Method for manufacturing aluminum alloy exterior material for smart device
Provided is a method for manufacturing an aluminum alloy exterior material for smart devices which is formed not by extrusion or die casting but by a strip casting method using a rotating mold, and an aluminum alloy exterior material manufactured by the method. In accordance with an embodiment, the method includes: preparing a molten aluminum alloy; casting the molten aluminum alloy into a sheet shape using a rotating mold to form an aluminum alloy cast sheet; and anodizing the aluminum alloy cast sheet, wherein in the forming of an aluminum alloy cast sheet, X in Equation 1 below may have a value in the range of greater than 0 and equal to or less than 0.15. X =( W Zn +W Mg +W Cu +W Si )/TC <Equation 1> Here, W Zn +W Mg +W Cu +W Si is the total content (wt %) of zinc, magnesium, copper and silicon) in the aluminum alloy, and TC is the thermal conductivity (W/m·K) of the rotating mold.
1. A method for manufacturing an aluminum alloy exterior material for smart devices, the method comprising:
preparing a molten aluminum alloy;
casting the molten aluminum alloy into a sheet shape using a rotating mold to form an aluminum alloy cast sheet; and
anodizing the aluminum alloy cast sheet, wherein in the forming of an aluminum alloy cast sheet, X in Equation 1 below has a value in a range of greater than 0 to equal to or less than 0.15,
X =( W Zn +W Mg +W Cu +W Si )/TC(wt %/( W/m·K )) <Equation 1>
where W zn is the content (wt %) of the zinc (Zn) in the aluminum alloy, W Mg is the content (wt %) of the magnesium (Mg) in the aluminum alloy, W Cu is the content (wt %) of the copper (Cu) in the aluminum alloy and W Si is the content (wt %) of the silicon (Si) in the aluminum alloy, and where W Zn +W Mg +W Cu +W Si is the total content (wt %) of the zinc (Zn), magnesium (Mg), copper (Cu) and silicon (Si) in the aluminum alloy, and TC is the thermal conductivity (W/m K) of the rotating mold,
wherein the aluminum alloy cast sheet comprises a 6000 series aluminum alloy or a 7000 series aluminum alloy,
wherein the rotating mold comprises a copper twin roll, and
wherein the copper twin roll has thermal conductivity in a range of 200 W/m·K to 500 W/m·K.
2. The method of claim 1 , further comprising heat-treating the aluminum alloy cast sheet after performing forming of the aluminum alloy cast sheet.
3. The method of claim 2 , wherein the heat-treating comprises performing a solution treatment for 30 minutes to 10 hours at a temperature of 420° C. to 570° C.
4. The method of claim 3 , wherein the heat-treating further comprises, after performing the solution treatment, performing an aging treatment for 1 hour to 30 hours at a temperature of 100° C. to 250° C.
5. The method of claim 2 , further comprising cutting the aluminum alloy cast sheet after performing the forming of the aluminum alloy cast sheet.
6. The method of claim 1 , wherein the aluminum alloy cast sheet comprises:
zinc (Zn) in the range of 5 wt % to 10 wt %;
magnesium (Mg) in the range of 1 wt % to 4 wt %;
copper (Cu) in the range of greater than 0 wt % to 3 wt %;
silicon (Si) in the range of greater than 0 wt % to 0.5 wt %; and
the remainder being aluminum and inevitable impurities.
7. The method of claim 1 , wherein the aluminum alloy cast sheet comprises:
silicon (Si) in the range of greater than 0 wt % to 1.5 wt %;
magnesium (Mg) in the range of greater than 0 wt % to 1.2 wt %;
copper (Cu) in the range of greater than 0 wt % to 1 wt %;
zinc (Zn) in the range of greater than 0 wt % to 0.5 wt %; and
the remainder being aluminum and inevitable impurities.