Steel, cold-rolled corrosion protection

Steel objects, when exposed to humid atmospheres or when immersed in electrolytes, corrode at a rapid rate. For example, abrasively polished, cold-rolled steel panels will show signs of rust within 15 minutes when immersed in dilute chloride solutions with pH in the range of 7-10. One of the methods used to control this rapid corrosion is to coat the metal with a polymeric formulation such as a paint. The role of the paint is to serve primarily as a barrier to environmental constituents such as water, oxygen, sulfur dioxide, and ions and secondarily as a reservoir for corrosion inhibitors. Some formulations contain very high concentrations of metallic zinc or metallic aluminum such that the coating provides galvanic protection as well as barrier protection, but such formulations are not discussed in this paper. 

Parylene N to smooth surface materials has been reported with the application of plasma depositions [13,14]. It was reported that excellent adhesion of Parylene C coating to a cold-rolled steel surface was achieved using plasma polymer coatings, in turn giving rise to corrosion protection of the metal [15]. Another major deficiency of Parylene C is its poor painting properties when paint is applied on a Parylene C film, due to its extremely hydrophobic surface. Because of this, surface modification of Parylene films is necessary to enhance their adhesion performance with spray primers. 

Corrosion Protection of Cold-Rolled Steel and Pure Iron... 

System approach interface engineering (SAIE) by means of low-pressure plasma in corrosion protection of metals was first applied on cold-rolled steel (CRS) [1-3]. Unlike aluminum alloys described in the previous chapters, oxides on the surface of steel and iron are less stable than those on aluminum alloys, i.e., iron oxides formed on the surface do not have corrosion protecting capability of iron underneath and hence are more vulnerable for corrosion. On the other hand, the oxides on the surface of steel can be removed by plasma treatment, particularly of (Ar- -H2) plasma. Hence, SAIE could be performed in totally dry processes. The improvement of corrosion protection by means of environmentally benign process was the motivation for the approach. 

Carbon steel coated with zinc is known as galvanized steel, which protects the cold-rolled steel from corrosion in aqueous and high-temperature environments. Galvanized steel is used in laundry appliances as it provides resistance to laundry detergents. The cost of converting steel into the galvanized condition depends on the facility, but ranges between 50 and 100/metric ton of zinc. 

Uses Corrosion inhibitor for oil-, solv.-, or water-based coating systems provides corrosion protection for galvanized metal, phosphated steel, cold rolled steel... 

Although most studies of corrosion protection by conjugated polymers utilize the doped (thus conducting) form of the polymer, several studies have been conducted on neutral (undoped) polymers. Most of these studies have utilized the EB form of polyaniKne and include studies on A1 alloys [70,85,86], stainless steel [87], mild steel [88,89], cold rolled steel [90-92], carbon steel [93], and iron [92,94,95]. An undoped poly(2,5-bis(N-methyl-N-hexylamino) phenylene vinylene) or BAMPPV has been studied for the corrosion control of the A1 alloy AA 2024-T3 [96,97]. Little else appears to have been published on the use of other undoped conjugated polymers for corrosion control. 

It is known that conducting polymers provide beneficial protection to various kinds of metals in a corrosive environment [443-445]. Over the past decades, conducting polymers have been considered as the potential candidate for effective corrosion protection without the use of heavy metals. It was found that PPy-clay nanocomposites with low clay loading (e.g., 1.0 wt%) provided an enhanced corrosion protection effect on cold-rolled steel compared with pristine PPy [446]. Similarly, PANI-clay nanocomposites exhibited a better anticorrosion performance than conventional PANI [447]. In the... 

Silane adhesion promoters have been studied for the corrosion protechon of metal surfaces. The use of a silane in combinahon with a silane cross-linking addi-hve (Table 25.6) and with sulfur silanes (Table 25.14) have yielded very promising coating systems to replace the toxic chromates in steel [22]. Similar corrosion protection was realized on cold-rolled steel, iron, aluminum, and aluminum alloy surfaces by treatment with the same cross-linker system but in combination with aminosilanes in the admixture [23]. 

Sacrificial metals such as magnesium, zinc, and aluminum, are in the active region of the galvanic series and are extensively used for corrosion protection. The single largest application for cold-roll-bonded materials is stainless-steel-clad aluminum for automotive trim. The stainless steel... 

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