An alloy for high temperature molten metal catalyst corrosion resistance and its forming method

Abstract

This invention proposes an alloy resistant to corrosion by high-temperature molten metal catalysts and its forming method. The alloy comprises, by weight percentage: W: 0.01-0.2 wt.%; Si: 0.6-4.4 wt.%; Ti: 0.001-0.1 wt.%; B: 0.005-1.5 wt.%; Cr: 0.002-1.6 wt.%; Cu: 0.001-0.1 wt.%; N: 0.001-0.15 wt.%; O: <0.01 wt.%; S: <0.01 wt.%; P <0.01 wt.%. The alloy material of this invention exhibits excellent resistance to high-temperature corrosion by Bi-containing molten metal catalysts and possesses high-temperature strength. This material can be used as a material for reactors, burners, and high-temperature, high-pressure pipelines in methane cracking hydrogen production units that use high-temperature liquid molten metal catalysts, thereby solving the bottleneck problem of current alloy materials being susceptible to corrosion by high-temperature (>850℃) molten metals.

Description

Specification 1 Alloy Resistant to Corrosion by High-Temperature Molten Metal Catalysts and Its Forming Method Technical Field This invention belongs to the field of hydrogen production technology, and particularly relates to an alloy resistant to corrosion by high-temperature molten metal catalysts and its forming method. Background Art The current energy structure is shifting towards low-carbon, clean, and efficient production. Hydrogen energy, due to its high energy density, carbon-free combustion products, and diverse and sustainable sources, is considered an important part of building clean energy. Currently, the main methods for producing hydrogen energy include water electrolysis, petrochemical hydrogen production, industrial by-product purification, and bio-hydrogen production. Although water electrolysis has advantages such as simple equipment and high purity, its process has high energy consumption, and currently, water electrolysis is generally produced using renewable energy sources such as solar and wind power. The limitations of renewable energy hydrogen production technology due to cost, energy consumption, resource distribution, and seasonality are major obstacles to the large-scale industrial application of water electrolysis. Industrial by-product hydrogen production refers to by-products generated during product manufacturing. These by-products typically have low purity and many impurities, requiring multiple purification processes to obtain high-purity hydrogen. Therefore, fossil fuel-based hydrogen production will dominate. Methane, due to its high hydrogen-to-carbon ratio, is considered a relatively ideal raw material for hydrogen production. In methane-based hydrogen production technologies, steam reforming (SMR) and thermal cracking (TDM) are the main technical routes. Compared to SMR, thermal cracking has the following significant advantages: 1. Only hydrogen and solid carbon are produced, with no direct COx emissions, avoiding a complex carbon capture process; 2. The energy consumption per unit volume of hydrogen produced by thermal cracking is only half that of steam reforming and equivalent to 15% of water electrolysis; the energy saving effect is very significant; 3. The equipment required for the thermal cracking reaction is compact, the process flow is less complex, and a high-pressure reaction system is not required; 4. The direct byproduct of cracking is high-value-added graphite carbon, which can significantly improve the economic benefits and competitiveness of this technology. However, currently, methane thermal cracking hydrogen production technology encounters the following bottleneck: the methane thermal cracking process requires the use of a metal catalyst for reaction activation. Since solid metal catalysts are easily deactivated, liquid metal catalysts (especially Bi-containing liquid metals) are preferred for reaction activation. Generally, the core temperature of liquid metal catalytic reactors exceeds 850℃ (higher than the service temperature of liquid metals used in the nuclear energy field). At this temperature, Bi-containing molten metal catalysts cause severe corrosion (LMC) to reaction vessels and accessories made of various metals, including but not limited to high-temperature alloys (Ni-based, NiCr-based, CoNi-based), high-temperature steel (FeCrNi-based), heat-resistant alloys (FeCr-based), and other metal materials. At the same time, high-temperature hydrogen also degrades the reactor and pipe walls, leading to a decrease in high-temperature mechanical properties (HTHA), which greatly limits the industrial application of this method.The present invention aims to provide an alloy resistant to corrosion by high-temperature molten metal catalysts and its forming method. This alloy can resist corrosion by Bi-containing molten metal catalysts under high-temperature conditions (>850℃); simultaneously, the alloy can effectively resist high-temperature hydrogen erosion (possessing high-temperature resistance) and has excellent high-temperature mechanical properties. The technical solution adopted is as follows: An alloy resistant to corrosion by high-temperature molten metal catalysts, comprising the following alloy components by weight percentage: W: 0.01-0.2wt.%; Si: 0.6-4.4wt.%; Ti: 0.001-0.1wt.%; B: 0.005-1.5wt.%; Cr: 0.002-1.6wt.%; Cu: 0.001-0.1wt.%; N: 0.001-0.15wt.%; O: <0.01wt.%; S: <0.01wt.%; P <0.01wt.%; balance Mo. Preferably, it comprises the following alloy composition: W: 0.01-0.15 wt.%; Si: 0.7-4.1 wt.%; Ti: 0.001-0.1 wt.%; B: 0.07-1.5 wt.%; Cr: 0.005-1.5 wt.%; Cu: 0.005-0.1 wt.%; N: 0.01-0.10 wt.%; O: <0.003 wt.%; S: <0.003 wt.%; P <0.003 wt.%; balance Mo. The high-temperature molten metal catalyst in this invention refers to a molten metal catalyst containing bismuth (Bi). The alloy resistant to corrosion of the high-temperature molten metal catalyst is a molybdenum (Mo) alloy. In this invention, the addition of alloying element W can melt into the base metal and react with other alloying elements to form a strengthening phase, improving high-temperature yield strength and tensile strength. O, S, and P reduce the corrosion resistance of the alloy in Bi-containing molten metal, and their content must be strictly controlled. N can form nano-Mo2N with Mo, which can effectively improve the high-temperature strength and creep life of Mo alloys, but its content must be strictly controlled to prevent it from transforming into harmful δ-structure and coarsening of precipitates, leading to a decrease in the high-temperature performance of the alloy. A method for forming an alloy resistant to high-temperature molten metal catalyst corrosion includes the following steps: Step 1: Classify and sieve the spherical powder corresponding to the alloy composition to obtain alloy powder with a particle size range of 1um-50um, and mix the powder. Before Step 1, the method further includes: preparing alloy powder from the alloy raw materials used for forming, wherein the alloy powder is spherical powder with a sphericity > 0.8. Step 2: Press the above alloy powder to form an alloy billet. Step 3: Sinter the above alloy billet in a protective atmosphere. Preferably, in step 2, the pressure range is 50-600 MPa; the temperature range is 3-40°C.Preferably, in step 3, the sintering temperature is 1500℃-2300℃; the protective atmosphere is hydrogen, and the gas purity is ≥99.9%. Preferably, in step 3, the sintered component is used to load the Bi-containing molten metal catalyst, and it can be any one of a container, pipe, or reactor. HK 20105434 B Specification 4 Compared with the prior art, the advantages of the present invention are: by strictly selecting the types and contents of alloying elements, the above alloying elements possess special interactions, resulting in the alloy having the ability to resist corrosion of Bi-containing liquid molten metal catalysts and possess excellent high-temperature strength at 1000℃ and above. Specifically: 1. Adding alloying elements Cr, Si, B, Ti, and W can significantly improve the alloy's resistance to corrosion of Bi-containing molten metal. The aforementioned alloying elements, designed by weight percentage, will form the (Mox1,Cry1)5Si3 phase, (Mox2,Cry2)5SiB2 phase, (Mox3,Cry3)3Si phase, and (Mo,Ti,W)ss phase, respectively. The (Mox1,Cry1)5Si3, (Mox2,Cry2)5SiB2, and (Mox3,Cry3)3Si phases all possess excellent resistance to high-temperature corrosion from Bi (bismuth)-containing molten metals, high-temperature oxidation resistance, and high-temperature creep resistance. The (Mo,Ti,W)ss phase provides the alloy with excellent toughness at high temperatures and significantly reduces the ductile-brittle transition temperature (DBTT) of the Mo alloy. 2. The addition of the alloying element Cu can be incorporated into the above four complex phases, further improving the alloy's resistance to corrosion from Bi-containing molten metals. 3. The Mo alloy exhibits good high-temperature yield strength, tensile strength, and corrosion resistance. Figure 1 is a comparison of the corrosion rates of Example 1 and the comparative example in molten metal catalyst; Figure 2 is a comparison of the corrosion rates of Example 2 and the comparative example in molten metal catalyst; Figure 3 is a comparison of the corrosion rates of Example 3 and the comparative example in molten metal catalyst. Detailed Description: The alloy resistant to high-temperature molten metal catalyst corrosion and its forming method of the present invention will be described in more detail below with reference to the schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving the advantageous effects of the invention.This invention proposes an alloy resistant to corrosion by high-temperature molten metal catalysts, comprising the following alloy components by weight percentage: W: 0.01-0.2 wt.%; Si: 0.6-4.4 wt.%; Ti: 0.001-0.1 wt.%; B: 0.005-1.5 wt.%; Cr: 0.002-1.6 wt.%; Cu: 0.001-0.1 wt.%; N: 0.001-0.15 wt.%; O: <0.01 wt.%; S: <0.01 wt.%; P <0.01 wt.%; balance Mo. Further, the alloy resistant to corrosion by high-temperature molten metal catalysts comprises the following alloy composition: W: 0.01-0.15 wt.%; Si: 0.7-4.1 wt.%; Ti: 0.001-0.1 wt.%; B: 0.07-1.5 wt.%; Cr: 0.005-1.5 wt.%; Cu: 0.005-0.1 wt.%; N: 0.01-0.10 wt.%; O: <0.003 wt.%; S: <0.003 wt.%; P <0.003 wt.%; the balance is Mo. This invention also proposes a method for forming an alloy resistant to corrosion by high-temperature molten metal catalysts, comprising the following steps: Step 1: Classifying and sieving the spherical powder corresponding to the alloy composition to obtain alloy powder with a particle size range of 1 μm-50 μm, and mixing the powder; Step 2: Pressing the above alloy powder to form an alloy billet. The pressure range is 50-600 MPa; the temperature range is 3-40℃. Step 3: Sinter the above alloy billet in a protective atmosphere. The sintering temperature is 1500℃-2300℃; the protective atmosphere is hydrogen. The sintered component is used to load a Bi-containing molten metal catalyst, which can be any of the following: container, pipe, or reactor. Example 1 HK 20105434 B Specification 6 This example provides an alloy resistant to high-temperature molten metal catalyst corrosion, its forming, and a comparative test on high-temperature molten metal catalyst corrosion resistance. The comparative metal alloy is a superalloy resistant to high-temperature oxidation and corrosion. The superalloys are INCONEL@ 617, HAYNES@ HR-230, and HAYNES@ HR-235. Sample preparation: Alloy powder was prepared according to the nominal composition as follows: W: 0.1 wt.%; Si: 1.9 wt.%; Ti: 0.1 wt.%; B: 0.9 wt.%; Cr: 0.01 wt.%; Cu: 0.009 wt.%; N: 0.06 wt.%; O: <0.002 wt.%; S: <0.002 wt.%; P <0.002 wt.%; with the balance being Mo.The comparative metal alloy compositions are shown in Table 1: Table 1 Nominal composition (wt%) of comparative alloys Comparative alloy Cr W Mo Co AL Cu Si Mn Fe BC Ni Ti INCONEL@ 617 22 / 9 12.5 1 < 0.5 < 1.0 < 1.0 < 3 < 0.006 0.07 54 < 0.6 HAYNES@ HR-230 22 14 2 < 5 / / 0.4 0.5 < 5 < 0.015 0.10 57 / HAYNES@ HR-235 31 / 5.6 3.8 < 0.4 3.8 < 0.6 < 0.7 < 1.5 / 0.06 58 / Step 1: The alloy powder is graded and sieved to obtain a particle size range of 1um-50um. The alloy powder was mixed with other materials. Step 2: The alloy powder was pressed into a compact at a temperature of 12℃ and a pressure of 220MPa. Step 3: The alloy compact was sintered in a protective atmosphere at a sintering temperature of 1950℃. The alloy microstructure was (Mo,Cr)5Si3, (Mo,Cr)5SiB2, (Mo,Cr)3Si, and (Mo,Ti,W)ss. Step 4: The compact was subjected to a high-temperature corrosion test in a molten metal catalyst according to ASTM G1-03 standard at a test temperature of 1000℃ for 72 hours. HK 20105434 B Specification 7 In this embodiment and other embodiments, the specific operation of the high-temperature corrosion test is as follows: molten metal catalyst containing bismuth (Bi) is placed into the sintered component. Step 5: The comparative metal parts were subjected to a high-temperature corrosion test in the same environment according to ASTM G1-03 for 72 hours. The experimental comparison results are shown in Table 2 and Figure 1. Table 2 Corrosion Rate and Resistance to Molten Metal in Example 1 and Comparative Examples (3 Comparative Metal Alloys) Example 1 INCONEL@ 617 HAYNES@ HR-230 HAYNES@ HR-235 Corrosion Rate (mm / year) 3.0 24.0 27.9 42.9 Example 2 This example provides an alloy resistant to high-temperature molten metal catalyst corrosion, its forming process, and comparative tests on its resistance to high-temperature molten metal catalyst corrosion. The comparative metals are high-temperature corrosion resistant oxidation superalloys, namely INCONEL@ 617, HAYNES@ HR-230, and HAYNES@ HR-235.Sample preparation: Alloy powder was prepared according to the nominal composition: W: 0.1 wt.%; Si: 2.4 wt.%; Ti: 0.07 wt.%; B: 0.8 wt.%; Cr: 1.1 wt.%; Cu: 0.01 wt.%; N: 0.04 wt.%; O: <0.002 wt.%; S: <0.002 wt.%; P <0.002 wt.%; with the balance being Mo. The nominal composition of the comparative alloy is shown in Table 1. Step 1: The alloy powder raw material was graded and sieved to obtain alloy powder with a particle size range of 1 μm-47 μm, and then mixed. Step 2: The above alloy powder was pressed into a compact at a temperature of 15 °C and a pressure of 250 MPa. Step 3: The above alloy compact was sintered in a protective atmosphere at a sintering temperature of 2050 °C. The alloy microstructure was the same as in Example 1. Step 4: The molded parts were subjected to a high-temperature corrosion test in a molten metal catalyst according to ASTM G1-03 standard. The test temperature was 1000℃, and the test time was 72 hours. Step 5: The comparison metal parts were also subjected to a high-temperature corrosion test in the same environment according to ASTM G1-03. The test temperature was 1000℃, and the test time was 72 hours. The experimental comparison results are shown in Table 3 and Figure 2. Table 3 Corrosion Rate in Molten Metal and Resistance to Corrosion of Example 2 and Comparative Example Example 2 INCONEL@ 617 HAYNES@ HR-230 HAYNES@ HR-235 Corrosion Rate (mm / year) 2.8 20.6 27.5 40.3 Example 3 This example provides an alloy resistant to corrosion by a high-temperature molten metal catalyst, its forming, and a comparative test on its resistance to corrosion by a high-temperature molten metal catalyst. The comparative metals are high-temperature oxidation corrosion resistant superalloys, namely INCONEL@ 617, HAYNES@ HR-230, and HAYNES@ HR-235; the nominal composition of the comparative alloys is shown in Table 1. Sample preparation: Alloy powder was prepared according to the nominal composition as follows: W: 0.071 wt.%; Si: 1.9 wt.%; Ti: 0.011 wt.%; B: 1.0 wt.%; Cr: 0.82 wt.%; Cu: 0.02 wt.%; N: 0.08 wt.%; O: <0.002 wt.%; S: <0.002 wt.%; P <0.002 wt.%; with the balance being Mo.Step 1: The alloy powder raw material is graded and sieved to obtain alloy powder with a particle size range of 1um-45um, and then mixed. Step 2: The above alloy powder is pressed into a compact at a temperature of 19℃ and a pressure of 200MPa. Step 3: The above alloy compact is sintered in a protective atmosphere at a sintering temperature of 22009℃. The alloy microstructure is the same as in Example 1. Step 4: The molded part is subjected to a high-temperature corrosion test in a molten metal catalyst according to ASTM G1-03 standard at a test temperature of 1050℃ for 72 hours. Step 5: The comparison metal part is also subjected to a high-temperature corrosion test in the same environment according to ASTM G1-03 at a test temperature of 1050℃ for 72 hours. The experimental comparison results are shown in Table 4 and Figure 3. Table 4 Corrosion Rate and Resistance to Molten Metal in Example 3 and Comparative Example 3 INCONEL@ 617 HAYNES@ HR-230 HAYNES@ HR-235 Corrosion Rate (mm / year) 4.5 30.1 37.4 56.7 The results confirm that, compared with the comparative example, the example exhibits superior resistance to molten metal corrosion at 1000℃ and 1050℃. Furthermore, the corrosion rate of alloy components containing O, S, and P, which are outside the scope of this patent, increased significantly in the same environment as in Example 3, indicating that these harmful elements can reduce the resistance to corrosion by Bi-containing molten metal. The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention are considered as not departing from the scope of the present invention and are still within the protection scope of the present invention. HK 20105434 B Claim 1 1. An alloy resistant to corrosion by high-temperature molten metal catalysts, characterized in that, by weight percentage, it comprises the following alloy components: W: 0.01-0.2 wt.%; Si: 0.6-4.4 wt.%; Ti: 0.001-0.1 wt.%; B: 0.005-1.5 wt.%; Cr: 0.002-1.6 wt.%; Cu: 0.001-0.1 wt.%; N: 0.001-0.15 wt.%; O: <0.01 wt.%; S: <0.01 wt.%; P <0.01 wt.%; the balance being Mo.2. The alloy resistant to corrosion by high-temperature molten metal catalysts according to claim 1, characterized in that it comprises the following alloy composition: W: 0.01-0.15 wt.%; Si: 0.7-4.1 wt.%; Ti: 0.001-0.1 wt.%; B: 0.07-1.5 wt.%; Cr: 0.005-1.5 wt.%; Cu: 0.005-0.1 wt.%; N: 0.01-0.10 wt.%; O: <0.003 wt.%; S: <0.003 wt.%; P <0.003 wt.%; balance Mo. 3. A method for forming an alloy resistant to corrosion by a high-temperature molten metal catalyst, used to prepare the alloy resistant to corrosion by a high-temperature molten metal catalyst as described in any one of claims 1-2, characterized by comprising the following steps: Step 1, classifying and sieving spherical powders corresponding to the alloy composition to obtain alloy powders with a particle size range of 1µm-50µm, and mixing the powders; Step 2, pressing the above alloy powders into a compact to form an alloy billet; Step 3, sintering the above alloy billet in a protective atmosphere. 4. The method for forming an alloy resistant to corrosion by a high-temperature molten metal catalyst according to claim 3, characterized in that, in step 2, the pressure range is 50-600 MPa; the temperature range is 3-40℃. 5. The method for forming an alloy resistant to corrosion by a high-temperature molten metal catalyst according to claim 3, characterized in that, in step 3, the sintering temperature is 1500℃-2300℃; the protective atmosphere is hydrogen. 6. The alloy forming method for resisting corrosion by high-temperature molten metal catalyst according to claim 3, characterized in that, in step 3, the sintered component is used to load the Bi-containing molten metal catalyst, and it is any one of a container, pipe, and reactor. HK 20105434 B Specification Figure 1 Figure 2 HK 20105434 B Specification Figure 2 Figure 3 HK 20105434 B.

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