A surface nickel-plated PBO chopped fiber reinforced aluminum-based composite material and its preparation method

Abstract

This invention discloses a nickel-plated PBO chopped fiber reinforced aluminum matrix composite material and its preparation method, belonging to the technical field of metal matrix composites. The invention involves ultrasonic dispersion of fibers, fiber coarsening, nickel plating of the fiber surface, ball milling and mixing, spark plasma sintering, and subsequent high-temperature annealing to prepare the nickel-plated PBO fiber reinforced aluminum matrix composite material. By coating the surface of the PBO chopped fibers with a metallic nickel layer, the elemental diffusion and reaction process between the PBO chopped fibers and the aluminum matrix is ​​effectively promoted, generating a NiAl intermetallic compound reaction layer with good plasticity and toughness. This is beneficial for improving the interfacial bonding strength between the fiber and the matrix, thereby further improving the comprehensive mechanical properties of the composite material. The nickel-plated PBO chopped fiber reinforced aluminum matrix composite material has a density of over 99.0%, a maximum tensile yield strength of 270 MPa, a maximum tensile strength of 320 MPa, a maximum flexural strength of 435 MPa, and a maximum elongation after fracture of 14.0%, exhibiting excellent comprehensive mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of metal matrix composite technology, specifically relating to a nickel-plated PBO short fiber reinforced aluminum matrix composite material and its preparation method. Background Technology

[0002] Aluminum-based composites are composite materials with metallic aluminum or aluminum alloys as the matrix and continuous long fibers, short fibers, whiskers, and particles as reinforcing phases. They possess excellent comprehensive properties such as high specific strength, corrosion resistance, and low coefficient of thermal expansion, and are relatively inexpensive, making them promising for applications in aerospace, automotive, and armor protection industries. The research and application of aluminum-based composites began in the 1950s. Commonly used reinforcing materials include silicon carbide fibers, particles, carbon nanotubes (graphene, carbon nanotubes), and carbon fibers. Among these, carbon fibers have high strength and modulus, significantly strengthening the matrix. However, the interfacial reaction between the aluminum matrix and carbon fibers generates a brittle Al4C3 phase, which negatively impacts the overall performance of the composite material. Currently, carbon fiber reinforced aluminum-based composites are still in the research stage.

[0003] Compared to carbon fiber and silicon carbide fiber, PBO fiber (poly(p-phenylenebenzodioxazole) fiber) has higher strength and modulus, with a tensile strength reaching 5.8 GPa, and better plasticity (elongation after fracture: 3.5%), making it a more ideal reinforcement material. Simultaneously, PBO fiber exhibits superior impact resistance, high-temperature resistance, abrasion resistance, and dimensional stability, earning it the title of "super fiber of the 21st century." Therefore, compared to carbon fiber, PBO fiber can more effectively improve the comprehensive mechanical properties of aluminum matrix composites. However, the smooth surface of PBO fiber, lacking polar groups, and the absence of elemental diffusion or reaction with the aluminum matrix during sintering to form interfacial products, results in limited interfacial bonding strength between the fiber and the aluminum matrix, hindering further improvement in the comprehensive mechanical properties of the composite material. Surface nickel plating refers to coating the surface of fibers, such as fibers, with a layer of metallic nickel using chemical plating or electroplating processes. This promotes the formation of an interfacial phase between the fiber surface and the metal matrix through diffusion or reaction, thereby improving the interfacial bonding strength. However, research on surface nickel-plated PBO fiber reinforced aluminum matrix composites has not yet been conducted. Based on this, it remains to be seen whether nickel-plated PBO fibers can further improve the comprehensive mechanical properties of aluminum matrix composites, and how to prepare nickel-plated PBO fiber reinforced aluminum matrix composites. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a nickel-plated PBO chopped fiber reinforced aluminum matrix composite material and its preparation method. First, PBO chopped fibers are dispersed and coarsened using an ultrasonic dispersion device. Then, a layer of metallic nickel is coated onto the surface of the PBO chopped fibers using a chemical nickel plating process. Next, the nickel-plated PBO chopped fibers and aluminum powder are placed in a ball mill jar at a predetermined ratio and ball-milled using a three-dimensional planetary vibrating ball mill to ensure thorough and uniform mixing, resulting in a mixture. The mixture is then placed in a cemented carbide mold and sintered in a spark plasma sintering furnace (SPS) under high temperature and high pressure conditions to obtain a composite material preform. Finally, the composite material preform is placed in a vacuum atmosphere sintering furnace for high-temperature annealing to obtain the nickel-plated PBO chopped fiber reinforced aluminum matrix composite material, thereby achieving the objective of this invention.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A method for preparing a nickel-plated PBO short-fiber reinforced aluminum matrix composite material, the method comprising the following steps:

[0007] (1) Place the PBO short-cut fibers in an ultrasonic dispersion device, add anhydrous ethanol, and perform ultrasonic dispersion treatment. After dispersion, filter out the fibers and dry them.

[0008] (2) The PBO chopped fibers treated in step (1) are immersed in concentrated sulfuric acid for roughening treatment. The concentration of concentrated sulfuric acid is 60~90%, the immersion time is 10~40s, and the fibers are rinsed with deionized water after immersion to obtain PBO chopped fibers to be plated.

[0009] (3) Prepare the electroless nickel plating solution. The solvents used include: nickel sulfate hexahydrate, sodium citrate, sodium hypophosphite, sodium pyrophosphate, pH adjuster, and deionized water, of which Ni 2+ The concentration of sodium citrate is 0.02~0.08 mol / L, the concentration of sodium hypophosphite is 0.01~0.10 mol / L, the concentration of sodium hypophosphite is 0.05~0.20 mol / L, the concentration of sodium pyrophosphate is 0.10~0.30 mol / L, the pH adjuster is NaOH, KOH or ammonia, and the pH value of the nickel plating solution is 9~13;

[0010] (4) Immerse PBO short-cut fibers in nickel plating solution, add iron as reaction medium and sodium hypophosphite as reducing agent. The concentration of sodium hypophosphite is 10~45g / L. Perform chemical nickel plating treatment under ultrasonic stirring. The ultrasonic frequency is 10~20kHz, the nickel plating temperature is 50~90℃, and the nickel plating reaction time is 60~150min. After nickel plating, rinse the fibers with deionized water 7~10 times and dry them at 70~120℃ to obtain nickel-plated PBO short-cut fibers.

[0011] (5) Mix nickel-plated PBO short chopped fibers and aluminum powder and put them into a ball mill jar. The mass fraction of nickel-plated PBO short chopped fibers is 2~10wt%. Add alumina grinding balls to the mixture. The ball-to-material ratio is 2~8:1.

[0012] (6) The ball milling jar is fixed in a three-dimensional planetary vibrating ball mill for ball milling and mixing. The ball milling speed is 100~500r / min and the ball milling time is 2~8h to obtain a uniformly mixed nickel-plated PBO short fiber / aluminum powder mixture.

[0013] (7) The mixture is placed in a hard alloy mold and sintered in a spark plasma sintering furnace (SPS) at a temperature of 450~600℃, a sintering pressure of 100~300MPa, and a holding time of 10~45min. After sintering, the mold is removed to obtain a nickel-plated PBO short fiber reinforced aluminum matrix composite blank.

[0014] (8) The nickel-plated PBO short fiber reinforced aluminum matrix composite blank is placed in a vacuum atmosphere sintering furnace for high-temperature annealing treatment. The annealing temperature is 300~500℃ and the annealing holding time is 1~4h. After annealing, it is cooled to room temperature with the furnace to obtain the nickel-plated PBO short fiber reinforced aluminum matrix composite.

[0015] Preferably, in step (2), the length of the PBO chopped fiber is 1~6mm, the concentration of the concentrated sulfuric acid used for the roughening treatment is 70~80%, and the soaking time is 20~40s;

[0016] Preferably, in step (3), the Ni in the nickel plating solution 2+ The concentration of sodium sulfate is 0.03~0.06 mol / L, the concentration of sodium citrate is 0.02~0.05 mol / L, the concentration of sodium hypophosphite is 0.10~0.16 mol / L, the concentration of sodium pyrophosphate is 0.15~0.25 mol / L, and the pH value of the nickel plating solution is 10~12;

[0017] Preferably, in step (4), the sodium hypophosphite concentration is 15~30 g / L, the nickel plating temperature is 60~80℃, and the nickel plating reaction time is 80~120 min;

[0018] Preferably, in step (5), the aluminum powder particle size is 20~200μm, the nickel-plated PBO short fiber mass fraction is 3~7wt%, and the ball-to-material ratio is 3~6∶1;

[0019] Preferably, in step (6), the ball milling speed is 200~400 r / min and the ball milling time is 3~5 h;

[0020] Preferably, in step (7), the discharge plasma sintering temperature is 475~575℃, the sintering pressure is 150~250MPa, and the holding time is 15~30min;

[0021] Preferably, in step (8), the high-temperature annealing temperature is 350~450℃ and the annealing holding time is 2~3h.

[0022] A nickel-plated PBO short fiber reinforced aluminum matrix composite material was prepared by the above method.

[0023] The beneficial effects of this invention are:

[0024] (1) The present invention relates to a nickel-plated PBO short-fiber reinforced aluminum matrix composite material and its preparation method. The preparation process of the composite material includes ultrasonic dispersion of PBO short-fibers, nickel plating on the fiber surface, ball milling and mixing, spark plasma sintering and subsequent high-temperature annealing. Before nickel plating, the PBO short-fibers are roughened to make their surface rough, which is beneficial to increase the bonding force between the fiber and the nickel plating layer, thereby facilitating the subsequent nickel plating process.

[0025] (2) The nickel plating reaction temperature and time have an important influence on the nickel plating effect and the comprehensive mechanical properties of the composite material: When the nickel plating reaction temperature is too low and the reaction time is too short, the degree of chemical reaction is low, resulting in a thinner and unevenly distributed nickel plating layer on the PBO surface, which is not dense, resulting in limited interfacial bonding force between the fiber and the aluminum matrix; while if the nickel plating reaction time is too long, on the one hand, the nickel plating layer thickness will be too large, and the uneven plating layer thickness will easily occur, resulting in a reduction in the interfacial bonding strength of the composite material; on the other hand, the nickel plating time is too long, which also leads to low nickel plating efficiency.

[0026] (3) The fiber reinforcement content in the composite material is 1wt%~10wt%. When the reinforcement content is less than 1wt%, its reinforcement effect on the matrix is ​​limited. When the reinforcement content is greater than 10wt%, the fibers are prone to agglomeration during ball milling and mixing, which reduces its reinforcement effect. At the same time, the sintering method used is spark plasma sintering, which is different from conventional hot pressing sintering. Spark plasma sintering has a fast heating rate, which can greatly shorten the sintering time and improve the sintering efficiency. At the same time, the low temperature and high pressure sintering mode can effectively prevent damage to the PBO short-cut fibers and melting of the aluminum matrix caused by excessively high sintering temperature.

[0027] (4) During the spark plasma sintering process, the nickel plating layer on the surface of PBO fiber can undergo atomic diffusion and reaction with the aluminum matrix to generate a NiAl intermetallic compound reaction layer with good plasticity and toughness, thereby effectively improving the interfacial bonding force between the fiber reinforcement and the aluminum matrix, and can more effectively play the role of the fiber reinforcement, thereby further improving the comprehensive mechanical properties of aluminum matrix composites.

[0028] (5) The present invention relates to a PBO chopped fiber reinforced aluminum matrix composite material and its preparation method. The PBO chopped fiber has a good reinforcing effect on the aluminum matrix. The PBO chopped fiber reinforced aluminum matrix composite material has a density of more than 99.0%, a maximum tensile yield strength of up to 270 MPa (pure aluminum yield strength < 70 MPa), a maximum tensile strength of up to 320 MPa (pure aluminum tensile strength < 90 MPa), and a maximum flexural strength of up to 435 MPa (pure aluminum flexural strength < 120 MPa). At the same time, the PBO chopped fiber reinforced aluminum matrix composite material has good plastic deformation ability, and its maximum elongation after fracture can reach 14.0%, which has good comprehensive mechanical properties. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below with reference to the embodiments. Obviously, the embodiments described herein are only used to explain the present invention, but the present invention is not limited to these embodiments.

[0030] In the following embodiments:

[0031] (1) Density testing equipment: JA2003 electronic balance.

[0032] (2) Tensile testing equipment: The INSTRON5985 electronic universal testing machine (Instrand, USA) was used.

[0033] (3) Yield strength, tensile strength and elongation were measured by tensile stress-strain curves obtained from tensile tests in accordance with GB / T228-2002.

[0034] (4) The bending strength was measured using an INSTRON5985 electronic universal testing machine (Instrand, USA) in accordance with GB / T232-2010 "Metallic Materials Bending Test Method".

[0035] Example 1

[0036] This embodiment prepares a nickel-plated PBO short fiber reinforced aluminum matrix composite material, as follows:

[0037] (1) Place the PBO short-cut fibers in an ultrasonic dispersion device, add anhydrous ethanol, and perform ultrasonic dispersion treatment. After dispersion, filter out the fibers and dry them.

[0038] (2) The PBO chopped fibers after step (1) are immersed in concentrated sulfuric acid for roughening treatment. The length of the PBO chopped fibers is 1 mm, the concentration of concentrated sulfuric acid is 60%, and the immersion time is 40 s to obtain the PBO chopped fibers to be plated.

[0039] (3) Prepare the electroless nickel plating solution. The solvents used include: nickel sulfate hexahydrate, sodium citrate, sodium hypophosphite, sodium pyrophosphate, pH adjuster, and deionized water, of which Ni 2+ The concentration of sodium chloride is 0.02 mol / L, the concentration of sodium citrate is 0.01 mol / L, the concentration of sodium hypophosphite is 0.20 mol / L, the concentration of sodium pyrophosphate is 0.30 mol / L, the pH adjuster is NaOH, and the pH value of the nickel plating solution is 9.

[0040] (4) Immerse PBO short-cut fibers in nickel plating solution, add iron as reaction medium and sodium hypophosphite as reducing agent, with a concentration of 10 g / L, and perform chemical nickel plating under ultrasonic stirring. The ultrasonic frequency is 10~20 kHz, the nickel plating temperature is 50℃, and the nickel plating reaction time is 60 min. After nickel plating, rinse the fibers with deionized water 7~10 times and dry them at 70~120℃ to obtain nickel-plated PBO short-cut fibers.

[0041] (5) Mix nickel-plated PBO short chopped fibers and aluminum powder and put them into a ball mill jar. The aluminum powder has a particle size of 20 μm and the nickel-plated PBO short chopped fibers have a mass fraction of 2 wt%. Add alumina grinding balls to the mixture. The ball-to-material ratio is 2:1.

[0042] (6) The ball mill jar was fixed in a three-dimensional planetary vibrating ball mill for ball milling and mixing. The ball milling speed was 100 r / min and the ball milling time was 8 h to obtain a uniformly mixed material of nickel-plated PBO short-cut fibers / aluminum powder.

[0043] (7) The mixture is placed in a hard alloy mold and sintered in a spark plasma sintering furnace (SPS) at a temperature of 450°C, a sintering pressure of 300 MPa, and a holding time of 45 min. After sintering, the mold is removed to obtain a nickel-plated PBO short fiber reinforced aluminum matrix composite blank.

[0044] (8) The nickel-plated PBO short fiber reinforced aluminum matrix composite material blank was placed in a vacuum atmosphere sintering furnace for high-temperature annealing. The annealing temperature was 300℃ and the annealing holding time was 4h. After annealing, it was cooled to room temperature with the furnace to obtain the nickel-plated PBO short fiber reinforced aluminum matrix composite material.

[0045] The PBO chopped fiber reinforced aluminum matrix composite material prepared in this embodiment has a density of 99.3%, a tensile yield strength of 265 MPa, a tensile strength of 310 MPa, a flexural strength of 420 MPa, and an elongation after fracture of 13.5%, exhibiting good comprehensive mechanical properties.

[0046] Example 2

[0047] This embodiment prepares a nickel-plated PBO short fiber reinforced aluminum matrix composite material, as follows:

[0048] (1) Place the PBO short-cut fibers in an ultrasonic dispersion device, add anhydrous ethanol, and perform ultrasonic dispersion treatment. After dispersion, filter out the fibers and dry them.

[0049] (2) The PBO chopped fibers after step (1) are immersed in concentrated sulfuric acid for roughening treatment. The length of the PBO chopped fibers is 6 mm, the concentration of concentrated sulfuric acid is 90%, and the immersion time is 10 s to obtain the PBO chopped fibers to be plated.

[0050] (3) Prepare the electroless nickel plating solution. The solvents used include: nickel sulfate hexahydrate, sodium citrate, sodium hypophosphite, sodium pyrophosphate, pH adjuster, and deionized water, of which Ni 2+ The concentration of sodium chloride is 0.08 mol / L, sodium citrate is 0.10 mol / L, sodium hypophosphite is 0.05 mol / L, sodium pyrophosphate is 0.10 mol / L, the pH adjuster is KOH, and the pH value of the nickel plating solution is 13.

[0051] (4) Immerse PBO short-cut fibers in nickel plating solution, add iron as reaction medium and sodium hypophosphite as reducing agent, with a concentration of 45 g / L, and perform chemical nickel plating under ultrasonic stirring. The ultrasonic frequency is 10~20 kHz, the nickel plating temperature is 90℃, and the nickel plating reaction time is 150 min. After nickel plating, rinse the fibers with deionized water 7~10 times and dry them at 70~120℃ to obtain nickel-plated PBO short-cut fibers.

[0052] (5) Mix the nickel-plated PBO short chopped fibers and aluminum powder and put them into a ball mill jar. The aluminum powder has a particle size of 200 μm and the nickel-plated PBO short chopped fibers have a mass fraction of 10 wt%. Add alumina grinding balls to the mixture. The ball-to-material ratio is 8:1.

[0053] (6) The ball mill jar was fixed in a three-dimensional planetary vibrating ball mill for ball milling and mixing. The ball milling speed was 500 r / min and the ball milling time was 2 h to obtain a uniformly mixed nickel-plated PBO short fiber / aluminum powder mixture.

[0054] (7) The mixture is placed in a hard alloy mold and sintered in a spark plasma sintering furnace (SPS) at a temperature of 600°C and a pressure of 100MPa. The holding time is 10min. After sintering, the mold is removed to obtain a nickel-plated PBO short fiber reinforced aluminum matrix composite blank.

[0055] (8) The nickel-plated PBO short fiber reinforced aluminum matrix composite material blank was placed in a vacuum atmosphere sintering furnace for high-temperature annealing. The annealing temperature was 500℃ and the annealing holding time was 1h. After annealing, it was cooled to room temperature with the furnace to obtain the nickel-plated PBO short fiber reinforced aluminum matrix composite material.

[0056] The PBO chopped fiber reinforced aluminum matrix composite material prepared in this embodiment has a density of 99.3%, a tensile yield strength of 270 MPa, a tensile strength of 320 MPa, a flexural strength of 430 MPa, and an elongation after fracture of 13.8%, exhibiting good comprehensive mechanical properties.

[0057] Example 3

[0058] This embodiment prepares a nickel-plated PBO short fiber reinforced aluminum matrix composite material, as follows:

[0059] (1) Place the PBO short-cut fibers in an ultrasonic dispersion device, add anhydrous ethanol, and perform ultrasonic dispersion treatment. After dispersion, filter out the fibers and dry them.

[0060] (2) The PBO chopped fibers after step (1) are immersed in concentrated sulfuric acid for roughening treatment. The length of the PBO chopped fibers is 3 mm, the concentration of concentrated sulfuric acid is 70%, and the immersion time is 20 s to obtain the PBO chopped fibers to be plated.

[0061] (3) Prepare the electroless nickel plating solution. The solvents used include: nickel sulfate hexahydrate, sodium citrate, sodium hypophosphite, sodium pyrophosphate, pH adjuster, and deionized water, of which Ni 2+ The concentration of sodium chloride is 0.03 mol / L, sodium citrate is 0.02 mol / L, sodium hypophosphite is 0.10 mol / L, sodium pyrophosphate is 0.15 mol / L, the pH adjuster is KOH, and the pH value of the nickel plating solution is 10.

[0062] (4) Immerse PBO short-cut fibers in nickel plating solution, add iron as reaction medium and sodium hypophosphite as reducing agent, with a concentration of 15 g / L, and perform chemical nickel plating under ultrasonic stirring. The ultrasonic frequency is 10~20 kHz, the nickel plating temperature is 60℃, and the nickel plating reaction time is 80 min. After nickel plating, rinse the fibers with deionized water 7~10 times and dry them at 70~120℃ to obtain nickel-plated PBO short-cut fibers.

[0063] (5) Mix nickel-plated PBO short chopped fibers and aluminum powder and put them into a ball mill jar. The aluminum powder has a particle size of 100 μm and the nickel-plated PBO short chopped fibers have a mass fraction of 7 wt%. Add alumina grinding balls to the mixture. The ball-to-material ratio is 3:1.

[0064] (6) The ball mill jar is fixed in a three-dimensional planetary vibrating ball mill for ball milling and mixing. The ball milling speed is 200 r / min and the ball milling time is 3 h to obtain a uniformly mixed nickel-plated PBO short fiber / aluminum powder mixture.

[0065] (7) The mixture is placed in a hard alloy mold and sintered in a spark plasma sintering furnace (SPS) at a temperature of 475°C and a pressure of 150 MPa. The holding time is 15 min. After sintering, the mold is removed to obtain a nickel-plated PBO short fiber reinforced aluminum matrix composite blank.

[0066] (8) The nickel-plated PBO short fiber reinforced aluminum matrix composite material blank was placed in a vacuum atmosphere sintering furnace for high-temperature annealing. The annealing temperature was 350℃ and the annealing holding time was 2h. After annealing, it was cooled to room temperature with the furnace to obtain the nickel-plated PBO short fiber reinforced aluminum matrix composite material.

[0067] The PBO chopped fiber reinforced aluminum matrix composite material prepared in this embodiment has a density of 99.1%, a tensile yield strength of 260 MPa, a tensile strength of 305 MPa, a flexural strength of 425 MPa, and an elongation after fracture of 13.0%, exhibiting good comprehensive mechanical properties.

[0068] Example 4

[0069] This embodiment prepares a nickel-plated PBO short fiber reinforced aluminum matrix composite material, as follows:

[0070] (1) Place the PBO short-cut fibers in an ultrasonic dispersion device, add anhydrous ethanol, and perform ultrasonic dispersion treatment. After dispersion, filter out the fibers and dry them.

[0071] (2) The PBO chopped fibers after step (1) are immersed in concentrated sulfuric acid for roughening treatment. The length of the PBO chopped fibers is 4 mm, the concentration of concentrated sulfuric acid is 80%, and the immersion time is 40 s to obtain the PBO chopped fibers to be plated.

[0072] (3) Prepare the electroless nickel plating solution. The solvents used include: nickel sulfate hexahydrate, sodium citrate, sodium hypophosphite, sodium pyrophosphate, pH adjuster, and deionized water, of which Ni 2+ The concentration of sodium citrate is 0.06 mol / L, the concentration of sodium hypophosphite is 0.16 mol / L, the concentration of sodium pyrophosphate is 0.25 mol / L, the pH adjuster is KOH, etc., and the pH value of the nickel plating solution is 12.

[0073] (4) Immerse PBO short-cut fibers in nickel plating solution, add iron as reaction medium and sodium hypophosphite as reducing agent, with a concentration of 30 g / L, and perform chemical nickel plating under ultrasonic stirring. The ultrasonic frequency is 10~20 kHz, the nickel plating temperature is 80 ℃, and the nickel plating reaction time is 120 min. After nickel plating, rinse the fibers with deionized water 7~10 times and dry them at 70~120 ℃ to obtain nickel-plated PBO short-cut fibers.

[0074] (5) Mix nickel-plated PBO short chopped fibers and aluminum powder and put them into a ball mill jar. The aluminum powder has a particle size of 120 μm and the nickel-plated PBO short chopped fibers have a mass fraction of 3 wt%. Add alumina grinding balls to the mixture. The ball-to-material ratio is 6:1.

[0075] (6) The ball mill jar was fixed in a three-dimensional planetary vibrating ball mill for ball milling and mixing. The ball milling speed was 400 r / min and the ball milling time was 5 h to obtain a uniformly mixed nickel-plated PBO short fiber / aluminum powder mixture.

[0076] (7) The mixture is placed in a hard alloy mold and sintered in a spark plasma sintering furnace (SPS) at a temperature of 575°C, a sintering pressure of 250 MPa, and a holding time of 30 min. After sintering, the mold is removed to obtain a nickel-plated PBO short fiber reinforced aluminum matrix composite blank.

[0077] (8) The nickel-plated PBO short fiber reinforced aluminum matrix composite material blank was placed in a vacuum atmosphere sintering furnace for high-temperature annealing. The annealing temperature was 450℃ and the annealing holding time was 3h. After annealing, it was cooled to room temperature with the furnace to obtain the nickel-plated PBO short fiber reinforced aluminum matrix composite material.

[0078] The PBO chopped fiber reinforced aluminum matrix composite material prepared in this embodiment has a density of 99.5%, a tensile yield strength of 255 MPa, a tensile strength of 295 MPa, a flexural strength of 420 MPa, and an elongation after fracture of 12.5%, exhibiting good comprehensive mechanical properties.

[0079] Example 5

[0080] This embodiment prepares a nickel-plated PBO short fiber reinforced aluminum matrix composite material, as follows:

[0081] (1) Place the PBO short-cut fibers in an ultrasonic dispersion device, add anhydrous ethanol, and perform ultrasonic dispersion treatment. After dispersion, filter out the fibers and dry them.

[0082] (2) The PBO chopped fibers after step (1) are immersed in concentrated sulfuric acid for roughening treatment. The length of the PBO chopped fibers is 5 mm, the concentration of concentrated sulfuric acid is 90%, and the immersion time is 30 s to obtain the PBO chopped fibers to be plated.

[0083] (3) Prepare the electroless nickel plating solution. The solvents used include: nickel sulfate hexahydrate, sodium citrate, sodium hypophosphite, sodium pyrophosphate, pH adjuster, and deionized water, of which Ni 2+ The concentrations of sodium citrate, sodium hypophosphite, sodium pyrophosphate, and KOH are 0.06 mol / L, respectively, and the pH value of the nickel plating solution is 11.

[0084] (4) Immerse PBO chopped fibers in nickel plating solution, add iron as reaction medium and sodium hypophosphite as reducing agent, with a concentration of 25 g / L, and perform chemical nickel plating under ultrasonic stirring. The ultrasonic frequency is 10~20 kHz, the nickel plating temperature is 70℃, and the nickel plating reaction time is 100 min. After nickel plating, rinse the fibers with deionized water 7~10 times and dry them at 70~120℃ to obtain nickel-plated PBO chopped fibers.

[0085] (5) Mix nickel-plated PBO short chopped fibers and aluminum powder and put them into a ball mill jar. The aluminum powder has a particle size of 80 μm and the nickel-plated PBO short chopped fibers have a mass fraction of 5 wt%. Add alumina grinding balls to the mixture. The ball-to-material ratio is 4:1.

[0086] (6) The ball mill jar was fixed in a three-dimensional planetary vibrating ball mill for ball milling and mixing. The ball milling speed was 200 r / min and the ball milling time was 4 h to obtain a uniformly mixed nickel-plated PBO short fiber / aluminum powder mixture.

[0087] (7) The mixture is placed in a hard alloy mold and sintered in a spark plasma sintering furnace (SPS) at a temperature of 550°C and a pressure of 200 MPa. The holding time is 20 min. After sintering, the mold is removed to obtain a nickel-plated PBO short fiber reinforced aluminum matrix composite blank.

[0088] (8) The nickel-plated PBO short fiber reinforced aluminum matrix composite material blank was placed in a vacuum atmosphere sintering furnace for high-temperature annealing. The annealing temperature was 400℃ and the annealing holding time was 2h. After annealing, it was cooled to room temperature with the furnace to obtain the nickel-plated PBO short fiber reinforced aluminum matrix composite material.

[0089] The PBO chopped fiber reinforced aluminum matrix composite material prepared in this embodiment has a density of 99.0%, a tensile yield strength of 263 MPa, a tensile strength of 314 MPa, a flexural strength of 419 MPa, and an elongation after fracture of 13.3%, exhibiting good comprehensive mechanical properties.

[0090] Comparative Example 1

[0091] The difference from Example 1 is as follows:

[0092] Instead of nickel plating the PBO chopped fibers, the PBO chopped fibers were dispersed, dried, and then mixed evenly with aluminum powder. The PBO chopped fiber reinforced aluminum matrix composite material was prepared by spark plasma sintering.

[0093] The PBO chopped fiber reinforced aluminum matrix composite material prepared in this comparative example has a density of 99.0%, a tensile yield strength of 205 MPa, a tensile strength of 255 MPa, a flexural strength of 350 MPa, and an elongation after fracture of 12.0%.

[0094] As can be seen from the comparison between Example 1 and this comparative example, under the same conditions of fiber reinforcement content, ball milling process, sintering process and annealing process, since the surface of PBO short chopped fiber was not nickel-plated, NiAl intermetallic compound was not generated at the interface between the fiber and the aluminum matrix during the sintering preparation process. Its interface bonding performance was poor, which led to a significant reduction in the yield strength, tensile strength and flexural strength of the composite material.

[0095] Comparative Example 2

[0096] The difference from Example 2 is as follows:

[0097] (4) Immerse PBO short-cut fibers in nickel plating solution, add iron as reaction medium and sodium hypophosphite as reducing agent, with a concentration of 45 g / L, and perform chemical nickel plating under ultrasonic stirring. The ultrasonic frequency is 10~20 kHz, the nickel plating temperature is room temperature (25℃), and the nickel plating reaction time is 150 min. After nickel plating, rinse the fibers with deionized water 7~10 times and dry them at 70~120℃ to obtain nickel-plated PBO short-cut fibers.

[0098] The PBO chopped fiber reinforced aluminum matrix composite material prepared in this comparative example has a density of 99.0%, a tensile yield strength of 225 MPa, a tensile strength of 260 MPa, a flexural strength of 380 MPa, and an elongation after fracture of 14.0%.

[0099] As can be seen from the comparison between Example 2 and this comparative example, under the same conditions of nickel plating solution composition ratio, nickel plating reaction time, fiber reinforcement content, ball milling process, sintering process and annealing process, due to the low nickel plating reaction temperature, the degree of reaction between the reactants during the nickel plating process is low, the thickness and density of the nickel plating layer on the surface of PBO fiber are poor, and thus the yield strength, tensile strength and flexural strength of the composite material are significantly reduced.

[0100] Comparative Example 3

[0101] The difference from Example 2 is as follows:

[0102] (4) Immerse PBO short-cut fibers in nickel plating solution, add iron as reaction medium and sodium hypophosphite as reducing agent, with a concentration of 45 g / L, and perform chemical nickel plating under ultrasonic stirring. The ultrasonic frequency is 10~20 kHz, the nickel plating temperature is 90℃, and the nickel plating reaction time is 300 min. After nickel plating, rinse the fibers with deionized water 7~10 times and dry them at 70~120℃ to obtain nickel-plated PBO short-cut fibers.

[0103] The PBO chopped fiber reinforced aluminum matrix composite material prepared in this comparative example has a density of 99.0%, a tensile yield strength of 235 MPa, a tensile strength of 270 MPa, a flexural strength of 375 MPa, and an elongation after fracture of 11.0%.

[0104] As can be seen from the comparison between Example 2 and this comparative example, under the same conditions of nickel plating solution composition ratio, nickel plating reaction temperature, fiber reinforcement content, ball milling process, sintering process and annealing process, due to the excessively long nickel plating reaction time, the nickel plating layer thickness on the surface of PBO chopped fibers is uneven after nickel plating treatment, which leads to a significant reduction in the yield strength, tensile strength, flexural strength and elongation after fracture of the composite material.

[0105] Comparative Example 4

[0106] The difference from Example 4 is as follows:

[0107] (7) The mixture is placed in a hard alloy mold and sintered in a spark plasma sintering furnace (SPS) at a temperature of 275°C and a pressure of 250 MPa. The holding time is 30 min. After sintering, the mold is removed to obtain a nickel-plated PBO short fiber reinforced aluminum matrix composite blank.

[0108] The PBO chopped fiber reinforced aluminum matrix composite material prepared in this comparative example has a density of 91.5%, a tensile yield strength of 120 MPa, a tensile strength of 145 MPa, a flexural strength of 190 MPa, and an elongation after fracture of 9.5%.

[0109] As can be seen from the comparison between Example 4 and this comparative example, under the same conditions of nickel plating process, fiber reinforcement content, ball milling process, sintering pressure, heat and pressure holding time and annealing temperature, when the sintering temperature is too low, the aluminum matrix and the nickel-plated PBO short-cut fibers cannot react sufficiently, resulting in the composite material not being able to be sintered densely. Its yield strength, tensile strength, flexural strength and elongation after fracture are significantly reduced, and good comprehensive mechanical properties cannot be achieved.

[0110] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.

Claims

1. A method for preparing a nickel-plated PBO chopped fiber reinforced aluminum matrix composite material, characterized in that, The method steps include: (1) Place the PBO short-cut fibers in an ultrasonic dispersion device, add anhydrous ethanol, and perform ultrasonic dispersion treatment. After dispersion, filter out the fibers and dry them. (2) The PBO chopped fibers treated in step (1) are immersed in concentrated sulfuric acid for roughening treatment. The concentration of concentrated sulfuric acid is 60~90% and the immersion time is 10~40s. After immersion, the fibers are rinsed with deionized water to obtain PBO chopped fibers to be plated. (3) Prepare the electroless nickel plating solution. The solvents used include: nickel sulfate hexahydrate, sodium citrate, sodium hypophosphite, sodium pyrophosphate, pH adjuster, and deionized water, of which Ni 2+ The concentration of sodium citrate is 0.02~0.08 mol / L, the concentration of sodium hypophosphite is 0.01~0.10 mol / L, the concentration of sodium hypophosphite is 0.05~0.20 mol / L, the concentration of sodium pyrophosphate is 0.10~0.30 mol / L, the pH adjuster is NaOH, KOH or ammonia, and the pH value of the nickel plating solution is 9~13; (4) Immerse PBO short-cut fibers in nickel plating solution, add iron as reaction medium and sodium hypophosphite as reducing agent. The concentration of sodium hypophosphite is 10~45g / L. Perform chemical nickel plating treatment under ultrasonic stirring. The ultrasonic frequency is 10~20kHz, the nickel plating temperature is 50~90℃, and the nickel plating reaction time is 60~150min. After nickel plating, rinse the fibers with deionized water 7~10 times and dry them at 70~120℃ to obtain nickel-plated PBO short-cut fibers. (5) Mix nickel-plated PBO short chopped fibers and aluminum powder and put them into a ball mill jar. The mass fraction of nickel-plated PBO short chopped fibers is 2~10wt%. Add alumina grinding balls to the mixture. The ball-to-material ratio is 2~8:

1. (6) The ball milling jar is fixed in a three-dimensional planetary vibrating ball mill for ball milling and mixing. The ball milling speed is 100~500r / min and the ball milling time is 2~8h to obtain a uniformly mixed nickel-plated PBO short fiber / aluminum powder mixture. (7) The mixture is placed in a hard alloy mold and sintered in a spark plasma sintering furnace (SPS) at a temperature of 450~600℃, a sintering pressure of 100~300MPa, and a holding time of 10~45min. After sintering, the mold is removed to obtain a nickel-plated PBO short fiber reinforced aluminum matrix composite blank. (8) The nickel-plated PBO short fiber reinforced aluminum matrix composite blank is placed in a vacuum atmosphere sintering furnace for high-temperature annealing treatment. The annealing temperature is 300~500℃ and the annealing holding time is 1~4h. After annealing, it is cooled to room temperature with the furnace to obtain the nickel-plated PBO short fiber reinforced aluminum matrix composite.

2. The method for preparing a nickel-plated PBO short-fiber reinforced aluminum matrix composite material according to claim 1, characterized in that, In step (2), the length of the PBO short-cut fiber is 1~6mm, the concentration of the concentrated sulfuric acid used for the roughening treatment is 70~80%, and the soaking time is 20~40s.

3. The method for preparing a nickel-plated PBO short-fiber reinforced aluminum matrix composite material according to claim 1, characterized in that, In step (3), Ni in the nickel plating solution 2+ The concentrations of sodium sulfate, sodium citrate, sodium hypophosphite, sodium pyrophosphate, and nickel plating solution are 0.03–0.06 mol / L, 0.02–0.05 mol / L, 0.10–0.16 mol / L, and 0.15–0.25 mol / L, respectively. The pH of the nickel plating solution is 10–12.

4. The method for preparing a nickel-plated PBO short-fiber reinforced aluminum matrix composite material according to claim 1, characterized in that, In step (4), the sodium hypophosphite concentration is 15~30g / L, the nickel plating temperature is 60~80℃, and the nickel plating reaction time is 80~120min.

5. The method for preparing a nickel-plated PBO short-fiber reinforced aluminum matrix composite material according to claim 1, characterized in that, In step (5), the aluminum powder particle size is 20~200μm, the nickel-plated PBO short fiber mass fraction is 3~7wt%, and the ball-to-material ratio is 3~6∶1.

6. The method for preparing a nickel-plated PBO short-fiber reinforced aluminum matrix composite material according to claim 1, characterized in that, In step (6), the ball milling speed is 200~400 r / min and the ball milling time is 3~5 h.

7. The method for preparing a nickel-plated PBO chopped fiber reinforced aluminum matrix composite material according to claim 1, characterized in that, In step (7), the discharge plasma sintering temperature is 475~575℃, the sintering pressure is 150~250MPa, and the holding time is 15~30min.

8. The method for preparing a nickel-plated PBO chopped fiber reinforced aluminum matrix composite material according to claim 1, characterized in that, In step (8), the high-temperature annealing temperature is 350~450℃, and the annealing holding time is 2~3h.

9. A nickel-plated PBO chopped fiber reinforced aluminum matrix composite material prepared by the method according to any one of claims 1-8.