Evaluation of Substrates of Al-Mg and Aluminized Steel Coated With Non-Stick Fluoropolymers after the Removal of the Coating

Rodríguez‐Alabanda, Óscar; Romero, Pablo E.; Guerrero‐Vaca, Guillermo

doi:10.3390/ma11112309

Cited by 4 publications

(6 citation statements)

References 32 publications

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“…As far as to the mechanical properties of the substrate are concerned, the Vickers hardness was studied. It is known that due to the curing of the PFA coating in the PFA sintering process, an annealing of the substrate and a notable decrease in hardness occurs [20,21,44]. The decrease was evaluated and is between 13.8–14.6% with respect to the state of supply.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2019

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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.

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Section: Discussionmentioning

confidence: 99%

“…They are commonly used as protection inside chemical reactors [19], in metal parts for the demolding of food dough, and particularly in trays and molds for the baking industry. [20]. The removal of these coatings is complex due to their high adhesion to the substrate and high resistance to relatively elevated temperatures (400 °C).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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“…Hardness increases have reached levels of 17-19 units of HV5. In the case of the two-step procedure, the substrate does not experience any improvement in hardness with respect to the state after the application of PTFE [8,32]. Figure 7 shows the images obtained by the high-resolution scanning electron microscope in the state of supply and after stripping with each type of abrasive.…”

Section: Hardness Of Substratesmentioning

confidence: 99%

Experimental Study for the Stripping of PTFE Coatings on Al-Mg Substrates Using Dry Abrasive Materials

et al. 2020

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Polytetrafluoroethylene (PTFE) coatings are used in many applications and processing industries. With their use, they wear out and lose properties and must be replaced by new ones if the cost of the element so advises. There are different stripping techniques, but almost all of them are very difficult and require strict environmental controls. It is a challenge to approach the process through efficient and more sustainable techniques. In the present work, we have studied the stripping of PTFE coatings by projection with abrasives (1 step) as an alternative to carbonization + sandblasting procedures (2 steps). For this purpose, different types of abrasives have been selected: brown corundum, white corundum, glass microspheres, plastic particles, and a walnut shell. The tests were performed at pressures from 0.4 to 0.6 MPa on PTFE-coated aluminium substrates of EN AW-5182 H111 alloy. Stripping rates, surface roughness, and substrate hardness have been studied. Scanning electron microscopy (SEM) images of sandblasted specimens have also been obtained. All abrasives improved mechanical and surface properties in one-step vs. two-step processes. The abrasives of plastic and glass microspheres are the most appropriate for the one-step process, which increases the hardness and roughness level Ra in the substrate. Corundum abrasives enable the highest stripping rates.

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“…We used the brown corundum RBT9 Gr.60 (MPA, Cornellá, Barcelona, Spain). Higher pressures or longer blasting times were avoided to minimize damage of the AS samples [1]. The textured samples were carefully cleaned by sonication in acetone for 5 min and, afterwards, in ethanol for 5 min.…”

Section: Surface Preparationmentioning

confidence: 99%

“…Release/demolding coatings are typically prepared for food, doughs, liquids, gels, and foams. Aluminium-magnesium (Al-Mg) alloy and aluminized steel (AS) substrates are used in industry to produce trays, utensils, and molds for baking ovens [1]. However, these metallic materials are sticky and hydrophilic.…”

Section: Introductionmentioning

confidence: 99%

Superhydrophobic Cerium-Based Coatings on Al-Mg Alloys and Aluminized Steel

et al. 2019

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Aluminum-magnesium (Al-Mg) alloy and aluminum-coated steel (aluminized steel) are typically used for the manufacturing of baking trays and molds. For these applications, these materials must be modified to develop release and hydrophobic properties. With this aim, the bare substrates are typically coated with low-surface energy materials such as fluoropolymers, elastomers, or sol-gel layers. In this work, some alternative strategies to prepare these functional surfaces are presented. We used three-step processes involving (i) micro-texturing, (ii) nano layer deposition through immersion and electrodeposition, and (iii) hydrophobization. The raw substrates were sanded or sandblasted at the micro scale, accordingly. Texturization at the nano scale was achieved with a cerium layer formed by electrodeposition or solution immersion. The cerium layers were hydrophobized with fatty acids. The wetting properties of the samples were studied with tilting-plate and bouncing drop methods. We measured the surface roughness of the samples by contact profiling and analyzed their surface morphology using a field emission scanning electron microscope (FESEM). The elemental chemical composition of the samples was analyzed by energy-dispersive X-ray spectroscopy (EDX). The wettability results indicated that the best performance for the Al-Mg substrates was reached by sandblasting and later immersion in a cerium nitrate solution. For aluminized steel substrates, the best results were obtained with both electrodeposition and immersion methods using a cerium chloride solution.

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Evaluation of Substrates of Al-Mg and Aluminized Steel Coated With Non-Stick Fluoropolymers after the Removal of the Coating

Cited by 4 publications

References 32 publications

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

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

Experimental Study for the Stripping of PTFE Coatings on Al-Mg Substrates Using Dry Abrasive Materials

Superhydrophobic Cerium-Based Coatings on Al-Mg Alloys and Aluminized Steel

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