A kind of freeze-drying preparation method of second-phase particle dispersed molybdenum composite powder

A technology for compounding powders and granules, applied in the field of powder preparation engineering, can solve the problems of hard agglomeration of crystal grains, high hydrothermal temperature, poor doping uniformity, etc., and achieve the effect of small agglomeration, easy agglomeration, and improved particle agglomeration

Active Publication Date: 2022-06-07
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Ball milling cannot guarantee the purity, the doping uniformity is also poor, and the size, shape, and distribution of the grains cannot be precisely regulated; other preparation methods will lead to uneven grain structure, large grains, and hard agglomeration of grains Serious, and the sol-gel method needs to use expensive alcohol, the reaction time of the hydrothermal synthesis method is long, and the hydrothermal temperature is high, all of which need to consume a lot of energy

Method used

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  • A kind of freeze-drying preparation method of second-phase particle dispersed molybdenum composite powder
  • A kind of freeze-drying preparation method of second-phase particle dispersed molybdenum composite powder
  • A kind of freeze-drying preparation method of second-phase particle dispersed molybdenum composite powder

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] (1) 5g of ammonium molybdate tetrahydrate and 0.05g of yttrium nitrate hexahydrate were dissolved in 50mL of deionized water, then 0.25g of PVPk-12 was dissolved in it, and finally added to 100ml with deionized water, and ultrasonically treated (ultrasonic treatment) The power is 50W, and the ultrasonic time is 2h) to fully dissolve and disperse to obtain a mixed solution.

[0026] (2) Then pour the mixture into liquid nitrogen to pre-freeze the mixture.

[0027] (3) After the temperature of the freeze dryer is lowered to the freezing temperature of -60°C and stabilized, put the pre-frozen watch glass into the freeze dryer, turn on the vacuum pump and keep the vacuum below 50Pa, and freeze-dry for 36 hours.

[0028] (4) The lyophilized powder was calcined in air at 450°C for 1.5 h to obtain composite oxide powder.

[0029] (5) The composite oxide powder is subjected to two-step reduction in a hydrogen stream (600° C. for 1.5 h, and 750° C. for 1.5 h) to obtain a compos...

Embodiment 2

[0031] (1) Dissolve 1 g of ammonium molybdate tetrahydrate and 0.001 g of lanthanum nitrate hexahydrate in 50 mL of deionized water, then dissolve 0.02 g of PEG-6000 in it, and finally add it to 100 mL with deionized water, and use ultrasonic treatment (ultrasonic treatment) The power is 150W, and the ultrasonic time is 0.1h) to be fully dissolved and dispersed to obtain a mixed solution.

[0032] (2) Then pour the mixture into dry ice to pre-freeze the mixture.

[0033] (3) After the temperature of the freeze dryer is lowered to the freezing temperature of -80°C and stabilized, put the pre-frozen watch glass into the freeze dryer, turn on the vacuum pump and keep the vacuum below 50Pa, and freeze-dry for 5 hours.

[0034] (4) The lyophilized powder was calcined in air at 450° C. for 0.5 h to obtain composite oxide powder.

[0035](5) The composite oxide powder is subjected to two-step reduction in a hydrogen stream (550° C. for 0.5 h, and 700° C. for 0.5 h) to obtain a compo...

Embodiment 3

[0037] (1) Dissolve 20 g of ammonium molybdate heptahydrate, 0.5 g of yttrium nitrate hexahydrate, and 0.5 g of zirconium nitrate pentahydrate in 50 mL of deionized water, then dissolve 1 g of PVP K12 and 1 g of PEG-6000 in it, and finally use deionized water. Water was added to 100ml, fully dissolved and dispersed by ultrasonic treatment (ultrasonic treatment power was 250W, ultrasonic time 1.5h) to obtain a mixed solution.

[0038] (2) Then pour the mixture into liquid nitrogen to pre-freeze the mixture.

[0039] (3) After the temperature of the freeze dryer is lowered to the freezing temperature of -60°C and stabilized, put the pre-frozen watch glass into the freeze dryer, turn on the vacuum pump and keep the vacuum below 50Pa, and freeze-dry for 48h.

[0040] (4) The lyophilized powder was calcined in air at 450° C. for 2 h to obtain composite oxide powder.

[0041] (5) The composite oxide powder is subjected to two-step reduction in a hydrogen stream (700° C. for 3 hours...

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Abstract

The present invention proposes a freeze-drying preparation method of second-phase particle-dispersed molybdenum composite powder, adding rare earth nitrate or carbide particles together with molybdate and surfactant into deionized water and ultrasonic treatment to prepare solution or suspension Turbid liquid: pre-freeze the solution or suspension, such as pre-freezing with liquid nitrogen or dry ice, or pre-freezing in a low-temperature environment such as a refrigerator -60--10°C for 4-12 hours, and then freeze-drying, that is, after pre-freezing Put the solution or suspension into the freeze-drying machine whose freeze-drying temperature reaches the preset temperature -80--20°C and is stable, and turn on the vacuum pump to maintain the vacuum degree below 50Pa, freeze-dry for 5-48h; freeze-dry the precursor Calcination of bulk powder, followed by two-step reduction in a reducing atmosphere to finally obtain ultrafine second-phase particle-dispersed molybdenum composite powder. The invention not only can realize the preparation of ultrafine nanometer powder, but also is very suitable for the preparation of a large amount of composite powder in a single batch.

Description

technical field [0001] The invention provides a technology for the freeze-drying preparation method of second-phase particle-dispersed molybdenum composite powder, which belongs to the technical field of powder preparation engineering. Background technique [0002] Molybdenum (Mo) and its alloys have the characteristics of high melting point, high strength, good thermal conductivity and low thermal expansion coefficient, and are widely used in metallurgy, machinery, chemical industry, aerospace, military and other industries. However, molybdenum has a typical body-centered cubic structure with few sliding systems, so it is usually accompanied by brittleness and large deformation processing difficulties. In addition, low recrystallization temperature, high ductile-brittle transition temperature, and low strength limit its application. [0003] The second-phase particle dispersion strengthening and grain refinement are the focus of researchers in the field of molybdenum-based...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22F9/22
CPCY02E60/36
Inventor 马宗青扈伟强董智余黎明刘永长
Owner TIANJIN UNIV
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