DE102008006350A1 - Method for producing a glass composite body and household appliance component - Google Patents

Abstract

The method for producing a glass composite body comprises the following steps: preparing at least one raw material mixture comprising glass powder mixed with fibers, the glass powder at least partially comprising an old glass powder; Forming the at least one raw material mixture in a mold; Heat treating the formed at least one raw material mixture to join it to a one-piece body.

Description

The The invention relates to a method for producing a glass matrix material and a home appliance component made therewith.

conventional Ceramic components require tools for their manufacture, which sufficiently pre-compact the starting material. The ensuing Process of material consolidation requires long process times and high temperatures.

Out DE 19 25 009 B2 are a fiber reinforced composite consisting of carbon fiber reinforced glass and its use. The composite may be made by mixing together carbon fibers and pulverized glass, pressing the mixture, and then sintering. For pressing cold or hot pressing can be used. The glass used is a type of glass chosen specifically for its properties.

Out DE 44 16 489 C1 discloses a method for producing decorative natural stone-like plate-shaped building and decorative materials and materials produced therefrom for cladding façades, walls and floors indoors and outdoors from mixtures of broken glass, mineral components and finely divided additives. Old glass can be used as glass. The raw material mixture is first evened out in a mold and then dried out. This is followed by annealing of the admixture to a temperature of 720 ° C to 1100 ° C for annealing, followed by a cooling step. In this case, the mold material must be chosen so that a sintering of the mold with the mix is omitted. The flexural strength of the resulting molded article is typically between 18 and 23 N / mm ² .

EP 0 718 249 A1 discloses a glass composite of an oxide-based glass matrix in which ceramic whisker material or cut inorganic, including ceramic, fibers are embedded and which further comprises flakes of ductile metal. The glass is selected specifically for the intended use. This composite can be produced by sintering under a protective gas atmosphere (eg nitrogen, argon) or in a vacuum.

Out DE 33 18 813 C2 discloses a molding process for fiber-reinforced glass matrix or glass-ceramic matrix composite articles wherein the fibers, including SiC fibers, are configured as whiskers. The raw material of glass powder added with the fibers or whiskers is first pressed to subsequently serve as a material for an injection molding process. The fibers are designed as short-cut fibers, with the smallest fiber length depending on the smallest thickness of the wall of the part to be molded.

Out DE 37 31 649 discloses a process for the production of open-pored, predominantly made of glass ceramic sintered bodies, in which a sinterable, finely ground and crystallizable glass powder, which is mixed with inorganic salt as a pore-forming agent, together with particulate, whisker or fibrous components at 840-890 ° C. is sintered for two to three hours.

It The object of the present invention is a possibility for producing a body of an inorganic material with low-cost raw materials and compared to traditional ones Production process of simple tools and reduced energy costs to provide through lower process times and temperatures, especially for household appliances.

These Task is by means of a method according to claim 1 and a Device according to claim 15 solved. Advantageous embodiments are in particular the dependent claims removable.

• – Präparieren mindestens einer Rohmaterialmischung, welche mit Fasern versetztes Glaspulver aufweist, wobei das Glaspulver zumindest teilweise ein Altglaspulver umfasst;
• – Formen der mindestens einen Rohmaterialmischung in einem Formwerkzeug;
• – Wärmebehandeln der geformten mindestens einen Rohmaterialmischung zu ihrem Verbinden zu einem einstückigen Körper.

The method for producing a glass composite is characterized in that it comprises the following steps:

• Preparing at least one raw material mixture comprising glass powder mixed with fibers, the glass powder at least partially comprising an old glass powder;
• - forming the at least one raw material mixture in a mold;
• Heat treating the shaped at least one raw material mixture to join it to a one-piece body.

"Fibers" are generally understood to mean bodies whose extent in one dimension is considerable larger than in the other two directions. Therefore, needles or whiskers are understood as fibers here. The length and the material of the fibers is dependent, for example, on a thickness of the shaped body and its desired mechanical properties.

The The above method is based on the surprising finding that also for applications at higher temperature and with increased demands on the mechanical strength, especially in the household appliance sector, used glass as base material can be used, although there are many admixtures in unknown Quantity has. The use of old glass gives the advantage that a very reasonably priced starting material available which is with simple tools as well as at reduced energy costs is processable through lower process times and temperatures, as specifically stated below.

to Particularly inexpensive production, it is advantageous if the glass powder the raw material mixture consists entirely of used glass powder.

Prefers are ceramic and / or mineral fibers, in particular calcium silicate fibers. Especially preferred is a mass fraction of calcium silicate fibers in a glass powder-calcium silicate fiber mixture in the range of 0 to 50%, especially between 5 and 35%, more specifically between 12 and 17%.

It is particularly preferred when the fibers comprise short fibers. The Short fibers have a length of typically a few 10 microns up to just over 1 mm.

Preferably the molding step comprises pressing, more preferably, but not limited to, a pressing at a Pressing pressure of not more than 1 MPa. This is far less than usual for glass composite bodies, namely in the range between 10 MPa and 100 MPa. This reduces the device-technical effort considerably. However, one is Pressing at higher pressures also possible.

Of the Step of molding may additionally or alternatively, however also a shaking or knocking of the mold (pressing pressure = 0), thereby already sufficient compaction and strength for a subsequent heat treatment can result.

Of the Step of the heat treatment may be a joining means Sintering and / or melting.

It is preferred when the raw material mixture at a temperature between 650 and 1000 ° C, especially between 750 and 900 ° C, especially between 800 and 850 ° C, heat treated becomes.

If the temperature range of 650-1000 ° C considered is, so may run at the lower temperature limit, a process, which comes close to sintering. At higher temperatures (eg. B. around 800 ° C) has with high probability already used a melting. However, it is a "moderate melting", for example, surface structures this process survive as far as possible without damage.

Preferably, the raw material mixture is not heat treated for much longer than 1 hour, especially not longer than 75 minutes. The exact heat treatment time depends on the size and possibly also on the shape of the component. Thus, a typical heat treatment time for a cuboid shaped body with the dimensions of about 30 × 12 × 1-2 cm ³ in the range of 30 to 60 minutes, in particular in the range of 40 to 60 minutes. Smaller components, such as a burner cap with a diameter of 75 mm and a thickness of a few mm, for example, can be heat treated at 800 ° C in 15 to 20 minutes. Even smaller pellets with a diameter of about 10 mm and a thickness of a few mm in 5 to 10 minutes. For moldings with a thickness of much more than 20 mm, it may be useful to extend the heat treatment time to just over one hour. Compared with conventional glass ceramics, there is a time advantage in all cases.

to easier processing, it is advantageous if the glass powder the raw material mixture by means of a fluidizing agent, in particular by means of silicone oil, is fluidized. By the improved Flowability of the powder is in particular the Production of larger and more complex components facilitated.

• – mindestens ein metallischer Bestandteil beigemengt wird, insbesondere Metallpulver, Metallgranulate, Metall-Flakes, Metalldrahtstücke und/oder Metallfasern, und/oder
• – mindestens ein weiterer keramischer Bestandteil beigemengt wird, insbesondere weitere Keramikfasern, Keramikpulver und/oder Keramikgranulate, und/oder
• – Pigmente beigemengt werden, und/oder
• – mindestens ein weiteres anorganisches Material, insbesondere Pulver, Granulate und/oder Fasern, beigemengt wird.

For influencing certain material properties (eg bending stress, modulus of elasticity, impact strength, hardness, thermal conductivity, magnetic properties, etc.), it may be advantageous if the raw material rialmischung:

• - At least one metallic ingredient is added, in particular metal powder, metal granules, metal flakes, metal wire pieces and / or metal fibers, and / or
• - At least one further ceramic ingredient is added, in particular further ceramic fibers, ceramic powder and / or ceramic granules, and / or
• - Pigments are added, and / or
• - At least one further inorganic material, in particular powder, granules and / or fibers, is added.

It may be advantageous for adjusting a porosity, if the raw material mixture contains organic materials (eg powder and / or granules and / or fibers) or blowing agents (eg calcium carbonate) be added.

It is particularly advantageous for ease of preparation when the raw material mixture is heat-treated in the mold. Preference is given here a use of a release agent, for. As boron nitride, to the component to remove without damage from the mold.

It can be used to adjust and adjust the material properties of the heat-treated and thus solidified molded body be advantageous if at least two raw material mixtures are prepared, of which at least one raw material mixture offset with fibers Glass powder, wherein the glass powder at least partially Contains used glass powder. These raw material mixtures can in particular successively or alternately filled in the mold be, for. B. as different layers, possibly several times alternately. They are then shaped together, z. B. pressed, and heat treated, resulting in a consolidated, one-piece glass composite body with zones or areas of different material properties results.

It is particularly preferred if the finished glass composite body a household appliance component is, in particular, if this component during normal operation of the household appliance for use is provided under a temperature load.

Especially it is preferred, if the component as a burner cap, surface grill, Iron sole, top panel or gas well is designed.

A Sealing the surface of the component, for example by commercial sealers, sol-gel coatings or additional thermal treatment of the surface (eg, Beflämmen), is possible.

Across from classic glass and sintered ceramics offers the above described Material or the body made with it, among others the following advantages: through the use of used glass powder as main component result in lower material costs. Further, they become proportionate low manufacturing temperatures allows (conventional Ceramics 1250-2500 ° C). In addition, a pressing the powder at relatively low or even without pressure possible (conventional sintered ceramic between 10 and 100 MPa) and it is a relatively low heat treatment time of under reachable within an hour. The exact heat treatment time is usually dependent on the component size. Raw materials and manufacturing methods thus offer cost advantages conventional sintered ceramic.

In The following embodiments illustrate the method for producing a glass composite body and the home appliance component described in more detail schematically.

1 shows an enlarged section of a glass composite body according to a first embodiment;

2A and 2 B show a glass composite according to a second embodiment in front view or as a sectional view in side view;

3 shows a sectional side view of a glass composite body according to a third embodiment.

1 shows a glass composite body 1 from a glass or glass-ceramic matrix 2 , in the ceramic short fibers 3 are embedded. The glass ceramic matrix 2 also has pores 4 on.

The glass composite body 1 is produced by first admixing an old glass powder finely ground from waste glass with ceramic short fibers, fluidizing it with silicone oil and applying it to an inorganic blowing agent for targeted pore formation. With respect to the particle size spectrum, D50 of the individual charges is 10-20 μm in this example.

Thereafter, the powder mixture was pressed under a press pressure of in the range of not more than 1 MPa in a mold. Subsequently, the compressed mixture was left in the mold in the form of approximately 30 × 12 × 1-2 cm ³ in the mold and heat-treated at 800 ° C. for one hour.

It results in dimensionally stable, one-piece glass composite body with a glass matrix, d. h., a matrix of non-crystalline and / or a crystalline glass (glass-ceramic).

2A and 2 B show in a front view and in a sectional view along the line AB 2A a glass composite body 5 according to a second embodiment, with two different starting mixtures 6 . 7 from each waste glass powder with ceramic short fibers has been produced. Merely for the sake of clarity, here are the different material areas 6 . 7 drawn without further structuring or components. They can be formed by appropriate filling in and pressing in the mold convincing, possibly several times alternately. They are then pressed together and heat treated, resulting in a one-piece body with zones or areas 6 . 7 results in different material properties.

3 shows a glass composite body 8th according to a third embodiment with three layers in which one layer 9 made of used glass powder with ceramic short fibers between two layers 10 another material composition of glass powder is inserted with ceramic short fibers (sandwich structure). The outer layers 10 have a relatively stronger material property, while the middle layer 9 has a foamed internal structure. In one of the outer layers 10 and afterwards into a part of the middle position 9 are vent holes 11 introduced, which can serve as venting channels, for example. The ventilation holes 11 have been introduced into the body after compression, but in principle can also be introduced during compression, z. B. by a suitably shaped pressing tool. During the heat treatment step, a surface structuring, and thus also the ventilation holes, is retained. By means of the vent holes, a lifting or spalling of layers or layer parts due to a gas pressure build-up in the material during the heat treatment is avoided.

Of course the present invention is not limited to the described embodiments limited.

So can glass composite of several different Starting mixtures (raw material mixtures) are generated, of which not all old glass powder containing ceramic short fibers included. Also can the pressed blank is heat treated outside the mold become.

Generally, the following production sequence is particularly preferred: a dry powder mixture of glass powder and ceramic short fibers is placed in a mold and pressed at a moderate pressure <1 MPa. Subsequently, the compressed powder mixture in the mold at 800-900 ° C, preferably 800-850 ° C, heat treated. The heat treatment time depends on the size of the component and is approximately 30 to 60 minutes (preferably 40 to 60 minutes) for a plate of size about 300 × 120 × 10 mm ³ , by way of example. The subsequent cooling should be done slowly. In this manufacturing process, the surface structures of the non-heat-treated powder mixture remain largely intact.

Depending on the powder composition and the manufacturing parameters, general ceramic-like materials can be produced, in particular with the following properties: Bending strength: 30-75 N / mm2 Modulus of elasticity: 20-45 kN / mm2 Impact resistance: 15-120 kJ / m2 Hardness / abrasion resistance: 150-1000 mg downforce / Taber Abraser test Porosity: 5-30% shrink: 0-25% Thermal conductivity: 0.8-2.0 W / mK

Abrasion resistance was measured by a Taber Abraser method, e.g. B. after ISO 9352 , ASTM D 1044 or DIN EN standard 438-2.6 , determined. In this process, wheels provided with abrasive paper are pressed against the rotating surface of the specimens at a defined pressure. The measured variable is usually the mass loss of the specimen after a certain number of revolutions. In this case, grinding wheels of the type H-18 were used. There were 500 revolutions driven. The two grinding wheels were each weighted with 500 g.

One Test of thermal resistance by multi-day Storage of flat moldings at 600 ° C under mechanical stress has no significant deformation led the sample.

Possible Applications of the glass composite include u. a. Burner caps, Surface grill radiator, soleplate, Top panel, gas well.

Dependent from the respective requirement profile, this material can material technology and / or economically an alternative to the manufacture of components be hitherto made of ceramic and / or metallic materials were made.

in the The following are by way of example and not limiting as the invention to understand four more manufacturing processes.

example 1

When Starting materials are 61.6 g of waste glass powder and 8.4 g of calcium silicate fibers according to a mass ratio of 88%: 12% used. The two components are homogeneously mixed together and then poured into a pan. A first consolidation takes place by shaking and knocking, so without conventional Pressing, d. h., That the pressing pressure is 0 Pa. The Sample is heated for 30 minutes at 800 ° C, z. In one Standing oven or a continuous furnace. The result is a mechanical one more stable, so one-piece, shaped body.

Example 2

950 g of waste glass powder and 190 g of calcium silicate fibers are used as starting materials (mass ratio 83.3%: 16.7%). The used glass powder is treated with silicone oil during its production in order to increase the fluidity of the powder. The two components earth homogeneously mixed together. This mixture is in a boron nitride coated mold (cordierite, base 294 × 134 mm ² ) filled. By gentle shaking, a first smoothing of the sample takes place. Subsequently, the sample is pressed at low pressure. The sample is heated for 60 minutes at 800 ° C. The result is a mechanically stable, one-piece plate with a thickness of about 13 mm.

Example 3

Production of a sandwich molding, z. B. after 3 consisting of two denser outer layers A and C and a porous inner layer B. The outer layers A and C consist of an old glass powder / calcium silicate fiber mixture, the middle layer B of an old glass powder / calcium silicate / calcium carbonate powder mixture. The used glass powder was treated with silicone oil during its production in order to increase the fluidity of the powder. The material composition of the individual layers is as follows: Layer A: 320 g waste glass powder, 64 g calcium silicate fibers; Layer B: 320 g waste glass powder, 64 g calcium silicate fibers, 16 g calcium carbonate powder; Layer C: 320 g glass powder, 64 g calcium silicate fibers. The components of the individual layers are each mixed homogeneously. The powder mixture for layer A is filled into a boron nitride-coated molding tool (cordierite, ground area 294 × 134 mm). Slight shaking smoothes the sample. To ensure a better adhesion of the individual layers with each other, the sample surface is roughened. The powder mixture for layer B is filled onto the roughened surface of layer A. Slight shaking smoothes the sample. To ensure a better adhesion of the individual layers with each other, the sample surface is roughened. The powder mixture for layer C is filled on the roughened surface of layer B. Slight shaking smoothes the sample. Subsequently, the sample is pressed with a low pressure. Then vent holes (diameter about 1 to 2 mm) are introduced through layer C in layer B (hole density about 6000 holes / m ² ). The sample is heated for 60 minutes at 800 ° C. The result is a mechanically stable, one-piece three-layer sandwich panel with a total thickness of about 19 mm, z. B. analogous to 3 ,

Example 4

manufacturing a shaped body, in particular as a burner cap of a Gas well can be used. Material composition: 22.5 g glass powder, 4.5 g calcium silicate fibers, 1.0 g stainless steel wire pieces, 4.5 g of iron powder, 5.0 g of copper powder. The old glass powder is added its preparation is treated with silicone oil to increase fluidity of the powder increase. The stainless steel wire pieces have lengths of about 8-20 mm (mostly 10-15 mm). The particle sizes of the iron and copper powders are in the range of waste glass powder particle sizes. The components are mixed homogeneously with each other. This mixture is in a boron nitride coated mold (consisting made of a metallic material). By gentle shaking a first smoothing of the sample takes place. Subsequently becomes a stamp with the negative shape of the burner cover bottom placed on the filled mold and the mixture pressed with a light pressure. Thereafter, the burner cover blank in the mold with attached punch for 16 minutes heated at 800 ° C. The result is a mechanical stable, one-piece burner cap with a diameter of 75 mm.

The Calcium silicate fibers are generally used to reduce, among other things of shrinking. The stainless steel wire pieces serve among other things for increasing the mechanical stability, in particular Breaking strength. The metal powder serves among other things to increase the thermal conductivity, magnetic properties, coloration of the molding, increasing the mass. The silicone oil (eg AK1000 from Wacker, preferably about 0.2 to 0.8 g of silicone oil to 1 kg glass, especially 0.3 g to 0.7 g, particularly preferred approx. 0.5 g) serves, among other things, to increase the fluidity.

Of course the invention is not limited to the embodiments. So can also a fine-grained starting waste glass powder (eg with D50 = 5 μm) or a coarse-grained one Powder (eg with D50 = 22 microns or more) can be used. Also, the skilled person will be aware of this description in the Be able to decide if or when to add silicone oil becomes. Also, on a (organic or inorganic) propellant be waived; if no propellant is used, can yet sporadically pores remain in the matrix. Also Of course, the invention is not on the above listed powder composition and / or manufacturing parameters limited. In addition, instead of ceramic short fibers additionally or alternatively mineral short fiber, or generally longer fibers. Instead of vent holes are also other forms of venting channels possible, for. B. cracks. Generally, a heat treatment be carried out by any suitable method, z. B. by standing or continuous furnaces. The heat treatment can under normal atmosphere, under special atmosphere (eg nitrogen, noble gas, etc.) or take place in vacuo. Further, the raw material mixture may also be heat treated for more than 75 minutes become. Also, it should be the expert after reading this description be clear that it is due to a parameter variation of the manufacturing process (eg with respect to a temperature, duration of the heat treatment, change the material composition [fiber content, proportion of metal powder, proportion stainless steel wire pieces, etc.]) is possible, the Material properties of the finished body in a wide Range to vary.

1

Glass composites

2

Glass- or glass-ceramic matrix

3

ceramic short fiber

4

pore

5

Glass composites

6

starting mixture

7

starting mixture

8th

Glass composites

9

Material layer

10

Material layer

11

vent hole

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 1925009 B2 [0003]
• - DE 4416489 C1 [0004]
• - EP 0718249 A1 [0005]
• - DE 3318813 C2 [0006]
• - DE 3731649 [0007]

Cited non-patent literature

• - ISO 9352 [0045]
• - DIN EN standard 438-2.6 [0045]

Claims (21)

Method for producing a glass composite body ( 1 ; 5 ; 8th ), characterized in that it comprises the following steps: - preparation of at least one raw material mixture ( 6 . 7 ), which are filled with fibers ( 3 ) comprises offset glass powder, wherein the glass powder at least partially comprises an old glass powder; - forming the at least one raw material mixture in a mold; Heat treating the shaped at least one raw material mixture to be joined to a one-piece body ( 1 ; 5 ; 8th ). Process according to claim 1, characterized in that the glass powder of the raw material mixture ( 6 . 7 ) consists entirely of waste glass powder. Method according to claim 1 or 2, characterized in that the fibers ( 4 ) comprise ceramic and / or mineral fibers. Method according to one of the preceding claims, characterized in that the fibers ( 4 ) Calcium silicate fibers, in particular with a mass fraction of the calcium silicate fibers in a glass powder-calcium silicate fiber mixture in the range of 0 to 50%, especially between 5 and 35%, more particularly between 12 and 17%. Method according to one of the preceding claims, characterized in that the fibers short fibers ( 4 ). Method according to one of the preceding claims, characterized in that the step of molding is compression molding includes. Method according to Claim 6, characterized that the compression is carried out at a pressure of not more than 1 MPa becomes. Method according to one of the preceding claims, characterized in that the step of forming is shaking or knocking the mold. Method according to one of the preceding claims, characterized in that the step of heat treating comprises bonding by means of sintering and / or melting. Method according to one of the preceding claims, characterized in that the raw material mixture ( 6 . 7 ) between 650 and 1000 ° C, in particular between 750 and 900 ° C, especially between 800 and 850 ° C, is heat treated. Method according to one of the preceding claims, characterized in that the raw material mixture ( 6 . 7 ) is not heat treated for more than 75 minutes, in particular not more than 60 minutes. Method according to one of the preceding claims, characterized in that the raw material mixture ( 6 . 7 ) is heat treated in the mold. Method according to one of the preceding claims, characterized in that the raw material mixture at least a metallic constituent is added, in particular metal powder, Metal granules, metal flakes, metal wire pieces and / or Metal fibers. Method according to one of the preceding claims, characterized in that the raw material mixture at least a further ceramic ingredient is incorporated, in particular other ceramic fibers, ceramic powder and / or ceramic granules. Method according to one of the preceding claims, characterized in that the raw material mixture is incorporated with pigments become. Method according to one of the preceding claims, characterized in that the raw material mixture at least another inorganic material, in particular powder, granules and / or fibers. Method according to one of the preceding claims, characterized in that at least two raw material mixtures ( 6 . 7 ), of which at least one fiber powder mixed with fibers. Method according to one of the preceding claims, characterized in that the glass powder of the raw material mixture by means of a fluidizing agent, in particular by means of silicone oil, is fluidized. Method according to claim 18, characterized that the silicone oil in a mass of 0.2 to 0.8 g, especially from 0.3 g to 0.7 g, especially from about 0.5 g, per 1 kg of waste glass is added. Household appliance component ( 1 ; 5 ; 8th ), characterized in that it has been produced by means of a method according to one of the preceding claims and is provided in normal operation with the domestic appliance for use under a temperature load. Domestic appliance component according to claim 20, characterized characterized in that it is used as a burner cap, surface grill radiator, Iron sole, top panel or gas well is designed.