Salt spray test prohesion

Figure 28.8 Comparison of the two E-coat coated aluminum panels after Prohesion salt spray tests E-coats were removed after the test.

Figure 28.9 Comparison of chromated primer coated A1 panel ([7B](Dox)/T/F/A) with nonchromated primer coated A1 panel ([7B]y(Dox)/Tfs/(Ar)/X) after Prohesion salt spray test primers were removed after the test.

Two types of corrosion evaluation tests, SO2 and Prohesion salt spray tests, were employed for the evaluation of corrosion protection characteristics of painted plasma systems. The SO2 salt spray test was chosen to speed up differentiation of the corrosion protection properties of the different systems investigated. The Prohesion... 

Figure 31.18 Scanned images of Prohesion salt spray-tested (12 weeks) [2A] panels total scanned area 27 cm, total scribe length within the scanned area 16 cm the white spots on [2A] (Ace/0)/TN/E are paint which could not be stripped with Turco paint stripper (not pitting-corrosion sites).

E-coat stripping. Both plasma-treated panels show excellent corrosion protection performance as compared to the control panels. All [2A] panels with different plasma treatments and plasma polymer coatings, which were corrosion tested in both SO2 and Prohesion salt spray tests, were similarly scanned, and the corrosion width was evaluated by using a scanned image and computer calculation of the corroded area. Figure 31.19 compares the corrosion width obtained by the two methods. 

Figures 31.20 and 31.21 show the scanned images of SO2 and Prohesion salt spray-tested panels of [2B], respectively. Visual observation of these images reveals that panels that were only acetone wiped and E-coated ([2B](Ace)/E) provided poor corrosion resistance. In contrast, the plasma-modified [2B] panels showed excellent corrosion resistance even after 12 weeks of exposure to Prohesion salt spray,...

Figures 31.23 and 31.24 show typical scanned images of SO2 and Prohesion salt spray-tested [7B] panels, respectively. Visual observation of these images reveals that the plasma-modified panels of [7B] have outperformed both control panels in the SO2 salt spray test. These plasma film combinations were prepared on deoxidized [7B] surfaces without any plasma cleaning pretreatment. Figure 31.23 also shows an image of a panel that had simply been deoxidized prior to the application of E-coat, which performed excellently in the SO2 salt spray test. Figure 31.25 compares the corrosion width obtained by the two methods. The comparisons shown in Figures 31.19, 31.22, and 31.25 indicates that the results obtained by the two methods do not match, partly due to the different duration of tests, and that samples which show good results in one test do not do as well in the other test.

Prohesion salt spray-tested panels in Figure 31.24 show that [7B] (Alk/AH)/T/ E and [7B] (Alk/0)/TH/E systems performed comparably to the controls. Deft primer-coated control panels ([7B] CC/A) displayed extensive pitting corrosion away from the scribe in both tests, indicating that Deft primer may have poor barrier properties. This pitting corrosion away from the scribe was observed on both controls when examined by scanning electron microscopy (SEM). 

Figure 31.27 shows the comparison of average corrosion widths of (1) SO2 salt spray-tested and (2) Prohesion salt spray-tested A1 alloy panels and their corresponding control panels. After 4 weeks of SO2 salt spray test, most of the chromated primer-coated [2B] and [7B] panels, including those with excellent... 

Figure 31.27 Corrosion widths of (a) SO2 salt spray and (b) Prohesion salt spray-tested A1 panels with chromated plasma coating systems prepared by anode magnetron plasmas and their corresponding chromated controls.

Figure 31.30 Scanned images of Prohesion salt spray-tested A1 panels coated with nonchromated primers prepared in a flow or closed reactor system without using anode assembly Primer X could not be removed from plasma-treated [2P] and [7P] surface due to the strong adhesion.

The corrosion widths of Prohesion salt spray-tested IVD Al-coated Al panels were calculated and are summarized in Figure 32.6. As is evident from the data, after 12 weeks of Prohesion salt spray testing, IVD/plasma polymer/spray paint systems showed better corrosion protection overall than IVD/plasma polymer/E-coat systems. All the IVD/plasma polymer/spray paint systems outperformed the cathodic E-coated controls and showed corrosion test results comparable to those of the Deft primer oated controls. 

Figure 32.6 Average corrosion widths of Prohesion salt spray-tested IVD aluminum-coated 2024-T3 and 7075-T6 A1 panels, including chromated controls, IVD/plasma polymer/ E-coat, and IVD/plasma pol5uner/spray primer coating systems.

The corrosion widths of Prohesion salt spray-tested alloys are calculated and summarized in Figure 32.14. E-coated IVD controls (CC/E), i.e., the combination coating systems of chromate conversion coating with nonchromated E-coat, showed very large corrosion widths for all the IVD Al-coated aluminum alloys. This combination did not provide good corrosion protection, which could be taken as proof that the two completely different approaches (electrochemical corrosion protection and corrosion protection by barrier adhesion principle) should not be mixed. 

Figure 32.14 Corrosion widths of Prohesion salt spray-tested chromate-free plasma coating systems of IVD panels prepared under IVD conditions and their chromated controls.

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