Preparation of electrodes on CFRP composites with low contact resistance comprising laser-based surface pre-treatment

Patent metadata

Field	Value
Publication number	US-10722984-B2
Application number	US-201615576586-A
Country	US
Kind code	B2
Filing date	Jun 24, 2016
Priority date	Jun 25, 2015
Publication date	Jul 28, 2020
Grant date	Jul 28, 2020

Abstract

Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a method includes preparing a pretreated target area on a CFRP composite surface using laser pulsed irradiation and bonding an electrode to exposed fibers in the pretreated target area. The surface preparation can allow the electrode to have a low contact resistance with the CFRP composite.

First claim

Therefore, at least the following is claimed:

1. A method for bonding an electrode to a carbon fiber reinforced polymer (CFRP), the method comprising:
selecting an average power P ave and a scanning speed v of a laser system;
preparing a pretreated target area on the carbon fiber reinforced polymer (CFRP) composite surface by using laser pulsed irradiation from the laser system so that at least 75% of carbon fibers of the CFRP composite are exposed;
forming an electrode directly to the exposed carbon fibers in the pretreated target area; and
bonding lead wires to the electrode with a conductive epoxy adhesive,
wherein the average power P ave and the scanning speed v of the laser system are selected to achieve the at least 75% exposed carbon fibers.

2. The method of claim 1 , wherein the electrode includes a silver paste and a copper layer.

3. The method of claim 1 , wherein the electrode has a contact resistance of 0.1 ohms or less.

4. The method of claim 1 , wherein the electrode exhibits a uniform bonding over the pretreated target area.

5. The method of claim 1 , comprising:
preparing a plurality of pretreatment target areas on the CFRP composite surface using laser pulsed irradiation; and
bonding a plurality of electrodes to corresponding ones of the plurality of pretreatment target areas.

6. The method of claim 1 , wherein the at least 75% exposed carbon fibers in the pretreated target area of the CRFP composite are fully exposed by the laser pulsed irradiation.

7. The method of claim 6 , wherein exposure of the carbon fibers is evaluated using Raman mapping of the pretreated target area.

8. The method of claim 1 , wherein the electrode is mechanically interlocked with fully exposed fibers in the pretreated target area during bonding.

9. The method of claim 1 , wherein forming the electrode comprises applying silver paste to the pretreated target area.

10. A method for monitoring a structural health of a carbon fiber reinforced polymer (CFRP) composite, the method comprising:
positioning the CFRP composite for pretreatment of a target area of a CFRP surface;
selecting an average power P ave and a scanning speed v of a laser system;
preparing the pretreated target area by irradiation with a pulsed laser beam along a series of paths in the target area, wherein the pulsed laser beam is generated by the laser system so that at least 75% of carbon fibers of the CFRP composite are exposed; and
forming an array of electrodes directly to the exposed carbon fibers in the pretreated target area;
measuring associated impedances of the array of electrodes at a domain boundary of a given domain of the CFRP composite; and
reconstructing the given domain based on the measured impedances using a computed tomographic technique, for monitoring the structural health of the CFRP composite,
wherein the average power P ave and the scanning speed v of the laser system are selected to achieve the at least 75% exposed carbon fibers.

11. The method of claim 10 , wherein the series of paths are a plurality of parallel paths.

12. The method of claim 10 , wherein the pulsed laser beam has a focused beam diameter (d s ) of 25 μm on the CFRP surface.

13. The method of claim 10 , wherein the series of paths have a minimum line spacing (p) of 30 μm.

14. The method of claim 10 , wherein the pulsed laser beam has a frequency (f) of 30 kHz and traverses the series of paths at the scanning speed (v) of less than or equal to 500 mm/second, and with the average power (P ave ) being less than or equal to 30 Watts.

15. The method of claim 14 , wherein the scanning speed (v) is less than 100 mm/second and the average power (P ave ) of the laser is equal to or less than 7.5 Watts.

16. The method of claim 14 , wherein the scanning speed (v) is equal to or greater than 50 mm/second and the average power (P ave ) of the laser is greater than 4.5 Watts.

17. The method of claim 16 , wherein the average power (P ave ) of the laser is greater than 6.75 Watts when the scanning speed (v) is greater than 75 mm/second and the average power (P ave ) of the laser is equal to or less than 6.75 Watts when the scanning speed (v) is equal to or less than 75 mm/second.

18. The method of claim 16 , wherein the average power (P ave ) of the laser is greater than 5.25 Watts when the scanning speed (v) is equal to or greater than 60 mm/second.

19. The method of claim 10 , wherein a pulse duration (τ p ) of the pulsed laser is greater or equal to 10 nanoseconds.

Assignees

• Univ King Abdullah Sci & Tech
• Saudi Arabian Oil Co
• Saudi Arabian Oil Company Aramco R&D

Inventors

• Almuhammadi Khaled Hamdan
• Lubineau Gilles Henri Fernand
• Alfano Marco Francesco
• Buttner Ulrich

Classifications

• G01N27/026 Primary

  Dielectric impedance spectroscopy (electrochemical impedance spectroscopy for measuring corrosion G01N17/02) · CPC title

• G01N27/041

  of a solid body · CPC title

• G01N2001/045

  Laser ablation; Microwave vaporisation · CPC title

• B23K26/352

  for surface treatment · CPC title

• G01N1/44

  Sample treatment involving radiation, e.g. heat · CPC title