CN109400210B

CN109400210B - Ti3SiC2-Al2O3-SiC-Al composite material and preparation method thereof

Info

Publication number: CN109400210B
Application number: CN201811451802.9A
Authority: CN
Inventors: 曹晓明; 于亚军; 马瑞娜; 杜安; 范永哲; 赵雪
Original assignee: Hebei University of Technology
Current assignee: Hebei University of Technology
Priority date: 2018-11-30
Filing date: 2018-11-30
Publication date: 2021-07-06
Anticipated expiration: 2038-11-30
Also published as: CN109400210A

Abstract

The invention is a Ti₃SiC₂‑Al₂O₃-SiC-Al composite material and a preparation method thereof. The outer layer of the composite material is Ti₃SiC₂/Al₂O₃The interior of the/SiC reaction layer is made of a SiC/Al composite material; the thickness of the reaction layer is 100-400 μm. In the outer layer of the composite material, the volume percentage of Ti₃SiC₂：60～80％，Al₂O₃: 15% -40%, SiC: 5 to 20 percent. The method firstly obtains Ti by a reaction infiltration method₃SiC₂The composite material is subjected to a one-step in-situ oxidation treatment process, and the outer surface Ti is oxidized by controlling oxidation process parameters (oxidation temperature and oxidation time)₃SiC₂Al generated by Al in-situ oxidation in the gap with SiC₂O₃To change the surface layer into Ti₃SiC₂/Al₂O₃and/SiC. The composite material prepared by the invention has high toughness and good frictional wear performance.

Description

Ti3SiC2-Al2O3-SiC-Al composite material and preparation method thereof

Technical Field

The invention belongs to the technical field of ceramic matrix composite materials, and particularly relates to Ti₃SiC₂-Al₂O₃-SiC-Al composite material and a preparation method thereof.

Background

The SiC ceramic is widely applied to efficient high-speed cutting tools, space technology and engine because of the characteristics of light weight, high strength, good heat conductivity, low expansion coefficient, high hardness, excellent thermal property and mechanical property and the likeKey parts, sealing parts, new energy development and other novel industries. However, like other ceramic materials, SiC ceramic materials have inherently higher coefficients of friction and wear rates, are brittle materials, have low fracture toughness, and have a much lower critical load for fracture of the ceramic surface than under static conditions during sliding friction. In addition, during the rubbing process, the rubbing surface generates continuous transition gap local stress concentration, and then microcracks are generated. The application of the SiC ceramic is limited because the blocking of grain boundaries in the SiC ceramic forces microcracks not to further expand and only can be aggregated to cause brittle fracture of micro-regions. Al (Al)₂O₃As a structural ceramic, the ceramic has a series of advantages of high hardness, light weight, excellent wear resistance and the like. Ti₃SiC₂The ternary layered ceramic has the advantages of high melting point, high chemical stability, corrosion resistance, heat conduction, electric conduction, easy processing, self lubrication and the like of the ceramic. Especially Ti₃SiC₂The self-lubricating performance can play a good antifriction effect and reduce the friction coefficient.

With self-lubricating material Ti₃SiC₂And wear-resistant material Al₂O₃Attention to Al₂O₃/Ti₃SiC₂Composite material and pure Ti₃SiC₂The preparation of powder and block is more studied, and Ti is₃SiC₂/SiC and Al₂O₃/Ti₃SiC₂The two composites,/SiC, have been relatively less studied. To date, Ti₃SiC₂The preparation method of the/SiC composite material mainly focuses on two methods of powder hot-pressing sintering and liquid silicon infiltration of a Ti-C-Si system. Yi Hong Feng et al (Yi Hong Feng, Fan Qiang, ren Shen, etc.. SiC content vs. Ti₃SiC₂Effect of the Properties of the/SiC composite [ J]. Journal of aeronautical materials, 2008, 6(28)78-81.) adopts TiH₂TiC and C powder are sintered by hot pressing to prepare Ti₃SiC₂The performance of the/SiC composite material is not greatly improved because the powder sintering cannot easily obtain a dense ceramic composite material. Qinghua university Qingfeng et Al ( Qingfeng, Wang Chang an, Huangyong, Li Cui Wei, Zhao Shi Ke, Al)₂O₃/Ti₃SiC₂Preparation and Properties of layered composite Material [ J]. Material engineering, 2003, 09, 15-21.) two methods were used to prepare Al₂O₃/Ti₃SiC₂Layered composite materials, one being in situ hot pressing at 1600 deg.C, i.e. Ti₃SiC₂Are synthesized simultaneously during the preparation of the layered material; one is a step-by-step method, i.e. the preparation process is carried out in two steps, firstly Ti is prepared₃SiC₂High-purity powder, and sintering by adopting a hot pressing method to prepare the layered material. Al prepared by two methods₂O₃/Ti₃SiC₂The microstructure of the layered composite material has obvious difference, which also causes the difference in mechanical property, the material prepared by the in-situ hot pressing method has higher strength and lower breaking work, and the material prepared by the step method has lower strength and higher breaking work. Moreover, high temperature and high pressure conditions are required, and the preparation conditions are severe, so that the significance of the two methods is not great.

Chinese patent with application number 201310314549.3 discloses Ti₃Si(Al)C₂The preparation method of the modified SiC-based composite material comprises the steps of pretreating SiC prefabricated bodies in multiple steps, carrying out vacuum infiltration and pressure infiltration on the prefabricated bodies, paving Al-Si alloy on the surfaces of the prefabricated bodies, and calcining at high temperature in a vacuum environment to prepare Ti₃Si(Al)C₂The modified SiC-based composite material reduces the damage and residual thermal stress to SiC fibers, and the strength of the prepared composite material is obviously improved. But the preparation conditions of the process are harsh, the process needs to be completed under vacuum and high temperature, and the cost is high, so that the process is not suitable for large-scale industrial production.

Chinese patent with application number of 201711365973.5' A Ti₃SiC₂Preparation method of/SiC/Al composite material ", and Ti is prepared₃SiC₂The Al alloy infiltrates into the SiC matrix, and the surface of the composite material is polished to obtain Ti on the surface of the sample₃SiC₂A certain amount of aluminum still exists in the clearance of SiC, Al belongs to a soft phase, the hardness is low, the antifriction and wear-resisting properties are poor, and the lubricating phase Ti is not included₃SiC₂Is generated but is made ofThe overall hardness of the surface layer is low, the average Vickers hardness is about 580Hv, the surface wear resistance of the composite material is extremely poor, and the wear resistance of the composite material is seriously influenced.

Disclosure of Invention

The invention aims to provide Ti aiming at the defects of the prior art₃SiC₂-Al₂O₃A preparation method of-SiC-Al self-lubricating composite material. The method firstly obtains Ti by an infiltration method₃SiC₂The composite material is subjected to a one-step in-situ oxidation treatment process, and the outer surface Ti is oxidized by controlling oxidation process parameters (oxidation temperature and oxidation time)₃SiC₂Al generated by Al in-situ oxidation in the gap with SiC₂O₃To change the surface layer into Ti₃SiC₂/Al₂O₃and/SiC. The composite material prepared by the invention has high toughness and good frictional wear performance.

The technical scheme adopted by the invention for solving the technical problem is as follows:

ti₃SiC₂-Al₂O₃-SiC-Al composite material, the outer layer of the composite material is Ti₃SiC₂/Al₂O₃The interior of the/SiC reaction layer is made of a SiC/Al composite material; the thickness of the reaction layer is 100-400 μm.

In the outer layer of the composite material, the volume percentage of Ti₃SiC₂：60～80％，Al₂O₃：15％～40％，SiC：5％～20％

The Ti₃SiC₂-Al₂O₃A method for preparing an-SiC-Al composite material, the method comprising the steps of:

(1) preparing the aluminum-based alloy: the aluminum alloy comprises the following elements in percentage by mass: al, 45-90 wt.%; ti, 3-25 wt.%; mg,1-6 wt.%; si, 5-30 wt.%;

weighing corresponding raw materials according to the mass percent of the elements, immersing a pure aluminum ingot in NaOH solution for 1-3 hours, completely removing surface oxide skin, placing the pure aluminum ingot in a graphite crucible, placing the pure aluminum ingot, magnesium powder and silicon block in the graphite crucible, heating to 700-1100 ℃ for melting, and preserving heat for 0.5-4 hours under stirring to obtain molten aluminum-based alloy solution;

(2) pretreatment of SiC ceramic: cutting the SiC ceramic into required corresponding sizes, polishing, ultrasonically cleaning and drying;

(3) and (3) a reaction infiltration process: immersing the silicon carbide ceramic treated in the step 2) into the aluminum-based alloy melt in the molten state prepared in the step 1, infiltrating for 0.5-9h at the temperature of 700-₃SiC₂a/SiC/Al composite material;

(4) and (3) an oxidation treatment process: the Ti polished in the step (3) is added₃SiC₂the/SiC/Al composite material is put into a porcelain boat, then put into a box furnace for in-situ oxidation treatment at the oxidation temperature of 800-₃SiC₂-Al₂O₃-SiC-Al composite material.

The concentration of the NaOH solution in the step (1) is 0.3-0.6 mol/L.

The invention provides a Ti prepared by the method₃SiC₂-Al₂O₃-SiC-Al composite material, the outer layer of the composite material is Ti₃SiC₂/Al₂O₃The interior of the/SiC reaction layer is a compact SiC/Al composite material.

The method is further characterized in that Ti content, infiltration temperature, heat preservation time, oxidation temperature and oxidation time in the aluminum alloy are adjusted to effectively control Ti₃SiC₂/Al₂O₃In-situ generation process on the SiC surface; the melting point and the alloy fluidity of the aluminum alloy and the wettability of the aluminum alloy and SiC ceramic can be effectively controlled by adjusting the contents of Ti, Si and Mg in the aluminum alloy.

The SiC ceramics, aluminum, titanium, silicon, magnesium and the like used in the method of the present invention are commercially available. The raw material of the aluminum is pure aluminum ingot, the raw material of the titanium is pure titanium ingot, titanium powder or titanium rod, the raw material of the silicon is silicon block, and the raw material of the magnesium is magnesium powder.

The invention has the substantive characteristics that:

the invention adopts a one-step in-situ oxidation treatment process to remove Ti on the outer surface₃SiC₂Al generated by Al in-situ oxidation in the gap with SiC₂O₃To change the surface layer into Ti₃SiC₂/Al₂O₃A great deal of research and experiments show that the temperature of the reaction layer of the/SiC is too low, the oxidation reaction of aluminum is insufficient, the antifriction and wear-resistant effects are poor, the temperature is too high, and the newly generated lubricating phase Ti is easy to react₃SiC₂And the SiC matrix is oxidized and damaged, so the invention explores the optimal infiltration process parameters and in-situ oxidation process parameters and prepares the Ti with the optimal antifriction and wear-resistant effects₃SiC₂-Al₂O₃-SiC-Al composite material.

The invention has the beneficial effects that:

previously proposed containing Ti₃SiC₂And Al₂O₃The SiC-based self-lubricating composite material still stays on powder hot-pressing sintering and ceramic/ceramic composite materials, the powder bonding property is poor, the improvement of the obdurability is limited, the hardness is low, the improvement of the wear resistance is small, the implementation mode is complex, the period is long, the energy consumption is high, and the cost is high. The preparation method of the invention adjusts the contents of the auxiliary elements Ti, Si and Mg to prepare the Al-based alloy with low melting point, good fluidity and good wettability with SiC ceramic. After the infiltration is finished, the sample is polished to obtain Ti preliminarily₃SiC₂The method comprises the following steps of carrying out in-situ oxidation treatment on aluminum existing in gaps by adopting a heat treatment process of in-situ oxidation, and searching newly generated Ti by fully oxidizing the aluminum in the gaps through regulating oxidation temperature and oxidation time and repeating experiments₃SiC₂Optimum heat treatment technological parameters for preventing lubricating phase from being oxidized and decomposed, under the condition of said technological parameters, the obtained composite material external surface layer is made up by using Ti₃SiC₂-Al₂O₃-SiC, with the interior consisting of dense SiC/Al. The composite material prepared by the invention has high toughness and good frictional wear performance. From example 6, it can be seen that the alloy can be made to completely penetrate the ceramic by controlling the infiltration time and infiltration temperature, and that the oxidation temperature and oxidation time can be controlledThe thickness of the reaction layer is controlled, the maximum thickness of the reaction layer is 400 mu m, and the fracture toughness of the composite material obtained by the preparation method is 5.9MPam^1/2Compared with the original SiC ceramic (2.2 MPam)^1/2) Improved by 3.7MPam^1/2The fracture toughness is improved by nearly 168 percent to the maximum extent. The friction and wear performance test is carried out under the same condition, the average friction coefficient of the material is 0.30, and the average wear rate is 3.2 multiplied by 10^-3mm³Min, compared to the original SiC ceramic (coefficient of friction 0.55, rate of wear 5X 10)^-3mm³Min), the friction coefficient is reduced by 0.25 and is nearly reduced by 45 percent, and the wear rate is reduced by 1.8 multiplied by 10 relative to the original SiC ceramic^-3mm³The/min is reduced by approximately 36 percent, the oxidation treatment method has simple steps and low cost, can effectively improve the toughness and the antifriction and wear-resistant performance of the SiC ceramic, and is suitable for large-scale popularization.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 shows Ti of the present invention₃SiC₂-Al₂O₃Preparation of-SiC-Al composite Material Ti obtained in example 6₃SiC₂-Al₂O₃SEM image of the surface of the SiC-Al composite material.

FIG. 2 shows Ti of the present invention₃SiC₂-Al₂O₃Preparation of-SiC-Al composite Material Ti obtained in example 6₃SiC₂-Al₂O₃-surface XRD pattern of SiC-Al composite material.

FIG. 3 shows Ti of the present invention₃SiC₂-Al₂O₃Preparation of-SiC-Al composite Material Ti obtained in example 6₃SiC₂-Al₂O₃EDS diagram of the surface of the SiC-Al composite material.

FIG. 4 shows Ti of the present invention₃SiC₂-Al₂O₃Preparation of-SiC-Al composite Material Ti obtained in example 6₃SiC₂-Al₂O₃SEM image at the center of the-SiC-Al composite material.

FIG. 5 shows Ti of the present invention₃SiC₂-Al₂O₃Preparation of-SiC-Al composite Material Ti obtained in example 6₃SiC₂-Al₂O₃EDS diagram at the center of the-SiC-Al composite material.

Detailed Description

The present invention will be further described with reference to the following examples and drawings, but the scope of the claims of the present application is not limited thereto.

Ti of the invention₃SiC₂-Al₂O₃A method for preparing an-SiC-Al composite material, the method comprising the steps of:

1) preparing an Al-based alloy: the Al-based alloy comprises the following elements in percentage by mass: al, 45-90 wt.%; ti, 3-25 wt.%; mg,1-6 wt.%; si, 5-30 wt.%;

weighing corresponding raw materials according to the mass percent of the elements, putting a pure aluminum ingot into 0.5mol/L NaOH solution, after 1-3 hours, completely removing surface oxide skin, putting the pure aluminum ingot into a graphite crucible, then putting the pure aluminum ingot, magnesium powder and silicon block into the graphite crucible together, then putting the graphite crucible into an energy-saving box type resistance furnace with the model of SX-G04132, heating to 700-1100 ℃, melting, preserving heat for 0.5-4 hours, and stirring until the pure aluminum ingot is completely dissolved, thus obtaining Al-based alloy liquid in a molten state;

2) and (3) processing the SiC ceramic: cutting the SiC ceramic raw material into required size by a diamond cutting machine; respectively polishing the SiC surface by using 800-mesh, 1500-mesh and 3000-mesh diamond millstones until the surface is smooth and has no oxidation layer, and placing the SiC surface in acetone and absolute ethyl alcohol for ultrasonic cleaning; circulating for 4 times, and finally drying for later use;

3) and (3) infiltration process: immersing the SiC ceramic treated in the step 2) into the Al-based alloy liquid in a molten state prepared in the step 1), putting the SiC ceramic into a box-type furnace for heat preservation at the infiltration temperature of 700-1000 ℃ for 0.5-9h, taking out a sample, cooling the sample to room temperature, and then polishing the surface to obtain Ti preliminarily₃SiC₂a/SiC/Al composite material.

4) An in-situ oxidation treatment process: the Ti polished in the step 3) is added₃SiC₂Putting the/SiC/Al composite material into a ceramic boat, and thenPutting the sample into a box furnace for in-situ oxidation treatment at the oxidation temperature of 800-₃SiC₂-Al₂O₃-SiC-Al composite material.

The invention provides a Ti prepared by the method₃SiC₂-Al₂O₃-SiC-Al composite material, the outer layer of the composite material is Ti-containing₃SiC₂/Al₂O₃The reaction layer of/SiC, the inside is SiC/Al composite material.

The preparation method is further characterized in that Ti and Al in the aluminum alloy are remained, the infiltration temperature and time and the in-situ oxidation temperature and time are adjusted, so that Ti can be effectively controlled₃SiC₂And Al₂O₃In the in-situ formation process of the SiC surface layer, under the condition, the outer Ti layer of the composite material₃SiC₂And Al₂O₃The reaction layer is compact and uniform, and the fracture toughness and the antifriction and wear-resistant performance are good. The melting point and the fluidity of the Al-based alloy and the wettability of the Al-based alloy and SiC can be controlled by adjusting the contents of Si and Mg in the Al-based alloy.

SiC ceramic used in the present invention (produced by Huamei Fine ceramics Co., Ltd., Shandong province, having a density of 3.02 g/cm)³SiC ceramics with porosity of 1.48%), Al, Ti, Si, Mg and the like are commercially available, the raw material of the metal aluminum is an aluminum ingot, the raw material of the silicon is a silicon block, the raw material of the Mg is pure magnesium powder, and the raw material of the titanium is titanium powder or a titanium ingot.

Example 1

Example Ti₃SiC₂-Al₂O₃The preparation method of the-SiC-Al composite material comprises the following steps:

1) preparing the aluminum-based alloy: the aluminum-based alloy comprises the following elements in percentage by mass: al, 78 wt%; 10 wt% of Ti; mg, 2 wt%; si, 10 wt%;

weighing corresponding raw materials according to the mass percent of the elements, wherein the raw materials are respectively Al ingot (with the purity of 99.9%), Ti ingot (with the purity of 99.9%), Mg powder (with the purity of 99.9%) and Si block (with the purity of 99.5%), putting the pure aluminum ingot into 0.5mol/L NaOH solution, after 2 hours, completely removing surface oxide skin, taking 156G of Al ingot, putting the 156G of Al ingot into a graphite crucible, then putting 20G of Ti, 20G of Si and 4G of Mg into the graphite crucible together, putting the graphite crucible into an energy-saving box type resistance furnace with the model of SX-G04132, heating to 800 ℃, heating rate to 20 ℃/min, preserving heat at the temperature for 45min, and stirring until the Al-based alloy liquid in a molten state is obtained.

2) And (3) processing the SiC ceramic: cutting a SiC ceramic raw material into a plurality of sample strips with the size of 40mm multiplied by 5mm (used for a fracture toughness test) and the size of 25mm multiplied by 5mm (used for a friction wear test) by a diamond cutting machine; respectively polishing the SiC surface by using 800-mesh and 1500-mesh diamond millstones until the surface is smooth and has no oxide layer, and placing the SiC surface in acetone and absolute ethyl alcohol for ultrasonic cleaning; circulating for 4 times, and finally drying for later use;

3) and (3) infiltration process: immersing the SiC ceramic treated in the step 2) into the molten Al-based alloy liquid prepared in the step 1), carrying out infiltration in an energy-saving box type resistance furnace with the model of SX-G04132, wherein the infiltration temperature is 900 ℃, the infiltration time is 4h, taking out a sample after the infiltration is finished, cooling the sample to room temperature, polishing the surface, and preliminarily obtaining Ti₃SiC₂a/SiC/Al composite material.

4) An in-situ oxidation treatment process: ti preliminarily obtained in the step 3)₃SiC₂Putting the/SiC/Al composite material into a ceramic boat, then putting the ceramic boat into a box-type furnace for in-situ oxidation treatment at the oxidation temperature of 950 ℃ for 8 hours, taking out a sample after the oxidation is finished, and cooling the sample to room temperature to obtain Ti₃SiC₂-Al₂O₃-SiC-Al composite material.

For the obtained Ti₃SiC₂-Al₂O₃the-SiC-Al composite material is subjected to fracture toughness test and frictional wear test, and the specific process is as follows:

taking the obtained Ti₃SiC₂-Al₂O₃5 parallel samples of 40mm x 5mm size of-SiC-Al composite material are prepared by grinding aluminum alloy adhered to the surface with corundum grinding wheel, and sequentially grinding the samples with 150-mesh, 400-mesh and 1500-mesh sandpaperPolishing and flattening the surface, ultrasonically cleaning the surface for 4min by absolute ethyl alcohol, circulating for 4 times, drying, selecting 5 samples, prefabricating a prefabricated crack with the width of 0.2mm and the depth of 2mm at the middle position by using a diamond cutting machine for fracture toughness test, wherein the average fracture toughness of the samples is 5.1MPam^1/2Compared with the original SiC ceramic (2.2 MPam)^1/2) Improved by 2.9MPam^1/2(ii) a Selecting 5 samples with size of 25mm × 25mm × 5mm, testing friction and wear performance of the samples with SFT-2M pin-disc friction and wear tester, and testing with Si with diameter of 4mm₃N₄The ceramic ball is used as a friction pair, the room temperature is 25 ℃, the rotating speed is 200r/min, the load is 5N, the abrasion time is 20min, and the friction rotating radius is 3 mm. Under the condition, the average friction coefficient of the material is measured to be 0.4, and the average wear rate is 4 multiplied by 10^-3mm³Min, compared to the original SiC ceramic (coefficient of friction 0.55, rate of wear 5X 10)^-3mm³Min), the friction coefficient is reduced by 0.15, and the wear rate is reduced by 1 multiplied by 10^-3mm³And/min. The original SiC ceramic herein refers to the SiC ceramic raw material in step 2.

The preparation method of this example can obtain Ti₃SiC₂-Al₂O₃The SiC-Al composite material can enable Al to completely permeate into SiC ceramic when the infiltration time is 4 hours, and Ti is gathered on the surface layer of SiC and reacts to generate relatively compact Ti₃SiC₂The in-situ oxidation time of the layer is 8h, so that most Al in the pores is oxidized to form relatively compact Ti on the surface layer₃SiC₂-Al₂O₃-a SiC layer.

Example 2

Example Ti₃SiC₂The specific steps of the preparation method of the/SiC/Al composite material are the same as those of the embodiment 1, and the difference is that the aluminum-based alloy comprises the following elements in percentage by mass: al, 83 wt%; 5 wt% of Ti; mg, 2 wt%; si, 10 wt%.

The composite material prepared in this example was analyzed according to the test and analysis procedures of example 1, with the following results: the composite material prepared in this example had an average fracture toughness of 4.3MPam as measured by fracture toughness testing^1/2Compared withFrom virgin SiC ceramic (2.2 MPam)^1/2) Improved by 2.1MPam^1/2(ii) a The friction and wear performance test is carried out under the same condition, and the average friction coefficient of the material is 0.45 and the average wear rate is 4.2 multiplied by 10^-3mm³Min, compared to the original SiC ceramic (coefficient of friction 0.55, rate of wear 5X 10)^-3mm³Min), the friction coefficient is reduced by 0.1, and the wear rate is reduced by 0.8 multiplied by 10^-3mm³And/min. The original SiC ceramic herein refers to the SiC ceramic raw material in step 2.

The preparation method of this example can obtain Ti₃SiC₂-Al₂O₃And the SiC-Al composite material can completely permeate Al into the SiC ceramic when the infiltration time is 4 hours, but the lower titanium content in the aluminum alloy can not lead Ti to be fully gathered on the SiC surface layer, so the surface layer structure is not compact, and a large amount of SiC which is not completely reacted is still included.

Example 3

In this example, Ti₃SiC₂-Al₂O₃The specific preparation method and steps of the-SiC-Al composite material are the same as those of the embodiment 1, except that the mass percentages of the elements in the aluminum alloy in the embodiment are as follows: al, 75 wt.%; ti, 10 wt.%; mg, 5 wt%; si, 10 wt%.

The composite material obtained in this example was analyzed according to the procedure of example 1, and as a result, the average fracture toughness of the composite material obtained in this example was 5.2MPam according to the fracture toughness test^1/2Compared with the original SiC ceramic (2.2 MPam)^1/2) Improved by 3.0MPam^1/2(ii) a The friction and wear performance test is carried out under the same condition, the average friction coefficient of the material is 0.42, and the average wear rate is 4.0 multiplied by 10^-3mm³Min, compared to the original SiC ceramic (coefficient of friction 0.55, rate of wear 5X 10)^-3mm³Min), the friction coefficient is reduced by 0.13, and the wear rate is reduced by 1.0 multiplied by 10^-3mm³/min。

The preparation method of this example can obtain Ti₃SiC₂-Al₂O₃-SiC-Al composite material and has been impregnated for 4hBy completely penetrating Al into the SiC ceramic, the higher Mg content in the aluminum alloy greatly improves the fluidity of the alloy liquid and promotes Ti to be fully enriched on the SiC surface layer, so that the surface layer structure is more compact and the reaction layer thickness is larger than that in the embodiment 3.

Example 4

Example Ti₃SiC₂The specific steps of the preparation method of the/SiC/Al composite material are the same as those in the embodiment 3, except that the mass percentages of the elements in the aluminum alloy in the embodiment are as follows: al, 70 wt.%; ti, 15 wt.%; mg, 5 wt%; si, 10 wt%.

The composite material prepared in this example was analyzed according to the test and analysis procedures of example 3, with the following results: the composite material prepared in this example had an average fracture toughness of 5.4MPam as measured by fracture toughness testing^1/2Compared with the original SiC ceramic (2.2 MPam)^1/2) Improved by 3.2MPam^1/2(ii) a The friction and wear performance test is carried out under the same condition, the average friction coefficient of the material is 0.38, and the average wear rate is 3.8 multiplied by 10^-3mm³Min, compared to the original SiC ceramic (coefficient of friction 0.55, rate of wear 5X 10)^-3mm³Min), the friction coefficient is reduced by 0.17, and the wear rate is reduced by 1.2 multiplied by 10^-3mm³/min。

The preparation method of this example can obtain Ti₃SiC₂-Al₂O₃The oxidation time of the-SiC-Al composite material is 8h, most of Al remained on the surface layer can be oxidized into Al₂O₃And sufficient titanium content enables Ti to be fully gathered on the SiC surface layer, so the surface layer structure is compact.

Example 5

Example Ti₃SiC₂The specific steps of the preparation method of the/SiC/Al composite material are the same as those of the embodiment 3, except that the oxidation time of the embodiment is 6 h.

The composite material prepared in this example was analyzed according to the test and analysis procedures of example 3, with the following results: the composite material prepared in this example had an average fracture toughness of 4.4MPam as measured by fracture toughness testing^1/2Compared with the original SiC ceramic (2.2 MPam)^1/2) Improved by 2.2MPam^1/2(ii) a The friction and wear performance test is carried out under the same condition, the average friction coefficient of the material is 0.46, and the average wear rate is 4.3 multiplied by 10^-3mm³Min, compared to the original SiC ceramic (coefficient of friction 0.55, rate of wear 5X 10)^-3mm³Min), the friction coefficient is reduced by 0.09, and the wear rate is reduced by 0.7 multiplied by 10^-3mm³/min。

The preparation method of this example can obtain Ti₃SiC₂-Al₂O₃The SiC-Al composite material can oxidize the Al remained on the surface layer into Al when the oxidation time is 6h₂O₃However, since the aluminum in the pores inside the ceramic was not oxidized sufficiently as in the case of the aluminum in example 3, the surface layer structure was not dense, and unreacted Al was still included.

Example 6

Example Ti₃SiC₂The specific steps of the preparation method of the/SiC/Al composite material are the same as those of the embodiment 3, except that the oxidation time of the embodiment is 10 h.

The composite material prepared in this example was analyzed according to the test and analysis procedures of example 3, with the following results: the composite material prepared in this example had an average fracture toughness of 5.9MPam as measured by fracture toughness testing^1/2Compared with the original SiC ceramic (2.2 MPam)^1/2) Improved by 3.7MPam^1/2(ii) a The friction and wear performance test is carried out under the same condition, the average friction coefficient of the material is 0.30, and the average wear rate is 3.2 multiplied by 10^-3mm³Min, compared to the original SiC ceramic (coefficient of friction 0.55, rate of wear 5X 10)^-3mm³Min), the friction coefficient is reduced by 0.25, and the wear rate is reduced by 1.8 multiplied by 10^-3mm³/min。

The obtained Ti₃SiC₂-Al₂O₃Sequentially carrying out surface grinding on the-SiC-Al composite material by using 150-mesh, 400-mesh, 800-mesh, 1500-mesh and 2000-mesh sand paper to remove Al-based alloy adhered to the surface, ultrasonically cleaning the Al-based alloy by using absolute ethyl alcohol for 4min, and drying the cleaned Al-based alloy; XRD detection and SEM and EDS analysis of the surfaceThe specific results are shown in FIG. 1, FIG. 2 and FIG. 3, respectively, and the area with the largest area in FIG. 1 represents Ti₃SiC₂Phase, white region represents Al₂O₃Phase, the darkest small fragment-like region represents the SiC phase. As can be seen from FIG. 1, the outer layer (interface) of the composite material has a large amount of Ti₃SiC₂And Al₂O₃Formation of very small amounts of SiC, in this case Ti₃SiC₂-Al₂O₃Ti of-SiC-Al composite material₃SiC₂And Al₂O₃The layer is the most dense. Through a metallographic microscope with the model of OLMYMPUS DSX510, by utilizing multiphase content measurement ASTME 1245-2003 software, according to the difference of gray values of different phases, the volume percentage Ti of each component in the embodiment is measured₃SiC₂：57％，Al₂O₃：35％，SiC：8％。

For Ti₃SiC₂-Al₂O₃The blocks of-SiC-Al composite material were cross-sectioned with 150 mesh, 400 mesh, 800 mesh, 1500 mesh, 2000 mesh diamond disks, polished with 0.5 μm polishing agent, and subjected to SEM and EDS analysis of the center of the cross-section, as shown in FIGS. 4 and 5, respectively. Fig. 4 shows that the internal structure of the SiC ceramic is dense, and fig. 5 shows that the elements Si, C, and Al are mainly present inside the composite material, which indicates that Al completely penetrates the SiC ceramic and forms a dense structure with SiC particles.

The preparation method of this example can obtain Ti₃SiC₂-Al₂O₃The oxidation time of the-SiC-Al composite material is 10h, so that the Al remained in the surface pores can be completely oxidized into Al₂O₃While other phases are not damaged, Ti is fully accumulated on the SiC surface layer and completely reacts to generate a large amount of Ti₃SiC₂The thickness of the reaction layer can reach 400 μm, so the surface layer structure is the most compact, the toughness is the highest, and the antifriction and wear-resistant effects are the best.

The following conclusions can be drawn by comparison of examples 1 to 6: the increase of Ti content contributes to Ti in the surface layer₃SiC₂The addition of Ti, Mg and Si in the Al alloy helps to improve the flow of the alloy liquidMobility, so that the infiltration depth is increased, preferably the oxidation temperature is 950 ℃, and Ti is added along with the extension of the oxidation time (6h-10h)₃SiC₂-Al₂O₃The thickness of the-SiC reaction layer is increased, the best effect is achieved in example 6, the maximum thickness of the reaction layer can reach 400 mu m, and the maximum fracture toughness can reach 5.9MPam^1/2The friction coefficient is reduced to 0.30, and the wear rate is reduced to 3.2 multiplied by 10^-3mm³/min。

Table 1 shows example 6Ti₃SiC₂-Al₂O₃The fracture toughness, the friction coefficient and the wear rate of the-SiC-Al composite material are compared with those of the original ceramic.

Sample (I)	Fracture toughness (MPam)^1/2)	Coefficient of friction	Wear rate (mm)³/min)
				SiC ceramics	2.2	0.55	5×10^-3
Example 6	5.9	0.30	3.2×10^-3

In conclusion, the invention adopts the wettability of the elements Al, Ti, Si and Mg and the ceramicIntroducing Al-based alloy into the SiC ceramic by a reaction infiltration method to form a compact SiC/Al structure inside, and simultaneously generating a layer on the outer surface of the SiC ceramic and simultaneously containing Ti₃SiC₂A metal ceramic layer of SiC and Al, polishing the surface of the sample after infiltration, putting the sample in an electric furnace, carrying out further heat treatment, namely carrying out in-situ oxidation treatment on the preliminarily obtained composite material for a certain time at a certain temperature, and carrying out Ti treatment on the outer surface₃SiC₂Al generated by Al in-situ oxidation in the gap with SiC₂O₃Thus obtaining an outer surface layer of Ti₃SiC₂/Al₂O₃SiC, Ti with dense SiC/Al inside₃SiC₂-Al₂O₃The method obviously improves the toughness, the friction reduction and the wear resistance of the SiC-based composite material; the preparation method can be completed under normal pressure, in-situ generation is realized, the preparation process is simplified, the material interface bonding strength is high, the compatibility is good, the defect that the preparation can only be carried out under harsh process conditions such as high pressure and even high vacuum in the prior art is overcome, the production cost is greatly reduced, and the size net molding can be realized. The preparation process can be finished under normal pressure, the operation process is simple, the size net forming can be realized, and the method is suitable for industrial implementation and practical application, and is particularly suitable for the field of working conditions requiring high strength and high wear resistance.

The comparison of the above embodiments is intended to facilitate the understanding of the trend of the product performance in the preparation method of the present invention in terms of the adjustment of the process parameters. So that those skilled in the art can clearly understand the innovative nature of the technical solution of the present invention, embodiments are not presented only in terms of functions or product performance. Thus, the present invention can be implemented in other various ways in addition to the above-described embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.

Nothing in this specification is said to apply to the prior art.

Claims

1. Ti₃SiC₂-Al₂O₃-SiC-Al composite material, characterized in that the outer layer of the composite material isTi obtained by adopting in-situ oxidation heat treatment process₃SiC₂/Al₂O₃the/SiC reaction layer is internally provided with a SiC/Al composite material and is prepared by infiltrating a SiC matrix with aluminum alloy; the thickness of the reaction layer is 100-400 μm;

in the outer layer of the composite material, the volume percentage of Ti₃SiC₂：60~80%，Al₂O₃：15%~40%，SiC：5%~20%。

2. The Ti of claim 1₃SiC₂-Al₂O₃-SiC-Al composite material, characterized in that it comprises the following steps:

(1) preparing the aluminum-based alloy: the aluminum-based alloy comprises the following elements in percentage by mass: al, 45-90 wt.%; ti, 3-25 wt.%; mg,1-6 wt.%; si, 5-30 wt.%;

weighing corresponding raw materials according to the mass percent of the elements, immersing a pure aluminum ingot in NaOH solution for 1-3 hours, removing surface oxide skin, then placing the pure aluminum ingot, the magnesium powder and the silicon block in a graphite crucible, heating to 700-1100 ℃ for melting, and keeping the temperature for 0.5-4 hours under stirring to obtain molten aluminum-based alloy melt;

(2) pretreatment of SiC ceramic: cutting the SiC ceramic into required size, polishing, ultrasonically cleaning and drying;

3. Ti according to claim 2₃SiC₂-Al₂O₃The preparation method of the-SiC-Al composite material is characterized in that the concentration of the NaOH solution in the step (1) is 0.3-0.6 mol/L.