Y2Ti2O7 pyrochlore self-propagating high-temperature synthesis and densification method

A self-propagating high-temperature, densification technology, applied in chemical instruments and methods, inorganic chemistry, titanium compounds, etc., can solve the problems of long synthesis cycle, complex synthesis process, unfavorable large-scale promotion of pyrochlore solidification process, etc. High density, high product purity, long-term safety effect

Inactive Publication Date: 2015-04-22
SOUTHWEAT UNIV OF SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

These synthesis processes are relatively complicated and the synthesis cycle is long, which is not conducive to the large-scale promotion of pyrochlore solidification process

Method used

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  • Y2Ti2O7 pyrochlore self-propagating high-temperature synthesis and densification method
  • Y2Ti2O7 pyrochlore self-propagating high-temperature synthesis and densification method
  • Y2Ti2O7 pyrochlore self-propagating high-temperature synthesis and densification method

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] a Y 2 Ti 2 o 7 The self-propagating high-temperature synthesis and densification method of pyrochlore comprises the following steps:

[0046] (1) Use CuO powder as the oxidant and Ti powder as the reducing agent, and mix according to the reaction equation:

[0047] 6CuO+2Y 2 o 3 +3Ti+TiO 2 =2Y 2 Ti 2 o 7 +6Cu

[0048] The molar ratio of each reactant is CuO:Y 2 o 3 :Ti:TiO 2 =6:2:3:1, according to the respective molecular weight and content, the mass percentage of the corresponding reactant is: CuO: 41.2%, Y 2 o 3 : 39.0%, Ti: 12.9%, TiO 2 : 6.9%.

[0049] (2) Dry grind the weighed raw materials for 20 minutes to mix them evenly, pass the mixed materials through a 100-mesh sieve, take 20g of fully ground raw materials, put them into a Φ25mm steel mold, and cold press them under 20MPa pressure to obtain a diameter A cylindrical blank with a thickness of 25mm and a thickness of about 19mm.

[0050] (3) Put the prepared rough billet into the self-propagati...

Embodiment 2

[0053] a Y 2 Ti 2 o 7 The self-propagating high-temperature synthesis and densification method of pyrochlore comprises the following steps:

[0054] (1) Use CuO powder as the oxidizing agent and Ti powder as the reducing agent, and mix according to the reaction equation:

[0055] 2CuO+Y 2 o 3 +Ti+TiO 2 =Y 2 Ti 2 o 7 +2Cu

[0056] The molar ratio of each reactant is CuO:Y 2 o 3 :Ti:TiO 2 =2:1:1:1, according to the respective molecular weight and content, the corresponding mass percentage is: CuO: 31.0%, Y 2 o 3 : 44.0%, Ti: 9.4%, TiO 2 : 15.6%.

[0057] (2) Dry grind the weighed raw materials for 15 minutes to mix them evenly, pass the mixed materials through a 100-mesh sieve, take 25g of fully ground raw materials, put them into a Φ30mm steel mold, and cold press them under a pressure of 40MPa to obtain a diameter A cylindrical blank with a diameter of 40mm and a thickness of about 15mm.

[0058] (3) Put the prepared rough billet into the self-propagating quas...

Embodiment 3

[0061] a Y 2 Ti 2 o 7 The self-propagating high-temperature synthesis and densification method of pyrochlore comprises the following steps:

[0062] a. Ingredients: according to CuO:Y 2 o 3 :Ti:TiO 2 = 6:2:3:1 molar ratio (preferably the purity is higher than 99%, the particle size is less than 200 mesh) CuO, Y 2 o 3 , Ti, TiO 2 powder as raw material;

[0063] b. Abrasives: dry ball mill the above components for 10 minutes, mix them evenly, and pass through 100 sieves to obtain a mixture;

[0064] c. Rough billet compression molding: take 10g of the mixture and put it into a stainless steel mold (cylindrical mold of Φ20mm), and press the mixture into a cylindrical blank 2 with a diameter of 20mm by using a pressure of 10MPa;

[0065] d.Y 2 Ti 2 o 7 Self-propagating high-temperature synthesis and densification of pyrochlore blocks:

[0066] A self-propagating quasi-isostatic pressing device is adopted. The composition of the device includes an ignition tungsten w...

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Abstract

The invention discloses a Y2Ti2O7 pyrochlore self-propagating high-temperature synthesis and densification method. The method is characterized in that CuO, Y2O3, Ti and TiO2 powders are adopted as raw materials and are blended according to a certain molar ratio; the mixture is fully ground and well mixed, and is sieved; the mixed material is added into a stainless steel mold, and is pressed into a cylindrical blank; the blank is placed into a self-propagating quasi-isostatic pressing device; the blank is ignited with an ignition tungsten wire; within 5-30s after combustion is finished, a pressure of 50-200MPa is applied by a hydraulic machine and is maintained for 20-100s, such that a Y2Ti2O7 pyrochlore block is obtained. The method has the advantages of high synthesis speed, short production period, high reaction temperature, low energy consumption, controllable synthesis product phase, high product purity, high product density, simple process, and the like. The prepared Y2Ti2O7 pyrochlore is especially suitable for high-level radioactive nuclear waste long-term safe solidification treatment and disposal.

Description

technical field [0001] The invention belongs to the preparation of artificial rocks mainly used for the solidification treatment of radioactive waste, and relates to a Y 2 Ti 2 o 7 Self-propagating high-temperature synthesis and densification method of pyrochlore, Y prepared by the present invention 2 Ti 2 o 7 Pyrochlore is especially suitable for long-term safe solidification and disposal of high-level radioactive nuclear waste. Background technique [0002] High-level radioactive waste (HLW for short) is the focus and difficulty of radioactive waste treatment at home and abroad. Pyrochlore can fix the long-lived actinide nuclide atoms in HLW in its lattice structure, thereby greatly improving the stability of the solidified body And long-term security, it is an ideal HLW curing medium. Self-propagating high-temperature synthesis (SHS for short) is an important new technology for material preparation. It uses the exothermic heat of the chemical reaction to maintain th...

Claims

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Application Information

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IPC IPC(8): C01G23/00
CPCC01G23/003C01P2002/72
Inventor 张魁宝文冠军李玉香滕元成
Owner SOUTHWEAT UNIV OF SCI & TECH
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