Aluminum alloy extrusion die containing tungsten carbide, preparation method and application of aluminum alloy extrusion die

Abstract

The invention discloses an aluminum alloy extrusion die containing tungsten carbide and a preparation method and application thereof, and belongs to the technical field of aluminum alloy extrusion die preparation. The preparation method comprises the following steps that steel is prepared, and an extrusion die blank is formed; preparing a surface coating material: 19.5 to 21.4 parts of mullite / LiAlSiO4 co-doped powder on the inner layer, 17.7 to 19.2 parts of CrN / MO2B powder on the middle layer and 24.2 to 25.6 parts of TiN / mullite / LiAlSiO4 co-doped powder on the outer layer; pretreatment of the surface of the extrusion die blank: polishing the surface of the extrusion die blank to remove an oxide layer; a surface coating material is sprayed on the surface of the extrusion die blank after being subjected to hot melting, and the thickness of the surface coating material is controlled to be 5-8 microns; and performing freezing treatment and heat treatment on the extrusion die blank in sequence. The coating is prepared from the mullite / LiAlSiO4 co-doped coating on the inner layer, the CrN / MO2B coating on the middle layer and the TiN / mullite / LiAlSiO4 co-doped coating on the outer layer, the thickness of the coatings is greatly reduced, the wear resistance is good, and the mold has good high-temperature mechanical properties in a high-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy extrusion die preparation, and in particular to an aluminum alloy extrusion die containing tungsten carbide, a preparation method and application thereof. Background Art

[0002] Tungsten carbide powder (WC) is the main raw material for producing cemented carbide. It is a black hexagonal crystal with metallic luster, a hardness similar to that of diamond, and stable chemical properties.

[0003] Aluminum alloy extrusion dies are used to extrude aluminum alloys. They are typically made of steel, which has drawbacks such as low wear resistance. Coatings can be added to these dies to achieve these requirements. For example, CN104388927B discloses a method for preparing a high-hardness coating on an aluminum alloy surface by laser cladding a powder alloy.

[0004] However, in the traditional preparation process, the pre-coating thickness is large, with a drying time of approximately 2-5 hours for a coating of 0.3-0.6 mm. Moreover, the wear resistance of the alloy coating still needs to be further improved, especially in high-temperature environments, where the coating is easily abraded, making it difficult to be applied in the field of aluminum alloy extrusion dies. In addition, the high-temperature mechanical properties of aluminum alloy extrusion dies also need to be further enhanced.

[0005] Based on this, the present invention designs an aluminum alloy extrusion die containing tungsten carbide, a preparation method and application thereof to solve the above problems. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides an aluminum alloy extrusion die containing tungsten carbide, a preparation method and applications thereof.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A method for preparing an aluminum alloy extrusion die containing tungsten carbide comprises the following steps:

[0009] Step 1: Prepare steel and form the extrusion die body;

[0010] Step 2: preparing surface coating material;

[0011] The surface coating material comprises the following raw materials in parts by weight: 19.5 to 21.4 parts of mullite / LiAlSiO4 co-doped powder for the inner layer, 17.7 to 19.2 parts of CrN / MO2B powder for the middle layer, and 24.2 to 25.6 parts of TiN / mullite / LiAlSiO4 co-doped powder for the outer layer;

[0012] Step 3: Pretreatment of the extrusion die body surface: Grinding the surface of the extrusion die body to remove the oxide layer;

[0013] Step 4: After hot melting, the surface coating material is sprayed on the surface of the extrusion die body. The thickness of the surface coating material is controlled to be 5 to 8 microns.

[0014] Step 5: freezing and heat treating the extrusion die blank in sequence;

[0015] The freezing treatment temperature is -10 to 0°C and the holding time is 0.5 to 1 hour;

[0016] The heat treatment temperature is 130-145°C, the holding time is 20-30 minutes, and the heating rate is 4-6°C / min.

[0017] Furthermore, in step 2, in step 1, the steel comprises the following raw materials in weight percentage: C 0.02-0.05%, Si 0.15-0.18%, Mn 0.31-0.56%, Cr 0.01-0.03%, WC 0.24-0.32%, Mo: 0.003-0.005%, Al < 0.001%, Ti 0.001-0.002%, Ni 0.002-0.005%, and the balance is Fe and unavoidable impurities;

[0018] Furthermore, step one also includes performing secondary aging heat treatment on the extrusion die blank, specifically: first keeping it at a temperature of 400-410°C for 0.5-1h, heating rate of 6-8°C / min, and air cooling; then keeping it at a temperature of 200-205°C for 0.5-1h, heating rate of 4-5°C / min, and water cooling.

[0019] Furthermore, in step four, the mullite / LiAlSiO4 co-doped powder is first hot-melted and then sprayed on the surface of the extrusion die blank to form an inner connecting layer; then the CrN / MO2B powder is hot-melted and sprayed on the surface of the inner connecting layer to form a middle transition layer; then the TiN / mullite / LiAlSiO4 co-doped powder is sprayed on the surface of the middle transition layer to form an outer wear-resistant layer.

[0020] Furthermore, the thickness of the inner connecting layer is controlled to be 0.5 to 1 micron; the thickness of the middle transition layer is controlled to be 1.5 to 2 microns; and the thickness of the outer wear-resistant layer is controlled to be 2.5 to 5.5 microns.

[0021] Furthermore, the mullite / LiAlSiO4 co-doped powder is prepared by mixing mullite and LiAlSiO4 in a ratio of 11-12:1.4-1.5, calcining at 200-300°C for 20-30 minutes, and then grinding to 200-300 nm to form mullite / LiAlSiO4 co-doped powder.

[0022] Furthermore, the CrN / MO2B powder is formed by mixing CrN and MO2B in a ratio of 1-2:0.5-1 to form mullite / LiAlSiO4 co-doped powder; the particle size of the CrN / MO2B powder is 300-400 nm.

[0023] Furthermore, the TiN / mullite / LiAlSiO4 co-doped powder is prepared by mixing nano-TiN and mullite / LiAlSiO4 co-doped powder in a ratio of 1-3:8-9.

[0024] In order to better achieve the purpose of the present invention, the present invention also provides an aluminum alloy extrusion die containing tungsten carbide prepared according to the preparation method.

[0025] In order to better achieve the purpose of the present invention, the present invention also provides an application of the preparation method in preparing an aluminum alloy extrusion die containing tungsten carbide.

[0026] Compared with the prior art, the present invention has the following beneficial effects: the coating of the present invention is prepared by adopting an inner layer of mullite / LiAlSiO4 co-doped coating, a middle layer of CrN / MO2B coating and an outer layer of TiN / mullite / LiAlSiO4 co-doped coating, the coating thickness is greatly reduced, and a long drying process is not required. The multi-layer composite coating is beneficial to enhancing the wear resistance of the coating and is beneficial for the mold to have good high-temperature mechanical properties in a high-temperature environment, and can be well applied in the field of extrusion molds. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Example 1: In some embodiments, a method for preparing an aluminum alloy extrusion die containing tungsten carbide comprises the following steps:

[0029] Step 1: Prepare steel and form the extrusion die body;

[0030] The steel material comprises the following raw materials in weight percentage: C 0.02%, Si 0.18%, Mn 0.31%, Cr 0.03%, WC 0.24%, Mo: 0.005%, Al < 0.001%, Ti 0.001%, Ni 0.005%, and the balance is Fe and unavoidable impurities;

[0031] The extrusion die blank was subjected to secondary aging heat treatment, specifically: first, it was kept at 400°C for 1h, the heating rate was 6°C / min, and air-cooled; then it was kept at 205°C for 0.5h, the heating rate was 5°C / min, and water-cooled.

[0032] Step 2: preparing surface coating material;

[0033] The surface coating material comprises the following raw materials in parts by weight: 19.5 parts of mullite / LiAlSiO4 co-doped powder for the inner layer, 19.2 parts of CrN / MO2B powder for the middle layer, and 24.2 parts of TiN / mullite / LiAlSiO4 co-doped powder for the outer layer;

[0034] The mullite / LiAlSiO4 co-doped powder is prepared by mixing mullite and LiAlSiO4 in a ratio of 11:1.5, calcining at 200°C for 30 minutes, and then grinding to 200 nm to form the mullite / LiAlSiO4 co-doped powder.

[0035] The CrN / MO2B powder is formed by mixing CrN and MO2B in a ratio of 1:1 to form mullite / LiAlSiO4 co-doped powder; the particle size of the CrN / MO2B powder is 300nm;

[0036] The TiN / mullite / LiAlSiO4 co-doped powder is prepared by mixing nano-TiN and mullite / LiAlSiO4 co-doped powder in a ratio of 1:9.

[0037] Step 3: Pretreatment of the extrusion die body surface: Grinding the surface of the extrusion die body to remove the oxide layer;

[0038] Step 4: hot-melt the surface coating material and spray it on the surface of the extrusion die blank;

[0039] Specifically, the mullite / LiAlSiO4 co-doped powder is first hot-melted and then sprayed on the surface of the extrusion die blank to form an inner connecting layer; the thickness of the inner connecting layer is controlled to be 0.5 microns;

[0040] Then, CrN / MO2B powder is hot-melted and sprayed on the surface of the inner connecting layer to form a middle transition layer; the thickness of the middle transition layer is controlled at 2 microns;

[0041] Then, TiN / mullite / LiAlSiO4 co-doped powder is sprayed on the surface of the middle transition layer to form an outer wear-resistant layer; the thickness of the outer wear-resistant layer is controlled to be 2.5 microns;

[0042] Step 5: freezing and heat treating the extrusion die blank in sequence;

[0043] The freezing treatment temperature was -10°C and the holding time was 1 h;

[0044] The heat treatment temperature is 130°C, the holding time is 30 min, and the heating rate is 4°C / min.

[0045] Example 2: In some embodiments, a method for preparing an aluminum alloy extrusion die containing tungsten carbide comprises the following steps:

[0046] Step 1: Prepare steel and form the extrusion die body;

[0047] The steel material comprises the following raw materials in percentage by weight: C 0.05%, Si 0.15%, Mn 0.56%, Cr 0.01%, WC 0.32%, Mo: 0.003%, Al < 0.001%, Ti 0.002%, Ni 0.002%, and the balance is Fe and unavoidable impurities;

[0048] The extrusion die blank was subjected to secondary aging heat treatment, specifically: first, it was kept at 410°C for 0.5h, with a heating rate of 8°C / min, and air-cooled; then it was kept at 200°C for 1h, with a heating rate of 4°C / min, and water-cooled.

[0049] Step 2: preparing surface coating material;

[0050] The surface coating material comprises the following raw materials in parts by weight: 21.4 parts of mullite / LiAlSiO4 co-doped powder for the inner layer, 17.7 parts of CrN / MO2B powder for the middle layer, and 25.6 parts of TiN / mullite / LiAlSiO4 co-doped powder for the outer layer;

[0051] The mullite / LiAlSiO4 co-doped powder is prepared by mixing mullite and LiAlSiO4 in a ratio of 12:1.4, calcining at 300°C for 20 minutes, and then grinding to 300 nm to form the mullite / LiAlSiO4 co-doped powder.

[0052] The CrN / MO2B powder is formed by mixing CrN and MO2B in a ratio of 2:0.5 to form mullite / LiAlSiO4 co-doped powder; the particle size of the CrN / MO2B powder is 400nm;

[0053] The TiN / mullite / LiAlSiO4 co-doped powder is prepared by mixing nano-TiN and mullite / LiAlSiO4 co-doped powder in a ratio of 3:8.

[0054] Step 3: Pretreatment of the extrusion die body surface: Grinding the surface of the extrusion die body to remove the oxide layer;

[0055] Step 4: hot-melt the surface coating material and spray it on the surface of the extrusion die blank;

[0056] Specifically, the mullite / LiAlSiO4 co-doped powder is first hot-melted and then sprayed on the surface of the extrusion die blank to form an inner connecting layer; the thickness of the inner connecting layer is controlled to be 1 micron;

[0057] Then, CrN / MO2B powder is hot-melted and sprayed on the surface of the inner connecting layer to form a middle transition layer; the thickness of the middle transition layer is controlled at 1.5 microns;

[0058] Then, TiN / mullite / LiAlSiO4 co-doped powder is sprayed on the surface of the middle transition layer to form an outer wear-resistant layer; the thickness of the outer wear-resistant layer is controlled at 5.5 microns;

[0059] Step 5: freezing and heat treating the extrusion die blank in sequence;

[0060] The freezing treatment temperature was 0°C and the holding time was 0.5 h;

[0061] The heat treatment temperature is 145°C, the holding time is 20 min, and the heating rate is 6°C / min.

[0062] Example 3: In some embodiments, a method for preparing an aluminum alloy extrusion die containing tungsten carbide comprises the following steps:

[0063] Step 1: Prepare steel and form the extrusion die body;

[0064] The steel material comprises the following raw materials in percentage by weight: C 0.03%, Si 0.17%, Mn 0.42%, Cr 0.02%, WC 0.30%, Mo: 0.004%, Al < 0.001%, Ti 0.001%, Ni 0.004%, and the balance is Fe and unavoidable impurities;

[0065] The extrusion die blank was subjected to secondary aging heat treatment, specifically: first, it was kept at 403°C for 0.6h, the heating rate was 7°C / min, and air-cooled; then it was kept at 202°C for 0.6h, the heating rate was 4.5°C / min, and water-cooled.

[0066] Step 2: preparing surface coating material;

[0067] The surface coating material comprises the following raw materials in parts by weight: 20.6 parts of mullite / LiAlSiO4 co-doped powder for the inner layer, 18.4 parts of CrN / MO2B powder for the middle layer, and 25.1 parts of TiN / mullite / LiAlSiO4 co-doped powder for the outer layer;

[0068] The mullite / LiAlSiO4 co-doped powder is prepared by mixing mullite and LiAlSiO4 in a ratio of 11.2:1.4, calcining at 220° C. for 25 minutes, and then grinding to 250 nm to form the mullite / LiAlSiO4 co-doped powder.

[0069] The CrN / MO2B powder is formed by mixing CrN and MO2B in a ratio of 1.3:0.6 to form mullite / LiAlSiO4 co-doped powder; the particle size of the CrN / MO2B powder is 350nm;

[0070] The TiN / mullite / LiAlSiO4 co-doped powder is prepared by mixing nano-TiN and mullite / LiAlSiO4 co-doped powder in a ratio of 2:8.8.

[0071] Step 3: Pretreatment of the extrusion die body surface: Grinding the extrusion die body surface to remove the oxide layer;

[0072] Step 4: hot-melt the surface coating material and spray it on the surface of the extrusion die blank;

[0073] Specifically, the mullite / LiAlSiO4 co-doped powder is first hot-melted and then sprayed on the surface of the extrusion die blank to form an inner connecting layer; the thickness of the inner connecting layer is controlled to be 0.6 microns;

[0074] Then, CrN / MO2B powder is hot-melted and sprayed on the surface of the inner connecting layer to form a middle transition layer; the thickness of the middle transition layer is controlled at 1.6 microns;

[0075] Then, TiN / mullite / LiAlSiO4 co-doped powder is sprayed on the surface of the middle transition layer to form an outer wear-resistant layer; the thickness of the outer wear-resistant layer is controlled at 4.8 microns;

[0076] Step 5: freezing and heat treating the extrusion die blank in sequence;

[0077] The freezing treatment temperature was -5°C and the holding time was 0.6h;

[0078] The heat treatment temperature is 137°C, the holding time is 25 min, and the heating rate is 5.5°C / min.

[0079] The performance test of the extrusion die is as follows: hardness 1105HV, tensile strength 1050MPa, compressive strength 1850MPa, high temperature tensile strength at 300°C 925MPa, high temperature compressive strength 1800MPa.

[0080] The coating of the present invention is prepared by adopting an inner layer of mullite / LiAlSiO4 co-doped coating, a middle layer of CrN / MO2B coating and an outer layer of TiN / mullite / LiAlSiO4 co-doped coating. The coating thickness is greatly reduced and a long drying process is not required. The multi-layer composite coating is beneficial to enhancing the wear resistance of the coating and is beneficial for the mold to have good high-temperature mechanical properties in a high-temperature environment. It can be well applied in the field of extrusion molds.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing an aluminum alloy extrusion die containing tungsten carbide, characterized in that: The following steps are involved: Step 1: Prepare steel and form the extrusion die body; Step 2: preparing surface coating material; The surface coating material comprises the following raw materials in parts by weight: 19.5 to 21.4 parts of mullite / LiAlSiO4 co-doped powder for the inner layer, 17.7 to 19.2 parts of CrN / MO2B powder for the middle layer, and 24.2 to 25.6 parts of TiN / mullite / LiAlSiO4 co-doped powder for the outer layer; Step 3: Pretreatment of the extrusion die body surface: Grinding the extrusion die body surface to remove the oxide layer; Step 4: After hot melting, the surface coating material is sprayed on the surface of the extrusion die blank. The thickness of the surface coating material is controlled to be 5 to 8 microns. Step 5: freezing and heat treating the extrusion die blank in sequence; The freezing treatment temperature is -10 to 0°C and the holding time is 0.5 to 1 hour; The heat treatment temperature is 130-145°C, the holding time is 20-30 minutes, and the heating rate is 4-6°C / min.

2. The method for preparing an aluminum alloy extrusion die containing tungsten carbide according to claim 1, wherein: In step 2, in step 1, the steel comprises the following raw materials in weight percentage: C 0.02-0.05%, Si 0.15-0.18%, Mn 0.31-0.56%, Cr 0.01-0.03%, WC 0.24-0.32%, Mo: 0.003-0.005%, Al<0.001%, Ti 0.001-0.002%, Ni 0.002-0.005%, and the balance is Fe and unavoidable impurities.

3. The method for preparing an aluminum alloy extrusion die containing tungsten carbide according to claim 1, wherein: Step one also includes performing secondary aging heat treatment on the extrusion die blank, specifically: first, keep it at a temperature of 400-410°C for 0.5-1h, with a heating rate of 6-8°C / min, and air cooling; then keep it at a temperature of 200-205°C for 0.5-1h, with a heating rate of 4-5°C / min, and water cooling.

4. The method for preparing an aluminum alloy extrusion die containing tungsten carbide according to claim 1, wherein: In step four, the mullite / LiAlSiO4 co-doped powder is first hot-melted and then sprayed on the surface of the extrusion die blank to form an inner connecting layer; then the CrN / MO2B powder is hot-melted and sprayed on the surface of the inner connecting layer to form a middle transition layer; then the TiN / mullite / LiAlSiO4 co-doped powder is sprayed on the surface of the middle transition layer to form an outer wear-resistant layer.

5. The method for preparing an aluminum alloy extrusion die containing tungsten carbide according to claim 4, wherein: The thickness of the inner connecting layer is controlled to be 0.5 to 1 micron; the thickness of the middle transition layer is controlled to be 1.5 to 2 microns; and the thickness of the outer wear-resistant layer is controlled to be 2.5 to 5.5 microns.

6. The method for preparing an aluminum alloy extrusion die containing tungsten carbide according to claim 1, wherein: The mullite / LiAlSiO4 co-doped powder is prepared by mixing mullite and LiAlSiO4 in a ratio of 11-12:1.4-1.5, calcining at 200-300°C for 20-30 minutes, and then grinding the mixture to 200-300 nm to form the mullite / LiAlSiO4 co-doped powder.

7. The method for preparing an aluminum alloy extrusion die containing tungsten carbide according to claim 1, wherein: The CrN / MO2B powder is prepared by mixing CrN and MO2B in a ratio of 1-2:0.5-1 to form mullite / LiAlSiO4 co-doped powder; the particle size of the CrN / MO2B powder is 300-400nm.

8. The method for preparing an aluminum alloy extrusion die containing tungsten carbide according to claim 1, wherein: The TiN / mullite / LiAlSiO4 co-doped powder is prepared by mixing nano-TiN and mullite / LiAlSiO4 co-doped powder in a ratio of 1-3:8-9.

9. An aluminum alloy extrusion die containing tungsten carbide prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the preparation method according to any one of claims 1 to 8 in preparing an aluminum alloy extrusion die containing tungsten carbide.