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Li L, Wang R, Huang Y, Li X. Modeling and Experiments on Temperature and Electrical Conductivity Characteristics in High-Temperature Heating of Carbide-Bonded Graphene Coating on Silicon. MICROMACHINES 2024; 15:673. [PMID: 38930643 PMCID: PMC11206079 DOI: 10.3390/mi15060673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/12/2024] [Accepted: 05/16/2024] [Indexed: 06/28/2024]
Abstract
A novel non-isothermal glass hot embossing system utilizes a silicon mold core coated with a three-dimensional carbide-bonded graphene (CBG) coating, which acts as a thin-film resistance heater. The temperature of the system significantly influences the electrical conductivity properties of silicon with a CBG coating. Through simulations and experiments, it has been established that the electrical conductivity of silicon with a CBG coating gradually increases at lower temperatures and rapidly rises as the temperature further increases. The CBG coating predominantly affects electrical conductivity until 400 °C, after which silicon becomes the dominant factor. Furthermore, the dimensions of CBG-coated silicon and the reduction of CBG coating also affect the rate and outcome of conductivity changes. These findings provide valuable insights for detecting CBG-coated silicon during the embossing process, improving efficiency, and predicting the mold core's service life, thus enhancing the accuracy of optical lens production.
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Affiliation(s)
- Lihua Li
- Sino-German College of Intelligent Manufacturing, Shenzhen Technology University, Shenzhen 518118, China; (R.W.)
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The Interface Thermal Resistance Evolution between Carbide-Bonded Graphene Coating and Polymer in Rapid Molding for Microlens Array. Polymers (Basel) 2021; 13:polym13142334. [PMID: 34301091 PMCID: PMC8309634 DOI: 10.3390/polym13142334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 07/10/2021] [Accepted: 07/12/2021] [Indexed: 11/17/2022] Open
Abstract
Surface rapid heating process is an efficient and green method for large-volume production of polymer optics by adopting 3D graphene network coated silicon molds with high thermal conductivity. Nevertheless, the heat transfer mechanism including the interface thermal resistance evolution between 3D graphene network coating and polymer has not been thoroughly revealed. In this study, the interface thermal resistance model was established by simplifying the contact situation between the coating and polymethylmethacrylate (PMMA), and then embedding into the finite element method (FEM) model to study the temperature variations of PMMA in surface rapid heating process. Heating experiments for graphene network were then carried out under different currents to provide the initial heat for heat transfer model. In addition, residual stress of the PMMA lens undergoing the non-uniform thermal history during molding was presented by the simulation model together. Finally, the optimal molding parameters including heating time and pressure will be determined according to calculation results of the interface thermal resistance model and microlens array molding experiment was conducted to illustrate that the interface thermal resistance model can predict the temperature of the polymer to achieve a better filling of microlens array with smooth surface and satisfactory optical performance.
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Evaluation of Warpage and Residual Stress of Precision Glass Micro-Optics Heated by Carbide-Bonded Graphene Coating in Hot Embossing Process. NANOMATERIALS 2021; 11:nano11020363. [PMID: 33535579 PMCID: PMC7912754 DOI: 10.3390/nano11020363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 11/23/2022]
Abstract
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.
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Zhang L, Pan J, Cabrera ED, Garman PD, Wu M, Li Y, Zhang D, Yu J, Yi AY, Castro J, Lee LJ. Highly Oriented Graphitic Networks Grown by Chemical Vapor Deposition as Thermal Interface Materials. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c04519] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lin Zhang
- Department of Mechanical Engineering, Keio University, Yokohama 223-8522, Japan
| | - Junjie Pan
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Eusebio D. Cabrera
- Nanomaterial Innovation Ltd., 1109 Millcreek Lane, Columbus, Ohio 43220, United States
| | - Paul D. Garman
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Min Wu
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Yifan Li
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Dan Zhang
- Department of Integrated Systems Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Jianfeng Yu
- Nanomaterial Innovation Ltd., 1109 Millcreek Lane, Columbus, Ohio 43220, United States
| | - Allen Y. Yi
- Department of Integrated Systems Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Jose Castro
- Department of Integrated Systems Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - L James Lee
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, United States
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Liu X, Zhang L, Zhou W, Zhou T, Yu J, Lee LJ, Yi AY. Fabrication of Plano-Concave Plastic Lens by Novel Injection Molding Using Carbide-Bonded Graphene-Coated Silica Molds. JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING 2019; 141:081011. [PMID: 32728336 PMCID: PMC7388655 DOI: 10.1115/1.4043980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Injection molding of plastic optical lenses prevails over many other techniques in both efficiency and cost, however polymer shrinkage during cooling, high level of uneven residual stresses and refractive index variations have limited its potential use for high precision lenses fabrication. In this research, we adopted a newly-developed strong graphene network to both plain and convex fused silica mold surfaces and proposed a novel injection molding of plano-concave lenses with graphene coated fused silica molds. The unique combination of the graphene coating and fused silica substrate maximize the mechanical properties of the mold and coating materials, namely high hardness, low surface friction, and high heat preservation effect during cooling since fused silica has low thermal conductivity. This advanced injection molding process was implemented in molding of plano-concave lenses resulting in reduced polymer shrinkage. In addition, internal residual stresses, and refractive index variations were also analyzed and discussed in detail. Meanwhile, as a comparison of conventional injection mold material, aluminum mold inserts with the same shape and size were also diamond machined and then employed to mold the same plano-concave lenses. Finally, a simulation model using Moldex3D was utilized to interpret stress distributions of both graphene and aluminum molds and then validated by experiments. The comparison between graphene and aluminum molds reveals that the novel injection molding with carbide-bonded graphene coated fused silica mold inserts is capable of molding high quality optical lenses with much less shrinkage and residual stresses, but more uniform refractive index distribution.
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Affiliation(s)
- Xiaohua Liu
- School of Mechanical Engineering, Beijing Institute of Technology, No.5 Zhongguancun South Street, Haidian District, Beijing 100081, P.R. China
- Department of Integrated Systems Engineering, The Ohio State University, Columbus, Ohio 43210, USA
| | - Lin Zhang
- Department of Integrated Systems Engineering, The Ohio State University, Columbus, Ohio 43210, USA
| | - Wenchen Zhou
- Department of Integrated Systems Engineering, The Ohio State University, Columbus, Ohio 43210, USA
| | - Tianfeng Zhou
- School of Mechanical Engineering, Beijing Institute of Technology, No.5 Zhongguancun South Street, Haidian District, Beijing 100081, P.R. China
| | - Jianfeng Yu
- Nanomaterial Innovation Ltd., 1109 Millcreek Lane, Columbus, Ohio 43220-4949, USA
| | - L. James Lee
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, USA
| | - Allen Y. Yi
- Department of Integrated Systems Engineering, The Ohio State University, Columbus, Ohio 43210, USA
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Li L, Chan MK, Lee WB, Ng MC, Chan KL. Modeling and experimental performance analysis of a novel heating system and its application to glass hot embossing technology. OPTICS LETTERS 2019; 44:3454-3457. [PMID: 31305546 DOI: 10.1364/ol.44.003454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Traditional glass molding involves infrared heating; however, the thermal cycle time is long. A molding technique based on three-dimensional carbide-bonded graphene (CBG) has been developed to mold boron silicon glass. This CBG coating on a wafer silicon die can serve as a thin-film resistance heater to heat up the sample surface very rapidly with a relatively low applied voltage. To improve the precision temperature control in hot embossing so as to enhance the process quality, a heating system with lower energy consumption, shorter cycle time, and much more precision control is proposed. We have used COMSOL to simulate the whole heating process, and the heating behavior of a CBG-coated silicon wafer was experimentally investigated. The results showed that the repeatability of the heating system is stable, and it is suitable for precision glass hot embossing. Finally, an example of a precisely fabricated microlens array (Schott P-SK57) is embossed by using this novel heating system.
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Zhang L, Zhou W, Yi AY. Rapid localized heating of graphene coating on a silicon mold by induction for precision molding of polymer optics. OPTICS LETTERS 2017; 42:1369-1372. [PMID: 28362771 DOI: 10.1364/ol.42.001369] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In compression molding of polymer optical components with micro/nanoscale surface features, rapid heating of the mold surface is critical for the implementation of this technology for large-scale applications. In this Letter, a novel method of a localized rapid heating process is reported. This process is based on induction heating of a thin conductive coating deposited on a silicon mold. Since the graphene coating is very thin (∼45 nm), a high heating rate of 10∼20°C/s can be achieved by employing a 1200 W 30 kHz electrical power unit. Under this condition, the graphene-coated surface and the polymer substrate can be heated above the polymer's glass transition temperature within 30 s and subsequently cooled down to room temperature within several tens of seconds after molding, resulting in an overall thermal cycle of about 3 min or shorter. The feasibility of this process was validated by fabrication of optical gratings, micropillar matrices, and microlens arrays on polymethylmethacrylate (PMMA) substrates with very high precision. The uniformity and surface geometries of the replicated optical elements are evaluated using an optical profilometer, a diffraction test setup, and a Shack-Hartmann wavefront sensor built with a molded PMMA microlens array. Compared with the conventional bulk heating molding process, this novel rapid localized induction heating process could improve replication efficiency with better geometrical fidelity.
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Cabrera ED, Zhang P, Liao WC, Yen YC, Yu J, Castro J, Lee LJ. Graphene coating assisted injection molding of ultra-thin thermoplastics. POLYM ENG SCI 2015. [DOI: 10.1002/pen.24079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Eusebio Duarte Cabrera
- Department of Integrated Systems Engineering; The Ohio State University; Columbus Ohio 43210
| | - Panpan Zhang
- Department of Chemical and Biomolecular Engineering; The Ohio State University; Columbus Ohio 43210
| | - Wei-Ching Liao
- Department of Chemical and Biomolecular Engineering; The Ohio State University; Columbus Ohio 43210
| | - Ying-Chieh Yen
- Department of Chemical and Biomolecular Engineering; The Ohio State University; Columbus Ohio 43210
| | - Jiangfeng Yu
- Nanomaterial Innovation Ltd (NIL); 1971 Neil Ave. Columbus Ohio 43210
| | - Jose Castro
- Department of Integrated Systems Engineering; The Ohio State University; Columbus Ohio 43210
| | - L. James Lee
- Department of Chemical and Biomolecular Engineering; The Ohio State University; Columbus Ohio 43210
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