Corrosion salt spray

Although most greases offer some inherent protection against msting, additives, eg, amine salts, sodium sulfonate, cycloparaffin (naphthenate) salts, esters, and nonionic surfactants (qv), are often used to provide added protection against water and salt-spray corrosion. A dispersion of sodium nitrite has been particularly effective in some multipurpose greases. 

Lack of lubrication. Exposure to salt spray, corrosive gases, alkaline water, acid water, mud, or dirt. Period of inactivity without adequate protection. 

The extent of coating adhesion failure was found to be dependent upon the resistance of the polymer in the coating to hydrolysis by corrosion generated hydroxide. In this study, similar trends have been observed for adhesives. Table I shows the results of salt spray corrosion on a series of bonds between cold rolled steel adherends and adhesives of varying chemistry. The results show that there is a direct correlation between the chemistry of the adhesive polymer and the durability of the series of adhesive bonds studied. The locus of adhesion failure also appears to be related to the type of adhesive chemistry. In this study, adhesives based on polymers having a wide range of hydrolysis resistance were examined. 

In general, paint adhesion and salt spray corrosion inhibition of iron phosphate coatings post-treated with polyvinylphenol derivatives have been equal to or superior to that obtained with chromate based systems. This has been the case particularly with many high solids paints. 

Figure 31.17 shows typical scanned images of SO2 salt spray-tested panels, two controls and two plasma polymer-treated panels. By visual observation, one can easily see that the corrosion performance of the plasma polymer-treated panels, [2A](Ace/0/N)/TN/E and [2A](Dox/AH)/TH/E, is far better than that of the control panels, [2A]CC/E and [2A]CC/A. Figure 31.18 shows typical scanned images of the surfaces of controls and plasma interface-engineered systems of [2A](Ace/0)/TH/E and [2A](Ace/0)/TN)/E after Prohesion salt spray corrosion testing and subsequent... 

Eugenija Ramoskiene Validation of salt spray corrosion test... 

Our aim was to present an experimental evaluation of the corrosivity of the salt spray corrosion test cabinet, to indicate the gaps in the description of the corrosion test method according to ISO 9227 and to estimate the main components of the uncertainty of the corrosivity measurement. 

Scientists (Ref 12) welded HSLA-65 using tungsten-base tools. Subjected to bend tests, a 10 mm (0.4 in.) thick weld passed, and a 6 mm (0.24 in.) thick weld failed when bent with the root in tension, due to the formation of surface cracks. Tensile properties of the 10 mm thick welds exceeded the specifications for the base metal. Some 6 mm thick welds exceeded the plate specifications, while others were approximately 10% below the plate specifications. Charpy V-notch (CVN) toughness at both -29 and 0 °C (-20 and 0 °F) were below the base material toughness but exceeded the minimum specification of the plate. The surface of the welded material was found to have small defects due to the roughness caused by the interaction between the shoulder and the surface of the plate. Salt spray corrosion tests indicated no preference for corrosion in the weld zone. 

For other coatings, aluminum vapor deposition (2-15 g/m ) was shown by Shin et al. (1992) to be more protective, thickness for thickness, on galvan-nealed substrates than on zinc-iron electroplating. At 2 g/m aluminum, salt spray corrosion resistance was five times better more meaningful tests were not conducted. The aluminum also resisted limited cycling to 500°C. 

Waldron, L., "Basic Requirements in the Standardization of the Salt Spray Corrosion Test," ASTM Proceedings, Vol. 44, 1944, pp. 654-662. 

FIG. 2—Effect of iron, nickel, and copper contaminant levels on ASTM B 117 salt spray corrosion rates In AZ91 alloy versus cold-rolled steel and 380 die cast aluminum [10,19]. 

Die-cast alloy AZ91 can give a salt-spray-corrosion performance that is good to excellent when compared with steel and aluminum (Hillis, 1983). The resistance of the high-purity alloy, for example AZ91E, is 10-100 times better than the standard purity alloy, and equal to or better than mild steel and the die-cast aluminum alloy 380 (Reichek et al., 1985 King, 1990). 

Figure 4-22. Iron-manganese solubility limits and the iron tolerance limit (Reichek et al., 1985) provides a guide to AZ91 corrosion performance. The numbers adjacent to the data points give the average salt spray corrosion rate (in mpy) of the die-cast samples.

Firm AN. Method of making the salt-spray corrosion test. Proceedings American Society for Testing of Materials 1918 18 237-8. 

Finn, A. N., Method of Making the Salt-Spray Corrosion Test, Proceedings of the American Society for Testing and Materials, 18 237—238 (1918). 

Neutral salt spray corrosion tests on coupons coated with the system without cerium compounds first showed evidence of corrosion after 170 h of exposure. After 336 h, both corrosion in the general area and sub-surface migration at the artificial scratch were clearly visible (Fig. 10.1). 

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