A method for preparing a surface-porous Co2B compound

Abstract

This disclosure provides a method for preparing a surface-porous Co2B compound, characterized by comprising: providing Co powder and B4C powder; loading the Co powder and B4C powder into a ball mill jar and evacuating the vacuum; ball milling the Co powder and B4C powder in the ball mill jar to obtain a mixed powder; filling the mixed powder into a high-strength steel mold for pressing, controlling and holding the pressure to obtain a blank; placing the blank into a vacuum induction sintering furnace and evacuating the vacuum for vacuum sintering, introducing oxygen to decarburize at the highest temperature, and cooling to obtain a surface-porous Co2B compound. The surface-porous Co2B compound prepared by this invention can adsorb and aggregate boiler flue gas substances through its surface pores to resist dynamic flue gas erosion. Simultaneously, because the flue gas substances aggregate in the pores can be pinned, it is beneficial for the flue gas substances to exist stably on the surface of the Co2B compound, which can significantly improve the resistance to dynamic flue gas erosion.

Description

Technical Field

[0001] This invention relates to a method for preparing a surface-porous Co2B compound. Background Technology

[0002] For materials used in power plant boiler pipes and other applications subjected to long-term high-temperature flue gas corrosion, the "Stellit" alloy, widely used both domestically and internationally, offers excellent resistance to high-temperature damage, but its manufacturing cost is high. For many users and researchers dealing with high-temperature wear conditions, obtaining a material that is both cost-effective and performs well in service is a current expectation. Clearly, inventing a porous Co2B compound material capable of adsorbing boiler flue gas, thereby enhancing its resistance to dynamic flue gas corrosion by adsorbing and accumulating flue gas substances in its surface pores during service, and thus replacing "Stellit" alloy or dense cobalt-boron compound materials, has significant innovative value and engineering application potential. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a porous Co2B compound capable of adsorbing boiler flue gas.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A process for preparing a surface-porous Co2B compound, characterized by comprising the following steps:

[0006] The steps are as follows:

[0007] (1) Weigh Co powder and B4C powder with a purity of not less than 99% at a molar ratio of 8:1, load them into a ball mill jar and vacuum them;

[0008] (2) Place the ball mill jar into the ball mill and ball mill for 5 to 10 hours. Quickly fill the extracted Co and B4C mixed powder into the high-strength steel mold blank, control the pressure to 100 MPa to 500 MPa, and hold the pressure for 5 to 10 minutes.

[0009] (3) When the blank is placed in the vacuum induction sintering furnace, the vacuum is first drawn. When the maximum temperature reaches 950℃~1200℃, oxygen is introduced for 10min-30min to decarburize. The temperature is held for 10 hours to 30 hours. After sintering, the blank is cooled with the furnace to finally obtain a Co2B compound with controllable surface pore depth.

[0010] In the above process, the Co powder particle size is ≤50μm; the B4C powder particle size is ≤50μm.

[0011] The vacuum degree of the ball mill jar is <10. -1 Pa.

[0012] The vacuum degree of the vacuum sintering is <10.-1 Pa. The heating rate of the vacuum sintering is 1℃ / second to 5℃ / second.

[0013] The process for preparing porous Co2B compounds according to this invention is simple, and the production cost per kilogram is only 35% to 50% of that of Stellite alloy, thus significantly saving production costs. The surface pore depth of the prepared Co2B compound is controllable, and it has excellent resistance to high-temperature damage. For example, in a dynamic flue gas damage test (100 hours) conducted in a 700℃ high-temperature flue gas erosion simulation test chamber, under the same test conditions, its surface thickness loss is significantly lower than that of Stellite alloy compared to Stellite material, demonstrating a significantly higher cost-performance ratio. This makes it possible to replace the currently used, expensive Stellite alloy.

[0014] This invention can prepare Co2B compounds with controllable surface pore depth. The surface pores can adsorb and aggregate boiler flue gas substances to resist dynamic flue gas erosion. At the same time, the accumulation of flue gas substances in the pores can act as a pinning effect, which is conducive to the stable existence of flue gas substances on the surface of Co2B compounds, and can significantly improve the resistance to dynamic flue gas erosion. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart illustrating a method for preparing a surface-porous Co2B compound according to an embodiment of the present disclosure.

[0016] Figure 2 This is a photograph of the porous Co2B compound obtained in Example 1 of the present invention. Detailed Implementation

[0017] like Figure 1 As shown, an embodiment of the present invention provides a method for preparing a surface-porous Co2B compound, comprising:

[0018] Step S1: Provide Co powder and B4C powder;

[0019] Step S2: Load the Co powder and the B4C powder into a ball mill jar and evacuate the vacuum.

[0020] Step S3: The Co powder and the B4C powder are ball-milled using the ball mill jar to obtain a mixed powder;

[0021] Step S4: Fill the mixed powder into a high-strength steel mold to press the blank, control the pressure and maintain the pressure to obtain the blank;

[0022] Step S5: Place the blank into a vacuum induction sintering furnace and evacuate it for vacuum sintering. When the maximum temperature is reached, oxygen is introduced to decarburize it. After cooling, a porous Co2B compound is obtained.

[0023] Example 1:

[0024] (1) Co powder and B4C powder with a purity of 99.9% and a particle size of 50 μm were weighed at a molar ratio of 12:1 and then placed into a ball mill jar and evacuated. The vacuum degree of the ball mill jar was 10. -2 Pa;

[0025] (2) Place the ball mill jar into the ball mill and ball mill for 10 hours. Quickly fill the extracted Co and B4C mixed powder into the high-strength steel mold blank, control the pressure at 500MPa, and hold the pressure for 10 minutes.

[0026] (3) Place the billet into a vacuum induction sintering furnace, first evacuate the vacuum, and sinter at 1200℃ (the vacuum degree during sintering is 10). -2 Pa. The heating rate of the sintering furnace is 1℃ / second. Oxygen is introduced simultaneously for 30 minutes, and the temperature is held for 30 hours. After sintering, the furnace is cooled to obtain a Co2B compound with a surface pore depth of approximately 100μm to 300μm.

[0027] The porous Co2B sample obtained in this embodiment The surface hole depth is approximately 121 μm to 173 μm; for Stellite alloys Simultaneously, porous Co2B samples were placed in a high-temperature flue gas erosion simulation test chamber for dynamic flue gas damage testing at 700℃ for 100 hours. After the test, the samples were ultrasonically cleaned with acetone and then air-dried. The change in height after damage was measured using vernier calipers. The reduction in sample height before and after the test is shown in Table 1. The data in the table show that the alloy prepared in this invention exhibits significantly improved resistance to flue gas erosion, increasing by nearly double. Figure 1 The image shown is a photograph of the porous Co2B compound obtained in Example 1 of this invention.

[0028] Table 1

[0029]

[0030]

[0031] Example 2

[0032] The process in this embodiment is the same as in embodiment 1, except that some process parameters are different:

[0033] The Co powder had a purity of 99% and a particle size of 30 μm, while the B4C powder had a purity of 99.9% and a particle size of 50 μm. The ball milling time was 5 hours, and the purity of the milling jar was 10. -3 Pa; compaction pressure 100MPa, holding pressure for 10 minutes; during sintering, the heating rate of the vacuum furnace during the sintering process is 5℃ / second, first evacuated to 10℃.-3 Pa; oxygen is introduced for 10 minutes when the sintering temperature reaches 950℃, and the sintering holding time is 10 hours.

[0034] The obtained Co2B bulk sample with a porous surface (pore depth of approximately 52 μm to 72 μm) alloy with "Steryl" The comparison is shown in Table 2 (experimental conditions are the same as in Example 1).

[0035] Table 2

[0036] "Steryl" alloy <![CDATA[Surface porous Co2B]]> Height reduction (μm) 93.6 56.1

[0037] Example 3

[0038] The process in this embodiment is the same as in embodiment 1, except that some process parameters are different:

[0039] The Co powder had a purity of 99.9% and a particle size of 50 μm, while the B4C powder had a purity of 99% and a particle size of 20 μm. The ball milling time was 7 hours, and the purity of the milling jar was 10. -2 Pa; compaction pressure 300MPa, holding pressure for 7 minutes; during sintering, the heating rate of the vacuum furnace during the sintering process is 3℃ / second, first evacuated to 10℃. -3 Pa; when the sintering temperature reaches 1050℃, oxygen is introduced for 20 minutes, and the sintering holding time is 20 hours.

[0040] The obtained Co2B bulk samples with porous surfaces (pore depth approximately 83 μm to 106 μm) alloy with "Steryl" The comparisons are shown in Table 3 (experimental conditions are the same as in Example 1).

[0041] Table 3

[0042] "Steryl" alloy <![CDATA[Surface porous Co2B]]> Height reduction (μm) 93.6 47.3

[0043] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A method for preparing a surface-porous Co2B compound, characterized in that, The method includes: Co powder and B4C powder are available; The Co powder and B4C powder with a purity of not less than 99% were weighed at a molar ratio of 12:1 and then placed into a ball mill jar and vacuumed. The Co powder and the B4C powder were ball-milled using the ball mill jar to obtain a mixed powder. The mixed powder is filled into a high-strength steel mold to press a blank, and the pressure is controlled and maintained to obtain a blank. The blank is placed in a vacuum induction sintering furnace and vacuum sintered. When the maximum temperature of 950℃~1200℃ is reached, oxygen is introduced for 10min~30min to decarburize. After cooling, a porous Co2B compound is obtained.

2. The method according to claim 1, characterized in that, The vacuum degree of the ball mill jar is less than 10. -1 Pa.

3. The method according to claim 1, characterized in that, The process of ball milling the Co powder and the B4C powder using the ball mill jar includes: Place the ball mill jar into a ball mill and ball mill for 5 to 10 hours.

4. The method according to claim 1, characterized in that, The step of filling the mixed powder into a high-strength steel mold blank, controlling the pressure and maintaining the pressure includes: Control the pressure to 100MPa~500MPa; and / or, maintain the pressure for 5min~10min.

5. The method according to any one of claims 1 to 4, characterized in that, The particle size of the Co powder is no greater than 50 μm.

6. The method according to any one of claims 1 to 4, characterized in that, The particle size of the B4C powder is no greater than 50 μm.

7. The method according to any one of claims 1 to 4, characterized in that, The vacuum degree of the vacuum sintering is less than 10. - 1 Pa.

8. The method according to any one of claims 1 to 4, characterized in that, The heating rate of the vacuum sintering is 1℃ / second to 5℃ / second.

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