KR100961081B1 - Zinc-aluminium alloys with high strength and low density - Google Patents

Abstract

PURPOSE: A high strength lightweight zinc-aluminum alloy is provided to reduce the weight by 18% by adding the alloying element and to increase the intensity by 20%. CONSTITUTION: A high strength lightweight zinc-aluminum alloy is made from aluminum 47~52 weight%, copper 2.0~3.0 weight%, silicon 0.001~ 3.0 weight%, and the rest of zinc. The high strength lightweight zinc-aluminum alloy includes element 0.001~2.0 weight% more than one or two selected in the group consisting of the titanium, beryllium, magnesium, nickel, vanadium, tin, iron, chrome, zirconium, strontium, scandium, manganese.

Description

Zinc-aluminium alloys with high strength and low density}

The present invention relates to a high strength lightweight zinc-aluminum alloy, and more particularly, 45 to 55% by weight of aluminum (Al), 1.0 to 9.0% by weight of copper (Cu), 0.001 to 3.0% by weight of silicon (Si), and the balance of zinc. It relates to a zinc-aluminum alloy composed of (Zn).

Today, die casting technology has been developed to produce high quality products. However, the quality of the die casting can vary greatly depending on the machine and the chosen process, as well as the chemical composition and structure of the alloy used. The latter two parameters are known to influence the castability, feed behavior, mechanical properties and, in particular, the life of the casting tool, which is important in die casting.

In the past, little attention has been given to the development of alloys suitable for die casting parts such as exterior materials and hinges of notebooks or mobile phone cases. However, as the product becomes complicated in appearance and function, there is an increasing need to develop die casting alloys that can withstand more deformation. In addition, in the case of portable electronic products such as laptops or mobile phones, the weight reduction and the miniaturization are directly related to the competitiveness of the product, and for this, it is necessary to develop lighter materials while providing sufficient strength for product protection. In particular, parts that support the LCD panel portion, parts such as a thin, complex hinge, etc. need a high strength alloy.

As a non-ferrous metal alloy used in cases and brackets of electronic products, alloys mainly composed of magnesium and aluminum are used, but magnesium has a high risk of ignition due to its intrinsic properties, and its electrochemical negativeness is higher than that of other metal elements. When copper, nickel, or silicon precipitates as small particles in the form of an intermetallic compound in the base, an electrochemical corrosion occurs easily at the interface by forming a cathode as compared to the base. In particular, even if a very small amount of iron is added to an alloy containing magnesium as a main component, the corrosion resistance of the alloy is greatly reduced. Natural coatings formed on the surface of magnesium also have significant passivation properties and are often basic and therefore weak to the surrounding environment and require surface treatment. Therefore, it is not preferable to use it as a main component.

On the other hand, when manufacturing parts requiring high strength, zinc die casting alloys of high strength have been used rather than aluminum die casting alloys. Typical zinc die casting alloys are Zamak alloys, which typically contain 4% by weight of aluminum and are excellent in castability. ZA27, which has an aluminum content of up to about 27% by weight, has a high tensile strength but has a heavy density of about 4.9 g / cm 3. In order to manufacture components of portable electronic products that require high strength but light characteristics such as exterior materials and hinges of portable notebooks or mobile phone cases, lightweight high strength die casting alloys are required.

The inventors of the present invention have found that the density of the alloy decreases when the ratio of aluminum is drastically increased compared to the existing zinc-aluminum alloy while studying safe and high strength and light die casting alloy. However, if the height is too high, there is a problem that the strength of the product is greatly reduced, and after repeated studies, the present invention completed the optimum ratio.

Therefore, an object of the present invention is 45 to 55% by weight of aluminum (Al), 1.0 to 9.0% by weight of copper (Cu), 0.001 to 3.0 of silicon (Si) It is to provide a zinc-aluminum alloy composed of weight%, the balance of zinc (Zn).

Another object of the present invention is titanium (Ti), beryllium (Be), magnesium (Mg), nickel (Ni), vanadium (V), tin (Sn), iron (Fe), chromium (Cr), zirconium (Zr) , One or two selected from the group consisting of strontium (Sr), scandium (Sc) and manganese (Mn)), 0.001 to 2.0 wt% of elements, 45 to 55 wt% of aluminum (Al), and 1.0 to 9.0 of copper (Cu) It is to provide a zinc-aluminum alloy composed of weight percent, 0.001 to 3.0 weight percent of silicon (Si) and the balance of zinc (Zn).

In order to achieve the above object, the present invention provides an alloy comprising 45 to 55% by weight of aluminum (Al), 1.0 to 9.0% by weight of copper (Cu), 0.001 to 3.0% by weight of silicon (Si), and a balance of zinc (Zn). Provides an aluminum alloy.

In order to achieve another object of the present invention, titanium (Ti), beryllium (Be), magnesium (Mg), nickel (Ni), vanadium (V), tin (Sn), iron (Fe), chromium (Cr), zirconium 0.001 to 2.0 one or more elements selected from the group consisting of (Zr), strontium (Sr), scandium (Sc), and manganese (Mn) A zinc-aluminum alloy is provided which is composed of weight percent, 45 to 55 weight percent of aluminum (Al), 1.0 to 9.0 weight percent of copper (Cu), 0.001 to 3.0 weight percent of silicon (Si) and the balance of zinc (Zn).

Hereinafter, the present invention will be described in detail.

In order to form the alloy according to the invention, aluminum, copper, silicon and zinc are first mobilized.

When the content of aluminum is less than 45% by weight, the density of the alloy does not decrease much, and when it exceeds 55% by weight, the strength is greatly reduced. Therefore, in the present invention, the aluminum content is limited to 45 to 55% by weight. More preferred aluminum content is 47 to 52% by weight, most preferably 49 to 51% by weight.

Copper is an element added for strength improvement. However, if the content is increased, the brittleness is increased, the mechanical properties are degraded, and since it is a heavy element, it does not help to reduce the density. Therefore, in the present invention, the copper content is limited to 1.0 to 9.0 wt%. More preferred content of copper is 2.0 to 7.0% by weight, most preferably 2.0 to 3.0% by weight.

Silicon is involved in improving castability and mechanical properties in cast aluminum alloys. However, if more than 3.0% by weight of the alloy increases the brittleness of the alloy to decrease the mechanical properties, so when the product is separated from the mold during the die casting process, there is a problem that the product is broken in the present invention, the silicon content of 0.001 to 3.0 Limited to weight percent. More preferred content of silicone is 0.01 to 2.0% by weight, most preferably 0.1 to 1.0% by weight.

Meanwhile, one or more elements selected from the group consisting of titanium, beryllium, magnesium, nickel, vanadium, tin, iron, chromium, zirconium, strontium, scandium and manganese, aluminum, copper, and silicon in order to form another alloy according to the present invention And zinc are mobilized.

In addition, the addition of a small amount of titanium and beryllium increases the ductility without reducing the strength to improve the toughness, but the addition of a large amount of titanium becomes brittle, beryllium is a strong toxicity element in the present invention is 0.001 to 2.0% by weight Limited to inclusion. More preferably limited to 0.001 to 1.0% by weight.

In the embodiment of the present invention, as shown in Table 1, the alloy piece using the alloy of the composition of the present invention to produce an alloy piece having a composition outside the composition range of the present invention and the alloy piece having a known composition and uniaxial tensile, three-point bending Comparative tests were performed.

As a result, as shown in Table 2, it was confirmed that the alloy of the present invention has a higher tensile strength and a higher bending force than other alloys while having a lower density than a known alloy. In addition, when adding a small amount of titanium and beryllium it was confirmed that the stretching force increases.

Accordingly, the present invention provides an alloy having a lower density and a higher strength than conventional zinc-aluminum alloys. The alloy of the present invention is a high-strength lightweight zinc-aluminum alloy that is 18% lighter than the existing zinc-aluminum alloy and has a strength of 20% or more, so that the durability and weight of the product can be realized. have.

Hereinafter, the present invention will be described in detail by way of examples.

However, the following examples are illustrative of the present invention, and the present invention is not limited to the following examples.

<Examples 1 to 4>

Production of test alloy pieces

After preparing the raw materials in the ratio of Example 1 to Example 4 and Comparative Examples 1 to 5 of Table 1, each of the actual mobile phone case manufactured by the die casting method by dissolving the uniaxial tensile test and three-point bending test The density was measured according to the method of KS M 0602.

As a result, it was confirmed that the density of the alloy of the present invention (Examples 1 to 4) was about 18% lower than that of the ZA27 alloy.

Alloy Composition and Density of Examples and Comparative Examples Alloy symbol Alloy composition Density (Approx.) Zn Al Cu Si Etc Example 1 Alloy 1 Bal. 49.3 3.0 0.1 4.0 g / cm 3 Example 2 Alloy 2 Bal. 50.2 2.8 0.5 Ti: 0.05 3.9 g / cm 3 Example 3 Alloy 3 Bal. 49.9 2.8 0.5 Ti: 0.5 3.9 g / cm 3 Example 4 Alloy 4 Bal. 50.9 2.9 0.5 Ti: 0.05, Be: 0.05 3.9 g / cm 3 Comparative Example 1 ZA27 Bal. 28.2 2.0 - 4.9 g / cm 3 Comparative Example 2 Comp 1 Bal. 55.5 3.0 0.5 3.7 g / cm 3 Comparative Example 3 Comp 2 Bal. 50.1 0.4 0.1 3.9 g / cm 3 Comparative Example 4 Comp 3 Bal. 48.8 9.5 2.0 4.1 g / cm 3 Comparative Example 5 Comp 4 Bal. 48.5 3.0 4.0 3.8 g / cm 3

Experimental Example 1

Uniaxial Tensile Comparison Test of Alloy Pieces

The uniaxial tensile test was performed on the alloy of Table 1 at a speed of 1.5 mm / min based on KS B 5521 and KS B 0802.

As a result, as shown in Figure 1, the tensile strength of the zinc-aluminum die-cast alloy according to Examples 1 to 4 is a general zinc die casting alloy Comparative Example 1, Comparative Example 2 with a high content of aluminum and less copper content It confirmed that it was larger than the tensile force of Example 3. In addition, as shown in Table 2, in the case of Comparative Example 4 with a large amount of copper, it can be seen that there is no significant difference in comparison with Comparative Example 1 in which the tensile force is a general die casting alloy. In the case of Comparative Example 5 having a large amount of silicon, the specific gravity was small, but the brittleness of the alloy was large, indicating that fracture occurred before sufficient deformation occurred. Therefore, the mechanical properties of the zinc-aluminum die casting alloy according to the preferred embodiment of the present invention was confirmed to be superior to the alloy of the comparative example.

Alloy Mechanical Properties of Examples and Comparative Examples Alloy symbol Tensile test Bending test Tensile force Deformation length Bending force Deformation length Example 1 Alloy 1 3536 N 1.71 mm 155.0 N 7.40 mm Example 2 Alloy 2 3620 N 1.46 mm 160.7 N 6.41 mm Example 3 Alloy 3 3881 N 1.80 mm 166.8 N 7.43 mm Example 4 Alloy 4 3920 N 1.87 mm 166.8 N 11.59 mm Comparative Example 1 ZA27 3104 N 2.10 mm 130.0 N 12.38 mm Comparative Example 2 Comp 1 2238 N 1.00 mm 94.3 N 8.38 mm Comparative Example 3 Comp 2 2756 N 1.25 mm 120.6 N 7.63 mm Comparative Example 4 Comp 3 3274 N 1.39 mm 136.1 N 6.74 mm Comparative Example 5 Comp 4 2511 N 0.62 mm 117.5 N 1.05 mm

Experimental Example 2

3-point bending comparison test of alloy pieces

The three-point bending test was performed on the alloy of Table 1 at a speed of 60 mm / min based on KS B 0804.

As a result, as shown in Figure 2, the bending test also obtained similar results to the tensile test results. It can be seen that the bending force of the zinc-aluminum die-casting alloys according to Examples 1 to 4 is larger than that of the comparative example, and Examples 1 to 2 and 4 to which titanium and berylnium are not added. Comparing the results, it was found that addition of a small amount of titanium and addition of titanium and beryllium increased both the amount of bending deformation and the bending strength of the alloy. Therefore, it was confirmed that the addition of a small amount of titanium or titanium and beryllium to the zinc-aluminum die casting alloy improves the toughness of the alloy.

The present invention can be industrially useful by presenting a high strength lightweight zinc-aluminum die casting alloy that is about 18% lighter than conventional zinc die casting alloys and has improved strength by more than 20% due to the proper addition of alloying elements.

Experimental Example 3

Structure observation of alloy piece

3 and 4 show optical microscope observation structures of the alloy of the present invention (Example 2) and the known alloy (ZA27). In general, it is known that the strength of the alloy having a fine structure is high. It can be seen that the alloy structure of the present invention is finer than that of the known alloy, which is consistent with the alloy strength of the present invention being larger than the known alloy. Moreover, it turns out that the alloy of this invention is also large in the fraction of a 2nd phase (black part). Therefore, due to the fine structure and the large fraction of the secondary phase, it can be explained that the strength of the alloy of the present invention is larger than that of the known alloy.

As described above, the present invention provides an alloy having a lower density and a higher strength than the existing zinc-aluminum alloy. The alloy of the present invention is a high-strength lightweight zinc-aluminum alloy that is 18% lighter than the existing zinc-aluminum alloy and has a strength of 20% or more, so that the durability and weight of the product can be realized. There is high industrial applicability.

1 is a result of comparing the uniaxial tensile test of zinc-aluminum alloys according to Examples and Comparative Examples of the present invention (Force: tensile force, extension: strain length).

2 is a comparison result of the three-point bending test of the zinc-aluminum alloy according to the Examples and Comparative Examples of the present invention (Force: bending force, extension: deformation length).

3 is an optical microscope structure of an alloy of the present invention (Example 2).

4 is an optical microscope structure of a known alloy (ZA27).

Claims (9)

High strength lightweight die-casting zinc-aluminum alloy composed of 47 to 52 wt% of aluminum (Al), 2.0 to 3.0 wt% of copper (Cu), 0.001 to 3.0 wt% of silicon (Si) and the balance of zinc (Zn). delete The high strength, lightweight die-cast zinc-aluminum alloy of claim 1, wherein the aluminum is 49-51 wt%. delete delete The high strength, lightweight die-cast zinc-aluminum alloy of claim 1, wherein the silicon is 0.01-2.0 wt%. The high strength, lightweight die-casting zinc-aluminum alloy of claim 1, wherein the silicon is 0.1 to 1.0 wt%. Titanium (Ti), Beryllium (Be), Magnesium (Mg), Nickel (Ni), Vanadium (V), Tin (Sn), Iron (Fe), Chromium (Cr), Zirconium (Zr), Strontium (Sr), 0.001 to 2.0 wt% of one or more elements selected from the group consisting of scandium (Sc) and manganese (Mn), 47 to 52 wt% of aluminum (Al), 2.0 to 3.0 wt% of copper (Cu), and silicon (Si) 0.001 High strength lightweight die casting zinc-aluminum alloy consisting of from 3.0 wt% and the balance zinc (Zn). Titanium (Ti), Beryllium (Be), Magnesium (Mg), Nickel (Ni), Vanadium (V), Tin (Sn), Iron (Fe), Chromium (Cr), Zirconium (Zr), Strontium (Sr), 0.001 to 1.0 wt% of one or more elements selected from the group consisting of scandium (Sc) and manganese (Mn), 47 to 52 wt% of aluminum (Al), 2.0 to 3.0 wt% of copper (Cu), and silicon (Si) 0.001 High strength lightweight die casting zinc-aluminum alloy consisting of from 3.0 wt% and the balance zinc (Zn).

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