A carbon dot-reinforced titanium matrix composite material based on discharge plasma sintering and its preparation method

Abstract

This invention discloses a carbon dot-reinforced titanium-based composite material based on spark plasma sintering and its preparation method, belonging to the field of metal matrix composite material preparation technology. The method includes step S1: preparing biomass carbon dots; step S2: mixing the obtained biomass carbon dots and TC4 powder for batching, wherein the amount of biomass carbon dots added accounts for 0-2.35% of the total weight of the raw material powder; step S3: after uniform mixing of the batched raw materials, ball milling and drying are performed; step S4: the treated raw material powder is sintered by spark plasma sintering, and then cooled to room temperature to obtain the titanium-based composite material. This invention utilizes carbon dots combined with SPS technology to synthesize a TiCp reinforcing phase in situ with fine grain size and high interfacial bonding strength with the matrix, significantly improving the mechanical properties of the titanium matrix. The resulting product exhibits a density of over 99.5%, compressive strength of 1724 MPa-1803 MPa, yield strength of 1056-1176 MPa, hardness of 333 HV-405 HV, and engineering strain of over 28.36%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal matrix composite material, and particularly relates to a carbon dot reinforced titanium matrix composite material based on discharge plasma sintering and a preparation method thereof. BACKGROUND

[0002] Titanium matrix composite materials have high specific stiffness and specific strength, excellent wear resistance and oxidation resistance, and thus have become the focus of research in the field of materials in recent years and have great application in the fields of aerospace, military manufacturing, automobiles and ships, and biological medicine. Titanium matrix composite materials can be divided into continuous fiber reinforced titanium matrix composite materials and discontinuous reinforced titanium matrix composite materials according to the reinforcing phase. Due to the complicated preparation process, high cost, and complex interface reaction of continuous fiber reinforced titanium matrix composite materials, the research direction in recent years is mainly discontinuous reinforced titanium matrix composite materials.

[0003] The in-situ synthesized reinforcing phase has no complex interface reaction with the matrix, high interface bonding capacity, and high thermodynamic stability. TiC particles have a high melting point, high elastic modulus, good wear resistance, similar density and Poisson ratio to titanium alloy, and similar thermal expansion coefficient to titanium alloy, and have good chemical stability in the matrix material, no complex interface reaction, high interface bonding strength, and become one of the best reinforcing phase options. Currently, the TiC reinforcing phase synthesized by general carbon sources has a grain size that coarsens and agglomerates with the increase of the content, and is prone to form dendritic morphology, thereby reducing the mechanical properties of the titanium matrix composite material reinforced by the reinforcing phase.

[0004] According to the search, the Chinese patent application No. 201110351956.2, filed on November 9, 2011, has an invention name of a method for preparing carbon nanotube reinforced titanium matrix composite material by in-situ reaction. The method of the application is as follows: nickel nitrate hexahydrate and TiH2 powder are added to an ethanol solution and stirred, evaporated to obtain Ni-TiH2 composite powder; the powder is placed in a quartz boat and put into a deposition device, H2 is introduced, then the temperature is raised, CH4 gas is introduced, after the deposition is completed, the introduction of CH4 gas is stopped, and carbon nanotube / TiH2 composite powder is obtained; the powder is pressed into a block, sintered, and re-pressed to obtain carbon nanotube reinforced titanium matrix composite material. The application uses TiH2 powder as the form of titanium addition, and prepares carbon nanotubes at low temperature, effectively avoiding the reaction between titanium and carbon in the matrix, ensuring that the matrix material is not damaged, solving the problem of easy agglomeration and difficult dispersion of carbon nanotubes in the composite material, and improving the mechanical properties and high temperature resistance of the composite material. However, due to the high difficulty of the process, the yield of the prepared carbon nanotubes is low, and the process cannot be applied on a large scale. In addition, the interface bonding capacity of the prepared titanium matrix composite material is weak, and the mechanical properties are not excellent. SUMMARY

[0005] 1. Problem to be solved

[0006] The purpose of the present application is to overcome the problem that the TiC particle reinforced phase with large grain size synthesized by traditional method using ordinary carbon source is easy to form dendritic morphology, thereby reducing the mechanical properties of titanium-based composite material. The present application provides a carbon dot reinforced titanium-based composite material based on spark plasma sintering and a preparation method thereof. The technical scheme of the present application can effectively solve the above problems and prepare a dense titanium-based composite material with a density of more than 99.5%, a compressive strength of 1724MPa-1803MPa, and a hardness of 333HV-405HV.

[0007] 2. Technical scheme

[0008] In order to solve the above problems, the technical scheme adopted by the present application is as follows:

[0009] The preparation method of the carbon dot reinforced titanium-based composite material based on spark plasma sintering of the present application mainly uses biomass carbon dots combined with spark plasma sintering technology to effectively enhance the mechanical properties of titanium-based composite material.

[0010] Specifically, the method comprises the following steps:

[0011] Step S1, preparing biomass carbon dots;

[0012] Step S2, batching;

[0013] The biomass carbon dots obtained in step S1 and TC4 powder are mixed for batching, wherein the addition amount of biomass carbon dots accounts for 0.5-2.35% of the total weight of raw material powder;

[0014] Step S3, mixing, ball milling and drying;

[0015] After the batched raw materials are uniformly mixed, ball milling and drying treatment are carried out;

[0016] Step S4, sintering and cooling;

[0017] The treated raw material powder is sintered by SPS, and after sintering, it is cooled to room temperature to obtain a titanium-based composite material.

[0018] Further, in step S1, the biomass carbon dots use agricultural waste (rice straw, wheat straw, etc.) as raw material, and use hydrothermal method to prepare high-quality biomass carbon dots in batches, which solves the problem of high cost and low utilization rate of agricultural waste, establishes a convenient, cheap and efficient management and recycling system, and truly realizes the development concept of efficient utilization of solid waste. Specifically, the preparation method of biomass carbon dots in the present application is as follows:

[0019] The raw material is crushed and ground to about 150 meshes, then dissolved in 20-60 ml of deionized water, ultrasonically mixed and uniformly placed in a high-pressure reaction kettle, reacted at a temperature of 160-240 DEG C for 5-12 h in a forced air drying oven, a deep yellow solution is obtained, and the solution is poured into a centrifuge tube, the centrifuge speed is controlled at 6000-10000 r / min, the centrifugation time is 4-14 min, and the operation is repeated three times, the supernatant obtained is placed in a dialysis bag, the specification of the dialysis bag is 400-1000 KD, the dialysis time is 15-30 h, after dialysis, freeze-drying is carried out, the freeze-drying temperature is-80 DEG C, and the freeze-drying time is 30-48 h, and finally the biomass carbon dots are obtained.

[0020] The technical scheme of the present application has the following advantages: on the one hand, the biomass carbon dots are prepared by using agricultural wastes (rice straw, wheat straw, etc.) as raw materials, which saves cost, reduces energy consumption, fully utilizes renewable resources, and realizes maximum utilization of resources; on the other hand, the biomass carbon dots are combined with the discharge plasma sintering technology to efficiently and quickly prepare titanium-based composite materials with high density and excellent mechanical properties, and part of the carbon dots are in-situ synthesized to form TiCp reinforced phase reinforced titanium-based composite materials with small grain size, and the interface bonding strength of the biomass carbon dots is high, and the distribution of the reinforced phase is more uniform.

[0021] It should be noted that when the biomass carbon dots are used for reinforcement, the amount of carbon dots added needs to be strictly controlled, too much carbon dots will greatly reduce the plasticity of the composite material, and too little carbon dots will not have obvious reinforcement effect, the applicant has found through many experiments that when the amount of carbon dots added is controlled within this range (0.5-2.35%), the content of the reinforced phase in the obtained material can be effectively controlled, the content of the reinforced phase is about 1.75%, and the mechanical properties of the prepared titanium-based composite material are most significantly enhanced.

[0022] As a further improvement of the present application, the particle size of the TC4 is 15-130 μm, and the particle size of the biomass carbon dots is less than 10 nm, compared with micron-sized ordinary carbon sources, the particle size of the biomass carbon dots of the present application is less than 10 nm, which is combined more closely and uniformly with the matrix after ball milling, and is not easy to produce the agglomeration phenomenon of ordinary carbon sources, and in the subsequent in-situ reaction, the size of the generated TiC reinforced phase is also more uniform and small, which can effectively avoid the cracking phenomenon caused by stress concentration when subjected to pressure.

[0023] As a further improvement of the present application, in step S3, the prepared material is ball milled according to a ball-to-material ratio of (3-5):1, and alcohol is added for mixing during ball milling.

[0024] As a further improvement of the application, the ball milling rotation speed is 100-250 r / min, and the ball milling time is 4-16 h. By adjusting the ball milling rotation speed and the ball milling time, the carbon dots can be adhered to the surface of the TC4 powder without damaging the TC4 powder. During sintering, the carbon dots react with TC4 to form TiC reinforcing phase, and the TiC reinforcing phase presents a quasi-continuous network structure, which surrounds the TC4 matrix, in line with the H-S theory that the hard reinforcing phase surrounds the matrix, thereby greatly improving the mechanical properties of the material. In addition, due to the unique distribution of the reinforcing phase, the grain growth is also limited, so that the grain size of the prepared composite material is smaller. In addition, the reinforcing phase in a network distribution can effectively bear the load when subjected to external force, thereby improving the mechanical properties of the material and avoiding cracking caused by stress concentration.

[0025] As a further improvement of the application, in step S3, the drying temperature is 60-75℃, and the drying time is 10-24 h.

[0026] As a further improvement of the application, in step S4, the SPS sintering temperature is 1000-1150℃, the heating rate is 100℃ / min, the sintering pressure is 50 MPa, and the sintering time is 5-15 min. The SPS sintering can quickly prepare a dense titanium-based composite material with excellent mechanical properties. In addition, the fast heating rate of SPS inhibits grain growth, and it is a fast, efficient and energy-saving sintering method, which conforms to the concepts of cost saving, energy saving and recycling, and meets the concept of sustainable development.

[0027] As a further improvement of the application, the titanium-based composite material is prepared by the above method, and the grain size of the titanium-based composite material is 90 μm, the density is more than 99.5%, the compressive strength is 1724-1803 MPa, the yield strength is 1056-1176 MPa, the hardness is 333-405 HV, and the engineering strain is more than 28.36%.

[0028] 3. Beneficial effects

[0029] Compared with the prior art, the beneficial effects of the application are:

[0030] (1) The preparation method of the carbon dot reinforced titanium-based composite material based on spark plasma sintering effectively solves the problem of the relatively poor mechanical properties of the titanium-based composite material prepared by the traditional C source + SPS technology, i.e., the hardness is about 350 HV, and the compressive strength is about 1600 MPa. In the application, the biomass carbon dots are used, and the addition amount is optimized and designed, and the SPS technology is combined, so that the hardness of the prepared titanium-based composite material is up to 405 HV, and the compressive strength is up to 1803 MPa, which is increased by 15.7% and 12.7% respectively compared with the traditional C source.

[0031] (2) The preparation method of the carbon dot enhanced titanium-based composite material based on spark plasma sintering of the application, on the one hand, agricultural waste (rice straw, straw, etc.) is used as raw material to prepare biomass carbon dots, which saves cost, reduces energy consumption, fully utilizes renewable resources, and realizes maximum utilization of resources; On the other hand, the biomass carbon dots are combined with the spark plasma sintering technology to efficiently and quickly prepare titanium-based composite materials with high density and excellent mechanical properties. Some carbon dots are in-situ synthesized to form TiCp reinforced phase reinforced titanium-based composite materials with small grain size. The titanium-based composite material prepared has a density of more than 99.5%, a compressive strength of 1724MPa-1803MPa, a yield strength of 1056-1176MPa, a hardness of 333HV-405HV, and a strain of more than 28.36%. At the same time, the application uses agricultural waste as raw material to prepare biomass carbon dots, realizes efficient utilization, and fully meets the requirements of low cost, low energy consumption and sustainable concept. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is the appearance diagram of the titanium-based composite material sample obtained in Example 1 of the application.

[0033] Figure 2 It is the compression performance diagram of the titanium-based composite material sample obtained in Example 1 of the application.

[0034] Figure 3 It is the micro-morphology (SEM) diagram of the titanium-based composite material sample obtained in Example 1 of the application. DETAILED DESCRIPTION

[0035] The specific embodiments of the application will be further described below in combination with specific examples. It should be noted that the description of these embodiments is used to help understand the application, but does not constitute a limitation on the application.

[0036] Example 1

[0037] Step one, preparation of biomass carbon dots;

[0038] 4.23g of straw was crushed and ground to about 100 mesh and then dissolved in 25ml of deionized water. After ultrasonic mixing, it was put into a high-pressure reaction kettle. Through the air drying oven, it was reacted at 220℃ for 10h to obtain a dark yellow solution. The solution was poured into a centrifuge tube and centrifuged at a speed of 9000r / min for 9min. This operation was repeated three times. The supernatant was put into a 900KD dialysis bag and dialyzed for 19h. After dialysis, freeze-drying was carried out, the freezing temperature was-80℃, and the freezing time was 42h. Finally, 0.61g of biomass carbon dots was obtained.

[0039] Step two, preparation of biomass carbon dots and TC4 powder mixture;

[0040] 11.76g of TC4 powder (particle size of 50-100 μm) and the carbon dots obtained in step one (0.24g) were mixed in a ball milling tank; stainless steel balls were weighed according to a ball-to-powder ratio of 5:1, and an appropriate amount of alcohol was added, and the mixture was ball milled at a speed of 180 r / min for 12 h; the mixed powder after ball milling was placed in a drying oven and dried at 70℃ for 12 h.

[0041] Step three, SPS sintering;

[0042] The dried mixed powder was loaded into a graphite mold for SPS sintering, the sintering temperature was 1100℃, and the time was 10 min. After cooling to room temperature, the sample was taken out, and a non-continuous reinforced titanium-based composite material with a size of 15 mm in diameter and 13 mm in height was obtained, and the appearance was as shown in Figure 1

[0043] The obtained product was subjected to mechanical property detection, and the detection results are shown in Table 1.

[0044] Figure 2 The compression performance graph of the product sample obtained in this embodiment is shown, and from the graph, it can be seen that the compressive strength and yield strength reach 1803 MPa and 1176 MPa respectively, and the engineering strain reaches more than 28.36%, and the mechanical properties are excellent.

[0045] Figure 3 The micro-morphology (SEM) graph of the product sample obtained in this embodiment is shown, and the reinforcing phase presents a quasi-continuous network distribution, which greatly improves the mechanical properties of the composite material without cutting the matrix and material plasticity. Due to the special distribution of the reinforcing phase, the growth of the crystal grains is limited, and the grain size of the prepared composite material is less than 90 μm.

[0046] Example 2

[0047] Step one, preparation of biomass carbon dots;

[0048] 3.68g of wheat straw was crushed and ground to about 150 mesh, then dissolved in 35ml of deionized water, ultrasonically mixed uniformly, then placed in a high-pressure reaction kettle, and dried by a blowing drying oven at 200℃ for 8h to obtain a dark yellow solution. The solution was poured into a centrifuge tube and centrifuged at a speed of 8000r / min for 7min, and this operation was repeated three times. The supernatant obtained was placed in a 700KD dialysis bag and dialyzed for 17h. After dialysis, freeze-drying was performed, the freezing temperature was-80℃, and the freezing time was 36h. Finally, 0.58g of biomass carbon dots was obtained.

[0049] Step two, mixing of biomass carbon dots and TC4 powder;

[0050] ​Mix 11.94 g of TC4 powder (particle size of 30-80 μm) and the carbon dots obtained in step one (take 0.06 g) together in a ball milling tank; according to the ball-to-material ratio of 3:1, take stainless steel balls, add appropriate amount of alcohol, and ball mill at a speed of 200 r / min for 8 h; put the mixed powder ball milled into a drying box, and dry at 65 ℃ for 16 h.

[0051] Step three, SPS sintering;

[0052] Put the dried mixed powder into a graphite mold for SPS sintering, the sintering temperature is 1050 ℃, and the time is 12 min. After cooling to room temperature, take out the sample, and obtain a non-continuous reinforced titanium-based composite material with a size of diameter 15 mm and height 13 mm.

[0053] The obtained product is subjected to mechanical property detection, and the detection results are shown in Table 1.

[0054] Example 3

[0055] Step one, preparation of biomass carbon dots;

[0056] Grind 3 g of wheat straw to about 150 mesh, dissolve in 40 ml of deionized water, ultrasonically mix uniformly, and then put into a high-pressure reaction kettle. Through a forced air drying oven, react at 160 ℃ for 6 h to obtain a dark yellow solution. Pour the solution into a centrifuge tube and centrifuge at a speed of 6000 r / min for 5 min. Repeat this operation three times. Put the obtained supernatant into a 500 KD dialysis bag and dialyze for 15 h. After dialysis, freeze-dry, freeze at -80 ℃, and freeze for 30 h. Finally, 0.55 g of biomass carbon dots are obtained.

[0057] Step two, mixing of biomass carbon dots and TC4 powder;

[0058] Mix 11.82 g of TC4 powder (particle size of 15-50 μm) and the carbon dots obtained in step one (take 0.18 g) together in a ball milling tank; according to the ball-to-material ratio of 5:1, take stainless steel balls, add appropriate amount of alcohol, and ball mill at a speed of 250 r / min for 4 h; put the mixed powder ball milled into a drying box, and dry at 60 ℃ for 20 h.

[0059] Step three, SPS sintering;

[0060] Put the dried mixed powder into a graphite mold for SPS sintering, the sintering temperature is 1000 ℃, and the time is 15 min. After cooling to room temperature, take out the sample, and obtain a non-continuous reinforced titanium-based composite material with a size of diameter 15 mm and height 13 mm.

[0061] Example 4

[0062] Step one, preparation of biomass carbon dots;

[0063] 4.67 g of wheat straw was broken and ground to about 100 mesh, then dissolved in 20 ml of deionized water, ultrasonically mixed uniformly, then put into a high-pressure reaction kettle, reacted at 240℃ for 12 h by blowing dry box, a dark yellow solution was obtained, and the solution was poured into a centrifuge tube and centrifuged at 10000 r / min for 10 min, this operation was repeated three times, the supernatant was put into a 1000 KD dialysis bag and dialyzed for 20 h, after dialysis, freeze-drying was carried out, the freezing temperature was-80℃, and the freezing time was 48 h, finally 0.64 g of carbon dots was obtained.

[0064] Step two, mixing of carbon dots and TC4 powder;

[0065] 11.72 g of TC4 powder (particle size 70-130 μm) and 0.28 g of carbon dots obtained in step one were mixed in a ball mill jar; according to the ball-to-material ratio of 4:1, stainless steel balls were weighed, and appropriate amount of alcohol was added, and ball milling was carried out at a speed of 150 r / min for 16 h; the mixed powder after ball milling was put into a drying oven and dried at 75℃ for 10 h.

[0066] Step three, SPS sintering;

[0067] The dried mixed powder was loaded into a graphite mold for SPS sintering, the sintering temperature was 1150℃, and the time was 7 min. After cooling to room temperature, the sample was taken out, and a non-continuous reinforced titanium-based composite material with a size of diameter 15 mm and height 13 mm was obtained.

[0068] The obtained product was subjected to mechanical property detection, and the detection results are shown in Table 1.

[0069] Table 1 Performance detection indexes of titanium-based composite material samples obtained in each example

[0070] Item Grain size Density Compressive strength Yield strength Hardness Engineering strain Example 1 55 μm 99.65％ 1803 MPa 1176 MPa 405 HV 28.36％ Example 2 61 μm 99.72％ 1788 MPa 1056 MPa 382 HV 27.65％ Example 3 56 μm 99.54％ 1735 MPa 1067 MPa 356 HV 29.41％ Example 4 85 μm 99.68％ 1724 MPa 1123 MPa 333 HV 29.66％

[0071] More specifically, although illustrative embodiments of the application have been described herein, the present application should be understood to include any and all embodiments falling within the scope of the application as defined by the appended claims, and their equivalents. The limitations in the claims are to be construed as limiting only to the precise language used in the claims. Accordingly, the breadth and scope of the present application should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. Any and all limitations which can be present in any one of the foregoing aspects should be seen as applicable to each and every aspect of the present application. Thus, the breadth and scope of the present application should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. If there is a conflict between the definitions in the specification and those in the accompanying claims, the definitions in the claims should be construed as aligning the claim with the specification. Ranges, preferably ranges of values, or upper and lower preferred values, for rates, pressures, temperatures, times, or other values or parameters are intended to include every value and subset between the upper and lower preferred values, even if not expressly stated. For example, a range of 1-50 is to be interpreted as including any number, combination of numbers, or sub-range selected from the integers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50, as well as all decimal values between the integers, e.g., 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. With respect to sub-ranges, "nested sub-ranges" extending from either end of the range are specifically contemplated. For example, nested sub-ranges of the exemplary range 1-50 can include 1-10, 1-20, 1-30, and 1-40 in one direction, or 50-40, 50-30, 50-20, and 50-10 in the other direction.

Claims

1. A method for preparing a carbon dot enhanced titanium-based composite material based on spark plasma sintering, characterized in that, The method comprises the following steps: Step S1, preparing biomass carbon dots; Step S2, batching; The biomass carbon dots obtained in step S1 and TC4 powder are mixed for batching, wherein the biomass carbon dots are added in an amount of 0.5% to 2.35% of the total weight of the raw material powder; Step S3, mixing, ball milling and drying; After the batched raw material is uniformly mixed, ball milling and drying are performed; Step S4, sintering and cooling; The treated raw material powder is sintered by SPS, and after sintering, cooling to room temperature is performed, thereby obtaining a titanium-based composite material.

2. The method according to claim 1, wherein the method is characterized by: The particle size of the TC4 is 15-130 μm.

3. The method according to claim 1, wherein the method is characterized by: The particle size of the biomass carbon dots is less than 10 nm.

4. The method according to claim 3, wherein the method is characterized by: In step S1, agricultural waste is used as a raw material, and biomass carbon dots are prepared by a hydrothermal method.

5. The method for preparing a spark plasma sintering based carbon dots enhanced titanium matrix composite according to any one of claims 1-4, characterized in that: In step S3, the batched material is ball milled at a ball-to-material ratio of (3-5):1, and alcohol is added for mixing during ball milling.

6. The method according to claim 5, wherein the method is characterized by: The ball milling speed is 100-250 r / min, and the ball milling time is 4-16 h.

7. The method for preparing a spark plasma sintering based carbon dots enhanced titanium matrix composite according to any one of claims 1-4, characterized in that: In step S3, the drying temperature is 60-75 °C, and the drying time is 10-24 h.

8. The method for preparing a spark plasma sintering based carbon dot enhanced titanium matrix composite according to any one of claims 1-4, characterized in that: In step S4, the SPS sintering temperature is 1000-1150 °C, the heating rate is 100 °C / min, the sintering pressure is 50 MPa, and the sintering time is 5-15 min.

9. A carbon dots enhanced titanium matrix composite based on spark plasma sintering, characterized by: The titanium-based composite material is prepared by the method of any one of claims 1-8.

10. The carbon dots enhanced titanium matrix composite based on spark plasma sintering according to claim 9, characterized in that: The titanium-based composite material has a grain size of less than 90 μm, a density of more than 99.5%, a compressive strength of 1724-1803 MPa, a yield strength of 1056-1176 MPa, a hardness of 333-405 HV, and an engineering strain of more than 28.36%.

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