阅读说明：本技术 制备陶瓷基复合材料的方法 (Method for preparing ceramic matrix composite material ) 是由 J·塔格特 于 2019-01-17 设计创作，主要内容包括：公开了一种制备陶瓷基复合材料的方法。用包含溶剂、基质粘合剂和颗粒的浆料对预制件进行一次或多次浸渗。通过利用溶剂和粘合剂之间不同的化学或物理性能,实现浸渗之间的溶剂去除。(A method of making a ceramic matrix composite is disclosed. The preform is infiltrated one or more times with a slurry comprising a solvent, a matrix binder, and particles. Solvent removal between impregnations is achieved by exploiting the different chemical or physical properties between the solvent and the binder.)

1. A method of making a ceramic matrix composite comprising:

impregnating the woven preform with a slurry having a solvent, a matrix binder, and solid particles;

removing at least some of the solvent without curing the matrix binder; and

repeating the infiltrating and removing the solvent until desired characteristics of the preform are obtained,

wherein the desired characteristic is at least one selected from the group consisting of density, porosity, and fiber volume fraction.

2. The method of claim 1, wherein the removing at least some of the solvent comprises utilizing a difference in chemical or physical properties between the solvent and the matrix binder.

3. The method of claim 2, wherein the chemical or physical property is boiling point temperature.

4. The method of claim 2, wherein the chemical or physical property is vapor pressure.

5. The method of claim 3, comprising:

infiltrating the preform with the slurry;

heating the preform to a temperature above the boiling point of the solvent and below the boiling point of the matrix binder to evaporate the solvent; and

the evaporated solvent was drained off.

6. The method of claim 5, wherein

The solvent is isopropanol or acetone;

the matrix binder is an aluminum silicate or silane, and

the solid particles are of an oxide ceramic material.

7. The method of claim 6, wherein the solid particles have a size distribution in the range of 1 to 1000 nanometers.

8. The method of claim 7, wherein the slurry has between 50% to 85% by weight solid particles and between 15% to 50% by weight solvent.

9. The method of claim 8, wherein the slurry has between 75% and 81% by weight solid particles and between 19% and 25% by weight solvent.

10. The method of claim 8, wherein the oxide ceramic material is selected from the group consisting of alumina, zirconia, and yttria-stabilized zirconia.

11. The method of claim 1, comprising:

curing the slurry after achieving the desired characteristics; and

sintering the preform.

12. The method of claim 5, wherein

The solvent is water;

the matrix binder is an aluminum silicate or a silane, and

the solid particles are silica.

13. The method of claim 12, wherein the solid particles have a size distribution in a range of 1 nanometer to 1000 nanometers.

14. The method of claim 13, wherein the slurry has between 50% and 85% by weight solid particles and between 15% and 50% by weight solvent.

15. The method of claim 14, wherein the slurry has between 75% and 81% by weight solid particles and between 19% and 25% by weight solvent.

16. The method of claim 12, wherein the solid particles are colloidal silica.

17. The method of claim 12, comprising:

curing the slurry after achieving the desired characteristics; and

sintering the preform.

18. The method of claim 1, wherein the solid particles have a size distribution in a range of 1 nanometer to 1000 nanometers.

19. The method of claim 1, wherein the slurry has between 50% to 85% by weight solid particles and between 15% to 50% by weight solvent.

20. The method of claim 19, wherein the slurry has between 55% to 85% by weight solid particles and between 15% to 45% by weight solvent.

21. The method of claim 20, wherein the slurry has between 75% and 81% by weight solid particles and between 19% and 25% by weight solvent.

1. Field of the invention

The present disclosure relates to a method of making a ceramic matrix composite. In particular, the present disclosure relates to impregnating (impregnation) a matrix material into a preform of a composite material.

2. Correlation technique

Ceramic Matrix Composites (CMCs) are a subclass of composites and also of ceramics. CMC embeds ceramic fibers in a ceramic matrix to form a ceramic fiber reinforced ceramic material. The matrix and fibers may comprise any ceramic material or carbon and carbon fibers.

Oxide ceramic materials fall into two categories: monolithic (monolithic) oxide ceramics and oxide Ceramic Matrix Composites (CMC). Monolithic oxide ceramic materials comprise pure oxide ceramic powders that have not been hot pressed and sintered at temperatures in excess of 1600 ℃. The oxide CMC comprises an oxide ceramic matrix reinforced with oxide ceramic fibers. The oxide fibers have improved mechanical properties over monolithic fibers. Due to the fiber-reinforced elaboration, oxide CMCs are typically prepared using a liquid slurry that is either coated onto the oxide fibers/fabric (e.g., pre-impregnated ("pre-preg")) or liquid impregnated into the oxide fiber preform (e.g., sol-gel process).

Carbon (C), silicon carbide (SiC), aluminum oxide (Al)₂O₃) And mullite (Al)₂O₃-SiO₂) Fibers are commonly used for CMC. The particles (called "whiskers" or "platelets") are embedded in a matrix. The matrix materials include C, SiC, alumina, and mullite.

The manufacturing process generally consists of the following three steps: (1) laying up (lay-up) and fixing the fibres into a preform of the desired shape; (2) impregnating a matrix material; and (3) final machining and, if necessary, further treatment such as coating or impregnation to reduce porosity.

Most oxide CMCs are two-dimensional (2D) multilayer stacks. This is typically accomplished by pre-soaking the dry fabric with a solvated alumina matrix slurry containing a binder. That is, the slurry comprises a solvent, a matrix binder, and particles. The matrix is thermosetting and only partially cured for ease of handling during subsequent processing. The pre-preg oxide CMC will then be subjected to a temperature that will fully cure the matrix material.

Plies for the oxide CMC composite are then cut from the prepreg fabric and laid up in a vacuum bag (for autoclave processing) or press processing for compaction. Once this is done, the oven curing and sintering process steps are performed to complete the process. Where additional densification is required, vacuum infiltration is typically performed using various dilute slurries containing 20 to 60 percent (weight fraction) solids to improve infiltration by the hardening oxide CMC.

Another common processing method is to lay up a stack of dried 2D plies or three-dimensional (3D) preforms and impregnate with an alumina slurry. In this process, the dried plies are stacked between two tool plates (press plates) and impregnated in a slurry bath of an oxide slurry formulation having a high solids content (typically 75% or more weight fraction solids). Followed by a curing step and a sintering step. The oxide CMC is then hardened and "free standing", which means that it no longer needs to be placed in the tool.

The cured/sintered "free-standing" oxide CMC may be re-impregnated by additionally (one or more times) immersing the oxide CMC in a slurry bath having an oxide slurry formulation with a low weight fraction of oxide solids. Followed by a curing step and sintering. The re-infiltration and curing/sintering steps are then repeated with the more dilute slurry (to increase infiltration) until the desired density and porosity are achieved.

Oxide CMCs using these methods are time consuming and can be difficult to implement in composites with complex geometries. There are several significant difficulties with the 2D alumina prepreg process. These difficulties include:

since oxide prepregs generally have poor drape and often poor flow characteristics (due to impregnated submicron particles), laying up complex shapes with oxide CMC prepregs is challenging.

It is difficult to form plies around sharp radii or sharp edges without causing wrinkles or other anomalies in the plies, especially if off-axis plies are used.

The ply package for complex parts may be quite large (many plies of different sizes and configurations), especially where off-axis plies are used. This can make assembly time consuming and can lead to human lay-up errors.

Ply lay-up, vacuum bagging, and autoclave cycles can be slow and labor intensive.

In addition, slurry impregnation also has difficulties, including:

additional slurry infiltration can "close" the outer surface and make the internal porosity of the CMC inaccessible. That is, during subsequent processing cycles, the slurry particles may not infiltrate into the center of the CMC pores. The outer surface of the CMC may become dense, have a low porosity, and prevent the matrix from penetrating into the CMC center, which still has porous regions. Other processing steps, such as machining, may be required in order to make the interior porous region accessible.

Additional slurry impregnation in the bath may result in the matrix building up in undesired locations, requiring final machining to maintain dimensional tolerances of the oxide CMC.

Disclosure of Invention

The present disclosure describes a method of making a ceramic matrix composite material comprising impregnating a woven preform with a slurry having a solvent, a matrix binder, and particles. At least some of the solvent is removed without curing the matrix binder. The infiltration and solvent removal are repeated until the desired characteristics of the preform are obtained. The desired property is typically at least one selected from the group consisting of density, porosity, and fiber volume fraction. After the desired properties are obtained, the slurry is cured and the preform is sintered.

In one embodiment, at least some of the solvent is removed by utilizing a difference in chemical or physical properties (such as, but not limited to, boiling point temperature or vapor pressure) between the solvent and the matrix binder.

In one embodiment, the preform is heated to a temperature above the boiling point of the solvent and below the boiling point of the matrix binder to evaporate the solvent, which then impregnates the preform with the slurry, and the evaporated solvent is drained. In a particular embodiment, the solvent is isopropanol or acetone, the matrix binder is aluminum silicate or silane, and the solid particles are oxide ceramic materials.

In certain embodiments, it is contemplated that the solvent combined with the matrix binder may be water and the particles may be silica. More specifically, in certain embodiments, the particles may be colloidal silica.

In some embodiments, the solid particles have a size distribution in the range of 1 nanometer to 1000 nanometers. In some embodiments, the slurry has between 50% to 85% by weight of solid particles and between 15% to 50% by weight of solvent. Specifically, in some embodiments, the slurry has between 75% to 81% by weight of solid particles and between 19% to 25% by weight of solvent.

In some embodiments, the oxide ceramic material is selected from the group consisting of alumina, zirconia, and yttria-stabilized zirconia (yttria-stabilized zirconia).

Drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The accompanying drawings, which are presented herein to illustrate various embodiments of the invention, together with the description, serve to explain the principles of the invention. In the drawings:

fig. 1 shows a general system configuration for densifying a CMC by slurry infiltration.

FIG. 2 is a flow chart of an embodiment of the disclosed method; and

fig. 3 illustrates various types of 3D fiber architectures.

Detailed Description

The term "comprising" in the present disclosure may mean "including" or "includes" or may have a meaning commonly given to the term "comprising" in U.S. patent law. The term "consisting essentially of … … (consensurably of) has the meaning that is given to them by the united states patent law if used in the claims. Other aspects of the invention will be described in or be apparent from (and within the scope of) the following disclosure.

In the following description, the terms "thread", "fiber", "tow" and "yarn" are used interchangeably. As used herein, "thread," "fiber," "tow," and "yarn" may refer to monofilament, multifilament yarn, twisted yarn, multifilament tow, textured yarn, braided tow, covered yarn (coated yarn), bicomponent yarn, and yarn made from stretch broken fibers of any material known to those of ordinary skill in the art. The yarns may be made of carbon, nylon, rayon, fiberglass, cotton, ceramic, aramid, polyester, metal, polyvinyl glass, and/or other materials having desired physical, thermal, chemical, or other properties.

"slurry" refers to a dispersion of solids (e.g., particles such as ceramic particles) in a liquid carrier (solvent), which may also contain additives such as binders, surfactants, dispersants, and the like.

"CMC" refers to ceramic matrix composites. A sub-category of CMCs includes "oxide CMCs.

For a better understanding of the invention, its advantages and objects obtained by its use, reference is made to the accompanying descriptive matter, in which there is illustrated non-limiting embodiments of the invention in the accompanying drawings, and in which corresponding components are identified by the same reference numerals.

The present disclosure relates to a method for producing ceramic matrix composites by slurry infiltration of a preform, such as a 2D woven (woven) laminate layup (layup), a pin (pin) guided fiber lay-up produced preform, a 3D woven preform, or a woven (woven) preform in a preform/mold tool (also interchangeably referred to as "tool" and "injection tool") (hereinafter, the fiber preform type is included in the terms "preform" or "fiber preform"). The method of the present invention is characterized by removing the slurry solvent from the injection tool without completely curing or setting the binder.

The method of the present invention exploits or utilizes the difference in chemical or physical properties between the solvent and the binder. Utilizing the property differences, the process of removing the solvent without fully curing the binder can better control the density, porosity, and fiber volume fraction of the resulting CMC. The uncured binder may cause the particles/binder to flow in the mold, allowing manipulation of design elements, for example, the final CMC design elements such as density, porosity, and fiber volume fraction.

Impregnation with water

In some embodiments, the injection slurry used in the process comprises a slurry comprising alumina particles or yttria-stabilized zirconia (YSZ or ZrO)₂) An oxide ceramic material, a matrix binder ("binder"), and a solvent. The particles in the slurry are typically submicron abrasive particles having a size distribution of 1 nm to 1000 nm. In one embodiment, the particles may be silica, and in a particular embodiment, the particles may be colloidal silica particles. The slurry may have 50% to 85% (weight fraction) solids, and 15% to 50% (weight fraction) solvent. Slurries having 55% to 85% (weight fraction) solids and 15% to 45% (weight fraction) solvent are more time efficient than slurries using 50% to 54% solids. It is contemplated that a slurry having 60% to 75% (weight fraction) solids and 25% to 40% (weight fraction) solvent may be used. In particular embodiments, the alumina slurry has 75% to 81% (weight fraction) solids and 19% to 25% (weight fraction) solvent.

The binder used may be aluminum silicate, silane or other common matrix binders. The solvent used is a highly volatile solvent such as isopropyl alcohol (IPA), acetone, and the like. By "highly volatile" is meant more volatile than the matrix binder. In some embodiments, the solvent may be water.

Thus, CMC comprises three components: (1) a solvent, (2) a matrix binder, and (3) particles. The CMC includes any combination of these three components. For example, the solvent may be any one of isopropyl alcohol, acetone, or water; substrateThe binder may be any of aluminum silicate, silane, or other common matrix binders; and the particles may be alumina-containing particles or yttria-stabilized zirconia (YSZ or ZrO)₂) Or may be silica (including colloidal silica). Each of these components may be characterized as described above.

Fiber preform

A 2D woven dry fiber (or prepreg) stack, a three dimensional (3D) woven preform, a preform produced by pin guided fiber placement, a braided preform, or other preform may be fabricated from alumina fibers. The 2D architecture may have a laminate structural ply lay-up arrangement (schedule) including 0 °/90 °, 0 °/45 °/90 °/45 °, or any combination thereof. The "0 °/90 °" lay-up arrangement means: in successive layers, warp fibers (warp fibers) alternate between 0 ° and 90 ° with respect to an arbitrary reference. The "0 °/45 °/90 °/45 °" lay-up arrangement provides the angle of the warp fibers relative to an arbitrary reference in the continuous layer. Similarly, 0 °/60 °/90 °/60 ° layup may be used.

In some cases, the preform is a near net shape technical article. That is, the preform is very close to the desired final (net) shape, which may reduce the need for surface finishing, machining or grinding and/or reduce waste. Moreover, the processing time can be shortened.

The 3D fiber architecture may be orthogonal 310, ply-to-ply 320, or angle-interlocked 330, as shown in fig. 3. The fiber volume in the warp and weft directions (fill) can vary depending on the application. For example, the alumina fibers can be anyFiber grade, and any denier or other similar fiber.

Tool and apparatus

Fig. 1 shows a simplified diagram of a matrix infiltration system that can be used to practice the method of the present invention to prepare oxide CMC. The system comprises a matrix inlet 105 for providing a matrix slurry and a matrix outlet 110 for removing the matrix slurry, in particular a solvent for the slurry, from the preform (not shown). The preform is arranged in a cavity of the injection tool 115, the cavity having a shape complementary to the preform. The injection tool is divided into at least two parts so that the cavity can be exposed to accommodate the preform.

The components of the injection tool 115 may be held together by a press tool (tool press) having a top platen 120a and a bottom platen 120 b. The purpose of the platens 120a, 120b is to hold the components of the injection tool together against the infiltration pressure of the matrix slurry. The heater (not shown) that applies heat to the injection tool may be part of the press tool or separate therefrom.

The matrix inlet 105 includes a column injector 125 to provide a matrix slurry under positive pressure through tubing 130 to one or more inlets 135 of the injection tool 115. A valve 160 may be provided to prevent flow into the preform when solvent is removed during densification of the preform. The substrate outlet 110 includes a vacuum pump 150 to provide negative pressure to one or more outlets 140 of the injection tool 115 through a substrate trap (trap)145 and a tube 155.

The combination of the positive pressure applied to the matrix slurry at the one or more inlets 135 and the negative pressure applied at the one or more outlets 140 helps to evenly distribute the matrix slurry throughout the preform during infiltration. The matrix trap 145 can capture excess slurry exiting the one or more outlets 140 during slurry impregnation. The negative pressure applied to the one or more outlets 140 may also drain the solvent used to densify the preform.

In use, the valve 160 is opened, thereby enabling the matrix slurry to be provided from the column injector to the preform in the injection tool under positive pressure. Negative pressure may be applied by a vacuum pump to assist in the removal of the matrix slurry from the entire preform. The slurry leaving the injection tool may indicate that the slurry has infiltrated the preform. Excess slurry leaving the injection tool can be captured by the trap.

Valve 160 may be closed during densification of the preform. During this part of the process, the solvent is separated from the matrix slurry by the negative pressure applied to the one or more outlets and expelled from the injection tool. The solid oxide particles and binder in the slurry remain in the interstices of the preform, making the preform denser.

Process for the preparation of a catalyst

Fig. 2 shows a flow diagram 200 of a method of making oxide CMC in accordance with the present disclosure. The 2D woven laminate layup, the 3D woven preform, the preform produced by pin guided fiber placement, the woven preform or other preforms (commonly referred to as "preforms") are prepared (210) according to techniques known to those of ordinary skill.

In step 220, the preform is placed in an injection tool, such as a resin transfer mold tool, and the injection tool is then loaded into an injection tool press 230, which applies pressure to the injection tool to hold the tools together during subsequent application of pressure to the tools.

In steps 240, 242, 244, 246, 248 and 250, a first slurry infiltration is performed on the injection tool and the preform in the press. In step 240, the slurry is injected under positive pressure into the inlet of the injection tool and into the preform within the tool. Negative or vacuum pressure (242) may be applied to help disperse the slurry evenly throughout the preform.

In a particular embodiment, the slurry is an IPA solvated mixture comprising submicron-sized alumina particles and a silane binder. For example, the preform may be an aircraft antenna window housing having nominal dimensions of 8.56 "x 0.938" (21.7cm x 2.4 cm). The slurry may be injected into the injection tool at a flow rate of about 50cc/min at a pressure of 200-. In addition to the aircraft antenna window skin examples described above, oxide CMCs may also be used in other applications, including turbine exhaust structures, radomes, missiles, satellites, and other high temperature environment applications.

The pressure of the slurry on the injection tool is then released and heat is applied to the slurry in the preform by heating the injection mold tool (244). When the slurry reaches a predetermined temperature, the solvent removal step 246 is initiated to expel solvent from the preform. A vacuum pump may be used to apply a negative pressure at the outlet of the injection tool to assist in the removal of the solvent. After the solvent is removed, the heat is removed and the injection tool is allowed to cool in step 248. Removal of the solvent from the slurry leaves solid oxide particles of the slurry in the interstices of the preform, thereby making the preform denser.

By taking advantage of the different physical properties between the solvent and the binder, the solvent can be removed without fully curing the matrix binder. Differences in physical properties include different boiling points, phase diagrams, vapor pressure equations and curves, reactivity, and the like. That is, the adhesive is "B-staged". "B-staging" is a process that removes at least some of the solvent from the adhesive, allowing the structure to be staged (meaning a solid that is only partially cured).

In particular embodiments, a boiling point temperature difference between the solvent and the matrix binder may be used to vaporize the solvent but avoid curing the matrix binder. In one example, the slurry is an IPA solvated mixture comprising submicron-sized alumina particles and a silane binder. In this example, heat was applied at atmospheric pressure to raise the temperature of the slurry to 180 ° F (82.5 ℃) the boiling point of the IPA solvent, which is 250 ° F (121.1 ℃) below the cure temperature of the silane adhesive. Thus, raising the temperature of the slurry to about 180 ° F (82.5 ℃) will cause the IPA solvent to vaporize or evaporate without curing the silane-based binder. Vacuum suction pressure (suction pressure) may be applied to the injection tool to expel the evaporated solvent. For example, an inhalation pressure of 20inHg (508mmHg) may be used.

Removal of the solvent creates free/open pores in the preform. That is, an open volume is formed in the preform by removing solvent from the binder in the preform. For example, if the slurry is 80% solids and 20% solvent by weight, then the removed solvent will cause some porosity to remain in the preform.

In step 250, it is determined whether the oxide CMC has a desired density, porosity, and/or fiber volume fraction. If the oxide CMC does not have the desired density, porosity, and/or fiber volume fraction, a second slurry infiltration may be performed as in step 240-250 with the same or a different slurry formulation.

In the second infiltration, the open volume formed in the preform as a result of the first solvent removal is filled with the slurry. The solvent is then removed for a second impregnation, thereby creating free/open pores for additional impregnation (if needed). This process is repeated until the desired CMC density, porosity, and/or fiber volume fraction is achieved.

In a particular embodiment, the same slurry formulation as the first impregnation is used. In this embodiment, no dilution or alternative slurry formulation is required. As in the embodiments described above, the slurry may be injected into the injection mold at a flow rate of about 50cc/min at a pressure of 200-. The volume of slurry in the second impregnation is typically less than the volume of slurry in the first impregnation.

After infiltration is complete, the injection tool and preform are heated to a temperature to cure 252 the matrix binder in the preform. After the matrix binder is cured, heat is removed from the injection tool in step 254 and the tool is allowed to cool. The injection tool is removed from the press 256. The CMC is then demolded (i.e., removed from the injection tool) (258) and sintered (260). Typical sintering temperatures are 1000 ℃ to 1200 ℃.

Other embodiments are within the scope of the following claims.

The claims (modification according to treaty clause 19)

1. A method of making a ceramic matrix composite comprising:

impregnating the preform with a slurry having a solvent, a matrix binder, and solid particles;

removing at least some of the solvent without curing the matrix binder; and

repeating the infiltrating and removing the solvent until desired characteristics of the preform are obtained,

wherein the desired characteristic is at least one selected from the group consisting of density, porosity, and fiber volume fraction.

2. The method of claim 1, wherein the removing at least some of the solvent comprises utilizing a difference in chemical or physical properties between the solvent and the matrix binder.

3. The method of claim 2, wherein the chemical or physical property is boiling point temperature.

4. The method of claim 2, wherein the chemical or physical property is vapor pressure.

5. The method of claim 3, comprising:

infiltrating the preform with the slurry;

heating the preform to a temperature above the boiling point of the solvent and below the boiling point of the matrix binder to evaporate the solvent; and

the evaporated solvent was drained off.

6. The method of claim 5, wherein

The solvent is isopropanol or acetone;

the matrix binder is an aluminum silicate or silane, and

the solid particles are of an oxide ceramic material.

7. The method of claim 6, wherein the solid particles have a size distribution in the range of 1 to 1000 nanometers.

8. The method of claim 7, wherein the slurry has between 50% to 85% by weight solid particles and between 15% to 50% by weight solvent.

9. The method of claim 8, wherein the slurry has between 75% and 81% by weight solid particles and between 19% and 25% by weight solvent.

10. The method of claim 8, wherein the oxide ceramic material is selected from the group consisting of alumina, zirconia, and yttria-stabilized zirconia.

11. The method of claim 1, comprising:

curing the slurry after achieving the desired characteristics; and

sintering the preform.

12. The method of claim 5, wherein

The solvent is water;

the matrix binder is an aluminum silicate or a silane, and

the solid particles are silica.

13. The method of claim 12, wherein the solid particles have a size distribution in a range of 1 nanometer to 1000 nanometers.

14. The method of claim 13, wherein the slurry has between 50% and 85% by weight solid particles and between 15% and 50% by weight solvent.

15. The method of claim 14, wherein the slurry has between 75% and 81% by weight solid particles and between 19% and 25% by weight solvent.

16. The method of claim 12, wherein the solid particles are colloidal silica.

17. The method of claim 12, comprising:

curing the slurry after achieving the desired characteristics; and

sintering the preform.

18. The method of claim 1, wherein the solid particles have a size distribution in a range of 1 nanometer to 1000 nanometers.

19. The method of claim 1, wherein the slurry has between 50% to 85% by weight solid particles and between 15% to 50% by weight solvent.

20. The method of claim 19, wherein the slurry has between 55% to 85% by weight solid particles and between 15% to 45% by weight solvent.

21. The method of claim 20, wherein the slurry has between 75% and 81% by weight solid particles and between 19% and 25% by weight solvent.

22. The method of claim 1, wherein the type of preform is selected from the group consisting of a two-dimensional (2D) dry fiber (or prepreg) layup, a 2D woven laminate layup, a pin-guided fiber placement resulting preform, a three-dimensional (3D) woven preform, and a braided preform.