Paint Removal Process Research Articles

Comparative study of infrared nanosecond laser surface paint removal for carbon fiber reinforced polymer and glass fiber reinforced polymer

Carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) are widely used in aerospace applications due to their excellent properties. Green and efficient laser cleaning technology has a broad development prospect in the paint removal treatment of aerospace composites. However, the lack of theoretical analysis and guidance has prevented the industrial application of laser paint removal technology. An infrared nanosecond laser is used to clean the paint layer on the surface of CFRP and GFRP, and the best paint removal process parameters are explored. Surface micromorphology and 3D morphology of CFRP and GFRP after cleaning are observed to reveal the cleaning quality. The FTIR spectrum is used to verify the cleanliness of the paint layer. In addition, the contact angle and bonding force are tested, and the experimental results show that the surface wettability of both surfaces is enhanced after cleaning, and the paint adhesion of both surfaces is improved after repainting. Temperature monitoring, acoustic signal monitoring and high-speed photography monitoring are used to monitor the two cleaning processes respectively. The temperature, amplitude intensity, and plasma size of the two in the cleaning process are compared and analyzed. Based on the monitoring results, it is found that the cleaning mechanism of fiber-reinforced composites includes thermal ablation, vibration effect and plasma impact effect.

Simulation and Experimental Study on Continuous Wave Fiber Laser Removal of Epoxy Resin Paint Film on the Surface of 6061 Aluminum Alloy

Paint removal is an essential process in the industrial field. Laser technology provides an effective method of paint removal to replace traditional mechanical and chemical methods. This paper establishes a continuous wave (CW) laser thermal paint removal model based on heat conduction theory and Arrhenius’ law. The paint stripping process of epoxy paint film on the surface of 6061 aluminum alloy via CW laser was studied through simulation and experiment. We found that the carbonization of the paint film during the CW laser paint removal process will inhibit the laser paint removal process. Therefore, the paint removal efficiency of the CW laser is limited. The depth of CW laser paint removal increases linearly with the CW laser power density. However, during the CW laser paint removal process, due to the pyrolysis of the paint film and the reflection of the laser by the substrate, the surface temperature of the material first increases and then decreases. In addition, after laser paint removal, the surface roughness of the material after paint removal is reduced due to the melting of the base material. The model established in this article can provide a theoretical reference for studying the CW laser paint removal process.

Evolution and interpretation of LIBS signals based on laser selective layered paint removal from aircraft composite tail

The reliability and controllability of laser selective layered paint removal depend on effective online monitoring technology. In the process of laser cleaning the surface paint layer of the aircraft composite tail, this paper studied the evolution and interpretation of laser induced breakdown spectroscopy (LIBS) signals. The laser power is adjusted to achieve different depths of the laser cleaned composite surface paint layer to compare the Pearson linear correlation between the LIBS online spectrum and the reference spectrum and decode the characteristic peak signal of the LIBS spectrum. The linear correlation of the LIBS spectra and the evolution of the characteristic peaks of the LIBS spectra are mutually verified to establish the intrinsic correlation between the controllability of layered paint removal and the variation of the LIBS spectra, which demonstrates the feasibility of the LIBS technology for online monitoring and feedback of laser paint removal. The results show that the Pearson correlation coefficient r was 0.87–0.89 for the laser cleaning depth range of 44.79–51.50 μm, the layered boundary of laser cleaning the topcoat without damaging the primer is reached, it is proved that the Pearson correlation coefficient r can determine the laser paint removal process. This research compared the different LIBS spectra with cleaning depths at 44.79 and 51.50 μm. It was found that the characteristic peak of strontium element Sr I at wavelength 460.66 nm could characterize the delamination boundary of laser paint removal from aircraft composite tail.

Investigation of paint removal by atmospheric pressure plasma jet

Acrylic polyurethane paint on the surface of 2A12 Al alloy was cleaned utilizing an atmospheric pressure plasma jet in this work. The dynamic evolution of the paint removal process during plasma treatment with time was explored through analysis of morphology and chemical states. The results showed that although the thickness of paint could be reduced effectively with an increase in cleaning time, the removal rate of paint gradually decreased with time. During the initial cleaning process range, its original smooth morphology of paint turned rugged quickly and was almost unchanged with further plasma treatment. Element and chemical state analysis showed that the content of C in the paint layer decreased obviously after plasma treatment. In contrast, the O content increased remarkably. The cleaning mechanism could be mainly attributed to the reaction between active O-containing species in air plasma and organic components in the paint. After removal of superficial organic matter, residue inorganic metal oxide substances aggregated on the base. The exposed metal oxides on the one hand elevated the superficial O content, but on the other hand hindered further plasma penetration, resulting in a gradual decrease in cleaning rate with cleaning time. Therefore, physical wiping was proposed to be incorporated with the plasma method and effective removal of paint was realized.

Real-time LIBS monitoring of laser-based layered controlled paint removal from aircraft skin based on random forest.

Laser-induced breakdown spectroscopy (LIBS) is expected to be used for real-time monitoring and closed-loop control of laser-based layered controlled paint removal (LLCPR) from aircraft skin. However, the LIBS spectrum must be rapidly and accurately analyzed, and the monitoring criteria should be established based on machine learning algorithms. Hence, this study develops a self-built LIBS monitoring platform for the paint removal process utilizing a high-frequency (kilohertz-level) nanosecond infrared pulsed laser and collects the LIBS spectrum during the laser removal process of the top coating (TC), primer (PR), and aluminum substrate (AS). After subtracting the spectrum's continuous background and screening the key features, we construct a classification model of three types of spectra (TC, PR, and AS) based on a random forest algorithm, and the real-time monitoring criterion based on the classification model and multiple LIBS spectra was established and verified experimentally. The results show that the classification accuracy is 98.89%, the time-consuming classification is about 0.03ms per spectrum, and the monitoring results of the paint removal process are consistent with the macroscopic observation and microscopic profile analysis results of the samples. Overall, this research provides core technical support for the real-time monitoring and closed-loop control of LLCPR from aircraft skin.

Optimization of Laser Paint Removal Process for Carbon Fiber Composite Substrate Based on Response Surface Analysis

Optimization of Laser Paint Removal Process for Carbon Fiber Composite Substrate Based on Response Surface Analysis

A sustainable recycling process for end-of-life vehicle plastics: A case study on waste bumpers

End-of-life vehicle (ELV) recycling has considerable potential value and a wide range of applications. Plastics form an increasing percentage of the total weight of automobiles as their lightweight. Recycling plastics from automobiles is important for achieving the overall recycling goal from a sustainability standpoint. In this study, the whole recycling process of automotive plastic parts was explored, using waste bumpers as an example, in which paint removal and recycled polypropylene (RPP) modification were the important links. First, LS-Dyna was used to run simulations to determine the best paint removal process parameters for surface coating treatment, and experiments were then conducted to confirm the paint removal effect. Second, component, morphological, and Gel Permeation Chromatography (GPC) analyses were conducted. As per the results, the degradation was primarily caused by surface oxidation of the ELV bumper, and the molecular weight of RPP was lower than that of new PP. Finally, the thermal and mechanical properties of RPP, modified RPP, and the new bumper were compared. The addition of nano-montmorillonite(nano-MMT), virgin PP, and a compatibilizer could improve the thermal and mechanical properties of RPP while satisfying the application requirements of the new bumper. This process provides a valuable idea for the sustainable recycling of used ELV plastics.

Surface quality of laser paint removal of marine steel: a comparative study using a Gaussian beam and a flat-top beam.

The spot mode has a great influence on the effect of laser paint removal, but it has not been clarified. This paper studies the influence of a Gaussian beam and a flat-top beam on surface quality. The results show that for the laser paint removal with the Gaussian beam, the surface hardness, corrosion resistance, and adhesion of marine steel improved significantly. The surface hardness increased by a factor of 20.8% compared to the original substrate, and the paint adhesion increased by 32.7%. For the flat-top beam, the surface quality of the substrate is unchanged, but the cleaning efficiency was observed to be 20% higher than that of the Gaussian beam. This paper can provide technical support for the control of surface cleaning quality in the laser paint removal process.

LIBS Monitoring and Analysis of Laser-Based Layered Controlled Paint Removal from Aircraft Skin

Reliability and controllability of selective removal of multiple paint layers from the surface of aircraft skin depend on effective online monitoring technology. An analysis was performed on the multi-pulse laser-induced breakdown spectroscopy (LIBS) on the surface of the aluminum alloy substrate, primer, and topcoat. Based on that, an exploration was conducted on the changes of the characteristic peaks corresponding to the characteristic elements that are contained in the topcoat, primer, and substrate with different layers of a laser action, in combination with analysis of microscopic morphology, composition, and depth of laser multi-pulse pits. The results show that the appearance and increase of the characteristic peak intensity of the Ca I at the wavelength of 422.7 nm can be regarded as the basis for the complete removal of the topcoat; the decrease or disappearance of the characteristic peak intensity can be regarded as the basis for the complete removal of the primer. Al I spectrum at the wavelength of 394.5 nm and 396.2 nm can be adopted to characterize the degree of damage to the aluminum alloy substrate. The feasibility and accuracy of the LIBS technology for the laser selective paint removal process and effect monitoring of aircraft skin were verified. Demonstrating that under the premise of not damaging the substrate, laser-based layered controlled paint removal (LLCPR) from aircraft skin can be achieved by monitoring the spectrum and composition change law of specified wavelength position corresponding tothe characteristic elements that are contained in the specific paint layer.

Numerical simulation of paint stripping on CFRP by pulsed laser

Carbon-fiber-reinforced polymer (CFRP) composite is widely used in aerospace industry. The protective paint on the CFRP of aircraft needs to be removed after reaching a certain useful life. Laser cleaning has the advantages of high efficiency and environmental protection. However, the main obstacle to the application of laser cleaning on CFRP is the thermal damage caused by the laser radiation absorbed on the surface or inside of the substrate. In order to understand the interaction between laser and each layer of material, and the influence of laser parameters on the substrate temperature rise. Based on the ‘element death’ technique of the finite element (FE) method, a numerical model of material removal on a heterogeneous fiber–matrix mesh was established, which can accurately simulate the heat transfer process between carbon fiber and resin matrix. The effects of laser energy density, spot overlap rate and adjacent scanning line interval on material removal and the peak temperature of the substrate were investigated. The results show that the pulsed laser paint removal process will produce two high temperature zones on the resin layer and the heterogeneous material, and the superposition of adjacent pulse energy can significantly increase the temperature rise of the substrate.

Simulation of nanosecond laser cleaning the paint based on the thermal stress

Laser cleaning is a non-contact and straight forward method to remove the paint from the substrate, based on the mechanism of thermal stress. In order to understand the mechanism detailly, it is crucial to investigate the relationship between the laser fluence, interaction time and the temperature rise quantitatively. Herein, we exhibit thermal stress is the primarily mechanism in the paint removal process by nanosecond (ns) laser pulses. Based on this, a theoretical model of nanosecond laser peeling off the paint is developed successfully. It is worth mentioning that the formation of plasma, plasma shielding effect and temperature dependent absorptivity are critical factors, which is considered in this model. The model can predict the theoretical cleaning and damage thresholds based on the mechanism of thermal stress. According to the temperature distribution in this model, it could be found the optimized parameter is at the laser fluence of 1.56 J/cm2. Together, it is expected that this study could provide a theoretical reference regarding to nanosecond laser cleaning the paint layers and pave the way for reducing the substrate damage in various industrial applications.

Improved thermal stress model and its application in ultraviolet nanosecond laser cleaning of paint.

A developed 2D finite element model to describe temperature distribution, stress distribution, and ablation depth by ultraviolet nanosecond (ns) pulsed laser cleaning is presented. In this paper, we indicate that thermal stress is the primary mechanism in the paint removal process by laser cleaning and successfully simulate the ultraviolet nanosecond (ns) pulsed laser cleaning by the finite element method. Notably, the formation of plasma, plasma shielding effect on the incident laser fluence, temperature-dependent absorptivity, and absorption coefficient of the paint layer are crucial factors considered in this model. In addition, the tailored model can predict theoretical cleaning of thresholds based on the mechanism of thermal stress. According to the temperature, stress distribution, and cleaning depth in paint and substrate at various laser fluence in this model, the corresponding cleaning threshold is 7J/cm2 in theory. In a word, it is expected that this study could provide a theoretical reference regarding laser cleaning paint layers and pave the way for reducing substrate damage in various industrial applications.

Acoustic signal monitoring in laser paint cleaning

Laser paint removal has many advantages compared to traditional paint removal methods and has been widely used in the industry. A closed-loop control based on real-time monitoring of the laser paint removal process is essential to achieve a good clean effect without damaging the substrate. The acoustic signals generated in various stages have been studied experimentally. The results show that the property of the acoustic signal is closely correlated with the status of laser paint removal. The amplitude and the local standard deviation of the acoustic signal in the frequency range of 7–10 kHz gradually decreases to a steady value with the removal of the paint. The change of these two factors can reflect the status of laser paint removal more realistically than the signal amplitude in the time domain. Compared with the laser induced breakdown spectroscopy method, we found that monitoring based on acoustic signal works on a wider laser fluence range. We proved that this method can be used to evaluate whether the paint is cleaned or not when laser works in a scanning model. Our work can benefit the real-time monitoring and close-loop control of laser paint removal.

Laser paint removal monitoring based on time-resolved spectroscopy.

Laser paint removal is a new cleaning technology with high efficiency. Dynamic monitoring and closed-loop control of the laser paint removal process are key to reducing the risk of metal substrate damage and to achieving the best cleaning. In this paper, the time-resolved characteristics of the elemental peaks in the laser-induced breakdown spectrum of paints and substrate were studied by using the combination of a monochromator (or a bandpass filter) and a photomultiplier tube (PMT) detector. The results show that the intensity of the elemental spectrum peak of the paint has a sudden drop while the intensity of the elemental spectrum peak of the substrate has a sudden increase when the paint is removed. The time-resolved signals can be fitted by double exponential functions, which are combinations of exponential functions with a longer and a shorter lifetime, respectively. The relative ratios of the coefficients of the shorter and longer lifetimes (A s h o r t /A l o n g ) at the wavelength correspond to the elements in paint increasing suddenly while decreasing suddenly at the wavelength corresponding to the substrate. The intensity of the elemental spectrum peaks of paints and substrate and the ratio (A s h o r t /A l o n g ) can be used to monitor the laser paint removal process in real time to reduce the damage risk of the metal substrate and achieve the purpose of efficient cleaning with low cost.

Inhibition of flash rusting of HY80 by a mussel adhesive protein: Characterizing the interaction of MeFP-5 with a high strength low alloy steel

A proteinaceous biopolymer, mussel adhesive protein #5 (MeFP-5), isolated from the common blue mussel (Mytilus edulis L) has been investigated as a model for designing an aqueously soluble candidate corrosion inhibitor system that is non-toxic and environmentally friendly and is capable of inhibiting the flash rusting of exposed high strength low alloy (HSLA) steel surfaces during the paint removal process. In a previous study it was found that a significant amount of corrosion inhibition is possible (nearly 100% inhibition after 7 days) on HY80 steel in a 100% relative humidity environment at 40 °C. In an attempt to determine the possible mechanisms of corrosion inhibition, surface characterization of HY80 steel treated with various solutions containing the MeFP-5 biopolymer were performed. Fourier transform infrared (FT-IR) spectroscopy using attenuated total reflectance (ATR) of the protein adsorbed onto glass and metal surfaces indicated that complexation of the iron atoms on the oxyhydroxide covered metal surface involved the amino acid l-dopa and the primary amine of lysine. The involvement of these amino acids in the adsorption of the protein onto glass were much less evident. When the adsorbed protein was treated with a catechol oxidase enzyme, vibration bands consistent with metal complex formation involving l-dopa were not observed, indicating that the treatment with enzyme resulted in mess metal chelation at the surface oxide-protein film interface. Energy dispersive x-ray spectroscopy (EDS) findings indicate that iron content is highest where the MeFP-5 biopolymer is adsorbed onto the steel substrate at pH 5.5, 50% higher than the content of the iron on the steel surface alone. When the biopolymer is enzymatically cross-linked on the steel surface at pH 5.5, the iron content is decreased by 15% of that of the adsorbed biopolymer, suggesting that the iron at the steel surface is undergoing complexation and possible metal-mediated cross-linking, whereas the enzyme cross-linked protein on the steel surface complexes less of the iron. Three-dimensional modeling efforts of MeFP-5 suggest that specific domains of MeFP-5 where two amino acids, l-Dopa and lysine, are concentrated may be involved in adsorption to a metal oxyhydroxide film. These results indicate that it is possible to utilize the biochemistry of a naturally occurring biopolymer isolated from the marine mussel, Mytilus edulis (L), to develop a non-toxic and environmentally friendly corrosion inhibitor.

Research on mechanism and process of paint removal with pulsed fiber laser

Compared with the traditional cleaning technology, laser cleaning, as a new type of industrial technology, has the advantages of high cleaning rate, green pollution-free and low cost. So laser cleaning is widely used in the fields of paint removal. This paper analyzes that the mechanism of paint removal and heat transfer process in the paint layer and substrate, also determines the process parameters of affect the laser paint removal. The removal of paint from steel substrate with fiber laser of frequency adjustable 20 to 500kHz at 1064nm is reported, researching impact that laser energy density,scanning speed and line width on the paint removal effect. The results show that, the 100μm paint layer can be removed completely while keeping the substrate undamaged with the laser energy density of 10.19J/cm2 and speed of 4200mm/s and width of 0.02mm. In order to get better results, the cleaning efficiency can be improved by increasing the power, speed and spot size under the right energy density.

Possible Mechanism of Corrosion Inhibition of a High Strength Low Alloy Steel By a Mussel Adhesive Protein

A proteinaceous biopolymer, mussel adhesive protein #5 (MAP-5), isolated from the common blue mussel (Mytilus edulis L) has been investigated as a model for designing an aqueously soluble candidate corrosion inhibitor system that is non-toxic and environmentally friendly and that could inhibit the flash rusting of exposed high strength low alloy steel surfaces during the paint removal process. It was found that a significant amount of corrosion inhibition is possible (nearly 100% inhibition after 7 days) on HY80 steel in a 100% relative humidity environment at 40 °C. Indeed, these results were shown to surpass the performance of a commercially available flash rust inhibitor (90% inhibition after 7 days) currently in use on maritime vessels. These results indicated that it is possible to utilize the biochemistry of a naturally occurring biopolymer isolated from the marine mussel, Mytilus edulis (L), to develop a non-toxic and environmentally friendly corrosion inhibitor. This protein is unique in containing 27% L-dopa and 20% lysine, two unique amino acids containing catecholic and primary amine functional groups, respectively. To characterize how Mefp-5 interacts with the HY80 steel, a variety of analytical spectroscopy techniques were implemented. Solutions of Mefp-5, L-dopa or lysine dissolved in deionized water, 5% acetic acid, 0.05 M potassium phosphate buffer (pH 5.5), or the same buffer containing mushroom tyrosinase were adsorbed onto HY80 and glass substrates. Energy dispersive spectroscopy (EDS) measurements indicate that the iron content is highest where the MAP-5 biopolymer is adsorbed onto the steel substrate at pH 5.5, twice the content of the iron on the steel surface alone. When the biopolymer is enzymatically cross-linked on the steel surface at pH 5.5, the iron content is decreased by 1/3 of that of the adsorbed biopolymer. Raman infrared spectroscopy suggests that adsorbate, solution composition and pH play a role in the type of iron oxide formed and how the protein orients itself on the HY80 surface. At a pH of 5.5, the isoelectric point (pI) of the Fe2O3 oxide suggests the negatively charged oxide surface attracts lysine’s positively charged ε-amine group. Infrared spectroscopy indicates that L-dopa is also intimately involved in the adsorption of the protein and complexation of iron at the steel surface. 3-dimensional modeling of the MAP-5 protein indicates that the mole percent of L-dopa does not affect the conformation of the polymer in solution; however, results suggest that the amount of L-dopa contained within the polymer may have an effect on the corrosion inhibition efficiency. Overall, the data points toward a synergy existing between L-dopa and lysine, where lysine aids in coulombic attraction to the iron surface, allowing the protein to remain in close proximity and facilitating metal complexation by the L-dopa. The iron at the steel surface can undergo complexation as well as provide possible metal-mediated cross-linking of the protein; subsequent treatment of the adsorbed protein with enzyme results in additional cross-linking of the protein on the steel surface, thus complexing less of the iron. This scenario suggests that it is possible to engineer a corrosion inhibitor that meets the need for low volatile organic content, is aqueously soluble and environmentally benign.

The Effect of Atmospheric Plasma Paint Stripping on the Fatigue Crack Growth Properties of Aluminium Substrates

Paint removal is a common maintenance requirement for aircraft as well as naval and land vehicles, since external paint gets damaged and loses much of its corrosion protection effectiveness with time. Paint removal is also conducted when metallic aircraft structures are inspected periodically for fatigue cracks and corrosion. The conventional methods of removing paint employed throughout the Canadian Forces mainly include chemical stripping and abrasive media blasting. Chemical stripping involves the use of hazardous chemicals, which are high in Volatile Organic Compounds (VOC) and Hazardous Air Pollutants (HAP). Abrasive media blasting typically results in a substantial quantity of solid waste consisting of paint and blast residues. Such waste is subject to control under increasingly stringent environmental and safety regulations and its disposal is costly. The new Atmospheric Plasma (AP) paint removal process purports to be a high chemical energy, low thermal energy (cold plasma process), that should not damage temperature sensitive substructures, such as heat treated aerospace aluminium alloys. Fatigue strength is one of the key properties in aircraft structures. In order for AP paint stripping to be accepted as an aerospace industry standard paint removal process, it must be thoroughly tested to demonstrate that it does not adversely affect the fatigue properties of the substrate. This paper investigates effect of the paint removal process on fatigue crack growth of 7075-T6 and 2024-T3 aluminium panels.

Alternate Environmentally Friendly De-Painting Process for Aircraft Structures-Atmospheric Plasma

During the lifetime of aircraft structures, paint removal and re-application cycles are conducted to restore appearance and to enable inspection for fatigue cracks and corrosion damages. Current paint removals processes, including chemical and abrasive media blasting, yield large amounts of volatile organic compounds and hazardous air pollutants, and generate large quantities of waste which require proper disposal/treatment. They also have the potential to mask surface cracks and decrease the effectiveness of Liquid Penetrant Inspections (LPI). This study compares current paint stripping methods to a novel Atmospheric Plasma (AP) system, which claims to be a more environmentally friendly method. Aluminium and steel coupons were prepared with military aircraft quality topcoat and primer paint schemes and subjected to the three aforemen-tioned paint stripping processes. The results were then characterized in terms of paint removal effectiveness, potential damages to the metallic substrates, and effect on the LPI process. Hardness and conductivity measurements as well as metallographic sectioning and microscopy, were used to characterize the stripped samples. The results indicated that AP had no negative ramifications on detecting fatigue cracks in the substrates, and did not alter the temper, mechanical properties of the aerospace alloys studied. The AP process has the potential to replace current hazardous and less environmentally friendly paint removal methods; though a full systematic qualification and evaluation process is still required for it to be considered as an accepted industrial paint removal process.

Inhibition of Flash Rusting of HY80 By a Mussel Adhesive Protein: Characterizing the Interaction of MAP-5 with a High Strength Low Alloy Steel

A proteinaceous biopolymer, mussel adhesive protein #5, isolated from the common blue mussel (Mytilus edulis L) has been investigated as a model for designing an aqueously soluble candidate corrosion inhibitor system that is non-toxic and environmentally friendly and that could inhibit the flash rusting of exposed high strength low alloy steel surfaces during the paint removal process. It was found that a significant amount of corrosion inhibition is possible (100% inhibition after 7 days) on HY80 steel in a 100% relative humidity environment at 95°F. Indeed, these results were shown to surpass the performance of a commercially available flash rust inhibitor (90% inhibition after 7 days) currently in use on maritime vessels. These results indicated that it is possible to utilize the biochemistry of a naturally occurring biopolymer isolated from the marine mussel, Mytilus edulis (L), to develop a non-toxic and environmentally friendly corrosion inhibitor. This protein is unique in containing 27% L-Dopa and 20% lysine, two unique amino acids containing catecholic and primary amine functional groups, respectively. Currently, characterization of the interaction of the MAP-5 biopolymer on the steel substrate is underway to better understand its mechanism of corrosion inhibition. Energy dispersive spectroscopy (EDS) findings indicate that iron content is highest where the MAP-5 biopolymer is adsorbed onto the steel substrate at pH 5.5, twice the content of the iron on the steel surface alone. When the biopolymer is enzymatically cross-linked on the steel surface at pH 5.5, the iron content is decreased by 1/3 of that of the adsorbed biopolymer. These results suggest that the iron at the steel surface is undergoing complexation and possible metal-mediated cross-linking, whereas the enzyme cross-linked protein on the steel surface complexes less of the iron. Further EDS analysis indicates that when the biopolymer is first dissolved in acetic acid and then phosphate buffer added and placed on the HY80 surface, the same amount of iron is present for all conditions indicating that the presence of acetate or a more acidic pH inhibits any complexation of the iron by the biopolymer as well as any enzymatic cross-linking. Fourier transform infrared (FTIR) spectroscopy using attenuated total reflectance (ATR) and nanoscale IR spectroscopy of the MAP-5 adsorbed onto the steel substrate indicates that the peaks associated with the L-Dopa catecholic hydroxyl groups (-OH) present are very much diminished on the HY80 substrate vs on glass, whereas the aromatic benzene ring peak assignment of the catechol is present on both substrates, confirming the complexation of the surface iron atoms. However, the primary amine (NH3+) functional group present in the amino acid lysine is present in numerous peak assignments on both substrates, with deformation and scissoring, indicating their orientation at the metal surface. It has been suggested that the primary amine may allow for displacement of hydroxyl groups on a metal hydroxide surface, thus allowing the formation of a bi-dentate catechol complex by the L-Dopa amino acids present within the proteinaceous polymer.