM) with a fully decoupled spatial motion (θX−θY−Z) and optimized mechanical properties. To design the CPM using the beam-based structural optimization method, several novel criteria for synthesizing three-legged CPMs with fully decoupled motions are derived. The obtained results suggest that the synthesized CPM delivers a diagonal compliance matrix, a large workspace of 10deg×10deg×7mm, fast dynamic response of ∼100Hz, and good stiffness performance whereby the translational and rotational stiffness ratios are ∼3600 and ∼570, respectively. A prototype of the synthesized CPM is fabricated using one of the three-dimensional (3D) printing technologies, electron beam melting (EBM). Experimental results have shown that the 3D printed CPM can produce the full workspace with deterministic mechanical properties whereby the highest deviations between the theoretical and experimental results are 11.2% and 1% for stiffness and dynamic behaviors, respectively. Importantly, the decoupled-motion characteristic is also verified via an energy approach, i.e., the energies of the undesired parasitic motions are minor (<1%) as compared with the energy of the desired motion. In addition, several comparisons are conducted to clarify the advantages of the synthesized CPM to the existing designs. All these investigations suggest that the proposed CPM can be used in precision positioning systems due to the good stiffness characteristics, large workspace, fast dynamic response, and decoupled output motions.

The effect of pressure on the compressibility of aluminum alloys

2020 ◽  
pp. 102-107
Keyword(s):  
Mechanical Properties ◽  
Mathematical Model ◽  
Liquid Metal ◽  
Control Systems ◽  
Physical And Mechanical Properties ◽  
Reliable Data ◽  
Output Process ◽  
Automated Control ◽  
Input And Output ◽  
Crystallization Under Pressure

To obtain reliable data on the properties of liquid metal and create automated control systems, the technological process of molding with crystallization under pressure is studied. A mathematical model of the input and output process parameters is developed. It is established that the compressibility of the melt can represent the main controlled parameter influencing on the physical-mechanical properties of the final products. The obtained castings using this technology are not inferior in their physical and mechanical properties to those produced by forging or stamping.

scholarly journals Active Disturbance Rejection for a Three Degrees of Freedom Gyroscope

2018 ◽  
Vol 51 (13) ◽  
pp. 372-377 ◽  
Author(s):  
Juan E. Andrade García ◽  
Alejandra Ferreira de Loza ◽  
Luis T. Aguilar ◽  
Ramón I. Verdés
Keyword(s):  
Disturbance Rejection ◽  
Degrees Of Freedom ◽  
Active Disturbance Rejection ◽  
Three Degrees Of Freedom

scholarly journals Synergistic strengthening mechanism of copper matrix composite reinforced with nano-Al2O3 particles and micro-SiC whiskers

2021 ◽  
Vol 10 (1) ◽  
pp. 62-72
Author(s):  
Huanran Lin ◽  
Xiuhua Guo ◽  
Kexing Song ◽  
Jiang Feng ◽  
Shaolin Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Erosion Resistance ◽  
Strengthening Mechanism ◽  
Copper Matrix ◽  
Heavy Duty ◽  
Arc Erosion ◽  
Comprehensive Performance ◽  
Sic Whiskers ◽  
Copper Matrix Composite ◽  
Time And Energy

Abstract Although Cu–Al2O3 composites have good comprehensive performance, higher mechanical properties and arc erosion resistance are still required to meet heavy-duty applications such as electromagnetic railguns. In this work, a novel hybrid SiCw/Cu–Al2O3 composite was successfully prepared by combining powder metallurgy and internal oxidation. The microstructure and mechanical behavior of the SiCw/Cu–Al2O3 composite were studied. The results show that nano-Al2O3 particles and micro-SiCw are introduced into the copper matrix simultaneously. Well-bonded interfaces between copper matrix and Al2O3 particles or SiCw are obtained with improved mechanical and arc erosion resistance of SiCw/Cu–Al2O3 composite. The ultimate tensile strength of the SiCw/Cu–Al2O3 composite is 508.9 MPa, which is 7.9 and 56.1% higher than that of the Cu–Al2O3 composite and SiCw/Cu composite, respectively. The strengthening mechanism calculation shows that Orowan strengthening is the main strengthening mechanism of the SiCw/Cu–Al2O3 composite. Compared with Cu–Al2O3 composite, the hybrid SiCw/Cu–Al2O3 composite has lower arc time and energy and better arc stability.

scholarly journals Cyclic Deformation of Microcantilevers Using In-Situ Micromanipulation

2021 ◽  
Author(s):  
A. H. S. Iyer ◽  
M. H. Colliander
Keyword(s):  
Degrees Of Freedom ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Structural Components ◽  
Cyclic Testing ◽  
Phase Boundaries ◽  
Bulk Specimen ◽  
Arbitrary Position ◽  
Three Degrees Of Freedom

Abstract Background The trend in miniaturisation of structural components and continuous development of more advanced crystal plasticity models point towards the need for understanding cyclic properties of engineering materials at the microscale. Though the technology of focused ion beam milling enables the preparation of micron-sized samples for mechanical testing using nanoindenters, much of the focus has been on monotonic testing since the limited 1D motion of nanoindenters imposes restrictions on both sample preparation and cyclic testing. Objective/Methods In this work, we present an approach for cyclic microcantilever bending using a micromanipulator setup having three degrees of freedom, thereby offering more flexibility. Results The method has been demonstrated and validated by cyclic bending of Alloy 718plus microcantilevers prepared on a bulk specimen. The experiments reveal that this method is reliable and produces results that are comparable to a nanoindenter setup. Conclusions Due to the flexibility of the method, it offers straightforward testing of cantilevers manufactured at arbitrary position on bulk samples with fully reversed plastic deformation. Specific microstructural features, e.g., selected orientations, grain boundaries, phase boundaries etc., can therefore be easily targeted.

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