Preparation method of MoTi alloy

Abstract

The invention provides a preparation method of MoTi alloy, and belongs to the technical field of alloy. According to the preparation method, the Ti powder and the Mo powder are mixed and then subjected to sheathing assembly, degassing and hot isostatic pressing sintering to prepare the MoTi alloy target material, and compared with a traditional hot pressing sintering method, the obtained MoTi alloy is high in density, free of defects such as air holes and cracks in the internal structure, uniform and fine in grain structure, good in conductivity and excellent in sputtering performance; the method is suitable for preparing films in solar cells, photoelectric devices, semiconductor devices and the like.

Description

Technical Field

[0001] The present application relates to the technical field of alloys, and in particular to a method for preparing a MoTi alloy. Background Art

[0002] MoTi alloy target has become an important material in the field of sputtering coating due to its excellent performance, sophisticated preparation process and wide application fields. It is often used as a precursor material in the sputtering coating process to prepare thin films with excellent electrical, magnetic and optical properties. It has important applications in solar cells, optoelectronic devices, semiconductor devices and other fields. Therefore, the requirements for MoTi alloy target are relatively high, such as high density, no defects such as pores and cracks in the internal structure, uniform target grain size, and uniform distribution of Mo and Ti. Summary of the invention

[0003] Based on the defects of the prior art, the purpose of this application is to provide a method for preparing a MoTi alloy, wherein the prepared MoTi alloy has high density, no defects such as pores and cracks in the internal structure, uniform and fine grain structure, good electrical conductivity and excellent sputtering performance.

[0004] In order to achieve the above object, the present application provides a method for preparing a MoTi alloy, comprising the following steps:

[0005] Ti powder and Mo powder are mixed, and then packaged, degassed and hot isostatically pressed to obtain MoTi alloy.

[0006] At present, hot pressing sintering is mainly used to prepare MoTi alloy, but the pressure is applied in one direction during the hot pressing sintering process, which makes the pressure distribution in the blank uneven and the density of the obtained MoTi alloy insufficient. The present application adopts hot isostatic pressing sintering (also known as high temperature isostatic pressing sintering, Hot Isostatic Pressing Sintering, referred to as HIP) to prepare MoTi alloy. During the hot isostatic pressing sintering process, the blank is subjected to isostatic pressure in all directions, and the combined effect of high temperature and high pressure promotes the densification of the blank, so that the obtained MoTi alloy has high density, no defects such as pores and cracks in the internal structure, uniform and fine grain structure, good electrical conductivity, and excellent sputtering performance.

[0007] Preferably, the hot isostatic pressing sintering satisfies: the sintering temperature is 900° C.-1130° C., the sintering pressure is 110-160 MPa, and the holding time is 3-5 h.

[0008] When the sintering temperature, sintering pressure and holding time of the hot isostatic pressing sintering are within the above range, the density of the obtained MoTi alloy target is higher, the grain structure is more uniform and fine, and the electrical conductivity is better. The sintering temperature can be selected as 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1130°C or any two of the above values; the sintering pressure can be selected as 110MPa, 120MPa, 130MPa, 140MPa, 150MPa, 160MPa or any two of the above values; the sintering time can be selected as 3h, 3.5h, 4h, 4.5h, 5h or any two of the above values.

[0009] Preferably, the heating rate during the hot isostatic pressing sintering process is 1-5°C / min.

[0010] Preferably, the vacuum degree in the package after degassing is less than 4×10 -3 Pa. When the vacuum degree in the package after degassing is less than 4×10 -3 Pa, such as 3×10 -3 Pa, 1×10 -3 Pa, 0.1×10 -3 Pa, 0.01×10 -3 Pa, etc., the hot isostatic pressing sintering process is smoother, and the density, uniformity and refinement of the grain structure and conductivity of the obtained target material are better. In some embodiments, the vacuum degree in the package after degassing is 1×10 -3 -4×10 -3 Pa.

[0011] Preferably, the degassing temperature is 450-550°C.

[0012] The degassing time can be determined according to the target vacuum degree in the package after degassing and the degassing temperature. Preferably, the degassing time is 3-6 hours.

[0013] The ratio of the Ti powder to the Mo powder will affect the crystal form of the MoTi alloy obtained, and the ratio of the two can be adjusted according to the crystal form of the target MoTi alloy. In some embodiments, the weight of the Ti powder is 20%-40% of the total weight of the Ti powder and the Mo powder, such as 20%, 25%, 30%, 35%, 40% or an interval formed by any two of the above values.

[0014] Preferably, the purity of the Ti powder is greater than 99.95wt.% and less than or equal to 100wt.%, and the particle size Dv50 is 30-45μm; the purity of the Mo powder is greater than 99.95wt.% and less than or equal to 100wt.%, and the particle size Dv50 is 5-8μm. The purity and particle size Dv50 of the Ti powder and the Mo powder will affect the purity of the obtained MoTi alloy. Controlling the purity and particle size Dv50 of the two within the above range is conducive to obtaining a higher purity MoTi alloy. Among them, the purity of the Ti powder can be selected as 99.96wt.%, 99.97wt.%, 99.98wt.%, 99.99wt.% or an interval formed by any two of the above values; the particle size Dv50 of the Ti powder can be selected as 30μm, 33μm, 35μm, 37μm, 40μm, 42μm, 45μm or an interval formed by any two of the above values; the purity of the Mo powder can be selected as 99.96wt.%, 99.97wt.%, 99.98wt.%, 99.99wt.% or an interval formed by any two of the above values; the particle size Dv50 of the Mo powder can be selected as 5μm, 6μm, 7μm, 8μm or an interval formed by any two of the above values.

[0015] Preferably, the ball milling is carried out under an inert atmosphere, and the ball-to-material ratio is 1:1-1:3, the rotation speed is 300-400 r / min, and the ball milling time is 10-18 h.

[0016] Preferably, the density of the MoTi alloy is ≥99%, the average grain size of Mo is <10 μm, the average grain size of Ti is less than ≤50 μm, the weight percentage of Ti is 20%-40%, and the purity of the MoTi alloy is ≥99.95%. Among them, the density of the MoTi alloy target can be selected as 99.0%, 99.2%, 99.6%, 99.8%, 99.9% or an interval range formed by any two of the above values; the average grain size of Mo in the MoTi alloy target can be selected as 5μm, 6μm, 7μm, 8μm, 9μm or an interval range formed by any two of the above values; the average grain size of Ti in the MoTi alloy can be selected as 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm or an interval range formed by any two of the above values; the purity of the MoTi alloy can be selected as 99.95%, 99.96%, 99.97%, 99.98%, 99.99% or an interval range formed by any two of the above values.

[0017] More preferably, the density of the MoTi alloy is 99.1%-99.8%, the average grain size of Mo is 5-9 μm, the average grain size of Ti is 46-50 μm, and the purity of the MoTi alloy is 99.95%-99.99%.

[0018] Preferably, the method further comprises the following steps: subjecting the MoTi alloy to grinding to obtain a MoTi alloy target.

[0019] Preferably, the grinding machine processing meets the following requirements: a feed rate of 2-10 μm per time, and an EDM wire cutting rate of 2-5 mm / min.

[0020] Compared with the prior art, the beneficial effect of the present application is that: the present application prepares MoTi alloy by mixing Ti powder and Mo powder and then performing packaging assembly, degassing and hot isostatic pressing sintering. Compared with the traditional hot pressing sintering method, the obtained MoTi alloy has high density, no defects such as pores and cracks in the internal structure, uniform and fine grain structure, good electrical conductivity, excellent sputtering performance, and is suitable for preparing thin films such as solar cells, optoelectronic devices, and semiconductor devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Flow chart of the MoTi alloy target material processing process in Example 1;

[0022] Figure 2 This is a schematic diagram of packaging assembly in Example 1;

[0023] Figure 3 This is a photo of the MoTi alloy target obtained in Example 1. DETAILED DESCRIPTION

[0024] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in conjunction with specific embodiments and comparative examples, the purpose of which is to understand the content of the present application in detail, rather than to limit the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application. The experimental reagents and instruments involved in the implementation of this application are all commonly used ordinary reagents and instruments unless otherwise specified. In the present application, the technical features described in an open manner include closed technical schemes composed of the listed features, and also include open technical schemes containing the listed features.

[0025] Example 1

[0026] This embodiment provides a method for preparing a MoTi alloy target, and its flow chart is as follows: Figure 1 As shown, the following steps are included:

[0027] (1) Powder mixing: Ti powder (purity 99.6wt.%, particle size Dv50 33.4μm) and Mo powder (purity 99.95wt.%, particle size Dv50 6.3μm) were poured into a 10L polyurethane powder mixing barrel at a ratio of Ti powder weight to 30% of the total weight of Ti powder and Mo powder, and powder mixing balls were added at a ball-to-material ratio (weight ratio) of 1:2. High-purity Ar gas (purity 99.99%, v / v, the same below) was filled in for 30 minutes and then the powders were mixed in a drum ball mill at a speed of 400r / min for 12h to obtain MoTi mixed powder;

[0028] (2) Packaging assembly: The packaging is designed according to the size of the finished product. The packaging material is low carbon steel or stainless steel. Figure 2 First, pad graphite paper and partitions on the inner wall of the bag, weigh the required weight of MoTi mixed powder, put it into the bag in batches for compaction and flattening, then pad graphite paper and partitions on the powder plane, weld the bag cover with degassing port to the top of the bag, and weld the degassing pipe to the degassing port;

[0029] (3) Degassing: Use a helium mass spectrometer to detect leaks on the package. After the leak detection is OK, heat up and degas. The degassing temperature is 450℃ and the degassing time is 5h. When the vacuum degree inside the package is 3×10 -3 Pa, flatten the degassing pipe near the package and cut off the excess part to form a closed vacuum environment in the package;

[0030] (4) HIP sintering: The degassed package is placed in a hot isostatic pressing sintering furnace, and vacuuming, pressurizing, sintering, cooling and pressure recovery are performed in sequence. During the sintering process, the heating rate is 3°C / min, the sintering temperature is 1100°C, the sintering pressure is 150MPa, and the holding time is 5h. During the cooling and pressure recovery process, when the temperature is less than 100°C and the pressure of the hot isostatic pressing sintering furnace is 0MPa, the package meets the furnace discharge standard.

[0031] (5) Machining: Remove the graphite paper on the surface of the target material and grind it according to the drawing requirements. The feed amount of the grinder is 5μm, and the wire cutting rate of the electric spark wire cutting is 3mm / min. The target blank is machined to the qualified size and relevant defects and density tests are carried out. If no abnormalities are found, it is vacuum packaged.

[0032] Example 2

[0033] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the sintering pressure during the sintering process is 140 MPa and the holding time is 4 h.

[0034] Example 3

[0035] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the sintering pressure during the sintering process is 140 MPa.

[0036] Example 4

[0037] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the sintering temperature during the sintering process is 800° C.

[0038] Example 5

[0039] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the sintering temperature during the sintering process is 900° C.

[0040] Example 6

[0041] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the sintering temperature during the sintering process is 1130° C.

[0042] Example 7

[0043] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the sintering temperature during the sintering process is 1200° C.

[0044] Example 8

[0045] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the sintering pressure during the sintering process is 100 MPa.

[0046] Example 9

[0047] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the sintering pressure during the sintering process is 110 MPa.

[0048] Example 10

[0049] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the sintering pressure during the sintering process is 160 MPa.

[0050] Embodiment 11

[0051] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the sintering pressure during the sintering process is 180 MPa.

[0052] Example 12

[0053] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the weight of Ti powder in step (1) is 20% of the total weight of Ti powder and Mo powder, the particle size Dv50 of Ti powder is 30 μm, and the particle size Dv50 of Mo powder is 8 μm.

[0054] Embodiment 13

[0055] This embodiment provides a method for preparing a MoTi alloy target, which is different from Embodiment 1 in that the weight of Ti powder in step (1) is 40% of the total weight of Ti powder and Mo powder, the particle size Dv50 of Ti powder is 45 μm, and the particle size Dv50 of Mo powder is 5 μm.

[0056] Comparative Example 1

[0057] The present comparative example provides a method for preparing a MoTi alloy target, which is different from that of Example 1 in that the MoTi mixed powder obtained in step (1) is not subjected to packaging assembly, degassing and HIP sintering. Instead, the MoTi mixed powder is loaded into a graphite mold, placed in a vacuum hot pressing sintering furnace, heated to 1350° C. at a heating rate of 3° C. / min, pressurized to 40 MPa, and kept at this temperature for 2 h. After the end of the heat preservation and pressure holding, the target is taken out of the furnace after the temperature is lowered, and machined according to the grinding machine processing method of Example 1.

[0058] Comparative Example 2

[0059] The present comparative example provides a method for preparing a MoTi alloy target, which is different from Example 1 in that the MoTi mixed powder obtained in step (1) is not subjected to packaging assembly, degassing and HIP sintering. Instead, the MoTi mixed powder is loaded into a graphite mold, placed in a vacuum hot pressing sintering furnace, heated to 1300°C at a heating rate of 3°C / min, pressurized to 35MPa, and kept at this temperature for 2h. After the end of the heat preservation and pressure holding, the target is taken out of the furnace after the temperature is lowered, and machined according to the grinding machine processing method of Example 1.

[0060] Comparative Example 3

[0061] The present comparative example provides a method for preparing a MoTi alloy target, which is different from that of Example 1 in that the MoTi mixed powder obtained in step (1) is not subjected to packaging assembly, degassing and HIP sintering. Instead, the MoTi mixed powder is loaded into a graphite mold, placed in a vacuum hot pressing sintering furnace, heated to 1100°C at a heating rate of 3°C / min, pressurized to 150 MPa, and kept at this temperature for 5 hours. After the end of the heat preservation and pressure holding, the target is taken out of the furnace after the temperature is lowered, and machined according to the grinding machine processing method of Example 1.

[0062] Test Case

[0063] The MoTi alloy targets obtained in the above embodiments and comparative examples were tested as follows:

[0064] Density: Archimedean drainage method;

[0065] Mo average grain size and Ti average grain size: using SEM and the straight line intercept method;

[0066] Target Ti content: ICP-OES;

[0067] Target purity: ICP-OES.

[0068] The test results are shown in Table 1.

[0069] Table 1

[0070]

[0071] It can be seen from the above data that the MoTi alloy target prepared by the method of the present application has a density ≥99%, a uniform and fine grain size, an average Mo grain size <10μm, an average Ti grain size less than ≤50μm; a Ti content of 20%-40%; and a target purity ≥99.95%.

[0072] Comparative Examples 1 to 3 adopt the traditional hot pressing sintering method to prepare MoTi alloy targets, resulting in low density of the targets and large average Ti grain size.

[0073] From the comparison between Examples 1 and 4 to 7, it can be seen that when the sintering temperature is in the range of 900 to 1130°C, the density of the obtained target material is significantly better, and the balance between density and grain size is better; from the comparison between Examples 1 and 8 to 11, it can be seen that when the sintering pressure is in the range of 110 to 160 MPa, the density of the obtained target material is significantly better, and the balance between density and grain size is better.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present application.

Claims

1. A method for preparing a MoTi alloy, characterized in that: The following steps are involved: Ti powder and Mo powder are mixed, and then packaged, degassed and hot isostatically pressed to obtain MoTi alloy.

2. The method for preparing the MoTi alloy according to claim 1, characterized in that: The hot isostatic pressing sintering meets the following conditions: sintering temperature is 900° C.-1130° C., sintering pressure is 110-160 MPa, and holding time is 3-5 h.

3. The method for preparing the MoTi alloy according to claim 1, characterized in that: The vacuum degree in the package after degassing is less than 4×10 -3 Pa; preferably 1×10 -3 -4×10 -3 Pa.

4. The method for preparing the MoTi alloy according to claim 1, characterized in that: The degassing temperature is 450-550°C.

5. The method for preparing the MoTi alloy according to claim 1, characterized in that: The weight of the Ti powder is 20%-40% of the total weight of the Ti powder and the Mo powder.

6. The method for preparing the MoTi alloy according to claim 1, characterized in that: The purity of the Ti powder is greater than 99.95wt.% and less than or equal to 100wt.%, and the particle size Dv50 is 30-45μm; the purity of the Mo powder is greater than 99.95wt.% and less than or equal to 100wt.%, and the particle size Dv50 is 5-8μm.

7. The method for preparing the MoTi alloy according to claim 1, characterized in that: The ball milling is carried out under an inert atmosphere, with a ball-to-material ratio of 1:1-1:3, a rotation speed of 300-400 r / min, and a ball milling time of 10-18 h.

8. The method for preparing the MoTi alloy according to claim 1, characterized in that: The density of the MoTi alloy is ≥99%, the average grain size of Mo is <10 μm, the average grain size of Ti is less than ≤50 μm, the weight percentage of Ti is 20%-40%, and the purity of the MoTi alloy is ≥99.95%.

9. The method for preparing the MoTi alloy according to claim 8, characterized in that: The density of the MoTi alloy is 99.1%-99.8%, the average grain size of Mo is 5-9 μm, the average grain size of Ti is 46-50 μm, and the purity of the MoTi alloy is 99.95%-99.99%.

10. The method for preparing the MoTi alloy according to claim 1, characterized in that: The following steps are also included: The MoTi alloy is processed by a grinder to obtain a MoTi alloy target.

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