PROCESS FOR PREPARING MOLYBDENUM ALLOY BY ULTRA-HIGH-TEMPERATURE ROLLING

Abstract

Provided is a process for preparing a molybdenum alloy by ultra-high-temperature rolling. The molybdenum alloy is an ultra-high strength and toughness molybdenum alloy, and includes 95 wt % to 99.9 wt % of molybdenum and 0.1 wt % to 5 wt % of a nano-ceramic oxide particle. The process includes: (1) preparing an MOxSO.sub.3H aqueous solution; (2) preparing a precursor composite powder; (3) preparing a nano-ceramic oxide-reinforced molybdenum alloy powder by reduction; and (4) preparing the ultra-high strength and toughness molybdenum alloy by pressing and sintering.

Claims

1. A process for preparing a molybdenum alloy by ultra-high-temperature rolling, wherein the molybdenum alloy is an ultra-high strength and toughness molybdenum alloy, and comprises 95 wt % to 99.9 wt % of molybdenum and 0.1 wt % to 5 wt % of a nano-ceramic oxide particle.

2. The process according to claim 1, comprising the following steps: (1) preparing an MOxSO.sub.3H aqueous solution: mixing benzenesulfonic acid and a nano-ceramic oxide particle with a particle size of 10 nm to 200 nm in water to be uniform to obtain a mixed system, and subjecting the mixed system to hydrothermal reaction to obtain the MOxSO.sub.3H aqueous solution; (2) preparing a precursor composite powder: preparing a molybdenum salt aqueous solution with a concentration of 0.02 mol/L to 2.5 mol/L, adding the molybdenum salt aqueous solution into the MOxSO.sub.3H aqueous solution to obtain a mixed solution, adjusting the mixed solution to have a pH of 5.5 to 6.5 by adding lactic acid to obtain a solution system, and subjecting the solution system to stirring, drying, and pulverizing in sequence to obtain the precursor composite powder; (3) preparing a nano-ceramic oxide-reinforced molybdenum alloy powder by reduction: subjecting the precursor composite powder to two-stage reduction (i.e. first-stage reduction and second-stage reduction) in hydrogen to obtain the nano-ceramic oxide-reinforced molybdenum alloy powder, with a particle size of 0.5 m to 5 m; and (4) preparing the ultra-high strength and toughness molybdenum alloy by pressing and sintering: pressing the nano-ceramic oxide-reinforced molybdenum alloy powder, and then conducting sintering in a hydrogen atmosphere to obtain a nano-ceramic oxide-reinforced molybdenum alloy with a relative density of greater than 98%, and subjecting the nano-ceramic oxide-reinforced molybdenum alloy to ultra-high-temperature rolling to obtain the ultra-high strength and toughness molybdenum alloy.

3. The process according to claim 1, wherein the nano-ceramic oxide particle is one selected from the group consisting of zirconia, titania, alumina, hafnia, yttria, and lanthana.

4. The process according to claim 2, wherein in step (1) the hydrothermal reaction is conducted at a temperature of 60 C. to 90 C. for 2 h to 8 h under stirring at a speed of 50 r/min to 300 r/min.

5. The process according to claim 2, wherein in step (2) a molybdenum salt in the molybdenum salt aqueous solution is one or more selected from the group consisting of potassium molybdate, sodium molybdate, and ammonium molybdate.

6. The process according to claim 2, wherein in step (3) the first-stage reduction is conducted at a temperature of 350 C. to 550 C. for 4 h to 9 h with a hydrogen flow rate of 15 m.sup.3/h to 18 m.sup.3/h, and the second-stage reduction is conducted at a temperature of 800 C. to 950 C. for 8 h to 12 h with a hydrogen flow rate of 18 m.sup.3/h to 25 m.sup.3/h.

7. The process according to claim 2, wherein in step (4) the pressing is conducted in a cold isostatic press at a pressure of 150 MPa to 200 MPa for 15 min to 20 min.

8. The process according to claim 2, wherein in step (4) the sintering is conducted in a pressureless medium-frequency furnace at a temperature of 1,700 C. to 2,000 C. for 4 h to 10 h with a hydrogen flow rate of 18 m.sup.3/h to 25 m.sup.3/h.

9. The process according to claim 2, wherein in step (4) the ultra-high-temperature rolling is conducted at a cogging temperature of 1,500 C. to 1,700 C. by heating once in every one rolling pass with a single deformation of 30% to 50% and a total deformation of greater than 90%.

10. The process according to claim 1, wherein the ultra-high strength and toughness molybdenum alloy remains stable in a high-temperature environment of 1,500 C., has a tensile strength of not less than 600 MPa and an elongation of not less than 50% at room temperature, and has a tensile strength of not less than 230 MPa and an elongation of not less than 30% at a high temperature of 1,200 C.

11. The process according to claim 2, wherein the nano-ceramic oxide particle is one selected from the group consisting of zirconia, titania, alumina, hafnia, yttria, and lanthana.

12. The process according to claim 2, wherein the ultra-high strength and toughness molybdenum alloy remains stable in a high-temperature environment of 1,500 C., has a tensile strength of not less than 600 MPa and an elongation of not less than 50% at room temperature, and has a tensile strength of not less than 230 MPa and an elongation of not less than 30% at a high temperature of 1,200 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1A shows a morphology image of the ultra-high strength and toughness molybdenum alloy prepared in Example 1 of the present disclosure;

[0026] FIG. 1B shows a pole figure of the ultra-high strength and toughness molybdenum alloy prepared in Example 1 of the present disclosure;

[0027] FIG. 2A shows a morphology image of the ultra-high strength and toughness molybdenum alloy prepared in Example 2 of the present disclosure;

[0028] FIG. 2B shows a pole figure of the ultra-high strength and toughness molybdenum alloy prepared in Example 2 of the present disclosure;

[0029] FIG. 3A shows a morphology image of the ultra-high strength and toughness molybdenum alloy prepared in Example 3 of the present disclosure;

[0030] FIG. 3B shows a pole figure of the ultra-high strength and toughness molybdenum alloy prepared in Example 3 of the present disclosure;

[0031] FIG. 4A shows a morphology image of the pure molybdenum prepared in Comparative Example 1 of the present disclosure;

[0032] FIG. 4B shows a pole figure of the pure molybdenum prepared in Comparative Example 1 of the present disclosure;

[0033] FIG. 5A shows a morphology image of the ultra-high strength and toughness molybdenum alloy prepared in Comparative Example 2 of the present disclosure;

[0034] FIG. 5B shows a pole figure of the ultra-high strength and toughness molybdenum alloy prepared in Comparative Example 2 of the present disclosure; and

[0035] FIG. 6 shows engineering stress-strain curves at room temperature for the products prepared in Examples 1 to 3 and Comparative Examples 1 to 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] In order to better understand the content of the present disclosure, the present disclosure will be further explained below in conjunction with specific examples and drawings. The following examples provide detailed implementation methods and operating steps based on the technical solutions of the present disclosure, but the scope of the present disclosure is not limited to the following examples.

Example 1

[0037] (1) Benzenesulfonic acid and nano-zirconia ceramic particles with a particle size of 50 nm were mixed uniformly in water. A resulting mixture was subjected to hydrothermal reaction at 90 C. for 6 h to obtain a reactant, and the reactant was stirred to obtain an MOxSO.sub.3H aqueous solution.

[0038] (2) A molybdenum salt aqueous solution with a concentration of 1.0 mol/L was prepared with potassium molybdate, and then added into the MOxSO.sub.3H aqueous solution to obtain a mixed solution. The mixed solution was adjusted to have a pH of 6.0 by adding lactic acid, and then stirred, dried, and pulverized in sequence to obtain a precursor composite powder.

[0039] (3) The precursor composite powder was subjected to first-stage reduction at 550 C. for 8 h with a hydrogen flow rate of 17 m.sup.3/h and second-stage reduction at 925 C. for 10 h with a hydrogen flow rate of 22 m.sup.3/h, so as to obtain a nano-zirconia ceramic particle-reinforced molybdenum alloy powder with a particle size of 0.7 m.

[0040] (4) The nano-zirconia ceramic particle-reinforced molybdenum alloy powder was pressed in a cold isostatic press at 180 MPa for 20 min, and then sintered in a pressureless medium-frequency furnace at 1,960 C. for 6 h with a hydrogen flow rate of 20 m.sup.3/h in the furnace to obtain a nano-zirconia ceramic particle-reinforced molybdenum alloy with a relative density of 98.5%.

[0041] (5) The nano-zirconia ceramic particle-reinforced molybdenum alloy was subjected to ultra-high-temperature rolling at 1,550 C. for 7 rolling passes by heating once in every one rolling pass with a single deformation of 42% and a total deformation of 97.8%.

[0042] The ultra-high strength and toughness molybdenum alloy prepared by ultra-high-temperature rolling in Example 1 consists of: 99 wt % of molybdenum and 1 wt % of nano-zirconia ceramic particles, which has a tensile strength of 737 MPa and an elongation of 53%, and is 82.9% higher in tensile strength and 89.3% higher in elongation than traditional molybdenum alloys. The ultra-high strength and toughness molybdenum alloy shows high-temperature stability and has a texture strength of 2.98, as shown in FIG. 1A and FIG. 1B.

Example 2

[0043] (1) Benzenesulfonic acid and nano-alumina ceramic particles with a particle size of 20 nm were mixed uniformly in water. A resulting mixture was subjected to hydrothermal reaction at 70 C. for 8 h to obtain a reactant, and the reactant was stirred to obtain an MOxSO.sub.3H aqueous solution.

[0044] (2) A molybdenum salt aqueous solution with a concentration of 1.5 mol/L was prepared with sodium molybdate, and then added into the MOxSO.sub.3H aqueous solution to obtain a mixed solution. The mixed solution was adjusted to have a pH of 5.5 by adding lactic acid, and then stirred, dried, and pulverized in sequence to obtain a precursor composite powder.

[0045] (3) The precursor composite powder was subjected to first-stage reduction at 500 C. for 6 h with a hydrogen flow rate of 18 m.sup.3/h and second-stage reduction at 850 C. for 12 h with a hydrogen flow rate of 25 m.sup.3/h, so as to obtain a nano-alumina ceramic particle-reinforced molybdenum alloy powder with a particle size of 0.8 m.

[0046] (4) The nano-alumina ceramic particle-reinforced molybdenum alloy powder was pressed in a cold isostatic press at 200 MPa for 15 min, and then sintered in a pressureless medium-frequency furnace at 1,850 C. for 7 h with a hydrogen flow rate of 25 m.sup.3/h in the furnace to obtain a nano-alumina ceramic particle-reinforced molybdenum alloy with a relative density of 98.8%.

[0047] (5) The nano-alumina ceramic particle-reinforced molybdenum alloy was subjected to ultra-high-temperature rolling at 1,600 C. for 5 rolling passes by heating once in every one rolling pass with a single deformation of 47% and a total deformation of 95.82%.

[0048] The ultra-high strength and toughness molybdenum alloy prepared by ultra-high-temperature rolling in Example 2 consists of: 99.5 wt % of molybdenum and 0.5 wt % of nano-alumina ceramic particles, which has a tensile strength of 856 MPa and an elongation of 58.1%, and is 112.4% higher in tensile strength and 107.1% higher in elongation than traditional molybdenum alloys. The ultra-high strength and toughness molybdenum alloy shows high-temperature stability and has a texture strength of 2.82, as shown in FIG. 2A and FIG. 2B.

Example 3

[0049] (1) Benzenesulfonic acid and nano-titania ceramic particles with a particle size of 100 nm were mixed uniformly in water. A resulting mixture was subjected to hydrothermal reaction at 75 C. for 8 h to obtain a reactant, and the reactant was stirred to obtain an MOxSO.sub.3H aqueous solution.

[0050] (2) A molybdenum salt aqueous solution with a concentration of 2.5 mol/L was prepared with ammonium molybdate, and then added into the MOxSO.sub.3H aqueous solution to obtain a mixed solution. The mixed solution was adjusted to have a pH of 6.5 by adding lactic acid, and then stirred, dried, and pulverized in sequence to obtain a precursor composite powder.

[0051] (3) The precursor composite powder was subjected to first-stage reduction at 450 C. for 9 h with a hydrogen flow rate of 15 m.sup.3/h and second-stage reduction at 800 C. for 12 h with a hydrogen flow rate of 25 m.sup.3/h, so as to obtain a nano-titania ceramic particle-reinforced molybdenum alloy powder with a particle size of 0.5 m.

[0052] (4) The nano-titania ceramic particle-reinforced molybdenum alloy powder was pressed in a cold isostatic press at 190 MPa for 18 min, and then sintered in a pressureless medium-frequency furnace at 1,750 C. for 10 h with a hydrogen flow rate of 23 m.sup.3/h in the furnace to obtain a nano-titania ceramic particle-reinforced molybdenum alloy with a relative density of 98.9%.

[0053] (5) The nano-titania ceramic particle-reinforced molybdenum alloy was subjected to ultra-high-temperature rolling at 1,600 C. for 9 rolling passes by heating once in every one rolling pass with a single deformation of 35% and a total deformation 97.9%.

[0054] The ultra-high strength and toughness molybdenum alloy prepared by ultra-high-temperature rolling in Example 3 consists of: 98.5 wt % of molybdenum and 1.5 wt % of nano-titania ceramic particles, which has a tensile strength of 864 MPa and an elongation of 63%, and is 114.4% higher in tensile strength and 125% higher in elongation than traditional molybdenum alloys. The ultra-high strength and toughness molybdenum alloy shows high-temperature stability and has a texture strength of 2.31, as shown in FIG. 3A and FIG. 3B.

Comparative Example 1

[0055] (1) ammonium tetramolybdate was subjected to first-stage reduction at 550 C. for 8 h with a hydrogen flow rate of 18 m3-/h and second-stage reduction at 950 C. for 10 h with a hydrogen flow rate of 25 m3-/h, so as to obtain a molybdenum powder with a particle size of 3.5 m;

[0056] (2) the molybdenum powder was pressed in a cold isostatic press at 200 MPa for 20 min, and then sintered in a pressureless medium-frequency furnace at 1,960 C. for 10 h with a hydrogen flow rate of 20 m.sup.3/h in the furnace to obtain pure molybdenum with a relative density of 95.6%; and

[0057] (3) the pure molybdenum was subjected to ultra-high-temperature rolling at 1,100 C. for 9 rolling passes by heating once in every one rolling pass with a single deformation of 28% and a total deformation of 94.81%.

[0058] The pure molybdenum prepared in Comparative Example 1 has a tensile strength of 403 MPa, an elongation of 28%, and a texture strength of 11.79, as shown in FIG. 4A and FIG. 4B.

Comparative Example 2

[0059] (1) 100 nm nano-titania ceramic particles and ammonium tetramolybdate were mixed in a dual power mixer at a speed of 50 r/min for 6 h by solid-solid mixing to obtain a precursor composite powder;

[0060] (2) the precursor composite powder was subjected to first-stage reduction at 450 C. for 9 h with a hydrogen flow rate of 15 m.sup.3/h and second-stage reduction at 800 C. for 12 h with a hydrogen flow rate of 25 m.sup.3/h, so as to obtain a nano-titania ceramic particle-reinforced molybdenum alloy powder with a particle size of 1.5 m;

[0061] (3) the nano-titania ceramic particle-reinforced molybdenum alloy powder was pressed in a cold isostatic press at 190 MPa for 18 min, and then sintered in a pressureless medium-frequency furnace at 1750 C. for 10 h with a hydrogen flow rate of 23 m.sup.3/h in the furnace to obtain a nano-titania ceramic particle-reinforced molybdenum alloy with a relative density of 97.7%; and

[0062] (4) the nano-titania ceramic particle-reinforced molybdenum alloy was subjected to ultra-high-temperature rolling at 1,600 C. for 9 rolling passes by heating once in every one rolling pass with a single deformation of 35% and a total deformation 97.9%.

[0063] The ultra-high strength and toughness molybdenum alloy prepared by ultra-high-temperature rolling in Comparative Example 2 includes: 98.5 wt % of molybdenum and 1.5 wt % of nano-titania ceramic particles, which has a tensile strength of 700 MPa and an elongation of 26%, and is 73.7% higher in tensile strength and 7.1% lower in elongation than traditional molybdenum alloys. The ultra-high strength and toughness molybdenum alloy has a texture strength of 6.52, as shown in FIG. 5A and FIG. 5B.

[0064] In summary, referring to FIG. 6, it can be seen that the ultra-high strength and toughness molybdenum alloy prepared according to the present disclosure has superior overall properties, and exhibits a relatively high strength and a greatly improved toughness at room temperature.

[0065] The above are only preferred embodiments of the present disclosure, and the present disclosure may have other forms of embodiments based on the above preparation methods, which will not be listed one by one. Therefore, any simple modifications, equivalent changes and variations made to the above embodiments according to the technical concept of the present disclosure without departing from the contents of the technical solutions of the present disclosure shall fall in the scope of the technical solutions of the present disclosure.