Surfing is a popular summer water sport. But do you know what surfboards are made of? Most surfboards are made of fiberglass reinforced aluminum-based composites, which are strong but not as expensive or recyclable. One of the best materials for surfboards is aluminum alloy. At present, foreign enterprises are developing all-aluminum surfboards.
Utopik, a surfboard company based in Brittany, France, has been designing and manufacturing aluminiumsandwich surfboards since 2020. The company said its bridge core hull plate products are made of aluminum alloy and wood. The wood is an eco-friendly material from non-invasive, fast-growing trees that absorb carbon dioxide at a high rate. And the surfboard can be recycled in a closed loop, far more than the recycling capacity of current polymer surfboards. The aluminum alloy surfboard entered test production in June 2021. It can be foreseen that the entry of aluminum alloy will bring great changes to the future of surfing industry.
However, the aluminum alloy used to make surfboards has its own special requirements. The sea water is a kind of strong corrosive medium, which puts forward a high requirement on the corrosion resistance of materials. Aluminum and aluminum alloy surface has a layer of oxide film, so that the material has a high corrosion resistance. All can improve the density of oxide film, increase the thickness of oxide film, improve the insulation performance of oxide film, will help improve the corrosion resistance of aluminum and aluminum alloy. Conversely, all factors that reduce the effectiveness of the oxide film, whether mechanical or chemical, will make the corrosion resistance of aluminum and aluminum alloy sharply decreased.
The corrosion resistance of aluminum alloys 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 alloy. However, this order of resistance holds only when the alloys sensitive to spalling, intergranular, or stress corrosion cracking have been heat treated to remove these sensitivities, and this order is also lax. In this rough order, the Al-Mg alloy, or 5000 alloy, is the most resistant to seawater. Therefore, the authors recommend the use of type 5083, 5054 and 5454 alloy surfboards.
Among them, it is best to use 5454 alloy, whose 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℃, linear expansion coefficient 23.7×10-6 (20℃ ~ 100℃). Physical properties of type 5083-0 alloy: density 2.66g/cm3, melting temperature 579℃ ~ 641℃, conductivity 29%IACS, thermal conductivity 117W/m℃, specific heat 900J/kg℃, linear expansion coefficient 23.8×10-6 (20℃ ~ 100℃).
