A method for producing a molybdenum material

Abstract

The application relates to a preparation method of molybdenum material, in particular to the field of target material, and the preparation method comprises the following steps: cold pressing molybdenum powder to obtain a blank; and sintering the blank to obtain molybdenum material; the particle size of the molybdenum powder comprises the following: 1-10 mu m molybdenum powder, 15-25 mu m molybdenum powder and 60-70 mu m molybdenum powder; and the sintering is assisted by ultrasonic waves. The preparation method provided by the application realizes the preparation of molybdenum material with basically no porosity defects and small grains by adopting powder grading and ultrasonic waves in sintering, and the molybdenum material still has good use effect, and the utilization rate of the molybdenum material is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of target materials, and more specifically to a method for preparing molybdenum material. Background Technology

[0002] Molybdenum metal sputtered thin films have broad market prospects in fields such as solar cells, flat panel displays, and semiconductor integrated circuits due to their low resistivity, strong thermal stability, good corrosion resistance, and good environmental performance.

[0003] Currently, there are various methods for preparing molybdenum targets for molybdenum metal sputtering thin films, such as sintering, electron beam melting, and hot isostatic pressing.

[0004] For example, CN111850495A discloses a semiconductor molybdenum target material, its preparation method and application. The preparation method includes sequentially performing high-purity molybdenum powder sieving and molding, cold isostatic pressing, sintering, hot rolling and annealing to obtain the semiconductor molybdenum target material. The sintering is carried out by a staged heating sintering method, in which the heating rate gradually decreases in the heating stage of 20-1500℃ and gradually increases in the heating stage of 1500-1900℃.

[0005] CN103567445A discloses a method for manufacturing a molybdenum target, comprising: providing molybdenum powder; performing a first densification treatment on the molybdenum powder using a hydrostatic pressing process to form a first molybdenum target blank; placing the first molybdenum target blank into a sleeve and evacuating it under vacuum; performing a second densification treatment on the first molybdenum target blank within the sleeve using a cold isostatic pressing process to form a second molybdenum target blank; after the second densification treatment, removing the sleeve and performing a third densification treatment on the second molybdenum target blank using an induction sintering process to form a third molybdenum target blank; after the third densification treatment, rolling the third molybdenum target blank using a hot rolling process to form a fourth molybdenum target blank; and after the hot rolling process, annealing the fourth molybdenum target blank to form a molybdenum target.

[0006] Although existing preparation processes have achieved efficient preparation of molybdenum sputtering targets, the prepared molybdenum sputtering targets still have defects such as surface or internal pores, which are not conducive to stable and efficient sputtering coating, and the preparation process is relatively complex. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing molybdenum material, so as to solve the defects of surface or internal pores in molybdenum target material products and the relatively complex preparation process.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] This invention provides a method for preparing molybdenum material, the method comprising:

[0010] The molybdenum powder is cold-pressed to obtain a green body;

[0011] The blank is sintered to obtain molybdenum material;

[0012] The particle size of the molybdenum powder includes: 1-10μm molybdenum powder, 15-25μm molybdenum powder, and 60-70μm molybdenum powder;

[0013] Ultrasonication is used during the sintering process.

[0014] The preparation method provided by this invention achieves the preparation of molybdenum material with virtually no pore defects and fine grains by using powder gradation combined with ultrasound during sintering, while still maintaining good performance and significantly improving the utilization rate of molybdenum material.

[0015] As a preferred embodiment of the present invention, the molybdenum powder comprises, by mass percentage: 2-10% 1-10μm molybdenum powder, 40-50% 15-25μm molybdenum powder, and the remainder being 60-70μm molybdenum powder.

[0016] As a preferred technical solution of the present invention, the cold pressing includes: increasing the pressure to 180-200MPa at 0.4-1.4MPa / s and holding the pressure for 800-900s.

[0017] As a preferred technical solution of the present invention, the sintering includes: a first heat preservation, a second heat preservation, and a third heat preservation performed sequentially.

[0018] Preferably, the sintering is carried out under a protective atmosphere.

[0019] As a preferred technical solution of the present invention, the insulation temperature of the first insulation is 800-1000℃.

[0020] Preferably, the heat preservation time of the first heat preservation is 1-2 hours.

[0021] As a preferred embodiment of the present invention, the first insulation is supplemented with a power density of 0.1-0.3 W / cm². 2 Ultrasound with a frequency of 10-15kHz.

[0022] As a preferred embodiment of the present invention, the insulation temperature of the second insulation is 1200-1500℃.

[0023] Preferably, the heat preservation time for the second heat preservation is 1-2 hours.

[0024] As a preferred embodiment of the present invention, the second insulation is supplemented with a power density of 0.4-0.8 W / cm². 2 Ultrasound with a frequency of 20-40kHz.

[0025] As a preferred embodiment of the present invention, the insulation temperature of the third insulation is 1600-1800℃.

[0026] Preferably, the third insulation time is 1.5-3 hours.

[0027] As a preferred embodiment of the present invention, the third insulation is supplemented with a power density of 0.4-0.5 W / cm². 2 Ultrasound with a frequency of 2-7kHz.

[0028] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0029] The preparation method provided by this invention achieves the preparation of molybdenum material with virtually no porosity defects and fine grains by using powder gradation combined with ultrasonication during sintering. The density of the molybdenum material is ≥99.18%, and the grain size is ≤27μm, while still maintaining good performance and significantly improving the utilization rate of molybdenum material. Furthermore, the segmented heat preservation and specific ultrasonication process during sintering result in a density of ≥99.99% and a grain size of ≤20μm for the obtained molybdenum material.

[0030] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0031] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0032] Currently, there are various methods for preparing molybdenum targets for molybdenum metal sputtering thin films, such as sintering, electron beam melting, and hot isostatic pressing. Although existing preparation processes achieve efficient preparation of molybdenum targets, the prepared targets still have defects such as surface or internal pores, which are detrimental to the stable and efficient sputtering deposition. Therefore, this invention provides a method for preparing molybdenum targets that achieves the preparation of virtually pore-free molybdenum targets by employing powder gradation combined with ultrasonication during sintering, while still maintaining good performance and significantly improving the utilization rate of molybdenum targets. The specific details are as follows:

[0033] I. This embodiment provides a method for preparing molybdenum material, the method comprising:

[0034] The molybdenum powder is cold-pressed to obtain a green body;

[0035] The blank is sintered to obtain molybdenum material;

[0036] The particle size of the molybdenum powder includes: 1-10μm molybdenum powder, 15-25μm molybdenum powder, and 60-70μm molybdenum powder;

[0037] Ultrasonication is used during the sintering process.

[0038] The molybdenum powder, by mass percentage, comprises: 2-10% 1-10μm molybdenum powder, 40-50% 15-25μm molybdenum powder, and the remainder is 60-70μm molybdenum powder.

[0039] In this invention, the particle size of the molybdenum powder can be limited to an aggregate of particles of any single size within a certain range, or it can be an aggregate of particles of all sizes within a certain range.

[0040] In this invention, the purity of the molybdenum powder used is ≥99.9%.

[0041] The cold pressing includes: increasing the pressure from 0.4-1.4 MPa / s to 180-200 MPa and holding the pressure for 800-900 seconds.

[0042] In this invention, the pressure increase rate of cold pressing is 0.4-1.4 MPa, for example, it can be 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa or 1.4 MPa, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0043] In this invention, the cold pressing pressure is 180-200 MPa, for example, it can be 180 MPa, 182 MPa, 184 MPa, 186 MPa, 188 MPa, 190 MPa, 192 MPa, 194 MPa, 196 MPa, 198 MPa or 200 MPa, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0044] In this invention, the holding time for cold pressing is 800-900s, for example, it can be 800s, 810s, 820s, 830s, 840s, 850s, 860s, 870s, 880s, 890s or 900s, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0045] In this invention, molybdenum powder is placed in a mold for pre-forming during the cold pressing process. The shape of the mold is specifically selected according to the shape of the final target material, such as a circular mold or a square mold.

[0046] The sintering process includes: a first heat preservation, a second heat preservation, and a third heat preservation performed sequentially.

[0047] The sintering is carried out under a protective atmosphere.

[0048] In this invention, the protective atmosphere can be selected as an inert atmosphere or a hydrogen atmosphere to avoid oxidation of the raw materials during the sintering process.

[0049] The insulation temperature of the first insulation is 800-1000℃, for example, it can be 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃ or 1000℃, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0050] The insulation time of the first insulation is 1-2 hours, for example, it can be 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0051] The first insulation layer is supplemented with a power density of 0.1-0.3 W / cm². 2 Ultrasound with a frequency of 10-15kHz.

[0052] In this invention, the power density of the ultrasound during the first heat preservation is 0.1-0.3 W / cm². 2 For example, it could be 0.1 W / cm 2 0.12W / cm 2 0.14W / cm 2 0.16W / cm 2 0.18W / cm 2 0.2W / cm 2 0.22W / cm 2 0.24W / cm 2 0.26W / cm 2 0.28W / cm 2 Or 0.3W / cm 2 The values ​​may include, but are not limited to, the listed values; other unlisted values ​​within this range also meet the requirements.

[0053] In this invention, the frequency of the ultrasound in the first heat preservation is 10-15kHz, for example, it can be 10kHz, 10.5kHz, 11kHz, 11.5kHz, 12kHz, 12.5kHz, 13kHz, 13.5kHz, 14kHz, 14.5kHz or 15kHz, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0054] The insulation temperature of the second insulation is 1200-1500℃, for example, it can be 1200℃, 1230℃, 1260℃, 1290℃, 1320℃, 1350℃, 1380℃, 1410℃, 1440℃, 1470℃ or 1500℃, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0055] The second heat preservation time is 1-2 hours, for example, it can be 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0056] The second insulation layer is supplemented with a power density of 0.4-0.8 W / cm². 2 Ultrasound with a frequency of 20-40kHz.

[0057] In this invention, the power density of the ultrasound in the second insulation process is 0.4-0.8 W / cm². 2 For example, it could be 0.4 W / cm 2 0.44W / cm 2 0.48W / cm 2 0.52W / cm 2 0.56W / cm 2 0.6W / cm 2 0.64W / cm 2 0.68W / cm 2 0.72W / cm 2 0.76W / cm 2 Or 0.8W / cm 2 The values ​​may include, but are not limited to, the listed values; other unlisted values ​​within this range also meet the requirements.

[0058] In this invention, the frequency of the ultrasound in the second heat preservation is 20-40kHz, for example, it can be 20kHz, 22kHz, 24kHz, 26kHz, 28kHz, 30kHz, 32kHz, 34kHz, 36kHz, 38kHz or 40kHz, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0059] The insulation temperature of the third insulation is 1600-1800℃, for example, it can be 1600℃, 1620℃, 1640℃, 1660℃, 1680℃, 1700℃, 1720℃, 1740℃, 1760℃, 1780℃ or 1800℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0060] The insulation time of the third insulation is 1.5-3 hours, for example, it can be 1.5 hours, 1.65 hours, 1.8 hours, 1.95 hours, 2.1 hours, 2.25 hours, 2.4 hours, 2.55 hours, 2.7 hours, 2.85 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0061] The third insulation layer is supplemented with a power density of 0.4-0.5 W / cm². 2 Ultrasound with a frequency of 2-7kHz.

[0062] In this invention, the power density of the ultrasound in the third insulation process is 0.4-0.5 W / cm². 2 For example, it could be 0.4 W / cm 2 0.41W / cm 2 0.42W / cm 2 0.43W / cm 2 0.44W / cm 2 0.45W / cm 2 0.46W / cm 2 0.47W / cm 2 0.48W / cm 2 0.49W / cm 2 Or 0.5W / cm 2 The values ​​may include, but are not limited to, the listed values; other unlisted values ​​within this range also meet the requirements.

[0063] In this invention, the frequency of the ultrasound in the third heat preservation is 2-7kHz, for example, it can be 2kHz, 2.5kHz, 3kHz, 3.5kHz, 4kHz, 4.5kHz, 5kHz, 5.5kHz, 6kHz, 6.5kHz or 7kHz, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0064] III. To illustrate the superior properties of the molybdenum material obtained by the preparation method provided by the present invention, the following examples are used for explanation:

[0065] Example 1

[0066] This embodiment provides a method for preparing molybdenum material, the method comprising:

[0067] The molybdenum powder is cold-pressed to obtain a green body;

[0068] The blank is sintered to obtain molybdenum material;

[0069] The molybdenum powder, by mass percentage, comprises: 5% 1-10μm molybdenum powder, 45% 15-25μm molybdenum powder, and the remainder is 60-70μm molybdenum powder;

[0070] The cold pressing includes: increasing the pressure to 190MPa at 1MPa / s and holding the pressure for 850s;

[0071] The sintering process includes: a first holding, a second holding, and a third holding in sequence; the sintering is carried out under a protective atmosphere (nitrogen); the first holding temperature is 900℃, and the holding time is 1.5h; the first holding is supplemented with a power density of 0.2W / cm³. 2 The second insulation uses ultrasound at a frequency of 12 kHz; the insulation temperature is 1350℃, and the insulation time is 1.5 hours; the second insulation is supplemented with a power density of 0.6 W / cm². 2 The frequency is 30kHz ultrasound; the third insulation has an insulation temperature of 1700℃ and an insulation time of 2 hours; the third insulation is supplemented with a power density of 0.45W / cm². 2 Ultrasound with a frequency of 4kHz.

[0072] Example 2

[0073] This embodiment provides a method for preparing molybdenum material, the method comprising:

[0074] The molybdenum powder is cold-pressed to obtain a green body;

[0075] The blank is sintered to obtain molybdenum material;

[0076] The molybdenum powder, by mass percentage, comprises: 2% 1-10μm molybdenum powder, 50% 15-25μm molybdenum powder, and the remainder is 60-70μm molybdenum powder;

[0077] The cold pressing includes: increasing the pressure from 0.4 MPa / s to 180 MPa and holding the pressure for 900 seconds;

[0078] The sintering process includes: a first heat treatment, a second heat treatment, and a third heat treatment performed sequentially; the sintering is carried out under a protective atmosphere (nitrogen); the first heat treatment is performed at a temperature of 800°C for 1 hour; the first heat treatment is supplemented with a power density of 0.1 W / cm³. 2 The second insulation uses ultrasound at a frequency of 15 kHz; the insulation temperature is 1200℃, and the insulation time is 1 hour; the second insulation is supplemented with a power density of 0.4 W / cm². 2 The ultrasonic wave has a frequency of 40 kHz; the third insulation has a insulation temperature of 1600℃ and an insulation time of 1.5 h; the third insulation is supplemented with a power density of 0.5 W / cm². 2 Ultrasound with a frequency of 2kHz.

[0079] Example 3

[0080] This embodiment provides a method for preparing molybdenum material, the method comprising:

[0081] The molybdenum powder is cold-pressed to obtain a green body;

[0082] The blank is sintered to obtain molybdenum material;

[0083] The molybdenum powder, by mass percentage, comprises: 10% 1-10μm molybdenum powder, 40% 15-25μm molybdenum powder, and the remainder is 60-70μm molybdenum powder;

[0084] The cold pressing includes: increasing the pressure from 1.4 MPa / s to 200 MPa and holding the pressure for 800 seconds;

[0085] The sintering process includes: a first heat treatment, a second heat treatment, and a third heat treatment sequentially; the sintering is carried out under a protective atmosphere (nitrogen); the first heat treatment is performed at a temperature of 1000℃ for 2 hours; the first heat treatment is supplemented with a power density of 0.3 W / cm³. 2 The second insulation uses ultrasound at a frequency of 10 kHz; the insulation temperature is 1500℃, and the insulation time is 2 hours; the second insulation is supplemented with a power density of 0.8 W / cm². 2 The frequency is 20kHz ultrasound; the third insulation has an insulation temperature of 1800℃ and an insulation time of 3 hours; the third insulation is supplemented with a power density of 0.4W / cm². 2 Ultrasound with a frequency of 7 kHz.

[0086] Example 4

[0087] The only difference from Example 1 is that: instead of the first heat preservation, the temperature is directly raised to the heat preservation temperature of the second heat preservation for heat preservation.

[0088] Example 5

[0089] The only difference from Example 1 is that: no second heat preservation is performed, and after the first heating, the temperature is directly raised to the heat preservation temperature of the third heat preservation for heat preservation.

[0090] Example 6

[0091] The only difference from Example 1 is that ultrasound is not used in the first insulation.

[0092] Example 7

[0093] The only difference from Example 1 is that ultrasound is not used in the second insulation.

[0094] Example 8

[0095] The only difference from Example 1 is that ultrasound is not used in the third insulation.

[0096] Comparative Example 1

[0097] The only difference from Example 1 is that ultrasound is not used during sintering.

[0098] Comparative Example 2

[0099] The only difference from Example 1 is that the particle size of the molybdenum powder used is 1-10 μm.

[0100] Comparative Example 3

[0101] The only difference from Example 1 is that the particle size of the molybdenum powder used is 15-25 μm.

[0102] Comparative Example 4

[0103] The only difference from Example 1 is that the particle size of the molybdenum powder used is 60-70 μm.

[0104] Comparative Example 5

[0105] The only difference from Example 1 is that the molybdenum powder, by mass percentage, comprises: 5% 10-15μm molybdenum powder, 45% 15-25μm molybdenum powder, and the remainder is 60-70μm molybdenum powder.

[0106] Comparative Example 6

[0107] The only difference from Example 1 is that the molybdenum powder, by mass percentage, comprises: 5% 1-10μm molybdenum powder, 45% 30-40μm molybdenum powder, and the remainder is 60-70μm molybdenum powder.

[0108] Comparative Example 7

[0109] The only difference from Example 1 is that the molybdenum powder, by mass percentage, comprises: 5% 1-10μm molybdenum powder, 45% 15-25μm molybdenum powder, and the remainder is 40-50μm molybdenum powder.

[0110] Comparative Example 8

[0111] The only difference from Example 1 is that the molybdenum powder, by mass percentage, comprises 5% 1-10μm molybdenum powder and the remainder is 60-70μm molybdenum powder.

[0112] Comparative Example 9

[0113] The only difference from Example 1 is:

[0114] The molybdenum powder comprises, by weight percentage: 45% 15-25μm molybdenum powder and the remainder is 60-70μm molybdenum powder.

[0115] Comparative Example 10

[0116] The only difference from Example 1 is:

[0117] The molybdenum powder comprises, by weight percentage: 10% 1-10μm molybdenum powder and 90% 15-25μm molybdenum powder.

[0118] The molybdenum materials obtained in the above embodiments and comparative examples were subjected to performance testing, and the results are shown in Table 1 below.

[0119] Table 1

[0120]

[0121] In the table:

[0122] Density refers to the ratio of the density of the obtained molybdenum material measured using the basket method disclosed in standard GB / T 3850-2015 "Method for Measurement of Density of Dense Sintered Metal Materials and Hard Alloys" to the true density of molybdenum.

[0123] Grain size: The grain size was determined according to the cross-sectional method disclosed in the national standard GB / T 6394-2017 "Method for Determination of Average Grain Size of Metals".

[0124] As shown in Table 1, the preparation method provided by the present invention achieves the preparation of molybdenum material with virtually no pore defects and fine grains by using powder gradation combined with ultrasound in sintering, while still having good performance and significantly improving the utilization rate of molybdenum material. The density of the obtained molybdenum material is ≥99.99% and the grain size is ≤20μm.

[0125] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0126] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0127] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a molybdenum material, characterized in that, The preparation method includes: The molybdenum powder is cold-pressed to obtain a green body; The blank is sintered to obtain molybdenum material; The particle size of the molybdenum powder includes: 1-10μm molybdenum powder, 15-25μm molybdenum powder, and 60-70μm molybdenum powder; Ultrasonication is used during the sintering process.

2. The preparation method according to claim 1, characterized in that, The molybdenum powder, by mass percentage, comprises: 2-10% 1-10μm molybdenum powder, 40-50% 15-25μm molybdenum powder, and the remainder is 60-70μm molybdenum powder.

3. The preparation method according to claim 1, characterized in that, The cold pressing includes: increasing the pressure from 0.4-1.4 MPa / s to 180-200 MPa and holding the pressure for 800-900 seconds.

4. The preparation method according to claim 1, characterized in that, The sintering process includes: a first heat preservation, a second heat preservation, and a third heat preservation in sequence; Preferably, the sintering is carried out under a protective atmosphere.

5. The preparation method according to claim 4, characterized in that, The insulation temperature of the first insulation is 800-1000℃; Preferably, the heat preservation time of the first heat preservation is 1-2 hours.

6. The preparation method according to claim 4, characterized in that, The first insulation is supplemented with a power density of 0.1-0.3 W / cm². 2 Ultrasound with a frequency of 10-15kHz.

7. The preparation method according to claim 4, characterized in that, The insulation temperature of the second insulation is 1200-1500℃; Preferably, the heat preservation time for the second heat preservation is 1-2 hours.

8. The preparation method according to claim 4, characterized in that, The second insulation is supplemented with a power density of 0.4-0.8 W / cm². 2 Ultrasound with a frequency of 20-40kHz.

9. The preparation method according to claim 4, characterized in that, The insulation temperature of the third insulation is 1600-1800℃; Preferably, the third insulation time is 1.5-3 hours.

10. The preparation method according to claim 4, characterized in that, The third insulation is supplemented with a power density of 0.4-0.5 W / cm². 2 Ultrasound with a frequency of 2-7kHz.

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