scholarly journals Evaluation of Warpage and Residual Stress of Precision Glass Micro-Optics Heated by Carbide-Bonded Graphene Coating in Hot Embossing Process

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 363
Author(s):  
Lihua Li ◽  
Jian Zhou
Keyword(s):  
Residual Stress ◽  
Rapid Heating ◽  
Microlens Array ◽  
Hot Embossing ◽  
Heat Transfer Process ◽  
Trial And Error ◽  
Graphene Coating ◽  
Forming Temperature ◽  
Geometric Deviation

A newly developed hot embossing technique which uses the localized rapid heating of a thin carbide-bonded graphene (CBG) coating, greatly reduces the energy consumption and promotes the fabrication efficiency. However, because of the non-isothermal heat transfer process, significant geometric deviation and residual stress could be introduced. In this paper, we successfully facilitate the CBG-heating-based hot embossing into the fabrication of microlens array on inorganic glass N-BK7 substrate, where the forming temperature is as high as 800 °C. The embossed microlens array has high replication fidelity, but an obvious geometric warpage along the glass substrate also arises. Thermo-mechanical coupled finite element modelling of the embossing process is conducted and verified by the experimental results. Based on trial and error simulations, an appropriate compensation curvature is determined and adopted to modify the geometrical design of the silicon wafer mold. The warpage of the re-embossed microlens array is significantly decreased using the compensated mold, which demonstrates the feasibility of the simulation-oriented compensation scheme. Our work would contribute to improving the quality of optics embossed by this innovative CBG-heating-based hot embossing technique.

Analysis of Leveling Strategy for a Plate Mill

2010 ◽  
Vol 145 ◽  
pp. 424-428 ◽  
Author(s):  
Li Cui ◽  
Xian Lei Hu ◽  
Xiang Hua Liu
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Time Delay ◽  
Static Pressure ◽  
High Strength ◽  
Plate Mill ◽  
Elastic Plastic ◽  
Residual Curvature ◽  
Deformation Ratio

In order to analysis the effect of leveling strategy on the quality of plate products, the curvature integration by elastic-plastic differences was adopted to simulate leveling results by different leveling strategy. It had studied plastic deformation ratio, residual stress, residual curvature and leveling force for different leveling strategies to find the effectual strategy and the adaptability conditions were given. Additionally, static pressure leveling with the time delay strategy was analyzed, which was proved to be an effectual strategy to resolve the leveling problem for high strength thicker plate by a certain 3500mm mill plate.

Microscale Thermoplastic Forming of Bulk Metallic Glasses: Numerical Simulations and Experiments

2008 ◽  
Author(s):  
David L. Henann ◽  
Lallit Anand
Keyword(s):  
Numerical Simulation ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Processing Parameters ◽  
Hot Embossing ◽  
Simulation Tool ◽  
Processing Conditions ◽  
Trial And Error ◽  
Physical Experiments ◽  
Thermoplastic Forming

An extremely promising microscale processing method for bulk metallic glasses called thermoplastic forming has emerged in recent years. However, most of the recent experimental thermoplastic forming studies have been conducted by trial-and-error. In this paper, the large-deformation constitutive theory of Henann and Anand [1] is used as a numerical simulation tool for the design of micro-hot-embossing processes. This numerical simulation capability is used to determine appropriate processing parameters in order to carry out several successful micron-scale hot-embossing operation on the metallic glass Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vitreloy-1). By carrying out the corresponding physical experiments, it is demonstrated that microscale features in Vitreloy-1 may be accurately replicated under the processing conditions determined by use of the numerical simulation capability.

Research on some Key Mechanical Properties of Silicon Nitride Thin Films Deposited by PECVD

2015 ◽  
Vol 742 ◽  
pp. 773-777
Author(s):  
Qun Feng Yang ◽  
Jian Yi Zheng ◽  
Jun Qing Wang ◽  
Jun Hui Lin ◽  
Xue Nan Zhao ◽  
...  
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Residual Stress ◽  
Silicon Nitride ◽  
Mechanical Characteristics ◽  
Dielectric Films ◽  
Rotating Beam ◽  
Atomic Force ◽  
Scanning Electron

The purpose of this work is to study the mechanical characteristics of the silicon nitride(SiNx) thin films prepared by PECVD technique, some researches as follows were carried out. First, the SiNx thin films were deposited on the two different substrates. Then, the atomic force microscope (AFM) was adopted to test the surface quality of the SiNxfilms, and the scanning electron microscope (SEM) was used to test the section morphology of the SiNxthin films. Finally, the rotating beam structures was applied to measure the residual stress in the SiNx films. The SiNxthin films with low stress can be fabricated through PECVD, in which the surface roughness values(Ra) are 1.261 nm and 2.383nm, and the residual stress is 43.5 kPa. Therefore, the SiNxthin films deposited by PECVD are suitable for the preparation of device dielectric films in MEMS.

An Installation for Electrothermal Effects on a Workpiece

2020 ◽  
pp. 69-75
Author(s):  
S.B. Mariin ◽  
A.Y. Getopanov ◽  
W.A. Phyo ◽  
V.V. Grigoriev
Keyword(s):  
Residual Stress ◽  
Structural Strength ◽  
High Quality ◽  
Inductive Load ◽  
Positive Effects ◽  
Current Pulses ◽  
Electric Current Pulses ◽  
Three Phase ◽  
Electrothermal Effects

This paper presents a modernized installation for impacting a workpiece with electric current pulses whereby ensuring high quality of parts manufactured from titanium alloys. Electrical processes that occur when using a new method of switching an active-inductive load using a three-phase contactless thyristor starter are examined. The use of such a device can eliminate long transient processes during switching, improve control of the heating parameters of the workpiece and provide plasticization of the metal in short periods of time. Other positive effects of the three-phase contactless thyristor starter include the elimination of defects in the structure of the material, increase in the thermodynamic stability of the metals as well as in the structural strength and endurance, reduction of the anisotropy of the metals and the level of residual stress.

scholarly journals Application of graphene–polymer composite heaters in gas-assisted micro hot embossing

RSC Advances ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. 6336-6344 ◽  
Author(s):  
Cih Cheng ◽  
Kun-Cheng Ke ◽  
Sen-Yeu Yang
Keyword(s):  
Polymer Composite ◽  
Rapid Heating ◽  
Hot Embossing ◽  
Uniform Pressure ◽  
Polymeric Substrates

This paper reports a novel hot embossing technique using rapid heating and uniform pressure for replication of microstructures on polymeric substrates.

The Formation and Behaviour of Residual Stresses with Finished Surfaces

2016 ◽  
Vol 686 ◽  
pp. 63-67
Author(s):  
Frantisek Holešovsky ◽  
Radek Lattner ◽  
Martin Novák ◽  
Milan Dian
Keyword(s):  
Residual Stress ◽  
High Pressures ◽  
Load Capacity ◽  
Ground Surface ◽  
Plastic Deformations ◽  
Workpiece Surface ◽  
Dimension Stability ◽  
Machine Parts ◽  
Stress Influences

The single tool grains affect the workpiece surface during grinding in the separated areas of deformation. The elastic and consequently plastic deformations occur at the engagement of grains. The friction of grain and material likewise the friction of elementary chip and grain acts simultaneously. These phenomena are accompanied with an origination of great amount of heat and high pressures and that is the reason for residual stress origin and formation in the ground surface. The residual stress is an important factor in influencing usable properties of machine parts. The stress influences not only the dynamical load capacity of surface but the durability and quality of design units as well. This stress is considered as the source of so called technological notches, having an influence on corrosion resistance, wear resistance, and dimension stability of machine parts.

The Uniform Elongation of Web and Flange of H-Beam

2009 ◽  
Vol 79-82 ◽  
pp. 1919-1922 ◽  
Author(s):  
Jin Hong Ma ◽  
Wen Zhi Zhang ◽  
Wei Chen ◽  
Shen Bai Zheng ◽  
Hong Bin Li
Keyword(s):  
Residual Stress ◽  
Uniform Elongation ◽  
Rolling Process ◽  
Reduction Ratio ◽  
Elongation Ratio ◽  
Beam Production ◽  
Simulation And Experiment ◽  
H Beam ◽  
In Virtue Of

H-beam is widely used in the construction in virtue of its excellent sectional properties. Because of its complex section, flange and web are deformed in different zones in rolling process. The traditional elongation ratio between flange and web is 1.03~1.05, which obtained from experience. Web wave, crack, or flange crack, and the large residual stress exist in the H-beam production. The problems are mainly caused by the uneven elongation of flange and web. It is necessary to keep uniform elongation of flange and web to solve these problems. The modified reduction ratio between flange and web is provided in this paper. The ratios improve the quality of H-beam by simulation and experiment.

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