CN102701749A - Preparation method for cubic zirconia-beta phase silicon carbide complex phase high temperature resistance powder material - Google Patents

Abstract

The invention relates to a method for preparing a cubic zirconia-β-phase silicon carbide composite phase high-temperature-resistant powder material, and belongs to the technical field of high-temperature-resistant powder material preparation. It is characterized by using zircon, zircon sand or zirconium silicate as the main raw material, carbon black, coke, graphite, or activated carbon as the reducing agent, and magnesium oxide, calcium oxide, yttrium oxide or cerium oxide as additives. After the proportioned ingredients are mixed, the cubic zirconia-β phase silicon carbide composite phase high temperature resistant powder material is prepared through ball milling, drying, molding, carbothermal reduction and other processes. The preparation method of the cubic zirconia-β phase silicon carbide composite phase high temperature resistant powder material has many advantages such as short process flow, no pollution, low energy consumption and low cost.

Description

A preparation method of cubic zirconia-β phase silicon carbide composite phase high temperature resistant powder material

Technical field:

The invention discloses a method for preparing a cubic zirconia-β-phase silicon carbide composite phase high-temperature-resistant powder material, which belongs to the technical field of high-temperature-resistant powder material preparation.

Background technique:

Zirconia materials have excellent mechanical, thermal, electrical and optical properties, and are widely used in many fields such as high-temperature structural materials, dielectric materials, high-temperature optical devices for sensors, and fuel cells. Cubic phase zirconia has very excellent physical properties, including rare high melting point, high thermal conductivity, high elastic modulus, and can maintain high strength at high temperature, and also has good thermal shock resistance and moderate thermal expansion It is considered to be one of the most promising materials in the high temperature field in the future. Silicon carbide materials have excellent properties such as high hardness, high melting point, corrosion resistance, wear resistance, good thermal shock resistance, strong high temperature oxidation resistance, low thermal expansion coefficient, good chemical stability, and good thermal conductivity. , electronics, aerospace and building materials and other fields have been widely used.

The disadvantages of zirconia ceramic materials are low toughness, high cost, low reliability and low repeatability, which seriously affect the application range of zirconia ceramic materials. Therefore, only by improving the fracture toughness of ceramics, realizing the strengthening and toughening of materials, and improving their reliability and service life, can they truly become a widely used new material. β-phase silicon carbide has excellent thermal shock resistance and oxidation resistance, and fibrous β-phase silicon carbide is often used as the matrix phase of structural ceramics. Zirconia-silicon carbide composite materials combine the advantages of zirconia and silicon carbide materials, effectively improve the strength and toughness of zirconia ceramic materials, and have great development value and application prospects in high temperature resistant materials. Common zirconia-silicon carbide composite materials are obtained by mechanically mixing powder raw materials, and then forming, drying and high-temperature sintering processes to obtain high-performance composite ceramic materials. This mechanical mixing process is difficult to obtain uniform distribution and optimized particle gradation among different materials, and it is also easy to cause agglomeration and interlocking of fibrous silicon carbide materials, and both zirconia and silicon carbide materials are high energy consumption products. The industrial production process not only consumes a lot of energy, but also has a high degree of waste of resources, resulting in a high cost of zirconia-silicon carbide composite materials.

At present, the preparation methods of cubic zirconia powder at home and abroad mainly include hydrolysis method, precipitation method, hydrothermal method, sol-gel method, spray pyrolysis method, freeze-drying method and high-energy ball milling method, etc. The cubic zirconia powder synthesized by these preparation methods has defects such as easy agglomeration and low purity, and its process is complicated, high in cost, and high in energy consumption. Therefore, it is of great significance to realize low-cost preparation of cubic zirconia raw materials and energy saving and consumption reduction. .

The zirconia-silicon carbide composite powder material prepared by the carbon thermal reduction process of zircon, zircon sand or zirconium silicate can realize the synthesis of zirconia and silicon carbide materials in one step. The composite powder raw material can be used to prepare high-performance zirconia-beta phase silicon carbide composite materials. The zirconia material prepared by carbon thermal reduction of zircon mainly exists in the form of monoclinic phase, and the monoclinic zirconia material is accompanied by a volume change of about 7% during high-temperature sintering, which is easy to cause cracking of the product and lower the strength of the product. will be greatly reduced, and the impact of this defect on zirconia-based ceramic materials is fatal. Based on solving this fatal defect, the patent application of the present invention proposes to properly introduce a certain amount of stabilizer in the process of preparing zirconia-silicon carbide composite material through carbon thermal reduction of zircon, zircon sand or zirconium silicate. Such as MgO, CaO, Y ₂ O ₃ or CeO ₂ , etc., by controlling the temperature and reaction process of the carbon thermal reduction reaction of zircon, zircon sand or zirconium silicate, the zirconia-silicon carbide composite powder material can be realized in one step Preparation and transformation of monoclinic zirconia to cubic zirconia for the purpose. The invention has many advantages such as short technological process, little pollution in the production process, low energy consumption, low cost and high added value of products, etc., and is helpful for reducing the production cost of high-performance zirconia-β phase silicon carbide composite materials and the production cost of zircon, zirconium The efficient value-added utilization of non-metallic minerals such as British sand is of great significance.

Invention content:

The patent application of the present invention is to properly introduce a certain amount of stabilizers, such as MgO, CaO, Y ₂ O ₃ or CeO _2, etc., and by controlling the temperature and reaction process of the carbon thermal reduction reaction of zircon, zircon sand or zirconium silicate, the preparation of zirconia-silicon carbide composite high-temperature resistant powder materials can be realized in one step And the purpose of transforming monoclinic zirconia into cubic zirconia. The invention has many advantages such as short process flow, less pollution in the production process, lower cost, low energy consumption, and high added value of the product, and is useful for reducing the production cost of high-performance cubic zirconia-β-phase silicon carbide composite materials and zircon, The efficient value-added utilization of non-metallic minerals such as zircon sand is of great significance.

A method for preparing a cubic zirconia-β-phase silicon carbide composite high-temperature-resistant powder material proposed by the present invention is characterized in that: 0.1% to 99.0% of zircon, zircon sand or zirconium silicate based on the total mass of ingredients , and 0.1% to 99.0% carbon black, coke, graphite or activated carbon as raw materials, 0.1% to 99.0% MgO, CaO, _Y2O3 or _CeO2 as stabilizers based on the total mass of ingredients, after _batching and mixing, ball milling, Drying, molding and other processes to prepare the sample green body, in a closed reducing atmosphere selected from coke burial or in an inert gas selected from argon protection, at 1400 ° C ~ 1800 ° C for a reaction time of 0.1 hours ~ 100 hours, the preparation Obtain cubic zirconia-silicon carbide composite high temperature resistant powder material.

The zircon, zircon sand or zirconium silicate described in the above preparation method of cubic zirconia-β phase silicon carbide composite high temperature resistant powder material has a purity of not less than 80% by mass, and carbon black, coke , graphite or activated carbon, the carbon content is _not less than 60% by mass, and the purity of MgO, CaO, _Y2O3 or _CeO2 is not less than 90% by mass.

The pressure of the inert gas described in the preparation method of the cubic zirconia-beta phase silicon carbide composite phase high temperature resistant powder material is 0.1Pa-10.0MPa.

The coke-embedded airtight reducing atmosphere described in the preparation method of a cubic zirconia-β-phase silicon carbide composite high-temperature-resistant powder material is a test by embedding coke in a sagger container that can withstand high temperatures above 1800°C. Sample green body, and seal the high-temperature-resistant saggar container to isolate the sample and coke from the reducing atmosphere generated by the air.

A method for preparing a cubic zirconia-β-phase silicon carbide composite high-temperature-resistant powder material. In the obtained composite-phase high-temperature-resistant powder material, zirconia mainly exists in the form of cubic phase, and silicon carbide mainly exists in the form of β-phase.

A method for preparing a cubic zirconia-silicon carbide composite high-temperature-resistant powder material, wherein the process is specifically:

1) Raw materials such as zircon, zircon sand or zirconium silicate, carbon black, coke, graphite or activated carbon, and stabilizer are mixed in proportion and fully mixed, and then the mixed raw materials are put into a ball mill tank, and Ball milling in the ball mill for 0.1 to 50 hours until the raw materials are evenly dispersed. The ball milling method is dry ball milling or wet ball milling; then the ball milled uniform raw materials are made by dry pressing, semi-dry pressing or isostatic pressing. Blocky green sample;

2) Put the above-mentioned dried green body into a high-temperature-resistant saggar container that can withstand above 1800 ° C, and distribute coke or activated carbon particles with a particle size of 0.1 to 1.0 mm around the sample green body to make the coke or activated carbon particles Fully wrap around the sample green body, and then seal the high-temperature-resistant saggar container to ensure that the sample and coke are isolated from the air, so that the processed high-temperature-resistant saggar container can be placed in a corresponding thermal kiln for heating and firing. Its schematic diagram is shown in the attached drawing of the manual; or the above-mentioned dried sample green body is directly placed in a high-temperature atmosphere furnace protected by inert gas for high-temperature carbothermal reduction reaction, and the heat treatment process of the sample green body is often warmed to the synthesis temperature range There is no specific requirement for the heating rate. It can be kept at the corresponding temperature for a certain period of time. The reaction time is 0.1 hour to 100 hours at 1400 ° C ~ 1800 ° C. After cooling to room temperature naturally, take out the sample and grind it to obtain cubic Silicon oxide-β phase silicon carbide composite phase high temperature resistant powder material.

The present invention effectively controls the temperature and reaction process of zircon, zircon sand or zirconium silicate carbothermal reduction reaction, and realizes the preparation of zirconia-β phase silicon carbide powder material and monoclinic Phase zirconia is transformed into cubic phase zirconia, so it has many advantages such as less pollution in the production process, lower cost, low energy consumption, and high added value of products, which is helpful for reducing the production cost of cubic zirconia-β phase silicon carbide composite materials And the efficient value-added utilization of non-metallic minerals such as zircon and zircon sand is of great significance.

Description of drawings:

Accompanying drawing is the device schematic diagram of preparation cubic zirconia-beta phase silicon carbide composite high temperature resistant material under the airtight reducing atmosphere condition of coke burial (1-high temperature furnace wall; 2-heating body; 3-furnace hearth; ℃ high-temperature sagger container; 5-coke fine powder; 6-carbon paper; 7-coke particles; 8-sample green body; 9-high temperature resistant ceramic support)

Detailed ways:

Below in conjunction with example technical scheme of the present invention is described further:

First, mix various raw materials and additives according to the stated proportions, and then use a ball mill to dry or wet the ingredients for 0.1-50 hours until the raw materials are mixed uniformly, and then dry the uniformly mixed raw materials to form, semi-dry The sample green body of a certain shape is made by pressing or isostatic pressing, and then the cubic zirconia-β-phase silicon carbide composite high-temperature-resistant powder material is prepared by carbothermal reduction reaction under reducing atmosphere conditions. The specific process flow is:

Raw material→raw material pretreatment→batching→ball milling→drying→forming→green sample→drying→carbothermal reduction under reducing atmosphere conditions→grinding→cubic zirconia-β-phase silicon carbide composite phase high-temperature-resistant powder material

Example 1

Raw materials and ratio:

The particle size and quality requirements of zircon raw materials are that the ZrSiO ₄ content is greater than 80% by mass, and the ZrO ₂ content is greater than 50% by mass, and the particle size is ≤ 1mm; carbon black is used as the reducing agent, and the particle size of the carbon black reducing agent is The quality requirements are that the carbon content is greater than 98% by mass, the particle size is ≤1 μm, and the mass ratio of zircon and carbon black is 5:1; industrial pure yttrium oxide is used as an additive, and the amount of yttrium oxide is added by mass for an additional 10%.

crafting process:

The above-mentioned various raw materials are made into a sample green body of Φ20mm×20mm through batching, mixing, ball milling, drying, molding and other processes, and then the sample is placed in a coke-buried airtight high-temperature resistant In a sagger container, place the high temperature resistant container in a high temperature kiln with an oxidative atmosphere, heat it at 1600°C for 4 hours, then cool it down to room temperature naturally, then separate the sample and the coke around the sample, take out the sample and grind it finely That is, a multi-phase high-temperature-resistant powder material containing yttria-stabilized cubic zirconia and β-phase silicon carbide is obtained.

Reaction product characterization: The main phases in the sample after the carbon thermal reduction of zircon described in the above process are cubic phase zirconia and β-SiC.

Example 2

Raw materials and ratio:

The particle size and quality requirements of the zircon sand raw material are that the ZrSiO ₄ content is greater than 95% by mass, and the ZrO ₂ content is greater than 60% by mass, and the particle size is ≤ 1mm; activated carbon is used as the reducing agent, and the particle size and quality requirements are, The carbon content in the activated carbon is greater than 98% by mass, and the particle size is ≤1 μm; the mass ratio of zircon and activated carbon is 5:1; industrial pure magnesium oxide is used as an additive, and the added amount of magnesium oxide is an additional 8wt% by mass .

crafting process:

The above-mentioned various raw materials are made into a sample green body of Φ20mm×20mm through batching, mixing, ball milling, drying, molding and other processes, and the sample is placed in an open graphite crucible, and then the graphite crucible is placed in argon gas. After being kept at 1650°C for 6 hours in an atmosphere-protected high-temperature kiln, it is naturally cooled to room temperature. After the sample is taken out and ground, a composite high-temperature-resistant powder material containing magnesia-stabilized cubic zirconia and silicon carbide is obtained.

Reaction product characterization: The main phases in the sample after the carbon thermal reduction of zircon described in the above process are cubic phase zirconia and β-SiC.

Claims (5)

1. A preparation method of cubic zirconia-β-phase silicon carbide composite phase high-temperature-resistant powder material, characterized in that: 0.1% to 99.0% zircon, zircon sand or zirconium silicate in terms of total batching mass, and 0.1%~99.0% carbon black, coke, graphite or activated carbon as raw materials, 0.1%~ _99.0 % MgO, CaO, _Y2O3 or _CeO2 as stabilizers based on the total batching mass, after batching and mixing, ball milling, drying, The sample green body is prepared by molding and other processes. In a closed reducing atmosphere selected from coke burial or in an inert gas selected from argon protection, the reaction time is 0.1 hour to 100 hours at 1400 ° C ~ 1800 ° C, and the cubic Zirconia-β phase silicon carbide composite phase high temperature resistant powder material. 2. preparation method according to claim 1 is characterized in that: its purity of described zircon, zircon sand or zirconium silicate is not less than 80% by mass, and carbon black, coke, graphite or gac The carbon content is not less than 60% by mass, and the purity of MgO, CaO, Y ₂ O ₃ or CeO ₂ is not less than 90% by mass. 3. The preparation method according to claim 1, characterized in that: the airtight reducing atmosphere of coke burial is by using coke to bury the sample green body in a saggar container that can withstand high temperatures above 1800 ° C, and seal the high temperature resistant The sagger container isolates the sample and coke from the reducing atmosphere generated by the air. 4. The preparation method according to claim 1, characterized in that: the pressure of the inert gas is 0.1Pa˜10.0MPa. 5. The composite phase high temperature resistant powder material obtained by the preparation method according to claim 1, 2, 3 or 4, characterized in that in the composite powder material, zirconium oxide is mainly in the cubic phase, and silicon carbide is mainly in the form of β phase exist.

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