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MATERIALS SELECTION & DESIGN Analysis of Corrosion in Steel Cans in the Seafood Industry on the Gulf of California
TABLE 2
Effect of RH, temperature, and air pollution on the corrosion rate of steel in Guaymas, Sonora (2010)
SO2 Season
Spring Max Min
Summer Max Min
Winter Max Min
RH(A)
79.3 28.9
84.3 30.2
88.2 24.3
T(B)
22.1 15.1
34.6 24.3
25.6 17.3
C(C)
0.27 0.20
0.33 0.19
0.57 0.39
CR(D)
149.8 128.2
90.3 58.5
211.1 148.9
RH(A)
77.8 26.5
81.2 33.4
84.5 25.2
(A)RH%, (B)T—temperature (°C), (C)C—concentration level of air pollution, (D)corrosion rate (mg•m2 FIGURE 1 /y)
energy of 5 keV was applied to the clean surface of the metal specimens, which were analyzed with an ion beam with energy Ar+
of 0.3 µA/cm3
atmosphere.23 Results
With metal packaging, food can be Corrosion rate of steel cans in spring in Guaymas, Sonora (2010).
(AES) techniques to determine the air pollutants that react with the metallic surface exposed in the manufacturing process and warehouses. The quantitative and qualitative chemical analysis infor- mation was obtained using energy disper- sive x-ray analysis (EDXA) with the SEM.2
From the complete area of metal-
lic probes, a small fraction of 100 mm2 was cut and analyzed by SEM and AES in a chamber, with the lab technician using rubber gloves in both cases.21
SEM
was used to evaluate and determine the air pollutants on the surface of the steel cans, and AES was used to determine the corrosion products in the can layers. The piece was installed in the SEM chamber
54 MATERIALS PERFORMANCE April 2012
and then introduced to an ultra-high vacuum system. The examination in the vacuum chamber requires two steps: use of a mechanical oil pump to decrease the room pressure to 50 militorr and the use of a turbomolecular pump together with the mechanical pump to reduce the pres- sure to 1 nanotorr.22
With this technique,
the structural form and location of corro- sion can be quickly and accurately mea- sured, which helps to determine the type of corrosion and proper protection for the metals analyzed. AES was performed in Bruker Quantax†
and ESCA/SAM 560† models. A beam of electrons with an †Trade name.
distributed to the most remote places on the planet, and is preserved for long pe- riods of time without losing its nutritional properties. In coastal areas, where some food companies operate, atmospheric corrosion is a frequent problem for steel cans. Even with the implementation of techniques and methods of protection and the use of metal and plastic coatings, corrosion is still generated, being lower with the use of plastics.2
Controlling Climatic Factors Variations of RH in the range of 25 to 75% and temperatures from 5 to 30 ºC,
and the concentration levels of air pollut- IV\[ []KP I[ []TÅLM[ IVL KPTWZQLM[ M`KMML- ing the permitted levels of air quality standards increase the corrosion process. It is necessary to monitor and control the RH within an adequate range to avoid the generation of corrosion.
Corrosion Rate Analysis In the spring season (March to May),
at the beginning of the evaluation, the corrosion rate was from 5 to 130 mg•m2
/y NACE International, Vol. 51, No. 4
5 keV and a current density to remove CO2
from the Chloride (Cl– T(B)
26.7 17.1
34.5 21.3
26.7 12.8
) C(C)
292 149
161 107
312 211
CR(D)
155.6 123.2
107.8 78.9
213.2 154.6