Continuous processing of pre-pregs using radio frequency heating

Vashisth, Aniruddh; Healey, Reagan E.; Pospisil, Martin J.; Oh, Ju Hyun; Green, Micah J.

doi:10.1016/j.compscitech.2020.108211

Cited by 27 publications

(28 citation statements)

References 26 publications

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“…Heating and partially/fully curing carbon ber composites is an excellent example of RF rapid volumetric heating; heating composites in conventional ovens and autoclaves takes signicant time (10-30 minutes) whereas using RF elds CF/epoxy systems can be heated as fast as 70 C s À1 to attain curing temperatures within 2 minutes of the cure-cycle. 25 (3) Targeted heating: in assemblies that require heating on specic locations, RF elds can provide targeted heating for applications such as bonding. This method bypasses the need to heat the whole assembly, potentially leading to residual thermal stresses in the assembly once it cools down.…”

Section: Benefits Of Dielectric Heatingmentioning

confidence: 99%

“…30 Also heating rates of carbon ber composites jump from 10 C s À1 to 70 C s À1 when input power is increased from 5 W to 25 W keeping a xed frequency of 66 MHz. 25 (6) Low infrastructure: in terms of instrument footprint, dielectric heating has reduced production oor-space requirements. For example, typical composite autoclaves are cylindrical in shape and the smallest of these structures have 4 0 inner diameters and are 6 0 long plus the control systems; whereas RF heating systems consist of an RF amplier and signal generator, the size of the RF applicator can be tailored according to requirements.…”

Section: Benefits Of Dielectric Heatingmentioning

confidence: 99%

“…4). 25,[35][36][37] RF elds have successfully shown composite processing capabilities such as curing of carbon ber (CF) reinforced thermosetting composites and out-of-oven ceramic manufacturing using multiple susceptors. Thermosetting prepregs are fabricated continuously by using energy-expensive methods such as large convection ovens, or infra-red lamps.…”

Section: Volumetric Heatingmentioning

confidence: 99%

“…4 Volumetric RF heating has successfully shown application in (counterclockwise, from top-right) ceramics and carbon fiber composite fabrication, catalytic reactors, thermally driven chemical reactions, and medical applications. 25,[35][36][37] Nanoscale Adv. CNT circuits ten times faster than conventional methods, identifying faulty circuits more reliably.…”

Section: Minireview Nanoscale Advancesmentioning

confidence: 99%

“…14,15 Recently, researchers found that RF elds between 1-200 MHz can be used to heat carbonaceous materials including CNTs, 22 carbon black, 23 graphene, 24 and carbon bers. 25 The ability to use lower frequencies rather than microwaves for heating materials offers key benets. These include greater penetration depths than microwaves, which allows for better heating in thicker materials.…”

Section: Introductionmentioning

confidence: 99%

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Radio frequency heating and material processing using carbon susceptors

et al. 2021

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Section: Benefits Of Dielectric Heatingmentioning

confidence: 99%

Section: Benefits Of Dielectric Heatingmentioning

confidence: 99%

Section: Volumetric Heatingmentioning

confidence: 99%

Section: Minireview Nanoscale Advancesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Radio frequency heating and material processing using carbon susceptors

et al. 2021

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Using Radio‐Frequency Fields for Local Heating and Curing of Adhesive for Bonding Metals

et al. 2021

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Lightweighting of metal structures can be achieved by replacing metallic fasteners with thermosetting adhesives. However, thermal curing of adhesives to bond metals in an oven can lead to distortions due to mismatched coefficients of thermal expansion, thereby compromising the structural integrity. Targeted heating of the adhesive can be utilized to minimize distortions and residual stresses in metal‐composite assembly. Herein, it is shown that rapid heating of carbon nanoparticles in the presence of radio‐frequency (RF) electromagnetic fields can be used to cure nanocomposite adhesives for bonding metal substrates selectively. Using the metal components of a structure as a part of an RF circuit, electric fields are generated through a carbon‐nanofiller loaded adhesive, which then volumetrically heats and cures. Comparable lap‐shear strengths and adhesive peel resistance are measured for RF‐ and oven‐cured composites. RF‐cured multimaterial bonding specimens (aluminum‐to‐steel) show minimal distortion, resulting in ≈590% higher fracture energies in peel mode as compared with oven‐cured specimens.

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Rapid Manufacturing via Selective Radio‐Frequency Heating and Curing of Thermosetting Resins

Sarmah¹,

Desai²,

Tezel

et al. 2022

Adv Eng Mater

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Thermosetting polymers are stable, high-performance materials that are crosslinked by heating and curing at a specified temperature. These materials are mechanically strong and highly resistant to thermal and chemical degradation, such that thermoset composites are a popular choice for applications ranging from battery frameworks to aerospace and automotive frames. [1] Current manufacturing processes for thermosetting epoxy resins include molding and curing of the matrix in a hightemperature oven, which is energy, labor, and time consuming, and sets limits on achievable part geometries and process times. [2,3] Existing methodologies to form epoxy composites include stacking one layer over the other to make 3D parts. [4] The ability to 3D print these multilayered structures would allow for the free-form fabrication of complex geometries, eliminating the additional cost of ovens and specific molds for each part. Additive manufacturing has been extensively used to 3D print thermoplastics [5][6][7] and metals. [8][9][10] A development of such an on-demand, rapid production technique could facilitate a distributed manufacturing economy for high-performance composites. [11] There has been limited research in the field of printing thermosets from a reservoir of resin. Selective curing of photocurable resins on the upper interface of liquid reservoirs using UV light has been reported previously to print 3D structures. [12,13] The materials used to make structures using this method are at least partially made of UV curable resins rather than conventional commercial thermosets. Apart from this, a handful of technologies have been developed for the additive manufacturing of thermosets. Extrusion-based printing of thermosets has been made possible by printing inside a thixotropic support bath, followed by extraction from the bath and curing in an oven. [14] Other studies have shown that direct ink writing coupled with UV-assisted curing can be used to 3D print light-sensitive resins. [15,16] Studies have also added viscosity-modifying agents to make the resin shearthinning. This allows the resin to be printed via direct ink writing such that it can retain its shape after being extruded, before being transferred to an oven for curing. [17][18][19] Additive manufacturing of thermosets via frontal polymerization has been explored to print complex shapes but is restricted by the limited number of resin chemistries that can be printed using this method. [20,21] It is highly desirable to develop an out-of-oven curing methodology that would allow for selective curing and 3D printing of

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Continuous processing of pre-pregs using radio frequency heating

Cited by 27 publications

References 26 publications

Radio frequency heating and material processing using carbon susceptors

Radio frequency heating and material processing using carbon susceptors

Using Radio‐Frequency Fields for Local Heating and Curing of Adhesive for Bonding Metals

Rapid Manufacturing via Selective Radio‐Frequency Heating and Curing of Thermosetting Resins

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