in the design of parts, it is genarally a good idea to avoid region or points ofstress
concentration since these regions are susceptible to corroisn. give examples of the
things that can be done to avoid stress raisers.
salt(NaCl) is stored in an aluminiunm container.the container is used repeatedly in a
humid region.
(a) is there a possibility of cathodic and anodic reaction taking place?
(b) if yes, identify the reaction
Normally, aluminum forms a strong self protective oxide coating that prevents corrosion. Salt water disrupts this coating, and as a result, aluminum will localize corrosion and large pits will be seen in the aluminum.
To avoid stress raisers, which are points or regions of high stress concentration, in the design of parts, several measures can be taken:
1. Smooth Transitions: Use smooth, gradual transitions between different sections of a part to avoid sudden changes in geometry that can create stress raisers. For example, avoid sharp corners or sudden changes in cross-section.
2. Fillets and Blends: Incorporate fillets or blends at the junctions between different sections to distribute stress more evenly. These rounded or curved transitions help to reduce stress concentration.
3. Avoid Notches and Grooves: Notches, grooves, or sharp material discontinuities are stress raisers. Try to eliminate or minimize such features in the design.
4. Proper Material Selection: Select materials with good mechanical properties that can withstand the expected loads and stresses. Some materials are more prone to stress concentration than others.
5. Correct Dimensioning and Tolerancing: Ensure that parts are dimensioned and toleranced properly to minimize stress concentration. Avoid unnecessary tight tolerances that may result in stress concentration.
Now, let's address the specific questions related to the aluminum container storing salt in a humid region:
(a) Yes, there is a possibility of cathodic and anodic reactions taking place when salt (NaCl) is stored in an aluminum container in a humid environment.
(b) The specific reactions that can occur are:
Cathodic Reaction: Reduction of oxygen (O2) present in the humid environment at the aluminum surface:
O2 + 4H2O + 4e- -> 4OH-
Anodic Reaction: Oxidation of aluminum (Al) to form aluminum ions:
2Al -> 2Al3+ + 6e-
These reactions can lead to the corrosion of the aluminum container when salt and moisture are present.