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Freeze-drying preparation method of second-phase particle dispersion molybdenum composite powder

A composite powder and granule technology, which is applied in the field of powder preparation engineering, can solve the problems of hard agglomeration of crystal grains, high hydrothermal temperature, and poor doping uniformity, and achieve the effect of small agglomeration, easy agglomeration, and improved particle agglomeration

Active Publication Date: 2021-04-16
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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  • Freeze-drying preparation method of second-phase particle dispersion molybdenum composite powder
  • Freeze-drying preparation method of second-phase particle dispersion molybdenum composite powder
  • Freeze-drying preparation method of second-phase particle dispersion molybdenum composite powder

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025](1) 5 g of four hydromide-molymmonium molybdate and 0.05 nitrate hexahydrate were dissolved in 50 ml deionized water, and 0.25 g of PVPK-12 was dissolved in it, and finally used to add to 100 ml, ultrasonic treatment (ultrasound treatment) The power is 50W, ultrasonic time 2H) is well dissolved, dispersed, and the mixture is obtained.

[0026](2) The mixture was then poured into liquid nitrogen and pre-free mixed liquid.

[0027](3) When the freeze-dried machine temperature reaches the freezing temperature -60 ° C and stabilizes, the pre-free surface vessel is placed in a cryogenic dryer, and the vacuum pump is opened and the vacuum is maintained or less, freeze drying 36h.

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

[0029](5) The composite oxide powder was subjected to two-step reduction in a hydrogen gas stream (600 ° C holding 1.5 h, 750 ° C holding 1.5 h) to obtain a composite powder. Finally, the precursor powder is coole...

Embodiment 2

[0031](1) 1 g of tetrahydrate and 0.001 g of nitrate hexahydrate is dissolved in 50 ml deionized water, and 0.02 g PEG-6000 is dissolved therein, and finally with deionized water to 100 ml, ultrasonic treatment (ultrasound treatment) The power is 150W, ultrasonic time is 0.1h) is well dissolved, dispersed, and the mixture is obtained.

[0032](2) The mixture was then poured into dry ice, pre-free mixed.

[0033](3) When the freeze-up machine temperature reaches the freezing temperature -80 ° C and stabilizes, the pre-free surface vessel is placed in a freeze dryer, and the vacuum pump is opened and the vacuum degree is 50 Pa or less, and dried for 5 h.

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

[0035](5) The composite oxide powder was subjected to two-step reduction in a hydrogen gas stream (550 ° C holding 0.5 h, 700 ° C holding 0.5h) to obtain a composite powder. Finally, the precursor powder is cooled to room temperature in a hy...

Embodiment 3

[0037](1) 20 g of 20 g of aqua-molybdomide, 0.5 g of nitrate hexahydrate, 0.5 g of zirconium nitrate penthyme hydrate is dissolved in 50 ml of deionized water, and 1 g of PVP K12 and 1GPEG-6000 is soluble in it, and finally use deion. Water was added to 100 mL, and the mixture was fully dissolved and dispersed by ultrasonic treatment (ultrasonic treatment power of 250W, ultrasonic time 1.5H).

[0038](2) The mixture was then poured into liquid nitrogen and pre-free mixed liquid.

[0039](3) When the temperature of the lyophilized machine reaches the freezing temperature -60 ° C and stabilizes, the pre-free surface vessel is placed in a cryogenic dryer, and the vacuum pump is opened and the vacuum degree is 50 Pa or less, freeze drying 48 h.

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

[0041](5) Two-step reduction in a hydrogen gas stream (700 ° C insulation for 3 h, 800 ° C holding 2H) was obtained. Finally, the precursor powder...

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Abstract

The invention provides a freeze-drying preparation method of second-phase particle dispersion molybdenum composite powder. The method comprises the following steps that rare-earth nitrate or carbide particles, molybdate and a surfactant are added to deionized water together and are subjected to ultrasonic treatment, and a solution or turbid liquid is prepared; pre-freezing is performed on the solution or the turbid liquid by the aid of liquid nitrogen or dry ice, or pre-freezing is performed for 4-12 hours in a low-temperature environment such as a refrigerator and the like at subzero 60-subzero 10 DEG C, then freeze-drying is performed, that is, the pre-frozen solution or turbid liquid is placed into a stable freeze-drying machine of which the freeze-drying temperature reaches a preset temperature of subzero 80-subzero 20 DEG C, a vacuum pump is started, the vacuum degree is kept below 50 Pa, and freeze-drying is performed for 5-48 hours; and the freeze-dried precursor powder is calcined, and then two-step reduction is performed in a reducing atmosphere, and the superfine second-phase particle dispersed molybdenum composite powder is obtained finally. According to the method, preparation of the superfine nano powder can be realized, and meanwhile, the method is very suitable for single-batch large-scale preparation of the composite powder.

Description

Technical field[0001]The present invention proposes a technique for a cryogenic drying preparation method of a second phase particles to dissipate molybdenum composite powder, belonging to the field of preparation engineering.Background technique[0002]Molybdenum (Mo) and its alloys have high melting point, high strength, good thermal conductivity, low thermal expansion coefficient, widely used in metallurgical, mechanical, chemical, aerospace, military and other industries. However, molybdenum has a typical intimate cubic structure with few sliding systems, and therefore is usually accompanied by brittle and large deformation. In addition, low recrystallization temperature, high roughness transition temperature and low intensity limit their application.[0003]The second phase particles dispersion strengthening and grain refinement are the focus of researchers of molybdenum-based alloy fields. Second phase particles such as carbides (Zrc, Tac, Tic, etc.) and rare earth oxides (LA2O3Y2...

Claims

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Application Information

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Patent Type & Authority Applications(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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