Aluminum alloy for automobile piston and preparation method thereof

Abstract

The present invention provides an aluminum alloy for automobile pistons and a preparation method thereof, the preparation method being as follows: using aluminum ingots and crystalline silicon as raw materials to make a binary master alloy; adding magnesium ingots, Al-Cu alloy ingots and Al-Mn alloy ingots to perform a multi-element alloying process; refining the alloy material after melting and standing; adding enhanced-modified particles to stir and keep warm; refining for a second time, while starting a pulse device to apply a pulse current to the alloy melt to keep warm; cooling to 800°C and pouring into a mold; after the sample solidifies and cools, heat treatment is performed using a T6 heat treatment process. The present invention uses enhanced-modified particles to simultaneously possess mechanical enhancement and modification effects. Simply using nano-titanium boride will result in uneven distribution in the aluminum alloy, and nano-scale particles are prone to agglomeration, thereby affecting its effect. Particles prepared by electrostatic spinning can prevent the agglomeration of particles while loading the P element. In addition, enhanced-modified particles can also improve the plasticity of the aluminum alloy, an effect that cannot be achieved by simple nanoparticles.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy materials, and in particular to an aluminum alloy for automobile pistons and a preparation method thereof. Background Art

[0002] The world's earliest automobile engine pistons were made of cast iron. Research on using aluminum alloys to manufacture pistons only began in 1911. In 1920, an aluminum-copper-nickel-magnesium alloy was officially and successfully applied to automobile engine pistons. In the following decades, several series of aluminum alloy materials for pistons were successfully researched.

[0003] As automobile engine speeds continue to increase, piston speeds also increase. Gasoline engine piston speeds can reach 11-16 m / s; diesel engine piston speeds can reach 6-8.5 m / s, or even higher. As a result of engine speed increases, the inertial force acting on the piston increases, and the engine's compression ratio also increases. This dramatically increases the combustion velocity within the combustion chamber, easily creating localized pressure differentials within the cylinder, causing forced piston vibration and leading to cavitation or knocking. Furthermore, the piston head is susceptible to thermal deformation or cracking due to alternating thermal stresses. Therefore, in addition to certain requirements for piston material properties such as room-temperature strength, hardness, elongation, and thermal expansion coefficient, high-temperature properties, such as high-temperature tensile strength, high-temperature fatigue strength, thermal conductivity, and wear resistance, are also highly demanding.

[0004] To meet the requirements of high-speed automobile engines, after extensive research, piston materials have become increasingly sophisticated, and their various properties have been greatly improved. As piston materials, commonly used aluminum alloys can be roughly divided into the following four categories: (1) aluminum-copper-silicon alloys; (2) aluminum-copper-nickel-magnesium alloys; (3) aluminum-silicon-nickel-magnesium alloys; and (4) high-silicon aluminum alloys. Among them, the greatest advantages of high-silicon aluminum alloys are low thermal expansion coefficient, good wear resistance, and low density. This is incomparable to the first three types of alloys. The disadvantages are relatively low tensile strength and poor processing performance. Therefore, corresponding improvements must be made. Summary of the Invention

[0005] Technical problem to be solved: In response to the above technical problems, the purpose of the present invention is to provide an aluminum alloy for automobile pistons and a preparation method thereof, which adopts reinforcement-modification particles and has both mechanical reinforcement effect and modification effect. The simple use of nano-titanium boride will result in uneven distribution in the aluminum alloy, and nano-scale particles are prone to agglomeration, thereby affecting its effect. The particles prepared by electrospinning can prevent the agglomeration of particles and load the P element at the same time. In addition, the reinforcement-modification particles can also improve the plasticity of the aluminum alloy, which is an effect that simple nanoparticles cannot achieve.

[0006] Technical solution: A method for preparing aluminum alloy for automobile pistons, comprising the following steps:

[0007] S1: Using aluminum ingot and crystalline silicon as raw materials, an Al-26% Si binary master alloy is prepared;

[0008] S2: adding magnesium ingot, Al-Cu alloy ingot and Al-Mn alloy ingot, performing multi-element alloying treatment, and obtaining an alloy material containing 21.5%-23% Si, 1.5%-2.5% Cu, 0.6%-1.2% Mg, and 0.5%-0.7% Mn;

[0009] S3: After melting the alloy material, refine it with C2Cl6 at 840℃ and let it stand for 5-10 minutes;

[0010] S4: Add the enhanced-modified particles and stir and keep warm for 60 min;

[0011] S5: Add C2Cl6 for the second refining, and start the pulse equipment to apply pulse current to the alloy melt, and keep it warm for 5 minutes; S6: Cool it down to 800℃ and pour it into the mold, and the mold preheating temperature is 200℃;

[0012] S7: After the sample solidifies and cools, it can be heat treated using the T6 heat treatment process.

[0013] Furthermore, the aluminum ingot is a 99% aluminum ingot; the magnesium ingot is a 99% magnesium ingot; the Al-Cu alloy ingot is an Al-50% Cu master alloy ingot; and the Al-Mn alloy ingot is an Al-10% Mn master alloy ingot.

[0014] Furthermore, the preparation method of the enhanced-modified particles is as follows:

[0015] S41: dissolving polyethylene glycol in a mixed solvent to prepare a solution with a concentration of 20 wt %;

[0016] S42: adding glucose and nano-titanium boride and stirring evenly to prepare the electrospinning solution;

[0017] S43: performing electrospinning using an electrospinning device to obtain an electrospinning membrane;

[0018] S44: drying the electrospun membrane and then sintering it at a temperature of 1050-1350° C.;

[0019] S45: After being taken out and crushed, the particles are immersed in a phosphoric acid solution with a concentration of 10-16%, and then taken out and dried to obtain enhanced-modified particles.

[0020] Furthermore, the mixed solvent is n-butanol, N-methylpyrrolidone and anhydrous ethanol in a mass ratio of 7:3:2.

[0021] Furthermore, the mass ratio of the polyethylene glycol, glucose and nano-titanium boride is 10:0.5:(4-7).

[0022] Furthermore, the electrospinning conditions are as follows: spinning voltage is 18 kV, the distance from the needle to the receiving plate is 15 cm, and the spinning solution flow rate is 2.0 mL / h.

[0023] Furthermore, the particle size of the enhanced-modified particles is ≤0.05 μm.

[0024] Furthermore, the pulse electrodes of the pulse device are made of high-precision graphite electrodes.

[0025] Furthermore, the pulse frequency and pulse voltage of the pulse current are 30-35 Hz and 25-28 V, respectively.

[0026] Furthermore, the mass ratio of the reinforcement-modification particles to the alloy material is (2-15):100.

[0027] The aluminum alloy for automobile piston is prepared by the above method.

[0028] Beneficial effects:

[0029] 1. The present invention uses reinforcing-modifying particles, which have both mechanical strengthening and modification effects. The simple use of nano-titanium boride will result in uneven distribution in the aluminum alloy, and the nano-scale particles are prone to agglomeration, thus affecting its effect. The particles prepared by electrospinning can prevent the agglomeration of particles and load the P element at the same time. In addition, the reinforcing-modifying particles can also improve the plasticity of the aluminum alloy, which is an effect that cannot be achieved by simple nanoparticles.

[0030] 2. In the present invention, the surface of the enhanced-modified particles is loaded with P element, and P forms AlP with Al. AlP particles will not aggregate into clusters. AlP particles can be maintained for a long time as heterogeneous cores. The loading on the surface of the enhanced-modified particles makes their structure more stable, further increasing the durability of the modification effect and preventing the modification effect from fading.

[0031] 3. The strengthening-modifying particles of the present invention are composed of carbon-nano boron nitride. During the reaction process, the nano boron nitride is dispersed in the melt to form a large amount of TiAl3 in the master alloy, which promotes grain refinement. At the same time, the three-dimensional network structure of the strengthening-modifying particles can better composite with the alloy. DETAILED DESCRIPTION

[0032] The present invention provides an aluminum alloy for automotive pistons and a method for preparing the same. To clarify the objectives, technical solutions, and effects of the present invention, the present invention will be further described below with reference to the following examples. It should be understood that the specific examples described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0033] Example 1

[0034] The preparation method of the enhanced-modified particles is as follows:

[0035] S41: dissolving polyethylene glycol in a mixed solvent to prepare a solution with a concentration of 20 wt %; the mixed solvent is n-butanol, N-methylpyrrolidone, and anhydrous ethanol in a mass ratio of 7:3:2;

[0036] S42: Glucose and nano-titanium boride are added and stirred evenly to prepare the electrospinning solution; the mass ratio of polyethylene glycol, glucose and nano-titanium boride is 10:0.5:4;

[0037] S43: electrospinning is performed using an electrospinning device to obtain an electrospun membrane; the electrospinning conditions are: spinning voltage of 18 kV, distance from the needle to the receiving plate of 15 cm, and spinning solution flow rate of 2.0 mL / h;

[0038] S44: drying the electrospun membrane and then sintering it at a temperature of 1200° C.;

[0039] S45: After being taken out and crushed, the particles are immersed in a phosphoric acid solution with a concentration of 14%, and then taken out and dried to obtain enhanced-modified particles.

[0040] The particle size of the enhanced-modified particles is ≤0.05μm.

[0041] Example 2

[0042] The preparation method of the enhanced-modified particles is as follows:

[0043] S41: dissolving polyethylene glycol in a mixed solvent to prepare a solution with a concentration of 20 wt %; the mixed solvent is n-butanol, N-methylpyrrolidone, and anhydrous ethanol in a mass ratio of 7:3:2;

[0044] S42: Glucose and nano-titanium boride are added and stirred evenly to prepare the electrospinning solution; the mass ratio of polyethylene glycol, glucose and nano-titanium boride is 10:0.5:6;

[0045] S43: electrospinning is performed using an electrospinning device to obtain an electrospun membrane; the electrospinning conditions are: spinning voltage of 18 kV, distance from the needle to the receiving plate of 15 cm, and spinning solution flow rate of 2.0 mL / h;

[0046] S44: drying the electrospun membrane and then sintering it at a temperature of 1200° C.;

[0047] S45: After being taken out and crushed, the particles are immersed in a phosphoric acid solution with a concentration of 14%, and then taken out and dried to obtain enhanced-modified particles.

[0048] The particle size of the enhanced-modified particles is ≤0.05μm.

[0049] Example 3

[0050] The preparation method of the enhanced-modified particles is as follows:

[0051] S41: dissolving polyethylene glycol in a mixed solvent to prepare a solution with a concentration of 20 wt %; the mixed solvent is n-butanol, N-methylpyrrolidone, and anhydrous ethanol in a mass ratio of 7:3:2;

[0052] S42: Glucose and nano-titanium boride are added and stirred evenly to prepare the electrospinning solution; the mass ratio of polyethylene glycol, glucose and nano-titanium boride is 10:0.5:7;

[0053] S43: electrospinning is performed using an electrospinning device to obtain an electrospun membrane; the electrospinning conditions are: spinning voltage of 18 kV, distance from the needle to the receiving plate of 15 cm, and spinning solution flow rate of 2.0 mL / h;

[0054] S44: drying the electrospun membrane and then sintering it at a temperature of 1200° C.;

[0055] S45: After being taken out and crushed, the particles are immersed in a phosphoric acid solution with a concentration of 14%, and then taken out and dried to obtain enhanced-modified particles.

[0056] The particle size of the enhanced-modified particles is ≤0.05μm.

[0057] Example 4

[0058] The preparation method of the enhanced-modified particles is as follows:

[0059] S41: dissolving polyethylene glycol in a mixed solvent to prepare a solution with a concentration of 20 wt %; the mixed solvent is n-butanol, N-methylpyrrolidone, and anhydrous ethanol in a mass ratio of 7:3:2;

[0060] S42: Glucose and nano-titanium boride are added and stirred evenly to prepare the electrospinning solution; the mass ratio of polyethylene glycol, glucose and nano-titanium boride is 10:0.5:6;

[0061] S43: electrospinning is performed using an electrospinning device to obtain an electrospun membrane; the electrospinning conditions are: spinning voltage of 18 kV, distance from the needle to the receiving plate of 15 cm, and spinning solution flow rate of 2.0 mL / h;

[0062] S44: drying the electrospun membrane and then sintering it at a temperature of 1200° C.;

[0063] S45: After being taken out and crushed, the particles are immersed in a phosphoric acid solution with a concentration of 10%, and then taken out and dried to obtain enhanced-modified particles.

[0064] The particle size of the enhanced-modified particles is ≤0.05μm.

[0065] Example 5

[0066] The preparation method of the enhanced-modified particles is as follows:

[0067] S41: dissolving polyethylene glycol in a mixed solvent to prepare a solution with a concentration of 20 wt %; the mixed solvent is n-butanol, N-methylpyrrolidone, and anhydrous ethanol in a mass ratio of 7:3:2;

[0068] S42: Glucose and nano-titanium boride are added and stirred evenly to prepare the electrospinning solution; the mass ratio of polyethylene glycol, glucose and nano-titanium boride is 10:0.5:6;

[0069] S43: electrospinning is performed using an electrospinning device to obtain an electrospun membrane; the electrospinning conditions are: spinning voltage of 18 kV, distance from the needle to the receiving plate of 15 cm, and spinning solution flow rate of 2.0 mL / h;

[0070] S44: drying the electrospun membrane and then sintering it at a temperature of 1200° C.;

[0071] S45: After being taken out and crushed, the particles are immersed in a phosphoric acid solution with a concentration of 16%, and then taken out and dried to obtain enhanced-modified particles.

[0072] The particle size of the enhanced-modified particles is ≤0.05μm.

[0073] Example 6

[0074] The aluminum ingot is a 99% aluminum ingot, the magnesium ingot is a 99% magnesium ingot, the Al-Cu alloy ingot is an Al-50% Cu master alloy ingot, and the Al-Mn alloy ingot is an Al-10% Mn master alloy ingot. (These are the same as in the embodiment)

[0075] Different mass ratios of reinforcement-modification particles and alloy materials are used:

[0076] A method for preparing an aluminum alloy for an automobile piston comprises the following steps:

[0077] S1: Using aluminum ingot and crystalline silicon as raw materials, an Al-26% Si binary master alloy is prepared;

[0078] S2: adding magnesium ingot, Al-Cu alloy ingot and Al-Mn alloy ingot, performing multi-element alloying treatment, and obtaining an alloy material containing 22% Si, 2.0% Cu, 1.0% Mg, and 0.6% Mn;

[0079] S3: After melting the alloy material, it is refined with C2Cl6 at 840℃ and allowed to stand for 8 minutes;

[0080] S4: adding the reinforcement-modification particles prepared in Example 4, with the mass ratios of the reinforcement-modification particles to the alloy material being 2:100, 5:100, 10:100 and 15:100 respectively, and stirring and keeping warm for 60 min;

[0081] S5: Add C2Cl6 for the second refining, and start the pulse equipment to apply pulse current to the alloy melt. The pulse electrode uses a high-precision graphite electrode, the pulse frequency and pulse voltage are 33Hz and 27V respectively, and the temperature is kept for 5 minutes;

[0082] S6: Cool down to 800℃ and pour into the mold. The mold preheating temperature is 200℃;

[0083] S7: After the sample solidifies and cools, it can be heat treated using the T6 heat treatment process.

[0084] Aluminum alloys for automobile pistons according to Example 6-1, Example 6-2, Example 6-3 and Example 6-4 were obtained respectively and subsequently subjected to performance tests.

[0085] Example 7

[0086] Different pulse voltages were used, Example 7-1 (pulse frequency 30 Hz, pulse voltage 25 V), Example 7-2 (pulse frequency 35 Hz, pulse voltage 28 V):

[0087] A method for preparing an aluminum alloy for an automobile piston comprises the following steps:

[0088] S1: Using aluminum ingot and crystalline silicon as raw materials, an Al-26% Si binary master alloy is prepared;

[0089] S2: adding magnesium ingot, Al-Cu alloy ingot and Al-Mn alloy ingot, performing multi-element alloying treatment, and obtaining an alloy material containing 22% Si, 2.0% Cu, 1.0% Mg, and 0.6% Mn;

[0090] S3: After melting the alloy material, it is refined with C2Cl6 at 840℃ and allowed to stand for 8 minutes;

[0091] S4: adding the reinforced-modified particles prepared in Example 4, with the mass ratio of reinforced-modified particles to alloy material being 10:100, stirring and keeping warm for 60 minutes;

[0092] S5: Add C2Cl6 for the second refining, and start the pulse equipment to apply pulse current to the alloy melt. The pulse electrode uses a high-precision graphite electrode, the pulse frequency and pulse voltage are 30-35Hz and 25-28V respectively, and the heat is kept for 5 minutes;

[0093] S6: Cool down to 800℃ and pour into the mold. The mold preheating temperature is 200℃;

[0094] S7: After the sample solidifies and cools, it can be heat treated using the T6 heat treatment process.

[0095] The aluminum alloys for automobile pistons of Example 7-1 and Example 7-2 were obtained respectively, and subsequent performance tests were performed.

[0096] Example 8

[0097] Reinforced-modified particles prepared in different embodiments:

[0098] A method for preparing an aluminum alloy for an automobile piston comprises the following steps:

[0099] S1: Using aluminum ingot and crystalline silicon as raw materials, an Al-26% Si binary master alloy is prepared;

[0100] S2: adding magnesium ingot, Al-Cu alloy ingot and Al-Mn alloy ingot, performing multi-element alloying treatment, and obtaining an alloy material containing 22% Si, 2.0% Cu, 1.0% Mg, and 0.6% Mn;

[0101] S3: After melting the alloy material, it is refined with C2Cl6 at 840℃ and allowed to stand for 8 minutes;

[0102] S4: adding the reinforced-modified particles prepared in Example 1, Example 2, Example 3 and Example 5 respectively, with the mass ratio of reinforced-modified particles to alloy material being 10:100, stirring and keeping warm for 60 minutes;

[0103] S5: Add C2Cl6 for the second refining, and start the pulse equipment to apply pulse current to the alloy melt. The pulse electrode uses a high-precision graphite electrode, the pulse frequency and pulse voltage are 30-35Hz and 25-28V respectively, and the heat is kept for 5 minutes;

[0104] S6: Cool down to 800℃ and pour into the mold. The mold preheating temperature is 200℃;

[0105] S7: After the sample solidifies and cools, it can be heat treated using the T6 heat treatment process.

[0106] Aluminum alloys for automobile pistons according to Example 8-1, Example 8-2, Example 8-3 and Example 8-4 were obtained respectively and subjected to subsequent performance tests.

[0107] Comparative Example 1

[0108] The difference between this embodiment and embodiment 6-3 is that pulse assistance is not used. Specifically:

[0109] A method for preparing an aluminum alloy for an automobile piston comprises the following steps:

[0110] S1: Using aluminum ingot and crystalline silicon as raw materials, an Al-26% Si binary master alloy is prepared;

[0111] S2: adding magnesium ingot, Al-Cu alloy ingot and Al-Mn alloy ingot, performing multi-element alloying treatment, and obtaining an alloy material containing 22% Si, 2.0% Cu, 1.0% Mg, and 0.6% Mn;

[0112] S3: After melting the alloy material, it is refined with C2Cl6 at 840℃ and allowed to stand for 8 minutes;

[0113] S4: adding the reinforced-modified particles prepared in Example 4, with the mass ratio of reinforced-modified particles to alloy material being 10:100, stirring and keeping warm for 60 minutes;

[0114] S5: Add C2Cl6 for the second refining and keep warm for 5 minutes;

[0115] S6: Cool down to 800℃ and pour into the mold. The mold preheating temperature is 200℃;

[0116] S7: After the sample solidifies and cools, it can be heat treated using the T6 heat treatment process.

[0117] Comparative Example 2

[0118] The difference between this embodiment and embodiment 6-3 is that instead of using reinforcing-modifying particles, an equal amount of nano-titanium boride immersed in phosphoric acid is directly added. Specifically:

[0119] The preparation method of nano titanium boride immersed in phosphoric acid is as follows: nano titanium boride is immersed in a phosphoric acid solution with a concentration of 14%, and then taken out and dried.

[0120] A method for preparing an aluminum alloy for an automobile piston comprises the following steps:

[0121] S1: Using aluminum ingot and crystalline silicon as raw materials, an Al-26% Si binary master alloy is prepared;

[0122] S2: adding magnesium ingot, Al-Cu alloy ingot and Al-Mn alloy ingot, performing multi-element alloying treatment, and obtaining an alloy material containing 22% Si, 2.0% Cu, 1.0% Mg, and 0.6% Mn;

[0123] S3: After melting the alloy material, it is refined with C2Cl6 at 840℃ and allowed to stand for 8 minutes;

[0124] S4: adding nano-titanium boride immersed in phosphoric acid, the mass ratio of nano-titanium boride immersed in phosphoric acid to the alloy material is 10:100, stirring and keeping warm for 60 minutes;

[0125] S5: Add C2Cl6 for the second refining, and start the pulse equipment to apply pulse current to the alloy melt. The pulse electrode uses a high-precision graphite electrode, the pulse frequency and pulse voltage are 33Hz and 27V respectively, and the temperature is kept for 5 minutes;

[0126] S6: Cool down to 800℃ and pour into the mold. The mold preheating temperature is 200℃;

[0127] S7: After the sample solidifies and cools, it can be heat treated using the T6 heat treatment process.

[0128] The mechanical strength of each embodiment was tested using a universal testing machine, and the results are as follows:

[0129] Table 1 Mechanical properties of each embodiment

[0130]

Claims

1. A method for preparing an aluminum alloy for automobile pistons, characterized in that: The following steps are involved: S1: Using aluminum ingot and crystalline silicon as raw materials, an Al-26%Si binary master alloy is prepared; S2: adding magnesium ingot, Al-Cu alloy ingot and Al-Mn alloy ingot, performing multi-element alloying treatment, and obtaining an alloy material containing 21.5%-23% Si, 1.5%-2.5% Cu, 0.6%-1.2% Mg, and 0.5%-0.7% Mn; S3: After melting the alloy material, refine it with C2Cl6 at 840℃ and let it stand for 5-10 minutes; S4: Add the enhanced-modified particles and stir and keep warm for 60 min; S5: Add C2Cl6 for the second refining, and start the pulse equipment to apply pulse current to the alloy melt, and keep it warm for 5 minutes; S6: Cool down to 800℃ and pour into the mold. The mold preheating temperature is 200℃; S7: After the sample solidifies and cools, it can be heat treated using the T6 heat treatment process; The preparation method of the enhanced-modified particles is as follows: S41: dissolving polyethylene glycol in a mixed solvent to prepare a solution with a concentration of 20 wt%; S42: adding glucose and nano-titanium boride and stirring evenly to prepare the electrospinning solution; S43: performing electrospinning using an electrospinning device to obtain an electrospinning membrane; S44: drying the electrospun membrane and then sintering it at a temperature of 1050-1350° C.; S45: After being taken out and crushed, the particles are immersed in a phosphoric acid solution having a concentration of 10-16%, and then taken out and dried to obtain enhanced-modified particles; The mixed solvent is n-butanol, N-methylpyrrolidone and anhydrous ethanol in a mass ratio of 7:3:2; The mass ratio of the polyethylene glycol, glucose and nano-titanium boride is 10:0.5:(4-7); The particle size of the enhanced-modified particles is ≤0.05 μm; The mass ratio of the reinforcement-modification particles to the alloy material is (2-15):

100.

2. The method for preparing an aluminum alloy for automobile piston according to claim 1, characterized in that: The aluminum ingot is a 99% aluminum ingot; the magnesium ingot is a 99% magnesium ingot; the Al-Cu alloy ingot is an Al-50%Cu intermediate alloy ingot; and the Al-Mn alloy ingot is an Al-10%Mn intermediate alloy ingot.

3. The method for preparing an aluminum alloy for automobile piston according to claim 1, characterized in that: The electrospinning conditions are as follows: spinning voltage of 18 kV, distance from needle to receiving plate of 15 cm, and spinning solution flow rate of 2.0 mL / h.

4. The method for preparing an aluminum alloy for automobile piston according to claim 1, characterized in that: The pulse frequency and pulse voltage of the pulse current are 30-35 Hz and 25-28 V, respectively.

5. Aluminum alloy for automobile piston prepared by the method according to any one of claims 1 to 4.

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