WO2019179700A1

WO2019179700A1 - Moulded part and method for producing a moulded part

Info

Publication number: WO2019179700A1
Application number: PCT/EP2019/053758
Authority: WO
Inventors: Stefan Lampenscherf; Gia Khanh Pham
Original assignee: Siemens Aktiengesellschaft
Priority date: 2018-03-23
Filing date: 2019-02-15
Publication date: 2019-09-26
Also published as: DE102018204467A1

Abstract

The invention relates to a moulded part, in particular a moulded part produced from a fibre-reinforced ceramic material, such as a turbine component, burner component and/or a component of an exhaust gas system. In terms of the fibre-reinforced ceramic material, the focus is on ceramic matrix composites, CMC. The invention also relates to a method for producing a three-dimensional moulded part from two-dimensional reagents, such as prepreg CMC layers and/or prepreg CMC tapes, via corresponding lay ups. With the invention, an option for the automated processing of prepreg CNC layers and/or prepreg CMC tapes and/or a prepreg CMC continuous tape has been created for the first time, given that a flat prepreg CMC material is provided having an extension and weight that is defined and which changes predictably during the processing in the lay up method. This is achieved in that, instead of the usual addition of solvent and/or water to the slurry, a dispersing agent is used, with which the mineral powder is coated before the production of the slurry, and which restricts or prevents an agglomeration and thereby enables the desired viscosity of the slurry, even with little or no water and/or solvent.

Description

description

Molded part, method for producing a molded part

The invention relates to a molded part, in particular a made of egg nem fiber-reinforced ceramic material form part such as a turbine component, Brennerkom component and / or a component of an exhaust line. Fiber-reinforced ceramic material focuses on the Ceramic Matrix Composites, CMC. Furthermore, the invention relates to a method for producing a three-dimensional molded part from two-dimensional educts, such as prepreg CMC layers and / or prepreg CMC strips, by means of corresponding lay-ups.

Ceramic matrix composites, CMCs, such as oxidi cal CMCs or CMCs based on silicon carbide, show very good thermo-mechanical properties at high temperatures and temperatures for the production of moldings for turbines, especially hot gas turbines and / or for the production of moldings of a burner, a Exhaust line can be profitably used. In particular, oxide-based CMC moldings heat resistant, thermoshock and oxidation resistant dig.

For example, oxidic CMCs are composed of an oxide-ceramic fiber fabric, such as, for example, a fabric of Al ₂ O ₃ and / or mullite fiber in an oxide-ceramic bedding matrix. The matrix material, also called slip, comprises - during processing on an aqueous and / or solvent-based basis - a polymer and dissolved therein mineral, in particular oxide ceramic powder. The CMC is two-dimensional, as a layer or strip, for processing in the form of the so-called prepreg. For the preparation of the prepreg, it is essential that the powder has a low viscosity, so that the slurry can flow through the fibers in order to wet all fibers as evenly as possible and at the same time a sufficiently high viscosity, due to the high solids content in the slurry, so that a prepreg is formed in which the fibers are homogeneously embedded.

The proportion of filler and the polymer in the slurry provide the desired property profile of the three-dimensional molded article produced later from the prepreg, water and / or solvent are removed again after wetting. Last but not least, the slip needs at least superficially a good stickiness, so that it adheres to the Fa fibers.

This stickiness is generally achieved by drying the slurry during processing, removing the solvent and / or water from the slurry, and / or curing or gelling the polymer on the surface, which optionally manifests itself optically in a surface gloss and just one leads to some stickiness.

A disadvantage of the known prepregs is that such prepreg CMC layers or prepreg CMC tapes are not suitable for automated processing, because the changes in volume and the changes in surface finish are simply too little predictable for an automated processing process and too strong change on a case-by-case basis. Therefore, it has hitherto been in the production of CMC moldings on a manual processing by hündisches depositing the pre-qualified prepreg CMC layers and / or prepreg CMC tapes with all those known for non-automated processes and therefore not further elaborated at this point Disadvantages indicated.

The object of the present invention is therefore to provide a mold part of a CMC, in particular of an oxide or silicon carbide-based fiber composite ceramic, which can be produced in a automated manner and furthermore to provide a process by which prepreg CMC resins are used. Layers and / or prepreg CMC tapes both on oxidic and silicon carbide based automated or at least partially wise automated three-dimensional moldings can be produced.

This object is achieved by the subject matter of the invention, as described in the description and claims, ge triggers.

The subject of the present invention is therefore a molded article obtainable by processing one or more prepreg CMC tapes and / or one or more prepreg CMC layers comprising ceramic fibers surrounded by slurry, the slurry being composed of a mineral powder, which in is a polymer dispersed, and the slurry has a Vis viscosity, on the one hand low enough so that the Fa fibers are wetted by the slip and on the other hand high enough that the prepreg CMC layer or the prepreg CMC tape ver workable is, wherein in the slurry for a dispersant is provided which aggravates the agglomeration of mineral powder ver particles and thus ensures the viscosity. In addition, the subject matter of the invention is a process for the production of a three-dimensional CMC molded article comprising the following process steps:

Coating of a mineral powder with a dispersing agent,

Preparing a slurry of the coated mineral powder,

Use of the slip to make a prepreg CMC tape or prepreg CMC sheet,

Lay-up of the prepreg CMC tape or the prepreg CMC layer for the construction of a prepreg CMC molding

- Dry,

- compacting and

Sintering the prepreg CMC molding to a CMC molding.

Slip for producing prepreg CMC layers and / or prepreg CMC strips is conventionally prepared by aqueous or solvent-containing suspension / dispersion of a powder, for example by grinding epoxy resin with Nutrient powder in aqueous slurry. General knowledge of the invention is that it is possible to dispense with a solvent and / or water, if for the Schli cker a mineral powder is used, the powder particles are protected against agglomeration.

This protection is achieved, for example, by superficial activation of the mineral powder and is preferably carried out by a dispersing agent. In this case, it is particularly preferable to use a dispersant which has hydrogen-acidic functional groups which attach to the generally oxygen-rich surface of, for example, metal oxide powder particles. So it comes to egg ner at least partial surface coating of Parti angle. The thickness of the surface coating is in the molecular kularen area, in particular in the monomolecular region, since the chemical structure of the dispersant is preferably designed so ge that it binds, for example steric reasons, a further addition of Dispersiermittelmolekülen.

The coated particles repel each other accordingly, so that a high viscosity of the polymer powder mixture can also be adjusted without addition of solvent and / or aqueous slurry.

As a result, it is generally possible to dispense entirely or partially with the addition of these or other leveling agents, such as organic solvents, alcohols, etc., and / or water for the production of the slip.

A solvent and / or low-water or even Lösungsmit tel- and / or anhydrous slip is particularly advantageous because it undergoes less Volu menänderung and / or shrinkage by drying out the What sers respectively the solvent during processing. This causes changes in the volume of the CMC prepreg during processing to be less drastic and the calculable Increases in the changes of a resulting prepreg CMC layer and / or a prepreg CMC tape during processing increases.

Thus, a prepared according to the invention prepreg CMC layer and / or prepared according to the invention prepreg CMC tape with dispersant also processed in an automated and / or continuously running process who the. Most or all of the manual intermediate steps can then be dispensed with, resulting in quality improvements, reproducibility improvements and / or cost savings in the manufacturing process for a CMC molded part.

For example, this makes it possible to process prepreg CMC layers and / or prepreg CMC strips in an automated lay-up process, such as the "Fiber Patch Placement" process FPP process.

With the Fiber Patch Placement FPP technology, complex and large molded parts made of fiber reinforced plastic material, such as carbon fiber plastics - CFRP - are already partially or fully automated in the automotive and / or aircraft industry. This process can also be applied to prepreg CMC sheets and prepreg CMC tapes made in accordance with the present invention.

When manufacturing using FPP, a digital 3D component is first created using CAD-CAM software. The CAD model is used for off-line programming of a lay-up robot. For the lay-up process then pre ferred bands, for example, endless prepreg CMC tapes having a width of 1 cm to 3 cm, in particular from 1 cm to 2 cm used.

Prepreg CMC tapes comprise ceramic fibers infiltrated with Schli cker. These are, for example, fibers of silicon carbide and / or metal oxide ceramic fibers, such as, for example, of aluminum dioxide and / or from mullite, a silicate known under this trivial name, as well as from any mixtures of aluminum dioxide and mulitit between themselves and with other metal oxides or metal oxide mixtures. A ceramic fiber for an oxidic CMC regularly has more aluminum dioxide than mullite, for example in a ratio of 70 to 99.999% by weight of Al 2 O 3, preferably 80 to 90% by weight, particularly preferably 85% by weight of Al 2 O 3 with 30 to 0.001% by weight, preferably 10 to 20% by weight. , in particular 15% by weight of mullite. For example, ceramic fibers of the company 3M are set, which under the trade name Nextel®, in particular

Nextel® 610 and / or Nextel® 720 are known.

The fibers can be present in any combination. As a rule, to form the prepreg fibers in the form of fiber composites, so braided fibers, fiber fabrics and / or tissues submitted, which then trated infiltrated with the slurry and / or impregnated. The pre-infiltrated with the Matrixschli cker or impregnated fiber fabric is the prepreg.

The matrix slip comprises, on the one hand, the mineral powder, a dispersant and, on the other hand, a polymeric binder, for example a resin, in particular a thermoset or a thermoplastic.

As a thermoset example, epoxy resin and / or acrylic resin is used to prepare the slip.

As a thermoplastic, for example, high-density polyethylene - HDPE -, polypropylene - PP -, polyamide - PA - for example in the form of PA 6, PA 12, PA 66, polyphenylene sulfide - PPS -, polyphthalamide - PPA -, polyethyleneimine - PEI -, polyether ketone ketone - PEKK and / or polyetheretherketone PEEK - and any mixtures and / or blends of the aforementioned thermoplastics used.

The polymer makes up the main part in the solvent- and water-free Schli cker and is more than 50% by mass and / or more than 45% by volume, in particular more than 70% by mass and more than 50% by volume.

According to an advantageous embodiment of the invention, the particles of the mineral powder are superficially treated, in particular coated with the dispersant. The particle size of the particles in the mineral powder can vary, because several particle fractions can be present.

The mineral powder is preferably present in the slurry in a high volume fraction, as this achieves the excellent mechanical properties of the CMC molding. A slurry with a high solids content, as it is desireable in the present case, for example, has a solids content of greater than 40% by volume.

The individual particle fractions of the mineral powder may differ in material, shape and size.

For example, oxide powders such as alumina, molybdenum, zirconium oxide, and / or yttrium-stabilized zirconium oxide-YSZ-, yttrium-aluminum-garnet-YAG-, and / or yttrium oxide are present in the mineral powder for an oxidic CMC and any Mixtures of the abovementioned metalloxy compounds.

For example, there are at least two particle fractions with respect to the particle size in the mineral powder, one of which is a coarser particle fraction and another a finer particle fraction. The preferred particle fractions are in the range of 100 nm to 10 ym.

When several particle fractions of different sizes are present, the coarser particle fraction usually predominates. In particular, mixing ratios of 50:50 coarse to fine up to 80:20 coarse to fine in parts by mass, may be useful. Possibly the coarse particle fraction and / or the fine particle fraction even as a mixture of several particle fractions before.

The particle size of the powder particles of the mineral powder in the slip powder in terms of mean particle size d50 be contributes to a here as a "coarser" fraction called powder fraction at some ym, for example, 0.4 to 3.5 ym, especially at 0.5 to For the finer fraction, the value is correspondingly lower, for example less than 0.3 μm, in particular between 0.05 and 0.3 μm, in particular between 0.1 μm and 0.3 μm.

For example, mixtures of d50 = 0.5 ym for the coarser particle fraction and d50 = 0.15 ym for the finer particle fraction can be used here.

For example, surface-active substances such as surfactants are used as dispersants, in particular ammonium salts of organic acids, in particular carboxylic acids, such as for example the alkylolammonium salt of a copolymer having acidic groups. Particularly advantageous are long polymers which attach to the surface of the mineral particles and prevent there the addition of further molecules by steric hindrance. Such a long polymer is also commercially available under the name Disperbyk®. In the solvent and / or water-free slip, the dispersant is present in an amount of less than 10%, in particular less than 6% by weight, more preferably in an amount of 4%.

After providing the slurry, fiber webs or fiber bundles are infiltrated with the slurry and / or imprinted. The prepreg CMC tapes are processed for processing, in particular also for automated processing, to a predefined width and are not dried, dried, cured or hardened as required. This is different depending on the slip, in particular depending on the polymer used, different. For the automated construction of the three-dimensional molded part, a robot is preferably used, which carries out an automated lay-up of the prepreg CMC strips or the prepreg CMC endless strip stepwise in a metallic mold. Depending on requirements, an intermediate lamination can be carried out with or without pressure.

In an exemplary automated FPP process, a lay-up robot will lay the pre-assembled prepreg CMC tape, CMC endless belt or ribbons in or on a forming tool according to the CAD model and cut to a defined length. In a prepreg CMC tape with a Durop loads, such as epoxy resin, may be useful for a Zwischenlamination under mechanical pressure after hanging under certain circumstances, because a prepreg CMC tape with thermoset at the time not yet cured so sticky yet , is moist and laminatable. On the other hand, a prepreg CMC tape with a thermoplastic, if already cured, can be remelted by heat and then laminated in a viscous state. Thus, a three-dimensional molded part can be built up additively and stepwise.

A prepreg CMC tape of prefabricated width is the prerequisite, for example, for the use of the Fiber Patch Placement FPP technology for the automated production of components made of fiber composite ceramics. With this technology, complex molded parts made of CMC can be mass-produced, with low costs, low rejection rates and constant quality.

After the lay-up process, the three-dimensional prepreg CMC molded part is post-tempered, compacted and compressed in a drying oven, under pressure, as required, and the polymer is permanently cross-linked or cured. The after-treatment after the lay-up process of the three-dimensional prepreg CMC laminates takes place analogously to the manually produced with drying and sintering.

An exemplary composition for an embodiment of a slurry according to the invention is given below.

It will be about

45% by volume or about 25% by weight of an A1203 powder mixture with a coarse and a fine powder fraction in a coarse to fine ratio of

50:50 to 80:20 submitted.

The coarse fraction is a commercial A ^ Cg powder with d50 = about 0.5ym, for example that with the trade name CT 3000SG® from Almatis Corp.

The fine fraction is a commercial A ^ Cg powder with d50 = 0.15ym, for example that with the trade name TM-DAR® Taimei.

This powder mixture is coated with 4% by mass dispersing agent and dispersed in epoxy resin. The finished slurry is used for infiltration of a fiber fabric made of alumina fiber, for example Nextel® 610 from 3M. From the thus prepared prepreg CMC tape is an automatically ver workable prepreg CMC tape of prefabricated width, for example, with a width between 1 and 2 cm, cut out.

The invention will provide for the first time a possibility for the automated processing of prepreg CMC layers and / or prepreg CMC strips and / or a prepreg CMC endless strip, since a planar prepreg CMC provides material for disposal whose dimensions and weight are defined and predictably changed during processing in the lay-up process. This is achieved in that instead of the usual solvent and / or water addition to

Schlicker here a dispersant is used with the the mineral powder is coated prior to the production of the slip and that restricts or prevents agglomeration and thus makes the desired viscosity of the slip possible with little or no water and / or solvent.

Claims

claims

A molding obtainable by processing one or more prepreg CMC ribbons and / or one or more prepreg CMC sheets comprising ceramic fibers surrounded by slip, the slurry being a mineral powder dispersed in a polymer is present, and the slurry has a viscosity which is low enough on the one hand, so that the fibers are wetted by the slip and on the other hand high enough that the prepreg CMC layer or the prepreg CMC tape is processable, in the slip therefor a dispersing agent is provided which impedes agglomeration of the mineral powder particles and thus ensures the desired viscosity.

2. Molding according to claim 1, wherein the mineral powder is coated on the surface in prepreg CMC with dispersant.

3. Molding according to claim 2, wherein the superficial coating Be the mineral powder over its entire surface.

4. Molding according to one of the preceding claims, wherein the dispersant is a long-chain polymer.

5. Molding according to one of the preceding claims, wherein the dispersant is an ammonium salt.

A molding according to any one of the preceding claims which is of an oxidic CMC.

7. Molding according to one of the preceding claims, wherein the mineral powder is more than 70% by mass of aluminum oxide.

A molding according to any one of the preceding claims which comprises ceramic fibers of alumina.

9. A process for producing a CMC molding, comprising the following process steps:

Coating of a mineral powder with a dispersing agent,

Preparing a slurry of the coated mineral powder,

Use of the slip for producing a two-dimensional prepreg CMC tape and / or a prepreg CMC layer,

Lay-up of the prepreg CMC tape or the prepreg CMC layer to build a three-dimensional prepreg CMC molding

- Dry,

- compacting and

Sintering the prepreg CMC molding to a CMC molding.

10. The method of claim 9, wherein the lay-up process for building the three-dimensional prepreg CMC molding from the two-dimensional prepreg CMC tape or the two-dimensional prepreg CMC layer is automated.

11. The method according to any one of claims 9 or 10, wherein from the two-dimensional prepreg CMC tape or two-dimensional prepreg CMC layer before the lay-up process step, a prefabricated prepreg CMC tape is cut.

12. The method according to any one of claims 9 to 11, wherein the lay-up process step comprises one or more intermediate process steps of the lamination and / or the compression.