CN103725947A - Ceramic particle enhanced magnesium-based composite material and preparation method thereof - Google Patents

Abstract

The preparation of magnesium-based composites by pressureless infiltration of ceramic prefabricated blocks by metal melt is a low-cost, fast, efficient, and near-net-forming preparation method. Due to the poor wettability between ceramics and metal systems, the infiltration process is very slow Difficult or even impossible to happen. Aiming at this problem, the present invention provides a ceramic particle-reinforced magnesium-based composite material and its preparation method, by adding a small amount of Ti, a third-phase component metal with a high melting point and immiscible with the magnesium melt, to the ceramic prefabricated block as the magnesium melt The impregnation inducer can effectively improve the wettability of the B ₄ C/Mg composite material system, and prepare the B ₄ C/Mg series ultra-light and high-abrasion-resistant ceramic particle-reinforced magnesium-based composite material. The method is to mechanically mix B ₄ C powder, Ti powder and binder and cold press them into ceramic prefabricated blocks, put the ceramic prefabricated blocks and pure magnesium ingots into an electric furnace for heating, and then melt the pure magnesium ingots and infiltrate them under the action of capillary force into the pores in the ceramic prefabricated block to prepare the ceramic particle reinforced magnesium matrix composite material.

Description

A kind of ceramic particle reinforced magnesium-based composite material and preparation method thereof

technical field

The invention belongs to the technical field of materials, and in particular relates to an ultra-light and highly wear-resistant magnesium-based composite material and a preparation method thereof.

Background technique

Materials are the foundation and forerunner of science and social progress, and a milestone of human progress. However, in the past 40 years, the rapid development of science and technology, especially the development of cutting-edge technologies such as aerospace and automobiles, has put forward more and more stringent requirements on the performance of materials, and traditional single materials can no longer meet these requirements. At this time, the emergence of composite materials has become an inevitable trend in the application and development of single materials such as metals and ceramics, and it is also a comprehensive sublimation of the properties of various single materials.

Metal matrix composites are composite materials that use metal or alloy as the matrix and ceramic fibers, whiskers, particles, etc. as reinforcements. It combines the toughness, electrical conductivity, thermal conductivity of metals and the high strength, high elastic modulus, wear resistance, high temperature resistance and corrosion resistance of ceramics. Compared with traditional metal materials, it has high specific strength. , specific stiffness, specific modulus, high temperature resistance, wear resistance, fatigue resistance, good damping, small thermal expansion coefficient, good chemical stability and dimensional stability, etc., have shown extremely wide applications in aerospace and automotive fields prospect. Magnesium-based composites are ceramic-reinforced magnesium-based composites based on pure magnesium or magnesium alloys. Because magnesium has the characteristics of low density, high specific strength and specific stiffness, magnesium-based composites are more popular than traditional metal materials in emerging technology fields. Aluminum matrix composites have greater application potential, and are known as green and sustainable new materials in the 21st century, showing great application prospects in the fields of aerospace, automobile manufacturing, electronic packaging, and sports equipment.

The preparation of magnesium-based composites by metal melt pressureless infiltration of ceramic prefabricated blocks is a low-cost, fast, efficient, and near-net-shaped composite preparation method. However, the premise of realizing this process is that there must be good wettability between ceramics and metals. In general, the wettability between ceramic and metal systems is not very good, which will lead to a significant reduction in the infiltration rate, or even the infiltration process cannot occur. Increasing the infiltration temperature is a method to solve the wettability of ceramic-metal melts; generally speaking, increasing the temperature has a certain effect on improving the wettability, but for low melting point metals like magnesium, the melt immersion Any small increase in infiltration temperature will intensify the rapid volatilization of magnesium metal melt, which not only increases the process cost, but also makes the preparation process impossible.

Contents of the invention

Aiming at the above-mentioned problems in the performance and process of existing magnesium-based composite materials, the present invention provides a ceramic particle-reinforced magnesium-based composite material and its preparation method, by adding a small amount of high-melting-point magnesium-based composite materials to ceramic prefabricated blocks that are incompatible with magnesium melts. The miscible third phase component metal Ti is used as the infiltration inducer of magnesium melt, which can effectively improve the wettability of the B ₄ C/Mg composite material system, and prepare the B ₄ C/Mg series ultra-light and high wear resistance ceramic particle reinforcement. Magnesium-based composites.

The technical solution adopted in the present invention is that a ceramic particle reinforced magnesium-based composite material is composed of a pure magnesium matrix and ceramic reinforced particles, wherein the volume of the pure magnesium matrix accounts for 40-50% of the total volume of the composite material, and the ceramic reinforced particles are composed of B ₄ Composed of C and Ti, the volume of Ti accounts for 6-8% of the total volume of ceramic reinforced particles; Ti and B ₄ C form a particle packing structure, and Mg infiltrates in the pores of the particle packing structure.

The density of the above-mentioned ceramic particle reinforced magnesium-based composite material is 2.09-2.22 g/cm ³ .

Another technical solution of the present invention is a preparation method of a ceramic particle reinforced magnesium-based composite material, the steps are as follows:

(1) Take B ₄ C powder with an average particle size of 5-28 μm, Ti powder and binder with an average particle size ≤ 25 μm, and mix them uniformly mechanically to obtain a mixed powder; the amount of Ti powder is the total amount of B ₄ C powder and Ti powder. 6-8% of the volume, the amount of binder is 5%-10% of the total volume of Ti powder and B ₄ C powder;

(2) The mixed powder is unidirectionally cold-pressed into a ceramic prefabricated block with a density of 50-60% by a press;

(3) Take a pure magnesium ingot with the same size as the ceramic prefabricated block, put the two into the graphite mold, the magnesium ingot is located above the ceramic prefabricated block, and the size of the contact surface between the two is the same;

(4) Put the graphite mold equipped with ceramic prefabricated blocks and pure magnesium ingots into the constant temperature zone of the vacuum resistance furnace. Under the condition of flowing argon gas atmosphere, raise the temperature to 275-285°C at 10K/min, and keep it warm for 10-15min. Let the binder volatilize and escape; then raise the temperature to 680-720°C at 10K/min, keep it warm for 90-150min, melt the pure magnesium ingot and infiltrate into the pores of the ceramic prefabricated block under the action of capillary force, and obtain Magnesium matrix composites reinforced with ceramic particles.

The above-mentioned binder is natural rubber.

其中，

为陶瓷预制块致密度，m_测为陶瓷预制块实际测量的质量，ρ_理为陶瓷预制块理论密度，φ为压制的预制块的直径，h为预制块的高度。The above-mentioned unidirectional cold pressing into a ceramic prefabricated block with a density of 50-60% refers to placing the ceramic mixed powder in a pressing mold, and using a press to unidirectionally compress it to a height corresponding to a density of 50-60%. value; relationship between density and block height:

in,

is the density of the ceramic prefabricated block, m _is the actual measured mass of the ceramic prefabricated block, ρ _is the theoretical density of the ceramic prefabricated block, φ is the diameter of the pressed prefabricated block, and h is the height of the prefabricated block.

The purity of the above-mentioned pure magnesium ingot is ≥99.95%.

The purity of the above-mentioned B ₄ C powder is ≥99.5%, and the purity of Ti powder is ≥99.5%.

The purity of the argon mentioned above is ≥99.999%.

The principle of method basis of the present invention is:

1. The impregnation of B ₄ C ceramic prefabricated blocks by pure magnesium melt is an extremely slow process. Spontaneous impregnation without the addition of the third phase component metal is impossible, or proceeds extremely slowly, and at temperatures below 750 °C, the spontaneous infiltration process cannot be realized. However, when a small amount of metal Ti is involved, that is, when immiscible high melting point metals are used to induce infiltration, at a temperature slightly higher than the melting point of metal magnesium, the speed of this process is greatly improved, and volatilization is also avoided; this is mainly The reason is that adding the third phase component high-melting point metal titanium (Ti) to the ceramic prefabricated block can reduce the surface tension and liquid/solid interfacial tension of the molten metal, thereby improving the wetting between the B ₄ C ceramic and the metal Mg melt. Wetness; even a small amount of titanium particles can induce the magnesium melt to achieve a rapid infiltration process, thereby producing ultra-light and highly wear-resistant particle-reinforced magnesium-based composites.

2. The density of B ₄ C ceramics is low, only 2.52g/cm ³ , and it is a material with high wear resistance and strong resistance to neutron radiation. The density of magnesium is also very low, 1.74g/cm ^3. Therefore, the density of particle reinforced magnesium matrix composites composed of B ₄ C and a small amount of Ti is still low, and it is still an ideal composite material with light weight and good wear resistance.

The features of the present invention are:

1. The present invention provides a ceramic-reinforced magnesium-based composite material. The composite material combines the advantages of magnesium and B ₄ C ceramics and has low density. At the same time, B ₄ C strengthens the magnesium matrix, and its wear resistance is also improved. It has been improved, its density is 2.09-2.22g/cm ³ , and its wear resistance is 22.2%-27.7% higher than that of pure magnesium. It can be used as a material for wear-resistant parts.

2. Considering the premise requirements of the metal melt infiltrating the ceramic prefabricated block, the optimal design was added to the ceramic prefabricated block to add the third phase Ti, a metal component with a high melting point and immiscible with the metal melt, to improve the wetting between the ceramic and the metal. Wetness, realizing the rapid impregnation of the metal melt into the ceramic prefabricated block.

3. Using the preparation method of the present invention, ceramic prefabricated blocks and pure magnesium ingots can be quickly infiltrated by metal melt into ceramic prefabricated blocks at a relatively low temperature (680-720°C), and the addition of adhesives is beneficial to enhance the strength of the prefabricated blocks. Strength, to facilitate the smooth progress of the impregnation process.

4. Using the preparation method of the present invention, ultra-light, wear-resistant ceramic particle reinforced magnesium-based composite materials can be obtained, which lays the foundation for the synthesis and application of low-cost hybrid reinforced magnesium-based composite materials, and also provides a basis for the use of high melting point metals to induce leaching It provides a reference for the preparation of intermetallic composites of other systems.

Description of drawings

Fig. 1 is the photomicrostructure picture of the ceramic particle reinforced magnesium-based composite material prepared in Example 1 of the present invention; the bright white particles in the figure are B ₄ C particles, the black part is the Mg matrix, and the Ti particle volume is very small, almost observed less than.

Fig. 2 is a photograph of the microstructure of the ceramic particle-reinforced magnesium-based composite material prepared in Example 1 of the present invention; the cross marks in the figure are Ti particles.

Fig. 3 is the curve diagram of the wear experiment of the ceramic particle reinforced magnesium-based composite material prepared in the embodiment of the present invention; each curve in the figure is the wear amount curve of metal magnesium, the ceramic particle reinforced magnesium-based composite material of embodiment 3 successively from top to bottom Wear curve, the wear curve of the ceramic particle reinforced magnesium matrix composite material of Example 2 and the wear curve of the ceramic particle reinforced magnesium matrix composite material of Example 1.

Detailed ways

The density measurement in the embodiment of the present invention adopts: METTLER TOLEDO XS105Dual Range analytical balance, the maximum weighing range is 41g/120g, and the readability is 0.01mg/0.1mg.

In the examples of the present invention, the observation of the microstructure of the ceramic particle-reinforced magnesium-based composite material is characterized by a FEI Quanta600 scanning electron microscope; its phase is determined by an X’Pert Pro X-ray diffractometer.

In the embodiment of the present invention, the wear resistance measurement adopts MG-2000 high-speed high-temperature friction and wear testing machine, the maximum positive pressure is 2000N, and the maximum rotating speed is 3200r/min; the test parameters are set as follows: the sliding speed is 250r/min, and the sliding time is 5min , the pressure is set to 20N, 40N, 60N, 80N in turn, and the plane perpendicular to the axial direction is used as the wear surface; the specific method is: before and after wear, the sample and the friction pair should be cleaned with ultrasonic alcohol for 20 minutes, and then the precision is 0.1 mg of electronic balance to weigh, to obtain the mass loss of the sample wear, wear amount as a measure of wear resistance standards.

The B ₄ C powder and Ti powder in the examples of the present invention are commercially available products; the weight purity of the B ₄ C powder is ≥99.5%, and the weight purity of the Ti powder is ≥99.5%.

The natural rubber in the examples of the present invention is a commercially available industrial product.

The magnesium ingots in the examples of the present invention are commercial products with a weight purity of ≥99.95%.

The argon in the examples of the present invention is a commercially available product with a volume purity ≥ 99.999%.

The graphite mold in the embodiment of the present invention is made of high-purity graphite with a weight purity of 99.9%.

其中，为陶瓷预制块致密度，m_测为陶瓷预制块实际测量的质量，ρ_理为陶瓷预制块理论密度，φ为压制的预制块的直径，h为预制块的高度。该公式是最终结果，推导公式没有一一列述。In the embodiment of the present invention, the unidirectional cold pressing into a ceramic prefabricated block with a density of 50-60% means that the ceramic mixed powder is placed in a _pressing mold, and it is unidirectionally compressed to a density of 50-60%. The height value corresponding to 60%; the relationship between the density and the height of the prefabricated block:

in, is the density of the ceramic prefabricated block, m _is the actual measured mass of the ceramic prefabricated block, ρ _is the theoretical density of the ceramic prefabricated block, φ is the diameter of the pressed prefabricated block, and h is the height of the prefabricated block. This formula is the final result, and the derivation formula is not listed one by one.

Example 1

A preparation method of ceramic particle reinforced magnesium-based composite material, the steps are as follows:

1. Take B ₄ C powder with an average particle size of 28 μm, Ti powder with an average particle size ≤ 25 μm, and binder liquid natural rubber, and mix them uniformly mechanically to obtain a mixed powder; wherein, the amount of Ti powder is the total amount of Ti powder and B ₄ C powder. 8% of the volume, the amount of binder is 5% of the total volume of Ti powder and B ₄ C powder;

2. Use a press to cold-press the mixed powder into a ceramic prefabricated block with a density of 60%;

3. Take a pure magnesium ingot with the same size as the ceramic prefabricated block, put the two into the graphite mold, the magnesium ingot is located above the ceramic prefabricated block, and the size of the contact surface between the two is the same;

4. Put the graphite mold equipped with ceramic prefabricated blocks and magnesium ingots into the constant temperature zone of the vacuum resistance furnace. Under the condition of flowing argon gas atmosphere, raise the temperature to 275°C at 10K/min and keep it warm for 10 minutes to make the binder high temperature. Volatilize, then raise the temperature to 720°C at a speed of 10K/min, and keep it warm for 150min, so that the pure magnesium ingot is melted and impregnated into the pores of the ceramic prefabricated block under the action of capillary force, and the ceramic particle reinforced magnesium matrix composite material is obtained.

The ceramic particle-reinforced magnesium-based composite material is composed of Mg matrix and ceramic reinforcing particles, the volume ratio of the two is 40%: 60%, the ceramic reinforcing particles are composed of B ₄ C and Ti, and the volume of Ti accounts for 8% of the total volume of the ceramic reinforcing particles , Ti and B ₄ C form a particle packing structure, and Mg infiltrates in the pores of the particle packing structure; the density of the composite material is 2.22g/cm ³ ;

MG-2000 high-speed high-temperature friction and wear testing machine was used to conduct wear experiments, and magnesium ingots were used as comparative experiments. The experimental results are shown in Figure 3; the microstructure photos are shown in Figures 1 and 2.

Example 2

A preparation method of ceramic particle reinforced magnesium-based composite material, the steps are as follows:

1. Take B ₄ C powder with an average particle size of 10 μm, Ti powder with an average particle size ≤ 25 μm, and binder liquid natural rubber, and mix them uniformly mechanically to obtain a mixed powder; wherein, the amount of Ti powder is the total amount of Ti powder and B ₄ C powder. 7% of the volume, the amount of binder is 8% of the total volume of Ti powder and B ₄ C powder;

2. Use a press to cold-press the mixed powder into a ceramic prefabricated block with a density of 55%;

3. Take a pure magnesium ingot with the same size as the ceramic prefabricated block, put the two into the graphite mold, the magnesium ingot is located above the ceramic prefabricated block, and the size of the contact surface between the two is the same;

4. Put the graphite mold equipped with ceramic prefabricated blocks and magnesium ingots into the constant temperature zone of the vacuum resistance furnace. Under the condition of flowing argon gas atmosphere, raise the temperature to 280°C at 10K/min and keep it warm for 12 minutes to make the binder high temperature. Volatilize, then raise the temperature to 700°C at a speed of 10K/min, and keep it warm for 120min, so that the pure magnesium ingot is melted and impregnated into the pores of the ceramic prefabricated block under the action of capillary force, and the ceramic particle reinforced magnesium matrix composite material is obtained.

The ceramic particle-reinforced magnesium-based composite material is composed of Mg matrix and ceramic reinforcing particles, the volume ratio of the two is 45%:55%, the ceramic reinforcing particles are composed of B ₄ C and Ti, and the volume of Ti accounts for 7% of the total volume of the ceramic reinforcing particles , Ti and B ₄ C form a particle packing structure, and Mg infiltrates in the pores of the particle packing structure; the density of the composite material is 2.15g/cm ³ .

MG-2000 high-speed high-temperature friction and wear testing machine was used to conduct wear experiments, and magnesium ingots were used as comparative experiments. The experimental results are shown in Figure 3.

Example 3

A preparation method of ceramic particle reinforced magnesium-based composite material, the steps are as follows:

1. Take B ₄ C powder with an average particle size of 5 μm, Ti powder with an average particle size ≤ 25 μm, and binder liquid natural rubber, and mix them uniformly mechanically to obtain a mixed powder; wherein, the amount of Ti powder is the total amount of Ti powder and B ₄ C powder. 6% of the volume, the amount of binder is 10% of the total volume of Ti powder and B ₄ C powder;

2. The mixed powder is unidirectionally cold-pressed into a ceramic prefabricated block with a density of 50% by a press;

3. Take a pure magnesium ingot with the same size as the ceramic prefabricated block, put the two into the graphite mold, the magnesium ingot is located above the ceramic prefabricated block, and the size of the contact surface between the two is the same;

4. Put the graphite mold equipped with ceramic prefabricated blocks and magnesium ingots into the constant temperature zone of the vacuum resistance furnace. Under the condition of flowing argon atmosphere, raise the temperature to 285°C at 10K/min and keep it warm for 15 minutes to make the binder high temperature. Volatilize, then raise the temperature to 680°C at a speed of 10K/min, and hold the temperature for 90 minutes, so that the pure magnesium ingot is melted and then impregnated into the pores of the ceramic prefabricated block under the action of capillary force, and the ceramic particle reinforced magnesium matrix composite material is obtained.

The ceramic particle-reinforced magnesium-based composite material is composed of Mg matrix and ceramic reinforcing particles, and the volume ratio of the two is 50%:50%. The ceramic reinforcing particles are composed of B ₄ C and Ti, and the volume of Ti accounts for 6% of the total volume of the ceramic reinforcing particles. , Ti and B ₄ C form a particle packing structure, and Mg infiltrates in the pores of the particle packing structure; the density of the composite material is 2.09g/cm ³ .

MG-2000 high-speed high-temperature friction and wear testing machine was used to conduct wear experiments, and magnesium ingots were used as comparative experiments. The experimental results are shown in Figure 3.

Claims (6)

1. A ceramic particle-reinforced magnesium-based composite material, consisting of pure magnesium matrix and ceramic reinforcement particles, is characterized in that the volume of the pure magnesium matrix accounts for 40 to 50% of the total volume of the composite material, and the ceramic reinforcement particles are composed of B ₄ C Composed of Ti and Ti, the volume of Ti accounts for 6-8% of the total volume of ceramic reinforced particles. 2 . The ceramic particle reinforced magnesium-based composite material according to claim 1 , characterized in that the density of the ceramic particle-reinforced magnesium-based composite material is 2.09˜2.22 g/cm ³ . 3. A method for preparing a ceramic particle reinforced magnesium-based composite material, characterized in that the steps are as follows: (1) Take B ₄ C powder with an average particle size of 5-28 μm, Ti powder and binder with an average particle size ≤ 25 μm, and mix them uniformly mechanically to obtain a mixed powder; the amount of Ti powder is the total amount of Ti powder and B ₄ C powder. 6-8% of the volume, the amount of binder is 5%-10% of the total volume of Ti powder and B ₄ C powder; (2) The mixed powder is unidirectionally cold-pressed into a ceramic prefabricated block with a density of 50-60% by a press; (3) Take a pure magnesium ingot with the same size as the ceramic prefabricated block, put the two into the graphite mold, the magnesium ingot is located above the ceramic prefabricated block, and the size of the contact surface between the two is the same; (4) Put the graphite mold equipped with ceramic prefabricated blocks and pure magnesium ingots into the constant temperature zone of the vacuum resistance furnace. Under the condition of flowing argon gas atmosphere, raise the temperature to 275-285°C at 10K/min, and keep it warm for 10-15min. Let the binder volatilize and escape; then raise the temperature to 680-720°C at 10K/min, keep it warm for 90-150min, melt the pure magnesium ingot and infiltrate into the pores of the ceramic prefabricated block under the action of capillary force, and obtain Magnesium matrix composites reinforced with ceramic particles. 4. The preparation method of a ceramic particle reinforced magnesium-based composite material according to claim 3, wherein the binder is natural rubber. 5. The preparation method of a ceramic particle reinforced magnesium-based composite material according to claim 3, characterized in that the purity of the argon gas is ≥99.999%. 6. A ceramic particle reinforced magnesium-based composite material according to claim 1 or a method for preparing a ceramic particle-reinforced magnesium-based composite material according to claim 3, wherein the purity of the pure magnesium ingot is ≥99.95%, the purity of B ₄ C powder is ≥99.5%, and the purity of Ti powder is ≥99.5%.

Images