Aluminum - Characteristics of Aluminum Alloy
1. Characteristics of Aluminum Alloy
1.
Advantages of Aluminum Alloy
Light
The specific weight of aluminum is 2.7, 1/3 of weight compared to iron (7.8) and copper (8.9)
Strong
The alloy can offer tensile strength ranging from 7 to 60 kg/mm2 depending on its type and through thermal refining. In addition, it increases strength under a super low temperature environment.
High corrosion resistance
The aluminum easily be oxidized in the air and form a layer of aluminum oxide on the surface. The aluminum oxide layer is superb in corrosion resistance and prevents its own corrosion.
High conductivity
The electrical conductivity is 60% of that of copper, at the same time, the weight is only 1/3 of that of copper. Thus twice of the conductivity is achieved with aluminum alloy compared against the copper when they are the same weight.
High processability
Aluminum has high plastic forming capability and allows to form a variety of shapes. By utilizing a special extrusion method, it is possible to make very complicated shapes easily.
No toxic property
Aluminum is a non hazardous material with no smell. High in sanitation. Thus often used for kettles and other kitchen/food related products.
Easy to recycle
It does not produce industrial waste. It can be recycled with only 3% of energy used for creating a new virgin metal.
2.
Corrosion of Aluminum Alloy
After a thin layer of aluminum oxide forms, aluminum alloy has high anti-corrosion performance. However, under some conditions, the corrosion types below can occur:

Contact Corrosion (Electric or Galvanic Corrosion)
When aluminum alloy is placed in conditions where a conductive solution while in contact with different types of metals with lower potential, the electrical potential difference causes galvanic corrosion of the aluminum alloy. It is also called electric or galvanic corrosion. The contact corrosion rarely occurs in dry air, however it could happen locally under the environment with presence of water content. It requires a special attention.
In order to avoid contact corrosion, always refer to the parts catalogue to choose the appropriate bolts, screws and nuts to be used together with aluminum alloy body parts and replace them where specified.
General Corrosion
Occurs when the protective natural aluminum oxide layer is destroyed by a chemical agent. Aluminum alloy will be corroded by both acid and alkali solutions.
3.
Oxide Layer
The melting point of the oxide layer is very high, at 4,532 °F (2,500 °C). The hardness and specific weight of oxide layer is higher than the aluminum alloy itself. The melting point of aluminum alloy is approximately 1,182 °F (640 °C).