Layered gradient ti-ti based composite material, method of making and use thereof

Abstract

The application belongs to the technical field of powder metallurgy composite materials, and particularly relates to a layered gradient Ti-Ti-based composite material and a preparation method and application thereof. The material comprises a base layer and a composite reinforcing layer, and the volume ratio of the base layer to the composite reinforcing layer is (6-10):1; the base layer is a titanium or titanium alloy layer; the composition of the composite reinforcing layer comprises a base titanium, an intermediate alloy B and a particle reinforcing body C, wherein the intermediate alloy B is selected from one or more of Al-V alloy, Al-Mo alloy and Al-Sn alloy; and the particle reinforcing body C is selected from one or more of TiB2, B4C, SiC and Al2O3. By adding the particle reinforcing body, the wear resistance of the titanium-based composite material is effectively improved, so that the obtained material has excellent wear resistance and is widely used. Through a two-stage compression molding process, the particle reinforcing body titanium-based composite material is combined with titanium or titanium alloy, and the manufacturing process is simple, and industrial production can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of powder metallurgy composite materials, and particularly relates to a layered gradient Ti-Ti-based composite material and a preparation method and application thereof. BACKGROUND

[0002] Titanium is an important structural metal developed in the 1950s, has the characteristics of high strength, low density, good corrosion resistance and good heat resistance, and is widely used in various fields. The main preparation method of titanium-based composite material is to use a mixture of metal and metal powder (or metal and non-metal powder) as raw material, through the processes of pressure forming and sintering, to manufacture metal materials, composite materials and various types of products.

[0003] In recent years, with the implementation of domestic aviation, aerospace, military and other national major projects, higher technical requirements have been put forward for the application of titanium, titanium alloy and titanium-based composite materials in high-end fields. The materials manufactured by conventional processes of traditional titanium and titanium alloy have poor wear resistance, which cannot meet the material requirements of track plates and other parts. The track plate is one of the main components of the running system of tanks, armored vehicles and the like, and its main performance is to reduce the movement resistance of the vehicle to ensure the normal operation of the vehicle on the off-road surface. Due to the particularity of its working environment, the material as a whole requires lightweight and high strength, and the lower ground surface position needs to have high strength, high hardness and high wear resistance. SUMMARY

[0004] In view of the problems existing in the prior art, the application provides a layered gradient Ti-Ti-based composite material and a preparation method and application thereof, which combines titanium and titanium alloy with ceramic reinforced titanium-based composite material, wherein the ceramic reinforced titanium-based composite material serves as a composite reinforcing layer and has good wear resistance; titanium and titanium alloy serve as a base layer and meet the overall lightweight and high strength of the material. The material as a whole has the characteristics of lightweight, high strength, high hardness and high wear resistance, and can be widely applied in the fields of aviation, aerospace, ships, weapons, biological medicine and the like. The application specifically includes the following contents:

[0005] A layered gradient Ti-Ti-based composite material, comprising a base layer and a composite reinforcing layer, the volume ratio of the base layer and the composite reinforcing layer is (6-10): 1; the base layer is a titanium or titanium alloy layer;

[0006] The composition of the composite reinforcing layer comprises: a base titanium, an intermediate alloy B and a particle reinforcement C, wherein:

[0007] The intermediate alloy B is selected from one or more of Al-V alloy, Al-Mo alloy and Al-Sn alloy;

[0008] The particle reinforcement C is selected from one or more of TiB2, B4C, SiC, Al2O3.

[0009] Preferably, the weight percentage of each component in the composite reinforcement layer is: base titanium 72-84%, intermediate alloy B 0-12%, and particle reinforcement C 4-16%.

[0010] Preferably, the weight percentage of each component in the composite reinforcement layer is: base titanium 75-80%, intermediate alloy B 5-10%, and particle reinforcement C 8-12%.

[0011] A preparation method of a layered gradient Ti-Ti-based composite material, comprising the following steps:

[0012] (1) batching: proportionally batching raw material powders of base titanium, intermediate alloy B, and particle reinforcement C, and then mixing and ball milling to obtain composite reinforcement material powder;

[0013] (2) compression molding: compression molding the titanium powder or titanium alloy powder and the composite reinforcement material powder in proportion to obtain a green body;

[0014] (3) hot-pressing sintering: hot-pressing sintering the green body in a vacuum environment to obtain a sintered body;

[0015] (4) heat treatment: heat treating the sintered body to obtain a layered gradient Ti-Ti-based composite material.

[0016] Preferably, the ball milling method of step (1) is as follows: first, the prepared raw material powders are added to a high-energy ball mill, then grinding balls are put in according to a ball-to-material ratio of (0.8-1.2):1, nitrogen is introduced, and then ball milling is started; the grinding balls include equal amounts of grinding balls with diameters of 8-12 mm and grinding balls with diameters of 3-5 mm; the rotation speed of the high-energy ball mill is set to 250-300 r / min, and the ball milling time is 3-3.5 h. Using the ball milling parameters defined in the application, the powders can be ground to the optimal particle size range (50-100 microns), achieving the best alloying and bonding effects.

[0017] Preferably, the compression molding method of step (2) is as follows: first, the composite reinforcement material powder is laid on the lower die plate of a mold, and the composite reinforcement material powder on the lower die plate is compression molded using an upper die plate with the same shape as the lower die plate at a pressure of 0.5-0.8 MPa; then, the upper die plate is removed, and the titanium powder or titanium alloy powder is laid on the compression molded composite reinforcement material, and then compression molded using the upper die plate at a pressure of 8-10 MPa to obtain a green body.

[0018] Preferably, the hot rolling sintering method of step (3) is as follows: the green body is placed in a vacuum hot pressing sintering furnace, the furnace is vacuumized, when the vacuum degree reaches 10 Pa or less, heating is started, first, the temperature is raised to 500-600 DEG C at a temperature rising rate of 15-20 DEG C / min, and the temperature is kept for 0.5-1 h; protective gas is introduced until the pressure in the furnace reaches 0.03-0.05 MPa; then the temperature is raised to 1000-1200 DEG C at a rate of 10-15 DEG C / min; then the pressure is increased to 25-30 MPa, and the temperature and pressure are kept for 3-4 h; finally, the furnace is cooled to obtain a sintered body.

[0019] Preferably, the heat treatment method of step (4) is as follows: the sintered body is placed in a heat treatment furnace, the temperature is raised to 900-1000 DEG C at a rate of 8-18 DEG C / min and kept for 3-5 h; then the temperature is lowered to 450-550 DEG C at a rate of 5-10 DEG C / min; finally, the furnace is cooled to obtain a layered gradient Ti-Ti-based composite material.

[0020] A track shoe or an armor plate prepared from the layered gradient Ti-Ti-based composite material.

[0021] Application of the layered gradient Ti-Ti-based composite material in aviation equipment, space equipment, ships, weapons or medical devices.

[0022] Advantages of the present application:

[0023] (1) The layered gradient Ti-Ti-based composite material disclosed by the present application comprises a substrate layer and a composite reinforcing layer, wherein the composite reinforcing layer is the most important functional layer, the wear resistance of the titanium-based composite material is effectively improved by adding a particle reinforcing body, the material has the characteristics of high hardness and high wear resistance, the obtained material ground surface part has excellent wear resistance, and the material has wide application. The titanium or titanium alloy substrate layer is the main structural layer and plays an important strength characteristic. The content of the reinforcing body powder added in the composite reinforcing layer in the present application is low, so there is no obvious interface effect between the composite reinforcing layer and the titanium or titanium alloy substrate layer, and the interface bonding strength between the two layers can be effectively improved. In the material use process, the composite reinforcing layer is not easy to fall off, the service life is long, and at the same time, surface plating treatment or inlaying stainless steel is not needed, and the product manufacturing process is simple. The present application realizes a high-quality, multi-component powder metallurgy process, and the obtained material ground surface has excellent wear resistance, which is an excellent alternative scheme of a steel track shoe.

[0024] (2) The preparation method of the layered gradient Ti-Ti-based composite material disclosed in the present application first ball-mills the raw material powder. The high-energy ball mill breaks the powder to the size of nanometer through the high-speed ball-milling mixing process. Since the size of the powder is reduced, the surface area is increased, the surface energy is improved, and thus the surface activity of the powder is greatly improved, and the bonding strength between the powders is increased. At the same time, the heat generated by the ball-milling collision can provide the energy required for the mutual reaction between the powders, and thus the alloying reaction between the powders is generated. The high-energy ball-milling can ensure the interface bonding effect between the reinforcing material and the matrix in the composite material, and thus the comprehensive quality of the material described in the present application is excellent.

[0025] (3) The forming process involved in the preparation method of the layered gradient Ti-Ti-based composite material disclosed in the present application includes a two-stage pressing process. First, the composite reinforcing material powder is uniformly laid on the lower die plate of the mold, and the upper die plate with the same shape as the lower die plate is used to press form at a pressure of 0.5-0.8 MPa. In this process, a smaller pressure is applied to make the composite reinforcing material powder completely fill the mold and have uniform thickness, while ensuring that the material has a lower density. Then, the upper die plate is removed, the titanium or titanium alloy powder is laid, and the upper die plate of the mold is used to press form at a pressure of 8-10 MPa to obtain a layered gradient Ti-Ti-based composite material green body. After filling the second layer of powder, a larger pressure is applied to make the material have a larger density, and at the same time, the bonding strength between the interface of the first layer of powder and the second layer of powder is improved, ensuring that the titanium or titanium alloy in the layered Ti-Ti-based composite material and the particle reinforced titanium matrix composite material are in a firm and close metallurgical bonding state.

[0026] (4) In the preparation method of the layered gradient Ti-Ti-based composite material disclosed in the present application, sintering body heat treatment is an important processing step. In this scheme, the material property is a layered gradient composite material. Although the composition is relatively similar, the interface bonding strength is guaranteed to a certain extent, however, the interface mismatch caused by the different compositions still exists. Therefore, through the heat treatment process, the interlayer thermal mismatch stress can be effectively reduced, the overall stress level of the material can be effectively reduced, and the stability of the material can be ensured. DETAILED DESCRIPTION

[0027] The present application will be described in detail below with specific embodiments. The embodiments shown below do not limit the invention described in the claims in any way. In addition, the entire content of the constitution represented by the following embodiments is not limited to what is necessary as a solution to the invention described in the claims.

[0028] A layered gradient Ti-Ti based composite material, comprising a substrate layer and a composite reinforcement layer, the volume ratio of the substrate layer and the composite reinforcement layer being (6-10):1; the substrate layer is a titanium or titanium alloy layer; the composition of the composite reinforcement layer comprises (mass percentage): base titanium 72-84% (for example 75%, 77%, 79%, 80%, 82%, 83%, etc.), intermediate alloy B 0-12% (for example 0, 1%, 2%, 4%, 6%, 8%, 10%, etc.), and particulate reinforcement C 4-16% (for example 4.5%, 5%, 6%, 8%, 10%, 12%, 14%, etc.), the intermediate alloy B being selected from one or more of Al-V alloy, Al-Mo alloy, Al-Sn alloy; the particulate reinforcement C being selected from one or more of TiB2, B4C, SiC, Al2O3. The layered gradient Ti-Ti based composite material of the present application can be used to prepare track shoes or armor plates. The layered gradient Ti-Ti based composite material of the present application can be applied in various fields such as aviation equipment, aerospace equipment, ships, weapons or medical devices, etc.

[0029] A method for preparing a layered gradient Ti-Ti based composite material, comprising the following steps:

[0030] (1) batching: proportionally prepare raw material powders of base titanium, intermediate alloy B and particulate reinforcement C, first add the prepared raw material powders into a high-energy ball mill, then put in grinding balls according to a ball-to-powder ratio of (0.8-1.2):1 (for example 0.9:1, 1:1, 1.1:1, etc.), introduce nitrogen, and then start ball milling; the grinding balls comprise equal amounts of grinding balls with a diameter of 8-12 mm (for example 9 mm, 10 mm, 11 mm, etc.) and grinding balls with a diameter of 3-5 mm (for example 3.5 mm, 4 mm, 4.5 mm, etc.); the rotation speed of the high-energy ball mill is set to 250-300 r / min (for example 260 r / min, 270 r / min, 280 r / min, 290 r / min, etc.), and the ball milling time is 3-3.5 h (for example 3.1 h, 3.2 h, 3.3 h, 3.4 h, 3.5 h, etc.);

[0031] (2) compression molding: first, lay the composite reinforcement material powder on the lower mold plate of the mold, and use the upper mold plate with the same shape as the lower mold plate to press the composite reinforcement material powder on the lower mold plate at a pressure of 0.5-0.8 MPa (for example 0.55 MPa, 0.6 MPa, 0.65 MPa, 0.7 MPa, 0.75 MPa, etc.) to form a green body; then, remove the upper mold plate, lay titanium powder or titanium alloy powder on the formed green body, and then use the upper mold plate to press at a pressure of 8-10 MPa (for example 8.5 MPa, 9 MPa, 9.5 MPa, 9.8 MPa, etc.) to form a green body;

[0032] (3) Hot-pressing sintering: the green body is placed in a vacuum hot-pressing sintering furnace, the furnace is vacuumized, when the vacuum degree reaches 10 Pa or less (for example, 9 Pa, 8 Pa, 5 Pa, 2 Pa, 1 Pa, etc.), heating is started, first, the temperature is raised to 500-600°C (for example, 520°C, 540°C, 560°C, 580°C, etc.) at a temperature raising rate of 15-20°C / min (for example, 16°C / min, 17°C / min, 18°C / min, 19°C / min, etc.), and the temperature is kept for 0.5-1h (for example, 0.6h, 0.7h, 0.8h, 0.9h, etc.); protective gas is introduced until the pressure in the furnace reaches 0.03-0.05MPa (for example, 0.035MPa, 0.04MPa, 0.045MPa, etc.); then the temperature is raised to 1000-1200°C (for example, 1020°C, 1050°C, 1100°C, 1150°C, etc.) at a rate of 10-15°C / min (for example, 11°C / min, 12°C / min, 13°C / min, 14°C / min, etc.); then the pressure is increased to 25-30MPa (for example, 26MPa, 27MPa, 28MPa, 29MPa, etc.), and the temperature is kept for 3-4h (for example, 3.2h, 3.4h, 3.6h, 3.8h, etc.); finally, the furnace is cooled to room temperature, and a sintered body is obtained;

[0033] (4) Heat treatment: the sintered body is placed in a heat treatment furnace, the temperature is raised to 900-1000°C (for example, 920°C, 940°C, 960°C, 980°C, etc.) at a rate of 8-18°C / min (for example, 10°C / min, 12°C / min, 14°C / min, 16°C / min, etc.), and the temperature is kept for 3-5h (for example, 3.2h, 3.5h, 4.0h, 4.2h, 4.5h, 4.8h, etc.); then the temperature is lowered to 450-550°C (for example, 460°C, 480°C, 500°C, 520°C, etc.) at a rate of 5-10°C / min (for example, 6°C / min, 7°C / min, 8°C / min, 9°C / min, etc.); finally, the furnace is cooled to room temperature, and a layered gradient Ti-Ti-based composite material is obtained.

[0034] Example 1

[0035] A layered gradient Ti-Ti-based composite material, comprising: a first layer being a particle reinforced titanium-based composite material (i.e., a composite reinforced layer, the same below), and a second layer being titanium or titanium alloy (i.e., a substrate layer, the same below), the volume ratio of the first layer to the second layer being 1:8.

[0036] A method for preparing a layered gradient Ti-Ti-based composite material, comprising the following steps:

[0037] Step 1: First layer of particle reinforced titanium matrix composite ingredient design: the titanium matrix composite ingredient includes matrix titanium A, intermediate alloy B and particle reinforcement C. Among them: the intermediate alloy B is selected from Al-V alloy, and the particle reinforcement C is selected from B4C as raw material. The weight percentage of the first layer of particle reinforced titanium matrix composite ingredient is: matrix titanium A: 83.3%, intermediate alloy B: 10.5%, and particle reinforcement C: 6.2%.

[0038] Step 2: First layer of high-energy ball milling of powder: according to the mass percentage described in step (1), the raw materials of the first layer of powder, including matrix titanium, intermediate alloy and particle reinforcement, are added to a high-energy ball mill in proportion, and ZrO2 grinding balls with a diameter of 10 mm and an equal amount of ZrO2 grinding balls with a diameter of 4 mm are added, with a ball-to-material ratio of 1:1. N2 is introduced, and the ball milling is started. Among them, the rotation speed of the ball mill is 250 r / min, and the ball milling time is 3.5 h. The first layer of particle reinforced titanium matrix composite powder is obtained by ball milling and mixing.

[0039] Step 3: Molding: the first layer of particle reinforced titanium matrix composite powder is uniformly laid on the lower mold plate of the mold, and the upper mold plate with the same shape as the lower mold plate is used to press form at a pressure of 0.6 MPa; the upper mold plate is removed, the second layer of titanium or titanium alloy powder is laid, and the mold upper mold plate is used to press form at a pressure of 10 MPa, obtaining a layered gradient Ti-Ti matrix composite green body.

[0040] Step 4: Hot pressing sintering: the prepared green body is placed in a vacuum hot pressing sintering furnace, the vacuum pump is opened, and the air in the furnace is pumped out to form a vacuum environment. When the vacuum degree reaches below 10 Pa, heating is started. First, the temperature is raised from room temperature to 500℃ at a rate of 18℃ / min, and the temperature is kept for 0.8h. Protective gas argon is introduced until the pressure in the furnace reaches 0.04 MPa. The temperature is raised to 1100℃ again at a rate of 15℃ / min. The press is started and slowly pressurized to 25 MPa, and the temperature is kept for 4h. The furnace is cooled to room temperature, and a layered gradient Ti-Ti matrix composite sintered body is obtained.

[0041] Step 5: Heat treatment of sintered body: the layered gradient Ti-Ti matrix composite sintered body obtained in step (4) is placed in a heat treatment furnace, the temperature is raised to 1000℃ at a rate of 15℃ / min and kept for 4h, then the temperature is lowered to 500℃ at a rate of 5℃ / min, and then the furnace is cooled to room temperature. A layered gradient Ti-Ti matrix composite is obtained.

[0042] Example 2

[0043] A layered gradient Ti-Ti matrix composite, comprising: a first layer of particle reinforced titanium matrix composite, and a second layer of titanium or titanium alloy, the volume ratio of the first layer to the second layer being 1:9.

[0044] A method for preparing a layered gradient Ti-Ti based composite material, comprising the following steps:

[0045] Step 1: First layer of particle reinforced titanium matrix composite component design: the titanium matrix composite component comprises a matrix titanium A and a particle reinforcement C. The particle reinforcement C is selected from TiB2 as raw material. The weight percentage of the first layer of particle reinforced titanium matrix composite component is: matrix titanium A: 84%, particle reinforcement C: 16%.

[0046] Step 2: First layer of high-energy ball milling: according to the mass percentage described in step (1), the raw materials of the first layer of powder, including the matrix titanium, the intermediate alloy and the particle reinforcement, are added to the high-energy ball mill in proportion, and the same amount of ZrO2 grinding balls with a diameter of 10 mm and a diameter of 4 mm are added, the ball-to-material ratio is 1:1, N2 is introduced, and the ball milling is started. Among them, the rotation speed of the ball mill is 300 r / min, and the ball milling time is 3.2 h. The first layer of particle reinforced titanium matrix composite powder is obtained by ball milling and mixing.

[0047] Step 3: Molding: the first layer of particle reinforced titanium matrix composite powder is uniformly laid on the lower mold plate of the mold, and the upper mold plate with the same shape as the lower mold plate is used to press form at a pressure of 0.5 MPa; the upper mold plate is removed, the second layer of titanium or titanium alloy powder is laid, and the mold upper mold plate is used to press form at a pressure of 9 MPa, to obtain a layered gradient Ti-Ti based composite green body.

[0048] Step 4: Hot pressing sintering: place the prepared green body in a vacuum hot pressing sintering furnace, open the vacuum pump, and exhaust the air in the furnace to form a vacuum environment. When the vacuum degree reaches below 10 Pa, start heating, first increase the temperature from room temperature to 550℃ at a rate of 15℃ / min, and keep the temperature for 0.8h; introduce protective gas argon until the pressure in the furnace is 0.05 MPa, and then increase the temperature to 1150℃ at a rate of 15℃ / min; start the press to slowly pressurize to 26 MPa, and keep the temperature and pressure for 3.8h; cool down to room temperature with the furnace, to obtain a layered gradient Ti-Ti based composite sintered body.

[0049] Step 5: Sintered body heat treatment: place the layered gradient Ti-Ti based composite sintered body obtained in step (4) in a heat treatment furnace, heat to 980℃ at a rate of 12℃ / min and keep the temperature for 4h, then cool to 500℃ at a rate of 7℃ / min, and then cool to room temperature with the furnace, to obtain a layered gradient Ti-Ti based composite material.

[0050] Example 3

[0051] A layered gradient Ti-Ti based composite material, comprising: a first layer of particle reinforced titanium matrix composite material, and a second layer of titanium or titanium alloy, the volume ratio of the first layer to the second layer being 1:6.

[0052] A preparation method of a layered gradient Ti-Ti based composite material, comprising the following steps:

[0053] Step 1: First layer particle reinforced titanium matrix composite component design: the titanium matrix composite component comprises a base titanium A, an intermediate alloy B and a particle reinforcement C. Among them: the intermediate alloy B is selected from Al-Mo alloy and Al-Sn alloy, and the particle reinforcement C is selected from TiB2 as raw materials. The weight percentage of the first layer particle reinforced titanium matrix composite component is: base titanium A: 72.8%, intermediate alloy B: Al-Mo alloy 2.4%, Al-Sn alloy 9.6%, particle reinforcement C: 15.2%.

[0054] Step 2: First layer high-energy ball milling: according to the mass percentage described in step (1), the raw materials of the first layer powder, the base titanium, the intermediate alloy and the particle reinforcement, are added to the high-energy ball mill in proportion, and the same amount of ZrO2 grinding balls with a diameter of 10 mm and a diameter of 4 mm are added, the ball-to-material ratio is 1:1, N2 is introduced, and the ball milling is started. Among them, the rotating speed of the ball mill is 260r / min, and the ball milling time is 3.5h. The first layer particle reinforced titanium matrix composite powder is obtained by ball milling and mixing.

[0055] Step 3: Molding: the first layer particle reinforced titanium matrix composite powder is uniformly laid on the lower mold plate of the mold, and the upper mold plate with the same shape as the lower mold plate is used to press form at a pressure of 0.5MPa; the upper mold plate is taken out, the second layer titanium or titanium alloy powder is laid, and the mold upper mold plate is used to press form at a pressure of 8MPa, to obtain a layered gradient Ti-Ti based composite material green body.

[0056] Step 4: Hot pressing sintering: place the prepared green body in a vacuum hot pressing sintering furnace, open the vacuum pump, and exhaust the air in the furnace to form a vacuum environment. When the vacuum degree reaches below 10Pa, start heating, first increase the temperature from room temperature to 600℃ at a rate of 15℃ / min, and keep the temperature for 0.5h; introduce protective gas argon until the pressure in the furnace is 0.05MPa, and then increase the temperature to 1000℃ at a rate of 10℃ / min; start the press to slowly pressurize to 28MPa, and keep the temperature and pressure for 3h; cool down to room temperature with the furnace, to obtain a layered gradient Ti-Ti based composite material sintered body.

[0057] Step 5: Heat treatment of sintered body: place the layered gradient Ti-Ti based composite material sintered body obtained in step (4) in a heat treatment furnace, heat to 950℃ at a rate of 18℃ / min and keep the temperature for 4h, then cool to 500℃ at a rate of 8℃ / min, and then cool to room temperature with the furnace, to obtain a layered gradient Ti-Ti based composite material.

[0058] Example 4

[0059] A layered gradient Ti-Ti based composite material, comprising: a first layer being a particle reinforced titanium matrix composite material, and a second layer being titanium or titanium alloy, the volume ratio of the first layer to the second layer being 1:10.

[0060] A method for preparing a layered gradient Ti-Ti based composite material, comprising the following steps:

[0061] Step 1: component design of the first layer particle reinforced titanium matrix composite material: the titanium matrix composite material component comprises a base titanium A, an intermediate alloy B and a particle reinforcement C. The intermediate alloy B is selected from Al-V alloy and Al-Mo alloy, and the particle reinforcement C is selected from SiC as raw material. The weight percentage of the component of the first layer particle reinforced titanium matrix composite material is: base titanium A: 83.8%, intermediate alloy B: Al-V alloy 5%, Al-Mo alloy 5%, and particle reinforcement C: 6.2%.

[0062] Step 2: high-energy ball milling of the first layer powder: according to the mass percentage described in step (1), the raw materials of the first layer powder, i.e. the base titanium, the intermediate alloy and the particle reinforcement, are added into a high-energy ball mill in proportion, and an equal amount of ZrO2 grinding balls with a diameter of 10 mm and 4 mm are added, the ball-to-material ratio is 1:1, N2 is introduced, and the ball milling is started. The rotation speed of the ball mill is 280 r / min, and the ball milling time is 3.3 h. The first layer particle reinforced titanium matrix composite material powder is obtained after ball milling and mixing.

[0063] Step 3: mold pressing: the first layer particle reinforced titanium matrix composite material powder is uniformly laid on the lower mold plate of the mold, and the upper mold plate with the same shape as the lower mold plate is used to press form at a pressure of 0.8 MPa; the upper mold plate is removed, the second layer titanium or titanium alloy powder is laid, and the mold upper mold plate is used to press form at a pressure of 9 MPa, to obtain a layered gradient Ti-Ti based composite material green body.

[0064] Step 4: hot pressing sintering: the prepared green body is placed in a vacuum hot pressing sintering furnace, the vacuum pump is opened, the air in the furnace is pumped out to form a vacuum environment, when the vacuum degree reaches below 10 Pa, heating is started, first the temperature is raised from room temperature to 550℃ at a rate of 20℃ / min, and the temperature is kept for 1 h; protective gas argon is introduced until the pressure in the furnace is 0.03 MPa, and the temperature is raised to 1200℃ again at a rate of 12℃ / min; the press is started to slowly pressurize to 30 MPa, and the temperature is kept for 3.5 h; the furnace is cooled to room temperature, and a layered gradient Ti-Ti based composite material sintered body is obtained.

[0065] Step 5: heat treatment of the sintered body: the layered gradient Ti-Ti based composite material sintered body obtained in step 4 is placed in a heat treatment furnace, the temperature is raised to 900℃ at a rate of 8℃ / min and kept for 4 h, then the temperature is lowered to 500℃ at a rate of 10℃ / min, and then the furnace is cooled to room temperature, to obtain a layered gradient Ti-Ti based composite material.

[0066] Comparative Example 1

[0067] Comparative Example 1 is different from Example 1 in that the first layer of particle reinforced titanium matrix composite composition design. The powders of the composite in this comparative example are selected from titanium or titanium alloy, wherein the titanium alloy is selected from Ti-6Al-4V, and the rest of the parameters of the powder compaction molding, sintering and sintered body heat treatment are the same as those of Example 1.

[0068] Comparative Example 2

[0069] Comparative Example 2 is different from Example 1 in that the first layer of powder is high-energy ball milled. The powder weighed in step 2 is added to the high-energy ball mill jar, and ZrO2 grinding balls with a diameter of 10 mm and an equal amount of ZrO2 grinding balls with a diameter of 4 mm are added to the ball mill jar, and the ball-to-material ratio is 1:1. After the powder is loaded, N2 is introduced. Start ball milling, wherein the rotation speed of the ball mill is 200 r / min, and the ball milling time is 3 h to obtain the first layer of powder. The rest is the same as Example 1.

[0070] Comparative Example 3

[0071] Comparative Example 3 is different from Example 1 in that the powder is compacted. The first layer of particle reinforced titanium matrix composite powder and the second layer of titanium or titanium alloy powder are uniformly laid in the mold according to the volume ratio, wherein the first layer of powder is laid on the ground surface part at the bottom, and the pressure is compacted to form a layered gradient Ti-Ti matrix composite green body at a pressure of 9 MPa. The rest is the same as Example 1.

[0072] Table 1 shows the comprehensive comparison of the mechanical properties, density and other properties of the layered gradient Ti-Ti matrix composites prepared in Examples 1-4 and Comparative Examples 1-3 of the present application.

[0073] Table 1 Mechanical properties, density and other performance parameters of layered gradient Ti-Ti matrix composites

[0074]

[0075] As can be seen from Table 1, the hardness and strength of the Ti-Ti based composite material obtained in Examples 1-4 are both high, which shows that the component design of the alloy, the high-energy ball milling, the hot-pressing sintering and the heat treatment process of the sintered body are reasonable, and the technical scheme is feasible. Compared with Example 1, the powders of the composite material in Comparative Example 1 are selected from titanium or titanium alloy, and the strength and hardness are very low because no particle reinforcement is added, which cannot meet the use requirements of related materials. Compared with Example 1, in Comparative Example 2, the high-energy ball milling step of the first layer powder, because of the low-speed ball milling treatment, the powder size is large, the surface area is reduced, the surface energy is reduced, the surface activity of the powder is reduced, the bonding strength between the powders is not enough, which leads to the density, strength and hardness of the material being greatly affected. Compared with Example 1, in Comparative Example 3, the step of die forming, because the low-pressure forming process of the first layer of particle reinforced titanium-based composite material powder is cancelled, the first layer of powder and the second layer of powder are uniformly laid in the mold according to the volume ratio, and the one-time high-pressure forming is carried out, which may cause the lower mold recess to be not filled or the density to be low, which leads to the strength and hardness of the material being significantly reduced.

[0076] The above description of disclosed embodiments enables one skilled in the art to make or use the application. Numerous modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a layered gradient Ti-Ti based composite material, characterized in that, Includes the following steps: (1) Batching: Prepare raw material powders of matrix titanium, intermediate alloy B and particulate reinforcement C according to the following proportions: matrix titanium 72-84%, intermediate alloy B 0-12%, and particulate reinforcement C 4-16% by weight. Then, add the prepared raw material powders into a high-energy ball mill, and add grinding balls at a ball-to-material ratio of (0.8-1.2):

1. Introduce nitrogen gas and start ball milling. The grinding balls include equal amounts of grinding balls with a diameter of 8-12 mm and grinding balls with a diameter of 3-5 mm. The rotation speed of the high-energy ball mill is set to 250-300 r / min, and the ball milling time is 3-3.5 h to obtain composite reinforced material powder. The intermediate alloy B is selected from one or more of Al-V alloy, Al-Mo alloy, and Al-Sn alloy. The particulate reinforcement C is selected from one or more of TiB2, B4C, SiC, and Al2O3. (2) Compression molding: The composite reinforcing material powder is laid on the lower mold plate, and the composite reinforcing material powder on the lower mold plate is pressed into shape using an upper mold plate with the same shape as the lower mold plate at a pressure of 0.5-0.8MPa; then, the upper mold plate is removed, and titanium powder or titanium alloy powder is laid on the pressed composite reinforcing material. The ratio of titanium powder or titanium alloy powder to composite reinforcing material powder by volume is (6-10):

1. Then, the upper mold plate is used to press into shape at a pressure of 8-10MPa to obtain a green blank; (3) Hot pressing sintering: The green blank is placed in a vacuum hot pressing sintering furnace. The furnace is evacuated. When the vacuum degree reaches below 10 Pa, heating is started. The temperature is first raised to 500-600℃ at a rate of 15-20℃ / min and held for 0.5-1h. Protective gas is introduced until the pressure inside the furnace reaches 0.03-0.05MPa. The temperature is then raised to 1000-1200℃ at a rate of 10-15℃ / min. The pressure is then increased to 25-30MPa and held for 3-4h. Finally, the furnace is cooled to obtain the sintered body. (4) Heat treatment: The sintered body is placed in a heat treatment furnace and heated to 900-1000℃ at a rate of 8-18℃ / min and held for 3-5h; then cooled to 450-550℃ at a rate of 5-10℃ / min; finally cooled with the furnace to obtain a layered gradient Ti-Ti based composite material.

2. The method for preparing a layered gradient Ti-Ti based composite material according to claim 1, characterized in that, The weight percentages of each component in the composite reinforcement layer are as follows: 75-80% titanium matrix, 5-10% intermediate alloy B, and 8-12% particulate reinforcement C.

3. A layered gradient Ti-Ti based composite material prepared by the method according to any one of claims 1-2, characterized in that, It includes a base layer and a composite reinforcement layer, wherein the volume ratio of the base layer to the composite reinforcement layer is (6-10):1; the base layer is a titanium or titanium alloy layer; the composite reinforcement layer comprises: a titanium matrix, an intermediate alloy B, and a particulate reinforcement C.

4. A track plate or armor plate made using the layered gradient Ti-Ti based composite material as described in claim 3.

5. The application of the layered gradient Ti-Ti based composite material according to claim 3 in aerospace equipment, shipbuilding equipment, weaponry or medical devices.

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