CN104087773A - Preparation method of nanocrystalline aluminum - Google Patents
Preparation method of nanocrystalline aluminum Download PDFInfo
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- CN104087773A CN104087773A CN201410320473.XA CN201410320473A CN104087773A CN 104087773 A CN104087773 A CN 104087773A CN 201410320473 A CN201410320473 A CN 201410320473A CN 104087773 A CN104087773 A CN 104087773A
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Abstract
The invention relates to a preparation method of nanocrystalline aluminum, and belongs to the field of nanomaterials. The method comprises the following steps: sintering nano aluminum powder coated with an organic polymer in a mould lined with graphite paper by virtue of discharge plasmas under the conditions that the sintering temperature is 400-550 DEG C, the vacuum degree is less than 5Pa, the initial pressure is less than 5MPa, the sintering pressure is not less than 300MPa and the heating rate is 40-80 DEG C/min, keeping the temperature and the pressure for 3-9 minutes, after heat preservation is finished, cooling and performing pressure relief; when the temperature of the mould is 95-105 DEG C, taking out the mould, cooling to room temperature, taking out a nano aluminum block material from the mould, and removing the graphite paper from the surface of the mould; finally performing vacuum heat treatment at 150-250 DEG C for 0.5-1.5 hours, and performing furnace cooling to room temperature to obtain nanocrystalline aluminum. Nanocrystalline aluminum prepared by adopting the method is high in density, excellent in mechanical property and easy to form and realize.
Description
Technical field
The preparation method who the present invention relates to a kind of nanocrystalline aluminium, belongs to field of nanometer material technology.
Background technology
The features such as aluminium and aluminium alloy are good owing to having plasticity, and density is little are widely used in national product.But, due to low intensity and hardness make its further application be restricted.The nano material features such as high density crystal boundary, grain-size are tiny and even owing to having, grain surface is clean, thereby its mechanical property has many advantages compared with conventional coarse grain material, as low elastic modulus, 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 of 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 because recrystallize is difficult to obtain the material below 100nm.All inevitably there are a large amount of holes 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 can and the external substance such as abrading-ball between contact, cause the pollution of nanometer aluminium powder, nanometer aluminium powder very easily occurs to reunite and grows up at normal temperatures simultaneously, the quality of the nanometer aluminium block that these all make impact.
Powder metallurgic method is that nano powder is compacted into entity, is then put into sintering in hot pressing furnace.Due to the great specific surface area of nano-powder and high surfactivity, nearly the normal sintering method of a few hours will cause grain growth, very difficult acquisition nano bulk material truly.Consider from grain growth kinetics angle, require sintering process under the constant prerequisite of sintering intensity of activation, shorten sintering time as far as possible, because discharge plasma sintering (SPS) technology has unique technical superioritys such as heat up and rate of temperature fall is fast, sintering temperature is low, soaking time is short, can ensure nano aluminum powder to reach densification rapidly and 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, nanocrystalline aluminium density that described method makes is high, good mechanical performance, manufacturing process is 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 1, will be placed in mould through the nanometer aluminium powder of Coated with Organic Matter, for conveniently stripped, graphite paper need to be padded in described nanometer aluminium powder and mould inner wall and pressure head contact position, then utilize discharge plasma sintering to carry out sintering, 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, reaches after sintering temperature preferably heat-insulation pressure keeping 6min.
After step 2, insulation finish, in the time that cooling starts, the pressure being 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; The temperature for the treatment of mould is reduced to 95 DEG C～105 DEG C, takes out mould, continues to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, removes the graphite paper that nano aluminum block materials surface adheres to.
Step 3, will carry out vacuum heat treatment through the nano aluminum block materials of step 2 processing, thermal treatment temp is 150 DEG C～250 DEG C, and soaking time is 0.5h～1.5h, oxidized in order to prevent described nano aluminum block materials, 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 hardness greatly and the high feature of intensity, the high energy of microhardness reaches 3.06GPa, and ultimate compression strength maximum can reach 691MPa, can solve hardness and the lower problem of strength ratio that current nano aluminum material faces;
2. the invention provides a kind of preparation method of nanocrystalline aluminium, described method is simply controlled, and concrete advantage is as follows: 1. adopt the method for organic coating nanometer aluminium powder, prevent that nanometer aluminium powder from contacting with air, avoid being polluted by air and other impurity, guaranteed the purity of nanometer aluminium powder; Prevent the reunion between particle, improved the stability of nanometer disperse system, formed a potential barrier simultaneously, make their particles in synthetic and sintering process be difficult for growing up; 2. greatly reduced the growth of grain-size, utilize the advantages such as the heat-up rate of discharge plasma sintering is fast and sintering temperature is low 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, has ensured the purity of nanocrystalline aluminium.
Brief description of the drawings
Fig. 1 is the scanning electron microscope (SEM) photograph of the nanocrystalline aluminium prepared of embodiment 1.
Fig. 2 is the scanning electron microscope (SEM) photograph of the nanocrystalline aluminium prepared of embodiment 2.
Fig. 3 is the transmission electron microscope picture of the nanocrystalline aluminium prepared of embodiment 3.
Fig. 4 is the scanning electron microscope (SEM) photograph of the nanocrystalline aluminium prepared of embodiment 4.
Embodiment
In order to understand better the present invention, further illustrate content of the present invention 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 coated nanometer aluminium powder of process 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.
On the VMHT30M type microhardness tester that micro-hardness testing is produced in Leco Corporation of the U.S., carry out; On the CMT5505 type universal testing machine that room temperature quasistatic compression experiment is produced in Mei Tesi industrial system (China) company limited, carry out; Microstructure observation selects the S-4800N type scanning electronic microscope of HIT's production and the F20 transmission electron microscope that FEI Co. of the U.S. produces; The theoretical density of aluminium is got 2.7g/cm3.
Embodiment 1
A preparation method for nanocrystalline aluminium, described method steps is as follows:
Step 1, will be placed in mould through polystyrene coated nanometer aluminium powder, for conveniently stripped, 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 carry out sintering, 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 finish, in the time that cooling starts, the pressure being 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; The temperature for the treatment of mould is reduced to 100 DEG C, takes out mould, continues to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, and graphite paper nano aluminum block materials surface being adhered to sand paper is all removed until surface-brightening is smooth;
Step 3, the nano aluminum block materials that the processing of process step 2 is obtained carry out vacuum heat treatment, and thermal treatment temp is 150 DEG C, and soaking time is 0.5h, oxidized in order to prevent described nano aluminum block materials, cool to room temperature with the furnace, then take out, obtain a kind of nanocrystalline aluminium.
The nanocrystalline aluminium that the present embodiment is obtained carries out performance test: the relative density that utilizes Archimedes's drainage to record nanocrystalline aluminium is 96%, nanocrystalline aluminium has been carried out to micro-hardness testing, room temperature quasistatic compression experiment and microstructure observation, microhardness is 1.23GPa, ultimate compression strength is 576MPa, scanning electron microscope picture as shown in Figure 1, crystal grain is tiny evenly as we can see from the figure, grain-size is in 70nm left and right, 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 1, will be placed in mould through polystyrene coated nanometer aluminium powder, for conveniently stripped, 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 carry out sintering, 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 finish, in the time that cooling starts, the pressure being 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; The temperature for the treatment of mould is reduced to 100 DEG C, takes out mould, continues to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, and graphite paper nano aluminum block materials surface being adhered to sand paper is all removed until surface-brightening is smooth;
Step 3, the nano aluminum block materials that the processing of process step 2 is obtained carry out vacuum heat treatment, and thermal treatment temp is 200 DEG C, and soaking time is 1.5h, oxidized in order to prevent described nano aluminum block materials, cool to room temperature with the furnace, then take out, obtain a kind of nanocrystalline aluminium.
The nanocrystalline aluminium that the present embodiment is obtained carries out performance test: the relative density that utilizes Archimedes's drainage to record nanocrystalline aluminium is 99.5%, nanocrystalline aluminium has been carried out to micro-hardness testing, room temperature quasistatic compression experiment, microhardness is 3.06GPa, and ultimate compression strength is 691MPa; Carry out microstructure observation, Fig. 2 is shown in by its scanning electron microscope picture, can find out that described nanocrystalline aluminium inside does not have hole substantially, illustrates good bonding strength between particle; Crystal grain is tiny evenly, and size is in 75nm left and right.
Embodiment 3
A preparation method for nanocrystalline aluminium, described method steps is as follows:
Step 1, will be placed in mould through polystyrene coated nanometer aluminium powder, for conveniently stripped, 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 carry out sintering, 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 finish, in the time that cooling starts, the pressure being 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; The temperature for the treatment of mould is reduced to 100 DEG C, takes out mould, continues to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, and graphite paper nano aluminum block materials surface being adhered to sand paper is all removed until surface-brightening is smooth;
Step 3, the nano aluminum block materials that the processing of process step 2 is obtained carry out vacuum heat treatment, and thermal treatment temp is 250 DEG C, and soaking time is 1h, oxidized in order to prevent described nano aluminum block materials, cool to room temperature with the furnace, then take out, obtain a kind of nanocrystalline aluminium.
The nanocrystalline aluminium that the present embodiment is obtained carries out performance test: the relative density that utilizes Archimedes's drainage to record nanocrystalline aluminium is 99.5%, nanocrystalline aluminium has been carried out to micro-hardness testing, room temperature quasistatic compression experiment, 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 is and waits axle shape, and grain-size is about the 80nm.
Embodiment 4
A preparation method for nanocrystalline aluminium, described method steps is as follows:
Step 1, will be placed in mould through polystyrene coated nanometer aluminium powder, for conveniently stripped, 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 carry out sintering, 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 finish, in the time that cooling starts, the pressure being 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; The temperature for the treatment of mould is reduced to 100 DEG C, takes out mould, continues to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, and graphite paper nano aluminum block materials surface being adhered to sand paper is all removed until surface-brightening is smooth;
Step 3, the nano aluminum block materials that the processing of process step 2 is obtained carry out vacuum heat treatment, and thermal treatment temp is 150 DEG C, and soaking time is 1h, oxidized in order to prevent described nano aluminum block materials, cool to room temperature with the furnace, then take out, obtain a kind of nanocrystalline aluminium.
The nanocrystalline aluminium that the present embodiment is obtained carries out performance test: the relative density that utilizes Archimedes's drainage to record nanocrystalline aluminium is 99.8%, nanocrystalline aluminium has been carried out to micro-hardness testing, room temperature quasistatic compression experiment, microhardness is 1.4GPa, and ultimate compression strength is 221MPa; Sample is carried out to microstructure observation, see Fig. 4, sample inside does not have hole substantially as seen from the figure, and good bonding strength between particle is described.Grow up although particle has obviously, intensity is still far away higher than common coarse-grain aluminium, and grain-size is in 200nm left and right.
The present invention includes but be not limited to above embodiment, every any being equal to of carrying out under the principle of spirit of the present invention, replaces or local improvement, all will be considered as within protection scope of the present invention.
Claims (5)
1. a preparation method for nanocrystalline aluminium, is characterized in that: step is as follows:
Step 1, will be placed in mould through the nanometer aluminium powder of Coated with Organic Matter, nanometer aluminium powder and mould inner wall and pressure head contact position pad graphite paper, then utilize discharge plasma sintering to carry out sintering, 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, reaches heat-insulation pressure keeping 3min～9min after sintering temperature, obtains nano aluminum block materials;
Organism is polymkeric substance;
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 finish, in the time that cooling starts, the pressure being applied on nano aluminum block materials is shed; The temperature for the treatment of mould is reduced to 95 DEG C～105 DEG C, takes out mould and continues to be cooled to room temperature, subsequently nano aluminum block materials is taken out from mould, removes the graphite paper that nano aluminum block materials surface adheres to;
Step 3, will carry out vacuum heat treatment through the nano aluminum block materials of step 2 processing, 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 organism in step 1 is polystyrene.
3. the preparation method of a kind of nanocrystalline aluminium according to claim 1, is characterized in that: the moulding stock in step 1 is molybdenum-vanadium hotwork alloy tool steel.
4. the preparation method of a kind of nanocrystalline aluminium according to claim 1, is characterized in that: the sintering temperature in step 1 is 500 DEG C, and temperature rise rate is 60 DEG C/min, reaches heat-insulation pressure keeping 6min after sintering temperature.
5. the preparation method of a kind of nanocrystalline aluminium according to claim 1, is characterized in that: the thermal treatment temp in step 3 is 200 DEG C, and soaking time is 1h.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106001560A (en) * | 2016-05-25 | 2016-10-12 | 北京理工大学 | Preparation method for nanocrystalline silver bar |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2004292864A (en) * | 2003-03-26 | 2004-10-21 | Kurimoto Ltd | Heat treatment method for aluminum composite material |
| CN1966736A (en) * | 2005-11-16 | 2007-05-23 | 中国科学院金属研究所 | Process for preparing nano-crystalline aluminium materials |
| CN102618807A (en) * | 2011-12-29 | 2012-08-01 | 北京理工大学 | Aluminum-based amorphous/nanocrystalline composite material and preparation method thereof |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004292864A (en) * | 2003-03-26 | 2004-10-21 | Kurimoto Ltd | Heat treatment method for aluminum composite material |
| CN1966736A (en) * | 2005-11-16 | 2007-05-23 | 中国科学院金属研究所 | Process for preparing nano-crystalline aluminium materials |
| CN102618807A (en) * | 2011-12-29 | 2012-08-01 | 北京理工大学 | Aluminum-based amorphous/nanocrystalline composite material and preparation method thereof |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106001560A (en) * | 2016-05-25 | 2016-10-12 | 北京理工大学 | Preparation method for nanocrystalline silver bar |
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