CN110387490A - A kind of cast aluminum-silicon alloy with high thermal conductivity and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of high thermal conductivity cast Al-Si alloys and preparation method thereof, the high thermal conductivity cast Al-Si alloy is made of the element of following weight percent content: Si:3.3%-5.5%, Cu:0.1%-0.40%, Mg:0.26%-0.70%, Zn:0.04%-0.1%, Ti:0.05%-0.2%, B:0.05%-0.2%, other impurities total amount and be not more than 0.02%, surplus Al.Element of the present invention is effectively combined under conditions of specific alloy components containing composition and ratio by specific process step, can disposal molding be made thermal conductivity reach 172-190W/ (m k) cast Al-Si alloy, it realizes on the basis of good casting character, mechanical property and heat treatment performance, significantly improves the heating conduction of cast Al-Si alloy.High thermal conductivity cast Al-Si alloy prepared by the present invention has important application value, it can be widely applied to automobile, communication and field of electronic device, it can also be used in heat-transfer device, radiation shell etc., excellent heat transfer efficiency can promote the effective use of the energy, reduce energy consumption.

Description

A kind of cast aluminum-silicon alloy with high thermal conductivity and preparation method thereof

technical field

The invention belongs to the technical field of metal materials, and in particular relates to a cast aluminum-silicon alloy with high thermal conductivity and a preparation method thereof.

Background technique

The thermal conductivity of pure Al is second only to Au, Ag and Cu, which is 237W/(m·K). Al has the advantages of low price, low specific gravity, easy surface treatment, and high content in the earth's crust. Al-Si alloy is an important casting alloy. Due to its environmental protection, excellent casting performance, strong welding performance, good fluidity, good electrical and thermal conductivity, long life cycle and high recycling rate, etc., It is widely used in the field of heat dissipation components. With the development of the communication industry and electronic equipment, some electronic products, LED lighting equipment, and heat dissipation housings for communication base stations tend to be miniaturized and lightweight. With the increase of power density, the demand for heat dissipation performance is also increasing. Therefore, it is urgent to develop a material with high thermal conductivity to meet the high heat dissipation requirements of the equipment.

At present, the most commonly used aluminum-silicon alloys mainly include ZL101 and ZL102 series, whose thermal conductivity in the as-cast state is 121W/(m K), the tensile strength is about 130MPa, and the thermal conductivity after heat treatment is 148W/(m K). , The tensile strength is about 230MPa. There is also the commonly used die-casting aluminum alloy ADC12, the content of silicon is 12% at the eutectic point, and its thermal conductivity in the as-cast state is only 96W/(m·K), which is comparable to that of Al-Mg-Si deformed aluminum alloy. There must be a gap.

Therefore, improve the thermal conductivity of Al-Si cast aluminum alloys, expand the industrial application range of cast Al-Si alloys, and realize the metal mold casting process with lower processing costs to replace the extrusion profile machining process with higher processing costs, and obtain Good performance and low cost cast Al-Si alloys with high thermal conductivity are more and more required by people.

Contents of the invention

The object of the present invention is to solve the technical problems existing in the prior art, and provide a cast aluminum-silicon alloy with high thermal conductivity that has good casting performance and heat treatment performance and has relatively high thermal conductivity.

Another object of the present invention is to provide a method for preparing cast aluminum-silicon alloy with high thermal conductivity.

In order to achieve the above object, the present invention adopts the following technical solution: a cast aluminum-silicon alloy with high thermal conductivity, which is composed of the following elements by weight percentage: Si: 3.3%-5.5%, Cu: 0.1%-0.40%, Mg: 0.26 %-0.70%, Zn: 0.04%-0.1%, Ti: 0.05%-0.2%, B: 0.05%-0.2%, the total sum of other impurities is not more than 0.02%, and the balance is Al.

A method for preparing a cast aluminum-silicon alloy with high thermal conductivity, the method comprising the following steps:

1) Drying: Select pure aluminum ingots, Al-Si master alloys, Al-Cu master alloys, magnesium ingots, zinc ingots, and aluminum-titanium-boron refiners as raw materials according to the composition of the elements, and dry the raw materials;

2) Melting: first melt the pure aluminum ingot, when the temperature of the pure aluminum liquid reaches 850-900 ℃, then add the Al-Si master alloy, after the Al-Si master alloy is completely melted, then add the Al-Cu master alloy, After the Al-Cu intermediate alloy is completely melted, let it stand still for 15-20 minutes, then add magnesium ingots after standing still, add zinc ingots after the magnesium ingots are completely melted, and wait for the zinc ingots to be completely melted, stand still to obtain an alloy melt;

3) Alloying: When the temperature of the alloy melt drops to 720°C-750°C, add Al-Ti-B refiner to the alloy melt, stir well, and then remove slag with hexachloroethane, and wait until the temperature of the alloy melt reaches Pouring at 710°C-720°C to obtain cast aluminum-silicon alloy;

4) Heat treatment: The poured cast aluminum-silicon alloy is subjected to solution treatment, and the cast aluminum-silicon alloy after solid solution is quenched to obtain a cast aluminum-silicon alloy with high thermal conductivity.

Further, in the step 1), each raw material is dried at a temperature of 100°C.

Further, the purity of the pure aluminum ingots, magnesium ingots and zinc ingots in the step 1) is greater than 99.5%.

Further, the pit type crucible resistance furnace is used for melting in the step 2).

Further, the slag removal time in the step 3) is 5-10 minutes.

Further, during pouring in the step 3), it is poured into a metal mold with a preheating temperature of 200°C.

Further, the solid solution temperature in step 4) is 500-540° C., and the solid solution time is 8 hours.

Further, the solid solution sample in step 4) is quenched in warm water at 33-37°C, and the quenching time is less than 10s.

Compared with the prior art, the present invention has the following beneficial effects:

1. In the composition of the high thermal conductivity cast aluminum-silicon alloy of the present invention, silicon as an alloying element can improve the casting performance and mechanical properties of the alloy, but with the increase of the silicon element content, the excess silicon element is solid-dissolved in the aluminum matrix on the one hand, On the other hand, the formation of coarse β phase with aluminum will reduce the thermal conductivity of aluminum alloy and cause a decrease in thermal conductivity. After systematic research and comparison of alloy components, it is found that silicon should be controlled in the range of 3.3%-5.5%. Inside. As alloying elements, copper and magnesium can be combined with silicon to achieve aging strengthening, forming Al ₂ Cu and Mg ₂ Si strengthening phases respectively, but as the content of copper and magnesium increases, the amount dissolved into the aluminum matrix increases, causing lattice distortion As the degree increases, the thermal conductivity decreases. Therefore, in order to achieve the best combination of mechanical properties and thermal conductivity, the content of copper and magnesium should be limited to Cu: 0.10%-0.40%, Mg: 0.26% through systematic research and comparison of alloy components -0.70% range. The addition of zinc can improve the fluidity and castability of aluminum alloy, increase the strength and corrosion resistance of the alloy, and form η (MgZn ₂ ) and T (Al ₂ Mg ₂ Zn ₃ ) phases, η and T phases when zinc and magnesium coexist The high solubility in Al will cause serious lattice distortion of the aluminum matrix, destroy the regularity of the ionic electric field, increase the resistance of moving electrons, increase the mean free path of electrons, and eventually lead to a decrease in thermal conductivity. On the basis of ensuring the fluidity of the alloy, the zinc content should be limited within the range of Zn: 0.04%-0.1% through systematic research and comparison of the alloy composition. The above-mentioned elements are effectively combined through specific process steps under the condition of specific alloy composition ratios, and cast aluminum-silicon alloys with a thermal conductivity of 172-190W/(m∙k) can be produced at one time, achieving good casting performance, On the basis of mechanical properties and heat treatment properties, the thermal conductivity of cast aluminum-silicon alloys is significantly improved. The cast aluminum-silicon alloy with high thermal conductivity prepared by the invention has important application value, and can be widely used in the fields of automobiles, communications and electronic equipment, and can also be used in heat conduction devices, heat dissipation shells, etc., and its excellent heat transfer efficiency can promote the effective use of energy. use to reduce energy consumption.

2. The present invention selects raw materials according to the element composition during the preparation of cast aluminum-silicon alloys with high thermal conductivity, and then obtains the final cast aluminum-silicon alloy with high thermal conductivity after drying, smelting, alloying, and heat treatment. There is a strict logic between each step relationship, and each step sets specific process parameters. After comparison, the traditional casting method is used to prepare the alloy, and the obtained alloy has casting defects, but the special heat treatment method after smelting and alloying of the present invention can eliminate dendrite segregation in the as-cast structure, and improve the regularity of the ion electric field Sex, reduce the mean free path in the process of electron movement, to improve thermal conductivity. The present invention creatively obtains the optimal solution temperature, solution time, quenching temperature and quenching time under better thermal conductivity and mechanical properties through extensive research on the influence trend of solid solution temperature on alloy thermal conductivity.

Detailed ways

The present invention will be further described below in conjunction with specific examples.

Example 1

A cast aluminum-silicon alloy with high thermal conductivity, composed of the following elements by weight percentage: Si: 3.3%, Cu: 0.10%, Mg: 0.26%, Zn: 0.08%, Ti: 0.05%, B: 0.2%, others The total sum of impurities is not more than 0.02%, and the balance is Al.

The preparation method of the cast aluminum-silicon alloy with high thermal conductivity comprises the following steps:

1) Drying: Select pure aluminum ingots with a purity greater than 99.5%, Al-Si master alloys, Al-Cu master alloys, magnesium ingots with a purity greater than 99.5%, zinc ingots with a purity greater than 99.5%, and Al-Ti-B fines according to the composition of the elements. Chemical agent is used as raw material, and the raw material is dried at 100°C;

2) Melting: first use the well-type crucible resistance furnace to melt the pure aluminum ingot, when the temperature of the pure aluminum liquid reaches 900 ℃, then add the Al-Si master alloy, after the Al-Si master alloy is completely melted, then add the Al- Cu intermediate alloy, after the Al-Cu intermediate alloy is completely melted, let it stand still for 15-20min, then add magnesium ingot after standing still, add zinc ingot after the magnesium ingot is completely melted, after the zinc ingot is completely melted, stand still to obtain alloy melt body;

3) Alloying: When the alloy melt cools down to 750°C, add an aluminum-titanium-boron refiner to the alloy melt. The amount of the aluminum-titanium-boron refiner added is 0.3% of the total weight of the alloy melt, and it is fully stirred. Then use hexachloroethane to remove slag, and the time for removing slag is 5 minutes. When the alloy melt temperature reaches 720°C, pour it into a metal mold with a preheating temperature of 200°C to obtain a cast aluminum-silicon alloy;

4) Heat treatment: The poured cast aluminum-silicon alloy is subjected to solution treatment, the solution temperature is 500°C, and the solution time is 8 hours. After solid solution, the cast aluminum-silicon alloy is quenched in warm water at 33°C. The time is less than 10s.

Example 2

A cast aluminum-silicon alloy with high thermal conductivity, composed of the following elements by weight percentage: Si: 3.9%, Cu: 0.3%, Mg: 0.38%, Zn: 0.04%, Ti: 0.12%, B: 0.12%, others The total sum of impurities is not more than 0.02%, and the balance is Al.

The preparation method of the cast aluminum-silicon alloy with high thermal conductivity comprises the following steps:

1) Drying: Select pure aluminum ingots with a purity greater than 99.5%, Al-Si master alloys, Al-Cu master alloys, magnesium ingots with a purity greater than 99.5%, zinc ingots with a purity greater than 99.5%, and Al-Ti-B fines according to the composition of the elements. Chemical agent is used as raw material, and the raw material is dried at 100°C;

2) Melting: first use the well-type crucible resistance furnace to melt the pure aluminum ingot, when the temperature of the pure aluminum liquid reaches 850 ℃, then add the Al-Si master alloy, after the Al-Si master alloy is completely melted, then add the Al- Cu intermediate alloy, after the Al-Cu intermediate alloy is completely melted, let it stand still for 15-20min, then add magnesium ingot after standing still, add zinc ingot after the magnesium ingot is completely melted, after the zinc ingot is completely melted, stand still to obtain alloy melt body;

3) Alloying: When the alloy melt cools down to 735°C, add aluminum-titanium-boron refiner to the alloy melt, the amount of aluminum-titanium-boron refiner added is 0.3% of the total weight of the alloy melt, fully stir, Then use hexachloroethane to remove the slag, and the slag removal time is 8 minutes. When the temperature of the alloy melt reaches 715°C, it is poured into a metal mold with a preheating temperature of 200°C to obtain a cast aluminum-silicon alloy;

4) Heat treatment: The poured cast aluminum-silicon alloy is subjected to solution treatment, the solution temperature is 520°C, and the solution time is 8 hours. After solid solution, the cast aluminum-silicon alloy is quenched in warm water at 35°C. The time is less than 10s.

Example 3

A cast aluminum-silicon alloy with high thermal conductivity, composed of the following elements by weight percentage: Si: 5.5%, Cu: 0.4%, Mg: 0.70%, Zn: 0.1%, Ti: 0.2%, B: 0.05%, others The total sum of impurities is not more than 0.02%, and the balance is Al.

The preparation method of the cast aluminum-silicon alloy with high thermal conductivity comprises the following steps:

1) Drying: Select pure aluminum ingots with a purity greater than 99.5%, Al-Si master alloys, Al-Cu master alloys, magnesium ingots with a purity greater than 99.5%, zinc ingots with a purity greater than 99.5%, and Al-Ti-B fines according to the composition of the elements. Chemical agent is used as raw material, and the raw material is dried at 100°C;

2) Melting: first use the well-type crucible resistance furnace to melt the pure aluminum ingot, when the temperature of the pure aluminum liquid reaches 880 ℃, then add the Al-Si master alloy, after the Al-Si master alloy is completely melted, then add the Al- Cu intermediate alloy, after the Al-Cu intermediate alloy is completely melted, let it stand still for 15-20min, then add magnesium ingot after standing still, add zinc ingot after the magnesium ingot is completely melted, after the zinc ingot is completely melted, stand still to obtain alloy melt body;

3) Alloying: When the alloy melt cools down to 720°C, add aluminum-titanium-boron refiner to the alloy melt, the amount of aluminum-titanium-boron refiner added is 0.3% of the total weight of the alloy melt, fully stir, Then use hexachloroethane to remove slag, and the slag removal time is 10 minutes. When the temperature of the alloy melt reaches 710°C, it is poured into a metal mold with a preheating temperature of 200°C to obtain a cast aluminum-silicon alloy;

4) Heat treatment: The poured cast aluminum-silicon alloy is subjected to solution treatment, the solution temperature is 540°C, and the solution time is 8 hours. After solid solution, the cast aluminum-silicon alloy is quenched in warm water at 37°C. The time is less than 10s.

Comparative test 1

The preparation method of Comparative Example 1 is the same as that of Example 1, but no solution treatment is performed to obtain a cast aluminum-silicon alloy A ₀ .

Comparative experiment 2: Effect of alloying element Si on thermal conductivity and mechanical properties of cast aluminum-silicon alloy

The preparation methods in Comparative Test 2 are the same as those in Examples 1, 2, and 3 (the poured aluminum-silicon alloys were solid solution treated at 500°C, 520°C, and 540°C respectively, and the solid solution time was 8 hours. The cast aluminum-silicon alloy is quenched in warm water at 33°C, 35°C, and 37°C, and the quenching time is less than 10s), but the content of alloy elements is different, and it is composed of the following elements by weight percentage: Si: 2.5%, 3.3 %, 5.5%, 6%, Cu: 0.10%, Mg: 0.26%, Zn: 0.08%, Ti: 0.05%, B: 0.2%, the total sum of other impurities is not more than 0.02%, and the balance is Al.

Comparative experiment 3: Effect of alloying element Cu on thermal conductivity and mechanical properties of cast aluminum-silicon alloy

The preparation method in Comparative Test 3 is the same as that of Examples 1, 2, and 3 (the poured aluminum-silicon alloys were solid solution treated at 500°C, 520°C, and 540°C respectively, and the solid solution time was 8 hours. The cast aluminum-silicon alloy is quenched in warm water at 33°C, 35°C, and 37°C, and the quenching time is less than 10s), but the content of alloy elements is different, and it is composed of the following elements by weight percentage: Si: 3.3%, Cu : 0%, 0.1%, 0.4%, 0.5%, 0.6%, Mg: 0.26%, Zn: 0.08%, Ti: 0.05%, B: 0.2%, the total sum of other impurities is not more than 0.02%, and the balance is Al .

Comparative Test 4: Effect of Alloying Element Mg on Thermal Conductivity and Mechanical Properties of Cast Al-Si Alloy

The preparation methods in Comparative Test 4 are the same as those in Examples 1, 2, and 3 (the poured aluminum-silicon alloys were solid solution treated at 500°C, 520°C, and 540°C respectively, and the solid solution time was 8 hours. The cast aluminum-silicon alloy is quenched in warm water at 33°C, 35°C, and 37°C, and the quenching time is less than 10s), but the content of alloy elements is different, and it is composed of the following elements by weight percentage: Si: 3.3%, Cu: 0.10%, Mg: 0.1%, 0.26%, 0.7%, 0.8%, Zn: 0.08%, Ti: 0.05%, B: 0.2%, the total sum of other impurities is not more than 0.02%, and the balance is Al.

Comparative experiment 5: Effect of alloying element Zn on thermal conductivity and mechanical properties of cast aluminum-silicon alloy

The preparation methods in Comparative Test 5 are the same as those in Examples 1, 2, and 3, (the poured aluminum-silicon alloys were solid solution treated at 500°C, 520°C, and 540°C respectively, and the solid solution time was 8 hours. The melted cast aluminum-silicon alloy is quenched in warm water at 33°C, 35°C, and 37°C, and the quenching time is less than 10s), but the content of alloy elements is different, and it is composed of the following elements by weight percentage: Si: 3.3%, Cu: 0.10%, Mg: 0.26%, Zn: 0.02%, 0.04%, 0.1%, 0.2%, Ti: 0.05%, B: 0.2%, the total sum of other impurities is not more than 0.02%, and the balance is Al.

The specific alloy content of Comparative Test 2-5 is shown in Table 1.

Table 1 Contrastive Test 2-5 specific alloy content (wt%)

The casting aluminum-silicon alloy that makes in the embodiment and comparative example is done further performance detection below:

Mechanical properties and thermal conductivity:

The cast aluminum-silicon alloys prepared in the above examples 1-3 and the cast aluminum-silicon alloys prepared in comparative tests 1-5 were prepared according to the GB requirements and tested for room temperature tensile test (tensile strength, elongation) and thermal conductivity. Test (Φ12.7mm×5mm), the test results are shown in Table 2-6.

Table 2 Example 1-3 and comparative test 1 cast aluminum-silicon alloy performance table

Table 3 Performance table of cast aluminum-silicon alloy in comparative test 2

Table 4 Performance table of cast aluminum-silicon alloy in comparative test 3

Table 5 Performance table of cast aluminum-silicon alloy in comparative test 4

Table 6 Performance table of cast aluminum-silicon alloy in comparative test 5

According to the data in the above table 2, it can be seen that the thermal conductivity of the cast aluminum-silicon alloy with high thermal conductivity of the present invention can reach more than 172W/(m∙k), the highest can reach 190W/(m∙k), and the tensile strength can reach Above 234.39 MPa, up to 255.74MPa. In comparison example 1, the thermal conductivity of the Al-Si alloy in the as-cast state is only 153W/(m∙k), and the tensile strength is 188.35MPa. From comparative examples 2-5, it can be seen that when the alloy elements exceed a certain range, the best combination of thermal conductivity and mechanical properties cannot be achieved, only Si: 3.3%-5.5%, Cu: 0.1%-0.40%, Mg: 0.26%-0.70%, Zn: 0.04%-0.1%, the thermal conductivity and mechanical properties can achieve the best match. It can be seen that, when the alloying elements in the cast aluminum-silicon alloy are within a specific range, the thermal conductivity of the present invention is significantly improved after heat treatment; in addition, the present invention also ensures a relative High mechanical properties greatly expand the scope of industrial applications.

Claims (9)

1. A cast aluminum-silicon alloy with high thermal conductivity, characterized in that: it consists of the following elements by weight percentage: Si: 3.3%-5.5%, Cu: 0.1%-0.40%, Mg: 0.26%-0.70%, Zn : 0.04%-0.1%, Ti: 0.05%-0.2%, B: 0.05%-0.2%, the total sum of other impurities is not more than 0.02%, and the balance is Al. 2. A method for preparing the high thermal conductivity cast aluminum-silicon alloy according to claim 1, characterized in that: the method comprises the following steps: 1) Drying: Select pure aluminum ingots, Al-Si master alloys, Al-Cu master alloys, magnesium ingots, zinc ingots, and aluminum-titanium-boron refiners as raw materials according to the composition of the elements, and dry the raw materials; 2) Melting: first melt the pure aluminum ingot, when the temperature of the pure aluminum liquid reaches 850-900 ℃, then add the Al-Si master alloy, after the Al-Si master alloy is completely melted, then add the Al-Cu master alloy, After the Al-Cu intermediate alloy is completely melted, let it stand still for 15-20 minutes, then add magnesium ingots after standing still, add zinc ingots after the magnesium ingots are completely melted, and wait for the zinc ingots to be completely melted, stand still to obtain an alloy melt; 3) Alloying: When the temperature of the alloy melt drops to 720°C-750°C, add Al-Ti-B refiner to the alloy melt, stir well, and then remove slag with hexachloroethane, and wait until the temperature of the alloy melt reaches Pouring at 710°C-720°C to obtain cast aluminum-silicon alloy; 4) Heat treatment: The poured cast aluminum-silicon alloy is subjected to solution treatment, and the cast aluminum-silicon alloy after solid solution is quenched to obtain a cast aluminum-silicon alloy with high thermal conductivity. 3. The method for preparing a cast aluminum-silicon alloy with high thermal conductivity according to claim 2, characterized in that: in the step 1), each raw material is dried at a temperature of 100°C. 4 . The method for preparing a cast aluminum-silicon alloy with high thermal conductivity according to claim 2 , wherein the purity of pure aluminum ingots, magnesium ingots and zinc ingots in the step 1) is greater than 99.5%. 5 . The method for preparing a cast aluminum-silicon alloy with high thermal conductivity according to claim 2 , characterized in that: a well-type crucible resistance furnace is used for melting in the step 2). 6 . The method for preparing a cast aluminum-silicon alloy with high thermal conductivity according to claim 2 , wherein the slag removal time in the step 3) is 5-10 minutes. 7 . The method for preparing a cast aluminum-silicon alloy with high thermal conductivity according to claim 2 , characterized in that: when pouring in the step 3), it is poured into a metal mold with a preheating temperature of 200° C. 7 . 8 . The method for preparing a cast aluminum-silicon alloy with high thermal conductivity according to claim 2 , wherein the solution temperature in step 4) is 500-540° C., and the solution time is 8 hours. 9. The method for preparing a cast aluminum-silicon alloy with high thermal conductivity according to claim 2, characterized in that: the solid solution sample in step 4) is quenched in warm water at 33-37°C, Quenching time is less than 10s.