Coated Panel

Based on the primers, two sets of coated panels ZP and ZR were taken for the experiments. Spray gnn was nsed to apply the coatings in a standard paint booth maintaining humidity and temperature. ZP system was coated with epoxy zinc 

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Whereas the eadiest fluorescent-dye pigments would last only 20 days outdoors in a screen-ink film, fade resistance has been improved to such an extent that some modem daylight-fluorescent coated panels stiU have useful color after nine months or mote in Florida sunlight in a 45° exposure tack facing south. The fluorescent layer is usually coated with an acrylic film containing a uv absorber. Indoor-accelerated exposure equipment is, of course, invaluable in the development of such systems. Better dyes and resins very likely will make possible fat mote stable coatings in the future. 

An example of the contribution of polar interactions between an acrylic PSA and a substrate is shown in Fig. 6. By copolymerizing iso-octylacrylate and acrylic acid, using a monomer ratio of, respectively, 95/5 and 90/10, two otherwise identical PSAs were made. The PSAs were laminated to both sides of a foam core to make an attachment tape as used in the automotive industry for the application of body side moldings to a car. One side of the foam tape was laminated against an aluminum foil backing. The other side was laminated against an automotive paint-coated panel to make the final test sample. The test sample was allowed to... 

Epoxy acrylate (Ebecryl 3700, 50%) combined with 25% TMPTA, 25% I BOA and with DIBF-OPPI-DIDMA pigment and FC-171 as above was also used to coat panels. These panels showed no removal of coating in the cross hatch adhesion test. With 6.8j there was no loosened coating on the frontal impact surface, and only 30% was loosened on the back surface. Five hundred grams were required to scratch to bare metal with the balanced beam. Performance was... 

When the epoxy coated panel containing artificial holidays was allowed to cathodically disbond, areas of greater than one square centimetre became detached in less than 7 days. Once again at no time were realistic A.E. transients observed. 

Initially, with the grey paint, it was thought that the thinness of the coating combined with its plasticity was causing the paint to peel from the surface in a ductile manner, it being further plasticised by the uptake of water. These observations were not true for the epoxy coated panels as the film thickness... 

Salt Spray Test Panels coated with the standard chromate conversion coating and CMT were compared with each other in their corrosion resistant properties in several ways. The conventional 5% NaCl/S02 fog chamber tests showed excessive corrosion and pitting within one week on chromate conversion coated (COC) 7075-T6 A1 alloy panels. The CMT coated panels were almost uncorroded and without any pits. The plates in Figure 1 show the conditions of the panels after 7 and 14 days exposure in this environment. Even after 14 days exposure the CMT panels were still far better than COC panels. 

Coating Stability The stability of a chemical conversion coating is best described by the non-leaching character of its corrosion inhibiting constituents and the insoluble nature of the oxides of the substrate metal. Chrcmate conversion coatings suffer from the lack of these properties. Thus, a study was conducted in which all the coated panels... 

Paints were prepared from polymers of different composition and composition distribution using a standard copper thiocyanate based formulation similar to that which has been described by Hails and Symonds (11). A rotating disc technique (3) was used to measure the polishing rate (which is a measure of hydrolysis rate) of polymer and paint films. Standard coated panels were attached to a disc (Figure 4) in a radial display and this disc then rotated at a constant speed (1400 rpm) in a thermostatically controlled lank (25°C) of replenished sea water. They hydrolytic stability of the films was assessed by the rate of change of film thickness as measured by a surface profiling technique (Ferranti Surfcom). 

Analogous oligomers were made from dodecanedioic acid (DDA, n=10) and for brassylic acid (BA, n=ll) for comparison studies. Resins made from the oligomeric diols derived from DDA and BA were made into similar coatings in which the diol/HMMM ratio was varied from 68/32 to 53/47 with p-TSA catalyst. The coated panels were baked at 133 °C for 15 min and, in the case of the n = 11 materials at 150 C for 30 min. Results are provided in Tables III and IV. 

The chemical resistance was measured by placing the coated panels into a 10% NaOH of HCl solution at room temperature for one week. 

To determine the wet bond strength coated panels were immersed in distilled water for 1500 h, removed and discs 25.4 mm in diameter stamped from them. The surfaces were wiped with a dry tissue and bonded between two cylindrical test pieces using a polyamide cured epoxide adhesive and immediately placed in a sealed container at 100% RH for the adhesive to cure. After 16 h the specimens were broken on an Instron Universal Test Machine with minimum delay. Recovered values were measured after the panels had dried out at room temperature and humidity for 7 days. Clearly, it is unlikely that the values reported represent the minimum bond strengths, as some drying out is almost inevitable, but the values are directly comparable. 

Corrosion performance was evaluated by the scab corrosion test. The coated panels were scribed and subjected to 25 cycles as follows 15 min immersion in 5% NaCl solution, 75 min air-dry at room temperature, followed by 22.5 h exposure to 85% relative humidity (RH) and 60°C environment. The tested samples were examined visually for failure such as corrosion, him lifting, peeling, adhesion loss, or blistering. The distance between the scribe line and the unaffected coating was measured as the corrosion creepage. 

Historically, conversion coatings have been evaluated by exposure testing, usually in a 5% salt fog. Corrosion resistance of conversion coated panels is deter-... 

Although the panel with the plasma deposited film followed by priming with E-coat is visually better, the use of the corrosion width provides a method for quantifying the improvement in the corrosion performance. Also the factor of about 2 difference in corrosion width between the two chromate conversion-coated panels is difficult to obtain from the qualitative difference observed from the scanned images. It can be seen from this comparison of three panels that the use of the measured corrosion width makes the differentiation of corrosion performance much easier. This method of evaluating corrosion test results is used to determine if the combination of the two bests could indeed yield the better corrosion protection of aluminum alloys. 

Scribed surface of E-coated panel with different surface pretreatments for corrosion testing... 

A nonchromated, water-borne primer applied to [2B] alloy samples, with the appropriate surface preparation and plasma deposition of an ultrathin plasma polymer, was also compared to controls prepared by depositing a chromated primer on chromate conversion-coated A1 substrate. The same comparison was also performed for IVD Al-coated 2024-T6 substrates (pure aluminum is deposited by ion vapor deposition process on aluminum alloy 2024-T6). In the latter case, the primer could not be removed from the IVD Al-coated panels that were treated with the plasma polymer prior to spray primer application. It is interpreted that the water-borne spray paint penetrates into the column structure of the top surface of the IVD Al-coated substrates when the surface energy was modified by the application of a plasma polymer. This effect could be viewed as interactive coating with a porous surface. 

When a test panel is subjected to an environment that is less corrosive, such as the Filiform test, the water sensitivity of the adhesion of a primer shows more clearly. In the Filiform test, scribed coated panels are exposed to HCl vapor for a... 

It is a well-established practice to test corrosion resistance of a coated panel by exposing a scribed coating layer to a corrosive environment such as salt spray for a prolonged period. Corrosion resistance of the coating is qualitatively evaluated by examining the corrosion that took place near the scribed line. Such a method certainly provides an estimate of the level of corrosion resistance of the coating however, this method does not yield information concerning the mechanisms of corrosion protection. 

T/F plasma polymer was also selected to improve the adhesion of different spray paints to IVD Al-coated panels. As presented in Table 32.3, T/F plasma polymer [DC plasma-polymerized trimethylsilane (TMS) followed by hexafluoroethane (HFE)] gave rise to such a strong adhesion of E-coat that could not be stripped off after 24-h application of Turco solution. Since the formation of mechanical interlocking between primers and porous IVD surfaces could conceal the role of plasma treatment in enhancing adhesion, bare 7075-T6 aluminum alloy panels with smooth surfaces were first used as substrate to examine the effect of plasma treatment on the adhesion of spray paints. 

Figure 32.3 shows the scanned images of SO2 salt spray-tested IVD Al-coated 7075-T6 panels one control, and two E-coated panels. The direct application of E-coat to IVD-coated panels (with no plasma treatment) did not provide corrosion protection as good as that of the chromate conversion oated control panel more corrosion creep from the scribed lines was observed on [7I]/E panels than on the [7pI]CC/E... 

It was noted (from Figure 32.14) that the [2I](0)/T/(Ar)/Dl specimen, which performed well in the SO2 salt spray test, exhibited much larger corrosion widths along the scribed lines, and much pit corrosion away from the scribed lines was visually observed after Prohesion test. The worse performance of Spraylat primer-coated samples likely resulted from its weaker adhesion to plasma-treated IVD surface than Dexter primer, which has been shown earlier from the adhesion test results. Another possible reason might be due to its inferior barrier properties to Dexter primer because there was no pit corrosion observed for Dexter primer-coated samples but many pits on Spraylat primer-coated panels after the Prohesion test. 

Figure 7.61 Cross-sections of plasma-sprayed hydroxyapatite layers (right) on Ti6AI4V substrates (far left). Panel (a) shows the as-sprayed hydroxyapatite coating together with a Ti02 bond coat. Panels (b)...

Bend test of coated panel over a 1-in. mandrel at 0 C pass pass pass ... 

Sample cells (Figure 5.16) were constructed upon the coated panels by glueing the polished end of glass tubes (internal diameter about 50 mm.) onto the coated surface with epoxy cement. The sample cells were stored at 22 2°C and a relative humidity of 55 + 5 per cent. The steel panel served as high potential electrode (H), and a mercury electrode, connected by a platinum wire, as low potential electrode (L). Guarding was achieved by using a bell-shaped brass cover which also supports the connector of the low potential electrode. 

Such coatings can significantly increase solar collector panel transparency and energy conversion efficiency.. That same coating reflects inefficient infrared radiation to prevent photovoltaic cell overheating and boost the energy conversion ratio. ITO coated panels are excellent conductors, and diminish the sheet resistance typical of thick silicon cells. 

Fig. 12, Calculated DMA. Degree of Cure for a Commercial Electrocoat System for Temperature Profiles Shown in Fig, 11, a, Standard Coated Panel, b. Wheel Stock Panel.

Oil paints solvent-lfee No. 665 standard oils, calcium carbonate, pigments, siccatives, lemon oil water-soluble exterior coating (paneling)... 

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