METAL MATERIAL AND IN-SITU EXSOLUTION MODIFICATION METHOD FOR A SURFACE THEREOF

Abstract

The invention discloses a method for in-situ exsolution modification of a surface of a metal material, which comprises steps of : (1) a substrate metal powder are fully mixed with a metal powder for modification to obtain a raw material powder; (2) the raw material powder obtained in step (1) are prepared into a metal material by a preparation method at a non-equilibrium condition; (3) a heat treatment on the metal material prepared in step (2) is performed so that the metal material reaches an equilibrium state; after cooling to room temperature, a doped phase is exsolved to the surface of the metal material to obtain a modified metal material.

Claims

1. A method for in-situ exsolution modification of a surface of a metal material, characterized in that the method comprises steps of: (1) mixing a substrate metal and a metal powder for modification to obtain a raw material powder; (2) preparing the raw material powder obtained in step (1) into a metal material by a preparation method at a non-equilibrium condition; (3) performing a heat treatment on the metal material prepared in step (2) so that the metal material reaches an equilibrium state; a doped phase is exsolved to the surface of the metal material to obtain a modified metal material.

2. The method according to claim 1, characterized in that in step (1), the substrate metal is at least one selected from the group consisting of Mn, Fe, Co, Ni, Cu, and Zn.

3. The method according to claim 1, characterized in that in step (1), the metal for modification is at least one selected from the group consisting of Mo, Ru, Rh, Pd, Ag, Ir, Pt, and Au.

4. The method according to claim 1, characterized in that in step (1), a metal for modification in the raw material powder has a mass percentage of 0.1%-15%.

5. The method according to claim 1, characterized in that in step (2), the preparation method at the non-equilibrium condition is at least one selected from the group consisting of supersonic flame spraying, explosion spraying, atmospheric plasma spraying, supersonic plasma spraying, (ultra) low pressure plasma spraying, plasma spray—physical vapor deposition, electron beam deposition, cold spraying and laser 3D printing.

6. The method according to claim 1, characterized in that in step (3), the heat treatment has a temperature of 500° C.-900° C., duration of the heat treatment is 1 hour-24 hours.

7. The method according to claim 1, characterized in that in step (1), the mixing is mechanical mixing or spray granulation.

8. The method according to claim 1, characterized in that in step (3), the heat treatment is under vacuum, in a protective atmosphere, or in a reducing atmosphere.

9. A metal material prepared by the method according to any claim 1.

10. The metal material according to claim 9, characterized in that a doped metal is pinned on the surface of the substrate metal; the doped metal has a nanostructure.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1 is an SEM image of a surface of an untreated coated catalyst obtained in embodiment 1 according to the present invention;

[0024] FIG. 2 is an SEM image of the surface of the coated catalyst after 4 hours of heat treatment according to embodiment 1 of the present invention.

[0025] FIG. 3 is an SEM image of the surface of the coated catalyst after 8 hours of heat treatment according to embodiment 1 of the present invention.

[0026] FIG. 4 is an EDX analysis result of the surface of the untreated coated catalyst obtained in embodiment 1 according to the present invention.

[0027] FIG. 5 is an EDX analysis result of the surface of the coated catalyst after 8 hours of heat treatment according to embodiment 1 of the present invention.

[0028] FIG. 6 is an SEM image of a surface of an untreated coated catalyst obtained in embodiment 2 according to the present invention.

[0029] FIG. 7 is an SEM image of the surface of the coated catalyst after 4 hours of heat treatment according to embodiment 2 of the present invention.

[0030] FIG. 8 is an SEM image of the surface of the coated catalyst after 8 hours of heat treatment according to embodiment 2 of the present invention.

[0031] FIG. 9 is an EDX result of a cross-sectional surface layer of the coated catalyst after 8 hours of heat treatment according to embodiment 2 of the present invention;

[0032] FIG. 10 is an EDX result of the cross-section of a bulk phase of the coated catalyst after 8 hours of heat treatment according to embodiment 2 of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

[0033] In order to better illustrate the objective, technical solutions and advantages of the present invention, the present invention will be further described with reference to the drawings and embodiments.

Embodiment 1

[0034] As an embodiment of the metal material of the present invention, the metal material of this embodiment was prepared by the following method:

[0035] 287.5 g Ni metal powder was weighed as a substrate metal powder, and 25 g Ag metal powder was weighed as a modification metal powder. The mass percentage of the modification metal powder was 8%. The powders weighed were transferred into a V-shaped mixer and mixed for 24 hours at a rotating speed of 10 r min.sup.−1. The fully mixed material will be used at a later stage as a raw material powder. A coated catalyst was prepared from the aforementioned raw material powder by an atmospheric plasma spraying equipment (APS). Under the protection of 20 ml min.sup.−1 of hydrogen, two batches of the coated catalyst prepared were heated to 800° C. and kept at this temperature for 4 hours and 8 hours respectively. After sintering was completed, a quartz tube was opened and samples were taken out; these samples are the metal materials modified by in-situ exsolution.

[0036] SEM tests were performed on surfaces of the original coated catalyst without heat treatment, the coated catalyst after the 4 h heat treatment and the coated catalyst after the 8 h heat treatment respectively. As shown in FIGS. 1-3, there were many undissolved powdered particles on the surface of the untreated coated catalyst. After the 4 h heat treatment, the undissolved particles on the surface visibly decreased, the surface became smooth and grain boundaries began to emerge. At the same time, a small number of exsolved small particles appeared at some grain boundaries. After the 8 h heat treatment for 8 hours, the undissolved irregular particles had completely disappeared, and a large number of spherical nano-Ag particles were pinned at the grain boundaries of Ni. EDX analysis was performed on SEM-selected surface areas of the untreated catalyst and the catalyst after the 8 h heat treatment. As shown in FIGS. 4-5, the amount of Ag on the surface increased significantly after heat treatment, that is, the exsolved nanoparticles in FIG. 3 are Ag particles used for modification. The aforementioned results indicate that a modified catalyst having an in-situ exsolved nano-pinning structure can be obtained by an in-situ exsolution modification method.

Embodiment 2

[0037] As an embodiment of a metal material of the present invention, the metal material of this embodiment was prepared by the following method:

[0038] 475 g Ni metal powder was weighed as substrate metal powders and 25 g Ag metal powder was weighed as a modification metal powder, and the mass percentage of the modification metal powder was 5%. The powders weighed were transferred into a ball milling tank and mixed with water, which acts as a dispersant, for 6 hours at a rotating speed of 400 r min.sup.−1 to allow thorough mixing. The mixture was then dried in an oven to produce a raw material powder for later use. A coated catalyst was prepared from the aforementioned raw material powders through adopting a cold spraying (CS) equipment. The coated catalyst prepared was sealed in a quartz tube, the quartz tube was vacuumized at room temperature and then refilled with 300 mbar argon. The sealed quartz tube was heated to 800° C. in a muffle furnace, followed by kept at this temperature for 4 hours and 8 hours respectively. After sintering was completed, the quartz tube was opened and samples were taken out; these samples are the metal materials modified by in-situ exsolution.

[0039] During the preparation process, SEM tests were performed on the surfaces of the original coated catalyst without heat treatment, the coated catalyst after the 4 h heat treatment and the coated catalyst after 8 h heat treatment respectively. As shown in FIGS. 6-8, there were many undissolved powder particles on the surface of the untreated coated catalyst. After the 4 h heat treatment, the undissolved particles on the surface visibly decreased, the surface became smooth and the grain boundaries began to emerge. At the same time, a small number of small particles appeared at some grain boundaries. After the 8 h heat treatment, the undissolved irregular particles had completely disappeared, and a large number of spherical nano-Ag particles were pinned at the grain boundaries of Ni. EDX tests were performed on a cross-sectional surface layer and a cross-sectional bulk phase of the coated catalyst after the 8 h heat treatment (FIGS. 9-10). It can be seen that the amount of Ag on the surface layer increased significantly after heat treatment, that is, Ag in the coated bulk phase tended to diffuse toward the surface. The aforementioned results indicate that a modified catalyst having an in-situ exsolved nano-pinning structure can be obtained by an in-situ exsolution modification method.

Embodiment 3

[0040] As an embodiment of a metal material of the present invention, the metal material of this embodiment was prepared by the following method:

[0041] 499.5 g Fe metal powder was weighed as substrate metal powder and 0.5 g Au metal powder was weighed as modification metal powder, the percentage mass of modification metal powder was 0.1 mass %; the powder weighed was transferred into a ball milling tank and mixed with water, which acts as a dispersant, for 6 hours at a rotating speed of 400 r min.sup.−1 to allow thorough mixing. The mixture was then dried in an oven to produce a raw material powder for later use. A coated catalyst was prepared from the aforementioned raw material powders through adopting an atmospheric plasma spraying. The coated catalyst prepared was sealed in a quartz tube, the quartz tube was vacuumized at room temperature and then refilled with 300 mbar argon. The sealed quartz tube was heated to 500° C. in a muffle furnace, followed by kept at this temperature for 8 hours and 12 hours respectively. After sintering was completed, the quartz tube was opened and samples were taken out; these samples are the metal materials modified by in-situ exsolution.

[0042] The analysis of the surface morphology of the metal materials modified by in-situ exsolution prepared was the same as that of embodiment 1 and embodiment 2, and will not be repeated here.

Embodiment 4

[0043] According to an embodiment of a metal material of the present invention, the metal material in this embodiment was prepared by the following method:

[0044] 425 g Co metal powder was weighed as substrate metal powder and 75 g Pt metal powder was weighed as modification metal powder, the percentage mass of modification metal powder was 15%; the powder weighed was transferred into a ball milling tank and mixed with water, which acts as a dispersant, for 6 hours at a rotating speed of 400 r min.sup.−1 to allow thorough mixing. The mixture was then dried in an oven to produce a raw material powder for later use. A coated catalyst was prepared from the aforementioned raw material powders by electron beam deposition; the coated catalyst prepared was sealed in a quartz tube, the quartz tube was vacuumized at room temperature and then refilled 300 mbar argon. The sealed quartz tube was heated to 900° C. in a muffle furnace, followed by kept at this temperature for 4 hours and 8 hours respectively. After sintering was completed, the quartz tube was opened and samples were taken out; these samples are the metal materials modified by in-situ exsolution.

[0045] The analysis of the surface morphology of the metal materials modified by in-situ exsolution prepared was the same as that of embodiment 1 and embodiment 2, and will not be repeated here.

[0046] It should be finally noted that the aforementioned embodiments merely illustrate the technical solutions of the present invention. They are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.