阅读说明：本技术 一种纳米碳铝复合导热材料及其在制备高功率led光源散热器中的应用 (Nano carbon-aluminum composite heat conduction material and application thereof in preparation of high-power LED light source radiator ) 是由 张鹏 林志丹 李卫 曹琳 于 2021-06-10 设计创作，主要内容包括：本发明公开了一种纳米碳铝复合导热材料及其在制备高功率LED光源散热器中的应用。所述的纳米碳铝复合导热材料,其包含如下重量份的原料：铝70～100份；硅1～3份；铁0.5～2份；锌0.1～1份；锶0.1-1份；铜0.01～0.1份；碳纳米管0.1～1份；钛酸铋或改性钛酸铋15～30份。由于本发明所述的纳米碳铝复合导热材料具有较低的热膨胀系数以及较高的导热率,因此,将其应用于制备高功率LED光源散热器,可以提高高功率LED光源散热器的散热效率以及减少高功率LED光源散热器在温差较大的环境下使用发生变形的情况。(The invention discloses a nano carbon-aluminum composite heat conduction material and application thereof in preparation of a high-power LED light source radiator. The nano carbon-aluminum composite heat conduction material comprises the following raw materials in parts by weight: 70-100 parts of aluminum; 1-3 parts of silicon; 0.5-2 parts of iron; 0.1-1 part of zinc; 0.1-1 part of strontium; 0.01-0.1 part of copper; 0.1-1 part of carbon nano tube; 15-30 parts of bismuth titanate or modified bismuth titanate. The nano carbon-aluminum composite heat conduction material has lower thermal expansion coefficient and higher heat conductivity, so that the nano carbon-aluminum composite heat conduction material is applied to the preparation of the high-power LED light source radiator, the heat dissipation efficiency of the high-power LED light source radiator can be improved, and the deformation of the high-power LED light source radiator in the environment with larger temperature difference can be reduced.)

1. The nano carbon-aluminum composite heat conduction material is characterized by comprising the following raw materials in parts by weight:

70-100 parts of aluminum; 1-3 parts of silicon; 0.5-2 parts of iron; 0.1-1 part of zinc; 0.1-1 part of strontium; 0.01-0.1 part of copper; 0.1-1 part of carbon nano tube; 15-30 parts of bismuth titanate or modified bismuth titanate.

2. The nanocarbon aluminum composite heat conduction material according to claim 1, characterized by comprising the following raw materials in parts by weight:

80-90 parts of aluminum; 2-3 parts of silicon; 1-2 parts of iron; 0.1-0.5 part of zinc; 0.1-0.5 part of strontium; 0.05-0.1 part of copper; 0.1-0.5 parts of carbon nano tubes; 20-30 parts of bismuth titanate or modified bismuth titanate.

3. The nanocarbon aluminum composite heat conduction material according to claim 1, characterized by comprising the following raw materials in parts by weight:

80 parts of aluminum; 2 parts of silicon; 1 part of iron; 0.3 part of zinc; 0.2 part of strontium; 0.08 part of copper; 0.5 part of carbon nano tube; 20 parts of bismuth titanate or modified bismuth titanate.

4. The nanocarbon aluminum composite heat conductive material of claim 1, wherein the carbon nanotubes are single-walled carbon nanotubes or multi-walled carbon nanotubes.

5. The nanocarbon aluminum composite heat conductive material according to claim 1, wherein the modified bismuth titanate is prepared by a method comprising the following steps:

mixing 50-70 parts by weight of bismuth titanate, 10-30 parts by weight of lanthanum oxide and 10-30 parts by weight of niobium pentoxide, and then carrying out ball milling to obtain ball-milled powder 1;

presintering the ball-milled powder 1 at 870-900 ℃ for 20-40 min; obtaining a pre-sintering mixture;

ball-milling the pre-sintered mixture to obtain ball-milled powder 2; the obtained ball milling powder 2 is the modified bismuth titanate.

6. The nanocarbon aluminum composite heat conduction material according to claim 5, characterized in that 60-70 parts by weight of bismuth titanate, 20-30 parts by weight of lanthanum oxide and 20-30 parts by weight of niobium pentoxide are mixed and then ball-milled to obtain ball-milled powder 1.

7. The nanocarbon aluminum composite heat conduction material according to claim 5, wherein ball-milled powder is presintered at 870 ℃ for 30 min; and (5) obtaining a pre-sintering mixture.

8. The nanocarbon aluminum composite heat conductive material according to claim 5, wherein the ball milling is performed in a ball mill.

9. The preparation method of the nanocarbon aluminum composite heat conduction material according to any one of claims 1 to 8, characterized by comprising the following steps:

melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding carbon nano tubes and bismuth titanate or modified bismuth titanate, uniformly stirring to obtain alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

10. The application of the nanocarbon aluminum composite heat conduction material as claimed in any one of claims 1 to 8 in preparation of a high-power LED light source radiator.

Technical Field

The invention relates to the technical field of aluminum alloy preparation, in particular to a nano carbon-aluminum composite heat conduction material and application thereof in preparation of a high-power LED light source radiator.

Background

The aluminum alloy is prepared by adding a certain amount of other alloying elements into aluminum as a base; it has high strength, electric and heat conducting performance and excellent casting performance, and thus has wide application in spaceflight, aviation, transportation, building, electromechanical and other fields.

Chinese invention patent 201611038514.1 discloses a heat-conducting aluminum alloy and application thereof, wherein the alloy elements comprise: 5.0-11.0 wt.% Si, 0.4-1.0 wt.% Fe, 0.2-1.0 wt.% Mg, less than 0.1 wt.% Zn, less than 0.1 wt.% Mn, less than 0.1 wt.% Sr, and less than 0.1 wt.% Cu. The tensile strength of the heat-conducting aluminum alloy is not lower than 250MPa, the yield strength is not lower than 150MPa, the elongation is not lower than 3.5%, and the heat conductivity is not lower than 150W/(m.K).

Chinese patent 201811532160.5 discloses a high thermal conductivity aluminum alloy, which contains the following components by weight percent: 80-90% of Al, 6.5-8.5% of Si, 0.2-0.5% of Fe, 0.8-3% of Zn, 0.03-0.05% of V, 0.01-1% of Sr and 0.02-0.08% of graphene. The high-thermal-conductivity aluminum alloy optimizes alloy elements such as Si, Fe, Zn and the like, adds elements such as Sr, V, graphene and the like, controls the content of each component, and is coordinated with each other to obtain the high-thermal-conductivity aluminum alloy with good casting performance and excellent semi-solid die-casting performance. Graphene is added into the high-thermal-conductivity aluminum alloy, and the good thermal conductivity of the graphene is applied to the aluminum alloy to obtain the high-thermal-conductivity aluminum alloy.

Thus, it can be seen that the prior art has obtained an aluminum alloy composite material having high thermal conductivity by compounding various metals and carbon materials with aluminum.

The existing aluminum alloy composite material has large thermal expansion coefficient and is easy to deform under the influence of temperature; especially, when the material is applied to an environment with large temperature difference, the material is easy to deform. Therefore, there is a need to develop an aluminum alloy pipe composite material with a small thermal expansion coefficient and a high thermal conductivity.

Disclosure of Invention

In order to overcome the technical problems that the existing heat-conducting aluminum alloy has large thermal expansion coefficient and is easy to deform under the influence of temperature, the invention provides a nano carbon-aluminum composite heat-conducting material; compared with the existing heat-conducting aluminum alloy, the nano carbon-aluminum composite heat-conducting material has smaller thermal expansion coefficient.

The technical scheme of the invention is as follows:

the invention provides a nano carbon-aluminum composite heat conduction material which comprises the following raw materials in parts by weight:

70-100 parts of aluminum; 1-3 parts of silicon; 0.5-2 parts of iron; 0.1-1 part of zinc; 0.1-1 part of strontium; 0.01-0.1 part of copper; 0.1-1 part of carbon nano tube; 15-30 parts of bismuth titanate or modified bismuth titanate.

When the nano carbon-aluminum composite heat conduction material is prepared by taking aluminum, silicon, iron, zinc, strontium and copper as raw materials, the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material can be reduced by adding bismuth titanate, and particularly, the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material can be greatly reduced by adding the modified bismuth titanate prepared by the method.

The heat conductivity of the nano carbon-aluminum composite heat conduction material is reduced along with the addition of the bismuth titanate or the modified bismuth titanate, and in order to prevent the bismuth titanate or the modified bismuth titanate from influencing the heat conductivity of the nano carbon-aluminum composite heat conduction material, a large number of experiments show that the technical problem of the reduction of the heat conductivity of the nano carbon-aluminum composite heat conduction material along with the addition of the bismuth titanate or the modified bismuth titanate can be effectively solved by adding the carbon nano tube while adding the bismuth titanate or the modified bismuth titanate.

Preferably, the nanocarbon aluminum composite heat conduction material comprises the following raw materials in parts by weight:

80-90 parts of aluminum; 2-3 parts of silicon; 1-2 parts of iron; 0.1-0.5 part of zinc; 0.1-0.5 part of strontium; 0.05-0.1 part of copper; 0.1-0.5 parts of carbon nano tubes; 20-30 parts of bismuth titanate or modified bismuth titanate.

Most preferably, the nanocarbon aluminum composite heat conduction material comprises the following raw materials in parts by weight:

80 parts of aluminum; 2 parts of silicon; 1 part of iron; 0.3 part of zinc; 0.2 part of strontium; 0.08 part of copper; 0.5 part of carbon nano tube; 20 parts of bismuth titanate or modified bismuth titanate.

Preferably, the carbon nanotubes are single-walled carbon nanotubes or multi-walled carbon nanotubes.

Preferably, the modified bismuth titanate is prepared by a method comprising the following steps:

mixing 50-70 parts by weight of bismuth titanate, 10-30 parts by weight of lanthanum oxide and 10-30 parts by weight of niobium pentoxide, and then carrying out ball milling to obtain ball-milled powder 1;

presintering the ball-milled powder 1 at 870-900 ℃ for 20-40 min; obtaining a pre-sintering mixture;

ball-milling the pre-sintered mixture to obtain ball-milled powder 2; the obtained ball milling powder 2 is the modified bismuth titanate.

Preferably, 60-70 parts by weight of bismuth titanate, 20-30 parts by weight of lanthanum oxide and 20-30 parts by weight of niobium pentoxide are mixed and then ball-milled to obtain the ball-milled powder 1.

Most preferably, 60 parts by weight of bismuth titanate, 20 parts by weight of lanthanum oxide and 20 parts by weight of niobium pentoxide are mixed and then ball-milled to obtain the ball-milled powder 1.

Preferably, presintering the ball-milled powder at 870 ℃ for 30 min; and (5) obtaining a pre-sintering mixture.

Preferably, the ball milling is performed in a ball mill.

Lanthanum oxide and niobium pentoxide are adopted to modify bismuth titanate, and compared with unmodified bismuth titanate, the prepared modified bismuth titanate can further greatly reduce the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material.

The invention also provides a preparation method of the nano carbon-aluminum composite heat conduction material, which comprises the following steps:

melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding carbon nano tubes and bismuth titanate or modified bismuth titanate, uniformly stirring to obtain alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

The invention also provides application of the nano carbon-aluminum composite heat conduction material in preparation of a high-power LED light source radiator.

Has the advantages that: the invention provides a nano carbon-aluminum composite heat conduction material with brand new composition, and researches show that the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material can be reduced by adding bismuth titanate into the preparation raw material of the nano carbon-aluminum composite heat conduction material, and particularly, the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material can be further greatly reduced by adding the modified bismuth titanate prepared by the brand new method compared with the unmodified bismuth titanate. In addition, the carbon nano tube is added while the bismuth titanate or the modified bismuth titanate is added, so that the technical problem that the heat conductivity of the nano carbon-aluminum composite heat conduction material is reduced along with the addition of the bismuth titanate or the modified bismuth titanate can be effectively solved. The nano carbon-aluminum composite heat conduction material has lower thermal expansion coefficient and higher heat conductivity, so that the nano carbon-aluminum composite heat conduction material is applied to the preparation of the high-power LED light source radiator, the heat dissipation efficiency of the high-power LED light source radiator can be improved, and the deformation of the high-power LED light source radiator in the environment with larger temperature difference can be reduced.

Detailed Description

The present invention is further explained below with reference to specific examples, which are not intended to limit the present invention in any way.

Example 1 preparation of nanocarbon aluminum composite thermal conductive material

The raw materials comprise the following components in parts by weight: 80 parts of aluminum; 2 parts of silicon; 1 part of iron; 0.3 part of zinc; 0.2 part of strontium; 0.08 part of copper; 0.5 part of single-walled carbon nanotube; and 20 parts of bismuth titanate.

The preparation method comprises the following steps: melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding single-walled carbon nanotubes and bismuth titanate, uniformly stirring to obtain an alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

Example 2 preparation of nanocarbon aluminum composite thermal conductive material

The raw materials comprise the following components in parts by weight: 80 parts of aluminum; 2 parts of silicon; 1 part of iron; 0.3 part of zinc; 0.2 part of strontium; 0.08 part of copper; 0.5 part of single-walled carbon nanotube; 20 parts of modified bismuth titanate;

the modified bismuth titanate is prepared by the following method: (1) mixing 60 parts by weight of bismuth titanate, 20 parts by weight of lanthanum oxide and 20 parts by weight of niobium pentoxide, and then putting the mixture into a ball mill for ball milling to obtain ball milling powder 1; (2) presintering the ball-milled powder 1 at 870 ℃ for 30 min; obtaining a pre-sintering mixture; (3) putting the pre-sintered mixture into a ball mill for ball milling to obtain ball milling powder 2; the obtained ball milling powder 2 is the modified bismuth titanate.

The preparation method comprises the following steps: melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding a single-walled carbon nanotube and modified bismuth titanate, uniformly stirring to obtain an alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

Example 3 preparation of nanocarbon aluminum composite thermal conductive material

The raw materials comprise the following components in parts by weight: 70 parts of aluminum; 3 parts of silicon; 2 parts of iron; 0.1 part of zinc; 0.1 part of strontium; 0.01 part of copper; 0.1 part of single-walled carbon nanotube; 15 parts of modified bismuth titanate;

the modified bismuth titanate is prepared by the following method: (1) mixing 70 parts by weight of bismuth titanate, 10 parts by weight of lanthanum oxide and 20 parts by weight of niobium pentoxide, and then putting the mixture into a ball mill for ball milling to obtain ball milling powder 1; (2) presintering the ball-milled powder 1 at 870 ℃ for 30 min; obtaining a pre-sintering mixture; (3) putting the pre-sintered mixture into a ball mill for ball milling to obtain ball milling powder 2; the obtained ball milling powder 2 is the modified bismuth titanate.

The preparation method comprises the following steps: melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding a single-walled carbon nanotube and modified bismuth titanate, uniformly stirring to obtain an alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

Example 4 preparation of nanocarbon aluminum composite thermal conductive material

The raw materials comprise the following components in parts by weight: 100 parts of aluminum; 1 part of silicon; 0.5 part of iron; 1 part of zinc; 1 part of strontium; 0.1 part of copper; 1 part of single-walled carbon nanotube; 30 parts of modified bismuth titanate;

the modified bismuth titanate is prepared by the following method: (1) mixing 50 parts by weight of bismuth titanate, 30 parts by weight of lanthanum oxide and 10 parts by weight of niobium pentoxide, and then putting the mixture into a ball mill for ball milling to obtain ball milling powder 1; (2) presintering the ball-milled powder 1 at 870 ℃ for 30 min; obtaining a pre-sintering mixture; (3) putting the pre-sintered mixture into a ball mill for ball milling to obtain ball milling powder 2; the obtained ball milling powder 2 is the modified bismuth titanate.

The preparation method comprises the following steps: melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding a single-walled carbon nanotube and modified bismuth titanate, uniformly stirring to obtain an alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

Comparative example 1 preparation of nanocarbon aluminum composite heat conductive material

The raw materials comprise the following components in parts by weight: 80 parts of aluminum; 2 parts of silicon; 1 part of iron; 0.3 part of zinc; 0.2 part of strontium; 0.08 part of copper.

The preparation method comprises the following steps: melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding bismuth titanate, uniformly stirring to obtain an alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

Comparative example 2 preparation of nanocarbon aluminum composite heat conductive material

The raw materials comprise the following components in parts by weight: 80 parts of aluminum; 2 parts of silicon; 1 part of iron; 0.3 part of zinc; 0.2 part of strontium; 0.08 part of copper; 20 parts of modified bismuth titanate;

the modified bismuth titanate is prepared by the following method: (1) mixing 60 parts by weight of bismuth titanate, 20 parts by weight of lanthanum oxide and 20 parts by weight of niobium pentoxide, and then putting the mixture into a ball mill for ball milling to obtain ball milling powder 1; (2) presintering the ball-milled powder 1 at 870 ℃ for 30 min; obtaining a pre-sintering mixture; (3) putting the pre-sintered mixture into a ball mill for ball milling to obtain ball milling powder 2; the obtained ball milling powder 2 is the modified bismuth titanate.

The preparation method comprises the following steps: melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding modified bismuth titanate, uniformly stirring to obtain an alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

Comparative example 2 compared to example 2, no single-walled carbon nanotubes were added to comparative example 2.

Comparative example 3 preparation of nanocarbon aluminum composite heat conductive material

The raw materials comprise the following components in parts by weight: 80 parts of aluminum; 2 parts of silicon; 1 part of iron; 0.3 part of zinc; 0.2 part of strontium; 0.08 part of copper; 0.5 part of single-walled carbon nanotube; 20 parts of modified bismuth titanate;

the modified bismuth titanate is prepared by the following method: (1) mixing 60 parts by weight of bismuth titanate and 40 parts by weight of niobium pentoxide, and then putting the mixture into a ball mill for ball milling to obtain ball milling powder 1; (2) presintering the ball-milled powder 1 at 870 ℃ for 30 min; obtaining a pre-sintering mixture; (3) putting the pre-sintered mixture into a ball mill for ball milling to obtain ball milling powder 2; the obtained ball milling powder 2 is the modified bismuth titanate.

The preparation method comprises the following steps: melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding a single-walled carbon nanotube and modified bismuth titanate, uniformly stirring to obtain an alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

Comparative example 3 differs from example 2 in that comparative example 3 modifies bismuth titanate with only niobium pentoxide, whereas example 2 modifies bismuth titanate with lanthanum oxide and niobium pentoxide.

Comparative example 4 preparation of nanocarbon aluminum composite heat conductive material

The raw materials comprise the following components in parts by weight: 80 parts of aluminum; 2 parts of silicon; 1 part of iron; 0.3 part of zinc; 0.2 part of strontium; 0.08 part of copper; 0.5 part of single-walled carbon nanotube; 20 parts of modified bismuth titanate;

the modified bismuth titanate is prepared by the following method: (1) mixing 60 parts by weight of bismuth titanate and 40 parts by weight of lanthanum oxide, and then putting the mixture into a ball mill for ball milling to obtain ball milling powder 1; (2) presintering the ball-milled powder 1 at 870 ℃ for 30 min; obtaining a pre-sintering mixture; (3) putting the pre-sintered mixture into a ball mill for ball milling to obtain ball milling powder 2; the obtained ball milling powder 2 is the modified bismuth titanate.

The preparation method comprises the following steps: melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding a single-walled carbon nanotube and modified bismuth titanate, uniformly stirring to obtain an alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

Comparative example 4 differs from example 2 in that comparative example 4 modifies bismuth titanate with lanthanum oxide only, whereas example 2 modifies bismuth titanate with lanthanum oxide and niobium pentoxide.

Comparative example 5 preparation of nanocarbon aluminum composite heat conductive material

The raw materials comprise the following components in parts by weight: 80 parts of aluminum; 2 parts of silicon; 1 part of iron; 0.3 part of zinc; 0.2 part of strontium; 0.08 part of copper; 0.5 part of single-walled carbon nanotube; 20 parts of modified bismuth titanate;

the modified bismuth titanate is prepared by the following method: and uniformly mixing 60 parts by weight of bismuth titanate, 20 parts by weight of lanthanum oxide and 20 parts by weight of niobium pentoxide to obtain the modified bismuth titanate.

The preparation method comprises the following steps: melting aluminum, adding silicon, iron, zinc, strontium and copper, uniformly stirring after melting, adding a single-walled carbon nanotube and modified bismuth titanate, uniformly stirring to obtain an alloy liquid, and finally degassing, slagging off and casting the alloy liquid to obtain the nano carbon-aluminum composite heat conduction material.

Comparative example 5 is different from example 2 in that the preparation method of the modified bismuth titanate is different, and comparative example 5 simply mixes lanthanum oxide and niobium pentoxide with bismuth titanate; in the embodiment 2, firstly, the lanthanum oxide, the niobium pentoxide and the bismuth titanate are ball-milled, then, the pre-sintering is carried out, and finally, the ball-milling is carried out.

The thermal conductivity coefficient of the nano carbon-aluminum composite thermal conductive material prepared in the embodiments 1-4 and the comparative examples 1-5 is determined by referring to the method in the national standard GB/T3651-2008, and the thermal expansion coefficient is determined by referring to the method in the GB/T4339-2008; the test results are shown in Table 1.

TABLE 1 determination of the Properties of the nanocarbon-aluminum composite heat-conductive material of the present invention

	Thermal conductivity (W/(m.K))	Coefficient of thermal expansion (. times.10)-6/℃)
			Example 1 nanocarbon aluminum composite thermal conductive Material	177	4.7
Example 2 nanocarbon aluminum composite thermal conductive Material	181	0.76
			Example 3 nanocarbon aluminum composite thermal conductive Material	172	0.89
Example 4 nanocarbon aluminum composite thermal conductive Material	179	0.81
			Comparative example 1 nanocarbon aluminum composite heat conductive material	183	23.5
Comparative example 2 nanocarbon aluminum composite heat conductive material	122	0.79
			Comparative example 3 nanocarbon aluminum composite heat conductive material	168	3.9
Comparative example 4 nanocarbon aluminum composite heat conductive material	176	3.7
			Comparative example 5 nanocarbon aluminum composite heat conductive material	180	4.3

As can be seen from the performance test data of example 1 and comparative example 1; the thermal expansion coefficient of the comparative example 1 is from 23.5 to 4.7, which shows that the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material prepared by taking aluminum, silicon, iron, zinc, strontium and copper as raw materials can be reduced by adding bismuth titanate; meanwhile, the nanocarbon aluminum composite heat conduction material prepared in the embodiment 1 also has an excellent heat conduction coefficient.

The performance test data of the embodiments 2 to 4 show that the thermal expansion coefficient is further greatly reduced compared with that of the embodiment 1, which indicates that the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material can be further greatly reduced by adding the modified bismuth titanate prepared by the method of the invention compared with that of the unmodified bismuth titanate; the thermal expansion coefficient of the obtained nano carbon-aluminum composite heat conduction material is less than 1.

As can be seen from the performance test data of comparative example 2, the thermal conductivity of the nanocarbon aluminum composite thermal conductive material prepared in comparative example 2 is greatly reduced compared with that of example 2 and comparative example 1, which indicates that the thermal conductivity of the nanocarbon aluminum composite thermal conductive material is reduced with the addition of bismuth titanate or modified bismuth titanate; and when the bismuth titanate or the modified bismuth titanate is added, the carbon nano tube is added, so that the technical problem that the heat conductivity of the nano carbon-aluminum composite heat conduction material is reduced along with the addition of the bismuth titanate or the modified bismuth titanate can be effectively solved.

As can be seen from the performance test data of comparative examples 3-4, the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material is not further greatly reduced compared with that of example 1, which indicates that the selection of the modified raw material of bismuth titanate plays a very key role in determining whether the modified bismuth titanate capable of greatly reducing the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material can be obtained; the thermal expansion coefficient of the nano carbon-aluminum composite heat-conducting material can be greatly reduced only by modifying bismuth titanate by adopting lanthanum oxide and niobium pentoxide; the nano carbon-aluminum composite heat conduction material with the thermal expansion coefficient less than 1 can be obtained.

As can be seen from the performance test data of comparative example 5, the thermal expansion coefficient of the bismuth titanate is not further greatly reduced compared with that of example 1, which indicates that the preparation method of the modified bismuth titanate is very critical; the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material can be greatly reduced only by ball-milling lanthanum oxide, niobium pentoxide and bismuth titanate, then pre-sintering and finally ball-milling to prepare the modified bismuth titanate; the thermal expansion coefficient of the nano carbon-aluminum composite heat conduction material cannot be greatly reduced by simply mixing lanthanum oxide, niobium pentoxide and bismuth titanate to prepare the modified bismuth titanate.