CN108060369A - The preparation method of silicon carbide ceramic fiber/particle reinforced metal-base composites - Google Patents

Abstract

This divisional application is related to the preparation method of silicon carbide ceramic fiber/particle reinforced metal-base composites, and addition Al particles dissolve each other with molten state Al based alloys, have many advantages, such as low cost compared with traditional solid phase method, liquid phase method, efficient.It is effectively controlled the generation of the interfacial reaction between SiC/Al.In friction, the interface product of film-form is spread composite material in which can organize crackle, enhances the combination power between strengthening material and matrix, improves the wear-resisting property of material.For silicon carbide ceramic fiber prepared by the present invention/particle reinforced metal-base composites compared with existing metal-base composites, the wear-resisting property of material is more excellent, is with a wide range of applications.

Description

Preparation method of silicon carbide ceramic fiber/particle reinforced metal matrix composite

This application is a divisional application with the application number 2017103685184, the application date is May 22, 2017, and the title of the invention is "Preparation of SiC Ceramic Fiber/Particle Reinforced Al-based Alloy Composite Materials by Low-Pressure Pressing Method".

technical field

The invention relates to the fabrication of SiC ceramic fiber/particle reinforced metal matrix composite materials, especially reinforced Al-based alloy composite materials, under low pressure.

Background technique

In recent years, metal matrix composites (Metal Material Composite: MMC) have been widely used in locomotives, aviation and other fields because of their high specific strength, specific modulus, and wear resistance. With the advent of metal matrix composites, various manufacturing processes such as high-pressure pressurized casting and powder metallurgy have been developed. However, both of these methods have drawbacks.

Silicon carbide (SiC) has stable chemical properties, high thermal conductivity, small thermal expansion coefficient, and good wear resistance. In addition to being used as an abrasive, it has many other uses. Because of its high strength and high modulus, it is used by locomotives, aviation field is recognized. SiC particle reinforced metal alloy composite materials have been applied on the brake disc of Toyota Motor in Japan. However, in the current research, the interface reaction between Al-based alloy and SiC will occur at high temperature, and in general, the interface reaction will have a negative effect on the mechanical properties of the material. The more types of interface reactions, the more negative effects on the mechanical properties. The larger it is, the original intention of adding rigid particles to improve the mechanical properties of metal alloys will be violated.

Contents of the invention

In order to solve the deficiencies of the prior art, the present invention prepares SiC ceramic fiber/particle reinforced Al-based alloy composite material by low pressure infiltration (Low pressure infiltration: LPI), the casting time is short, and by suppressing the interface reaction between SiC/Al, Form a thin film on the surface of the alloy, prevent the spread of cracks, improve the bonding force between the reinforced material and the base material, and improve the mechanical properties and wear resistance of the composite material.

In order to achieve the above object, the present invention adopts the following technical solutions.

The preparation method of SiC ceramic fiber/particle reinforced Al-based alloy composite is as follows:

(1) Add binder to the beaker filled with ethanol, after the binder is completely dissolved, add pure Al particles, SiC particles and SiC fibers, so that the liquid and SiC fibers/particles are evenly attached;

(2) Put the sample obtained in step (1) into the test tube, compress both ends of the test tube at the same time to make a cylinder with a height of 1 to 2 cm, place the cylinder in a 773K electric furnace and heat it to completely decompose the adhesive and take it out , to obtain a SiC ceramic body;

(3) Arrange the ceramic beads, SiC ceramic body and Al-based alloy from bottom to top in an experimental tube with an opening diameter of 0.5-0.8 mm, and heat it with a high-frequency heater until the Al-based alloy is completely melted, from Add Ar gas 0.2-0.4MPa above the test tube to the surface of the liquid alloy, so that the liquid alloy penetrates into the SiC ceramic body; when the liquid alloy slowly flows out from the tip of the test tube, stop pressurizing and cool to obtain an Al-based alloy composite material.

Preferably, the pure Al particle has a diameter of 18 μm, the SiC particle has a diameter of 20-50 μm, and the SiC fiber is a fiber with a cut length of 0.5 mm and a diameter of 20 μm. In this size range, the distribution of particles is more uniform, the gap between particles is not large, and the wear resistance of the sample is the best.

Preferably, the step (2) specifically includes: putting the sample obtained in the step (1) into a test tube with a diameter of 15 mm, and simultaneously compressing both ends into a cylinder with a height of 1 cm. Heat in an electric furnace at a temperature of 773K for 1 hour to completely decompose the PEG and take it out to obtain a SiC ceramic body.

Preferably, step (3) specifically includes: placing ceramic beads with a diameter of 1mm, SiC ceramic embryos and Al-based alloys in sequence from bottom to top in an experimental tube with an opening diameter of 0.5-0.8mm, and passing the high-frequency Heat the heater to 1173K to completely melt the Al-based alloy, add 0.2MPaAr gas from the top of the test tube to the surface of the liquid alloy for 15s, stop pressurizing, and cool to obtain an Al-based alloy composite material.

Preferably, the Al-based alloy is a copper-aluminum alloy with a Cu content of 4 mass%, a magnesium-aluminum alloy with a Mg content of 4 mass%, or a silicon-aluminum alloy with a Si content of 12 mass%.

Preferably, the binder is polyethylene glycol (PEG).

If the opening diameter is too large, the liquid alloy will flow out instantly when pressurized, and if it is too small, the pressure value requirements will be increased and the state of low pressure pressurization cannot be achieved. The addition of ceramic beads can effectively prevent the liquid from being sprayed out directly after being pressurized. Preferably, the diameter of the ceramic beads is 1mm.

The present invention can be completed under very low pressure (0.2MPa) by the low-pressure pressurization method, and the casting time is generally 15 seconds. Due to the short time and fast speed, the generation of interface reaction is effectively suppressed, and a Films with a layer thickness of less than 1 μm. On the one hand, the film can protect the surface of strengthening materials such as silicon carbide from damage, on the other hand, the film can effectively prevent silicon carbide from falling off during friction and prevent the spread of cracks. The bonding force between silicon carbide and the base material is improved so that the wear resistance of the composite material is improved. Compared with the traditional solid-phase method and liquid-phase method, the present invention has the advantages of simple preparation process, low cost and high efficiency.

Description of drawings

Fig. 1 is the comparison result of the friction and wear test of the metal matrix composite material of the present invention;

Figure 2 is a scanning electron microscope photo of the interface structure of the SiC/Al-Si metal matrix composite after friction;

Figure 3a is a scanning electron microscope photo of the SiC/Al-Cu interface structure after friction;

Figure 3b is a transmission electron microscope photo of the SiC/Al-Cu interface structure after friction;

Figure 4a is a scanning electron microscope photo of the SiC/Al-Mg rubbed structure;

Figure 4b is a transmission electron microscope photo of the SiC/Al-Mg rubbed structure.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with specific examples, but the present invention is not limited by the content of the examples in any form. The experimental methods described in the examples are conventional methods unless otherwise specified, and the chemical reagents and materials can be obtained from commercial sources unless otherwise specified.

The present invention relates to SiC/Al-Cu, which means that the composite material is a composite material prepared with Al-4mass% Cu (Cu content is 4mass%) as the base material, SiC particles and SiC fibers;

SiC/Al-Si represents a composite material prepared with Al-12mass% Si (Si content is 12mass%) as the substrate, SiC particles and SiC fibers;

SiC/Al-Mg represents a composite material prepared with Al-4mass%Mg (Mg content is 4mass%) as the substrate, SiC particles and SiC fibers;

Example 1

Add 2g of binder PEG to a beaker containing 20ml of ethanol, and after it is completely dissolved, add 0.8g of pure Al particles (diameter: 18μm) with a volume fraction of 7.5vol.% SiC particles (diameter of 50μm), with a volume fraction of 12.5vol .% SiC fibers (diameter: 20 μm, shear length 0.5 mm), put into a beaker and stir to make the liquid mixture adhere to SiC particles and SiC fibers. Put the mixed sample into a test tube with a diameter of 15mm, compress both ends of the test tube at the same time, compress it into a cylinder with a height of 1cm, and heat it in a 773K electric furnace for 1 hour to completely decompose the PEG and take it out to obtain SiC Ceramic bodies.

Using Al-4mass%Cu as the base material, ceramic beads with a diameter of 1mm, SiC ceramic blanks and Al-4mass%Cu alloy are arranged in sequence from bottom to top in an experimental tube with an opening diameter of 0.5-0.8mm. The role of the ceramic beads is to prevent the liquid metal from flowing instantly after being pressurized. In this embodiment, aluminum oxide beads with a diameter of 1mm are used. The experimental tube was heated to 1173K by a high-frequency heater to completely melt the alloy. Add 0.2MPaAr gas from the top of the test tube to the surface of the liquid alloy, so that the alloy penetrates into the SiC ceramic body. When the liquid alloy contacts the Al particles, the Al particles melt immediately, and the pressurization time is 15s. Stop pressurizing when the liquid alloy slowly flows out from the tip of the test tube. After cooling, the MMC sample was obtained.

Example 2

Add 2g of binder PEG to a beaker containing 20ml of ethanol, and after it is completely dissolved, add 0.8g of pure Al particles (diameter: 18μm) with a volume fraction of 7.5vol.% SiC particles (diameter of 50μm), with a volume fraction of 12.5vol .% SiC fibers (diameter: 20 μm, shear length 0.5 mm), put into a beaker and stir to make the liquid mixture adhere to SiC particles and SiC fibers. Put the mixed sample into a test tube with a diameter of 15mm, compress both ends of the test tube at the same time, compress it into a cylinder with a height of 1cm, and heat it in a 773K electric furnace for 1 hour to completely decompose the PEG and take it out to obtain SiC Ceramic bodies.

Using Al-4mass%Mg as the base material, ceramic beads with a diameter of 1mm, SiC ceramic blanks and Al-4mass%Mg alloy are arranged in sequence from bottom to top in an experimental tube with an opening diameter of 0.5-0.8mm. The role of the ceramic beads is to prevent the liquid metal from flowing instantly after being pressurized. In this embodiment, aluminum oxide beads with a diameter of 1mm are used. The experimental tube was heated to 1173K by a high-frequency heater to completely melt the alloy. Add 0.2MPaAr gas from the top of the test tube to the surface of the liquid alloy, so that the alloy penetrates into the SiC ceramic body. When the liquid alloy contacts the Al particles, the Al particles melt immediately, and the pressurization time is 15s. Stop pressurizing when the liquid alloy slowly flows out from the tip of the test tube. After cooling, the MMC sample was obtained.

Example 3

Add 2g of binder PEG to a beaker containing 20ml of ethanol, and after it is completely dissolved, add 0.8g of pure Al particles (diameter: 18μm) with a volume fraction of 7.5vol.% SiC particles (diameter of 50μm), with a volume fraction of 12.5vol .% SiC fibers (diameter: 20 μm, shear length 0.5 mm), put into a beaker and stir to make the liquid mixture adhere to SiC particles and SiC fibers. Put the mixed sample into a test tube with a diameter of 15mm, compress both ends of the test tube at the same time, compress it into a cylinder with a height of 1cm, and heat it in a 773K electric furnace for 1 hour to completely decompose the PEG and take it out to obtain SiC Ceramic bodies.

Using Al-12mass% Si as the base material, ceramic beads with a diameter of 1 mm, SiC ceramic green body and Al-12mass% Si alloy are arranged in sequence from bottom to top in an experimental tube with an opening diameter of 0.5-0.8 mm. The role of the ceramic beads is to prevent the liquid metal from flowing instantly after being pressurized. In this embodiment, aluminum oxide beads with a diameter of 1mm are used. The experimental tube was heated to 1173K by a high-frequency heater to completely melt the alloy. Add 0.2MPaAr gas from the top of the test tube to the surface of the liquid alloy, so that the alloy penetrates into the SiC ceramic body. When the liquid alloy contacts the Al particles, the Al particles melt immediately, and the pressurization time is 15s. Stop pressurizing when the liquid alloy slowly flows out from the tip of the test tube. After cooling, the MMC sample was obtained.

The composite material prepared in embodiment 1, implementation 2 and embodiment 3 is carried out performance test, adopts national Vickers hardness standard hardness tester according to GB/T4340, the test Al-4mass%Cu that carries out under 1kg load, Al-4mass The Vickers hardness of %Mg, Al-12mass% Si alloys are 42, 54, 68 in turn. When the content of Si in Example 3 is 12%, it is a eutectic point, which has higher mechanical properties. For the above three materials, the wear resistance of the three composite materials was tested by friction and wear experiments, and the wear resistance results are shown in Figure 1. The horizontal axis is the friction distance, and the vertical axis is the mass loss. As the friction distance increases, the wear is smaller and the wear resistance is better. The metal matrix composite material made of SiC/Al-Cu has the smallest wear loss, and its wear resistance Sex is the best. The wear resistance of SiC/Al-Mg composites is better than SiC/Al-Si, but worse than SiC/Al-Cu, because the interfacial reaction between SiC/Al-Mg improves the strength between the strengthening material and the matrix. binding force, while there are two interface reactants in SiC/Al-Mg. Due to the increase in the species of reactants, it has a negative effect on the combination between the interfaces. The hardness of the Al-4mass% Cu-based alloy composite in Example 1 is the lowest, but the wear resistance of the Al-4mass%Cu-based alloy composite is the best.

The interface reaction between SiC and Al groups in the composite materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 was observed by scanning electron microscope and transmission electron microscope. The results are shown in Figures 2-4. It can be seen from Figure 2 that the SiC/Al-Si alloy is smooth and no interface reaction occurs. It can be seen from Figure 3a that there is an interface reaction between the SiC/Al-Cu alloy. It is confirmed from Figure 3b that the interface reactant is Al. ₄ C ₃ , it can be seen that the reaction of formula (1) occurs on the interface:

3SiC(S)+4Al(L)→Al ₄ C ₃ (S)+3Si(L) (1)

It can be seen from Figure 4a that there is an interface reaction between the SiC/Al-Mg alloys, and it is confirmed from Figure 4b that the interface reactants include Al ₄ C ₃ and Mg ₂ Si, that is, the interface reaction between the alloys in Comparative Example 1 Formula (2) reaction

4Al(L)+3SiC(S)+6Mg(L)→Al ₄ C ₃ (S)+Mg ₂ Si(S) (2)

To sum up, SiC/Al-Cu forms interface substance Al ₄ C ₃ , SiC/Al-Mg forms interface substance Al ₄ C ₃ and Mg ₂ Si, and there is no interface reaction between SiC/Al-Si.

Claims (4)

1. The preparation method of silicon carbide ceramic fiber/particle reinforced metal matrix composite material, is characterized in that, comprises the following steps: (1) preparing SiC ceramic body; (2) Place the ceramic beads, SiC ceramic body and Al-based alloy in sequence from bottom to top, heat through a high-frequency heater until the Al-based alloy is completely melted, and add 0.2-0.4 MPa of Ar gas to the surface of the liquid alloy, The liquid alloy is infiltrated into the SiC ceramic body; when the liquid alloy slowly flows out from the mouth of the test tube, the pressurization is stopped, and the metal matrix composite material is obtained after cooling. 2. The preparation method according to claim 1, characterized in that the diameter of the ceramic beads in the step (2) is 1mm. 3. The preparation method according to claim 1, characterized in that, the heater heating temperature in step (2) is 1173K. 4. The preparation method according to claim 1, characterized in that, in the step (2), the pressure of the heater is 0.2Mpa.