Stripping of PFA Fluoropolymer Coatings Using a Nd:YAG Laser (Q-Switch) and an Yb Fiber Laser (CW).

Guillermo Guerrero-Vaca,Esther Molero,Jon Lambarri,Óscar Rodríguez-Alabanda,Carlos Soriano,Pablo E Romero

doi:10.3390/polym11111738

Guillermo Guerrero-Vaca, Esther Molero + Show 4 more

Open Access

https://doi.org/10.3390/polym11111738

Copy DOI

Journal: Polymers	Publication Date: Oct 24, 2019
Citations: 8	License type: CC BY 4.0

Affiliation: University of Córdoba, Tekniker

Abstract

Fluoropolymers such as PFA are used as coatings for the protection of metal substrates due to their high chemical inertia and non-stick properties. These are “wear and tear” coatings and they degrade, at which point they should be removed for a new application. The removal of these types of coating by laser is of interest due to the process’s flexibility, precision, ease of automation, and environmental sustainability. The efficiency of the procedure was shown with the use of a source in a pulsed Nd:YAG and a source in continuous mode of fiber (Yb). The rates of stripping (cm2/min) and fluence (J/cm2) were analyzed and related to the power of the laser sources. Variations of the substrate after stripping were studied: roughness and hardness. The properties of the coating, thickness, roughness, water sliding angle, and microhardness were also evaluated. It was concluded that the laser in continuous mode was more efficient than the pulsed laser; laser removal of fluoropolymers has a strong relationship with reflectivity, and the mechanical and surface properties of the substrate after stripping remained virtually unchanged.

Highlights

One of them is the sustainability of the process from an environmental point of view [12], due to the fact that the use of potentially toxic and polluting organic solvents, such as those used in techniques based on chemical removal, is eliminated
Residues, or oxides to be removed are affected while the laser ablation stops at the substrate due to reflection on the metal surface
The Quanta laser source (Q-switch), which works with nanosecond pulses, produced the stripping of the perfluoro alkoxy alkoxy alkane (PFA) coating by photomechanical effect

Summary

Introduction

The laser radiation cleaning process has become a solid alternative to the more traditional methods of thermal, mechanical, and chemical nature in a wide range of materials and applications, such as removal of polymeric coatings [1,2,3,4,5]; cleaning of art works [6], antiquities, and buildings [7,8]; nuclear and biological decontamination [9]; mold cleaning [10]; and particle removal in the microelectronics and optics industries [11].The advantages over current technologies include, in addition to those typically applicable to all laser processes (precision, flexibility, ease of automation), two main important aspects. The laser radiation cleaning process has become a solid alternative to the more traditional methods of thermal, mechanical, and chemical nature in a wide range of materials and applications, such as removal of polymeric coatings [1,2,3,4,5]; cleaning of art works [6], antiquities, and buildings [7,8]; nuclear and biological decontamination [9]; mold cleaning [10]; and particle removal in the microelectronics and optics industries [11]. Residues, or oxides to be removed are affected while the laser ablation stops at the substrate due to reflection on the metal surface. The power density of the laser beam can be adjusted to achieve the desired result. This is an important advantage compared to other conventional methods

Methods

Results

Discussion

Conclusion