CN107253864B

CN107253864B - Ceramic composite material forming method and ceramic composite material

Info

Publication number: CN107253864B
Application number: CN201710565784.6A
Authority: CN
Inventors: 李正申
Original assignee: Zhengzhou Qianshun New Material Technology Co ltd
Current assignee: Hunan Feihang Material Technology Co.,Ltd.
Priority date: 2017-07-12
Filing date: 2017-07-12
Publication date: 2020-09-18
Anticipated expiration: 2037-07-12
Also published as: CN107253864A

Abstract

The invention provides a ceramic composite material forming method and a ceramic composite material, and relates to the technical field of ceramic composite material forming. The forming method comprises the steps of pre-dipping fibers in slurry, directly weaving with the slurry, continuously injecting the slurry into gaps formed among the fibers in the weaving process, drying and sintering the woven prefabricated body without dipping, and thus obtaining the ceramic composite material; the ceramic composite material prepared by the forming method can easily reach the required density. The invention also provides a ceramic composite material which has good compactness.

Description

Ceramic composite material forming method and ceramic composite material

Technical Field

The invention relates to the technical field of ceramic composite material forming, in particular to a ceramic composite material forming method and a ceramic composite material.

Background

The fiber reinforced ceramic composite material is a material compounded by taking fiber as a reinforcement and ceramic as a matrix. The introduction of the high-performance fiber can toughen and strengthen the ceramic, prevent cracks and improve the mechanical property of the ceramic, and the formed ceramic composite material has excellent properties of high temperature resistance, high strength, high modulus, ablation resistance, scouring resistance and the like, has wide application in the fields of aerospace, chemical industry, metallurgy and the like, and can be particularly used as a ceramic thermal protection material, a high-temperature wave-transmitting antenna cover, a high-temperature wave-transmitting antenna window, a crucible for metallurgy, a flame nozzle and the like.

However, the existing ceramic composite material has complex molding process, high cost and long production period. Specifically, the molding process of the traditional ceramic composite material mainly comprises the following steps: preparing a prefabricated body by adopting fibers; (II) soaking the prefabricated body into the slurry, drying, and repeatedly soaking and drying until the required density is achieved; and thirdly, sintering the dried prefabricated member to obtain the ceramic composite material. Wherein, the workload of the step (I) and the step (II) accounts for more than 80 percent of the total workload of the whole forming process. Particularly, in the dipping process in the step (II), since the slurry is difficult to dip into the interior of the preform, the dipping efficiency is low, and the dipping process is often repeated for more than dozens of times, which not only greatly increases the workload, but also prolongs the production period and increases the production cost. In addition, although the degree of impregnation is generally increased to increase the degree of densification of the ceramic composite material, even if the impregnation is performed several tens of times, problems such as insufficient densification inside the ceramic composite material tend to occur.

In view of this, the present invention proposes a technical solution.

Disclosure of Invention

The invention aims to provide a method for forming a ceramic composite material, which is characterized in that fibers are soaked in slurry in advance and then are directly woven with the slurry, the slurry is continuously injected into gaps formed among the fibers in the weaving process, and a prefabricated body obtained by weaving does not need to be soaked and is directly dried and sintered to obtain the ceramic composite material.

A second object of the present invention is to provide a ceramic composite material.

In order to achieve the above purpose of the present invention, the following technical solutions are adopted:

the invention provides a ceramic composite material forming method, which comprises the following steps:

(a) dipping the fiber in the slurry;

(b) placing the fiber soaked with the slurry on a mold for weaving to obtain a prefabricated body;

wherein, in the weaving process, slurry is injected into gaps formed among the fibers;

(c) and drying, demolding and sintering the prefabricated body to obtain the ceramic composite material.

Further, in the step (a), ultrasonic dispersion is performed during impregnation so that the slurry penetrates into the inside of the fiber.

Further, in the step (b), the slurry is injected into the space formed between the fibers through the injection nozzle.

Further, the slurry is prepared by mixing ceramic particles, a solution and a stabilizer and then grinding;

wherein the solution is sol or precursor solution.

Further, the ceramic particles are selected from one or a combination of at least two of silicon oxide, silicon carbide, aluminum oxide, zirconium oxide, mullite, silicon nitride, boron nitride, hafnium carbide, hafnium boride or zirconium boride.

Further, the solution is selected from one or a combination of at least two of silica sol, alumina sol, zirconia sol or mullite sol;

or the solution is selected from one or the combination of at least two of silicon carbide precursor solution, silicon nitride precursor solution, boron nitride precursor solution, hafnium carbide precursor solution, hafnium boride precursor solution or zirconium boride precursor solution.

Further, the structure of the prefabricated body is one of a three-dimensional orthogonal structure, a quasi-three-dimensional orthogonal structure, a two-dimensional half structure, a three-dimensional four-way structure, a three-dimensional five-way structure or a needling structure.

Further, the fiber is selected from one or a combination of at least two of carbon fiber, quartz fiber, silicon carbide fiber, alumina fiber, silicon nitride fiber or boron nitride fiber.

Further, the ceramic composite material forming method comprises the following steps:

(a) soaking the fiber in the slurry, and enabling the slurry to permeate into the fiber by adopting ultrasonic dispersion;

the slurry is prepared by mixing ceramic particles, a solution and a stabilizer and then grinding;

(b) placing the fibers soaked with the slurry on a mold for weaving, and injecting the slurry into gaps formed among the fibers through a jet nozzle in the weaving process until the weaving is finished to obtain a prefabricated body;

The invention also provides a ceramic composite material which is prepared by adopting the ceramic composite material forming method.

Compared with the prior art, the ceramic composite material forming method and the ceramic composite material provided by the invention have the following beneficial effects:

(1) the invention has provided a ceramic composite material forming method, this forming method is after soaking the fiber in the slurry in advance, weave with the slurry directly, and pour into slurry into the space formed among the fiber continuously in the course of weaving, weave the prefabricated body that gets, do not need to soak, dry, sinter directly, can get the ceramic composite material, this forming method has saved the process that needs to soak the prefabricated body repeatedly in the traditional forming process, the process is greatly simplified, has reduced the work load, has shortened the production cycle, and then has saved the working cost, has improved the complicated defect of forming process of the traditional forming process, with high costs and production cycle length; in addition, the ceramic composite material prepared by the forming method can easily reach the required compactness.

(2) The invention provides a ceramic composite material which is prepared by the ceramic composite material forming method and has good density.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic view of a conventional process for forming a ceramic composite material;

FIG. 2 is a schematic flow chart of a method for forming a ceramic composite material provided by the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. 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.

According to an aspect of the present invention, there is provided a ceramic composite molding method including the steps of:

(a) dipping the fiber in the slurry;

(b) placing the fibers soaked with the slurry on a mold for weaving, and injecting the slurry into gaps formed among the fibers in the weaving process until the weaving is finished to obtain a prefabricated body;

The forming process of the traditional ceramic composite material mainly comprises the following steps: preparing a prefabricated body by adopting fibers; (II) soaking the prefabricated body into the slurry, drying, repeatedly soaking and drying until the required density is achieved; and thirdly, sintering the dried prefabricated member to obtain the ceramic composite material. Wherein, the workload of the step (I) and the step (II) accounts for more than 80 percent of the total workload of the whole forming process. Particularly, in the dipping process in the step (II), since the slurry is difficult to dip into the interior of the preform, the dipping efficiency is low, and the dipping process is often repeated for more than dozens of times, which not only greatly increases the workload, but also prolongs the production period and increases the production cost. In addition, although the density of the ceramic composite material is generally increased by increasing the number of times of impregnation, problems such as insufficient internal density of the ceramic composite material tend to occur even after several tens of times of impregnation.

In order to solve the problems, the invention provides a method for forming a ceramic composite material, which is characterized in that fibers are soaked in slurry in advance and then are directly woven with the slurry, the slurry is continuously injected into gaps formed among the fibers in the weaving process, and a prefabricated body obtained by weaving is not required to be soaked and is directly dried and sintered to obtain the ceramic composite material. The ceramic composite material forming method is simplified, and good technical effects can be achieved.

Specifically, in a preferred embodiment of the present invention, the fiber is selected from one or a combination of several of carbon fiber, quartz fiber, silicon carbide fiber, alumina fiber, silicon nitride fiber or boron nitride fiber.

By further defining the type of the fibers, the mechanical properties of the ceramic material can be further enhanced.

The slurry used to impregnate the fibers consists essentially of ceramic particles, a solution, and a stabilizer. The content of each component in the slurry is set according to actual needs.

The term "comprising" as used herein means that it may include, in addition to the recited steps, other components which impart different properties to the slurry. In addition, the term "comprising" as used herein may be replaced by "being" or "consisting of … …" as closed.

For the ceramic particles, ceramic particles with different particle sizes are configured by adopting a particle grading method. The particle size distribution is also called particle size distribution. Continuous gradation composed of uninterrupted particle sizes of various levels; a discontinuous gradation consisting of only a certain number of levels of granularity. Reasonable particle size distribution is an important way to achieve low porosity in the furnish.

The reasonable particle composition can enable smaller ceramic particles to replace the space occupied by the solution among large ceramic particles, thereby reducing the required solution amount and improving the solid content of the slurry. Meanwhile, the solution in the gaps of the original larger particles is released by the smaller ceramic particles, so that the content of the free solution in the slurry can be improved, and the fluidity of the slurry is improved.

For the present invention, the grading of the ceramic particles between different particle sizes makes the particles in the slurry less prone to settling and the slurry more stable.

Typical but non-limiting ceramic particles may be 200 mesh, 300 mesh, 500 mesh, 700 mesh, 900 mesh, 1100 mesh, 1200 mesh or 1500 mesh in size, i.e., ceramic particles of different sizes as described above are selected for configuration for addition to the slurry.

The kind of the ceramic particles may be various. In a preferred embodiment of the invention, the ceramic particles are selected from one or a combination of at least two of silicon oxide, silicon carbide, aluminum oxide, zirconium oxide, mullite, silicon nitride, boron nitride, hafnium carbide, hafnium boride or zirconium boride.

Typically, the solids content of the ceramic particles in the slurry is 30-80%.

Typical, but non-limiting, ceramic particles have a solids content of 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%.

The solution is an important component in the slurry, and in the present invention, the solution is a sol or a precursor solution. The sol or precursor solution with proper viscosity and good stability is needed to be selected as the solution.

In a preferred embodiment of the present invention, the solution is selected from one or a combination of at least two of silica sol, alumina sol, zirconia sol or mullite sol;

The selection of the slurry has certain requirements, the slurry with high ceramic content and good fluidity needs to be selected, the slurry under the requirements has certain stability, and the sedimentation as less as possible in the dipping process can be ensured, so that the full infiltration of the slurry to the fibers is ensured. In the invention, the addition of the stabilizer is just a means for improving the stability of the slurry.

In a preferred embodiment of the present invention, the slurry may be prepared by mixing ceramic particles having different particle sizes prepared by a particle size classification method, a solution, and a stabilizer, and then grinding the mixture.

The grinding is preferably ball milling, and the ball milling can ensure that all components are fully ground, and contributes to obtaining slurry with good stability and fluidity.

In order to bring the pulp into sufficient contact with the fibers, in a preferred embodiment of the invention, the impregnation is carried out with ultrasonic dispersion so that the pulp penetrates into the interior of the fibers.

The dispersion and stability can be further improved by performing ultrasonic vibration stirring on the slurry. The slurry has certain stability, can ensure that the sedimentation is as little as possible in the dipping process, and avoids the phenomenon that the pores are blocked and sealed because the ceramic particles are sedimentated and enriched on the surface of the fiber, so that the material is porous and has more defects.

The process of dipping the fibers into the slurry and ultrasonically dispersing the fibers can be realized by means of a dipping tank with an ultrasonic dispersing function.

Because the ceramic composite material is formed by a certain mould, a certain machining allowance is reserved according to a product digifax, and the mould for weaving is machined.

And (3) passing the yarn to be used through the slurry-storing soaking tank with the ultrasonic dispersion function, and starting an ultrasonic dispersion switch to enable the yarn to fully absorb the slurry and then conveying the yarn to a mold position for weaving or fabric manufacturing, namely weaving with the slurry.

The 'weaving with pulp' in the invention refers to weaving by using fibers soaked with pulp, and in the weaving process, gaps among the fibers are filled with the pulp, which is mainly different from the fibers or fiber bundles which are not subjected to impregnation treatment in the traditional weaving.

During weaving or fabric manufacturing, voids may form between the fibers or fiber bundles. In a preferred embodiment of the invention, the pulp is injected into the interstices formed between the fibres by means of jet nozzles.

The pulp is continuously filled between the fibers or the fiber bundles through the installed pulp jet nozzle, so that a compact structure can be formed inside the yarn bundles and among the yarn bundles until the weaving or the fabric manufacturing is finished, and a prefabricated body is obtained.

In a preferred embodiment of the invention, the structure of the preform is one of a three-dimensional orthogonal, quasi-three-dimensional orthogonal, two-dimensional half, three-dimensional four-way, three-dimensional five-way or needle-punched structure.

It should be noted that in the present invention, "three dimensions" is equivalent to "three dimensions", "three-dimensional orthogonal" is equivalent to "three orthogonal directions", "quasi-three-dimensional orthogonal" is equivalent to "pseudo-three-dimensional orthogonal" or "near-three-dimensional orthogonal" or "quasi-orthogonal three-dimensional directions", and "two-dimensional half" is equivalent to "2.5D" or "two-dimensional half".

The preform is dried in an oven and the sol gel or precursor can be crosslinked while removing the solvent. And after drying, removing the die, and sintering at high temperature to form the ceramic composite material. The drying, demolding and sintering steps are identical to those of the existing molding method and are not described in detail here.

In the conventional method for preparing the fiber-reinforced ceramic composite material, the two steps of preparing the preform and compositing the ceramic matrix are separated, i.e. the preform is woven by fibers, and then the preform and the ceramic matrix are composited, and the specific forming process flow diagram is shown in fig. 1. In the invention, the fiber is soaked in the slurry in advance, the fiber belt is directly woven by the slurry, the slurry is continuously injected into gaps formed among the fibers in the weaving process, the prefabricated body obtained by weaving is not required to be soaked, and the prefabricated body is directly dried and sintered to obtain the ceramic composite material, wherein the flow diagram of the specific forming method is shown in figure 2.

Compared with the prior art, the weaving of the fabric and the compounding of the ceramic matrix are synchronously carried out, and the direct forming is carried out, so that the complex procedure that the prefabricated body needs to be repeatedly soaked and dried in the traditional forming process is avoided, the process is greatly simplified, the workload is reduced, the production cycle is shortened, and the working cost is further saved; the ceramic composite material prepared by the forming method can easily reach the required density.

According to another aspect of the invention, the ceramic composite material is prepared by the ceramic composite material forming method, and has good compactness.

The present invention will be further described with reference to the following examples.

Example 1

A method for forming a ceramic composite material comprises the following steps:

(a) dipping the fiber in the slurry;

specifically, the preparation method of the slurry mainly comprises the following steps:

quartz powder (SiO) with particle size of 300 mesh, 500 mesh, 700 mesh, 900 mesh, 1100 mesh and 1500 mesh₂99.9 percent of the raw materials are added into high-purity silica sol with the solid content of 23 percent according to the weight ratio of 1:1:2:2:3:1, a proper amount of quartz powder is added according to the principle that the solid content of the slurry is 76 percent, then lactic acid is added according to 1 percent of the weight of the slurry, the materials are mixed and then ball milled in a ball milling tank for 3.5 hours at the rotating speed of 450r/min to obtain the slurry;

the method comprises the steps of placing slurry in a soaking tank with an ultrasonic dispersion function, placing fibers to be woven in the slurry for soaking, starting an ultrasonic dispersion switch, and performing ultrasonic dispersion on the slurry and the fibers simultaneously, so that the slurry is fully soaked in the fibers.

(b) Processing of the die: preparing a conical metal die with the bottom end diameter of 350mm and the height of 670mm by a machining method according to a product digital model;

placing the fiber or fiber bundle soaked with the sizing agent obtained in the step (a) on a mould for weaving, wherein the specification of warp and weft yarns is 600tex untwisted yarns, the warp density is 8/cm, and the weft density is 3/cm; the specification of the normal yarns is 400tex non-twisted yarns, and the spacing distance is 4 mm;

in the weaving process, slurry is injected into gaps formed among fibers or fiber bundles by a method of extruding through a jet nozzle until weaving is finished to obtain a prefabricated body;

different weaving modes are selected according to different structures of the prefabricated body. In this embodiment, the preform adopts a quasi-three-dimensional orthogonal knitting structure, and the specific knitting manner is not described herein again;

wherein the thickness of the prefabricated body is controlled to be about 20 mm.

(c) Drying the preform obtained in step (b) at 120 ℃ for 3h, and then demoulding. And (3) placing the demoulded prefabricated body in a high-temperature furnace, sintering for 2h at 950 ℃, cooling and processing to the specified thickness to obtain the ceramic composite material, in particular to the ceramic composite material antenna housing with the quasi-three-dimensional orthogonal woven structure.

Example 2

(a) dipping the fiber in the slurry;

adding silicon carbide powder with the particle sizes of 200 meshes, 300 meshes, 500 meshes, 700 meshes, 900 meshes, 1100 meshes and 1200 meshes into a precursor solution with the solid content of 20% according to the weight ratio of 1:1:1:2:2:3:1, adding a proper amount of silicon carbide powder according to the principle that the solid content of slurry is 70%, then adding lactic acid according to 1% of the weight of the slurry, mixing the materials, and grinding for 3 hours in a ball milling tank at the rotating speed of 500r/min to obtain slurry;

(b) Processing of the die: preparing a conical metal die with the diameter of 300mm at the bottom end and the height of 650mm by adopting a machining method according to a product digifax;

placing the fiber or fiber bundle soaked with the sizing agent obtained in the step (a) on a mould for weaving with sizing agent, wherein the specification of warp and weft yarn is 600tex untwisted yarn, the warp density is 8 pieces/cm, and the weft density is 3 pieces/cm; the specification of the normal yarns is 400tex non-twisted yarns, and the spacing distance is 3 mm;

Example 3

(a) dipping the fiber in the slurry;

quartz powder with particle sizes of 300 meshes, 500 meshes, 700 meshes, 900 meshes, 1100 meshes and 1500 meshes is respectively prepared(SiO₂99.9 percent of the total weight of the raw materials, adding the mixture into high-purity silica sol with the solid content of 23 percent according to the weight ratio of 1:1:2:2:3:1, adding a proper amount of quartz powder according to the principle that the solid content of the slurry is 71 percent, then adding lactic acid according to 1 percent of the weight of the slurry, mixing the materials, and performing ball milling for 3.5 hours in a ball milling tank at the rotating speed of 450r/min to obtain the slurry.

The slurry is placed in a soaking tank with an ultrasonic dispersion function, the fiber to be woven is placed in the slurry for soaking, and an ultrasonic dispersion switch is turned on, so that the slurry is fully soaked in the fiber.

(b) Processing of the die: according to the product digital model, a conical wood mold with the bottom end diameter of 350mm and the height of 670mm is prepared by adopting a machining method.

And (b) placing the fiber or fiber bundle soaked with the sizing agent obtained in the step (a) on a mould for weaving, wherein the specification of the warp and weft yarns is 400tex untwisted yarn, and the warp density and the weft density are both 4 pieces/cm. Adhering the fiber soaked with the slurry on the surface of the mold, spraying the slurry on the surface of the fiber once each layer is laid, and puncturing once every 2mm by using a puncturing needle, so that the thickness gradually reaches about 20 mm.

And injecting slurry into gaps formed among the fibers or fiber bundles by a method of extruding through a jet nozzle in the weaving process until the weaving is finished to obtain a prefabricated body.

Different weaving modes are selected according to different structures of the prefabricated body. In this embodiment, the preform has a needle-punched structure, and the specific knitting method is not described herein again;

(c) Drying the preform obtained in step (b) at 120 ℃ for 3h, and then demoulding. And (3) placing the demoulded prefabricated body in a high-temperature furnace, sintering for 2h at 950 ℃, cooling and processing to the specified thickness to obtain the ceramic composite material, in particular to the ceramic composite material radome with the needling structure.

Example 4

(a) dipping the fiber in the slurry;

adding alumina with the particle sizes of 300 meshes, 500 meshes, 700 meshes, 900 meshes, 1100 meshes and 1500 meshes into high-purity silica sol with the solid content of 25% according to the weight ratio of 1:2:2:2: 1, adding a proper amount of alumina according to the principle that the solid content of the slurry is 78%, then adding lactic acid according to 1% of the weight of the slurry, mixing the materials, and performing ball milling for 4 hours in a ball milling tank at the rotating speed of 400r/min to obtain the slurry.

In conclusion, the ceramic composite material forming method provided by the invention is simple and efficient, the working procedure of repeatedly dipping the prefabricated body in the traditional forming process is omitted, the workload is greatly reduced, the production period is shortened, the working cost is further saved, and the ceramic composite material prepared by the forming method can easily reach the required density.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ceramic composite material forming method is characterized by comprising the following steps:

(a) soaking the fiber in the slurry, and performing ultrasonic dispersion on the slurry and the fiber simultaneously;

(b) placing the fibers soaked with the slurry on a cone mould for weaving, and injecting the slurry into gaps formed among the fibers in the weaving process until the weaving is finished to obtain a prefabricated body; the structure of the prefabricated body is one of a three-dimensional orthogonal structure, a quasi-three-dimensional orthogonal structure, a two-dimensional half-dimensional structure, a three-dimensional four-dimensional structure, a three-dimensional five-dimensional structure or a needling structure;

2. The method of claim 1, wherein the step (a) of dipping is carried out by ultrasonic dispersion so that the slurry is infiltrated into the inside of the fiber.

3. The method of claim 1, wherein the slurry is injected into the gaps formed between the fibers by a jet nozzle in the step (b).

4. The method for molding a ceramic composite material according to claim 1, wherein the slurry is prepared by mixing ceramic particles, a solution and a stabilizer, and then grinding;

wherein the solution is sol or precursor solution.

5. The method of claim 4, wherein the ceramic particles are selected from one or a combination of at least two of silicon oxide, silicon carbide, aluminum oxide, zirconium oxide, mullite, silicon nitride, boron nitride, hafnium carbide, hafnium boride, or zirconium boride.

6. The ceramic composite molding method according to claim 4, wherein the solution is selected from one or a combination of at least two of silica sol, alumina sol, zirconia sol, or mullite sol;

7. The method of any one of claims 1 to 6, wherein the fibers are selected from one or a combination of at least two of carbon fibers, quartz fibers, silicon carbide fibers, alumina fibers, silicon nitride fibers, or boron nitride fibers.

8. The method of forming a ceramic composite according to any one of claims 1 to 6, comprising the steps of:

(a) soaking the fiber in the slurry, and performing ultrasonic dispersion during soaking to enable the slurry to permeate into the fiber;

(b) placing the fibers soaked with the slurry on a conical die for weaving, and injecting the slurry into gaps formed among the fibers through a jet nozzle in the weaving process until the weaving is finished to obtain a prefabricated body;