CN110804735B - A composite coating for thermal conduction, radiation and heat dissipation for titanium alloys - Google Patents

Abstract

The invention discloses a heat conduction, radiation and heat dissipation composite coating suitable for titanium alloys. The process is as follows: 1. Cold spray the soft metal powder on the surface of the titanium alloy to form a reticulated metal structure layer; 2. The powder of the nano-SiC-spinel-oxide composite material is prepared into a mixed slurry and then sprayed on the reticulated metal On the structural layer, a heat dissipation composite coating is obtained on the surface of the titanium alloy after drying and curing. In the invention, the reticulated metal structure layer with heat conduction function and the non-metal oxide coating with radiation heat dissipation function are compounded, and the mesh metal structure layer is used to increase the area of the heat conduction layer, thereby increasing the contact between the heat conduction layer and the infrared radiation layer It improves the thermal conductivity between the two, and at the same time improves the thermal conductivity and infrared radiation efficiency of the titanium alloy, which solves the problems of the low thermal conductivity of the titanium alloy coating and the poor heat dissipation performance of infrared radiation.

Description

A composite coating for thermal conduction, radiation and heat dissipation for titanium alloys

technical field

The invention belongs to the technical field of metal composite material preparation, in particular to a composite coating for heat conduction, radiation and heat dissipation suitable for titanium alloys.

Background technique

A stable working environment is a necessary condition to ensure the efficient and stable output of the laser. The most important thing is that the operating temperature of the core device should not be too high. With the increase of the measurement distance and the improvement of the measurement response rate of the laser rangefinder, the pulse power of the laser becomes larger and larger. If the heat dissipation efficiency of the laser system is not high, it will directly affect the ranging performance of the laser rangefinder. For the thermal power consumption generated when the laser is working, a hot water storage tank or an air-cooled heat exchange system is generally used for cooling. However, as the distance measuring equipment has higher and higher requirements for miniaturization and light weight, air cooling cannot be used for heat dissipation. The heat dissipation of the laser only relies on the hot melt of the coolant in the water tank to cool down. Once the temperature of the coolant rises to a certain value, it cannot be cooled. Continue to cool the laser.

At present, the power of lasers is getting bigger and bigger, and more and more heat is generated, and the requirements for heat dissipation are getting higher and higher. Due to the strict requirements of the use environment and conditions of laser products, lasers have very high requirements for structural stability, and titanium alloy materials are generally used in large quantities. However, titanium alloy is a metal material with very poor thermal conductivity. After the water tank absorbs a large amount of heat generated by the laser, it cannot be successfully exported through the titanium alloy body, which eventually leads to a series of problems such as increased laser temperature, reduced laser beam quality, and reduced capability. . Therefore, the system must be stopped after working for a certain period of time, and can be used again after the system has cooled down, which seriously affects the usability of the equipment. Therefore, it is necessary to adopt a new type of heat dissipation and cooling technology to improve the heat dissipation capacity of the laser, increase the continuous working time of the system and shorten the cooling recovery time. Therefore, it is necessary to develop a coating material that can be coated on the outside of the casing and can significantly increase the heat dissipation effect.

Heat dissipation coatings mainly include high infrared emissivity coatings and high thermal conductivity coatings. High infrared emissivity coatings can be prepared by paint brushing or magnetron sputtering. High thermal conductivity coatings have high thermal conductivity and can quickly conduct heat away. The research on high thermal conductivity products mainly focuses on non-oxide coatings such as nitrides and carbides, especially nitrides with excellent optical properties. Among them, aluminum nitride has high resistivity, thermal conductivity and good chemical stability, and is widely used in aerospace radiators, semiconductor heat sinks and other products. In recent years, graphene materials have attracted the attention of researchers because of their thermal conductivity as high as 5000 W/m.K, but the thickness of graphene materials is thin, so the heat flux in the lateral heat conduction process is greatly limited. At present, the design research of heat dissipation coating for titanium alloy structural materials mainly focuses on the research of high infrared radiation heat dissipation coating, but due to the limitation of low thermal conductivity and poor thermal conductivity of titanium alloy materials, the heat dissipation effect of infrared radiation is not good; for titanium alloy materials The research on designing composite coatings with high thermal conductivity and high infrared radiation functions has not been reported yet.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a thermal conduction, radiation and heat dissipation composite coating suitable for titanium alloys in view of the deficiencies of the above-mentioned prior art. The heat dissipation composite coating combines a reticulated metal structure layer with heat conduction function and a non-metal oxide coating with radiation heat dissipation function. The contact area of the radiation layer improves the thermal conductivity between the thermal conductivity layer and the infrared radiation layer, thereby improving the thermal conductivity of the titanium alloy while improving the infrared radiation efficiency of the titanium alloy. The problem of poor radiation cooling performance.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is: a composite coating for heat conduction, radiation and heat dissipation suitable for titanium alloys, characterized in that the composite heat dissipation coating is composed of a mesh metal structure layer with heat conduction function and a coating. It is composed of a non-metal oxide coating with radiation heat dissipation function on the mesh metal structure layer, and the heat dissipation composite coating is prepared by the following steps:

Step 1, using the cold spray method to spray the soft metal powder with better thermal conductivity than the titanium alloy on the surface of the titanium alloy to form a mesh metal structure layer;

In step 2, the powder of nano-SiC-spinel-oxide composite material is added to the water glass solvent, and then phenolic resin is added to obtain a mixed slurry, which is sprayed on the mixed slurry obtained in step 1 by a spray curing method. On the reticulated metal structure layer, a non-metal oxide coating is formed by drying and curing, so as to obtain a heat dissipation composite coating on the surface of the titanium alloy; the thermal conductivity of the composite coating is not less than 100W/m.K, and the infrared emission in the 5μm～20μm band The rate is not less than 0.95.

According to the principle of thermodynamics, the heat conduction and radiation of the coating are the keys to heat dissipation, then the heat conduction between the heat conduction layer and the radiation layer is also the key to affect heat dissipation. It is proportional to the area S in the direction of heat conduction, as shown in formula (1):

为温度梯度，“-”表示热量由高温传向低温。In formula (1), λ is the thermal conductivity, S is the heat conduction area, Q is the heat,

For the temperature gradient, "-" means that heat is transferred from high temperature to low temperature.

The contact interface between the thermal conductive layer and the thermal radiation layer has contact thermal resistance, which is the key to affecting the heat transfer of the thermal conductive layer to the radiation layer. If there is no good transfer between the thermal conductive layer and the radiation layer, it will directly affect the heat dissipation of the radiation layer. According to the thermal resistance theory, the most important factor affecting the contact thermal resistance is the contact area. The contact thermal resistance is inversely proportional to the contact area S. The calculation formula of the contact thermal resistance is as follows:

In formula (2), R _c is the contact thermal resistance, k _c is the thermal conductivity, and s is the contact area

The heat-conducting, radiation-dissipating composite coating suitable for titanium alloy of the present invention is composed of a reticulated metal structure layer with heat-conducting function and a non-metal oxide coating having radiation heat-dissipating function. The reticulated metal structure layer (that is, the thermal conductive layer) formed by the metal powder, and then the mixed slurry containing the high infrared radiation composite material is filled and cured on the reticulated metal structure layer by the method of spray curing to form a non-metal oxide coating ( That is, the infrared radiation layer), the area of the thermal conductive layer is effectively increased through the mesh metal structure layer, which in turn increases the contact area between the thermal conductive layer and the infrared radiation layer, reduces the interface contact thermal resistance between the thermal conductive layer and the infrared radiation layer, and improves the The thermal conductivity between the thermal conductivity layer and the infrared radiation layer is improved, so that the thermal conductivity of the titanium alloy is improved while the infrared radiation efficiency of the titanium alloy is improved, and the problems of low thermal conductivity and poor infrared radiation heat dissipation performance of the current titanium alloy coating are solved. .

The above-mentioned composite coating for heat conduction, radiation and heat dissipation for titanium alloys is characterized in that the composition of the soft metal powder in step 1 is copper, copper alloy, aluminum, aluminum alloy, gold, silver or nickel, and soft metal powder is composed of copper, copper alloy, aluminum, aluminum alloy, gold, silver or nickel. The particle size of the metal powder is 20 μm to 40 μm. The heat-dissipating composite coating of the present invention is suitable for the composition and particle size of the soft metal powder commonly used for preparing the heat-conducting layer, which improves the practical value of the present invention.

The above-mentioned composite coating for heat conduction, radiation and heat dissipation suitable for titanium alloys is characterized in that the shape of the mesh holes in the reticulated metal structure layer in step 1 is a parallelogram, and the acute angle of the parallelogram is 45° to 90°, The length of the lower base is 10mm-30mm, the height is 10mm-30mm, and the thickness of the mesh metal structure layer is 5mm-10mm. The reticulated metal structure layer with the above-mentioned preferred structure and parameters prepared by the cold spray method further effectively increases the area of the thermally conductive layer, thereby helping to increase the contact area between the thermally conductive layer and the infrared radiation layer, and to improve the distance between the thermally conductive layer and the infrared radiation layer. thermal conductivity.

The above-mentioned composite coating for heat conduction, radiation and heat dissipation suitable for titanium alloys, characterized in that the oxides in the nano-SiC-spinel-oxide composite material in step 2 are CaCO ₃ , Al ₂ O ₃ , Fe ₂ O ₃ and SiO ₂ , the powder of the nano-SiC-spinel-oxide composite material is prepared by a high-energy ball milling method, and the particle size of the powder of the nano-SiC-spinel-oxide composite material is submicron. The nano-SiC-spinel-oxide composite material with the preferred composition has a high emissivity, and the preparation method and the micro-nano particle size are favorable for the powder of the nano-SiC-spinel-oxide composite material to be formulated into slurry spraying On the reticulated metal structure layer (ie, the thermal conductive layer), a uniformly distributed non-metal oxide coating is formed, so as to exert its radiation heat dissipation performance.

The above-mentioned composite coating for thermal conduction, radiation and heat dissipation for titanium alloys is characterized in that the mass content of the powder of the nano-SiC-spinel-oxide composite material in the mixed slurry described in step 2 is 35% to 65%. %, and the mass content of the phenolic resin is 10% to 20%. The optimized composition of the mixed slurry not only ensures that the nano-SiC-spinel-oxide composite material can fully exert its radiation heat dissipation performance, but also enhances the bonding strength between the slurry and the mesh metal structure layer, and further enhances the thermal conductivity layer. Thermal conductivity with the infrared radiation layer.

Compared with the prior art, the present invention has the following advantages:

1. In the present invention, a reticulated metal structure layer (ie, a heat-conducting layer) with a heat-conducting function and a non-metal oxide coating with a radiative heat-dissipating function are composited to form a heat-dissipating composite coating (ie, an infrared radiation layer) suitable for titanium alloys, First, a mesh metal structure layer formed of high thermal conductivity metal powder is prepared on the surface of titanium alloy by cold spraying method, and then a slurry of radiation material is coated, which effectively increases the area of the thermal conduction layer, thereby increasing the thermal conduction layer and the infrared radiation layer. It reduces the interface thermal resistance between the thermal conduction layer and the infrared radiation layer, and improves the thermal conductivity between the thermal conduction layer and the infrared radiation layer, thereby improving the thermal conductivity of the titanium alloy while improving the infrared radiation efficiency of the titanium alloy. It solves the problems of low thermal conductivity and poor infrared radiation heat dissipation performance of the current titanium alloy coating.

2. The present invention adopts the cold spraying method to prepare the reticulated metal structure layer formed by the high thermal conductivity metal powder on the surface of the titanium alloy, and uses the low temperature solid state deposition characteristics of the cold spraying to effectively avoid the oxidation of the titanium alloy and the high thermal conductivity metal powder, effectively guaranteeing Performance of thermal composite coatings.

3. The present invention adopts the nanometer SiC-spinel-oxide composite material of sub-micron level as the high radiation material, the radiation material of this scale can penetrate each other with the cold sprayed thermal conduction framework, and the sub-micron radiation material is filled in the cold sprayed preparation. In the voids on the surface of the reticulated metal structure layer, the interface thermal resistance between the radiation material and the thermal conductive coating is further significantly reduced, and the heat dissipation efficiency of the titanium alloy is improved.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

FIG. 1 is a schematic structural diagram of a thermally conductive, radiated, heat-dissipating composite coating suitable for titanium alloys according to the present invention.

FIG. 2 is a schematic cross-sectional structure diagram of a thermally conductive, radiated, heat-dissipating composite coating suitable for titanium alloys according to the present invention.

Explanation of reference numbers:

1—Titanium alloy substrate; 2—Mesh metal structure layer; 3—Non-metal oxide coating.

Detailed ways

As shown in FIG. 1 and FIG. 2 , the thermally conductive, radiant and heat-dissipating composite coatings suitable for titanium alloys in Examples 1 to 4 of the present invention are all composed of a reticulated metal structure with thermal conductivity coated on the titanium alloy substrate 1 . The layer 2 and the non-metallic oxide coating 3 coated on the mesh metal structure layer 2 with the function of radiation heat dissipation are composed.

Example 1

The composite coating of this embodiment is prepared by the following steps:

Step 1. Use cold spraying method to spray copper powder with a particle size of 20 μm to 40 μm on the surface of the titanium alloy to form a mesh metal structure layer; the pressure of the cold spraying is 1MPa, the spraying distance is 20mm, the spraying gas is nitrogen, and the spraying gas The preheating temperature is 350°C; the shape of the mesh in the mesh metal structure layer is a parallelogram, the acute angle of the parallelogram is 45°, the length of the lower base is 10mm, and the height is 10mm. The thickness is 5mm;

In step 2, the powder of nano-SiC-spinel-oxide composite material is added to the water glass solvent, and then phenolic resin is added to obtain a mixed slurry, which is sprayed on the mixed slurry obtained in step 1 by a spray curing method. On the reticulated metal structure layer, a non-metal oxide coating is formed by drying and curing at 120°C, and a composite coating is obtained on the surface of the titanium alloy; the nano-SiC-spinel-oxide composite material contains nano-SiC, CaCO ₃ , The volume ratio of Al ₂ O ₃ , Fe ₂ O ₃ and SiO ₂ is 1:2:1:1:1, the powder of the nano-SiC-spinel-oxide composite material is prepared by high-energy ball milling, and the nano The particle size of the powder of the SiC-spinel-oxide composite material is 100 nm to 1000 nm; the mass content of the powder of the nano-SiC-spinel-oxide composite material in the mixed slurry is 30%, and the mass content of the phenolic resin is 30%. is 10%; the thermal conductivity of the composite coating is 250W/mK, and the infrared emissivity in the 5μm-20μm band is not less than 0.95.

The composition of the soft metal powder in this embodiment may also be copper alloy, aluminum, aluminum alloy, gold, silver or nickel.

Example 2

The composite coating of this embodiment is prepared by the following steps:

Step 1. Use cold spraying method to spray aluminum powder with a particle size of 20 μm to 40 μm on the surface of the titanium alloy to form a mesh metal structure layer; the pressure of the cold spraying is 2MPa, the spraying distance is 40mm, the spraying gas is nitrogen, and the spraying gas The preheating temperature is 220°C; the mesh shape in the mesh metal structure layer is a parallelogram, the acute angle of the parallelogram is 90°, the length of the lower base is 30mm, and the height is 30mm. The thickness is 10mm;

In step 2, the powder of nano-SiC-spinel-oxide composite material is added to the water glass solvent, and then phenolic resin is added to obtain a mixed slurry, which is sprayed on the mixed slurry obtained in step 1 by a spray curing method. On the reticulated metal structure layer, a non-metal oxide coating is formed by drying and curing at 120°C, and a composite coating is obtained on the surface of the titanium alloy; the nano-SiC-spinel-oxide composite material contains nano-SiC, CaCO ₃ , The volume ratio of Al ₂ O ₃ , Fe ₂ O ₃ and SiO ₂ is 1:2:1:1:1, the powder of the nano-SiC-spinel-oxide composite material is prepared by high-energy ball milling, and the nano The particle size of the powder of the SiC-spinel-oxide composite material is 100 nm to 1000 nm; the mass content of the powder of the nano-SiC-spinel-oxide composite material in the mixed slurry is 65%, and the mass content of the phenolic resin is 65%. is 20%; the thermal conductivity of the composite coating is 100W/mK, and the infrared emissivity in the 5μm-20μm band is not less than 0.95.

The composition of the soft metal powder in this embodiment may also be copper alloy, aluminum, aluminum alloy, gold, silver or nickel.

Example 3

The composite coating of this embodiment is prepared by the following steps:

Step 1. Use cold spraying method to spray gold powder with a particle size of 20 μm to 40 μm on the surface of the titanium alloy to form a mesh metal structure layer; the pressure of the cold spraying is 1MPa, the spraying distance is 20mm, the spraying gas is nitrogen, and the spraying gas The preheating temperature is 350°C; the shape of the mesh in the mesh metal structure layer is a parallelogram, the acute angle of the parallelogram is 45°, the length of the lower base is 10mm, and the height is 10mm. The thickness is 5mm;

In step 2, the powder of nano-SiC-spinel-oxide composite material is added to the water glass solvent, and then phenolic resin is added to obtain a mixed slurry, which is sprayed on the mixed slurry obtained in step 1 by a spray curing method. On the reticulated metal structure layer, a non-metal oxide coating is formed by drying and curing at 120°C, and a composite coating is obtained on the surface of the titanium alloy; the nano-SiC-spinel-oxide composite material contains nano-SiC, CaCO ₃ , The volume ratio of Al ₂ O ₃ , Fe ₂ O ₃ and SiO ₂ is 1:2:1:1:1, the powder of the nano-SiC-spinel-oxide composite material is prepared by high-energy ball milling, and the nano The particle size of the powder of the SiC-spinel-oxide composite material is 100 nm to 1000 nm; the mass content of the powder of the nano-SiC-spinel-oxide composite material in the mixed slurry is 35%, and the mass content of the phenolic resin is 35%. is 10%; the thermal conductivity of the composite coating is 250W/mK, and the infrared emissivity in the 5μm-20μm band is not less than 0.95.

The composition of the soft metal powder in this embodiment may also be copper, copper alloy, aluminum, aluminum alloy, silver or nickel.

Example 4

The composite coating of this embodiment is prepared by the following steps:

Step 1. Use cold spraying method to spray silver powder with a particle size of 20 μm to 40 μm on the surface of the titanium alloy to form a mesh metal structure layer; the pressure of the cold spraying is 1.5MPa, the spraying distance is 30mm, the spraying gas is nitrogen, and the spraying The preheating temperature of the gas is 300°C; the mesh shape in the mesh metal structure layer is a parallelogram, the acute angle of the parallelogram is 65°, the length of the lower base is 20mm, and the height is 20mm. The thickness of the layer is 8mm;

In step 2, the powder of nano-SiC-spinel-oxide composite material is added to the water glass solvent, and then phenolic resin is added to obtain a mixed slurry, which is sprayed on the mixed slurry obtained in step 1 by a spray curing method. On the reticulated metal structure layer, a non-metal oxide coating is formed by drying and curing at 120°C, and a composite coating is obtained on the surface of the titanium alloy; the nano-SiC-spinel-oxide composite material contains nano-SiC, CaCO ₃ , The volume ratio of Al ₂ O ₃ , Fe ₂ O ₃ and SiO ₂ is 1:2:1:1:1, the powder of the nano-SiC-spinel-oxide composite material is prepared by high-energy ball milling, and the nano The particle size of the powder of the SiC-spinel-oxide composite material is 100 nm to 1000 nm; the mass content of the powder of the nano-SiC-spinel-oxide composite material in the mixed slurry is 50%, and the mass content of the phenolic resin is 50%. is 15%; the thermal conductivity of the composite coating is 400W/mK, and the infrared emissivity in the 5μm-20μm band is not less than 0.95.

The composition of the soft metal powder in this embodiment may also be copper, copper alloy, aluminum, aluminum alloy, gold or nickel.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any way. Any simple modifications, changes and equivalent changes made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solutions of the present invention.

Claims (5)

1. a heat-conducting radiation heat-dissipating composite coating suitable for titanium alloys, is characterized in that, this heat-dissipating composite coating consists of a reticulated metal structure layer with thermal conductivity and a reticulated metal structure layer coated with a radiative heat-dissipating function. The non-metal oxide coating is composed, and the heat dissipation composite coating is prepared by the following steps: Step 1, using the cold spray method to spray the soft metal powder with better thermal conductivity than the titanium alloy on the surface of the titanium alloy to form a mesh metal structure layer; In step 2, the powder of nano-SiC-spinel-oxide composite material is added to the water glass solvent, and then phenolic resin is added to obtain a mixed slurry, which is sprayed on the mixed slurry obtained in step 1 by a spray curing method. On the reticulated metal structure layer, a non-metal oxide coating is formed by drying and curing, so as to obtain a heat dissipation composite coating on the surface of the titanium alloy; the thermal conductivity of the composite coating is not less than 100W/m.K, and the infrared emission in the 5μm～20μm band The rate is not less than 0.95. 2. A composite coating for thermal conduction, radiation and heat dissipation suitable for titanium alloys according to claim 1, wherein the soft metal powder in step 1 is composed of copper, copper alloy, aluminum, aluminum alloy, gold , silver or nickel, the particle size of the soft metal powder is 20μm～40μm. 3. A composite coating for heat conduction, radiation and heat dissipation suitable for titanium alloys according to claim 1, wherein the mesh shape in the reticulated metal structure layer in the step 1 is a parallelogram, and the acute angle of the parallelogram is a parallelogram. It is 45°～90°, the length of the lower base is 10mm～30mm, the height is 10mm～30mm, and the thickness of the mesh metal structure layer is 5mm～10mm. 4. a kind of composite coating suitable for heat conduction, radiation and heat dissipation of titanium alloy according to claim 1, is characterized in that, the oxide in the nano-SiC-spinel-oxide composite material described in step 2 is Al ₂ O ₃ , Fe ₂ O ₃ and SiO ₂ , the powder of the nano-SiC-spinel-oxide composite material is prepared by a high-energy ball milling method, and the particle size of the powder of the nano-SiC-spinel-oxide composite material is submicron level. 5. a kind of composite coating suitable for heat conduction, radiation and heat dissipation of titanium alloy according to claim 1, is characterized in that, in the mixed slurry described in step 2, the powder of nano-SiC-spinel-oxide composite material is The mass content is 35% to 65%, and the mass content of the phenolic resin is 10% to 20%.

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