Surfing is a popular summer water sport. But do you know what material a surfboard is made of? Surfboards are mostly made of glass-fiber-reinforced aluminum-matrix composites, which are strong but less than pricey and recyclable. There is one material that can be called the best material for making surfboards-aluminum alloy. At present, foreign companies are developing all-aluminum surfboards.
According to foreign media reports, a surfboard company located in Utopic, Brittany, France, has been designing and manufacturing aluminum sandwich surfboards since 2020. According to the person in charge of the company, its bridge core hull box plate products are made of aluminum alloy and wood. The wood in it is an eco-friendly material from non-invasive fast-growing trees with a high rate of carbon dioxide absorption. And this kind of surfboard can be recycled in a closed loop, and the recycling capacity is much higher than the recycling rate of current polymer surfboards. The aluminum alloy surfboard has entered the test production stage in June 2021. It is foreseeable that the entry of aluminum alloy will bring great changes to the future of the surfing industry.
However, the aluminum alloy used to make surfboards also has its special requirements. Surfing is mostly carried out on the coast, and seawater is a strong corrosive medium, which puts forward high requirements on the corrosion resistance of materials. There is a layer of oxide film on the surface of aluminum and aluminum alloy, which makes the material have high corrosion resistance. Anything that can improve the compactness of the oxide film, increase the thickness of the oxide film, and improve the insulation performance of the oxide film will help to improve the corrosion resistance of aluminum and aluminum alloys. Conversely, any factor that reduces 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 alloys in alkaline solution and seawater descends 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 alloy. However, the above order of corrosion resistance is valid only when the alloys sensitive to exfoliation corrosion, intergranular corrosion or stress corrosion cracking are heat treated to remove these sensitivities, and at the same time, this order is not rigorous. According to this rough ranking, Al-Mg alloys, that is, 5000 alloys, have the strongest corrosion resistance to seawater. Therefore, the author recommends the use of Type 5083, Type 5054 and Type 5454 alloys for surfboards.
Among them, it is best to use 5454 type alloy, its typical physical properties at room temperature in various states are; /kg℃, (20℃～100℃) linear expansion coefficient 23.7×10-6. Physical properties of 5083-0 alloy: density 2.66g/cm3, melting temperature 579℃～641℃, electrical conductivity 29%IACS, The thermal conductivity is 117W/m℃, the specific heat is 900J/kg℃, and the coefficient of linear expansion (20℃～100℃) is 23.8×10-6.