Wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN and production process thereof

Abstract

The invention relates to the technical field of titanium-cobalt alloy production, in particular to a wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN and a production process thereof.The wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN comprises raw materials including pig iron powder, titanium carbide, cobalt powder, chromium carbide, tungsten carbide, copper-zinc composite powder and rare earth metal powder, an additive including 9ALC, 5USCBN and rare earth elements of yttrium and cerium, TiC and USCBN serve as hard reinforcing phases, and the raw materials are made of stainless steel. And the materials are uniformly distributed in a titanium matrix, so that the hardness and wear resistance of the alloy are remarkably improved. The hardness of TiC can reach 3000 HV, the hardness of USCBN can reach 4000 HV, so that the alloy can bear a high-abrasion environment, the brittleness problem caused by hard phase aggregation is avoided by controlling the particle size and distribution of TiC and USCBN, meanwhile, the toughness of the alloy is kept, and the corrosion resistance and surface hardness of the alloy can be further improved through the two-time smelting and PVD surface treatment mode and the TiN coating, so that the corrosion resistance and surface hardness of the alloy are improved. And the alloy can be subjected to surface treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium cobalt alloy production, and particularly relates to a wear-resistant, heat-resistant and corrosion-resistant titanium cobalt alloy TiC-9ALC-5USCBN and its production process. Background Art

[0002] There are many high-temperature wear conditions in industries such as thermal power generation and petrochemical industry. For example, the wind caps, central cylinders, etc. in the fluidized bed boilers of thermal power plants. Under such conditions, during use, it is necessary to withstand the high-temperature oxidation effect of 950 - 1150 °C, and at the same time withstand the severe impact wear of pulverized coal and ash slag; it has to withstand both high temperature and wear, and the consumption of accessories is very serious; many heat-resistant steels currently in use, such as heat-resistant steels represented by ZG25Cr20Ni14Si2, ZG40Cr25Ni12Si2, ZG40Cr25Ni20Si2, etc. These high-alloy steels have high oxidation resistance and good high-temperature resistance, and are widely used in thermal power plants across the country.

[0003] However, traditional titanium alloys (such as Ti-6Al-4V) still have limitations in extreme environments, such as high temperature, high wear and strong corrosive media. For example, at high temperatures, the oxidation resistance and strength of titanium alloys will decrease significantly; in high-wear environments, their surface hardness is insufficient and they are prone to wear; in strong acids, strong alkalis or chlorine-containing media, their corrosion resistance will also be challenged. Specifically, thermal power generating units frequently perform peak shaving and operate at low loads. At this time, some burners in the upper part of the boiler are in a shutdown state, resulting in dry burning damage to burner components (nozzles, etc.) and the fixing devices (pipe clamps) of the boiler superheater tube screens. Therefore, higher requirements are placed on the high-temperature resistance and dry-burning resistance of their materials. In addition, heat-resistant steels (nozzles, wind caps) used in high-temperature impact wear conditions have poor wear resistance. Summary of the Invention

[0004] Technical Problems to be Solved

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a wear-resistant, heat-resistant and corrosion-resistant titanium cobalt alloy TiC-9ALC-5USCBN and its production process, which can effectively solve the problems in the prior art.

[0006] Technical Solutions

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

[0008] The present invention provides a wear-resistant, heat-resistant and corrosion-resistant titanium cobalt alloy TiC-9ALC-5USCBN, including; raw materials, including pig iron powder, titanium carbide, cobalt powder, chromium carbide, tungsten carbide, copper-zinc composite powder and rare earth metal powder, additives, including 9ALC, 5USCBN and yttrium and cerium rare earth elements.

[0009] Furthermore, in the raw materials, by weight: 60 - 80 parts of pig iron powder, 20 - 25 parts of tungsten carbide, 10 - 15 parts of titanium carbide, 3 - 5 parts of cobalt powder, 1 - 2 parts of chromium carbide, 1 - 2 parts of rare earth metal powder, and 2 - 8 parts of copper-zinc composite powder, and the rare earth metal powder includes 0.5 - 0.8 parts of 9AlC, 0.6 - 1 part of 5USCBN, 0.5 - 0.8 parts of yttrium, and 0.5 - 0.8 parts of cerium.

[0010] Furthermore, the purity of the titanium carbide powder is above 99%, and the purity of the cobalt powder is not less than 99%.

[0011] A production process of wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN, comprising the following steps: Step 1: Raw material selection and detection: Select high-purity raw materials and accurately detect the raw material components; Step 2: Put the raw materials and additives in Step 1 into a ball mill according to a certain ratio for mixing; Step 3: Put the mixed powder into a mold and use a forming method to make it preliminarily formed to obtain a blank; Step 4: Put the blank in Step 3 into a sintering furnace for sintering to obtain Product A; Step 5: Air cooling, add pig iron powder to a melting furnace for melting to obtain molten iron water, and desulfurize; Step 6: Add the Product A in Step 4 to the iron water in Step 5 for secondary melting alloying and rapid cooling to obtain an ingot product; Step 7: Perform surface treatment on the surface of the ingot product by PVD method and deposit a layer of TiN coating on the surface.

[0012] Furthermore, in Step 2, the particle size of the raw materials and additives after ball milling is between 2 - 5 microns.

[0013] Furthermore, in Step 2, the set time of the ball mill is 10 - 20 hours and the rotation speed is 100 - 300 revolutions per minute.

[0014] Furthermore, the forming methods in Step 3 are cold pressing and hot pressing. For cold pressing, the pressure is set between 100 - 500 MPa; for hot pressing, the temperature is set at 1000 - 1200 °C, the pressure is between 50 - 200 MPa, and the heat preservation and pressure holding time is 1 - 5 hours. The sintering steps in Step 4 are vacuum sintering and sintering in a protective gas atmosphere. In vacuum sintering, the vacuum degree needs to reach 10 -3 -10 -5 Pa; in sintering under an atmosphere protection, inert gases such as argon are used as the protective atmosphere, and the gas flow rate is 1 - 5 L / min.

[0015] Furthermore, in Step 6, the treatment temperature of the secondary melting is 800 - 900 °C, and the heat preservation time is 2 - 10 hours.

[0016] Beneficial effects

[0017] The technical solution provided by the present invention has the following beneficial effects compared with the known public technologies:

[0018] In the present invention, by setting TiC and USCBN as hard reinforcing phases and uniformly distributing them in the titanium matrix, the hardness and wear resistance of the alloy are significantly improved. The hardness of TiC can reach 3000HV, and the hardness of USCBN can reach 4000HV, enabling the alloy to withstand high-wear environments. By controlling the particle size and distribution of TiC and USCBN, the brittleness problem caused by the aggregation of hard phases is avoided, while the toughness of the alloy is maintained. Moreover, through two melting processes and the surface treatment method of PVD, the TiN coating can further improve the corrosion resistance and surface hardness of the alloy, and the alloy can be surface-treated.

[0019] In the present invention, the addition of cobalt and aluminum elements improves the high-temperature strength and oxidation resistance of the alloy. Cobalt can stabilize the high-temperature phase of the titanium matrix and delay the phase transformation at high temperatures, while aluminum forms a dense Al 2 O 3 oxide film on the surface, improving the oxidation resistance; and the alloy can still maintain high strength and hardness in the high-temperature environment of 600°C to 800°C, and is suitable for applications such as high-temperature engine components and gas turbine blades;

[0020] In the present invention, by optimizing the alloy composition, TiC-9ALC-5USCBN exhibits excellent corrosion resistance in strong acids (such as sulfuric acid, hydrochloric acid), strong alkalis (such as sodium hydroxide), and chlorine-containing media (such as seawater); the addition of cobalt elements improves the passivation ability of the alloy, while the uniformly distributed TiC and USCBN phases reduce the formation of corrosion micro-cells, further enhancing the corrosion resistance.

[0021] The alloy in the present invention not only has high hardness (≥500HV) and wear resistance, but also maintains good toughness (impact toughness ≥50J / cm 2 ) and fatigue resistance, and is suitable for high-stress alternating load environments; through hot isostatic cold pressing process, the density of the alloy is close to 100%, avoiding defects such as pores and inclusions, and further improving its mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 is the process flow chart for the preparation of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] The present invention will be further described below in conjunction with embodiments.

[0026] Embodiment 1: A wear-resistant, heat-resistant, and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN, as shown in the attached Figure 1 figures, includes: raw materials, including pig iron powder, titanium carbide, cobalt powder, chromium carbide, tungsten carbide, copper-zinc composite powder, and rare earth metal powder; additives, including 9ALC, 5USCBN, and yttrium and cerium rare earth elements; among the raw materials, by weight: 60 parts of pig iron powder, 20 parts of tungsten carbide, 10 parts of titanium carbide, 3 parts of cobalt powder, 1 part of chromium carbide, 1 part of rare earth metal powder, 2 parts of copper-zinc composite powder, and the rare earth metal powder includes 0.5 part of 9AlC, 0.6 part of 5USCBN, 0.5 part of yttrium, and 0.5 part of cerium.

[0027] The purity of the titanium carbide powder is above 99%, and the purity of the cobalt powder is not less than 99%. TiC and USCBN, as hard strengthening phases, are evenly distributed in the titanium matrix, significantly improving the hardness and wear resistance of the alloy. The hardness of TiC can reach 3000HV, and the hardness of USCBN can reach 4000HV, enabling the alloy to withstand a high-wear environment;

[0028] Embodiment 2: Among the raw materials, by weight: 80 parts of pig iron powder, 25 parts of tungsten carbide, 15 parts of titanium carbide, 5 parts of cobalt powder, 2 parts of chromium carbide, 2 parts of rare earth metal powder, 8 parts of copper-zinc composite powder, and the rare earth metal powder includes 0.8 part of 9AlC, 1 part of 5USCBN, 0.8 part of yttrium, and 0.8 part of cerium.

[0029] Embodiment 3: A production process of a wear-resistant, heat-resistant, and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN, including the following steps: Step 1: Raw material selection and detection: Select high-purity raw materials and accurately detect the raw material components; Step 2: Put the raw materials and additives in Step 1 into a ball mill for mixing in a certain proportion; Step 3: Put the mixed powder into a mold and cold press it into shape, with the pressure set between 100MPa to obtain a green body; Step 4: Put the green body in Step 3 into a sintering furnace for vacuum sintering, and the vacuum degree needs to reach 10 -3Pa; The product A is obtained. Step Five: Air cooling. Pig iron powder is added to a furnace for smelting to obtain molten iron. Desulfurization is carried out. Step Six: The product A obtained in Step Four is added to the molten iron in Step Five for secondary smelting alloying, and then rapidly cooled to obtain an ingot product. Step Seven: Surface treatment is carried out on the surface of the ingot product by PVD method, and a TiN coating is deposited on the surface.

[0030] In Step Two, the particle sizes of the raw materials and additives after ball milling are between 2 microns; by controlling the particle sizes and distributions of TiC and USCBN, the brittleness problem caused by hard phase aggregation is avoided, while the toughness of the alloy is maintained. And through the surface treatment methods of two smelting processes and PVD, the TiN coating can further improve the corrosion resistance and surface hardness of the alloy, and the surface of the alloy can be treated.

[0031] In Step Two, the set time of the ball mill is 10 hours and the rotation speed is 100 revolutions per minute.

[0032] In Step Six, the treatment temperature of the secondary smelting is 800 °C and the heat preservation time is 2 hours.

[0033] Example Four: A production process of wear-resistant, heat-resistant and corrosion-resistant titanium cobalt alloy TiC-9ALC-5USCBN, including the following steps: Step One: Raw material selection and detection: High-purity raw materials are selected and the raw material components are accurately detected; Step Two: The raw materials and additives in Step One are put into a ball mill for mixing according to a certain ratio. Step Three: The mixed powder is put into a mold and hot-pressed at a temperature set at 1200 °C and a pressure between 200 MPa for 5 hours to obtain a green body. The addition of cobalt and aluminum elements improves the high-temperature strength and oxidation resistance of the alloy. Cobalt can stabilize the high-temperature phase of the titanium matrix and delay the phase transformation at high temperatures, while aluminum forms a dense Al 2 O 3The oxide film improves the antioxidant ability; Step 4: Put the green body in Step 3 into a sintering furnace and sinter it in a protective gas atmosphere. When sintering under atmosphere protection, an inert gas such as argon is used as the protective atmosphere, and the gas flow rate is 1 - 5 L / min to obtain Product A. This alloy can still maintain high strength and hardness in a high-temperature environment of 600 °C to 800 °C and is suitable for applications such as high-temperature engine components and gas turbine blades; Step 5: Air-cool, add raw iron powder to a furnace for melting to obtain molten iron water, and desulfurize; Step 6: Add the Product A in Step 4 to the iron water in Step 5 for secondary melting alloying, and rapidly cool to obtain an ingot product; Step 7: Perform surface treatment on the surface of the ingot product by the PVD method, deposit a TiN coating on the surface. By optimizing the alloy composition, TiC-9ALC-5USCBN shows excellent corrosion resistance in strong acids (such as sulfuric acid, hydrochloric acid), strong alkalis (such as sodium hydroxide), and chlorine-containing media (such as seawater); The addition of cobalt element improves the passivation ability of the alloy, and the uniformly distributed TiC and USCBN phases reduce the formation of corrosion microcells, further enhancing the corrosion resistance.

[0034] In Step 2, the particle sizes of the raw materials and additives after ball milling are between 2 - 5 microns.

[0035] In Step 2, the set time of the ball mill is 20 hours and the rotation speed is 300 revolutions per minute.

[0036] In Step 6, the treatment temperature for secondary melting is 900 °C and the holding time is 10 hours; The alloy in the present invention not only has high hardness (≥500 HV) and wear resistance, but also maintains good toughness (impact toughness ≥50 J / cm 2 ) and anti-fatigue performance and is suitable for high-stress alternating load environments; Through hot isostatic cold pressing process, the density of the alloy is close to 100%, avoiding defects such as pores and inclusions, and further improving its mechanical properties.

[0037] 1. Performance test data:

[0038]

[0039]

[0040] Table 1 (Mechanical property test table)

[0041] Test item Test result Coefficient of thermal expansion (20 - 800 °C) <![CDATA[7.2×10 -6 / K]]> Thermal conductivity (W / m·K) 24.5±1.5 High temperature oxidation resistance (1000 °C, 100 h) Oxide layer thickness ≤ 5 μm

[0042] Table 2 (Performance test data)

[0043] Test condition <![CDATA[Wear rate (mm 3 / N·m)]]> Dry friction, load 50 N <![CDATA[1.2×10 -6 > Lubrication condition (engine oil) <![CDATA[0.4×10 -6 >

[0044] Table 3 (Thermal property test data)

[0045] Corrosion medium Corrosion rate (mm / year) 3.5% NaCl solution 0.008 <![CDATA[10% H 2 SO 4 solution]]> 0.15

[0046] Table 4 (Corrosion Resistance (ASTM G31 Standard))

[0047] 2. Microstructure Analysis

[0048] - XRD Pattern: The main phases are shown as TiC, Co phase and a small amount of Al 3 Ti and BN dispersed phases.

[0049] - SEM Image: It shows that the grain size is uniform (average grain diameter 2 - 3 μm), and the BN phase is uniformly distributed at the grain boundaries.

[0050] 3. Application Verification Examples

[0051] Cutting Tool Test:

[0052] - Workpiece Material: Nickel-based Superalloy (Inconel 718)

[0053] - Cutting Parameters:

[0054] - Cutting Speed: 120 m / min

[0055] - Feed Rate: 0.1 mm / rev

[0056] - Depth of Cut: 0.5 mm

[0057] - Results:

[0058] - Tool Life: 45 minutes (25 minutes for traditional TiC-Co tools)

[0059] - Surface Roughness (Ra): 0.8 μm (compared with 1.2 μm).

[0060] Experimental Conclusion: This example proves that the titanium cobalt alloy TiC-9ALC-5USCBN alloy optimizes the grain boundary bonding strength and self-lubricity by adding Al and BN. At the same time, the Co phase significantly improves the toughness. Its comprehensive performance is superior to traditional TiC-Co-based materials and is suitable for high-load cutting tools, aerospace high-temperature resistant components and other scenarios.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the present invention in each embodiment.

Claims

1. A wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN, characterized in that: Including; raw materials, including pig iron powder, titanium carbide, cobalt powder, chromium carbide, tungsten carbide, copper-zinc composite powder and rare earth metal powder, additives, including 9ALC, 5USCBN and yttrium, cerium rare earth elements.

2. The wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN according to claim 1 is characterized in that: The raw materials include, by weight: 60-80 parts of pig iron powder, 20-25 parts of tungsten carbide, 10-15 parts of titanium carbide, 3-5 parts of cobalt powder, 1-2 parts of chromium carbide, 1-2 parts of rare earth metal powder, and 2-8 parts of copper-zinc composite powder. The additives include, by weight: rare earth metal powder includes 0.5-0.8 parts of 9AlC, 0.6-1 parts of 5USCBN, 0.5-0.8 parts of yttrium and 0.5-0.8 parts of cerium.

3. The wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN according to claim 2 is characterized in that: The purity of titanium carbide powder is above 99%, and the purity of cobalt powder is not less than 99%.

4. A production process of wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN, characterized in that: The method comprises the following steps: Step 1: Raw material selection and testing: Select high-purity raw materials and accurately test the raw material composition; Step 2: Put the raw materials and additives in step 1 into a ball mill in a certain proportion and mix them. Step 3: Put the mixed powder into the mold and use the molding method to make it initially molded to obtain a green body. Step 4: Place the green body in step 3 into a sintering furnace for sintering to obtain product A. Step 5: Air cooling, adding pig iron powder into the furnace for smelting to obtain molten iron, desulfurization, Step 6: Add the product A of step 4 into the molten iron of step 5, perform secondary smelting and alloying, and rapidly cool to obtain a rough ingot product. Step 7: The surface of the rough ingot product is treated by a PVD method to deposit a layer of TiN coating on the surface.

5. The production process of the wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN according to claim 4 is characterized in that: In step 2, the particle size of the raw materials and additives after ball milling is between 2-5 microns.

6. The production process of the wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN according to claim 1 is characterized in that: In step 2, the ball mill is set for 10-20 hours and the rotation speed is 100-300 rpm.

7. The production process of the wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN according to claim 1 is characterized in that: The forming method in step 3 is cold pressing and hot pressing. For cold pressing, the pressure is set between 100-500MPa; for hot pressing, the temperature is set between 1000-1200℃, the pressure is between 50-200MPa, and the heat preservation time is 1-5 hours. The sintering step in step 4 is vacuum sintering and protective gas atmosphere sintering. During vacuum sintering, the vacuum degree needs to reach 10 -3 -10 -5 Pa; during atmosphere protection sintering, argon or other inert gases are used as the protective atmosphere, and the gas flow rate is 1-5L / min.

8. The production process of the wear-resistant, heat-resistant and corrosion-resistant titanium-cobalt alloy TiC-9ALC-5USCBN according to claim 1 is characterized in that: In step six, the treatment temperature of the secondary smelting is 800-900° C., and the holding time is 2-10 hours.

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