CN104087773B - A kind of preparation method of nanocrystalline aluminium - Google Patents

A kind of preparation method of nanocrystalline aluminium Download PDF

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CN104087773B
CN104087773B CN201410320473.XA CN201410320473A CN104087773B CN 104087773 B CN104087773 B CN 104087773B CN 201410320473 A CN201410320473 A CN 201410320473A CN 104087773 B CN104087773 B CN 104087773B
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temperature
mould
aluminium
sintering
aluminum block
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CN104087773A (en
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张朝晖
王富耻
刘振锋
孙永君
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Beijing Institute of Technology BIT
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Beijing Institute of Technology BIT
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Abstract

The present invention relates to a kind of preparation method of nanocrystalline aluminium, belong to field of nanometer material technology.Described method is as follows: the nanometer aluminium powder coated through organic polymer is placed in the mould being lined with graphite paper, discharge plasma sintering is utilized to sinter, sintering temperature is 400 ~ 550 DEG C, vacuum tightness < 5Pa, original pressure < 5MPa, sintering pressure >=300MPa, temperature rise rate is 40 ~ 80 DEG C/min, heat-insulation pressure keeping 3 ~ 9min, after insulation terminates, cooling also release; Treat that die temperature is 95 ~ 105 DEG C, take out mold cools down to room temperature, nano aluminum block materials is taken out from mould, removes surperficial graphite paper; Last in 150 ~ 250 DEG C of vacuum heat treatment 0.5 ~ 1.5h, cool to room temperature with the furnace, obtain described nanocrystalline aluminium.The obtained nanocrystalline aluminium density of described method is high, good mechanical performance, manufacturing process simple and be easy to realize.

Description

A kind of preparation method of nanocrystalline aluminium
Technical field
The present invention relates to a kind of preparation method of nanocrystalline aluminium, belong to field of nanometer material technology.
Background technology
Al and Alalloy is good owing to having plasticity, and the features such as density is little are widely used in national product.But, be restricted because low intensity and hardness make it further apply.Nano material is owing to having tiny and even, the feature such as grain surface is clean of high density crystal boundary, grain-size, and thus its mechanical property has many advantages compared with conventional coarse grain material, as low elastic modulus, and high rigidity and high strength.Therefore, the grain-size of fine aluminium being reduced to nanoscale is the important channel of breaking this restriction.
The common method preparing nano aluminum block materials has: sever Plastic Deformation, inert gases agglomeration original position extrusion forming method, high energy mechanical polishing etc.Sever Plastic Deformation is high to equipment requirements, and is difficult to obtain the material of below 100nm due to recrystallize.All inevitably there is a large amount of hole in the standby nano block of the molded legal system of inert gases agglomeration add in-place.High energy mechanical polishing generally adopts the powder process of low temperature ball milling, nanometer aluminium powder belongs to metastable material, there is very high chemically reactive, inevitably with the Contact of the external substances such as abrading-ball, cause the pollution of nanometer aluminium powder, nanometer aluminium powder very easily occurs reunite and grow up at normal temperatures simultaneously, and these are all by the quality of nanometer aluminium block obtained for impact.
Powder metallurgic method is that nano powder is compacted into entity, is then put in hot pressing furnace and sinters.Due to the great specific surface area of nano-powder and high surfactivity, nearly the conventional sintering process of a few hours will cause grain growth, very difficult acquisition nano bulk material truly.Consider from grain growth kinetics angle, require that sintering process is sintering under the constant prerequisite of intensity of activation, shorten sintering time as far as possible, because discharge plasma sintering (SPS) technology has the technical superiority of the uniquenesses such as heat up and rate of temperature fall is fast, sintering temperature is low, soaking time is short, can ensure that nano aluminum powder reaches densification rapidly and do not cause obvious grain growth, this provides an effective approach for preparing block nanometer aluminium.
Summary of the invention
Low for present nano aluminum block materials intensity, preparation method is complicated and be difficult to prepare the defect of large size, high purity block materials, the object of the present invention is to provide a kind of preparation method of nanocrystalline aluminium, the obtained nanocrystalline aluminium density of described method is high, good mechanical performance, manufacturing process simple and be easy to realize.
Object of the present invention is realized by following technical scheme.
A preparation method for nanocrystalline aluminium, described method steps is as follows:
Step one, the nanometer aluminium powder through Coated with Organic Matter is placed in mould, the conveniently demoulding, described nanometer aluminium powder and mould inner wall and pressure head contact position need to pad graphite paper, then discharge plasma sintering is utilized to sinter, sintering temperature is 400 DEG C ~ 550 DEG C, vacuum tightness < 5Pa, original pressure < 5MPa, sintering pressure >=300MPa, temperature rise rate is 40 DEG C/min ~ 80 DEG C/min, reach heat-insulation pressure keeping 3min ~ 9min after sintering temperature, obtain nano aluminum block materials;
Wherein, described organism is polymkeric substance, is preferably polystyrene;
The particle diameter of the nanometer aluminium powder of described Coated with Organic Matter is 50nm ~ 60nm, and wherein, the thickness of Coated with Organic Matter layer is 2nm ~ 5nm;
Described moulding stock is refractory steel, is preferably molybdenum-vanadium hotwork alloy tool steel;
Described sintering temperature is preferably 500 DEG C, and temperature rise rate is preferably 60 DEG C/min, preferred heat-insulation pressure keeping 6min after reaching sintering temperature.
After step 2, insulation terminate, the pressure be applied on nano aluminum block materials is shed, in order to avoid cause the stress rupture of nano aluminum block materials in temperature-fall period when lowering the temperature and starting; Treat that the temperature of mould is reduced to 95 DEG C ~ 105 DEG C, take out mould, continue to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, remove the graphite paper that nano aluminum block materials surface adheres to.
Step 3, the nano aluminum block materials through step 2 process is carried out vacuum heat treatment, thermal treatment temp is 150 DEG C ~ 250 DEG C, and soaking time is 0.5h ~ 1.5h, in order to prevent described nano aluminum block materials oxidized, cool to room temperature with the furnace, obtain a kind of nanocrystalline aluminium;
Wherein, thermal treatment temp is preferably 200 DEG C, and soaking time is preferably 1h.
Beneficial effect
1. the invention provides a kind of preparation method of nanocrystalline aluminium, described nanocrystalline aluminium has the advantages that hardness is large and intensity is high, the most high energy of microhardness reaches 3.06GPa, the maximum 691MPa that can reach of ultimate compression strength, can solve hardness that current nano aluminum material faces and the lower problem of strength ratio;
2. the invention provides a kind of preparation method of nanocrystalline aluminium, described method is simply controlled, and concrete advantage is as follows: the method 1. adopting organic coating nanometer aluminium powder, prevents nanometer aluminium powder from contacting with air, to avoid by air and other impurity pollute, ensure that the purity of nanometer aluminium powder; Prevent the reunion between particle, improve the stability of nanometer disperse system, define a potential barrier simultaneously, their particles in synthesis and sintering process are not easily grown up; 2. the growth of grain-size is significantly reduced, the advantages such as the fast and sintering temperature of the heat-up rate of discharge plasma sintering is low are utilized to ensure that crystal grain remains on nano-scale, in sintering process, the organism degradable on aluminium powder surface is gas and is evacuated to the external world, ensure that the purity of nanocrystalline aluminium.
Accompanying drawing explanation
Fig. 1 is the scanning electron microscope (SEM) photograph of nanocrystalline aluminium prepared by embodiment 1.
Fig. 2 is the scanning electron microscope (SEM) photograph of nanocrystalline aluminium prepared by embodiment 2.
Fig. 3 is the transmission electron microscope picture of nanocrystalline aluminium prepared by embodiment 3.
Fig. 4 is the scanning electron microscope (SEM) photograph of nanocrystalline aluminium prepared by embodiment 4.
Embodiment
In order to understand the present invention better, illustrate content of the present invention further below in conjunction with embodiment, but content of the present invention is not only confined to the following examples.
In following examples:
Aluminium powder used is the nanometer aluminium powder coated through polystyrene that Shanghai Chao Wei nanosecond science and technology company limited produces, and its trade mark is CW-Al-001; In discharge plasma sintering, mould material therefor is molybdenum-vanadium hotwork alloy tool steel; The GR.TF60/11 type electron tubes type resistance furnace that vacuum heat treatment equipment selects Shanghai Gui Er mechanical means company limited to produce.
The VMHT30M type microhardness tester that micro-hardness testing is produced in Leco Corporation of the U.S. carry out; The experiment of room temperature quasistatic compression is carried out on the CMT5505 type universal testing machine of Mei Tesi industrial system (China) company limited production; The S-4800N type scanning electronic microscope that microstructure observation selects HIT to produce and the F20 transmission electron microscope that FEI Co. of the U.S. produces; The theoretical density of aluminium gets 2.7g/cm3.
Embodiment 1
A preparation method for nanocrystalline aluminium, described method steps is as follows:
Step one, the nanometer aluminium powder coated through polystyrene is placed in mould, the conveniently demoulding, the place that nanometer aluminium powder contacts with mould inner wall and pressure head is lined with one deck graphite paper; Then utilize discharge plasma sintering to sinter, sintering temperature is 400 DEG C, and vacuum tightness is 4Pa, and original pressure is 4MPa, and sintering pressure is 300MPa, and temperature rise rate is 40 DEG C/min, reaches heat-insulation pressure keeping 3min after sintering temperature, obtains nano aluminum block materials;
After step 2, insulation terminate, the pressure be applied on nano aluminum block materials is shed, in order to avoid cause the stress rupture of nano aluminum block materials in temperature-fall period when lowering the temperature and starting; Treat that the temperature of mould is reduced to 100 DEG C, take out mould, continue to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, with sand paper, the graphite paper that nano aluminum block materials surface adheres to all is removed until surface-brightening is smooth;
Step 3, the nano aluminum block materials obtained through step 2 process is carried out vacuum heat treatment, thermal treatment temp is 150 DEG C, and soaking time is 0.5h, in order to prevent described nano aluminum block materials oxidized, cool to room temperature with the furnace, then take out, obtain a kind of nanocrystalline aluminium.
Performance test is carried out to the nanocrystalline aluminium that the present embodiment obtains: the relative density utilizing Archimedes's drainage to record nanocrystalline aluminium is 96%, micro-hardness testing, the experiment of room temperature quasistatic compression and microstructure observation have been carried out to nanocrystalline aluminium, microhardness is 1.23GPa, ultimate compression strength is 576MPa, scanning electron microscopic picture as shown in Figure 1, uniform small grains as we can see from the figure, grain-size is at about 70nm, nanocrystalline aluminium inside does not have hole substantially, and good bonding strength between particle is described.
Embodiment 2
A preparation method for nanocrystalline aluminium, described method steps is as follows:
Step one, the nanometer aluminium powder coated through polystyrene is placed in mould, the conveniently demoulding, the place that nanometer aluminium powder contacts with mould inner wall and pressure head is lined with one deck graphite paper; Then utilize discharge plasma sintering to sinter, sintering temperature is 500 DEG C, and vacuum tightness is 3Pa, and original pressure is 3MPa, and sintering pressure is 350MPa, and temperature rise rate is 60 DEG C/min, reaches heat-insulation pressure keeping 6min after sintering temperature, obtains nano aluminum block materials;
After step 2, insulation terminate, the pressure be applied on nano aluminum block materials is shed, in order to avoid cause the stress rupture of nano aluminum block materials in temperature-fall period when lowering the temperature and starting; Treat that the temperature of mould is reduced to 100 DEG C, take out mould, continue to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, with sand paper, the graphite paper that nano aluminum block materials surface adheres to all is removed until surface-brightening is smooth;
Step 3, the nano aluminum block materials obtained through step 2 process is carried out vacuum heat treatment, thermal treatment temp is 200 DEG C, and soaking time is 1.5h, in order to prevent described nano aluminum block materials oxidized, cool to room temperature with the furnace, then take out, obtain a kind of nanocrystalline aluminium.
Performance test is carried out to the nanocrystalline aluminium that the present embodiment obtains: the relative density utilizing Archimedes's drainage to record nanocrystalline aluminium is 99.5%, micro-hardness testing, the experiment of room temperature quasistatic compression have been carried out to nanocrystalline aluminium, microhardness is 3.06GPa, and ultimate compression strength is 691MPa; Carry out microstructure observation, its scanning electron microscopic picture is shown in Fig. 2, can find out that described nanocrystalline aluminium inside does not have hole substantially, good bonding strength between particle is described; Uniform small grains, size is at about 75nm.
Embodiment 3
A preparation method for nanocrystalline aluminium, described method steps is as follows:
Step one, the nanometer aluminium powder coated through polystyrene is placed in mould, the conveniently demoulding, the place that nanometer aluminium powder contacts with mould inner wall and pressure head is lined with one deck graphite paper; Then utilize discharge plasma sintering to sinter, sintering temperature is 500 DEG C, and vacuum tightness is 4Pa, and original pressure is 1MPa, and sintering pressure is 400MPa, and temperature rise rate is 80 DEG C/min, reaches heat-insulation pressure keeping 9min after sintering temperature, obtains nano aluminum block materials;
After step 2, insulation terminate, the pressure be applied on nano aluminum block materials is shed, in order to avoid cause the stress rupture of nano aluminum block materials in temperature-fall period when lowering the temperature and starting; Treat that the temperature of mould is reduced to 100 DEG C, take out mould, continue to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, with sand paper, the graphite paper that nano aluminum block materials surface adheres to all is removed until surface-brightening is smooth;
Step 3, the nano aluminum block materials obtained through step 2 process is carried out vacuum heat treatment, thermal treatment temp is 250 DEG C, and soaking time is 1h, in order to prevent described nano aluminum block materials oxidized, cool to room temperature with the furnace, then take out, obtain a kind of nanocrystalline aluminium.
Performance test is carried out to the nanocrystalline aluminium that the present embodiment obtains: the relative density utilizing Archimedes's drainage to record nanocrystalline aluminium is 99.5%, micro-hardness testing, the experiment of room temperature quasistatic compression have been carried out to nanocrystalline aluminium, microhardness is 2.98GPa, and ultimate compression strength is 676MPa; To carrying out transmission electron microscope observing, as shown in Figure 3, can find out that the inside of described nanocrystalline aluminium does not have hole substantially, good bonding strength between particle is described, uniform particles distributes, and the shaft-like such as be, grain-size is at about 80nm.
Embodiment 4
A preparation method for nanocrystalline aluminium, described method steps is as follows:
Step one, the nanometer aluminium powder coated through polystyrene is placed in mould, the conveniently demoulding, the place that nanometer aluminium powder contacts with mould inner wall and pressure head is lined with one deck graphite paper; Then utilize discharge plasma sintering to sinter, sintering temperature is 550 DEG C, and vacuum tightness is 3Pa, and original pressure is 1MPa, and sintering pressure is 300MPa, and temperature rise rate is 40 DEG C/min, reaches heat-insulation pressure keeping 6min after sintering temperature, obtains nano aluminum block materials;
After step 2, insulation terminate, the pressure be applied on nano aluminum block materials is shed, in order to avoid cause the stress rupture of nano aluminum block materials in temperature-fall period when lowering the temperature and starting; Treat that the temperature of mould is reduced to 100 DEG C, take out mould, continue to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, with sand paper, the graphite paper that nano aluminum block materials surface adheres to all is removed until surface-brightening is smooth;
Step 3, the nano aluminum block materials obtained through step 2 process is carried out vacuum heat treatment, thermal treatment temp is 150 DEG C, and soaking time is 1h, in order to prevent described nano aluminum block materials oxidized, cool to room temperature with the furnace, then take out, obtain a kind of nanocrystalline aluminium.
Performance test is carried out to the nanocrystalline aluminium that the present embodiment obtains: the relative density utilizing Archimedes's drainage to record nanocrystalline aluminium is 99.8%, micro-hardness testing, the experiment of room temperature quasistatic compression have been carried out to nanocrystalline aluminium, microhardness is 1.4GPa, and ultimate compression strength is 221MPa; Carry out microstructure observation to sample, see Fig. 4, sample inside does not have hole substantially as seen from the figure, and good bonding strength between particle is described.Obviously grow up although particle has, intensity is still far away higher than common coarse-grain aluminium, and grain-size is at about 200nm.
The present invention includes but be not limited to above embodiment, every any equivalent replacement of carrying out under the principle of spirit of the present invention or local improvement, all will be considered as within protection scope of the present invention.

Claims (4)

1. a preparation method for nanocrystalline aluminium, is characterized in that: step is as follows:
Step one, the nanometer aluminium powder through Coated with Organic Matter is placed in mould, nanometer aluminium powder and mould inner wall and pressure head contact position pad graphite paper, then discharge plasma sintering is utilized to sinter, sintering temperature is 400 DEG C ~ 550 DEG C, vacuum tightness < 5Pa, original pressure < 5MPa, sintering pressure >=300MPa, temperature rise rate is 40 DEG C/min ~ 80 DEG C/min, and reach heat-insulation pressure keeping 3min ~ 9min after sintering temperature, obtain nano aluminum block materials;
Organism is polystyrene;
The particle diameter of the nanometer aluminium powder of Coated with Organic Matter is 50nm ~ 60nm, and the thickness of Coated with Organic Matter layer is 2nm ~ 5nm;
Moulding stock is refractory steel;
After step 2, insulation terminate, when lowering the temperature and starting, the pressure be applied on nano aluminum block materials is shed; Treat that the temperature of mould is reduced to 95 DEG C ~ 105 DEG C, take out mould and continue to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, remove the graphite paper that nano aluminum block materials surface adheres to;
Step 3, the nano aluminum block materials through step 2 process is carried out vacuum heat treatment, thermal treatment temp is 150 DEG C ~ 250 DEG C, and soaking time is 0.5h ~ 1.5h, cools to room temperature with the furnace, obtains a kind of nanocrystalline aluminium.
2. the preparation method of a kind of nanocrystalline aluminium according to claim 1, is characterized in that: the moulding stock in step one is molybdenum-vanadium hotwork alloy tool steel.
3. the preparation method of a kind of nanocrystalline aluminium according to claim 1, is characterized in that: the sintering temperature in step one is 500 DEG C, and temperature rise rate is 60 DEG C/min, reaches heat-insulation pressure keeping 6min after sintering temperature.
4. the preparation method of a kind of nanocrystalline aluminium according to claim 1, it is characterized in that: the thermal treatment temp in step 3 is 200 DEG C, soaking time is 1h.
CN201410320473.XA 2014-07-07 2014-07-07 A kind of preparation method of nanocrystalline aluminium Expired - Fee Related CN104087773B (en)

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