Using excimer lasers to clean CFRP prior to adhesive bonding

Fischer, Fabian; Kreling, Stefan; Gäbler, F.; Delmdahl, Ralph

doi:10.1016/s0034-3617(13)70156-5

Cited by 23 publications

(9 citation statements)

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“…These observations are consistent with the processes that were previously described in literature. 17,20 Especially 6 mm thick samples sporadically ignite before complete penetration. Under these conditions, irradiation takes longer compared to thinner samples.…”

Section: Resultsmentioning

confidence: 98%

“…For unidirectional lay-ups oval shaped damages are observed according to the preferred heat conduction in fiber direction. 20,34 The damaged area can be subdivided into the actual hole, the area of the incoming laser beam, where typically the resin matrix is ablated and delaminations are formed, and the surrounding heat-affected zone, where resin matrix might remain. The holes conically narrow from the front to the backside, what can be observed best in the additionally shown µ-CT images of virtual cross sections through the center of the panels including the holes (Figure 3).…”

Section: Resultsmentioning

confidence: 99%

“…The heat within the material is predominantly conducted along the fibers, as long as their heat conductivity is retained, 18,19 accompanied by degradation of the matrix and causing a decrease of the material’s mechanical properties, such as tensile, compression or shear stress. 20 The evaporation temperature of the matrix and the fiber differ by two orders of magnitude, causing the matrix to evaporate first. 21 This may result in stripping the matrix from the carbon fibers.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

High-energy laser effects on carbon fiber reinforced polymer composites with a focus on perforation time

Wolfrum

Eibl²,

Oeltjen

et al. 2021

Journal of Composite Materials

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Commercially available carbon fiber reinforced polymer matrix composite panels (Hexply® M18-1/G939 and 8552/IM7) with different thicknesses (1-6 mm) were exposed to continuous-wave high-energy laser radiation at various laser powers up to 10 kW under static conditions. The perforation times, the size of the damaged volume and the residual compressive strengths are determined and correlated to the irradiation parameters. It is found that for the time of perforation, the damaged volume, which is approximated by a cylinder shaped model, correlates linearly with the laser energy imposed onto the sample surface. This relationship can be used for a prediction of the perforation time for various laser powers, material thicknesses and laser spot diameters. Increasing laser energy results in a decay of residual compressive strength after impact. Visual inspection as well as micro-focused computed X-ray tomography and scanning electron microscopy indicate a small area of thermal damage outside the laser spot. Additionally, infrared spectroscopy characterizes incipient heat damage most sensitively.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High-energy laser effects on carbon fiber reinforced polymer composites with a focus on perforation time

Wolfrum

Eibl²,

Oeltjen

et al. 2021

Journal of Composite Materials

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show abstract

“…Most commonly employed mechanical methods such as abrading and blasting processes have major disadvantages such as fiber fracture, fiber matrix delamination and requirement of a secondary cleaning operation. Additionally, the use of peel‐plies for the preparation of CFRP surfaces is a popular technique in the aerospace industry; however, it has disadvantages of increasing manufacturing complexity and cost . Laser processing has the potential to overcome virtually all of these drawbacks and also offers advantages for the surface preparation of CFRP surfaces.…”

Section: Introductionmentioning

confidence: 99%

Laser surface treatment of CFRP composites for a better adhesive bonding owing to the mechanical interlocking mechanism

et al. 2019

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Adhesion can be greatly improved by the correct surface preparation techniques. One of the most common and useful technique is specific surface structuring which leads to mechanical interlocking and greater adhesion. This work describes the effect of laser-induced line pattern surface structuring on the mechanical interlocking mechanism and so on the adhesive bonding of carbon fiber reinforced polymer (CFRP) composites. Surface patterns with different laser scribes were obtained by CO 2 laser treatment. The effect of the number of a laser shot, the scribe depth, the number of the scribe and the angle between the direction of the laser scribes and mechanical test direction on the adhesive bonding strength of CFRP/CFRP joints was investigated by performing the single lap shear tests according to the ASTM D5868-01. After destructive tests, damaged surfaces were analyzed for determining the failure mechanisms. Mechanical tests showed that laser scribe characteristics especially the number of laser shot and the number of scribes have significant effects on the mechanical interlocking mechanism and so on the adhesion bonding strength. It is suggested that in order to improve the adhesion strength of CFRP/CFRP joints, mechanical interlocking mechanism shall be obtained by optimized laser scribe patterns. POLYM. COMPOS., 40:3611-3622, 2019.

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“…Laser surface treatment enables high precision processing that lends itself to automation and reproducibility for surface activation and removal of surface contaminants on CFRP surfaces. 3–14 By adjusting the laser parameters, it is possible to control the laser–solid interactions to remove surface contaminants and create texture on the surface without exposing or breaking the carbon fibers underneath the resin surface layer. This technique can also be used for other surfaces such as metal alloys and can be used to selectively remove surface layers such as paint or coatings without affecting the underlying substrate.…”

Section: Introductionmentioning

confidence: 99%

Correlation of Trace Silicone Contamination Analyses on Epoxy Composites Using X-ray Photoelectron Spectroscopy (XPS) and Laser-Induced Breakdown Spectroscopy (LIBS)

Ledesma

Palmieri

Campbell³

et al. 2018

Appl Spectrosc

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Surface treatment and surface characterization techniques are critical to ensure that adherends are chemically activated and free of contaminants before adhesive bonding. Silicone contamination from mold release agents and other sources can interfere with interfacial bonding, decreasing the durability and performance of bonded composite structures. It is necessary to have tools and methods that can be used in a production environment to reliably detect low levels of contaminants in a rapid, simple, and cost-effective manner to improve bond reliability. In this work, surface characterization of carbon fiber reinforced polymer (CFRP) composites with epoxy matrix was performed using laser-induced breakdown spectroscopy (LIBS), and the results were compared with those obtained from X-ray photoelectron spectroscopy (XPS). Laser-induced breakdown spectroscopy offers many advantages over XPS in terms of ease of use, sample preparation, and real-time results. The objective of the comparison was to study the sensitivity of LIBS and to investigate the quantification of the surface species measured by LIBS. Another objective was to assess the reliability of each technique for surface contaminant characterization. The as-processed CFRP panels had trace surface silicone contamination from the fabrication process, the source of which was not investigated. The composites were laser treated at select average laser power levels, resulting in varying levels of contamination reduction. The Si atomic percentage measurements using XPS were conducted on both control and laser-ablated surfaces. The results showed an excellent correlation in Si concentration between the two techniques.

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Using excimer lasers to clean CFRP prior to adhesive bonding

Cited by 23 publications

References 0 publications

High-energy laser effects on carbon fiber reinforced polymer composites with a focus on perforation time

High-energy laser effects on carbon fiber reinforced polymer composites with a focus on perforation time

Laser surface treatment of CFRP composites for a better adhesive bonding owing to the mechanical interlocking mechanism

Correlation of Trace Silicone Contamination Analyses on Epoxy Composites Using X-ray Photoelectron Spectroscopy (XPS) and Laser-Induced Breakdown Spectroscopy (LIBS)

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