Protective coating for mold and preparation method thereof, powder material, and die-casting mold

Abstract

In order to overcome the problem of high-temperature aluminum liquid eroding the mold during the die-casting process, the present invention provides a protective coating for the mold, the protective coating comprising the following elemental components by mass percentage: Mn content is 2%-9%, Cr content is 15%-20%, B content is 6%-12%, Si content is 1%-5%, Mo content is 44%-52%, Fe content is 2%~32%, and the total amount of other elements is less than 0.1%. At the same time, the present invention also discloses a preparation method, powder material and die-casting mold of the above-mentioned protective coating. The protective coating provided by the present invention can effectively avoid the problem of aluminum liquid sticking to the mold body during the die-casting process, avoids the erosion of aluminum liquid on the mold body, and has excellent wear resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of metal materials, and in particular relates to a protective coating for a mold and a preparation method thereof, a powder material, and a die-casting mold. Background Art

[0002] In the process of aluminum alloy die-casting, the working environment of the mold is harsh. The pouring temperature of the aluminum alloy melt is usually between 670 and 790°C, the gate speed is 30 to 60 m / s, and the pressure is 20 to 120 MPa. The cavity surface is corroded by the high temperature and high-speed erosion of the molten metal. Therefore, during the long-term use, the mold surface is corroded and peeled off, thermal fatigue cracks, and other defects lead to mold failure. The more common treatment method is to perform nitriding treatment on the mold surface or prepare a coating on its surface to protect the mold, thereby increasing the mold life.

[0003] There is an existing type of mold surface protective coating, which is prepared by mixing high entropy alloy and ceramic particles. The ceramic particles are added secondary, which is easy to introduce impurities, uneven distribution, and no guarantee of ceramic-metal interface bonding, which in turn affects the protective effect of the coating on the mold. The composite addition requires a high degree of uniformity, and has high requirements for equipment and processes.

[0004] There is another type of alloy material as the existing technology for protective coating. However, this type of alloy protective coating is mainly an amorphous structure and still has the problem of insufficient impact resistance. At the same time, it also fails to avoid the adhesion of aluminum liquid. Summary of the invention

[0005] In order to solve the problem of mold erosion by high-temperature aluminum liquid during die-casting, the present invention provides a protective coating for the mold and a preparation method thereof, a powder material, and a die-casting mold.

[0006] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0007] In one aspect, the present invention provides a protective coating for a mold, wherein the protective coating comprises the following elemental components in percentage by mass:

[0008] The content of Mn is 2%-9%, the content of Cr is 15%-20%, the content of B is 6%-12%, the content of Si is 1%-5%, the content of Mo is 44%-52%, the content of Fe is 2% to 32%, and the total amount of other elements is less than 0.1%.

[0009] Optionally, the protective coating comprises the following elemental components in mass percentage:

[0010] The content of Mn is 4%-7%, the content of Cr is 15%-20%, the content of B is 10%-12%, the content of Si is 1%-3%, the content of Mo is 47%-50%, the content of Fe is 8%~23%, and the total amount of other elements is less than 0.1%.

[0011] Optionally, the protective coating includes a metal matrix and a ceramic reinforcement phase in-situ formed in the metal matrix, the metal matrix includes a solid solution of Fe, and the ceramic reinforcement phase includes Mo2FeB2 and (MoCrFe)3B2.

[0012] Optionally, the ceramic reinforcement phase further includes one or more of Fe2B, Cr2B3 and MoB.

[0013] Optionally, Cr, Mo and Mn are dissolved in the solid solution of Fe.

[0014] Optionally, in the protective coating, the molar ratio of Mo to B is 0.3 to 0.9:1.

[0015] In another aspect, the present invention provides a powder material for preparing the protective coating for a mold as described above, comprising a mixture of Fe element and / or Fe alloy powder, Mn element and / or Mn alloy powder, Cr element and / or Cr alloy powder, B element and / or B alloy powder, Si element and / or Si alloy powder, Mo element and / or Mo alloy powder, wherein each element satisfies the following element composition in mass percentage:

[0016] The content of Mn is 2%-9%, the content of Cr is 15%-20%, the content of B is 6%-12%, the content of Si is 1%-5%, the content of Mo is 44%-52%, the content of Fe is 2% to 32%, and the total amount of other elements is less than 0.1%.

[0017] Optional powders include Fe powder, ferromolybdenum alloy powder, ferroboron alloy powder, ferrochrome alloy powder, silicon powder and ferromanganese alloy powder.

[0018] In another aspect, the present invention provides a die-casting mold, comprising a mold body and the mold protective coating as described above, wherein the protective coating is formed on a surface of the mold body.

[0019] Optionally, the die-casting mold is a steel mold.

[0020] Optionally, the die-casting mold is an aluminum alloy die-casting mold.

[0021] In another aspect, the present invention provides a method for preparing the protective coating for a mold as described above, comprising the following operations:

[0022] Preparing powders containing Fe and / or Fe alloy, Mn and / or Mn alloy, Cr and / or Cr alloy, B and / or B alloy, Si and / or Si alloy, and Mo and / or Mo alloy respectively and mixing them to obtain a powder material;

[0023] The powder material comprises the following elemental components in mass percentage:

[0024] The content of Mn is 2%-9%, the content of Cr is 15%-20%, the content of B is 6%-12%, the content of Si is 1%-5%, the content of Mo is 44%-52%, the content of Fe is 2% to 32%, and the total amount of other elements is less than 0.1%;

[0025] The powder material is melted and covered on the mold body. During the cladding process, the Fe element forms a solid solution, and the B element, Fe, Mo, and Gr in the solid solution in situ synthesize a ceramic reinforcement phase, and a protective coating is obtained after cooling.

[0026] Optionally, the powder material is prepared by an atomization method.

[0027] Optionally, the powder material is melted and covered on the mold body by plasma cladding or laser cladding to form a protective coating.

[0028] According to the protective coating for molds provided by the present invention, Fe element is used as a matrix. Through the adjustment and coordination of various elements, when the protective coating is melt-coated on the surface of the mold, a protective coating with high compatibility with the steel mold body can be formed, thereby ensuring the bonding strength between the protective coating and the mold body, and the protective coating has good impact resistance and wear resistance. When the protective coating contacts with aluminum liquid, it has good erosion resistance to dynamic aluminum liquid, and no additional ceramic powder is required. The reinforcing phase formed by itself has low wettability with aluminum liquid, which effectively avoids the problem of aluminum liquid sticking to the mold body during the die-casting process, and avoids the erosion effect of aluminum liquid on the mold body. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] An embodiment of the present invention provides a protective coating for a mold, wherein the protective coating comprises the following element components in mass percentage:

[0031] The content of Mn is 2%-9%, the content of Cr is 15%-20%, the content of B is 6%-12%, the content of Si is 1%-5%, the content of Mo is 44%-52%, the content of Fe is 2% to 32%, and the total amount of other elements is less than 0.1%.

[0032] In a preferred embodiment, the protective coating comprises the following elemental components in mass percentage:

[0033] The content of Mn is 4%-7%, the content of Cr is 15%-20%, the content of B is 10%-12%, the content of Si is 1%-3%, the content of Mo is 47%-50%, the content of Fe is 8%~23%, and the total amount of other elements is less than 0.1%.

[0034] In a specific embodiment, the Mn content can be selected from 2%, 2.2%, 2.4%, 2.7%, 3.1%, 3.3%, 3.7%, 4%, 4.3%, 4.8%, 5.1%, 5.5%, 5.7%, 6%, 6.4%, 6.9%, 7%, 7.5%, 8%, 8.2%, 8.6% or 9%; the Cr content can be selected from 15%, 16%, 17%, 18%, 19% or 20%; the B content can be selected from 6%, 6.4%, 6.9%, 7.5%, 8%, 8.2%, 8.6% or 9%. %, 6.9%, 7%, 7.5%, 8%, 8.2%, 8.6%, 9%, 9.5%, 10%, 10.3%, 10.9%, 11%, 11.2%, 11.4%, 11.7% or 12%; the Si content can be selected from 1%, 1.3%, 1.9%, 2.1%, 2.2%, 2.4%, 2.7%, 3%, 3.3%, 3.7%, 4%, 4.3%, 4.8% or 5%; the Mo content can be selected from 44%-52%

[0035] The protective coating for the mold uses Fe element as a matrix. Through the adjustment and coordination of various elements, when the protective coating is melt-coated on the surface of the mold, it can form a protective coating with high compatibility with the steel mold body, thereby ensuring the bonding strength between the protective coating and the mold body, and the protective coating has good impact resistance and wear resistance. When the protective coating contacts with aluminum liquid, it has good erosion resistance to dynamic aluminum liquid, and does not require additional ceramic powder. The reinforcing phase formed by itself has low wettability with aluminum liquid, effectively avoiding the problem of aluminum liquid sticking to the mold body during the die-casting process, and avoiding the erosion effect of aluminum liquid on the mold body.

[0036] In the material involved in the present invention, Fe, as the main element in the protective coating, is the aggregate of the protective coating, supports the harder and brittle ceramic reinforcement phase in the protective coating, ensures the toughness of the protective coating and the bonding strength between the protective coating and the steel mold body.

[0037] Mn can transform the needle-shaped FeAl3 into flocculent (Fe, Mn)Al3, which plays a metamorphic role and improves the erosion of the coating by the Al liquid.

[0038] Cr fills the crystallographic vacancies of Fe2Al5 to a certain extent, hinders the mutual diffusion between Fe atoms in the Fe matrix and Al atoms in the aluminum liquid, and improves the resistance to high-temperature oxidation. However, when the Cr content is too high, the matrix will produce too much brittle phase network distributed on the matrix, making the matrix toughness poor.

[0039] Si is used to lower the melting point of alloy powder to facilitate cladding; it can occupy the crystallographic vacancies in Fe2Al5, hinder the mutual diffusion of Fe and Al, and improve the resistance to Al liquid erosion, but too much Si will make the coating more brittle.

[0040] B is used to lower the melting point of the alloy powder. It is the main element for forming the boride ceramic phase, part of which forms the ternary boride M3B2 and part of which forms M2B. The B content can determine the amount of the ceramic strengthening phase in the coating.

[0041] When the B content is too low, there is less ceramic reinforcement phase in the protective coating, the hardness of the protective coating is low, and the wear resistance of the coating is insufficient.

[0042] When the B content is too high, the ceramic reinforcement phase in the protective coating is segregated, making the performance of the protective coating uneven. The areas where the ceramic reinforcement phase is concentrated are easily peeled off from the mold body during use due to the lack of metal base protection around them.

[0043] Mo is used to form a ceramic reinforcement phase. When the Mo content is too low, the number and size of the ceramic reinforcement phase in the protective coating are small, making it difficult to strengthen the protective coating; excessive Mo will increase the melting point of the powder, which is not conducive to the melting of the powder, and excessive Mo will make the size of the ceramic reinforcement phase too large, which will deteriorate the strengthening effect and make the protective coating prone to cracking.

[0044] It should be noted that, in the protective coating, each element does not act alone, but has an associated effect. The increase or decrease of any element may lead to a change in the effect of other elements, thereby causing a change in the overall performance of the protective coating. The relationship between the elements in the present invention is further described below through specific embodiments:

[0045] In some embodiments, the protective coating includes a metal matrix and a ceramic reinforcement phase in-situ formed in the metal matrix, the metal matrix includes a solid solution of Fe, and the ceramic reinforcement phase includes Mo2FeB2 and (MoCrFe)3B2.

[0046] Among them, Mo2FeB2 is a hard ceramic reinforcement phase, and (MoCrFe)3B2 is another ceramic reinforcement phase formed by introducing Cr atoms into the Mo2FeB2 phase to replace Mo atoms and Fe atoms in the crystal. Compared with amorphous alloys, these two ceramic reinforcement phases can effectively improve the hardness of the protective coating, enhance its wear resistance, reduce the wettability of the protective coating with aluminum liquid, and do not react with aluminum liquid. Compared with the form of doping ceramic powder in the alloy, the ceramic reinforcement phase in the protective coating is a thermodynamically stable phase in which each element nucleates and grows in situ in the coating, which can avoid the problem of poor compatibility with the mold body and ensure the adhesion strength of the protective coating on the surface of the mold body.

[0047] Using the solid solution of Fe as the metal matrix can support the ceramic reinforcement phase with higher hardness and meet the toughness requirements of the die casting for the mold body; and the Fe matrix and the mold steel have similar thermal expansion coefficients, so that during the use of the protective coating, it is not easy to produce thermal fatigue cracks caused by cyclic stress at the protective coating-mold body interface, thereby improving the life of the protective coating.

[0048] In some embodiments, the ceramic reinforcement phase further includes one or more of Fe2B, Cr2B3 and MoB.

[0049] Fe2B, Cr2B3 and MoB are binary borides used to improve the erosion resistance of the protective coating to molten aluminum.

[0050] In some embodiments, Cr, Mo and Mn are dissolved in the solid solution of Fe.

[0051] By dissolving Cr, Mo and Mn in Fe, the strength of the metal matrix is ​​improved while also having a certain erosion resistance to aluminum liquid.

[0052] In some embodiments, in the protective coating, the molar ratio of Mo to B is 0.3 to 0.9:1.

[0053] Through further experiments, the inventors found that there is a strong correlation between Mo and B. When Mo and B are in the above-mentioned molar ratio, they are more conducive to combining with each other to form a ternary boride ceramic phase M3B2 of Mo2FeB2 (part of the Mo element will be replaced by Fe and Cr), which is beneficial to further enhance the wear resistance and erosion resistance of the protective coating.

[0054] Another embodiment of the present invention provides a powder material for preparing the protective coating for the mold as described above, comprising a mixture of Fe element and / or Fe alloy powder, Mn element and / or Mn alloy powder, Cr element and / or Cr alloy powder, B element and / or B alloy powder, Si element and / or Si alloy powder, Mo element and / or Mo alloy powder, wherein each element satisfies the following element composition in mass percentage:

[0055] The content of Mn is 2%-9%, the content of Cr is 15%-20%, the content of B is 6%-12%, the content of Si is 1%-5%, the content of Mo is 44%-52%, the content of Fe is 2% to 32%, and the total amount of other elements is less than 0.1%.

[0056] In a preferred embodiment, the powder material includes Fe powder, molybdenum-iron alloy powder, boron-iron alloy powder, chromium-iron alloy powder, silicon powder and manganese-iron alloy powder.

[0057] Another embodiment of the present invention provides a die-casting mold, comprising a mold body and the mold protective coating as described above, wherein the protective coating is formed on the surface of the mold body.

[0058] In some embodiments, the die casting mold is a steel mold.

[0059] The protective coating has good compatibility with the steel mold and a consistent thermal expansion coefficient. When the protective coating is applied to the steel mold, it has good bonding strength and anti-wear effects.

[0060] In some embodiments, the die-casting mold is an aluminum alloy die-casting mold.

[0061] The protective coating has poor wettability with Al liquid, which can effectively prevent the Al liquid from corroding the mold body.

[0062] Another embodiment of the present invention provides a method for preparing the protective coating for a mold as described above, comprising the following operations:

[0063] Preparing powders containing Fe and / or Fe alloy, Mn and / or Mn alloy, Cr and / or Cr alloy, B and / or B alloy, Si and / or Si alloy, and Mo and / or Mo alloy respectively and mixing them to obtain a powder material;

[0064] The powder material comprises the following elemental components in mass percentage:

[0065] The content of Mn is 2%-9%, the content of Cr is 15%-20%, the content of B is 6%-12%, the content of Si is 1%-5%, the content of Mo is 44%-52%, the content of Fe is 2% to 32%, and the total amount of other elements is less than 0.1%;

[0066] The surface of the powder material is clad on the mold body. During the cladding process, the Fe element forms a solid solution, and the B element, Fe, Mo, and Gr in the solid solution in situ synthesize a ceramic reinforcement phase, and a protective coating is obtained after cooling.

[0067] In some embodiments, the powder material can be prepared by existing methods.

[0068] Specifically, the powder material can be prepared by a mechanical method or a physical and chemical method.

[0069] The mechanical method is a processing method that uses mechanical external force to break metal into powder of the desired particle size. The chemical composition of the material remains basically unchanged during the preparation process of this method, and includes ball milling, grinding, and atomization.

[0070] The ball milling method is mainly divided into the rolling ball method and the vibration ball milling method. This method utilizes the mechanism that metal particles are strained and broken and refined at different strain rates.

[0071] The grinding method is to spray compressed gas into the grinding area after passing through a special nozzle, thereby driving the materials in the grinding area to collide with each other and rub into powder; after the air flow expands, it rises with the material into the classification area, and the turbine classifier selects the material that reaches the particle size, and the remaining coarse powder returns to the grinding area for further grinding until it reaches the required particle size and is separated.

[0072] The atomization method generally uses high-pressure gas, high-pressure liquid or high-speed rotating blades to break the metal or alloy melted at high temperature and high pressure into fine droplets, and then condense in the collector to obtain ultrafine metal powder. This process does not cause chemical changes. The atomization method includes double-flow atomization, centrifugal atomization, multi-stage atomization, ultrasonic atomization technology, close-coupled atomization technology, high-pressure gas atomization, laminar atomization, ultrasonic close-coupled atomization and hot gas atomization.

[0073] The physical-chemical method refers to a production method of ultrafine powder obtained by changing the chemical composition or aggregation state of the raw materials during the powder preparation process. According to different chemical principles, it can be divided into reduction method, electrolysis method and chemical replacement method.

[0074] In some embodiments, the powder material is prepared by atomization.

[0075] In some embodiments, plasma cladding or laser cladding is used to melt the powder material and cover the mold body to form a protective coating.

[0076] When plasma cladding is used to prepare the protective coating, the powder material is instantly heated and accelerated to form a particle beam after entering the plasma beam. The particles are in a molten or semi-molten state and are sprayed onto the mold body to be processed. Physical and chemical changes such as melting, mixing, and solidification occur on the surface of the mold body, and finally the particles are metallurgically bonded to the surface of the mold body.

[0077] Laser cladding refers to placing selected powder materials on the surface of the mold body in different ways, irradiating them with laser to melt them and a thin layer on the surface of the mold body at the same time, and then quickly solidifying to form a surface coating with extremely low dilution and metallurgical bonding with the mold body.

[0078] The present invention is further described below by way of examples.

[0079] Table 1

[0080]

[0081]

[0082] Example 1

[0083] This embodiment is used to illustrate the protective coating, die-casting mold and preparation method thereof disclosed in the present invention, and includes the following operations:

[0084] Step 1: As shown in Table 1, Fe powder, molybdenum-iron alloy powder, boron-iron alloy powder, chromium-iron alloy powder, silicon powder and manganese-iron alloy powder are weighed respectively, wherein the content of each element is calculated by mass content: Mn content is 5%, Cr content is 17%, B content is 11%, Si content is 2%, Mo content is 48%, and the balance is Fe. The mass of various required master alloys or single substances is calculated according to the mass content of the elements, and the balance is Fe powder and unavoidable impurities, and the impurity content is less than 0.1%.

[0085] Step 2: Mix Fe powder, molybdenum-iron alloy powder, boron-iron alloy powder, chromium-iron alloy powder, silicon powder and manganese-iron alloy powder, and stir evenly to form a powder material.

[0086] Step 3: The powder material is fed into a plasma cladding machine, and the plasma carries the powder material to the surface of the steel mold for die-casting aluminum to obtain a die-casting mold with a protective coating formed on the surface.

[0087] Embodiments 2 to 18

[0088] Examples 2-18 are used to illustrate the protective coating, die-casting mold and preparation method thereof disclosed in the present invention, and include most of the operating steps in Example 1, except that:

[0089] The elemental components shown in Examples 2-18 in Table 1 were used, and the other operating steps were the same as those in Example 1.

[0090] Comparative Examples 1-10

[0091] Comparative Examples 1-10 are used to compare and illustrate the protective coating, die-casting mold and preparation method thereof disclosed in the present invention, including most of the operating steps in Example 1, except that:

[0092] The element components shown in Comparative Examples 1-10 in Table 1 were used, and the other operating steps were the same as those in Example 1.

[0093] Comparative Example 11

[0094] Comparative Example 11 is used to compare and illustrate the protective coating, die-casting mold and preparation method thereof disclosed in the present invention, and includes most of the operation steps in Example 1, except that:

[0095] The boron element in the powder material is added in the form of Mo2FeB2 ceramic powder. Specifically, Fe powder, molybdenum-iron alloy powder, Mo2FeB2 ceramic powder, chromium-iron alloy powder, silicon powder and manganese-iron alloy powder are mixed and stirred evenly to form a powder material.

[0096] Performance Testing

[0097] The die-casting mold prepared above was subjected to the following performance tests:

[0098] Erosion test: Weigh the die-casting mold and record the initial weight M1. Place the die-casting mold in aluminum liquid and immerse and rotate it at a speed of 300r / min. The aluminum liquid temperature is 710℃ and the immersion time is 10min. Take out the die-casting mold, immerse it in NaOH solution, weigh and record the weight after erosion M2. Calculate the remaining mass ratio of the mold after erosion according to the following formula:

[0099]

[0100] Hardness test: Take several places on the surface of the die-casting mold for Vickers hardness test, and calculate the average value of the surface Vickers hardness.

[0101] The test results obtained are entered in Table 2.

[0102] Table 2

[0103]

[0104] It can be seen from the test results in Table 2 that the protective coating provided by the present invention can protect the mold body during the aluminum die-casting process, and the protective coating has better wear resistance and erosion resistance, effectively improving the service life of the die-casting mold.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A protective coating for a mold, characterized in that: The protective coating comprises the following elemental components in mass percentage: The content of Mn is 2%-9%, the content of Cr is 15%-20%, the content of B is 6%-12%, the content of Si is 1%-5%, the content of Mo is 44%-52%, the content of Fe is 2% to 32%, and the total amount of other elements is less than 0.1%.

2. The protective coating for mold according to claim 1, characterized in that: The protective coating comprises the following elemental components in mass percentage: The content of Mn is 4%-7%, the content of Cr is 15%-20%, the content of B is 10%-12%, the content of Si is 1%-3%, the content of Mo is 47%-50%, the content of Fe is 8% to 23%, and the total amount of the other elements is less than 0.1%.

3. The protective coating for mold according to claim 1, characterized in that: The protective coating includes a metal matrix and a ceramic reinforcement phase in-situ formed in the metal matrix, wherein the metal matrix includes a solid solution of Fe, and the ceramic reinforcement phase includes Mo2FeB2 and (MoCrFe)3B2.

4. The protective coating for mold according to claim 3, characterized in that: The ceramic reinforcement phase further includes one or more of Fe2B, Cr2B3 and MoB, and Cr, Mo and Mn are dissolved in the solid solution of Fe.

5. The protective coating for mold according to claim 1, characterized in that: In the protective coating, the molar ratio of Mo to B is 0.3-0.9:

1.

6. A powder material for preparing a protective coating for a mold as claimed in any one of claims 1 to 5, characterized in that: A mixture comprising Fe single substance and / or Fe alloy powder, Mn single substance and / or Mn alloy powder, Cr single substance and / or Cr alloy powder, B single substance and / or B alloy powder, Si single substance and / or Si alloy powder, Mo single substance and / or Mo alloy powder, wherein each element satisfies the following element composition in mass percentage: The content of Mn is 2%-9%, the content of Cr is 15%-20%, the content of B is 6%-12%, the content of Si is 1%-5%, the content of Mo is 44%-52%, the content of Fe is 2% to 32%, and the total amount of other elements is less than 0.1%.

7. The powder material according to claim 6, characterized in that: Including Fe powder, molybdenum-iron alloy powder, boron-iron alloy powder, chromium-iron alloy powder, silicon powder and manganese-iron alloy powder.

8. A die-casting mold, characterized in that: The invention comprises a mold body and a protective coating for the mold according to any one of claims 1 to 5, wherein the protective coating is formed on the surface of the mold body.

9. The die-casting mold according to claim 8, characterized in that: The die-casting mold is a steel mold and / or an aluminum alloy die-casting mold.

10. The method for preparing a protective coating for a mold according to any one of claims 1 to 5, characterized in that: The following operations are included: Preparing powders containing Fe and / or Fe alloy, Mn and / or Mn alloy, Cr and / or Cr alloy, B and / or B alloy, Si and / or Si alloy, and Mo and / or Mo alloy respectively and mixing them to obtain a powder material; The powder material comprises the following elemental components in mass percentage: The content of Mn is 2%-9%, the content of Cr is 15%-20%, the content of B is 6%-12%, the content of Si is 1%-5%, the content of Mo is 44%-52%, the content of Fe is 2% to 32%, and the total amount of other elements is less than 0.1%; The surface of the powder material is clad on the mold body. During the cladding process, the Fe element forms a solid solution, and the B element, Fe, Mo, and Gr in the solid solution in situ synthesize a ceramic reinforcement phase, and a protective coating is obtained after cooling.

11. The preparation method according to claim 10, characterized in that: The powder material is prepared by an atomization method.

12. The preparation method according to claim 10, characterized in that: The powder material is melted and covered on the mold body by plasma cladding or laser cladding to form a protective coating.

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