ZrW2O8-coated ZrO2-Cu double-shell structure powder as well as preparation method and application thereof

Abstract

The invention discloses ZrW2O8-coated ZrO2-Cu double-shell structure powder as well as a preparation method and application thereof, and belongs to the technical field of shell structure powder. An inner shell layer and an outer shell layer are sequentially coated outside an inner core of the double-shell structure powder; wherein the inner core is anisotropic negative thermal expansion material zirconium tungstate (ZrW2O8), the inner shell layer is zirconium oxide (ZrO2) with high temperature resistance, low thermal expansion and high hardness, and the outer shell layer is metal copper with good wettability to ceramics and metals. Zirconium oxide with high-temperature resistance and low thermal expansion coefficient is selected as an inner shell layer material for protecting zirconium tungstate from high-temperature volatilization and phase change; in order to improve the compactness of zirconium oxide and the wettability of ceramic / metal, metal / ceramic high-wettability Cu is selected as a shell layer material, so that ZrW2O8-ZrO2-Cu double-shell-layer structure powder which can be applied to metal cladding and welding is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of shell structure powders, and in particular to a ZrW 2 O 8 @ZrO 2 -Cu double-shell structure powder and its preparation method and application. Background Art

[0002] There are many methods for preparing brake disc materials, such as powder metallurgy, stirring casting and laser cladding. Laser cladding technology has the characteristics of rapid cooling and heating, which can obtain finer grains and greatly improve the performance of brake disc materials. However, laser cladding faces a huge challenge. If the temperature of laser cladding is too high, thermal stress will be generated during the cladding process, which may cause cracks in the material. Studies have found that adding zirconium tungstate (ZrW) with negative thermal expansion to the cladding material can effectively improve the performance of brake disc materials. 2 O 8 ) can effectively reduce thermal stress and thus inhibit the initiation of cracks.

[0003] But ZrW 2 O 8 At about 800℃, it will decompose into ZrO 2 and WO 4 If you want ZrW 2 O 8 In order to still have this negative thermal expansion effect under laser cladding, it is necessary to suppress ZrW 2 O 8 The present invention proposes to decompose ZrW 2 O 8 The surface is covered with a layer of heat-resistant and high-temperature resistant material in order to absorb or isolate the large amount of heat generated by laser cladding. Summary of the invention

[0004] The object of the present invention is to provide a ZrW 2 O 8 @ZrO 2 -Cu double-shell structure powder and preparation method thereof, the double-shell structure powder can alleviate the thermal decomposition of zirconium tungstate and can be well combined with the metal used for laser cladding.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A ZrW 2 O 8 @ZrO 2 -Cu double-shell structure powder, which is a core-shell structure, and has a double-shell structure, that is, the inner shell and the outer shell are sequentially covered outside the inner core; wherein: the inner core is anisotropic negative thermal expansion material zirconium tungstate (ZrW2 O 8 ), the inner shell is zirconium oxide (ZrO 2 ), the outer shell layer is metallic copper which has good wettability to ceramics and metals.

[0007] Furthermore, the zirconium tungstate (ZrW 2 O 8 ) is 6-26μm in size, zirconium tungstate coated zirconium oxide (ZrW 2 O 8 @ZrO 2 ) after ZrO 2 The inner shell thickness is 2-6 μm, ZrW 2 O 8 @ZrO 2 -The thickness of the Cu outer shell layer of the Cu double-shell structure powder is 2-4 μm.

[0008] Furthermore, the ZrW 2 O 8 @ZrO 2 -The preparation method of Cu double shell structure powder comprises the following steps:

[0009] (1) Preparation of zirconium tungstate suspension:

[0010] Use a measuring cylinder to measure an appropriate amount of zirconium n-butoxide, add it into a beaker containing zirconium tungstate powder and stir for 10-15 minutes, then put the beaker into an ultrasonic cleaner for ultrasonic dispersion, and then stir to obtain a stable zirconium tungstate suspension;

[0011] (2) Preparation of zirconium oxide-coated zirconium tungstate powder:

[0012] Under magnetic stirring conditions, deionized water is slowly added dropwise to a beaker containing a zirconium tungstate suspension to hydrolyze the zirconium n-butoxide, and the generated zirconium hydroxide is wrapped on the surface of the zirconium tungstate. After the reaction is completed, the obtained mixture is vacuum filtered, and the unhydrolyzed zirconium n-butoxide is firstly filtered with alcohol, and then the remaining alcohol is filtered with deionized water; the solid product obtained after the filtration is dried to obtain a composite powder precursor; the composite powder precursor is calcined in a muffle furnace to decompose the zirconium hydroxide into zirconium oxide to obtain ZrW 2 O 8 @ZrO 2 Block structure, grinding in a mortar to obtain zirconium oxide coated zirconium tungstate powder (ZrW 2 O 8 @ZrO 2 Powder);

[0013] (3) Preparation of ZrW 2 O 8@ZrO 2 -Cu double shell structure powder:

[0014] The zirconium oxide-coated zirconium tungstate powder (ZrW 2 O 8 @ZrO 2 The powder is subjected to an acidification treatment in a hydrochloric acid solution, and then subjected to a sensitization and activation treatment. The activated powder is coated with copper in a copper plating solution, and then washed with deionized water and alcohol, and then placed in a vacuum drying oven for drying to obtain the ZrW 2 O 8 @ZrO 2 -Cu double shell structure powder.

[0015] Furthermore, in step (1), the zirconium tungstate powder has a particle size of 6-26 μm and an appearance of a smooth irregular polyhedral structure.

[0016] Furthermore, in step (1), the ratio of zirconium n-butoxide to zirconium tungstate powder is (20-40) ml: (2-4) g; the ultrasonic dispersion time in the ultrasonic cleaning machine is 10-30 min, and the stirring time after ultrasonic dispersion is 5-10 min.

[0017] Furthermore, in step (2), the magnetic stirring is carried out in a constant temperature heating magnetic stirrer, the stirring time is 1.5-2.5 hours, the stirring temperature is set to 30-50° C., and the volume of deionized water added is 3% to 15% of the volume of zirconium n-butoxide.

[0018] Furthermore, in step (2), the vacuum filtration is carried out in a vacuum filter, first filtering 3-5 times under alcohol washing conditions, and then filtering 3-5 times under deionized water washing conditions.

[0019] Furthermore, in step (2), the drying process is carried out in a vacuum drying oven, the drying time is 8-10 hours, and the drying temperature is 50-60°C.

[0020] Furthermore, in step (2), the calcination temperature is 450-550° C., the calcination time is 3.5-4.5 h, and the powder is naturally cooled to room temperature after calcination and ground with a mortar.

[0021] Furthermore, in step (3), the acidification treatment refers to soaking the zirconium oxide-coated zirconium tungstate powder in 10wt.% hydrochloric acid for 0.5-1h; the sensitizing solution used for the sensitization treatment is a stannous chloride solution, and the sensitization time is 10-20min; the activation solution used for the activation treatment is a palladium chloride solution, and the activation time is 10-20min; the activated powder is placed in a copper plating solution for copper plating, and an oxidation-reduction reaction occurs to form a dense copper shell structure. After the copper plating is completed, it is first stirred and washed with deionized water for 3-5 times, and then stirred and washed with anhydrous ethanol for 2-3 times; finally, it is dried in a vacuum drying oven at 50-60°C for 2-4h.

[0022] Furthermore, in the stannous chloride solution (sensitizing solution), stannous chloride (SnCl 2 ·H 2 O) 20g / L, hydrochloric acid (HCl) 40ml / L, the rest is water;

[0023] Furthermore, in the palladium chloride solution (activation solution), palladium chloride (PdCl 2 )0.25g / L, hydrochloric acid (HCl) 2.5ml / L, the rest is water;

[0024] Furthermore, the copper plating solution is composed of: copper sulfate pentahydrate (CuSO 4 ·5H 2 O) 16-20g / L, potassium sodium tartrate (KnaC 4 H 4 O 6 ·4H 2 O) 20-25g / L, EDTA-2Na 25-30g / L, sodium hydroxide (NaOH) 12-20g / L, formaldehyde 12-20ml / L, and the rest is water.

[0025] Furthermore, the ZrW 2 O 8 @ZrO 2 -Cu double-shell structure powder is used in laser cladding and is added to the cladding material used; the double-shell structure powder can better protect the negative thermal expansion of its zirconium tungstate, reduce the loss of zirconium tungstate during cladding and welding, reduce the thermal expansion performance of metal cladding and welding, and thus reduce the cracks caused by stress generated in some materials under rapid cooling and heating environments.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. ZrW prepared by the present invention 2 O 8 @ZrO 2-Cu double-shell structure powder can reduce the cracks of cladding materials caused by rapid temperature changes to a certain extent, and improve the performance of the poor interface bonding between the ceramic phase and the metal phase to a certain extent.

[0028] 2. The present invention adopts ZrW 2 O 8 The powder is coated with a layer of ZrO 2 Particles, forming ZrW 2 O 8 @ZrO 2 Core-shell structure. The main purpose is to make ZrO 2 Shell protection core structure ZrW 2 O 8 , protecting its negative thermal expansion properties, ZrO 2 The shell can insulate and absorb heat. 2 The ceramic structure has poor interface bonding with metal. In order to make ZrW 2 O 8 @ZrO 2 The core-shell structure can better combine with metal materials. 2 O 8 @ZrO 2 The surface of the core-shell structure is coated with a layer of copper shell, which can wet the metal and solve the problem of poor interface bonding and dispersion uniformity between the metal phase and the ceramic phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Preparation of ZrW for the present invention 2 O 8 @ZrO 2 -Flowchart of Cu double shell structure powder.

[0030] Figure 2 Preparation of ZrW for the present invention 2 O 8 @ZrO 2 -Schematic diagram of the three-dimensional structure of Cu double-shell structure powder;

[0031] Figure 3 For ZrW 2 O 8 High-resolution SEM photos of

[0032] Figure 4 The ZrW prepared in Example 3 2 O 8 @ZrO 2 High-resolution SEM photos of structural powders;

[0033] Figure 5The ZrW prepared in Example 3 2 O 8 @ZrO 2 -High-resolution SEM images of Cu double-shell structure powders;

[0034] Figure 6 For Al 0.3 ZrW added to CoCrNi 2 O 8 Powder and adding ZrW 2 O 8 @ZrO 2 -Cu double-shell structure powder laser cladding layer SEM image; where: (a) adding ZrW 2 O 8 Powder; (b) adding ZrW 2 O 8 @ZrO 2 -Cu double shell structure powder. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with the examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are the conventional conditions of the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0036] At present, zirconium tungstate materials with anisotropic negative thermal expansion are selected to reduce the thermal expansion behavior of the cladding material. However, zirconium tungstate will decompose at about 800°C. Therefore, in order to improve the thermal deformation and cracking problems during laser cladding and welding, the present invention selects zirconium oxide with high temperature resistance / low thermal expansion coefficient as the inner shell material to protect the high-temperature volatilization and phase change of zirconium tungstate; in order to improve the density of zirconium oxide and the wettability of ceramics / metals, Cu with high wettability of metals / ceramics is selected as the outer shell material, thereby preparing ZrW which can be used for metal cladding and welding. 2 O 8 @ZrO 2 -Cu double shell structure powder.

[0037] The following examples prepare ZrW 2 O 8 @ZrO 2 -Cu double shell structure powder process Figure 1 As shown, the raw material zirconium tungstate powder (ZrW 2 O 8 ) high-resolution SEM photos such as Figure 3 The three-dimensional structure of the prepared double-shell structure powder is shown in Figure 2 shown.

[0038] Embodiment 1:

[0039] Weigh 2.5g of zirconium tungstate powder with a balance and put it into a clean beaker. Use a measuring cylinder to measure 20ml of zirconium n-butoxide and pour it into the beaker. Stir with a glass rod for 10 minutes. Cover the beaker with a layer of plastic wrap, press firmly on all sides, put it into an ultrasonic cleaner for ultrasonic dispersion for 20 minutes, and stir again for 10 minutes to obtain a stable zirconium tungstate suspension.

[0040] A stirring bar was added to the beaker, and the mixture was placed in a constant temperature heated magnetic stirrer at 40°C and stirred for 2 hours. During the magnetic stirring process, 2 ml of deionized water was slowly dripped into the beaker to hydrolyze the zirconium n-butoxide, and the generated zirconium hydroxide was coated on the surface of the zirconium tungstate.

[0041] After magnetic stirring, the mixed material obtained after the hydrolysis reaction is vacuum filtered with a vacuum pump, and the unhydrolyzed zirconium n-butoxide is first washed with alcohol, and then the remaining alcohol is washed with deionized water; the solid product obtained after filtration is placed in a vacuum drying oven and dried at 50°C for 9 hours to obtain a composite powder precursor.

[0042] After drying, the composite powder precursor was calcined in a muffle furnace at 500 °C for 4 h. The agglomerated powder was ground into zirconium tungstate powder (ZrW 2 O 8 @ZrO 2 powder).

[0043] The prepared zirconium oxide-coated zirconium tungstate powder (ZrW 2 O 8 @ZrO 2 The powder was first treated with 10% hydrochloric acid for acidification, then sensitized with stannous chloride solution for 10 minutes, and then activated with palladium chloride solution for 10 minutes; finally, the powder surface was coated with copper by copper plating, and after the copper plating, the powder was washed with water for 3 times, then washed with anhydrous ethanol for 3 times, and dried in a vacuum oven at 50°C for 3 hours to obtain the ZrW 2 O 8 @ZrO 2 -Cu double shell structure powder.

[0044] Among them: the stannous chloride solution used for sensitization treatment is 100ml, the composition is: stannous chloride (SnCl 2 ·H 2 O) 20g / L, hydrochloric acid (HCl) 40ml / L, the balance is water.

[0045] The palladium chloride solution used for activation treatment is 100 ml in total, and its composition is: palladium chloride (PdCl 2)0.25g / L, hydrochloric acid (HCl) 2.5ml / L, and the balance is water.

[0046] The copper plating solution used is 250 ml, and its composition is: copper sulfate pentahydrate (CuSO 4 ·5H 2 O) 4g, potassium sodium tartrate (KnaC 4 H 4 O 6 ·4H 2 O) 5g, EDTA-2Na 6.25g, sodium hydroxide (NaOH) 3.5g, formaldehyde 3.5ml, and the rest is water.

[0047] In this embodiment, zirconium tungstate coated zirconium oxide (ZrW 2 O 8 @ZrO 2 ) after ZrO 2 The inner shell thickness is 2-3 μm, ZrW 2 O 8 @ZrO 2 -The thickness of the Cu outer shell layer of the Cu double-shell structure powder is 2-4 μm.

[0048] Embodiment 2:

[0049] Weigh 2.5g of zirconium tungstate powder with a balance and put it into a clean beaker. Use a measuring cylinder to measure 20ml of zirconium n-butoxide and pour it into the beaker. Stir with a glass rod for 10 minutes. Cover the beaker with a layer of plastic wrap, press firmly on all sides, put it into an ultrasonic cleaner for ultrasonic dispersion for 20 minutes, and stir again for 10 minutes to obtain a stable zirconium tungstate suspension.

[0050] A stirring bar was added to the beaker, and the mixture was placed in a constant temperature heated magnetic stirrer at 50°C and stirred for 2 hours. During the magnetic stirring process, 2 ml of deionized water was slowly dripped in to hydrolyze the zirconium n-butoxide, and the generated zirconium hydroxide was wrapped on the surface of the zirconium tungstate.

[0051] After magnetic stirring, the mixed material obtained after the hydrolysis reaction is filtered with a vacuum pump, and the unhydrolyzed zirconium n-butoxide is first washed with alcohol, and then the remaining alcohol is washed with deionized water; the solid product obtained after filtration is placed in a vacuum drying oven and dried at 50°C for 9 hours to obtain a composite powder precursor.

[0052] The composite powder precursor obtained after drying was calcined in a muffle furnace at 500°C for 4 h, and the agglomerated powder obtained was ground into zirconium tungstate powder (ZrW 2 O 8 @ZrO 2 powder).

[0053] The prepared zirconium oxide-coated zirconium tungstate powder (ZrW2 O 8 @ZrO 2 The process is as follows: firstly, the powder is treated with an acidification treatment with a hydrochloric acid solution having a mass fraction of 10%, then the powder is sensitized with a stannous chloride solution for 10 minutes, and then the powder is activated with a palladium chloride solution for 10 minutes; finally, the powder surface is coated with copper by copper plating, and after the copper plating treatment, the powder is first washed with water for 3 times, then washed with anhydrous ethanol for 3 times, and then placed in a vacuum oven at 50°C for 3 hours to obtain the ZrW 2 O 8 @ZrO 2 -Cu double shell structure powder.

[0054] Among them: the stannous chloride solution used for sensitization treatment is 100ml, the composition is: stannous chloride (SnCl 2 ·H 2 O) 20g / L, hydrochloric acid (HCl) 40ml / L, the balance is water.

[0055] The palladium chloride solution used for activation treatment is 100 ml in total, and its composition is: palladium chloride (PdCl 2 )0.25g / L, hydrochloric acid (HCl) 2.5ml / L, and the balance is water.

[0056] The copper plating solution used is 250 ml, including: copper sulfate pentahydrate (CuSO 4 ·5H 2 O) 4g, potassium sodium tartrate (KnaC 4 H 4 O 6 ·4H 2 O) 5g, EDTA-2Na 6.25g, sodium hydroxide (NaOH) 3.5g, formaldehyde 3.5ml, and the rest is water.

[0057] In this embodiment, zirconium tungstate coated zirconium oxide (ZrW 2 O 8 @ZrO 2 ) after ZrO 2 The inner shell thickness is 2-3 μm, ZrW 2 O 8 @ZrO 2 -The thickness of the Cu outer shell layer of the Cu double-shell structure powder is 2-4 μm.

[0058] Embodiment 3:

[0059] Weigh 2.5g of zirconium tungstate powder with a balance and put it into a clean beaker. Use a measuring cylinder to measure 30ml of zirconium n-butoxide and pour it into the beaker. Stir with a glass rod for 10 minutes. Cover the beaker with a layer of plastic wrap, press firmly on all sides, put it into an ultrasonic cleaner for ultrasonic dispersion for 20 minutes, and stir again for 10 minutes to obtain a stable zirconium tungstate suspension.

[0060] A stirring bar was added to the beaker, and the mixture was placed in a constant temperature heated magnetic stirrer at 40°C and stirred for 2 hours. During the magnetic stirring process, 2 ml of deionized water was slowly dripped into the beaker to hydrolyze the zirconium n-butoxide, and the generated zirconium hydroxide was coated on the surface of the zirconium tungstate.

[0061] After magnetic stirring, the mixed material obtained after the hydrolysis reaction is filtered with a vacuum pump, and the unhydrolyzed zirconium n-butoxide is first washed with alcohol, and then the remaining alcohol is washed with deionized water; the solid product obtained after filtration is placed in a vacuum drying oven at 50°C for 8 hours to obtain a composite powder precursor.

[0062] The composite powder precursor obtained after drying was calcined in a muffle furnace at 500°C for 4 h, and the agglomerated powder obtained was ground to obtain zirconium tungstate powder coated with zirconium oxide (ZrW 2 O 8 @ZrO 2 powder).

[0063] The prepared zirconium oxide-coated zirconium tungstate powder (ZrW 2 O 8 @ZrO 2 The powder was firstly treated with a hydrochloric acid solution having a mass fraction of 10%, and then the powder was sensitized with a stannous chloride solution for 10 minutes, and then the powder was activated with a palladium chloride solution for 10 minutes; finally, the powder surface was coated with copper by copper plating, and after the copper plating, the powder was first washed with water for 3 times, and then washed with anhydrous ethanol for 3 times, and then placed in a vacuum oven at 50°C for 3 hours to obtain the ZrW 2 O 8 @ZrO 2 -Cu double shell structure powder.

[0064] Among them: the stannous chloride solution used for sensitization treatment is 100ml, the composition is: stannous chloride (SnCl 2 ·H 2 O) 20g / L, hydrochloric acid (HCl) 40ml / L, the balance is water.

[0065] The palladium chloride solution used for activation treatment is 100 ml in total, and its composition is: palladium chloride (PdCl 2 )0.25g / L, hydrochloric acid (HCl) 2.5ml / L, and the balance is water.

[0066] The copper plating solution used is 250 ml, and its composition is: copper sulfate pentahydrate (CuSO 4 ·5H 2 O) 4g, potassium sodium tartrate (KnaC 4 H 4 O 6 ·4H 2 O) 5g, EDTA-2Na 6.25g, sodium hydroxide (NaOH) 3.5g, formaldehyde 3.5ml, and the rest is water.

[0067] In this embodiment, zirconium tungstate coated zirconium oxide (ZrW 2 O 8 @ZrO 2 ) after ZrO 2 The inner shell thickness is 2-6 μm, ZrW 2 O 8 @ZrO 2 -The thickness of the Cu outer shell layer of the Cu double-shell structure powder is 2-4 μm.

[0068] The ZrW prepared in this example 2 O 8 @ZrO 2 SEM photos of structural powders are shown in Figure 4 As shown, it can be seen that ZrO 2 The coating is relatively complete, and the prepared ZrW 2 O 8 @ZrO 2 -SEM photos of Cu double shell structure powders Figure 5 As shown, it can be seen that the copper particles are uniformly wrapped in ZrW 2 O 8 @ZrO 2 On the surface.

[0069] Embodiment 4:

[0070] Laser cladding test:

[0071] In the cladding material (Al 0.3 CoCrNi) with ZrW 2 O 8 Powder (accounting for 15wt% of the cladding material) is then laser clad. Figure 6 (a) is the microstructure of the cladding layer, which shows obvious cracks. The reason is that zirconium tungstate decomposes when heated at 800°C, and its negative thermal expansion property fails, which does not play a role in inhibiting crack formation.

[0072] In the cladding material (Al 0.3 ZrW prepared in Example 3 was added to CoCrNi 2 O 8 @ZrO2 -Cu double shell structure powder (accounting for 15wt% of the cladding material) is then laser clad. Figure 6 (b) is the microstructure diagram of the obtained cladding layer. It can be seen that there are no obvious cracks and the density can reach more than 99%, indicating that the coating effect of this powder does protect its core structure zirconium tungstate, retains its negative thermal expansion properties, and reduces the cracks caused by the stress generated in the material during the rapid cooling and heating process.

Claims

1. A ZrW2O8@ZrO2-Cu double-shell structure powder, characterized in that: The powder is a core-shell structure and has a double-shell structure, that is, the inner shell and the outer shell are sequentially covered outside the inner core; wherein: the inner core is zirconium tungstate (ZrW2O8), an anisotropic negative thermal expansion material; the inner shell is zirconium oxide (ZrO2) with high temperature resistance, low thermal expansion and high hardness; and the outer shell is metal copper with good wettability to ceramics and metals.

2. The ZrW2O8@ZrO2-Cu double-shell structure powder according to claim 1, characterized in that: The size of the zirconium tungstate (ZrW2O8) is 6-26 μm, the thickness of the ZrO2 inner shell after zirconium tungstate coated with zirconium oxide (ZrW2O8@ZrO2) is 2-6 μm, and the thickness of the Cu outer shell of the ZrW2O8@ZrO2-Cu double-shell structure powder is 2-4 μm.

3. The method for preparing the ZrW2O8@ZrO2-Cu double-shell structure powder according to claim 1 or 2, characterized in that: The method comprises the following steps: (1) Preparation of zirconium tungstate suspension: Use a measuring cylinder to measure an appropriate amount of zirconium n-butoxide, add it into a beaker containing zirconium tungstate powder and stir for 10-15 minutes, then put the beaker into an ultrasonic cleaner for ultrasonic dispersion, and then stir to obtain a stable zirconium tungstate suspension; (2) Preparation of zirconium oxide-coated zirconium tungstate powder: Under magnetic stirring conditions, deionized water is slowly added dropwise to a beaker containing a zirconium tungstate suspension to hydrolyze the zirconium n-butoxide, and the generated zirconium hydroxide is wrapped on the surface of the zirconium tungstate. After the reaction is completed, the obtained mixture is vacuum filtered, and the unhydrolyzed zirconium n-butoxide is first filtered with alcohol, and then the remaining alcohol is filtered with deionized water; the solid product obtained after the filtration is dried to obtain a composite powder precursor; the composite powder precursor is calcined in a muffle furnace to decompose the zirconium hydroxide into zirconium oxide to obtain a ZrW2O8@ZrO2 block structure, and the zirconium oxide-coated zirconium tungstate powder (ZrW2O8@ZrO2 powder) is obtained by grinding in a mortar; (3) Preparation of ZrW2O8@ZrO2-Cu double-shell structure powder: The zirconium oxide-coated zirconium tungstate powder (ZrW2O8@ZrO2 powder) prepared in step (2) is subjected to an acidification treatment in a hydrochloric acid solution, and then subjected to a sensitization and activation treatment. The activated powder is coated with copper in a copper plating solution, and then washed with deionized water and alcohol, and then placed in a vacuum drying oven for drying to obtain the ZrW2O8@ZrO2-Cu double-shell structure powder.

4. The method for preparing the ZrW2O8@ZrO2-Cu double-shell structure powder according to claim 3, characterized in that: In step (1), the zirconium tungstate powder has a particle size of 6-26 μm and a smooth irregular polyhedral structure.

5. The method for preparing the ZrW2O8@ZrO2-Cu double-shell structure powder according to claim 3, characterized in that: In step (1), the ratio of zirconium n-butoxide to zirconium tungstate powder is (20-40) ml: (2-4) g; the ultrasonic dispersion time in the ultrasonic cleaning machine is 10-30 min, and the stirring time after ultrasonic dispersion is 5-10 min.

6. The method for preparing the ZrW2O8@ZrO2-Cu double-shell structure powder according to claim 3, characterized in that: In step (2), the magnetic stirring is carried out in a constant temperature heating magnetic stirrer, the stirring time is 1.5-2.5 hours, the stirring temperature is set to 30-50° C., and the volume of deionized water added is 3% to 15% of the volume of zirconium n-butoxide. The vacuum filtration is carried out in a vacuum filter, first filtering 3-5 times under alcohol washing conditions, and then filtering 3-5 times under deionized water washing conditions; The drying process is carried out in a vacuum drying oven, the drying time is 8-10 hours, and the drying temperature is 50-60°C; The calcination temperature is 450-550° C., the calcination time is 3.5-4.5 hours, and the powder is naturally cooled to room temperature after calcination and ground with a mortar.

7. The method for preparing the ZrW2O8@ZrO2-Cu double-shell structure powder according to claim 3, characterized in that: In step (3), the acidification treatment refers to soaking the zirconium oxide-coated zirconium tungstate powder in 10wt.% hydrochloric acid for 0.5-1h; the sensitizing solution used for the sensitization treatment is a stannous chloride solution, and the sensitization time is 10-20min; the activation solution used for the activation treatment is a palladium chloride solution, and the activation time is 10-20min; the activated powder is placed in a copper plating solution for copper plating, and an oxidation-reduction reaction occurs to form a dense copper shell structure. After the copper plating is completed, it is first stirred and washed with deionized water for 3-5 times, and then stirred and washed with anhydrous ethanol for 2-3 times; finally, it is dried in a vacuum drying oven at 50-60°C for 2-4h.

8. The method for preparing the ZrW2O8@ZrO2-Cu double-shell structure powder according to claim 7, characterized in that: The stannous chloride solution (sensitizing solution) contains 20 g / L stannous chloride (SnCl2·H2O), 40 ml / L hydrochloric acid (HCl), and the rest is water; The palladium chloride solution (activation solution) contains 0.25 g / L palladium chloride (PdCl2), 2.5 ml / L hydrochloric acid (HCl), and the rest is water; The copper plating solution comprises: 16-20 g / L of copper sulfate pentahydrate (CuSO4·5H2O), 20-25 g / L of potassium sodium tartrate (KnaC4H4O6·4H2O), 25-30 g / L of EDTA-2Na, 12-20 g / L of sodium hydroxide (NaOH), 12-20 ml / L of formaldehyde, and the rest is water.

9. The use of the ZrW2O8@ZrO2-Cu double-shell structure powder according to claim 1 or 2, characterized in that: The ZrW2O8@ZrO2-Cu double-shell structure powder is used in laser cladding and is added to the cladding material used; the double-shell structure powder can better protect the negative thermal expansion of its zirconium tungstate, reduce the loss of zirconium tungstate during cladding and welding, reduce the thermal expansion performance of metal cladding and welding, and thus reduce cracks caused by stress generated in some materials under rapid cooling and heating environments.

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