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The purpose of this paper is to present a new test method (tape peel method) to evaluate conformal coating adhesion to electronic assemblies.

The key issue for this method is the low cohesive force of conformal coatings, and hence selection of a supporting material to peel the coating from the substrate is critical. A suitable cloth material (35 per cent cotton +75 per cent polyester with 20 per cent open area) has been selected as a peel tape, and achieved the best bonding with coatings, and the smallest affect on the coating curing process. Using the tape, the peel force of the coating from the electronic assembly, can be measured quantitatively, and hence the adhesion performance of the conformal coating assessed.

The method was validated using different coating types, substrate materials (bare laminate with and without resist, copper clad laminate, and contaminated laminate material), assemblies and components. The results demonstrated that the tape peel test is a sensitive method for measuring coating adhesion on different materials found on PCB assemblies. Coating adhesion was found not to be effected by a wide range flux residues, but components and some resists presented a far greater coating challenge, with some coatings achieving very low adhesion values.

This new method for evaluating conformal coating adhesion to electronic assemblies will be of benefit to coating developers and users, and help to minimise adhesion failures in service. The test has been demonstrated to be sensitive to a number of process and material variables.

The disbonding of DLC coating is a main failure mode in the high-speed cavitation condition, which shortens the service life of the bearing. This study aims to investigate influence of adhesion strength on cavitation erosion resistance of DLC coating.

Three DLC coatings with different adhesion strengths were grown on the 304 steel surfaces by using a cathodic arc plasma deposition method. Cavitation tests were performed by using a vibratory test rig to investigate the influence of adhesion strength on cavitation erosion resistance of a DLC coating. The cavitation mechanism of the substrate-coating systems was further discussed by means of surface analyses.

The results indicated that, the residual stress decreased and then increased with the increasing DLC coating thickness from 1 µm to 2.9 µm, and the lower residual stress can improve the adhesion strength of the DLC coating to the substrate. It was also concluded that, the plastic deformation as well as the fracture occurred on the DLC coating surface at the same time, owing to higher residual stress and poorer adhesion strength. However, lower residual stress and better adhesion strength could help resist the occurrence of the coating fracture.

Cavitation tests were performed by using a vibratory test rig to investigate the influence of adhesion strength on cavitation erosion resistance of the DLC coating. The plastic deformation and the fracture occurred on the DLC coating surface at the same time, owing to higher residual stress and poorer adhesion of coating. Lower residual stress and better adhesion of coating could resist the occurrence of the DLC coating fracture.

The paper's aim is to investigate improvement of strength and adhesion of silicone‐acrylic hybrid systems.

The presence of Si‐C bonds in phenyl silicone should be able to improve strength, adhesion and thermal properties of phenyl silicone‐acrylic polyol coating. Different weight ratios of phenyl silicone and acrylic polyol resins were blended in order to obtain the composition for optimum strength, adhesion and thermal properties. Strength was evaluated using an impact resistance tester. Coating adhesion was studied by measuring the contact angle and performing cross hatch cutting. The thermal properties were studied using differential scanning calorimetry.

Blending phenyl silicone intermediate resin with acrylic polyol resin showed significant improvement in strength and adhesion properties compared to pure acrylic polyol resin. This paper shows that the composition of such coatings influences the glass transition temperature (T_g), which in turn affects the strength and adhesion properties of the coatings. The coating consisting of 30 per cent silicone resin and 70 per cent acrylic resin showed good adhesion and impact resistance properties on cold roll mild steel panels.

Findings may be useful in the development of heat resistant and anti‐corrosion paints.

The blending method provides a simple and practical solution to improve the strength and adhesion properties of acrylic polyol resins.

Durability and functionality of the coating critically depend on the strength and adhesion properties of the materials. This may be a useful source of information for the development of organic‐inorganic coatings.

The purpose of this study is to design and develop a new functional coating system for aerospace AL7075-T6 alloy that would evaluate the mechanical properties of the coating.

This paper outlines the scratch adhesion characterisation of Cr/CrAlN coating using a combination of radio frequency (RF) and direct current (DC) physical vapour deposition (PVD) magnetron sputtering. The surface morphology, microstructure and chemical composition of the Cr/CrAlN film were evaluated by optical microscopy (OM), field emission scanning electron microscopy (FESEM) integrated with energy-dispersive X-Ray spectroscopy (EDX) and atomic force microscopy (AFM). The film-to-substrate adhesion was measured by a scratch test machine manufactured with a detection system, motorized stages, penetration depth sensors, optical microscope and tangential frictional load sensors.

The AFM and ultra-micro hardness results showed an increase in surface roughness to about 20 per cent and hardness to about 74 per cent. Moreover, the film-to-substrate adhesion strength of 1,814 mN was obtained with PVD deposition process.

The main limitation of this work is caused by PVD deposition process. Besides, surface defects such as pinholes contribute to a decrease in adhesion strength.

The higher hardness of CrAlN coating is used to improve the properties of softer aluminium substrates. This hardness prevents ploughing-induced wear and provides greater adhesion strength by preventing coating delamination.

Until now, CrAlN is coated only on ferrous alloys. It has not yet been tried on aluminium alloys. Moreover, coating functionality depends on higher adhesion and failure mechanisms involved in the film-to-substrate system, which is significant in aerospace applications.

The purpose of this work was to study the effect of different wood surface preparations on the wetting and adhesion of coating.

In this research, six different chemical preparations to evaluate the photostability and properties of wood coating. Also, the effect of the same wood treatments on the properties of the coating, i.e. wetting, adhesion and the permeability of two types of coatings, was investigated.

As a result, benzoyl chloride and chromic acid were found to be the most effective photostabilizing preparations. Solvent-based polyurethane was more compatible with the prepared wood surfaces compared with water-based alkyd coatings.

Chemical modifications of wood surfaces affected the wetting of various coatings.

Various surface properties could be changed using preparation that affects important coating properties.

Unfortunately, the properties of transparent wood coatings used outdoors disappear through the early years of use, essentially due to the wood substrate’s photodegradation.

Wood is a widespread substrate because of its comfortable handling, availability, proper cost of preparation and its good mechanical strength because of its density. Architects and designers tend to use wood in the construction of green buildings. However, this material is disposed to weathering while using outdoors and it should be solved.

This paper aims to increase protection behavior of epoxy coating on aluminum alloys with plasma electrolitic oxidation (PEO) process as pretreatment and to investigate the corrosion properties of duplex coating system on aluminum alloy.

The study used micro structure study, electrochemical impedance spectroscopy (EIS) investigation, water uptake investigation and pull-off test.

This study was done to investigate the effect of urea as an additive, which alters the current density and time of process parameters in the protective performance of epoxy coating on the aluminum substrate. The protective behavior of double-layer coatings was examined using EIS in 3.5 per cent NaCl solution. In addition, the adhesion strength of double-layer coatings was evaluated using pull-off test, and the results demonstrated that the adhesion strength of sample with higher content of urea and current density is about two times that of sample without PEO preparation.

The protective properties and adhesion strength of epoxy coating can be increased with PEO pretreatment.

The purpose of this paper is to study the electrochemical, mechanical and thermal characteristics of polyester – epoxy coating systems using electrochemical impedance spectroscopy (EIS), pull-off test and differential scanning calorimetry (DSC). These are very important properties to evaluate the performance of a coating system. Proper measurement and analysis techniques are needed for a proper evaluation of these properties to ensure the coating performance.

Different ratios of polyester and epoxy resins have been blended to formulate good anticorrosive, mechanically strong and thermally stable binder coating system. EIS, pull-off test and DSC were used to evaluate these properties.

The sample containing 90 wt.% polyester exhibited the best corrosion resistance from the beginning until the end of exposure time. The value of corrosion resistance (R_c) obtained on the 30th day of exposure was found to be 2.89 × 108 ohm cm⁻². The glass transition temperature (T_g) was found to be increasing with the incorporation of epoxy to the binder system. The result from pull-off test showed the best adhesion with the sample containing 90 wt.% polyester which also has the lowest T_g promoted better adhesion properties.

The curing time must be reduced for practical applications.

Hybrid coatings systems have been formulated. This paper discusses on the highest coating resistance obtained polymer-substrate mechanical properties and thermal characteristic of the polyester/epoxy binder resin using DSC.

In this work, the blends of poly(methyl methacrylate), PMMA and poly(methyl vinyl ether-alt-maleic acid monoethyl ester), PMVEMA-ES are studied as organic coatings to evaluate the impact of intermolecular hydrogen bonding on the physical and thermal characteristics of the prepared coatings.

PMMA (Mw = 120,000 g mol-1) was chosen as our binder material. Due to the low adhesion property of PMMA on polar substrates, it was blended with PMVEMA-ES, which contains polar –COOH groups, to improve the adhesion and thermal properties of the coatings by forming intermolecular hydrogen bonds. A cross-hatch adhesion test was carried out to evaluate the adhesion strength of different ratios of PMMA/PMVEMA-ES blends as coatings. In addition, changes in the glass-transition temperature, Tg as the composition varies were studied using Differential Scanning Calorimetry, DSC. Then, glossiness and hiding power tests were also conducted to evaluate the physical properties of the prepared coatings.

Upon a closer look at the DSC results, it was found that blends consisting of 12.5, 25.0 and 87.5 wt. % PMMA were completely compatible due to the presence of only a single Tg in their thermograms. Other blend compositions showed two distinct Tgs, indicating partial compatibility. Furthermore, the addition of PMVEMA-ES caused the Tg of PMMA to shift to lower temperatures, a strong indication of intermolecular hydrogen bonding interactions between the two components. From the cross-hatch adhesion results, the addition of PMVEMA-ES improved the adhesion properties of PMMA coating, except for blends consisting of 62.5 and 75.0 wt. % PMMA possibly due to the partial incompatibility between the two components. These findings were further corroborated with the results of glossiness and hiding power measurements. The superior result was seen for the blend consisting of 12.5 wt. % PMMA with strong adhesion property, high glossiness, compatibility and high translucency.

PMVEMA-ES can potentially be used as an adhesion promoter in PMMA-based coating formulations.

This is the first report on the properties of PMMA/PMVEMA-ES blends as coatings.

The anticorrosion coatings used in marine and atmospheric environment are subjected to many environmental factors. And the aging failure has been puzzling researchers. The purpose of this study is to find the correlation between the initial aging of epoxy coatings and the typical marine atmospheric environmental factors.

The epoxy coatings were subjected to a one-year exposure in three typical marine atmospheres. Meanwhile, principal component analysis, linear regression and Spearman and gray correlation analysis were applied to quantify the environmental characteristics and establish correlations with the coating aging.

The results indicate that the coating will undergo macroscopic fading and chalking upon exposure to the marine atmosphere, while microscopic examination reveals holes, cracks and partial peeling. The adhesion performance and electrochemical properties of the coating deteriorated with prolonged exposure, coating aging mainly occurs with the generation of O-H bonds and the breakage of molecular chains such as C-N and C-O-C. The coating was most deeply aged after exposure to the Xisha, followed by Zhoushan and finally Qingdao. Environmental factors affect the photooxidative aging and hydrolytic degradation processes of coatings and thus coating aging. To further demonstrate the correlation between environmental factors and coating aging, principal component analysis was used. The correlation model between environmental factors and coating aging was subsequently obtained. The correlation model between the rate of coating adhesion loss (E) and the comprehensive evaluation parameter of environmental factors (Z) is expressed as E = 0.142 + 0.028Z. Meanwhile, the Spearman correlation analysis and gray correlation method were used to investigate the impact of each environmental factor on coating aging. Solar irradiation, relative humidity and wetting time have the highest correlation with coating aging, which are all above 0.8 and have the greatest influence on coating aging; wind speed and temperature have the smallest correlation with coating aging, which are about 0.6 and have the least influence on coating aging.

This paper establishes a correlation between typical marine environmental factors and coating aging performance, which is crucial for predicting the service life of other coatings in diverse environments.

The purpose of this paper is to enhance the compatibility of titanium dioxide in epoxy resins and thus the corrosion resistance of the coatings.

In this work, TiO₂ was modified by the mechanochemistry method where mechanical energy was combined with thermal energy to complete the modification. The stability of modified TiO₂ in epoxy was analyzed by sedimentation experiment. The modified TiO₂-epoxy coating was prepared, and the corrosion resistance of the coating was analyzed by open circuit potential, electrochemical impedance spectroscopy and neutral salt spray test.

High-temperature mechanical modification can improve the compatibility of TiO₂ in epoxy resin. At the same time, the modified TiO₂-epoxy coating showed better corrosion resistance. Compared to the unmodified TiO₂-epoxy coating, the coating improved the dry adhesion force by 61.7% and the adhesion drop by 33.3%. After 2,300 h of immersion in 3.5 Wt.% NaCl solution, the coating resistance of the modified TiO₂ coating was enhanced by nearly two orders of magnitude compared to the unmodified coating.

The authors have grafted epoxy molecules onto TiO₂ surfaces using a high-temperature mechanical force modification method. The compatibility of TiO₂ with epoxy resin is enhanced, resulting in improved adhesion of the coating to the substrate and corrosion resistance of the coating.