阅读说明：本技术 一种以稀土元素-铁氧化物制备胚体的方法 (Method for preparing embryo body by using rare earth element-iron oxide ) 是由 李笑天 于 2020-07-23 设计创作，主要内容包括：本发明提出了一种以稀土元素-铁氧化物制备胚体的方法,涉及陶瓷材料合成技术领域。该方法将三氧化二铁、稀土元素氧化物和胚体还原剂混合,得到混合物,将混合物压制成预胚体,再将预胚体置于烧结装置中烧结,得到胚体；烧结装置内放置有还原剂或除氧剂,胚体还原剂为铁粉或氧化亚铁；还原剂或除氧剂的还原活性高于胚体还原剂的活性。本发明的优点在于,可以有效将环境的残余氧化性降低到刚好不影响原料的程度,使稀土元素-铁氧化物胚体中的活性成分准确达到目标氧化价,同时易于放大生产,也便于制备各种大尺寸或者复杂形状的陶瓷胚体。(The invention provides a method for preparing a blank by using rare earth element-iron oxide, and relates to the technical field of ceramic material synthesis. Mixing ferric oxide, rare earth element oxide and a blank reducing agent to obtain a mixture, pressing the mixture into a pre-blank, and sintering the pre-blank in a sintering device to obtain a blank; a reducing agent or a deoxidant is placed in the sintering device, and the embryo reducing agent is iron powder or ferrous oxide; the reducing activity of the reducing agent or oxygen scavenger is higher than the activity of the embryo reducing agent. The method has the advantages that the residual oxidability of the environment can be effectively reduced to the extent of not influencing the raw materials, so that the active ingredients in the rare earth element-iron oxide embryo body accurately reach the target oxidation value, and meanwhile, the method is easy for scale-up production and is convenient for preparing various ceramic embryo bodies with large sizes or complex shapes.)

1. A method for preparing a blank body by using rare earth element-iron oxide is characterized by comprising the following steps: mixing ferric oxide, rare earth element oxide and a blank reducing agent to obtain a mixture, pressing the mixture into a pre-blank, and sintering the pre-blank in a sintering device to obtain a blank; a reducing agent or a deoxidant is placed in the sintering device, and the embryo reducing agent is iron powder or ferrous oxide; the reducing activity of the reducing agent or the oxygen scavenger is higher than the activity of the embryo reducing agent.

2. The method of claim 1, wherein the rare earth element oxide comprises one or more of Yb, Y, and Lu oxides.

3. The method of claim 1, wherein the molar number ratio of the iron sesquioxide, the rare earth element oxide and the iron powder is (4-6): (2-4): (1-3).

4. The method of claim 3, wherein the molar number ratio of the iron trioxide, the rare earth element oxide, and the iron powder is 5:3: 2.

5. The method of claim 1, wherein the molar quantity ratio of the ferric oxide, the rare earth element oxide and the ferrous oxide is (0.5-1.5): (1-3).

6. The method of claim 5, wherein the molar number ratio of ferric oxide, rare earth oxide, and ferrous oxide is 1:1: 2.

7. The method according to any one of claims 1 to 6, wherein the sintering temperature is 1200 to 1500 ℃ and the sintering time is 15 to 26 hours.

8. The method according to claim 7, wherein the sintering temperature is 1300 ℃ and the sintering time is 24 h.

9. The method of any one of claims 1-6, wherein the iron powder has a particle size below 325 mesh.

10. The method according to any one of claims 1 to 6, wherein the ferric oxide, the rare earth element oxide and the embryo reducing agent are mixed by milling with one or both of isopropyl alcohol and acetone.

Technical Field

The invention relates to the technical field of ceramic material synthesis, in particular to a method for preparing a blank by using rare earth element-iron oxide.

Background

Rare earth-iron oxides are ceramic-state substances with reversible redox activity. In the process of preparing the blank by using the ceramic material, high temperature is usually used, and in order to ensure the effect of the blank, the active ingredients in the product need to accurately reach the target oxidation number under the high temperature condition, but the requirement needs to be harsh. If no special means exists, the error of the sealing degree of the reaction container and the purity of the protective gas commonly used in the prior art makes active ingredients in the product difficult to meet the requirement of target oxidation number.

Currently, green bodies are prepared from ceramic-state substances by using several methods:

1. and (2) wet method: and adding a coordination polymerization agent into the salt solution of iron and the corresponding rare earth element, evaporating the solution to dryness and calcining to obtain mixed powder. The method is suitable for the preparation of products which have no redox activity of raw materials and do not need to be molded from powder, finished products can be directly obtained, and the subsequent heating treatment similar to that of a solid phase method is still needed, but the method is basically eliminated due to complexity and no gain effect.

2. Solid-phase reaction method: the method directly uses powders of ferric oxide, iron powder and rare earth oxide to be mixed, pressed and molded and then carries out heating reaction to prepare a blank. Specifically, the method is classified into a reducing atmosphere method and a closed vessel method. The reducing atmosphere method is that besides inert gas, reducing gas with certain concentration is added into the reaction environment to make the iron component in the product reach the required oxidation value. The reducing agent in this process is typically hydrogen or carbon monoxide at a concentration of no more than 5%; the optimum exact value of this concentration has been theoretically determined by phase diagrams, but few attempts have actually been made to achieve the exact value. In addition, it has been reported that the target oxidation number of the active ingredient can be achieved by merely reducing the oxygen concentration in the atmosphere to a sufficiently low concentration without using a reducing agent, but the sufficiently low concentration indicated in the study is a level that is difficult to achieve in actual production (10. about.^-14Pa) is added. The method has the defects that the reducing strength of the reaction environment is difficult to accurately control, and further, a high-purity product is difficult to stably obtain. The closed vessel method is a method of preparing an embryo by heating and reacting trivalent iron, reducing iron and rare earth oxide in a stoichiometric ratio in a closed vessel filled with an inert gas, such as a sealed tube. The method has good effect of maintaining the purity of the product, but the sealing of the reaction vessel requires relatively complicated operation and is difficult to produce in large scale.

Therefore, if a method could be developed that would overcome the aforementioned drawbacks, it would be advantageous to have a wide application of rare earth-iron oxides in the preparation of ceramic green bodies.

Disclosure of Invention

The invention aims to provide a method for preparing a blank by using rare earth element-iron oxide, which can ensure that active ingredients in the blank of the rare earth element-iron oxide accurately reach a target oxidation number.

The technical problem to be solved by the invention is realized by adopting the following technical scheme.

The embodiment of the application provides a method for preparing a blank by using rare earth element-iron oxide, which comprises the following steps: uniformly mixing ferric oxide, rare earth element oxide and an embryo reducing agent to obtain a mixture, pressing the mixture into a pre-embryo, and sintering the pre-embryo in a sintering device to obtain an embryo; a reducing agent or a deoxidant is placed in the sintering device, and the embryo reducing agent is iron powder or ferrous oxide; the reducing activity of the reducing agent or oxygen scavenger is higher than the activity of the embryo reducing agent.

In summary, compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

the method for preparing the blank body by the rare earth element-iron oxide is characterized in that a reducing agent or an oxygen scavenger with reduction activity slightly higher than that of a blank body reducing agent is added into sintering equipment for protecting raw materials, so that the residual oxidability of the environment can be effectively reduced to the extent of not influencing the raw materials, the active ingredients in the rare earth element-iron oxide blank body can accurately reach the target oxidation number, the problem that the oxygen concentration in the environment needs to be reduced in the traditional technology so as to protect the raw materials but the oxygen concentration cannot be reduced to the required level in the prior art is solved, meanwhile, the method is easy to produce in an enlarged mode, and is also convenient for preparing various ceramic blank bodies with large sizes or complex shapes.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The embodiment of the application provides a method for a rare earth element-iron oxide embryo body, which comprises the following steps: uniformly mixing ferric oxide, rare earth element oxide and an embryo reducing agent to obtain a mixture, pressing the mixture into a pre-embryo, and sintering the pre-embryo in a sintering device to obtain an embryo; a reducing agent or a deoxidant is placed in the sintering device, and the embryo reducing agent is iron powder or ferrous oxide; the reducing activity of the reducing agent or oxygen scavenger is higher than the activity of the embryo reducing agent. By adding a reducing agent or a deoxidant with the reduction activity slightly higher than that of the embryo reducing agent into the sintering equipment for protecting the raw materials, the residual oxidability of the environment can be effectively reduced to the degree that the raw materials are not influenced, so that the active ingredients in the rare earth element-iron oxide embryo accurately reach the target oxidation number, and the problem that the oxygen concentration in the environment needs to be reduced in the traditional technology so as to protect the raw materials but the oxygen concentration cannot be reduced to the required level in the prior art is solved.

In some embodiments of the invention, the rare earth oxide in the above method comprises one or more of Yb, Y and Lu oxides. Besides the Yb, Y and Lu oxides, other rare earth element oxides with properties similar to those of the Yb, Y and Lu can also be used.

In some embodiments of the present invention, the molar ratio of the iron sesquioxide, the rare earth element oxide and the iron powder in the above method is (4-6): (2-4): 1-3). The active substances in the embryo prepared by the raw materials with the proportion can reach the target oxidation number and have higher purity.

In some embodiments of the present invention, the molar quantity ratio of ferric oxide, rare earth element oxide and iron powder in the above method is 5:3: 2. The percentage of active material in the embryo prepared from the raw materials in the ratio reaching the target oxidation number is the highest.

In some embodiments of the present invention, the molar quantity ratio of the ferric oxide, the rare earth element oxide and the ferrous oxide in the above method is (0.5-1.5): 1-3). The active substances in the embryo prepared by the raw materials with the proportion can reach the target oxidation number and have higher purity.

In some embodiments of the present invention, the molar quantity ratio of ferric oxide, rare earth oxide and ferrous oxide in the above process is 1:1: 2. The percentage of active material in the embryo prepared from the raw materials in the ratio reaching the target oxidation number is the highest.

In some embodiments of the present invention, the sintering temperature in the above method is 1200-1500 ℃, and the sintering time is 15-26 h. Sintering temperatures and times within this range give green bodies of comparable quality.

In some embodiments of the present invention, the sintering temperature in the above method is 1300 ℃, and the sintering time is 24 h.

In some embodiments of the present invention, the iron powder has a particle size of less than 325 mesh in the above-described method. The granularity and the iron powder smaller than the granularity can ensure that the raw materials are fully reduced to reach the target oxidation number.

In some embodiments of the present invention, the ferric oxide, the rare earth element oxide and the embryo reducing agent are mixed by grinding, and the liquid used for grinding is one or both of isopropyl alcohol and acetone. Instead of grinding the raw materials using isopropanol or acetone in a common mortar, the raw materials may be mixed by feeding them into a ball mill.

The features and properties of the present invention are described in further detail below with reference to examples.