阅读说明：本技术 一种微掺镧高温钼丝的制备方法 (Preparation method of lanthanum-micro-doped high-temperature molybdenum wire ) 是由 陈耿辉 李文岭 赵长庆 刘丽丽 李志伟 付天丰 张海华 于 2019-10-11 设计创作，主要内容包括：本发明属于高温钼丝的制备技术领域,尤其为一种微掺镧高温钼丝的制备方法,包括以下步骤：S1：将钼酸铵和稀土硝酸镧的混合溶液按稀土氧化物0.3-0.5％La<Sub>2</Sub>O<Sub>3</Sub>的比例进行喷雾掺杂得到混合物A；S2：将S1中所制得的混合物A进行加热分解、两段还原工序制得复合一定要求的均匀掺杂的稀土氧化镧的钼粉体；S3：将S2中所制得的均匀掺杂的稀土氧化镧的钼粉体依次经过筛、混粉、冷等静压、预烧和中频烧结工序制得坯条。本发明设计合理,经济节能,通过对微掺镧高温钼丝的工艺和设备进行调整和改进,可获得材质均匀、成材率高的微掺镧高温钼丝,有效地提高了微掺镧高温钼丝的高温使用性能。(The invention belongs to the technical field of preparation of high-temperature molybdenum wires, and particularly relates to a preparation method of a lanthanum-micro-doped high-temperature molybdenum wire, which comprises the following steps: s1: mixing the mixed solution of ammonium molybdate and rare earth lanthanum nitrate according to the proportion of 0.3-0.5 percent of La of rare earth oxide 2 O 3 The mixture A is obtained by spraying and doping according to the proportion; s2: carrying out heating decomposition and two-stage reduction processes on the mixture A prepared in the step S1 to prepare molybdenum powder body compounded with uniformly doped rare earth lanthanum oxide with certain requirements; s3: and (3) sequentially carrying out sieving, powder mixing, cold isostatic pressing, presintering and intermediate frequency sintering on the molybdenum powder of the uniformly doped rare earth lanthanum oxide prepared in the step (S2) to prepare a billet. The invention has reasonable design, is economical and energy-saving, can obtain the micro lanthanum-doped high-temperature molybdenum wire with uniform material and high yield by adjusting and improving the process and the equipment of the micro lanthanum-doped high-temperature molybdenum wire, and effectively improvesThe high-temperature service performance of the lanthanum-micro-doped high-temperature molybdenum wire is improved.)

1. A preparation method of a lanthanum micro-doped high-temperature molybdenum wire is characterized by comprising the following steps: the method comprises the following steps:

s1: mixing the mixed solution of ammonium molybdate and rare earth lanthanum nitrate according to the proportion of 0.3-0.5 percent of La of rare earth oxide₂O₃The mixture A is obtained by spraying and doping according to the proportion;

s2: carrying out heating decomposition and two-stage reduction processes on the mixture A prepared in the step S1 to prepare molybdenum powder body compounded with uniformly doped rare earth lanthanum oxide with certain requirements;

s3: sequentially carrying out sieving, powder mixing, cold isostatic pressing, presintering and intermediate frequency sintering on the molybdenum powder of the uniformly doped rare earth lanthanum oxide prepared in the S2 to prepare billet;

s4: the billet prepared in the S3 is subjected to multi-stage rotary swaging processing, recrystallization annealing, wire drawing and wire sintering to prepare a finished product of the lanthanum-micro-doped high-temperature molybdenum wire;

s5: and (4) carrying out finished product inspection on the finished product of the lanthanum-micro-doped high-temperature molybdenum wire prepared in the S4.

2. The method for preparing the lanthanum-micro-doped high-temperature molybdenum wire according to claim 1, wherein the method comprises the following steps: in the step S1, the rare earth lanthanum nitrate is placed in deionized water to be dissolved to obtain a rare earth lanthanum nitrate solution; placing ammonium molybdate in a spray doping dryer; the rare earth lanthanum nitrate solution was added to ammonium molybdate in the form of a spray for uniform doping, followed immediately by vacuum drying and mixing.

3. The method for preparing the lanthanum-micro-doped high-temperature molybdenum wire according to claim 1, wherein the method comprises the following steps: in the S2, after the mixture A prepared in the S1 is heated and decomposed, a two-stage reduction process is carried out in a hydrogen purification mode, and the dew point of hydrogen is less than-40 ℃ and the oxygen content is less than 10ppm in the process.

4. The method for preparing the lanthanum-micro-doped high-temperature molybdenum wire according to claim 1, wherein the method comprises the following steps: in the step S3, when the pre-sintering process is performed, long-time heat preservation is performed at the heat preservation point of each of the low and medium temperature stages, so as to increase the densification degree of the billet, reduce the volatilization of the rare earth at the high temperature stage, and fully ensure the content of the rare earth element lanthanum.

5. The method for preparing the lanthanum-micro-doped high-temperature molybdenum wire according to claim 1, wherein the method comprises the following steps: and in the step S4, the billet is subjected to rotary swaging processing, recrystallization annealing, wire drawing and wire burning by adopting a mechanical rotary swaging machine and an automatic string beating machine set to obtain the finished product of the lanthanum-micro-doped high-temperature molybdenum wire.

Technical Field

The invention relates to the technical field of preparation of high-temperature molybdenum wires, in particular to a preparation method of a lanthanum-micro-doped high-temperature molybdenum wire.

Background

Molybdenum and molybdenum alloy wires have the advantages of high melting point, high-temperature strength, good electric and heat conducting properties, low expansion coefficient, good corrosion resistance, good chemical stability and the like, so the molybdenum and molybdenum alloy wires are widely applied to the electronic industry, the chemical industry, the metallurgical industry and the aerospace industry, are mainly used as electric light source bulbs, hot body supports, electronic tube grids, emitting tubes and secondary rectifier tube cathodes in the electric light source and electric vacuum industry, are mainly used for electric spark machining in the mechanical machining industry, are also excellent high-temperature materials, and are widely used as raw materials for manufacturing heating bodies of vacuum furnaces, atmosphere-protecting furnaces and high-temperature furnaces. The sprayed molybdenum wire is mainly used for finely spraying the surfaces of automobile wearing parts and mechanical wearing surfaces to enhance the wear resistance.

The pure molybdenum wire has low-temperature brittleness, mainly because the recrystallization temperature of the pure molybdenum is low (about 1100 ℃), the tissue structure is changed from a fibrous shape to an equiaxial shape at high temperature, the mechanical property is reduced, and oxygen and molybdenum are easy to generate oxides which are enriched in a grain boundary, the grain boundary strength is reduced, so the high-temperature property of the pure molybdenum is poor, brittle fracture is frequently generated during processing deformation, the pure molybdenum wire is easy to deform at high temperature, the service life is short, and the defects seriously restrict the application of the pure molybdenum wire in engineering.

The high-temp molybdenum wire with micro-doped lanthanum is a molybdenum alloy wire which still has stable performance at higher temp. and its recrystallization temp. is higher than that of pure molybdenum wire, and is about 1600 deg.C, and after recrystallization it can still retain a certain strength and plasticity, and is made up by doping molybdenum with a trace rare earth element, so that it is also called doped molybdenum. The research shows that: doping of rare earth oxide La in molybdenum₂O₃Can improve the microstructure of molybdenum, La is formed after the recrystallization of molybdenum at high temperature₂O₃The particles have the function of inhibiting the transformation of recrystallized grains to equiaxed grains, so that the recrystallized grains form a large and long swallowtail-shaped mutually-connected grain structure, and the La is used for preventing the transformation of the recrystallized grains to the equiaxed grains₂O₃The oxygen in the molybdenum is absorbed, the oxygen segregation in the grain boundary is slowed down, the grain boundary is strengthened, thereby improving the room temperature brittleness of the molybdenum and reducing the plastic-brittlenessThe transition temperature is greatly improved, so that the high-temperature performance of the La-Mo wire is greatly improved, but the production efficiency of the lanthanum-micro-doped high-temperature molybdenum wire is low due to the fact that the existing lanthanum-micro-doped high-temperature molybdenum wire is complicated in working procedure, and therefore the preparation method of the lanthanum-micro-doped high-temperature molybdenum wire is provided.

Disclosure of Invention

The invention aims to solve the defects in the prior art and provides a preparation method of a micro-lanthanum-doped high-temperature molybdenum wire.

In order to achieve the purpose, the invention adopts the following technical scheme: a preparation method of a lanthanum micro-doped high-temperature molybdenum wire comprises the following steps:

s1: mixing the mixed solution of ammonium molybdate and rare earth lanthanum nitrate according to the proportion of 0.3-0.5 percent of La of rare earth oxide₂O₃The mixture A is obtained by spraying and doping according to the proportion;

s2: carrying out heating decomposition and two-stage reduction processes on the mixture A prepared in the step S1 to prepare molybdenum powder body compounded with uniformly doped rare earth lanthanum oxide with certain requirements;

s3: sequentially carrying out sieving, powder mixing, cold isostatic pressing, presintering and intermediate frequency sintering on the molybdenum powder of the uniformly doped rare earth lanthanum oxide prepared in the S2 to prepare billet;

s4: the billet prepared in the S3 is subjected to multi-stage rotary swaging processing, recrystallization annealing, wire drawing and wire sintering to prepare a finished product of the lanthanum-micro-doped high-temperature molybdenum wire;

s5: and (4) carrying out finished product inspection on the finished product of the lanthanum-micro-doped high-temperature molybdenum wire prepared in the S4.

Preferably, in S1, the rare earth lanthanum nitrate is placed in deionized water to be dissolved to obtain a rare earth lanthanum nitrate solution; placing ammonium molybdate in a spray doping dryer; the rare earth lanthanum nitrate solution was added to ammonium molybdate in the form of a spray for uniform doping, followed immediately by vacuum drying and mixing.

Preferably, in S2, after the mixture A prepared in S1 is heated and decomposed, a two-stage reduction process is carried out in a hydrogen purification mode, and the dew point of hydrogen is less than-40 ℃ and the oxygen content is less than 10 ppm.

Preferably, in S3, when performing the pre-sintering process, long-time heat preservation is adopted at each of the heat preservation points in the low and medium temperature stages, so as to increase the densification degree of the billet, reduce the volatilization of the rare earth in the high temperature stage, and fully ensure the content of the rare earth element lanthanum.

Preferably, in S4, the mechanical hand rotary swaging machine and the automatic string beating machine set are used to perform the rotary swaging, recrystallization annealing, wire drawing and wire sintering processes on the billet to obtain the final product of the lanthanum-micro-doped high-temperature molybdenum wire.

Compared with the prior art, the invention has the beneficial effects that:

firstly, the recrystallization temperature of the molybdenum can be greatly increased;

second, La is generated during the reduction process₂O₃The particles have an embedding effect on Mo on the surface or the periphery of the metal Mo, so that the contact area of the molybdenum and the atmosphere is reduced, and the oxidation resistance of the molybdenum is enhanced;

third, La₂O₃Can refine crystal grains, improve the toughness and the bending strength of the molybdenum blank in a sintering state, and pass through La₂O₃The content is increased, the bending strength is improved, and the produced blank has good processing performance and high yield;

fourthly, the production process is simplified, thereby improving the production efficiency of the micro-lanthanum-doped high-temperature molybdenum wire.

The method has reasonable design, is economical and energy-saving, can obtain the micro lanthanum-doped high-temperature molybdenum wire with uniform material and high yield by adjusting and improving the process and the equipment of the micro lanthanum-doped high-temperature molybdenum wire, and effectively improves the high-temperature service performance of the micro lanthanum-doped high-temperature molybdenum wire.

Drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 is a control diagram of the process parameters of the present invention;

fig. 3 is a schematic diagram of a stringing device according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.