Steel test panels

Figure 7. Paint adhesion loss in salt spray exposure (ASTM B117) as a function of ester content for chain-extended epoxy-amine and epoxy-ester resin based coatings. All coatings applied at 20-25 urn film thickness to SAE 1010 steel test panels, baked, scribed and exposed for 24 hours to salt spray conditions.

Figure 3. Effect of EME 58 (58 wt% mercaptoester units co-polymer) coupling agent concentration on the peel strength of flexible epoxy (amine-cured)/AD = acetone-degreased steel test panels following (a) I day and (b) 3 day exposure to 57°C condensing humidity. See Appendix 4 for epoxy resin and cure description.

Effect of the coupling agent mercaptoester concentration on the peel adhesion and corrosion protection of epoxy/EME/steel test panels [7]... 

Radiation Curing. Samples to be Irradiated were coated onto either Bonderite-40 treated steel test panels (Parker Chemical) or polyethylene coated paper board. An excess of the sample was placed at one end of the substrate and a 6 wire wound rod was drawn across the substrate with even pressure pushing excess material off the edge. This method produced coatings with a thickness of 6 to 12 um. 

Most of the testing we did early on was pretty simple. There are three basic properties of all pressure-sensitive adhesives peel, tack and shear. Most of the testing we did was pretty limited to peel adhesion tests, tack tests and shear tests. We weren t doing a lot of application-related testing. Testing was done in lab conditions on stainless steel test panels, and customers were trying to translate that information into whether the adhesive would actually perform on their specific substrate. 

The reproducibility of test results between labs using the neutral salt spray tests has not been consistent, but the repeatability, within one lab, is better, and the test has value in comparing variations in coating systems. Correlation of hours of exposure in the salt spray test to actual performance of the plated part in service, even in marine atmospheres, is not consistent and usually avoided. A classic example is that cadmium deposits outlast zinc deposits on steel in salt spray tests and clean marine atmospheres, yet zinc outlasts cadmium when exposed to real, industrial atmospheres, because of the presence of sulfur-bearing corrodents in industrial environments. An important variable in salt spray testing is the position of the surface to be tested. Whereas the surface of test panels is specified to be 15—30° from the vertical (40), when salt spray testing chromated zinc-plated specimens, this range has appeared excessive (41). 

This test measures the ability of a tape to resist creep under applied load. The test is covered in ASTM D-3654 and PSTC-7. A specified area (typically 12.7 mmx 12.7 mm) of conditioned tape is rolled down with a specified pressure on the substrate of choice, such as polished 302 stainless steel. The panel is fixed in the vertical position or up to 2° tilted back so that there is no element of low angle peel in the test (Fig. lb). A weight (often 1000 g) is fixed to the end of the tape and the time to failure, i.e. complete detachment from the plate, is measured. Infrequently, the time required for the tape to creep a given distance is measured and reported. 

Test Panel Preparation. Grit-blasted, steel Q-panels, 3 x 5 in were stored in protective paper inside a desiccator. Just prior to use they were rinsed with a 1/1 (by volume) mixture of mineral spirits and methyl ethyl ketone, allowed to dry, then rinsed with methyl ethyl ketone. Coatings were applied with a brush and thinned to uniform thickness with a number 24 helically wound (Meyer) rod. 

All resins except polybutadiene formulated with conventional melamine cross-linkers, applied to SAE 1010 bare steel paint test panels, and baked to yield cross-linked, solvent resistant films. 

Figure 6. Influence of EME co-polymer coupling agent mercaptoester unit concentation on (a) the dry peel strength and (b) the time in 57 C water until the presence of visible corrosion products was observed for epoxy/steel peel test panels. From ref. 6.

Figure 10. Peel strength durability in a 5TC condensing humidity of acetone-degreased and EME 67 (67 wt% mercaptoester unit copolymer) coupling agent treated 1010 carbon steel/epoxy peel test panels. The epoxy top-coat formulation is given in Appendix 4.

The heat transfer through the same composition mastic by flame temperature of 2000 F. directed against it is illustrated by three test panels of steel 3/16 inch thick and 12 inches square. One panel was soated with 9/16 inch of mastic, and the second bad steel wire lath welded on a five points and then covered with 1/2 inch of mastic the third panel was left bare. The source of fire for the tests was a large gas burner with forced air feed. Temperatures of the heat source and heat transfer on the uninsulated side were made with the thermocouple. The results of the fire test were as... 

At exposure of steel in heavily polluted industrial atmosphere the corrosion rate on the upper side of steel panels exposed at 45° inclination was only 37 per cent of the total corrosion. In clean air, by contrast, the corrosion effect of rain was predominant and the upper sides of the test panels corroded faster than the undersides ( 6). The atmospheric corrosion of steel proceeds in local cells, where the sulphate nests acts as anodes. This may be the explanation why the washing effect of rain prevails in polluted atmospheres, as rain water may wash away sulphates from the nests. 

A series of laboratory experiments was conducted in which galvanized steel samples were exposed to NO2 in air and irradiated propylene/nitrogen oxides/air mixtures in the absence and presence of SO2. Dew was produced periodically on the test panels, and, at the end and/or during the experiments, panels were sprayed with either deionized water or an ammonium bisulfate solution (pH of 3.5). Gas phase concentrations were monitored, and dew and rain rinse samples were analyzed for nitrite, nitrate, sulfite, sulfate, formaldehyde, and zinc. 

In the winter of 1984-1985, test samples on Plexiglass plates were exposed in each of the test cities. These included samples of bare weighed auto-body steel, weighed galvanized steel, and painted auto-body steel with stainless steel trim. Where painted panels were involved, cut edges were coated in the stainless steel trimmed panels, the ends of the stainless steel bolts used for electrical continuity were coated as well. Nylon bolts were used to attach the other test specimens to the Plexiglass plate which was mounted on the front bumper of an automobile. 

Maruthamuthu, S., Eashwar, M., Manickam, S.T., Ambalavanan, S., Venkatachari, G. and Balakrishnam, K., 1990, Marine fouling on test panels and in-service structural steel. Tuticorin Harbour, Indian J. Marine Sci., 19, 68, 0, 70. 

Peel Test (PSTC-1) - Cold rolled steel "Q-Panels" (Q-PanelCo.) were used. A one-inch wide strip of coated Mylar is bonded to the panel under pressure of a 4 1/2-lb. roller. 

Bird applicator n. Device used for the laboratory application of coating of a prescribed thickness to test panels. It is a machined steel bar with a fixed clearance having a beveled undercut to guide the coating material. 

Racks were made as per standard [12, 13] using mild steel angles and channels with height and width (1.50 x 2.10 m ). The racks were coated with epoxy paint to prevent rusting. Porcelain washers, brass nuts and bolts were used to fix the test panels at 45° with respect to base. Three types of test panels uncoated, coated and scribed coated were fixed in the racks and test racks at three exposure sites are shown in Figs. 2.6a, b and c. 

An extensive range of bimetallic couples was studied by Southwell et al. (1976) in Panama, including zinc in contact with various types of steel in seawater and fresh water. The numerical results depend of course on the relative size of the test panels, but it is interesting to note that the zinc in these bimetallic couples in seawater corroded 25 times as fast as uncoated zinc. 

The benefits of a duplex coating are achieved only if there is good, long-lasting adhesion of the paint to the zinc coating. The NMP (A(-methyl-pyrrolidone) test has been described by Van Ooij et al. (1982). The test panels are immersed in the heated solution at 60 C (Fig. 1.16) and the time before the paint lifts is measured. Figure 1.17 shows the use of this test to demonstrate how silanes increase adhesion of an automotive epoxy-polyurethane primer to galvanized steel. 

The International Organization for Standardization Technical Committee on Corrosion of Metals and Alloys, ISO/TC156, has developed a systematic approach to chissifi-cation of atmospheric corrosivity [13], This approach is based on two different methods. The first method involves exposure of standard coupons of steel, zinc, copper, or aluminum to the atmosphere at the site where the classification is to be made. The selection of which metal is to be used will depend on the purpose of the test. Panels are... 

Rommal, H, E. G., Lawson, K M., Tiburdo, A. C., and Lawsm, H. H., Accelerated Test Development for Coil-Coated Steel Building Panels, Paper 356, CORROSION 98, NACE International, 1998. 

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