DE202007004774U1 - A ceramic metal matrix composite wear resistant part, a ceramic metal matrix composite ceramic part, abrasive roll and table top ceramic part comprising a ceramic metal matrix composite part - Google Patents

Abstract

Wear part off ceramic metal matrix composite (MMCC), wherein the wearing part has a wear section comprises, which is formed by a ceramic cake (1), the impregnated with metal (4) wherein the ceramic cake comprises ceramic grains (2), the alumina wherein the ceramic cake (1) further comprises grains (5) comprising a material selected from the group consisting made of boron carbide, silicon carbide or tungsten carbide.

Description

AREA OF INVENTION

The The invention relates to a wear part of ceramic metal matrix composite and a ceramic cake for use in a ceramic Metal wear part. The invention also relates to a process for the preparation of a ceramic cake for use in a wearing part ceramic metal matrix composite. The invention further relates an abrasive roll that is a wear part of ceramic metal matrix composite includes, and a table cover for a vertical lathe, the a wearing part of ceramic metal matrix composite.

Lots Commercial applications concern components that will over the course of Operating life of the component wear out. The applications of parts, the wear-resistant have to be are in the cement, mining and thermal power generation industries quite commonplace. Historically, during the first half of the twentieth century 12% Mn steel and NiHard materials for wear-resistant applications used. For the past 50 years, heavy chromium-containing iron has been used for wear-resistant applications successfully used and have NiHard and 12% Mn steel materials Mostly replaced.

The Finding a further improved wear resistance was continued and in the last 15 years, ceramic metal matrix composites have become with varying degrees of success for wear-resistant applications used. The present invention is in the same Range and improves the economy and wear characteristics essential compared to currently used composites. ceramic Metal matrix composites include ceramic parts that are in a Embedded metal matrix.

BACKGROUND AND REFERENCES TO THE PRIOR ART

in the With regard to ceramic metal matrix composites, the first is Decision of course the choice of the ceramic material, which is usually in the form of granules. Aluminum oxide is known as a good abrasive material. In this Context is U.S. Patent No. 3,181,939 issued May 4, 1965 to Douglas W. Marshal (represented by: Norton Company Mass, USA). The patent describes the production of abrasives from molten alumina-zirconia, which the good wear resistance properties of alumina with the hardness of zirconium oxide combine. Consequently, alumina / zirconia grains appear to be the most suitable candidates for ceramic metal matrix composites to be. Ullmann's Encyclopedia of Industrial Chemistry, fifth full revision, part A1, volume A1, section 2.2, describes useful Alumina / zirconia grains.

One Casting with embedded hard material has been described in German Patent (by Dr. Wahl) No. 7326661 of 20.07.73.

The Japanese Patent by Hr. Tamura of KHI (Patent No. 62286661 of 12.12.87) describes a process for impregnating ceramic particles with molten metal, around a composite casting with good wear resistance manufacture.

A European patent (No. EP 0 575 858 B1 dated Jun. 23, 1992), filed by Staub Fritz (assignee: Zuzel Inotech AG), describes the production of a ceramic metal matrix composite casting having porous ceramic elements on the wear surface. The ceramic particles used are described as corundum, zirconium oxide or magnesium oxide.

In US Pat. No. 6,399,176 B1 of 04.06.2002 is the production a composite wear component described by casting process. Ceramic cakes were introduced on the wear surface, the from a homogeneous solid solution from 20 to 80% alumina and 80 to 20% zirconia.

Even though Thus, there are many examples of composite wear components There is still a need for further improvement the wear resistance. Such further improvement increases the effectiveness of the wear component.

TASK OF THE INVENTION

It is an object of the invention to provide a ceramic metal matrix composite consumable and a ceramic cake for use in a ceramic metal wear member having improved wear resistance. The known devices require improvement. If a composite consumable is worn, the part must be replaced. Consequently, during the replacement of the worn part, no device using the wearing part can be used. The replacement of the worn part results in a loss of the operating time of the device. An improvement in the wear resistance leads to a reduction in the percentage of time lost in replacing worn parts of such devices as grinding rollers and table liners, the wear parts of ceramic Metallma Use trix composite.

SUMMARY THE INVENTION

The Invention provides a consumable part made of ceramic metal matrix composite, wherein the wearing part a wear section comprises, which is formed of a ceramic cake with Metal impregnated wherein the ceramic cake comprises ceramic grains containing alumina wherein the ceramic cake further comprises grains which are a material include that selected is from the group consisting of boron carbide, silicon carbide or Tungsten carbide.

The The present invention provides ceramic cakes containing a improved wear resistance exhibit.

Preferably is the amount of carbide grains between 1 and 25% by weight of the ceramic cake for boron carbide, preferably 2 and 10 wt .-%. Has a very small amount of carbide grains only a moderate effect, whereas a big one Addition of carbide grains no additional Advantage provided.

In a preferred embodiment consist of the carbide grains mainly from Borkarbid. Boron carbide is the hardest and lightest of the carbide materials mentioned.

consequently the present invention achieves an improvement of the wear properties of ceramic metal matrix composite parts produced by an addition of carbide grains to the grains, comprising alumina.

In a preferred embodiment include the ceramic grains Alumina, zirconia and titania, the alumina average in an amount of from 30 to 65% by weight, the zirconia in one Amount of 30 to 65 wt .-% and the titanium oxide in an amount of 1 to 7 wt .-%, all percentages in terms of Weight of the grains are indicated.

The Inclusion of zirconium oxide in the grains comprising alumina a positive effect on the wear resistance of the grains. The Absorption of titanium oxide in the grains has another positive impact on wear resistance. Titanium oxide itself is significantly softer than aluminum oxide and zirconium oxide, which makes the positive impact all the more significant. Preferably lies the amount of titanium oxide is between 2 and 6 weight percent, most preferably between 3 and 5.5% by weight. The positive impact on the wear resistance is most evident within these weight percentages.

The Percentages of alumina and zirconia are preferably between 40 and 55% alumina and 40 to 50% zirconia.

It It should be noted that the alumina / zirconia / titania composition from grain to grain within the wear part of ceramic metal matrix composite change can. All mentioned above Percentages refer to average percentages the grains.

Furthermore the inventors are in view of even more preferred embodiments thereof become aware that in the production of a ceramic cake from grains the binding properties of the grains important because the grains are relative are crude. Consequently, there is a need for the addition of other ingredients to the ceramic grains, around the bond between the grains and to improve the formability of the material from which the ceramic Cake is made. One such ingredient is sodium silicate, the binding of the grains supports and improves moldability.

The Inventors have recognized that the addition of a very fine ceramic Powder, which preferably consists of alumina powder, not only improves the formability, but also the hardness of the cake, so that the wear resistance of the final product increased becomes. "Very fine powder "refers on a powder of a size that Significantly smaller (at least one, preferably two orders of magnitude) as the size of the ceramic Alumina / zirconia / titania grains. Such a fine ceramic powder is preferably used in terms of Weight of the ceramic grains (Alumina / zirconia and carbide) in a weight percentage of between 1 and 4 wt .-% mixed. Preferably, the grain size of the fine ceramic powder in a FEPA range of 1000 to 1400 mesh sizes. Preferably lies the grain size of the alumina comprehensive grains and the carbide grains in a FEPA range of 6 to 12 grid sizes.

The Mixture of the above-described ceramic grains, a fine ceramic (alumina) powder and sodium silicate is preferably in flexible containers of suitable forms, the preferably having a rubber core filled. The cakes are still located in core containers, are fumigated and baked to develop good firmness.

The produced ceramic cakes are attached to desired surfaces of molds and liquid metal is poured into the cavity to produce ceramic metal matrix composite castings.

SUMMARY THE FIGURES

These and further aspects of the invention will be more detailed and exemplified with With reference to the accompanying drawings. Show it:

1 : a ceramic cake of the prior art,

2 : a ceramic cake of the prior art with infiltrated metal,

3 a ceramic cake for a wear part of ceramic metal matrix composite according to the invention,

4 a rubber core container

5 an abrasive roll comprising a ceramic metal matrix composite consumable;

6 a table covering comprising a ceramic metal matrix composite consumable;

7 and 8th : show ceramic cake arrangements.

The Figures are not to scale shown. In general, the same components are in the figures marked with the same reference numerals.

DETAILED DESCRIPTION AND EMBODIMENTS THE PRESENT INVENTION

1 represents a ceramic cake of the prior art. The ceramic cake 1 includes ceramic grains 2 and often a binder 3 , The binder is in 1 shown schematically as a thin layer around some of the grains.

2 shows a ceramic cake 1 out 1 that with metal 4 impregnated to form a wear part of ceramic metal matrix composite (MMCC). To impregnate the ceramic cake, molten metal is introduced. The molten metal fills the spaces between the grains 2 to produce a part of ceramic metal matrix composite. The metal forms the matrix for the ceramic grains. For this reason, such parts are called "parts of ceramic metal matrix composite".

The Applications of parts that need to be wear-resistant are in the cement, mining and thermal power generation industries quite commonplace.

It For example, the present invention has succeeded in reducing wear characteristics of ceramic metal matrix composite parts, which by introducing of ceramic grains reached at the wear surface becomes. The invention combines the use of in the ceramic cake Alumina / zirconia grains and grains made of boron, silicon or tungsten carbide.

3 schematically shows a ceramic cake for a wear part of ceramic metal matrix composite according to the invention. The difference between 1 according to the prior art and 3 is the addition of boron, silicon or tungsten carbide grains 5 and a fine alumina powder 6 ,

In two trial runs were 5 to 20% by weight of boron carbide grains contained in the ceramic cake.

In The two cakes each consisted of 87% and 72% of the ceramic Alumina / zirconia / titania grains cake Alumina in the range of 30 to 65%, zirconia in the range from 65 to 30% and titanium oxide in the range of 1 to 7%, the alumina and zirconia contents in the alumina / zirconia / titania grains average about 50%, and the titanium oxide content was about 5%, 3% by weight. of the ceramic cake were fine alumina powder and about 5% by weight of the ceramic cake was an inorganic binder. In In the examples, each grain was the alumina and zirconia contained, at a microscopic level, a phase mixture formed of different solid phases. The grains were not considered one homogeneous solid solution educated. Alumina / zirconia grains which used in the preferred examples have as ingredients Alumina and zirconia on. Inside is such grains the composition is not homogeneous, but a phase mixture is present this means, different parts of the grain have a different composition on, with some parts forming a solid phase, the first Percent alumina and a second percent zirconia includes, and other parts a different solid phase or solid phases form different percentages of alumina and zirconia or mainly are formed of alumina or zirconia. The solid phases can Include titanium oxide. The grain as a whole is in the form of a Phase mixture before.

5% by weight of boron carbide corresponds to about 7.5% by volume due to the difference in the specific gravitational force of the carbide grains to the specific gravity of grains comprising alumina / zirconia. 20% by weight corresponds to about 27.5% by volume. The difference in the specific attraction force between boron carbide (about 2.5 g / cm ³⁾ and alumina / zirconia (about 3.8 g / cm ³⁾ means that a percentage by weight between 1 wt .-% and 25 wt .-% a Percent by volume of the carbide grains in the ceramic material is between 1.5 vol.% And 34 vol.%. If particles of equal size were used, that is, the volume of each alumina / zirconia and boron carbide grain were the same, this would mean that one out of every 60 to 1 in 3 grains and carbide grains comprising all alumina / zirconia would be a carbide grain is.

The same volume percent range results for silicon carbide grains with a higher specific attraction force of 3.2 g / cm ³ in a weight range between 1.2 wt .-% and 30 wt .-% and for tungsten carbide grains with an even higher specific attraction force of 15 g / cm ³ to a weight range between 5.6 wt .-% and 66 wt .-%.

The boron carbide grains and the alumina / zirconia / titania grains in the examples had the same lattice size, with the lattice size in Examples FEPA 10 was.

Of the Wear of ceramic metal composites with such ceramic cakes, the boron carbide grains have been associated with the wear of ceramic metal composites compared with the same texture but without boron carbide grains.

It It has been found that an addition of 5 wt .-% boron carbide grains to a reduction of the wear rate by about 15 % led; With the addition of 20% by weight of boron carbide grains did not cause further reduction the wear rate noticed.

As explained above these results contradict the state of the art. Surprised For example, adding even a relatively small amount of carbide grains has one positive impact. The increase the wear resistance is not proportional to the amount of added boron carbide grains, which indicates the presence of a cooperative effect, the Recording even a relatively small amount of carbide (between 2 and 10%) a protective effect has, reducing the wear resistance is increased.

The beneficial effect has been found to be significant in a range of 5% proved higher than in a range of 20%. A preferred weight range for boron carbide is between 2 and 10 wt .-%.

One preferred weight range for Borkabridkörner between 2 and 10% by weight corresponds to a weight range for silicon carbide between 2.5 wt% and 12.5 wt% and for tungsten carbide one weight range between 3.6% by weight and 40% by weight.

The Grain sizes of ceramic grains are usually expressed in grid sizes. The recommended Grid sizes for Use in the manufacture of a ceramic metal matrix composite are in the range of 6 to 12 grid sizes according to the FEPA standard. Preferably have the alumina / zirconia and carbide grains one comparable grid size, this means, they differ by no more than 4 grid sizes, preferably by no more than two grid sizes.

In order to be able to arrange such grains at desired locations, the formation of cakes of a required shape is necessary. In addition, such cakes must have adequate strength to withstand any sinking by liquid metal. It has been found that the addition of a very fine ceramic powder, preferably comprising alumina powder, together with sodium silicate, provides improved moldability and achieves an increase in strength. The addition of fine alumina powder with a mesh size of 1000 to 1400, preferably 1200, imparts thixotropic properties. Preferably, fine alumina powder is used, however, within the scope of this preferred embodiment of the invention, other fine ceramic powders, for example zirconia or alumina / zirconia powders, could be used. 4 shows schematically the inclusion of a fine alumina powder 6 ,

The Mixture of the mineral particles described above and of the ceramic, preferably alumina powder is preferably with a suitable Binder such as sodium silicate mixed. However, the inventor has recognized that such a mixture sometimes does not provide adequate raw strength (the is called, Strength in the raw, not yet baked state) and has the forms of ceramic cakes, as the inventor has realized preferably in flexible, preferably rubber, for example Silicone rubber core containers be recorded. The use of rubber core containers for Production of ceramic cake is a feature of a preferred one Embodiment of the Process of the invention.

4 shows schematically the use of a rubber core container 7 around the ceramic cake 1 ,

The The mixture described above is incorporated in the rubber core containers a desired one Have shape, filled and treated with carbon dioxide to provide adequate strength to develop for editing. Other ceramic forms in the Rubber core containers are heated to between 80 and 80 for one to four hours up to 220 ° C heated so that the appropriate strength is generated.

The Cakes are desired surfaces arranged the refractory molds. After closing the Mold arrangements become fluid Metal poured into the cavity. The liquid metal composition will depend on the application selected. impact-resistant Applications can Steel require and shock prone Applications can Tolerate iron. The chrome steels can with the addition of other alloying elements such as Mn, Mo, Ni and Cu between 0.2 to 1.2% C and 2 to 8% Cr. The Mn steel can between 0.8 to 1.2% C and 8 to 14% Mn with other elements as present SI, Cr, S and P additions and impurities. The iron can between 1 to 3.5% C, 11 to 28% Cr with the addition of other alloying agents Contain elements such as Mo, Ni and Cu.

in the Generally be for Wear resistance applications usually the above-mentioned steel and iron types used. However, the procedure is alike for all non-ferrous alloys applicable.

The Molds are opened after a reasonable cooling time and the thus prepared wear parts become a special heat treatment puts out so that the metallic section has better wear resistance developed.

EXAMPLES

A wearing part, which is described as an abrasive roller used by thermal energy stations, was manufactured by the above method. This part was made by centrifugal casting. The manufacturing sequence involved making cake from mineral granules, introducing the cakes and making composite castings called inserts, placing the inserts in the spinneret, and pouring SG iron into the turret around the composite casting to create. The casting produced in this way was heat treated and tried in the wear application. It demonstrably and significantly improved the lifetime of the wear components. 5 introduces a vertical spindle lathe with castings of ceramic metal matrix composite MMCC on the grinding table 8th and grinding rollers 9 represents.

Another wearing part, which is described as a table top for a vertical lathe, was made. Mineral grain cake was introduced at the wearing surface of the casting. The casting was made by a conventional casting process. 6 shows very schematically a table cover 10 with parts of MMCC ceramic metal matrix composite as inserts. The casting was heat treated and machined and tested for wear properties. A significant improvement of up to 15% in wear resistance, see the examples above, was observed by the addition of carbide grains for vertical lathe table liners.

3 represents a simple design for the ceramic cake. Within the scope of the invention, the ceramic cake can be formed into various shapes and shapes and the ceramic cake can be arranged in various patterns. 7 and 8th represent such forms and shapes and patterns. 7 represents an arrangement of strip-like ceramic cake. 8th shows a ceramic cake, with large openings 11 and small openings 12 is provided. These openings are provided on a rectangular grid. 7 and 8th are given as examples.

It It is noted that the use of a mixture of mentioned carbide grains included in the concept of the invention.

ADVANTAGES OF PRESENT INVENTION

The present invention enables the use of ceramic metal wear parts with better wear resistance properties than that of the ceramic metal wear parts resulting from the prior art Technics are known.

In a preferred embodiment The present invention improves wear resistance even further and improves the moldability of the mixtures by adding a fine ceramic powder, preferably from Alumina.

The Use of flexible, preferably silicone rubber core containers, the Part of an embodiment of the present invention also enables the production of cakes of complex shape.

Claims (28)

A wear part of ceramic metal matrix composite (MMCC), the wear part comprising a wear portion passing through a ceramic cake ( 1 ) formed with metal ( 4 ), wherein the ceramic cake comprises ceramic grains ( 2 comprising alumina, wherein the ceramic cake ( 1 ) further grains ( 5 ) comprising a material selected from the group consisting of boron carbide, silicon carbide or tungsten carbide. consumable ceramic metal matrix composite according to claim 1, wherein the carbide is boron carbide. consumable ceramic metal matrix composite according to claim 2, wherein the boron carbide content in the ceramic cake is between 1% by weight and 25% by weight. consumable ceramic metal matrix composite according to claim 3, wherein the boron carbide content in the ceramic cake is between 2% by weight and 10% by weight. consumable ceramic metal matrix composite according to claim 1, wherein the carbide is silicon carbide. consumable ceramic metal matrix composite according to claim 5, wherein the silicon carbide content in the ceramic cake is between 1.2 Wt .-% and 30 wt .-% is. consumable ceramic metal matrix composite according to claim 5, wherein the silicon carbide content in the ceramic cake is between 2.5 Wt .-% and 12.5 wt .-% is. consumable ceramic metal matrix composite according to claim 1, wherein the carbide is tungsten carbide. consumable ceramic metal matrix composite according to claim 8, wherein the tungsten carbide content in the ceramic cake is between 5.6% by weight and 66% by weight. consumable ceramic metal matrix composite according to claim 8, wherein the tungsten carbide content in the ceramic cake is between 3.6% by weight and 40% by weight. consumable ceramic metal matrix composite according to any one of the preceding claims, wherein the grains comprising alumina Alumina, zirconia and a quantity of titania. consumable ceramic metal matrix composite according to claim, wherein said Titanium oxide content in the grains comprising alumina between 2 and 6 wt .-% is. consumable ceramic metal matrix composite according to claim 12, wherein the amount of titanium oxide in the alumina / zirconia grains between 3 and 5.5 wt .-% is. consumable ceramic metal matrix composite according to any one of the preceding claims, wherein the amount of alumina is between 40 and 55% by weight. consumable ceramic metal matrix composite according to any one of the preceding claims, wherein the amount of zirconium oxide is between 40 and 50% by weight. consumable ceramic metal matrix composite according to any one of the preceding claims, wherein the grid size of the ceramic grains in a FEPA range of 6 to 12. A ceramic metal matrix composite consumable according to any one of the preceding claims, wherein the ceramic cake further comprises a fine ceramic powder ( 6 ). consumable ceramic metal matrix composite according to claim 17, wherein the ceramic cake in terms of the weight of the ceramic grains from 1 to 4% by weight of fine ceramic powder. A ceramic metal matrix composite wearing part according to claim 17 or 18, wherein said fine ceramic powder ( 6 ) has a grid size that is at least two orders of magnitude smaller than the grid size of the ceramic grains ( 2 . 5 ). consumable ceramic metal matrix composite according to any one of claims 17 to 19, wherein the fine ceramic powder comprises alumina powder. consumable ceramic metal matrix composite according to any one of claims 17 to 20, where the grid size of the fine ceramic powder in a FEPA range of 1000 to 1400. A ceramic metal matrix composite wearing part according to any one of the preceding claims, wherein the ceramic cake comprises sodium silicate as a binder ( 3 ). A ceramic metal matrix composite wearing part according to claim 12, comprising Sodium silicate binder in the range of 4 to 6%. consumable ceramic metal matrix composite according to any one of the preceding claims, wherein the wearing part made of ceramic metal matrix composite either chrome steel, the between 0.2 to 1.2% C and 2 to 8% Cr, with the addition of other alloying Elements such as Mn, Mo, Ni and Cu include or Mn steel, which is between 0.8 to 1.2% C and 8 to 14% Mn, with addition and impurities includes other elements such as Si, Cr, S and P, or the iron that between 1 to 3.5% C, 11 to 28% Cr, with the addition of other alloying elements such as Mo, Ni and Cu. Ceramic cake ( 1 ) for a ceramic metal matrix composite (MMCC) wear part according to any one of the preceding claims. Sanding roller ( 9 ) comprising a ceramic metal matrix composite (MMCC) consumable part according to any one of claims 1 to 24. Grinding roller lathe comprising an abrasive roller according to claim 26. Table covering ( 10 ) for a vertical lathe comprising a ceramic metal matrix composite (MMCC) wear part according to any one of claims 1 to 24.