Surfing is a popular summer water sport. But do you know what material the surfboard is made of? Surfboards are mostly made of glass fiber reinforced aluminum matrix composites. Although this material has high strength, its price and recyclability are not satisfactory. One kind of material can be called the best material for making surfboards - aluminum alloy. At present, foreign enterprises are developing all aluminum surfboards.
A surfboard company in France has been designing and manufacturing aluminum sandwich surfboards since 2020. The person in charge of the company said that its Bridge Core hull box plate products are made of aluminum alloy and wood. Among them, wood is eco-friendly material, which comes from non-invasive and fast-growing trees and absorbs carbon dioxide at a high rate. And this kind of surfboard can be recycled in a closed circuit, and the recovery capacity is much higher than the recovery rate of the current polymer surfboard. The aluminum alloy surfboard has entered the test production stage in June 2021. It can be predicted that the entry of aluminum alloy will bring great changes to the future of surfing industry.
The aluminum alloy used to make surfboards also has special requirements. Surfing is mostly carried out in the coastal area. Seawater is a strong corrosive medium, which puts forward high requirements for the corrosion resistance of materials. Aluminum and aluminum alloy have a layer of oxide film on the surface, which makes the material have high corrosion resistance. Anything that can improve the density of the oxide film, increase the thickness of the oxide film and improve the insulating property of the oxide film will help to improve the corrosion resistance of aluminum and aluminum alloys. On the contrary, any factors that reduce the effectiveness of the oxide film, whether mechanical or chemical, will sharply reduce the corrosion resistance of aluminum and aluminum alloys.
The corrosion resistance of aluminum alloy in alkaline solution and seawater decreases in the following order: Al Mg alloy, industrial pure aluminum, Al Mn alloy, Al Mg Si alloy, Al Zn Mg alloy, Al Si alloy, Al Zn Cu Mg alloy, Al Cu Mg alloy, Al Cu Mg alloy and Al Cu alloy. However, the above-mentioned arrangement of corrosion resistance can be established only when the alloys sensitive to exfoliation corrosion, intergranular corrosion or stress corrosion cracking are heat treated and these sensitivities are removed. At the same time, this arrangement is not rigorous. According to this general order, Al Mg alloy, i.e. 5000 alloy, has the strongest corrosion resistance to seawater. Therefore, it is recommended to use 5083, 5054 and 5454 alloys to make surfboards.
Among them, 5454 alloy is preferred, and its typical physical properties at room temperature in various states are:; Density: 2.69g/cm3, melting temperature: 602 ℃ ~ 646 ℃, conductivity: 34% IACS, thermal conductivity: 134w / m ℃, specific heat: 900j / kg ℃, (20 ℃ ~ 100 ℃) linear expansion coefficient: 23.7 × 10-6.
Physical properties of 5083-O alloy: density 2.66g/cm3, melting temperature 579 ℃ ~ 641 ℃, conductivity 29% IACS, thermal conductivity 117w / m ℃, specific heat 900j / kg ℃, linear expansion coefficient (20 ℃ ~ 100 ℃) 23.8 × 10-6.
