A method for manufacturing a molybdenum end cap and a molybdenum end cap manufactured thereby

Abstract

The application discloses a preparation method of a molybdenum end cap and the molybdenum end cap prepared thereby, and relates to the field of metal products. The preparation method of the molybdenum end cap comprises the following steps: uniformly mixing molybdenum powder, a binder and a solvent according to a weight ratio, granulating and removing the solvent to obtain molybdenum particles; the binder comprises isocyanate-terminated polyurethane prepolymer, polyglycol monomethyl ether glycidyl ether, polyvinyl butyral and a diluent according to a weight ratio of (20-30):(8-12):(35-40):100; the molybdenum particles are compression molded to obtain a molybdenum end cap before debinding; and the molybdenum end cap before debinding is subjected to debinding, wherein the debinding comprises the steps of primary debinding, secondary debinding and tertiary debinding, the temperature of the primary debinding is 560-780 DEG C, the temperature of the secondary debinding is 880-950 DEG C, and the temperature of the tertiary debinding is 1200-1300 DEG C. The application can improve the stability of the molybdenum particles forming the molybdenum end cap, and simultaneously improve the problem that organic substances are easily left in the molybdenum end cap, thereby causing the purity of the molybdenum end cap to be not high.

Description

Technical Field

[0001] This application relates to the field of metal products, and in particular to a method for preparing a molybdenum end cap and the molybdenum end cap obtained therefrom. Background Technology

[0002] Molybdenum end caps are one of the components of magnetron cathode assemblies. During the production process, molybdenum powder, binder, lubricant and solvent need to be mixed evenly, then granulated and dried to obtain molybdenum particles with larger particle sizes. The molybdenum particles are then pressed into shape to obtain molybdenum end caps before degreasing. Finally, the molybdenum end caps are degreased at high temperature to obtain molybdenum end caps with high purity and good weldability.

[0003] Currently, the commonly used binder in related technologies is polyvinyl butyral, the lubricant is organic wax, and the solvent is ethanol. However, modified polyvinyl butyral has low bonding strength to molybdenum powder, and the high proportion of fine molybdenum particles leads to poor molding stability of the molybdenum end caps. Furthermore, during the degreasing process in current technologies, binder and organic wax residues are easily left, affecting the purity of the molybdenum end caps and negatively impacting their welding stability. Summary of the Invention

[0004] In order to improve the stability of molybdenum end caps formed from molybdenum particles, and to address the problem of residual organic matter in the molybdenum end caps leading to poor welding stability, this application provides a method for preparing molybdenum end caps and the resulting molybdenum end caps.

[0005] Firstly, the method for preparing a molybdenum end cap provided in this application adopts the following technical solution:

[0006] A method for preparing a molybdenum end cap includes the following steps:

[0007] Mix molybdenum powder, binder, and solvent in a weight ratio of (45-55):(15-20):(25-30).

[0008] After uniform mixing, the mixture is granulated and the solvent is removed to obtain molybdenum particles; the binder includes isocyanate-terminated polyurethane prepolymer, polyethylene glycol monomethyl ether glycidyl ether, polyvinyl butyral and diluent, wherein the weight ratio of isocyanate-terminated polyurethane prepolymer, polyethylene glycol monomethyl ether glycidyl ether, polyvinyl butyral and diluent is (20-30):(8-12):(35-40):100;

[0009] The molybdenum particles are pressed into shape to obtain a molybdenum end cap before degreasing.

[0010] The molybdenum end cap is degreased before degreasing. The degreasing includes a first degreasing, a second degreasing and a third degreasing step. The temperature of the first degreasing is 560-780℃ and the time is 15-30s. The temperature of the second degreasing is 880-950℃ and the time is 15-30s. The temperature of the third degreasing is 1200-1300℃ and the time is 15-30s.

[0011] By adopting the above technical solution, in this application, the molybdenum end cap is prepared from molybdenum powder, a binder, and a solvent to form molybdenum particles. The binder is prepared by mixing isocyanate-terminated polyurethane prepolymer, polyethylene glycol monomethyl ether glycidyl ether, polyvinyl butyral, and a diluent. Compared with the prior art using polyvinyl butyral alone as a binder, the binder of this application improves the bonding strength between the binder and the molybdenum powder, enabling the molybdenum powder to agglomerate into molybdenum particles with stable particle size, thereby improving the stability of the molybdenum end cap formed from the molybdenum particles. Furthermore, when using the binder of this application, there is no need to add lubricants such as organic waxes or zinc stearate, which helps to improve the purity of the molybdenum end cap.

[0012] In addition, the degreasing process for molybdenum end caps is carried out in three steps. The first step degreasing temperature is controlled at 560-780℃, the second step degreasing temperature is controlled at 880-950℃, and the third step degreasing temperature is controlled at 1200-1300℃. This effectively removes organic matter from the molybdenum end caps before degreasing, improves the purity of the final molybdenum end caps, and helps to improve the welding stability of the molybdenum end caps.

[0013] In step S1, granulation and solvent removal are carried out in a centrifugal spray dryer with an inlet air temperature of 250-350℃, an outlet air temperature of 180-200℃, a feed flow rate of 20-50 g / min, and a rotation speed of 8000-10000 r / min.

[0014] Preferably, the isocyanate-terminated polyurethane prepolymer comprises raw material components polyether diol, diisocyanate, succinic dihydrazide, catalyst, and viscosity reducer, wherein the weight ratio of polyether diol, diisocyanate, succinic dihydrazide, catalyst, and viscosity reducer is (50-60):(35-40):(5.5-6.8):(0.001-0.005):20.

[0015] By adopting the above technical solution, when the isocyanate-terminated polyurethane prepolymer is prepared using polyether diol, diisocyanate, succinic dihydrazide, catalyst and viscosity reducer within the above ratio range, the binder has good dispersibility, the particle size distribution stability of the obtained molybdenum particles is further improved, and it has a further promoting effect on improving the molding stability of molybdenum end caps.

[0016] Preferably, the polyether diol is at least one of polypropylene glycol and polytetrahydrofuran diol.

[0017] Preferably, the molecular weight of the polyether diol is in the range of 1000-2000.

[0018] This application uses polyether diols with a molecular weight range of 1000-2000 to prepare isocyanate-terminated polyurethane prepolymers, which is beneficial to improving the dispersibility of the binder.

[0019] Preferably, the diisocyanate is an aliphatic diisocyanate, and the aliphatic diisocyanate is at least one of isophorone diisocyanate and hexamethylene diisocyanate.

[0020] In this application, an aliphatic diisocyanate is used as the diisocyanate, which is beneficial to improving the removal effect of the binder and plays an important role in improving the purity of the molybdenum end cap.

[0021] Preferably, the viscosity reducer is selected from any one of ethanol, acetone, and water.

[0022] In this application, the addition of a viscosity reducer can improve the stability of isocyanate-terminated polyurethane and also improve the dispersibility of the binder.

[0023] Preferably, the isocyanate-terminated polyurethane prepolymer is prepared as follows:

[0024] The polyether diol is heated to 50-55℃, then diisocyanate, succinic dihydrazide and catalyst are added, and after stirring evenly, the temperature is raised to 75-85℃ and reacted for 3-4 hours. Then, a viscosity reducer is added and stirred evenly to obtain isocyanate-terminated polyurethane prepolymer.

[0025] In this application, the isocyanate-terminated polyurethane prepolymer obtained by the above method can improve...

[0026] Preferably, the adhesive is prepared by the following method:

[0027] Dissolve polyvinyl butyral in a diluent, then add polyethylene glycol monomethyl ether glycidyl ether and isocyanate-terminated polyurethane prepolymer, stir until homogeneous, and the adhesive is obtained.

[0028] Preferably, the solvent is an ethanol solution with a mass concentration of 10%-20%.

[0029] In summary, this application includes at least the following beneficial technical effects:

[0030] (1) In this application, the molybdenum end cap is prepared from molybdenum powder, a binder, and a solvent to form molybdenum particles. The binder is prepared by mixing isocyanate-terminated polyurethane prepolymer, polyethylene glycol monomethyl ether glycidyl ether, polyvinyl butyral, and a diluent. Compared to the prior art which uses polyvinyl butyral alone as a binder, the binder in this application improves the bonding strength between the binder and the molybdenum powder, enabling the molybdenum powder to aggregate into molybdenum particles with stable particle size, thereby improving the stability of the molybdenum end cap formed from the molybdenum particles. Furthermore, when using the binder in this application, there is no need to add lubricants such as organic waxes or zinc stearate, which helps to improve the purity of the molybdenum end cap. In addition, the degreasing process for molybdenum end caps is carried out in three steps. The first step degreasing temperature is controlled at 560-780℃, the second step degreasing temperature is controlled at 880-950℃, and the third step degreasing temperature is controlled at 1200-1300℃. This effectively removes organic matter from the molybdenum end caps before degreasing, improves the purity of the final molybdenum end caps, and helps to improve the welding stability of the molybdenum end caps.

[0031] (2) In this application, when the isocyanate-terminated polyurethane prepolymer is prepared using polyether diol, diisocyanate, succinic dihydrazide, catalyst and viscosity reducer within the above-mentioned ratio range, the binder has good dispersibility and the particle size distribution stability of the obtained molybdenum particles is further improved, which further promotes the molding stability of the molybdenum end cap. Detailed Implementation

[0032] The present application will be further described below with reference to specific embodiments and comparative examples. In the following embodiments of the present application, polytetrahydrofuran glycol was purchased from Weishang Chemical, model PTMG2000; polyvinyl butyral was purchased from Wanwei, with a viscosity of 2000; and polyethylene glycol monomethyl ether glycidyl ether was purchased from Shineng, model MPEG-EPO.

[0033] Example

[0034]

Example 1

[0035] A method for preparing a molybdenum end cap includes the following steps:

[0036] S1. Mix 45kg of molybdenum powder, 15kg of binder and 25kg of ethanol evenly, and then put them into a centrifugal spray dryer to granulate and dry the molybdenum powder. The inlet air temperature of the centrifugal spray dryer is 250℃, the outlet air temperature is 200℃, the feed flow rate is 20g / min, and the rotation speed is 8000r / min to obtain molybdenum particles.

[0037] S2. Press the molybdenum particles into shape to obtain the molybdenum end cap before degreasing;

[0038] S3. Degrease the molybdenum end cap before degreasing. The degreasing process includes three steps: first degreasing, second degreasing, and third degreasing. The temperature for the first degreasing is 560℃ and the time is 30s. The temperature for the second degreasing is 880℃ and the time is 30s. The temperature for the third degreasing is 1200℃ and the time is 30s. The molybdenum end cap is then obtained.

[0039] The adhesive used in step S1 of this embodiment is prepared by the following method:

[0040] 50 kg of polytetrahydrofuran diol was heated to 50 °C, and then 35 kg of isophorone diisocyanate, 5.5 kg of ethylenediamine and 0.001 kg of dibutyltin dilaurate catalyst were added. After stirring evenly, the temperature was raised to 75 °C and reacted for 4 h. Then 20 kg of ethanol was added and stirred evenly to obtain isocyanate-terminated polyurethane prepolymer.

[0041] Dissolve 35 kg of polyvinyl butyral in 100 kg of 10% ethanol solution, then add 12 kg of polyethylene glycol monomethyl ether glycidyl ether and 30 kg of isocyanate-terminated polyurethane prepolymer, stir until homogeneous, and the adhesive can be obtained.

[0042]

Example 2

[0043] A method for preparing a molybdenum end cap includes the following steps:

[0044] S1. Mix 55kg of molybdenum powder, 20kg of binder and 30kg of ethanol evenly, and then put them into a centrifugal spray dryer to granulate and dry the molybdenum powder. The inlet air temperature of the centrifugal spray dryer is 350℃, the outlet air temperature is 180℃, the feed flow rate is 50g / min, and the rotation speed is 10000r / min to obtain molybdenum particles.

[0045] S2. Press the molybdenum particles into shape to obtain the molybdenum end cap before degreasing;

[0046] S3. Degrease the molybdenum end cap before degreasing. The degreasing process includes three steps: first degreasing, second degreasing, and third degreasing. The temperature for the first degreasing is 780℃ and the time is 15s. The temperature for the second degreasing is 950℃ and the time is 15s. The temperature for the third degreasing is 1300℃ and the time is 15s. The molybdenum end cap is then obtained.

[0047] The adhesive used in step S1 of this embodiment is prepared by the following method:

[0048] 60 kg of polytetrahydrofuran diol was heated to 55 °C, and then 40 kg of isophorone diisocyanate, 6.8 kg of ethylenediamine and 0.005 kg of dibutyltin dilaurate catalyst were added. After stirring evenly, the temperature was raised to 85 °C and reacted for 3 h. Then 20 kg of water was added and stirred evenly to obtain isocyanate-terminated polyurethane prepolymer.

[0049] Dissolve 40 kg of polyvinyl butyral in 100 kg of 20% ethanol solution, then add 8 kg of polyethylene glycol monomethyl ether glycidyl ether and 20 kg of isocyanate-terminated polyurethane prepolymer, stir until homogeneous, and the adhesive can be obtained.

[0050]

Example 3

[0051] A method for preparing a molybdenum end cap differs from that in [Example 1] in that the isocyanate-terminated polyurethane prepolymer is different.

[0052] In this embodiment, when preparing the isocyanate-terminated polyurethane prepolymer, ethylenediamine is replaced by an equal amount of succinic dihydrazide.

[0053]

Example 4

[0054] A method for preparing a molybdenum end cap differs from that in [Example 1] in that the isocyanate-terminated polyurethane prepolymer is different.

[0055] In this embodiment, when preparing the isocyanate-terminated polyurethane prepolymer, ethylenediamine is replaced by an equal amount of diterephthalic acid dihydrazide.

[0056] Comparative Example

[0057] Comparative Example 1

[0058] A method for preparing a molybdenum end cap differs from that in [Example 1] in that the adhesive composition is different.

[0059] In this comparative example, the isocyanate-terminated polyurethane prepolymer was replaced with an equal amount of polyethylene glycol monomethyl ether glycidyl ether.

[0060] Comparative Example 2

[0061] A method for preparing a molybdenum end cap differs from that in [Example 1] in that the adhesive composition is different.

[0062] In this comparative example, polyethylene glycol monomethyl ether glycidyl ether was replaced by an equal amount of isocyanate-terminated polyurethane prepolymer.

[0063] Comparative Example 3

[0064] A method for preparing a molybdenum end cap differs from that in [Example 1] in that the adhesive composition is different.

[0065] In this comparative example, the adhesive was obtained by dissolving 35 kg of polyvinyl butyral in 100 kg of a 10% ethanol solution.

[0066] Comparative Example 4

[0067] A method for preparing a molybdenum end cap differs from that in [Example 1] in that the degreasing step is different.

[0068] In this embodiment, the degreasing is performed in one step, with the temperature at 560°C and the time at 1.5 minutes.

[0069] Comparative Example 5

[0070] A method for preparing a molybdenum end cap differs from that in [Example 1] in that the degreasing step is different.

[0071] In this embodiment, the degreasing is performed in one step, with the temperature at 880°C and the time at 1.5 minutes.

[0072] Comparative Example 6

[0073] A method for preparing a molybdenum end cap differs from that in [Example 1] in that the degreasing step is different.

[0074] In this embodiment, the degreasing is performed in one step, with the temperature at 1200℃ and the time at 1.5 minutes.

[0075] Comparative Example 7

[0076] A method for preparing a molybdenum end cap differs from that in [Example 1] in that the degreasing step is different.

[0077] Degreasing includes three steps: primary degreasing, secondary degreasing, and tertiary degreasing. The primary degreasing temperature is 1200℃ and the time is 30 seconds; the secondary degreasing temperature is 880℃ and the time is 30 seconds; and the tertiary degreasing temperature is 560℃ and the time is 30 seconds.

[0078] Comparative Example 8

[0079] A method for preparing a molybdenum end cap differs from that in [Example 1] in that the degreasing step is different.

[0080] Degreasing includes three steps: primary degreasing, secondary degreasing, and tertiary degreasing. The primary degreasing temperature is 560℃ and the time is 30 seconds; the secondary degreasing temperature is 1200℃ and the time is 30 seconds; and the tertiary degreasing temperature is 1200℃ and the time is 30 seconds.

[0081] Performance testing

[0082] 1. Test the particle size distribution of molybdenum particles obtained in step S1 of each embodiment and comparative example, and record the weight percentage of molybdenum particles with a particle size less than 15 μm, a particle size between 15 μm and 30 μm, and a particle size greater than 30 μm. Among them, when the particle size of molybdenum particles is between 15 μm and 30 μm, the performance of molybdenum particles forming molybdenum end caps is the most stable.

[0083] 2. Calculate the degreasing rate of the molybdenum end caps obtained in step S2 of each embodiment and comparative example. A higher degreasing rate indicates lower adhesive residue in the molybdenum end cap, resulting in better weldability and electrical conductivity. The degreasing rate is calculated as: (Weight of molybdenum end cap before degreasing - Weight of molybdenum end cap) / (Weight of molybdenum end cap before degreasing - Weight of molybdenum powder) * 100.

[0084] Table 1. Particle size range of molybdenum particles

[0085]

[0086] Table 2 Degreasing rate of molybdenum end cap

[0087]

[0088]

[0089] Based on the above-mentioned Examples 1 and Comparative Examples 1-3 of this application and the data in Tables 1-2, it can be seen that when the binder is prepared by mixing isocyanate-terminated polyurethane prepolymer, polyethylene glycol monomethyl ether glycidyl ether, polyvinyl butyral and diluent, the binder has the advantages of both good dispersibility and good adhesion, which is beneficial to increasing the proportion of molybdenum particles with a particle size range of 15-30 μm and promotes the molding stability of molybdenum end caps.

[0090] Based on the above-mentioned Examples 1 and Comparative Examples 4-6 of this application and the data in Tables 1-2, it can be seen that for the adhesive in this application, a three-step degreasing method is preferable. At the same time, when the degreasing temperature of the first step is controlled at 560-780℃, the degreasing temperature of the second step is controlled at 880-950℃, and the degreasing temperature of the third step is controlled at 1200-1300℃, the removal rate of organic matter in the molybdenum end cap can be effectively improved, the purity of the molybdenum end cap can be improved, and the welding stability of the molybdenum end cap can be promoted.

[0091] Based on the above-mentioned Examples 1 and 3-4 of this application and the data in Table 1-2, it can be seen that: compared with chain extension using dihydrazide terephthalate or ethylenediamine, the isocyanate-terminated polyurethane prepolymer obtained by chain extension using dihydrazide succinate, when mixed with polyethylene glycol monomethyl ether glycidyl ether and polyvinyl butyral to prepare an adhesive, can further improve the dispersibility of the adhesive, further improve the particle size distribution stability of the obtained molybdenum particles, and further promote the improvement of the molding stability of the molybdenum end cap.

[0092] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a molybdenum end cap, characterized in that: Includes the following steps: Molybdenum powder, binder, and solvent are mixed evenly in a weight ratio of (45-55):(15-20):(25-30), granulated, and the solvent is removed to obtain molybdenum particles. The binder includes isocyanate-terminated polyurethane prepolymer, polyethylene glycol monomethyl ether glycidyl ether, polyvinyl butyral, and diluent. The weight ratio of isocyanate-terminated polyurethane prepolymer, polyethylene glycol monomethyl ether glycidyl ether, polyvinyl butyral, and diluent is (20-30):(8-12):(35-40):

100. The molybdenum particles are pressed into shape to obtain a pre-degreasing molybdenum end cap; the pre-degreasing molybdenum end cap is then degreased, the degreasing including a first degreasing, a second degreasing, and a third degreasing step. The first degreasing temperature is 560-780℃ and the time is 15-30s; the second degreasing temperature is 880-950℃ and the time is 15-30s; the third degreasing temperature is 1200-1300℃ and the time is 15-30s. The isocyanate-terminated polyurethane prepolymer comprises raw material components polyether diol, diisocyanate, succinic dihydrazide, catalyst, and viscosity reducer, wherein the weight ratio of polyether diol, diisocyanate, succinic dihydrazide, catalyst, and viscosity reducer is (50-60):(35-40):(5.5-6.8):(0.001-0.005):20; The preparation method of the isocyanate-terminated polyurethane prepolymer is as follows: heat the polyether diol to 50-55℃, then add diisocyanate, succinic dihydrazide and catalyst, stir evenly, then heat to 75-85℃ and react for 3-4 hours, then add viscosity reducer and stir evenly to obtain isocyanate-terminated polyurethane prepolymer.

2. The method for preparing a molybdenum end cap according to claim 1, characterized in that: The polyether diol is at least one of polypropylene glycol and polytetrahydrofuran diol.

3. The method for preparing a molybdenum end cap according to claim 1, characterized in that: The molecular weight range of the polyether diol is 1000-2000.

4. The method for preparing a molybdenum end cap according to claim 1, characterized in that: The diisocyanate is selected from aliphatic diisocyanates.

5. The method for preparing a molybdenum end cap according to claim 1, characterized in that: The viscosity reducer is selected from at least one of ethanol, acetone, and water.

6. A method for preparing a molybdenum end cap according to any one of claims 1-5, characterized in that: The adhesive is prepared as follows: Polyvinyl butyral is dissolved in a diluent, and then polyethylene glycol monomethyl ether glycidyl ether and isocyanate-terminated polyurethane prepolymer are added and stirred evenly to obtain the adhesive.

7. A method for preparing a molybdenum end cap according to any one of claims 1-5, characterized in that: The solvent used is an ethanol solution with a mass concentration of 10%-20%.

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