A method for preparing a high sintering activity (Zr, Ti) C-SiC composite ceramic powder

Abstract

The application provides a preparation method of a high-sintering-activity (Zr, Ti) C-SiC composite ceramic powder, which comprises the following steps: (1) preparing a composite ceramic precursor; (2) adding a magnesium salt and gelatinizing the precursor; and (3) preparing the composite ceramic powder through high-temperature carbon thermal reduction. Tetraethyl titanate is used as a titanium source, furfuryl alcohol is used as a carbon source, and the magnesium salt is used as a modifier. The addition of the magnesium salt can coat the ceramic powder in the form of amorphous Mg-Si-O oxide, thereby improving the sintering property of the ceramic powder. The composite ceramic powder prepared by the method has a lower production cost and a sintering activity far higher than that of a currently commercially used composite ceramic powder. A composite ceramic block with a relative density as high as 99.9% can be obtained through 1700 DEG C, 30MPa electric discharge plasma sintering for 10 min, and the composite ceramic block has a good application prospect in the fields of high-temperature resistance and ablation resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic powder preparation, and particularly relates to a preparation method of high-sintering-activity (Zr, Ti) C-SiC composite ceramic powder. BACKGROUND

[0002] (Zr, Ti) C-SiC is a ternary composite ultrahigh-temperature ceramic which can maintain good physical and chemical stability in high-temperature environments and reaction atmospheres. It combines the advantages of ZrC, TiC and SiC, has a suitable thermal expansion coefficient, high thermal conductivity, good oxidation resistance and ablation resistance, and can realize long-time non-ablation in high-temperature oxidation environments above 2000 DEG C, is a very promising non-ablation type ultrahigh-temperature heat-resistant material, and can be used to prepare the leading edges of hypersonic aircraft, nose cones and key hot end components of combustion chambers of scramjet engines. In the prior art, solid ceramic powder mixing sintering is usually used to prepare multi-element composite ceramics. However, due to the low sintering activity of ceramic powder, high-temperature and high-pressure conditions are usually required to obtain high-density (Zr, Ti) C-SiC composite ceramics, and the harsh sintering conditions seriously limit the practical application of the composite ceramics. Therefore, it is of great significance to find a preparation method of high-sintering-activity (Zr, Ti) C-SiC composite ceramic powder to optimize the harsh sintering conditions. SUMMARY

[0003] The technical problem to be solved by the application is to overcome the deficiencies and defects mentioned in the background, and to provide a preparation method of high-sintering-activity (Zr, Ti) C-SiC composite ceramic powder which is simple, easy to operate, has good dispersity and sintering activity.

[0004] To solve the above technical problems, the technical solution provided by the application is as follows:

[0005] A preparation method of high-sintering-activity (Zr, Ti) C-SiC composite ceramic powder, comprising the following steps:

[0006] (1) preparing a (Zr, Ti) C-SiC composite ceramic precursor solution: respectively dissolving tetraethyl orthosilicate and zirconium oxychloride to prepare a precursor solution containing silicon and zirconium, adding tetrabutyl titanate and furfuryl alcohol to the precursor solution containing silicon, stirring uniformly, and then adding the precursor solution containing zirconium to prepare a (Zr, Ti) C-SiC composite ceramic precursor solution;

[0007] (2) preparing a precursor dry gel powder: adding a magnesium salt to the (Zr, Ti) C-SiC composite ceramic precursor solution prepared in step (1), stirring to dissolve, and then aging the precursor solution to obtain a black-brown gel, drying and crushing to obtain a precursor dry gel powder;

[0008] (3) high temperature heat treatment: the precursor xerogel powder obtained in step (2) is calcined, thereby obtaining high sintering activity (Zr, Ti) C-SiC composite ceramic powder.

[0009] Tetraethyl titanate is used as the titanium source, furfuryl alcohol is used as the carbon source, and a magnesium salt is used as the modifier. The addition of the magnesium salt can coat the ceramic powder in the form of amorphous Mg-Si-O oxide, thereby improving the sintering activity of the ceramic powder.

[0010] Preferably, the solvent used for dissolving the tetraethyl orthosilicate and the zirconium oxychloride in step (1) is a mixed solution of water and ethanol in a volume ratio of 2-3:1.

[0011] Preferably, the molar ratio of the zirconium oxychloride to the tetraethyl titanate in step (1) is 1:(0.33-1), and the molar ratio of the tetraethyl orthosilicate to the zirconium oxychloride is (1-5):1.

[0012] Preferably, the magnesium salt in step (2) includes one or more of magnesium nitrate, magnesium sulfate, and magnesium chloride.

[0013] Preferably, the molar ratio of the magnesium salt to Mg:Si in the (Zr, Ti) C-SiC composite ceramic precursor solution in step (2) is 1:(2-5).

[0014] Preferably, the gel aging temperature in step (2) is 60-80°C, and the aging time is 0.5-2h.

[0015] Preferably, the gel drying temperature in step (2) is 100-150°C, and the drying time is 6-10h. The temperature will affect the size of the final ceramic particles.

[0016] Preferably, the calcination temperature in step (3) is 1500-1700°C, and the calcination time is 0.5-2h.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] 1. The present application uses a sol-gel process, which has low requirements for equipment and a wide source of raw materials.

[0019] 2. The black-brown gel obtained by the present application is prepared by a sol-gel process. During the sol process, the components of the reactants are mixed at the molecular level and fully crosslinked. In addition, the gel is in a colloidal state, and the solvent in the gel pores is mainly alcohol, which has small capillary force during the drying process, so that a composite ceramic precursor xerogel powder with little aggregation and loose structure can be easily obtained. Moreover, since a magnesium salt is introduced into the composite ceramic precursor, an amorphous Mg-Si-O oxide layer can be formed on the surface of the composite ceramic powder after high-temperature calcination, which can significantly improve the sintering activity of the composite ceramic powder.

[0020] 3. The prepared composite ceramic powder has low production cost and its sintering activity is much higher than that of the currently commercialized composite ceramic powder; a composite ceramic block with a relative density as high as 99.9% can be obtained by 1700℃, 30MPa discharge plasma sintering for 10min, and has a good application prospect in the field of high-temperature resistance and ablation-resistant environment. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0022] Fig. 1 is the XRD pattern of the product of the present application examples 1-4 and comparative example 1;

[0023] Fig. 2 is the SEM graph of the product of the present application examples 1-4 and comparative example 1;

[0024] Fig. 3 is the sintering curve graph of the product of the present application examples 1-4 and comparative example 1. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of the present application, the following will combine the drawings of the specification and the preferred embodiments to make a more comprehensive and detailed description of the present application, but the protection scope of the present application is not limited to the following specific embodiments.

[0026] Unless otherwise defined, all the professional terms used in the following have the same meaning as generally understood by those skilled in the art. The professional terms used in this paper are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present application.

[0027] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0028] Example 1:

[0029] A preparation method of a high-sintering-activity (Zr, Ti) C-SiC composite ceramic powder, comprising the following steps:

[0030] (1) Preparation of (Zr, Ti)C-SiC composite ceramic precursor: tetraethyl orthosilicate and zirconium oxychloride are dissolved in a mixed solution of water and alcohol with a volume ratio of 2:1, respectively, to prepare an organic silicic acid solution with a concentration of 2.56 mol / L and a zirconium inorganic salt solution with a concentration of 1 mol / L; then 2 mol of tetrabutyl titanate and 16.68 mol of furfuryl alcohol are sequentially added to the silicon-containing precursor solution, and after uniform stirring, the zirconium-containing precursor solution is added to prepare a (Zr, Ti)C-SiC composite ceramic precursor solution.

[0031] (2) According to the molar ratio of Mg:Si of 1:2, magnesium chloride is added to the (Zr, Ti)C-SiC composite ceramic precursor solution while stirring, and after uniform stirring, the gel is aged at 60°C for 1 h to obtain a black-brown gel; the prepared gel is moved to an oven at 120°C for drying treatment to obtain a dry gel; then the dry gel is ball-milled and broken for storage.

[0032] (3) High-temperature heat treatment: the ball-milled and broken dry gel powder is high-temperature calcined, the calcination temperature is 1600°C, and the calcination time is 1 h. A high-sintering-activity (Zr, Ti)C-SiC composite ceramic powder is obtained.

[0033] Example 2:

[0034] A method for preparing a high-sintering-activity (Zr, Ti)C-SiC composite ceramic powder, comprising the following steps:

[0035] (1) Preparation of (Zr, Ti)C-SiC composite ceramic precursor: tetraethyl orthosilicate and zirconium oxychloride are dissolved in a mixed solution of water and alcohol with a volume ratio of 2:1, respectively, to prepare an organic silicic acid solution with a concentration of 2.56 mol / L and a zirconium inorganic salt solution with a concentration of 1 mol / L; then 2 mol of tetrabutyl titanate and 16.68 mol of furfuryl alcohol are sequentially added to the silicon-containing precursor solution, and after uniform stirring, the zirconium-containing precursor solution is added to prepare a (Zr, Ti)C-SiC composite ceramic precursor solution.

[0036] (2) According to the molar ratio of Mg:Si of 1:2, magnesium chloride is added to the (Zr, Ti)C-SiC composite ceramic precursor solution while stirring, and after uniform stirring, the gel is aged at 60°C for 1 h to obtain a black-brown gel; the prepared gel is moved to an oven at 120°C for drying treatment to obtain a dry gel; then the dry gel is ball-milled and broken for storage.

[0037] (3) High-temperature heat treatment: the ball-milled and broken dry gel powder is high-temperature calcined, the calcination temperature is 1600°C, and the calcination time is 1 h. A high-sintering-activity (Zr, Ti)C-SiC composite ceramic powder is obtained.

[0038] Example 3:

[0039] A preparation method of a high-sintering-activity (Zr, Ti) C-SiC composite ceramic powder, comprising the following steps:

[0040] (1) Preparation of a (Zr, Ti) C-SiC composite ceramic precursor: tetraethyl orthosilicate and zirconium oxychloride are respectively dissolved in a mixed solution of water and alcohol at a volume ratio of 2:1 to prepare an organic silicic acid solution with a concentration of 2.56 mol / L and a zirconium inorganic salt solution with a concentration of 2 mol / L; then 1 mol of tetrabutyl titanate and 16.68 mol of furfuryl alcohol are added to the silicon-containing precursor solution, and after uniform stirring, the zirconium-containing precursor solution is added to prepare a (Zr, Ti) C-SiC composite ceramic precursor solution.

[0041] (2) According to the molar ratio of Mg:Si of 1:2, magnesium chloride is added to the (Zr, Ti) C-SiC composite ceramic precursor solution while stirring, and after uniform stirring, the gel is aged at 60°C for 1 h to obtain a black-brown gel; the prepared gel is moved to a drying oven at 120°C for drying treatment to obtain a dry gel; then the dry gel is ball-milled and broken for storage.

[0042] (3) High-temperature heat treatment: the ball-milled and broken dry gel powder is high-temperature calcined at a calcining temperature of 1600°C for 1 h to obtain a high-sintering-activity (Zr, Ti) C-SiC composite ceramic powder.

[0043] Example 4:

[0044] A preparation method of a high-sintering-activity (Zr, Ti) C-SiC composite ceramic powder, comprising the following steps:

[0045] (1) Preparation of a (Zr, Ti) C-SiC composite ceramic precursor: tetraethyl orthosilicate and zirconium oxychloride are respectively dissolved in a mixed solution of water and alcohol at a volume ratio of 2:1 to prepare an organic silicic acid solution with a concentration of 2.56 mol / L and a zirconium inorganic salt solution with a concentration of 3 mol / L; then 1 mol of tetrabutyl titanate and 19.68 mol of furfuryl alcohol are added to the silicon-containing precursor solution, and after uniform stirring, the zirconium-containing precursor solution is added to prepare a (Zr, Ti) C-SiC composite ceramic precursor solution.

[0046] (2) According to the molar ratio of Mg:Si of 1:2, magnesium chloride is added to the (Zr, Ti) C-SiC composite ceramic precursor solution while stirring, and after uniform stirring, the gel is aged at 60°C for 1 h to obtain a black-brown gel; the prepared gel is moved to a drying oven at 120°C for drying treatment to obtain a dry gel; then the dry gel is ball-milled and broken for storage.

[0047] (3) High temperature heat treatment: the dry gel powder after ball milling is calcined at high temperature, the calcination temperature is 1600℃, and the calcination time is 1h. The high sintering active (Zr, Ti) C-SiC composite ceramic powder is obtained.

[0048] Comparative Example 1:

[0049] A preparation method of a (Zr, Ti) C-SiC composite ceramic powder, comprising the following steps:

[0050] (1) Preparation of (Zr, Ti) C-SiC composite ceramic precursor: tetraethyl orthosilicate and zirconium oxychloride are respectively dissolved in a mixed solution of water and alcohol with a volume ratio of 2:1, and are respectively configured into an organic silicon acid solution with a concentration of 2.56 mol / L and a zirconium inorganic salt solution with a concentration of 1 mol / L; then 1 mol of tetrabutyl titanate and 13.68 mol of furfuryl alcohol are added to the silicon-containing precursor solution, and after stirring uniformly, the zirconium-containing precursor solution is added, to obtain a (Zr, Ti) C-SiC composite ceramic precursor solution.

[0051] (2) The (Zr, Ti) C-SiC composite ceramic precursor solution is aged at 60℃ for 1h to obtain a black-brown gel.

[0052] (3) The prepared gel is moved to an oven at 120℃ for drying treatment to obtain a dry gel; then the dry gel is ball milled and broken to be reserved for use.

[0053] (4) High temperature heat treatment: the dry gel powder after ball milling is calcined at high temperature, the calcination temperature is 1600℃, and the calcination time is 1h. The (Zr, Ti) C-SiC composite ceramic powder is obtained.

[0054] In order to test the high sintering property of the composite ceramic powder provided by the application, the composite ceramic powder obtained by the examples and the comparative example is tested by X-ray diffraction, scanning electron microscope and discharge plasma sintering, and the test results are shown in Figs. 1 to 3 and Table 1.

[0055] Specifically, Fig. 1 is the XRD pattern of the products of Examples 1-4 and Comparative Example 1 of the application, and from the figure it can be seen that the composite ceramic powder contains SiC, TiC-rich (Zr, Ti) C and ZrC-rich (Zr, Ti) C three crystal phases. Fig. 2 is the scanning electron microscope graph of the products of Examples 1-4 and Comparative Example 1 of the application, and from Fig. 2 it can be seen that the prepared composite ceramic powder has uniform size and the particle size reaches nanometer level.

[0056] Fig. 3is the sintering curve of the product of the examples 1-4 and the comparative example 1 of the present application, from the figure it can be seen that the four kinds of composite ceramic powder added with magnesium salt (examples 1-4) start to sinter and densify rapidly at 1270℃, and the sintering process is basically completed after 1700℃, 30MPa, 200s; while the comparative example 1 without adding magnesium salt starts to sinter and densify at 1460℃, and the sample still does not complete the sintering process after 1700℃, 30MPa, 600s. Table 1 is the open porosity and relative density of the product of examples 1-4 and the comparative example 1 after sintering, from the table it can be seen that the relative density of the ceramic block after sintering of the four kinds of composite ceramic powder added with magnesium salt (examples 1-4) is all greater than 99.5%; among them, the relative density of example 2 reaches 99.9%, which is obviously higher than that of the comparative example 1 without adding magnesium salt (relative density 95.1%).

[0057] Table 1 open porosity and relative density of the product of examples 1-4 and the comparative example 1 after sintering

[0058]

Claims

1. A method for producing a high sintering activity (Zr,Ti)C-SiC composite ceramic powder, characterized by, The method comprises the following steps: (1) preparing a (Zr, Ti)C-SiC composite ceramic precursor solution: dissolving tetraethyl orthosilicate and zirconium oxychloride respectively to prepare a precursor solution containing silicon and zirconium, adding tetrabutyl titanate and furfuryl alcohol to the precursor solution containing silicon, and then adding the precursor solution containing zirconium after uniform stirring to prepare the (Zr, Ti)C-SiC composite ceramic precursor solution; the molar ratio of zirconium oxychloride to tetrabutyl titanate is 1: (0.33-1), and the molar ratio of tetraethyl orthosilicate to zirconium oxychloride is (1-5): 1; (2) preparing a precursor xerogel powder: adding a magnesium salt to the (Zr, Ti)C-SiC composite ceramic precursor solution prepared in step (1), stirring to dissolve, and then allowing the precursor solution to gel and age to obtain a black-brown gel, drying and crushing to obtain the precursor xerogel powder; (3) high-temperature heat treatment: calcining the precursor xerogel powder obtained in step (2) to obtain a high-sintering-activity (Zr, Ti)C-SiC composite ceramic powder.

2. The production method according to claim 1, characterized by, In step (1), the solvent for dissolving tetraethyl orthosilicate and zirconium oxychloride is a mixed solution of water and ethanol in a volume ratio of 2:

1.

3. The production method according to claim 1, characterized by, The magnesium salt in step (2) comprises one or more combinations of magnesium nitrate, magnesium sulfate and magnesium chloride.

4. The method of claim 1, wherein, In step (2), the molar ratio of Mg in the magnesium salt to Si in the (Zr, Ti)C-SiC composite ceramic precursor solution is 1: (2-5).

5. The preparation method according to claim 1, characterized in that, In step (2), the gel aging temperature is 60-80 °C, and the aging time is 0.5-2 h.

6. The production method according to claim 1, characterized by, In step (2), the gel drying temperature is 100-150 °C, and the drying time is 6-10 h.

7. The production method according to claim 1, characterized by, In step (3), the calcination temperature is 1500-1700 °C, and the calcination time is 0.5-2 h.

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