A high-toughness layered structure TiC x / Ti-based composite material and method for manufacturing the same

Abstract

The application provides a high-toughness layered structure TiC x / Ti-based composite material and a preparation method thereof, wherein the preparation method comprises the following steps: step S1, preparing a substrate, the substrate being a Ti-containing foil; step S2, preparing a Ti-Ti3AlC2 composite layer sheet, the composite layer sheet being prepared from a Ti and Ti3AlC2-containing powder slurry through an organic tape casting method; step S3, alternately stacking the Ti-Ti3AlC2 composite layer sheet and the substrate in multiple layers to obtain a laminate; and step S4, performing hot-pressing sintering on the laminate to obtain a high-toughness layered structure TiC x / Ti-based composite material. According to the preparation method of the embodiment of the application, Ti3AlC2 is in-situ generated through hot-pressing sintering x , and the A-site Al atoms are alloyed with Ti, thereby playing a performance strengthening effect. The high-toughness layered structure TiC x / Ti-based composite material according to the embodiment of the application has a bending strength of up to 1358 MPa and a fracture toughness of up to 31.87 MPa·m 1 / 2 , and has high strength and high toughness.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of new material preparation, and particularly relates to a high-strength and high-toughness layered structure TiC x / Ti-based composite material and a preparation method thereof. BACKGROUND

[0002] Titanium-based composite material is a new type of metal-based composite material developed in the 1950s. Compared with titanium alloy, it has higher specific strength and specific elastic modulus, excellent high-temperature resistance and corrosion resistance, and overcomes the shortcomings of poor wear resistance and poor combustion resistance of titanium alloy, so it is considered to be a new material capable of improving the performance of titanium materials and expanding the application of titanium alloy, and has broad application prospects in many fields such as aerospace, ships, automobiles and national defense.

[0003] Titanium-based composite material is mainly prepared by taking titanium or titanium alloy as a matrix and taking ceramic phase (particle, whisker, fiber) as a reinforcing body. The performance of the obtained material mainly depends on the characteristics, distribution and content of the matrix and the reinforcing body, and the optimization of the combination of the reinforcing body and the matrix is a decisive factor for preparing high-performance titanium-based composite material.

[0004] Among them, Ti3AlC2 is a structural ceramic with excellent performance, which is a member of 312 phase in the M n+1 AX n phase (also known as MAX phase) material system, which combines some excellent properties of metals and ceramics. The ceramic itself has characteristics such as toughness and machinability similar to metals, good electrical conductivity, and good high-temperature mechanical properties and corrosion resistance at room temperature. There have been many reports on MAX reinforced metal matrix composites. The hardness, strength and wear resistance of the composite material reinforced by the MAX phase are greatly improved. The excellent performance of the ceramic makes it a good choice as a reinforcing phase of titanium-based composite material.

[0005] For a long time, based on the traditional research idea of metal matrix composite material, most researchers always pursue the uniform distribution of the reinforcing phase in the titanium matrix, and strive to improve the mechanical properties of the titanium-based composite material by increasing the content of the reinforcing phase. Although the strength and stiffness of the titanium-based composite material are significantly improved, the plasticity and toughness are significantly reduced, that is, the strength-toughness (plasticity) of the traditional titanium-based composite material is in an inverted relationship. Engineering practical applications often require titanium-based composite materials not only to have high strength and stiffness, but also to have good plasticity and impact resistance. At present, the lack of plasticity and toughness of titanium-based composite material greatly limits its wide application in the industrial field. Therefore, it is imperative to develop titanium-based composite materials with high strength and toughness (strength is improved while maintaining sufficient plasticity and toughness). SUMMARY

[0006] The inventors found that in nature, a variety of organisms have chosen the most suitable materials to build tissues in a specific way after long-term natural screening, such as bamboo, butterfly wings, shells and the like. Among them, it is found that the chemical composition of the nacreous layer of shell organisms is very simple, mainly flaky calcium carbonate crystals, plus a small amount of organic matter, which is stacked according to a complex and delicate bricklaying microstructure, which can significantly improve the overall toughness, and the fracture work can be more than 3000 times that of pure calcium carbonate crystals. With the deepening of the study of biological materials, it is found that these materials have various excellent properties, which has important reference significance for preparing new high-performance titanium-based composite materials by using bionic means.

[0007] On the other hand, the inventors found through repeated research and a large number of experiments that the chemical bond characteristics of the MAX phase material are relatively special: strong covalent bonds and ionic bonds connect M and X atoms, and weak covalent bonds and metal bonds connect M and A atoms. Because the A-site atoms are weakly combined, they are easy to desolvate into the matrix during the metal material composite process, leaving the MX phase. Taking Ti3AlC2 material as an example, if Ti3AlC2 desolvates Al at the A site, non-stoichiometric TiC x is generated, which has good wettability with the Ti matrix; at the same time, the desorbed Al enters the Ti matrix, which can strengthen the Ti matrix.

[0008] Further, based on the multi-scale and multi-level toughening mechanism research of the natural biological shell nacreous layer, combined with the chemical bond characteristics of Ti3AlC2 material, the inventors researched and prepared a layered structure TiC x / Ti-based composite material obtained by sintering the layer-by-layer structure of Ti3AlC2 and Ti matrix, and through the optimization design of the interlayer structure and the combination of the flaky toughening mechanism, the good combination of strength and toughness can be realized, and the present application is completed on this basis.

[0009] The present application aims to provide a high-strength and high-toughness layered structure TiC x / Ti-based composite material and a preparation method thereof.

[0010] The preparation methods of the existing layered titanium-based composite materials mainly include the following according to the different process properties: explosive composite method, rolling composite method, hot pressing diffusion method and deposition composite method. The composite methods of the layered structure are: (1) stacking of alternating powder layers and powder layers; (2) stacking of alternating flaky layers and flaky layers. The existing problems are: it is difficult to control the uniformity of the layers, impurities are easily introduced between the layers, and it is difficult to recover the mixture between different powder layers during the process of alternating powder layer stacking; the process flow of the process of slicing and depositing the block material prepared first is complex and the cost is high.

[0011] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0012] The high-toughness layered structure TiC according to the first aspect of the present application x A preparation method of a Ti / Ti-based composite material, comprising the following steps:

[0013] Step S1, preparing a substrate, the substrate being a Ti-containing foil;

[0014] Step S2, preparing a Ti-Ti3AlC2 composite layer sheet, the composite layer sheet being prepared from a Ti-containing and Ti3AlC2-containing powder slurry through an organic tape casting method;

[0015] Step S3, alternately stacking the Ti-Ti3AlC2 composite layer sheet and the substrate in multiple layers to obtain a laminate;

[0016] Step S4, performing hot-press sintering on the laminate to obtain a high-toughness layered structure TiC x / Ti-based composite material.

[0017] Further, the material of the Ti-containing foil is any one of pure Ti, TC4 titanium alloy, and TA15 titanium alloy, and the thickness of the Ti-containing foil is 30-100 μm.

[0018] Further, the step S2 comprises:

[0019] Step S21, weighing Ti3AlC2 powder and Ti powder and mixing the same to obtain a mixed powder;

[0020] Step S22, dissolving a binder in an organic solvent to obtain an organic solution containing the binder;

[0021] Step S23, adding the mixed powder into the organic solution and dispersing the same to obtain a slurry;

[0022] Step S24, coating the slurry on a substrate to form a coating layer on the substrate;

[0023] Step S25, drying the coating layer and demolding the same from the surface of the substrate to obtain the Ti-Ti3AlC2 composite layer sheet.

[0024] Further, the particle size of the Ti powder is 40-50 μm, the particle size of the Ti3AlC2 powder is 4-5 μm, the addition ratio of the Ti3AlC2 powder in the mixed powder is 5vol%-20vol% in terms of volume fraction, and the thickness of the Ti-Ti3AlC2 composite layer sheet is 800-1500 μm.

[0025] Further, in the step S21, the mixing is performed by a drum ball mill, wherein the ball-to-material ratio in the drum ball mill is (2-5):1, and the ball milling is performed at a rotating speed of 100-150 r / min for 20-25 h.

[0026] Further, the step S22 comprises:

[0027] The binder is dissolved in anhydrous ethanol solvent by dispersion, and stirring is performed until the binder is completely dissolved.

[0028] A plasticizer is added and stirring is continuously performed until the plasticizer is completely dissolved, so as to obtain the organic solution.

[0029] Further, the binder is polyvinyl butyral (PVB), and the plasticizer is dibutyl phthalate (DBP) or dioctyl phthalate (DOP) or a mixture of the two, wherein the content of the binder in the anhydrous ethanol is 4.5wt.%-5.5wt.%, and the addition amount of the plasticizer relative to the binder is (1-1.5):1.

[0030] Further, in the step S23, the content of the mixed powder in the slurry is 40wt.%-60wt.%, and the step S23 comprises:

[0031] The mixed powder is added into the organic solution, and ultrasonic dispersion is performed first, and then mechanical stirring is performed, so as to obtain the slurry with uniform dispersion.

[0032] Further, the step S4 comprises:

[0033] In the step S41, the laminated body is pre-pressed under the action of an axial mechanical pressure of 2-10 MPa, and the pressure is maintained for a predetermined time.

[0034] In the step S42, the pre-pressed laminated body is hot-pressed and sintered at a temperature of 1200-1400℃ and a pressure of 20-50 MPa for 1-3 h, so as to obtain the high-toughness layered structure TiC x / Ti-based composite material.

[0035] Further, the step S42 comprises: the pre-pressed laminated body is placed in a hot-pressing and sintering mold cavity, vacuum is drawn, and the temperature is raised to 600℃ at a temperature raising rate of 10℃ / min, and the vacuum is drawn for 60 min after the temperature is maintained at 600℃, then high-purity argon gas is introduced as a protective gas, and the temperature is continuously raised to 1200℃, and the pressure is applied when the temperature is 1350℃, and the pressure is 30 MPa, and the pressure is maintained for 90 min at the highest temperature of 1350℃, and then the furnace is cooled, so as to obtain the high-toughness layered structure TiC x / Ti-based composite material.

[0036] According to the high-toughness layered structure TiCx The Ti-based composite material is prepared by the preparation method of any one of the embodiments of the first aspect of the application, and has a high-strength and high-toughness layered structure TiC x The Ti-based composite material has a bending strength of 1300 MPa or more and a fracture toughness of 30 MPa·m 1 / 2 The above.

[0037] The above technical solution of the application has at least one of the following beneficial effects:

[0038] According to the preparation method of the embodiments of the application, compared with a homogeneous single titanium-based composite material, the layered structure can improve the toughness of the titanium-based composite material by deflecting cracks and absorbing fracture energy, and can exhibit good delayed fracture characteristics, and can achieve good matching of strength and toughness.

[0039] On the other hand, the Ti3AlC2 ternary layered MAX phase ceramic material has a unique A-site Al atom desolvation characteristic, and can generate TiC x The A-site Al atoms desolvated at the same time can be alloyed with Ti, thereby achieving a performance strengthening effect.

[0040] According to the high-strength and high-toughness layered structure TiC x The Ti-based composite material has a high-strength and high-toughness layered structure TiC x The Ti-based composite material has a bending strength of 1300 MPa or more and a fracture toughness of 30 MPa·m 1 / 2 The above. BRIEF DESCRIPTION OF DRAWINGS

[0041] The purposes, advantages and other characteristics of the application will become more apparent through reading the detailed description of the embodiments thereof with reference to the following drawings:

[0042] Figure 1 is a scanning electron microscope photo of a cross section of the composite material prepared in Example 1;

[0043] Figure 2 is a scanning electron microscope photo of a cross section of the composite material prepared in Example 2;

[0044] Figure 3 is an XRD spectrum of the composite material prepared in Example 1 and Example 2;

[0045] Figure 4 is a comparison diagram of quasi-static tensile properties of the composite material prepared in Example 1 and Example 2. DETAILED DESCRIPTION

[0046] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0047] The high-toughness layered structure TiC / Ti-based composite material according to the embodiments of the present application will be described in detail first below. x The preparation method of the high-toughness layered structure TiC / Ti-based composite material.

[0048] The preparation method of the high-toughness layered structure TiC / Ti-based composite material according to the embodiments of the present application comprises the following steps. x The preparation method of the high-toughness layered structure TiC / Ti-based composite material.

[0049] Step S1, preparing a substrate, which is a Ti-containing foil.

[0050] The material of the Ti-containing foil may be, for example, any one of pure Ti, TC4 titanium alloy or TA15 titanium alloy, and the thickness of the Ti-containing foil may be, for example, 30-100 μm. The foil is selected as the substrate, which is easy to arrange the layered structure in a direction and combine the interfaces between the layers. When the thickness of the Ti layer is relatively thick, the gradient fracture is likely to occur between the layers of the composite material, because the layered composite material has a typical size effect, that is, the thinner the layered material, the stronger the effect.

[0051] Step S2, preparing a Ti-Ti3AlC2 composite layer, which is prepared by an organic tape casting method using a slurry of Ti-containing and Ti3AlC2 powders.

[0052] That is, the composite layer of the mixed material of Ti powder and Ti3AlC2 powder is prepared. As for the preparation of the composite layer, the mixed powders may be pressed into a shape after dry mixing, or a slurry of the mixed powders may be prepared and then a coating layer is formed on a carrier by a coating method such as tape casting, spin coating or impregnation, and then the coating layer is stripped to obtain the composite layer.

[0053] In some embodiments of the present application, the step S2 comprises:

[0054] Step S21, weighing Ti3AlC2 powder and Ti powder and mixing them to obtain mixed powders.

[0055] That is, according to the designed content of each component, the Ti3AlC2 powder and the Ti powder are weighed and dry mixed to obtain the mixed powders.

[0056] Specifically, the Ti powder has a particle size of 40-50 μm, the Ti3AlC2 powder has a particle size of 4-5 μm, and the Ti3AlC2 powder in the mixed powder has an adding ratio of 5 vol%-20 vol% in terms of volume fraction. Among them, the Ti3AlC2 powder with a small particle size is easy to be uniformly distributed in the composite layer sheet, the adding ratio of the Ti3AlC2 powder in the mixed powder is not easy to be too large, the larger the adding ratio of the Ti3AlC2 powder, the more the content of the generated TiC x , and too many hard and brittle ceramic phase particles in the layer are easy to reduce the toughness of the composite material.

[0057] Further, in the step S21, the mixing is performed by a drum ball mill, wherein the ball-to-material ratio in the drum ball mill is (2-5):1, and the ball milling is performed at a rotating speed of 100-150 r / min for 20-25 h.

[0058] In the step S22, the binder is dissolved in an organic solvent to obtain an organic solution containing the binder.

[0059] Meanwhile, in order to make the coating have a certain mechanical strength, an organic solution containing a binder also needs to be prepared for dispersing the mixed powder.

[0060] In some embodiments of the present application, the step S22 comprises:

[0061] The binder is dissolved in anhydrous ethanol solvent by dispersion and stirring until completely dissolved.

[0062] A plasticizer is added and continuously stirred until completely dissolved to obtain the organic solution.

[0063] Further, the binder is polyvinyl butyral (PVB), and the plasticizer is dibutyl phthalate (DBP), wherein the content of the binder in the anhydrous ethanol accounts for 4.5 wt.%-5.5 wt.%, and the adding amount of the plasticizer relative to the binder is (1-1.5):1. Alternatively, dioctyl phthalate (DOP) can be used as the plasticizer. Among them, with the increase of the content of the binder, the viscosity of the slurry increases, which is helpful for the slurry casting, and the plasticizer mainly increases the flexibility of the cast sheet, so that the cast sheet can be cut into the required shape.

[0064] In the step S23, the mixed powder is added to the organic solution and dispersed to obtain a slurry.

[0065] That is to say, after the mixed powder and the organic solution are respectively prepared, the mixed powder is only needed to be added to the organic solution for sufficient dispersion, and then the slurry for preparing the coating can be obtained.

[0066] In some embodiments of the present application, the content of the mixed powder in the slurry is 40wt.%-60wt.% in step S23. If the content of the powder in the slurry is too low, the slurry is easy to flow and is not easy to be drawn into a shape; if the content of the powder is too high, the powder particles are easy to agglomerate, which will reduce the uniformity of the drawn sheet. Step S23 comprises:

[0067] The mixed powder is added into the organic solution, and then ultrasonic dispersion is performed, followed by mechanical stirring, to obtain the slurry with uniform dispersion.

[0068] More specifically, the ultrasonic dispersion time can be 20-30 min, and the mechanical stirring is performed at a speed of 250-350 r / min for 1.5-2.5 h.

[0069] Step S24, the slurry is coated on the substrate to form a coating layer on the substrate.

[0070] After obtaining the slurry, it only needs to be coated on the substrate to form a coating layer on the substrate.

[0071] For example, the substrate can be a material such as glass, ceramic, etc.

[0072] In addition, in order to facilitate subsequent demolding, a release agent can be pre-coated on the surface of the substrate.

[0073] In addition, the thickness of the coating layer can be adjusted by adjusting the doctor blade, and preferably, the thickness of the Ti-Ti3AlC2 composite sheet is set to 800-1500 μm.

[0074] Step S25, the coating layer is dried and demolded from the surface of the substrate to obtain the Ti-Ti3AlC2 composite sheet.

[0075] After the organic solvent in the coating layer is removed by drying and volatilization, it can be demolded from the surface of the substrate, and the Ti-Ti3AlC2 composite sheet can be obtained.

[0076] Step S3, the Ti-Ti3AlC2 composite sheet and the substrate are alternately stacked in multiple layers to obtain a laminate.

[0077] That is, the prepared substrate and Ti-Ti3AlC2 composite sheet are alternately stacked to form a laminate with multiple layers.

[0078] In the present application, the specific number of layers of the laminate is not particularly limited, and can be appropriately selected in combination with the thickness of the material and the thickness of each layer.

[0079] In addition, the outermost layer of the application is not particularly limited to the base layer or the Ti-Ti3AlC2 composite layer, and the outermost layer is preferably the base layer. Since the base layer is a Ti-containing foil, it has better mechanical strength than the Ti-Ti3AlC2 composite sheet, and can avoid unnecessary damage during transportation, pre-pressing and the like.

[0080] The high-toughness layered structure TiC x / Ti-based composite material, by designing the layered structure, compared with the homogeneous single titanium-based composite material, the deflection of the layered structure to the crack and the absorption of the fracture energy can improve the toughness of the titanium-based composite material, showing good delayed fracture characteristics, and can realize good matching of strength and toughness.

[0081] Step S4, hot-pressing sintering the laminate to obtain a high-toughness layered structure TiC x / Ti-based composite material.

[0082] After obtaining the laminate, hot-pressing sintering is performed, and in the sintering process, Ti3AlC2 is generated in-situ TiC x Meanwhile, the A-site Al atoms dissolved out and the Ti alloying effect, thereby playing a performance strengthening effect.

[0083] In some embodiments of the application, the step S4 comprises:

[0084] Step S41, pre-pressing the laminate under the action of an axial mechanical pressure of 2-10 MPa and for a predetermined time;

[0085] Step S42, hot-pressing sintering the pre-pressed laminate at 1200-1400℃ under a pressure of 20-50 MPa for 1-3h to obtain a high-toughness layered structure TiC x / Ti-based composite material.

[0086] Through pre-pressing, the laminate has certain strength and density, which is convenient for obtaining more uniform and dense composite material through subsequent hot-pressing sintering.

[0087] In some embodiments of the application, the step S42 comprises: placing the pre-pressed laminate into a hot-pressing sintering mold cavity, vacuumizing while heating at a heating rate of 10℃ / min to 600℃, and vacuumizing for 60min at 600℃, then introducing high-purity argon as a protective gas, continuing to heat to 1200℃, starting to pressurize, to 1350℃, pressurizing to 30MPa, and pressurizing for 90min at the highest temperature of 1350℃, and then cooling in the furnace to obtain a high-toughness layered structure TiC x / Ti-based composite material.

[0088] The high-toughness layered structure TiC according to the second aspect of the present application x The Ti / Ti3AlC2 composite material is prepared by the preparation method according to any one of the first aspect of the present application x The Ti / Ti3AlC2 composite material has a bending strength of 1300 MPa or more and a fracture toughness of 30 MPa·m 1 / 2 The above.

[0089] The preparation method and the high-toughness layered structure TiC according to the present application will be further described in detail below in combination with specific embodiments. x The Ti / Ti3AlC2 composite material is prepared by the preparation method according to any one of the first aspect of the present application

[0090] Example 1

[0091] A Ti3AlC2 precursor-reinforced layered structure titanium-based composite material with a volume fraction of 10 vol% of Ti3AlC2 in the composite layer sheet is prepared, and the specific steps are as follows:

[0092] 1. 90.6356 g of Ti powder and 9.3644 g of Ti3AlC2 powder are weighed, the particle size of the Ti powder is 40-50 μm, the particle size of the Ti3AlC2 powder is 4-5 μm, the mixed powder is put into a roller ball mill tank, the ball-to-material ratio is 5:1, and the roller ball mill tank is placed on a roller ball mill at a speed of 100 r / min for 20 h to make the mixture uniform.

[0093] 2. 5 g of PVB powder is added to 100 g of anhydrous ethanol solvent, and stirred by a magnetic stirrer until completely dissolved, and then the uniformly mixed powder is put into the completely dissolved PVB-ethanol solution, 5 g of DBP reagent is added, and ultrasonic dispersion is performed by an ultrasonic dispersion machine for 30 min, and then the mixed slurry is placed under a mechanical stirrer at a speed of 300 r / min for 2 h to make the mixture uniform.

[0094] 3. The prepared powder slurry is uniformly coated on a glass plate by a doctor blade, and the thickness of the composite layer sheet set by the doctor blade is 1000 μm; after the composite layer sheet coated on the glass plate is naturally dried for 30 min, the entire glass plate is immersed in water for 40 min, and then taken out and naturally dried for 1.5 h, the composite layer sheet can be separated from the glass plate, and the Ti-Ti3AlC2 composite layer sheet is cut according to the size of the mold for storage, and the Ti-Ti3AlC2 composite layer sheet is obtained.

[0095] ⑷Cut the 100 μm thick pure Ti foil according to the size of the mold, and then alternately stack it with the prepared Ti-Ti3AlC2 composite laminates into a layered structure. Pre-press the stacked laminates into a quasi-layered structure block with an axial mechanical pressure of 5 MPa, and pre-press for 5 min. Then, place it in a BN-coated hot-pressing sintering mold cavity, and sinter it into a layered structure by hot-pressing sintering. The specific parameters are as follows: vacuumize at the beginning of hot-pressing sintering, and heat to 600℃ at a rate of 10℃ / min. The temperature is measured by thermocouple. After 60 min of heat preservation at 600℃, stop vacuumizing, and introduce high-purity argon as a protective gas. When the temperature rises to 1200℃, start pressing, and press to 30 MPa at 1350℃. The pressure holding time at the highest temperature of 1350℃ is 90 min. After cooling in the furnace, take it out, and obtain the desired layered structure titanium-based composite material. The microstructure is shown in Figure 1 Figure 1 It can be seen that there is no obvious boundary between the layers, and the generated TiC x is distributed along the layers as a whole.

[0096] Finally, according to the national standard GB / T.6569-2006, cut the standard sample with a size of 3mm×4mm×36mm, of which the thickness direction is perpendicular to the layered direction. Set the pressure head descending speed to 0.5mm / min on the universal testing machine, and obtain the bending strength of the composite material as 1220MPa. Use the three-point bending single-edge notched beam method to cut the standard sample with a size of 5.5mm×3mm×25mm. Cut a single-edge notch in the middle of each sample span, with a width of 0.2mm and a depth of 2.5mm. Set the downward loading speed to 0.05mm / min on the universal testing machine, and obtain the fracture toughness of the composite material as 32.18MPa•m 1 / 2 .

[0097] Example 2

[0098] Prepare a layered structure titanium-based composite material with a volume fraction of 15vol% Ti3AlC2 precursor reinforced layer, and the specific steps are as follows:

[0099] ⑴ Weigh 85.9036g of Ti powder and 14.0964g of Ti3AlC2 powder. The particle size of the Ti powder is 40-50μm, and the particle size of the Ti3AlC2 powder is 4-5μm. Put the mixed powder into a roller ball mill jar, put maroon balls according to the ball-to-material ratio of 5:1, and put the roller ball mill jar on the roller ball mill at a speed of 100r / min for 20h to make it uniformly mixed.

[0100] ​(2) 5 g of PVB powder was added into 100 g of anhydrous ethanol solvent, and stirred by a magnetic stirrer until completely dissolved, and then the mixed powder was put into the completely dissolved PVB-ethanol solution, and 5 g of DBP reagent was added, and dispersed by an ultrasonic disperser for 30 min, and then the mixed slurry was stirred by a mechanical stirrer at a speed of 300 r / min for 2 h until mixed uniformly.

[0101] (3) The prepared powder slurry was uniformly coated on a glass plate by a doctor blade, and the thickness of the composite layer prepared by the doctor blade was 1000 μm. After the composite layer coated on the glass plate was naturally dried for 30 min, the whole glass plate was immersed in water for 40 min, and then taken out and naturally dried for 1.5 h, the composite layer was separated from the glass plate, and then cut according to the size of the mold to obtain the Ti-Ti3AlC2 composite layer for use.

[0102] (4) A 100 μm thick pure Ti foil was cut according to the size of the mold, and then stacked alternately with the prepared Ti-Ti3AlC2 composite layer to form a layered structure, and the stacked layers were pre-pressed into a quasi-layered structure block by a 5 MPa axial mechanical pressure, and the pre-pressing time was 5 min. Then the block was put into a BN-coated hot-pressing sintering mold cavity, and sintered by hot-pressing sintering. The specific parameters were as follows: vacuumizing from the beginning, and then heating at a rate of 10 ℃ / min to 600 ℃, and the temperature was measured by a thermocouple. After being kept at 600 ℃ for 60 min, the vacuumizing was ended, and high-purity argon was introduced as a protective gas. When the temperature was increased to 1200 ℃, the pressure was increased, and when the temperature was increased to 1350 ℃, the pressure was increased to 30 MPa. The pressure keeping time at the highest temperature of 1350 ℃ was 90 min, and then the block was taken out after furnace cooling to obtain the required layered titanium-based composite material. The microstructure thereof is shown in Figure 2 Figure 2 It can be seen that there is no obvious boundary between the layers, and the generated TiC x is distributed along the layers as a whole.

[0103] Finally, the standard sample with a size of 3 mm×4 mm×36 mm was cut according to the national standard GB / T.6569-2006, and the thickness direction was perpendicular to the layered direction. The bending strength of the composite material was 1358 MPa, which was obtained by setting the pressure head descending speed to 0.5 mm / min on a universal testing machine. The standard sample with a size of 5.5 mm×3 mm×25 mm was cut by a three-point bending single-edge notched beam method, and a single-edge notch was cut in the middle of each sample span, and the notch width was 0.2 mm and the depth was 2.5 mm. The fracture toughness of the composite material was 31.87 MPa·m 1 / 2 .

[0104] ​Example 3

[0105] The specific steps for preparing a layered titanium matrix composite material reinforced with a Ti3AlC2 precursor at a volume fraction of 20 vol% incorporated into the composite layers are as follows:

[0106] (1) Weigh 81.138g of Ti powder and 18.862g of Ti3AlC2 powder. The particle size of Ti powder is 40-50μm and the particle size of Ti3AlC2 powder is 4-5μm. Put the mixed powder into a roller mill jar, add agate balls at a ball-to-material ratio of 5:1, and place the roller mill jar on a roller mill and mill at a speed of 100r / min for 20h to make it evenly mixed.

[0107] (2) Add 5g of PVB powder to 100g of anhydrous ethanol solvent and stir with a magnetic stirrer until completely dissolved. Then, put the well-mixed powder into the completely dissolved PVB-ethanol solution, add 5g of DBP reagent, and ultrasonically disperse for 30min using an ultrasonic disperser. Then, place the mixed slurry under a mechanical stirrer and stir at 300r / min for 2h until it is well mixed.

[0108] (3) The prepared powder slurry is uniformly coated onto a glass plate using a scraper, wherein the scraper is set to a thickness of 1000 μm for the required composite layer. After the composite layer coated on the glass plate dries naturally for 30 min, the entire glass plate is immersed in water for 40 min, and then removed and allowed to dry naturally for 1.5 h. The composite layer can then be removed from the glass plate, cut and sealed according to the mold size to obtain the required Ti-Ti3AlC2 composite layer for later use.

[0109] (4) A 100μm thick pure Ti foil was cut to the mold size and then alternately stacked with the prepared Ti-Ti3AlC2 composite sheets to form a layered structure. The stacked sheets were pre-pressed into a quasi-layered structure block under a pre-pressure of 5MPa axial mechanical pressure for 5 minutes. It was then placed in a BN-coated hot-pressing sintering mold cavity and sintered using hot-pressing. Specific parameters were as follows: The hot-pressing sintering process began with vacuum evacuation, followed by a heating rate of 10℃ / min to 600℃ using thermocouples. After holding at 600℃ for 60 minutes, vacuum evacuation was stopped, and high-purity argon was introduced as a protective gas. Pressure was applied starting at 1200℃ and increased to 30MPa at 1350℃. The maximum holding time at 1350℃ was 90 minutes. The product was then cooled and removed from the furnace to obtain the desired layered titanium-based composite material. Its microstructure is as follows: Figure 2 As shown. By Figure 2 It can be seen that there are no obvious boundaries between the layers, and the generated TiC x It is distributed along the overall layer.

[0110] Finally, standard specimens with dimensions of 3mm × 4mm × 36mm were cut according to the national standard GB / T.6569-2006, with the thickness direction perpendicular to the lamellar direction. The indenter descent speed on the universal testing machine was set to 0.5mm / min, yielding a flexural strength of 1026MPa for the composite material. Standard specimens with dimensions of 5.5mm × 3mm × 25mm were cut using the three-point bending single-sided notch beam method. A single-sided notch was cut in the middle of each specimen span, with a width of 0.2mm and a depth of 2.5mm. The downward loading speed on the universal testing machine was set to 0.05mm / min, yielding a fracture toughness of 29.39MPa•m for the composite material. 1 / 2 .

[0111] Comparative Example 1

[0112] The same powder preparation process (i.e., step (1) in Example 1) and sintering process (i.e., the hot-pressing sintering process in step (4) of Example 1) were used as in Example 1, wherein 5 vol% Ti3AlC2 was added to the composite material. The difference from Example 1 is that in Comparative Example 1, the mixed powder was directly placed into a sintering mold, and a homogeneous Ti3AlC2-reinforced titanium-based composite material was prepared by hot-pressing sintering. Using the same performance testing method as in Example 1, the flexural strength of the composite material was measured to be 763 MPa, and the fracture toughness was 20.91 MPa·m. 1 / 2 .

[0113] Figure 1 and Figure 2 The images shown are scanning electron microscope (SEM) images of the cross-sections of the composite materials prepared in Examples 1 and 2, respectively. It can be seen that with the increase of the Ti3AlC2 content, the amount of TiC produced... x The higher the content, the more obvious its layered structure.

[0114] also, Figure 3 The XRD patterns of the composite materials prepared in Examples 1 and 2 are shown. It can be seen that with the increase of Ti3AlC2 content, the TiC content increases. x The more obvious the diffraction peaks, the better the TiC produced. x The content increased. Figure 4 The diagram shows a comparison of the quasi-static tensile properties of the composite materials prepared in Examples 1, 2, and 3. It can be seen that the tensile properties are optimal when the Ti3AlC2 content is 15 vol%, while the tensile properties are lowest when the Ti3AlC2 content is 20 vol%. This may be because with the increase of Ti3AlC2 content, the generated TiC... x Agglomeration occurs, resulting in coarse particles in the reinforcing phase, which affects its performance.

[0115] The addition amount of Ti3AlC2 in Example 1 accounts for 5.99 vol% of the entire layered composite material, and the bending strength and fracture toughness of the layered structure composite material prepared in Example 1 are higher than those of the homogeneous non-layered structure composite material prepared in Comparative Example 1, and the bending strength and fracture toughness are increased by more than 50%, and the design of the layered structure improves the performance of the composite material, and the improvement is high strength and high toughness.

[0116] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can also be made, which should be considered as the protection scope of the present application.

Claims

1. A high-strength and tough layered TiC structure x The method for preparing Ti-based composite materials is characterized by, Includes the following steps: Step S1: Prepare the substrate, wherein the substrate is a Ti-containing foil; Step S2, preparing a Ti-Ti3AlC2 composite sheet, which is prepared by an organic casting method from a powder slurry containing Ti and Ti3AlC2. Step S2 includes: Step S21: Weigh Ti3AlC2 powder and Ti powder and mix them to obtain a mixed powder, wherein the Ti powder has a particle size of 40-50 μm and the Ti3AlC2 powder has a particle size of 4-5 μm, and the addition ratio of Ti3AlC2 powder in the mixed powder is 5 vol%-20 vol% by volume. Step S22: Dissolve the adhesive in an organic solvent to obtain an organic solution containing the adhesive; Step S23: Add the mixed powder to the organic solution and disperse it to obtain a slurry; Step S24: The slurry is coated onto the substrate to form a coating layer on the substrate; Step S25: Dry the coating layer and demold it from the substrate surface to obtain the Ti-Ti3AlC2 composite sheet; Step S3: The Ti-Ti3AlC2 composite sheet and the substrate are alternately stacked in multiple layers to obtain a laminate; Step S4: The laminate is hot-pressed and sintered to obtain a high-strength and tough layered TiC structure. x / Ti-based composite materials, The Ti-Ti3AlC2 composite sheet is prepared by a casting method and has a thickness of 800-1500 μm.

2. The preparation method according to claim 1, characterized in that, The Ti-containing foil is made of any one of pure Ti, TC4 titanium alloy, or TA15 titanium alloy, and has a thickness of 30-100μm.

3. According to the preparation method of claim 1, in step S21, the mixture is mixed by ball milling, wherein the ball-to-material ratio in the ball milling is (2-5):1, and the ball milling is carried out at a speed of 100-150 r / min for 20-25 h.

4. The preparation method according to claim 1, characterized in that, Step S22 includes: The adhesive is dispersed and dissolved in anhydrous ethanol solvent and stirred until completely dissolved; The plasticizer is added and the mixture is stirred until completely dissolved to obtain the organic solution.

5. The preparation method according to claim 4, wherein, The binder is polyvinyl butyral (PVB), and the plasticizer is dibutyl phthalate (DBP) or dioctyl phthalate (DOP). The binder content in anhydrous ethanol is 4.5 wt.%-5.5 wt.%, and the amount of plasticizer added relative to the binder is (1-1.5):

1.

6. The preparation method according to claim 1, characterized in that, In step S23, the content of the mixed powder in the slurry is 40 wt.%-60 wt.%, and step S23 includes: The mixed powder is added to the organic solution, first ultrasonically dispersed, then mechanically stirred to obtain a uniformly dispersed slurry.

7. The preparation method according to claim 1, characterized in that, Step S4 includes: Step S41: Pre-compress the laminate under an axial mechanical pressure of 2-10 MPa and maintain the pressure for a predetermined time; Step S42: The pre-compressed laminate is hot-pressed and sintered at 1200-1400℃ and 20-50MPa for 1-3 hours to obtain a high-strength and tough layered TiC structure. x / Ti-based composite materials.

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