Aluminum foil is a versatile and effective material, involving many applications, especially packaging and technical products. Some aluminum foil properties are common.
1. Environmental friendliness. Studies have shown that aluminum foil packaging and household aluminum foil account for less than 10% of the environmental impact in the product life cycle.
2. Strong barrier. Aluminum foil can block light, smell and moisture, while also protecting the smell or taste of the product.
3. Aluminum foil can reflect 98% of light and infrared rays. Bright surfaces also have low heat emissivity.
4. No stress, no closure. There are pinholes and wrinkles, so it is generally not used alone, usually processed into composite materials with paper and plastic films.
So first we should know the application of aluminum foil. There are many types of aluminum foil, we take food packaging and industrial use as examples.
Aluminum foil properties of food packaging. Aluminum foil is safe when in contact with food. Uncoated aluminum foil will not react with most foods; due to the high-temperature annealing process, aluminum foil is completely sterile and will not maintain or promote the growth of bacteria; it can be printed on aluminum foil, which is beautiful and provides anti-counterfeiting tamper-proof information. It is opaque and can protect easily melted food; aluminum foil has good plasticity, so it can be used to package products of various shapes.
There are many kinds of aluminum foil alloys, involving series 1,3,5,8 aluminum alloy. Series 1 alloys are pure aluminum alloys. Because of the high aluminum content, they are relatively soft and have good electrical conductivity. The 3 series alloy has added manganese, so it has increased anti-rust properties and its strength is higher than that of the 1 series alloy. It also has welding characteristics. The 5-series alloy adds corrosion resistance to the 3-series alloy. The 8-series alloy is added with al-fe-si element, and its alloy performance has a higher advantage in more than 1% of the total alloy elements.
The physical properties of aluminum foil are determined by itself. First, aluminum foil is a silver-like metal. It has a melting point of 660 ° c (1,220 ° f) and a boiling point of 2,327-2,450 ° c (4,221-4,442 ° f). The density is 2.708 g / cm3. Secondly, aluminum foil has toughness and ductility. Even if the thickness is very thin, it also has ideal tensile strength. Extensibility means that it can be folded into any shape and maintain this shape. Third, aluminum foil has good electrical conductivity. Although silver and copper have higher electrical conductivity, aluminum has a lower cost.
There is an interesting and very useful chemical properties of aluminum foil. In humid air, the aluminum foil surface slowly combines with oxygen to form alumina. Alumina forms a very thin whitish coating on aluminum foil. The coating prevents the metal from further reacting with oxygen and prevents the metal from further corrosion (rust). This characteristic is also the reason why aluminum foil and even aluminum products have corrosion resistance.
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