Coating Adhesion Test Research Articles

Study of resin coating adhesion on GFRP laminate surfaces after UV degradation

This paper describes research on the effect of UV radiation on the surface of a GFRP (Glass Fiber Reinforced Polymer) laminate in the context of increasing the adhesion between the laminate and polymer resin coatings. GFRP composite samples were prepared using the hand lay-up method. The samples were then exposed to various types of ultraviolet radiation (UVA, UVB, UVC) for 1000 h, with surface roughness measurements every 100 h. The flexural strength of laminates after photoaging was tested, which showed an increase in the strength of aged laminates compared to the reference sample by approximately 5–10 %. Coatings of various thicknesses were applied to the surface of the aged laminates and their adhesion to the substrate material was tested using the mandrel bending method alongside the cross-cut technique. The greatest change in surface roughness was observed on the sample exposed to UVC radiation, where the roughness increased approximately twice in relation to the reference sample. Coating adhesion tests have additionally shown that degradation under the influence of UVC has a positive effect on the adhesion of coatings to the laminate.

Fabrication and properties of recyclable tung oil–based polymer coatings based on dual cross-linked dynamic covalent polymer networks

The exploration of reprocessability and high-adhesion biomass polymer coatings is in line with the concept of green materials and is conducive to energy conservation and environmental protection. Here, a series of novel recyclable tung oil–based polymer coatings based on dual cross-linked dynamic covalent networks were reported. Tung oil polymerized maleic anhydride (TOA) was firstly prepared and further reacted with furfuryl alcohol. Then tung oil-polymerized maleic furanol ester (TOAFA) containing reactive conjugated double bond and carboxyl groups was prepared. FTIR and 1H NMR demonstrated the reactive monomer TOAFA was successfully synthesized. Then TOAFA was cross-linked with bismaleimide and different epoxy resins to fabricate target polymer networks based on dynamic Diels-Alder(D-A) bonds and dynamic transesterification. The shape memory, reprocessing, and mechanical and thermal stability of the copolymerized systems with different crosslinking states were investigated. The coating performances were characterized with solvent resistance, adhesion strength, hardness and glossiness tests. It was found that the dynamic D-A covalent bonds were perfectly combined with transesterification in the polymerization systems. The copolymerized systems possessed excellent thermal stability and mechanical properties. The rigid and flexible properties of the polymer networks can be controlled by adjusting the component weight ratios and the type of epoxy resin in the polymerization system. The rigid polymerization system had the highest tensile strength of 28 MPa, and its elongation at break was up to 57 % of the flexible polymerization system. Coating adhesion test showed the adhesion property reached level 1. The polymer coatings displayed excellent solvent corrosion resistance, and relative high gloss. The polymer networks also showed certain reprocessing performance and excellent shape memory effect.

Flame-Retardant and Smoke-Suppression Properties of Bamboo Scrimber Coated with Hexagonal Boron Nitride

In order to improve the flame-retardant properties of bamboo scrimber, chitosan (CS) and polyvinyl alcohol (PVA) were used as the film-forming substances, and hexagonal boron nitride (h-BN) was used as the flame-retardant substance to prepare h-BN flame-retardant coatings, which were coated on the surface of the bamboo scrimber. The effects of the h-BN flame-retardant coatings with different quality concentrations on the flame-retardant properties of the bamboo scrimber, as well as on the morphology of the residual carbon, were investigated using the analytical methods of FTIR, environmental scanning electron microscopy, thermogravimetric analysis, combustion test, and coating adhesion test. The results showed that the h-BN flame-retardant coating could improve the thermal stability of the bamboo scrimber and that the higher the mass concentration, the better the thermal stability of the h-BN. Compared to the control, the time to ignition (TTI) of the 5% h-BN flame-retardant-treated specimens increased by 56%; the peak heat release rate (Pk-HRR), total heat release (THR), and total smoke production (TSP) decreased by 9.92%, 7.54%, and 32.35%, respectively; however, due to the presence of PVA, the peak smoke production rate (Pk-SPR) increased by 17.78%. The 5% h-BN coating had very good adhesion, with an adhesion grade of zero. In conclusion, the h-BN coating could be well-adhered to the surface of the bamboo scrimber, and the 5% h-BN flame-retardant coating had a better flame retardancy compared to other treatments, meaning that it could provide a new strategy for improving the flame-retardant properties of bamboo scrimber for construction use.

Effectiveness of Bonding Steel Elements with Polyester-Coated Paint

The aim of the paper is to assess the impact of the effectiveness of bonding steel elements with paint coating. The adhesive joints were made using two types of the adhesives: two-component epoxy resin adhesive based on Bisphenol A and polyurethane. Three types of adhesive joints were made: (i) reference samples, (ii) samples with a paint polyester coating, and (iii) samples with a zinc primer and paint polyester coating. These coatings were applied using the electrokinetic method. A shear strength test of the adhesive joints (EN DIN 1465 standard), a coating adhesion test (ASTM D3359-B standard), and surface wettability tests (based on contact angle) were used. Through analyzing the test results, it can be seen that the strength of the adhesive joints of the reference samples made with epoxy adhesive is 46% lower than that of the specimens with primer and paint coating applied. However, in the case of the adhesive joints made with the polyurethane adhesive, the aforementioned difference in the strength value of the adhesive joints of the reference samples and paint-coated samples with an applied primer is 76%. Adherends with a paint coating and a previously applied primer obtained the lowest value of the contact angle (38.72°) and are characterized by good wettability.

Analysis of the Adhesion of the Surface Layer Formed due to Cataphoresis Coating

The paper focuses on the cross-cut test, which serves as a basis for determining the adhesion test on the surface of aluminium parts. The coating adhesion test was performed according to the ISO 2409 standard where. Before carrying out the actual measurement, the tools necessary for making those individual measurements were prepared. A knife, an adhesive tape and a grid were used. The result was evaluated on the basis of the ISO 2409 standard. Spacing of a grid was 2mm apart. Grid exam cut test was carried out on 32 samples. The classification of the samples ranged from 0 to 1. At 1, we found that the surface of the material was slightly damaged. At the scale of 0, a smooth cut was made on the material surface, and no damage occurred. Through research, we found that with a constant chemical degreasing factor, the adhesion test varies according to the EN ISO 2409 standard at values 0 and 1. It follows that if we wanted to achieve worse cutting conditions in the grid, we would have to change the temperature of the solution, the time depositions.

Mode mixity and fracture in pull-off adhesion tests

Following pull-off coating adhesion tests such as ASTM D4541, visual examination of the fracture surfaces often reveals intriguing fracture patterns where similar (and seemingly predictable) features are observed across like coating systems. Nonetheless, adhesion test stubs are typically discarded after a brief visual inspection or no inspection at all—suggesting a missed opportunity to gain further insight into fracture processes. This paper examines the pull-off adhesion test from a fracture mechanics perspective. We present two microscopy-based methods for extracting analytically useful fracture data from pull-off adhesion tests. First, we develop an energy-based method for obtaining mode mixity from observed crack kink angles, providing the powerful capability to disambiguate mode I and mode II fracture. We demonstrate agreement between experimental results and theoretical predictions in a set of 1,305 crack path measurements for 111 pull-off adhesion test stubs, representing both single- and multi-layered coating systems. Second, we deploy a machine-learning based image segmentation technique (Trainable WEKA) to rapidly quantify the fractional area coverage of materials removed with the pull stub, enabling further insight into the surfaces most vulnerable to delamination in a layered coating stack. Beyond the immediate utility of these techniques for data enhancement in pull-off adhesion tests, these techniques also have long-term potential as tools for failure analysis in coated systems.

Influence of Surface Treatment on Steel Adhesive Joints Strength-Varnish Coats.

The purpose of the paper is to determine the impact of surface treatment on the strength of adhesive joints, made from various steel sheets. Two variants of the surface treatment steel adherends were used: without the varnish coat and with the varnish coat, using three polymer-based varnishes (a simple, a hybrid, and a gel). Two types of the adhesives were used to prepare the adhesive joints: a single-component cyanoacrylate adhesive and a two-component epoxy adhesive. A strength test of the adhesive joints (EN DIN 1465 standard), a coating adhesion test (ASTM D3359-B standard), and surface topography, as well as surface roughness, parameters (PN-EN ISO 11562, PN-EN ISO 4287, and PN-EN ISO 25178 standards) were used. Based on the strength tests, it was observed that the adhesive joints, with the hybrid varnish onto the adherend’s surface, achieved markedly lower shear strength. The best results, in terms of the adhesive joint strength, made using the cyanoacrylate adhesive were achieved for the joints where the adherends were coated with a simple varnish, while in the joints made using the epoxy adhesive, the highest shear strength was achieved by the joints of sheets whose surfaces were coated with the gel varnish.

Design of the double-layer biocompatible coating on AZ31 magnesium alloy for highly effective corrosion resistance

A double-layer phytic acid@cerium/polycaprolactone@cerium substituted hydroxyapatite (PA@Ce/PCL@Ce-HA) composite coating was prepared on the AZ31 Mg alloys combining the cyclic assembly and electrospinning techniques. SEM images showed that the out layer of PA@Ce/PCL@Ce-HA coating displayed a typical disorderly distributed nanofiber structure, and the average diameter of the PCL@Ce-HA fibers was 680 ± 45 nm. ATR-FTIR and XPS analysis demonstrated the existence of typical characteristic peaks of PO43− groups in the composite coating, indicating PA molecular and Ce-HA nanoparticles were successfully anchored to the alkaline pretreated Mg substrate. The results showed that this composite coating was composed of an inner PA@Ce complex and an outer PCL@Ce-HA nanofiber coating. The cross-section images verified that the thickness of the composite coating was 74.94 ± 2.14 μm. The coating adhesion tests indicated that the bonding strength between outer fibrous PCL@Ce-HA and substrates were improved, owning to the mechanical interaction and entanglement between fibrous coatings and the rough PA@Ce coating. Electrochemical tests showed the corrosion current density of PA@Ce/PCL@Ce-HA coated sample significantly dropped by two orders of magnitude compared to uncoated sample, indicating this coating significantly reduced the corrosion rate of the substrates. In addition, the lowest amount of hydrogen evolution and the minimal variation of pH value in the in-vitro immersion tests further confirmed that the PA@Ce/PCL@Ce-HA coating had a long-term stable corrosion protection for the substrates. Furthermore, the cell experiments showed that the double-layer coating provided an interface similar to the extracellular matrix (ECM), which was conducive to the attachment and proliferation of human osteoblast MG-63 cells. The hemolysis rate (HR) of PA@Ce/PCL@Ce-HA coated sample was 1.69%, which met the requirements of biomedical material applications. Thus, the outcomes of this work provided a new sight for corrosion protection of the Mg alloys and this coating has great potential in orthopedic applications.

Revised notched coating adhesion test to account for plasticity and 3D behaviour

Specialized polyamide-imide coating on a CuSn10Pb10 substrate, a material combination utilized often in modern bearing applications, is fabricated using the solvent casting method. The coating adhesion is studied using the well-known notched coating adhesion (NCA) test. Conventionally, the critical strain required to cause the debond propagation is determined by visual observation and indirectly linked to measured strain data to calculate fracture toughness. Here, digital image correlation (DIC) is used to systemically study the coating deformations during testing that enables quantitative determination of the instantaneous debond length. With the introduced method, the critical strain to induce the debond of the coating and the propagation of the debond can be determined for non-elastically behaving specimens reliably. The coating’s debond onset is studied with virtual crack closure technique (VCCT) here. The method can take 3D effects into account in detail and provides a sophisticated method to determine the critical energy release rate. Additionally, cohesive zone modelling (CZM) is used to simulate debond progression. Nonlinear stress–strain responses are observed taking place both with the coating and the substrate materials. The results emphasize that the coating plasticity has a remarkable role in the test behaviour which needs to be taken into account in the revised analysis.

Preparation and characterization of the catechol functionalized chitosan-Ag NPs deposited onto titanium surface

The bacterial infection is one of the main reasons for the failure of implant surgery. In this paper, catechol functionalized chitosan (CSCT) was used as a reducing agent and stabilizer to synthesize CSCT-Ag NPs. The composite coating of titanium surface was then electrodeposited by a CSCT layer initially, followed by spin-coating of a CSCT/gelatin (G)/CSCT-Ag NPs layer. The results of XRD, UV–Vis, and TEM showed that the silver nanoparticles were successfully synthesized with uniform distribution, and the particle size was 4–22 nm. The cytotoxicity test results of CSCT-Ag NPs on A549 and EA.Hy926 cells showed when the concentration of CSCT-Ag NPs was less than 25 μg/mL, the survival rate of the two kinds of cells was greater than 80%. First electrodeposition and then spin-coating is feasible through the coating adhesion test and the adhesion level up to 5B. Compared with the pure Ti substrate, the corrosion resistance and hydrophilicity of the composite coating surface are significantly improved. The antibacterial rate of the composite coating against E. coli and S. aureus can reach 99% and 96%. In conclusion, CSCT-Ag NPs and the method of preparing coatings by electrodeposition and then spin-coating have good clinical application potential.

Influence of surface modification of Ti6Al7Nb alloy on adhesion of poly (lactide-co-glycolide) coating (PLGA)

The paper presents the results of studies on the influence of surface topography and wettability of a Ti6Al7Nb alloy substrate on the adhesion of a PLGA coating. The alloy surface was modified using a mechanical pre-treatment including: grinding, vibration treatment, mechanical polishing, sandblasting and anodic oxidation. The polymer coating was applied to the metal substrate by a dip-coating method. The scope of the research included microscopic observations of the substrate and polymer coating using SEM and acoustic microscopy. In addition, studies on the wettability and topography of the polymer coating and the metal substrate, the thickness of the polymer coating as well as qualitative and quantitative testing of the adhesion of the polymer coating to the substrate were carried out. Coating adhesion tests were conducted for samples in the initial state and after 6 weeks exposure to Ringer's solution.Analysis of the results indicates the influence of the method used to modify the metal substrate on its topography and wettability. These parameters affect the thickness of the obtained polymer coating. Regardless the parameters of the metal substrate, a qualitative analysis of the adhesion of the coating applied to the substrate of the Ti6Al7Nb alloy did not show any delamination for both samples exposed and non-exposed to Ringer's solution. On the other hand, quantitative scratch-test studies showed different adhesion of the polymer coating to the substrate depending on the surface topography obtained by various modification methods.The cytotoxicity test conducted by the indirect method using extracts confirmed that the surface modification does not affect cell growth.The complex methods of surface pre-treatment of the alloy together with the kind of polymer selected for the study allowed to develop well adhered PLGA layers on Ti6Al7Nb intended for short term implants. The lack of delamination of the layer during 6 weeks was proved, what allows for maintaining the protection function of the layer during this period and contribute to improving biocompatibility.

Coating adhesion of a chromate-containing epoxy primer on Al2024-T3 surface processed by laser-interference

In this study, the coating adhesion test results are presented for a primer that was coated on laser-interference structured surfaces of as-received Al2024-T3 specimens, i.e., without employing any polishing, cleaning, or any other surface alteration techniques. All of the laser-interference processing was performed by splitting the primary beam of a Q-switched Nd:YAG pulsed nanosecond laser into two beams and focused them to the same spot. The specimens were spray painted with a chromate-containing epoxy primer, CA7233, compliant to MIL-PRF-23377 Type I Class C2 specification. The adhesion of primer on Al surface with different treatments was assessed using the ASTM D3359 X-cut and cross-hatch tests. It was found that the laser processed specimens meet the performance requirements in the coating adhesion specifications by having a higher or identical ranking for coating adhesion specimens than those prepared with current state-of-the-art chemical conversion or sulfuric acid anodizing. The rastering with either 4 mm/s or 6 mm/s with a laser fluence of 1.78 J/cm2 is recommended to attain acceptable coating adhesion, even higher than that with the anodizing surface treatment.These results indicate that laser-interference shows significant potential as a non-chemical surface preparation technique for these coatings.

Electroless nickel underlayer deposited between copper filler and silicon substrate: effect of bath pH

ABSTRACT This research proposed intermediate materials between Cu filler and Si wafer to reduce the coefficient of thermal expansion (CTE) mismatch in the through silicon via (TSV) structure. The proposed material is Ni underlayer because it has CTE value between Cu and SiO2 which is 13 ppm/°C (Cu = 17 ppm/°C, SiO2 = 0.6 ppm/°C). The deposition process of nickel underlayer was conducted using electroless deposition process at various pH value (4.5, 5.5 and 6.5) of plating bath and deposition time (20, 40 and 60 minutes). The deposition behaviour was studied through surface and cross-sectional analysis under scanning electron microscopy (SEM). The Ni thickness was measured using cross-sectional analysis under SEM. The chemical composition of Ni deposits was measured using energy dispersive spectroscopy equipped on SEM. The performance test analysis was conducted using Standard ASTM D3359 (Cross Hatch Tape-Test) for coating adhesion test and 4-Point Probe Test for resistivity measurement. It was found that the optimum pH of the Ni bath is 6.5 due to high stability of plating bath to form uniform Ni deposited on silicon wafer. These optimum coating parameters showed homogeneous and uniform distribution of Nickel deposited on the surface of silicon with excellent adhesion properties for all pH value.

The Effect of Temperature on Nickel Deposited as an Underlayer Between Copper Filler and Silicon Wafer

Through silicon via (TSV) has garnered a lot of interest in the semiconductor industry due to its ability to provide the shortest interconnect path. The coefficient of thermal expansion (CTE) mismatch between the copper (Cu) interconnection filler and the silicon (Si) wafer result in reliability issues of the TSV system. This research proposed the introduction of an underlayer between the Cu filler and Si wafer in order to reduce the CTE mismatch in the TSV. The chosen underlayer is nickel (Ni) as it has a CTE value placed in between Cu and Si at 13 ppm/°C (Cu = 17 ppm/°C, Si = 2.8 ppm/°C). The Ni layer was deposited using the electroless deposition process at different temperature of plating bath (75 °C, 85 °C, and 95 °C) and deposition time (20, 40, and 60 minutes). The analysis of the microstructure of the Ni layer deposited on the Si wafer was characterized. The adhesion test was conducted using the ATM D3359 (Measuring Adhesion by Tape Test) Standard for coating adhesion test and the 4-Point Probe Test for the resistivity measurement. It was found that the optimum Ni plating temperature was at 85 °C based on its adhesion and high stability of plating bath. The resistivity test showed that the increased of Nickel underlayer thickness deposited between copper and Si wafer has slightly increased the resistivity.

The Role of Laser Texturing in Improving the Adhesion of Plasma Sprayed Tungsten Coatings

Plasma sprayed W-based coatings have the potential application as joining interlayers for the plasma-facing components of future fusion reactors. Particularly in the form of tungsten-steel functionally graded materials (FGMs), they would reduce the stress concentration between the W-based plasma-facing armor and steel-based construction. For mechanical integrity, good adhesion is essential. For this, conventional grit blasting treatment of the substrate may not be sufficient. Therefore, alternative treatments capable of reaching significantly higher roughness without damaging the substrate are sought. In this study, the effects of laser texturing on the adhesion of plasma sprayed W and W-steel FGMs on W and steel substrates are investigated. A variety of surface profiles were achieved by controlled laser ablation in several types of patterns. Their geometric features were systematically varied and measured, and the extent of their filling by the coating material was evaluated. On the most promising patterns, coating adhesion tests were performed in shear loading mode and the best performing patterns were identified. Significant improvement over grit-blasted surface was obtained on patterned surfaces with a high effective contact area, promoting mechanical interlocking. On steel substrates, generally higher adhesion was observed, surpassing already the coating cohesive strength; this is attributed to a combination of mechanical interlocking and metallurgical bonding.

Investigation Into the Performance of a Dual-Layer Thin-Film Organic Coating During Accelerated Low-Temperature Offshore Testing

The application of thin-film coatings is a method to protect armatures, accessories, and control elements on offshore facilities against corrosion and mechanical damages. The performance of a dual-layer thin-film (30 μm) coating system under simulated Arctic offshore exposure was investigated. The coating system consisted of polyamide-based primer and molybdenum-disulfide (MoS2)/polytetrafluoroethylene (PTFE)—modified topcoat. The investigations involved the following tests: accelerated corrosion protection/aging tests, coating adhesion tests, scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX) inspections, static contact angle measurements, specific surface energy measurements, hoarfrost accretion, and abrasion resistance tests. The test conditions were adapted to Arctic offshore conditions. Effects of accelerated offshore aging on surface morphology, surface chemistry, and hoarfrost accretion were also investigated.

Enhanced corrosion resistance and biocompatibility of AZ31 Mg alloy using PCL/ZnO NPs via electrospinning

In the efforts to improve corrosion resistance and biocompatibility of magnesium alloys, polycarprolactone (PCL) and zinc oxide nanoparticles (ZnO NPs) composite coatings were applied onto AZ31 Mg alloys via electrospinning technique in this study. The PCL/ZnO composite coatings on Mg alloys were characterized by using FE-SEM, EDX, XPS, and FT-IR. Moreover, coating adhesion test, electrochemical corrosion test, and biocompatibility test in vitro were performed to measure coating performance. Our results revealed that the increase in the content of ZnO NPs in the composite coatings not only improved the coating adhesion of composite coatings on Mg alloys, but also increased the corrosion resistance. Furthermore, the biocompatibility of MC3T3-E1 osteoblasts of the PCL/ZnO composite coated samples was superior to the biocompatibility of the bare samples. Such data suggest that applying PCL/ZnO composite coating to the magnesium alloys has suitable potential in biomedical applications.

Pine Wood Treated with a Citric Acid and Glycerol Mixture: Biomaterial Performance Improved by a Bio-byproduct

Wood material is a good reservoir for biogenic carbon storage. The use of wood material for outdoor products such as siding in the building construction sector presents limits. These limits are bound to the nature of wood material (hygroscopic property and anatomical structure). They are responsible for the dimensional variation associated with moisture content variations. Fungal attacks and coating layers adhesion on wood surface, are other problems. This research investigated the feasibility of impregnation with environmentally friendly chemicals, i.e., a citric acid-glycerol mixture (CA-G). The anti-swelling efficiency (ASE), hardness, biodegradation, and coating adhesion tests were performed on softwood specimens. ASE results were up to 53%. The equilibrium moisture content of the treated specimens was less than half of the untreated ones. FTIR spectroscopy showed bands at 1720 to 1750 cm-1, indicating the presence of ester bonds, and scanning electron microscopy images confirmed the polymerization and condensation of treatment solution inside the wood structure. Hardness and decay resistance were increased; however, treatment reduces coating adhesion. In conclusion, CA-G represents a promising eco-responsible solution for improving the technical performance of outdoor wood products.

The Impact of Sinter and Thermoprint on Film Formation of nanoTiO2 Slurry

nanoTiO2 is one of the most important inorganic pigments in many different fields. The effect of sinter and thermoprint on film-forming properties of nanoTiO2 in screen printing were studied in this paper. Compared with sintering, Thermoprint uses high temperature and pressure to make nanoparticles more tight. By scanning electron microscopy (SEM), X-ray diffraction (XRD) and Coating Adhesion Test, the better film-formation properties of thermoprint are demonstrated.

Development of an improved tube galvanizing process by prior metallic coating

Tube galvanizing is a very old and important process industrially. One of the significant process steps in tube galvanizing is the use of flux materials on cleaned tubes for temporary protection before dipping into the liquid zinc bath. However, the fluxing operation is somewhat hazardous and also causes zinc loss by dross and ash generation. An attempt has been made here for the first time to replace fluxing operation by applying a thin metal flash coating on clean tubes prior to galvanizing. The galvanized tubes are then characterized by SEM and EDS to find out the coating thickness and evolved phases. The galvanized tubes are subjected to corrosion tests and coating adhesion tests. The results are very encouraging confirming the presence of desired phases along with excellent corrosion resistance of these tubes.