GB2331517A

GB2331517A - Binding ceramic materials

Info

Publication number: GB2331517A
Application number: GB9825279A
Authority: GB
Inventors: Christopher Patrick Howland; Kevin James Moeggenborg
Original assignee: Nalco Chemical Co
Current assignee: ChampionX LLC
Priority date: 1997-11-25
Filing date: 1998-11-18
Publication date: 1999-05-26
Anticipated expiration: 2018-11-18
Also published as: FR2771407A1; ATA191998A; CZ375298A3; BE1012447A5; PL329755A1; AT407155B; DE19853217A1; TW400312B; GB9825279D0; GB2331517B; AT407155B8; FR2771407B1; JPH11255564A

Abstract

A method for binding ceramic materials in aqueous media utilizes water soluble hydrophobic/ hydrophilic block copolymers for binding various classes of ceramic materials. The hydrophilic mer units of the block copolymer are selected from oxyalkylene units, acrylic acid and methacrylic acid and the hydrophobic mer units are selected from styrene, methyl methacrylate and butyl methacrylate.

Description

1 2331517

Field of the Inygntion

A method for binding ceramic materials in aqueous media is disclosed.' The method utilizes hydrophobic/hydrophilic block copolymers for binding various classes of ceramic materials.

Backgrgund of the Invention Ceramic materials are commonly prepared by mixing powdered ceramic oxides such as magnesia, alumina, titania and zirconia, in a slurry along with additives, such as dispersants and binders. The slurry may be spray dried to produce ceramic particles. The particles are formed into an aggregate structure, called a "green ceramic", having a desired shape and subsequently subjected to a severe heat treatment known as sintering. The si-ntering process converts the green ceramic into a cohesive "fired ceramic", having a nearly monolithic polycrystalline ceramic phase.

The binder serves to hold the ceramic particles of the green ceramic in the desired shape after forming. The binder can also provide lubrication while the particles are pressed. Preferably, the binder combusts or vaporizes completely during the sintering process leaving no trace of the binder in the fired ceramic. In performing these functions, binders significantly affect the properties of the fired ceramics which are ultimately produced.

In commercial practice, poly(vinyl alcohols) are widely used as ceramic binders. Additionally, poly(ethylene oxide) and ethylene-vinyl acetate copolymers reportedly have been used as binders for particulate material, such as granular silica gel.

-7 2 For example, polymeric binders containing substantially hydrolyzed copolymers made from monomers having ester or amide functional groups, poly(vinylformamide) or a copolymer of vinyl alcohol and vinyl amine are disclosed in U.S. Patent Nos. 5,358,911; 5,487,855 and 5,525,665.

Spray drying is an evaporative process in which liquid is removed from a slurry containing a liquid and a substantially non-volatile solid. The liquid is vaporized by direct contact with a drying medium, usually air, in an extremely short retention time, on the order of about 3 to about 30 seconds. The primary controlling factors in a spray drying process are particle size, particle size distribution, particle shape, slurry density, slurry viscosity, temperature, residence time, and product moisture.

The viscosity of the slurry must be suitable for handling and spraydrying. Al_Ii6ugh spray-drying equipment conditions may be adjusted to handle a variety of viscosities, larger particles will usually result from higher viscosity slurries.

Those of ordinary skill in the art are familiar with the spray-drying process used in the production of ceramic materials, and will be able to optimize the control factors of spray-drying to best advantage. Alternatively, the spray drying or dry pressing processes may be replaced by other well known fdrming methods, such as granulation, tape casting and slip casting.

Spray drying of the slurry produces substantially dry, free-flowing powder particles which contain the ceramic, the binder and the optional materials described 3 above. The dry particles are granules which are generally spheroidal in shape and have an effective diameter of about 50 to about 300 micrometers. Typically, about 0.5 percent to about 8 percent of the binder, based on the dry weight of the ceramic powder, is present in the dry particles.

In granulation, a mixture of dry powder or powders is mixed or rolled, commonly in a barrel shaped apparatus. Water and/or a binder solution is sprayed into the mixing powder causing aggregation of the small particles into larger granules. The size of the granules is controlled by the amount of material sprayed into the powders and the speed with which it is sprayed. Granulated powders may be screened to a desired size and pressed to shape in a pressing operation prior to sintering. Alternatively, the granules themselves may be the desired product and may be sintered directly.

Tape casting is commonly 'Used to produce thin substrates for the electronics industry. In the process, a thick ceramic slurry containing ceramic powder, dispersant and binders is prepared. This slurry is cast onto a smooth surface such as a Mylar or plastic sheet and the thickness is controlled by passing the sheet under a blade which smoothes the slurry surface and scrapes off excess material. The slurry tape is dried to a plastic state and cut and shaped to specification. The amount of binders present in tape casEing is very high, typically on the order of 15 to 20 wt. of the ceramic powder mass.

In fluidized,bed spray drying, small "seed" particles are placed in a column and hot air is blown 1 4 into the seed powder from below suspending the particles in the column. A ceramic slurry is sprayed onto'the seed particles from above, causing them to grow. When the particles reach a large enough size, they are siphoned out of the dryer while more seed particles are introduced. This process can produce powder for further forming processes, or the powder itself may represent the desired product, in which case it would be sintered to produce the final ceramic., The dry particles are comp acted to produce an aggregate, green ceramic structure. Preferably, the particles are compacted by pressing in dies having an internal volume which approximates the shape desired for the final fired ceramic product. Alternatively, the particles are compacted by roll compacting or other wellknown compacting methods. The spray dried blend of powder, binder, and optional surfactants and lubricants is relatively free flowing so tlt it can enter and closely conform to the shape of the pressing dies.

Inside the dies, the dry particles are subjected to a pressure which is typically in the range of about 2000 to about 50,000 psi. Pressing the particles produces an aggregate structure, called a green ceramic, which retains its shape after removal from the die.

One forming technique used for spray dried or granulated material is roll compaction, also referred to as roll pressing. This technique tak(is a dry powder and crushes it between two rollers in a continuous process. This process produces sheets of ceramic of -various widths and thicknesses. 'These sheets can be cut to shape and sintered to produce the final ceramic body. The process is commonly used to produce ceramic substrates for the electronics industry.

Dry pressing involves filling a shaped die with spray dried or granulated powder and pressing it at high pressures. The pressing occurs through movable pistons at the top and/or bottom of the die cavity. The process can be used to produce fairly complex geometries in a single forming step. The ceramic body that results is ejected from the die and sintered to produce a final ceramic product.

Isostatic pressing is similar to dry pressing in that a ceramic powder is pressed in a die cavity. In isostatic pressing, however, all or part of the die wall consists of a flexible material. After filling the die cavity with powder, the die is submerged in a liquid pressure chamber and pressure is applied to squeeze the die and compact the powder. Unlike dry pressing, no movable parts are involved. Isostatic pressing is commonly used on large or very long parts to minimize cracking or lamination of the final ceramic green body.

Extrusion involves the pushing of a concentrated, plastic, slurry through an orifice. The orifice is of the size and shape of the desired ceramic body. This process is commonly used to produce ceramic tubes or similarly shaped pieces. The slurry used is prepared from dry powders which are mixed with water, organic binders and lubricants, and a coagularit. This slurry is usually predried in a filter press or similar apparatus to remove excess water and thicken the slurry to a plastic material.- The material is then extruded through 6 a press which is either piston or screw driven. The extruded material is cut to length, dried, and sintered.

Jiggering is commonly used in the whiteware industry to shape an extruded or filter pressed ceramic slurry. Typically, a portion of the plastic slurry is piaced on a rotating wheel and shaped by rollers and/or knife blades to a desired geometry. This body is then dried and sintered.

Another ceramic forming method, that is used for parts of complex shape, is slip casting. In slip casting, a concentrated ceramic slurry (slip) is poured into a mold with an internal shape of the desired ceramic body. The slurry used must be highly concentrated to prevent settling of particles and/or excessive shrinkage during drying. At the same time, the slip must be fluid enough to completely fill the mold and allow escape of air bubbles. The presence of a polymeric binder adds strength to the cast body preventing breakage during mold removal and handling of the body prior to sintering.

Heating the aggregate structure drives off volatile materials such as water, and burns off organic materials, such as binders or surfactants. When a sufficiently high temperature is reached, the particles of the aggregate structure begin to fuse, but do not fuse completely, and become fastened to one another to reproduce a relatively strong fired ceramic material having essentially the desired shape.

The slurry is, for example, spray d'ried to produce substantially dry particles which include the polymer. The particles are preferably pressed to produce an aggregate, green ceramic structure and heated to produce 7 a fired ceramic material. Alternatively, the particles can be formed into an aggregate, green ceramic structure by roll compaction or other well- known methods.

Thermoplastic block copolymer binders are disclosed in U.S. Patent Nos. 4, 158,688; 4,158,689; 4,568,502 and 4,364,783. However, these elastomers must be heated in order to be mixed with the particulated solids.

A method for stabilizing dispersions of metal oxides and/or carbon black in water in the presence of a dispersant which is a block copolymer comprising at least one block of an ammonium group containing (meth)acrylate is disclosed in U.S. Patent Nos. 5,200,456 and 5,292,591.

other possible uses for the block copolymers described herein include using the polymers as binders in investment casting shells, as waterreducing aids for gypsum wallboard manufacture or as dispersants for metal oxides and/or carbon black.

U.S. Patent No. 5,324,776'discloses polymeric dispersants which are block copolymers of alkylene oxides such as ethylene oxide and propylene oxide. However, only hydrophobic blocks are disclosed in that reference. By contrast, block copolymer ceramic binders are described herein which contain both hydrophobic and hydrophilic block units. U.S. Patent No. 5, 643,996 discloses dispersant/binders which are block copolymers of units of methacrylic acid and alkyl methacrylate in which the alkyl radical can comprise from 1 to 8 carbon atoms. Other ceramic binders were disclosed in JP 60238347A, JP 63159250A and JP 5058711A. However, none of these references disclose the block copolymers described herein.

1 8 Although commercially available binders are_ satisfactory for many applications, a need exists for improved binders which provide still greater strength and/or green density in green ceramic materials. Greater green strength reduces breakage during handling of t green ceramics and, generally, is associated with higher quality fired ceramics. Preferably, the improved binders would be cheaper and more versatile than previously known binders. The value of an increase in density is that it results in decreased shrinkage, dec. reased warpage, and overall improvement of the uniformity of physical properties.

A method for binding ceramic materials in aqueous media is disclosed. The method utilizes hydrophobic/hydrophilic block copolymers for binding various classes of ceramic materials.

The present invention provides an unfired, ceramic precursor material characterized by comprising a mixture of:

a) a ceramic powder selected from the group consisting of aluminum oxide, silicon nitride, itride, silicon carbide, silicon oxide, aluminum n magnesium oxide, lead oxide, zirconium oxide, titanium oxide, steatite, barium titanate, lead zirconate titanate, clays, ferrite, yttrium oxide, zinc oxide, tungsten carbide, sialon, neodymium oxide and combinations thereof aiid having b) a water soluble block copolymer hydrophobic and hydrophilic mer units wherein said selected from the group hydrophilic mer units are of oxyalkylates, acrylic acid and consisting 9 methacrylic acid and said hydrophobic mer units are selected from the group consisting of styrene, methylmethacrylate and butylmethacrylate.

:rhe present invention further provides a method for preparing a ceramic material, characterized by comprising the steps of:

a) mixing a ceramic powder with an aqueous solution containing a water-soluble block copolymer to produce a slurry, said water-soluble block copolymer having hydrophobic and hydrophilic mer units wherein said hydrophilic mer units are selected from the group consisting of oxyalkylates and methacrylic acid and said hydrophobic mer units are selected from the group consisting of styrene, methylmethacrylate and butylmethacrylate.

b) drying the slurry by a process selected from the group consisting of filter pressing, fluidized bed spray drying, spray drying and tape casting to produce particles which include said block copolymer; C) compacting the particles by a process selected from the group consisting of dry pressing, extrusion, isostatic pressing, jiggering and slip casting to produce an aggregate structure; and d) heating the aggregate structure to produce a fired ceramic material.

The information in the following-paragraph pertains to any aspect of this invention. The hydrophilic mer unit oxyalkylates may be ethylene oxides. Moreover, when the hydrophilic mer units are ethylene oxides, the hydrophobic mer units'may be styrenes. Alternatively, I- 1 1 the hydrophilic mer units may be ethylene oxides and the hydrophobic mer units may be methylmethacrylates. Also, the hydrophilic mer units may be ethylene oxides and the hydrophobic mer units may be buty1methacrylates. When the hydrophilic mer units are methacrylic acids, the hydrophobic mer units may be methylmethacrylates. water-soluble block copolymer may have a molecular weight of from about 1,000 to about 200,000. Preferably, the water-soluble block copolymer may have a molecular weight of from about 5, 000 to about 50,000. The material may further comprise a second watersoluble block copolymer. Moreover, the material may further comprise a polyethylene glycol, a poly(vinyl alcohol), or a polyethylene oxide. The water-soluble block copolymer may be from about 0.1% to about 15% by weight of total ceramic material. Furthermore, the water-soluble block copolymer may be from about 1% to about 5% by weight of total ceramic material.

For the practice of this method, the particles may be produced by granulation and the step of compacting the particles to produce an aggregate structure may be selected from the group consisting of dry pressing and isostatic pressing.

The present invention relates to polymeric binders for preparing ceramic materials. The method can be used to produce fired ceramic materials from ceramic powders. Suitable powders include but are not limited to: aluminum oxide, silicon nitride, aluminum nitride, silicon carbide, silicon oxide, magnesium oxide, lead oxide, zirconium oxide, titanium oxide and neodymium oxide. Aluminum oxide is presently preferred. The 1 11 powder can have a weight-averaged median particle size in the range of a few nanometers to about 1/2 millimeter. Powders having a median size in the range of about 0.5 to about 10 micrometers are preferred.

In one aspect, the ceramic powder is mixed with an aqueous solution containing a polymer to produce a slurry. Preferably, the solution is prepared using deionized water. The slurry may also contain lubricants and surfactants, such as dispersants and anti-foaming agents.

It is also recognized that the properties of a ceramic such as, but not limited to, green density, surface quality or milling characteristics, may be varied as desired by adjusting the ratio of the different monomers in a copolymer, the degree of hydrolysis of a copolymer and the molecular weight of the polymer used in the binder composition.

As used herein, "ceramicmaterials" include ferrites.

The term clays as used herein denotes materials utilized in whiteware manufacture. Examples are kaolin and ball clay among others.

The only limitation on the molecular weight of the block copolymers is that they are of any molecular weight which allows water-solubility.

The following examples are presented to describe preferred embodiments and utilities o the invention and are not meant to limit the invention unless otherwise stated in the claims appended hereto. Examvlg 1 1 A 1 1 12 A copolymer was tested as a binder for alumina particles of the type that are commonly used for producing ceramic materials.

The slip was prepared as follows: 15009 slips were prepared to 80 weight percent alumina powder (99.5% calcined alpha alumina oxide available from Alcan, C90 LSB Alumina) in water using 0.25 weight percent (polymer/powder) of the polymer dispersant. To each slip so prepared, the polymeric treatment to be tested was added, to be a total of 4.0 weight percent (polymer/powder) level. Next, each binder-containing slip was propeller mixed at 800 rpm for one hour. any necessary dilution, deionized water was added to attain the tabulated powder solids level.

The milled slurry was spray dried in a Yamato DL-41 laboratory spray dryer. Dryer operating conditions were: 2500C. air inlet temperature, atomizing air setting of 1.2, slurry feed pump setting, of 5, and drying air feed rate of 0.7 cubic meters per minute. A dry powder was produced which was recovered, screened and stored overnight in a 20 percent relative humidity chamber.

The screened powder was pressed into nine pellets in a Carver laboratory press, three at 5,000 pounds per square inch pressing force, three at 15, 000 pounds per square inch pressing force, and three at 2S,000 pounds per square inch pressing force. The pellets were approximately 28.7 millimeters in diaiieter and 5 to 6 millimeters in height. The dimensions and weights of the pellets were measured and the pellets were crushed to determine the force required to break them.. Diametral compression strength (DCS) for each of the pellets was 1 13 determined from the breaking force and the pellet dimensions. The average diametral compression strength in megapascals for each set of three pellets is presented below in Table I.

Green body diametral compressional strength is important in ceramics applications for the following reasons. The principal function of the binder is to hold the compacted form together after pressing. The method utilized for determination of suitable "green strength" is the diametral compression strength or DCS of a cylindrical section across its diameter. DCS is actually a measure of tensile strength. The unit of measurement of pressure tolerance is the megapascal (Mpa). Typical values for DCS of "green" parts are in the range of 0.3 3.0 Mpa. Therefore, since a higher DCS value indicates a more efficient binder, Table I shows that the polymers of the instant invention are more efficient than a conventional treatment.

Since a greater density is more desirable, the results of Table I illustrate that the polymers of the instant invention are more advantageous in this respect also, as indicated by the higher numbers obtained than in the case of the conventional treatment A.

1 1 ' 1-, 1 14 TABLE I

Comparative Green Body Performance Polymeric Treatment A 1 B 1 -C 1 D 1 E Pressure Green Body Diametrial Compressional Strength Ubs) (Mpa) 5000 0.234 0.340 0.373 0.223 0.181 15000 0.427 0.529 0.613 0.360 0.240 25000 0.464 0.629 0.707 0.438 0.293 Pellet Green Density(glcc) 5000 2.3743 2.4307 2.4161 2. 4-M 677 15000 2.5304 2.5728 2.5665 2.5368 2.5818 25000 2.5537 2.6244 2.6087 2.5932 - - 2.633C0)l A = Conventional polyethylene glycol treatment, PEG 3400, available from Aldrich Chemical Co. of Milwaukee, WI.

B = Polymethylmethacrylate block polyethylene oxide copolymer VP ME 1030, available from Goldschmidt. Chemical Corp. of Hopewell, VA.

C = Polystyrene block polyethylene oxide copolymer VP SE 1030, available from Goldschmidt Chemical Corp. of Hopewell, Va.

D = Polybutylmethacrylate block polyethylene oxide copolymer VPBE 1030, available from Goldschmidt Chemical Corp. of Hopewell, VA.

E = Anionic polystyrene block polyethylene oxide copolymer SE 1010A, available from Goldschmidt Chemical Corp. of Hopewell, VA.

ExgMlg 2 The experimental procedure described in Example 1 was utilized to obtain the results of Table II.

1 TABLE II

Polymeric Treatment A B 1 c 1 D E Pressure Green Body Diametrial Compressional Strength (PSI) (Mpa) 5000 0.1550 0.3405 0.3734 0.2231 0.1806 15000 0.8240 0.5294 0.6133 0.3604 0.2401 25000 1.6760 0.6294 0.7070 0.4375 0.2934 Pressure Pellet Green Density (gICC) (PSI) 5000 1.7187 2.4307 2.4181 2.4023 2.4677 15000 2.1172 2.5728 2.5665 2.5368 2.5818 25000 2.3249 2.6244 2.6087 2.5932 2.6330 A = 4.0 weight percent poly(vinyl acetate) -88% hydrolyzed to poly(vinyl alcohol) available from Air Products of Allentown, PA.

B = Polymethylmethacrylate block polyethylene oxide copolymer VP ME 1030, available from Goldschmidt Chemical Corp. of Hopewell, VA.

Examnle -3 The experimental procedure described in Example I was utilized to obtain the results of Table III. The hydrophobic/hydrophilic block copolymers (D) of this invention were compared to the hydroplibbic block copolymers disclosed in U.S. Patent No. 5,324,770 (C), and the results show the superiority of the block copolymers described herein.

1 16 TABLE Ill

Block Copolymers as Program Additives A 1 B_ c 1 D 1 Pressure Green Body Diametrial Compressional Strength (PSI) (MPa) 5000 0.1550 0.2080 0.3638 0.5670 15000 0.8240 0.5560 1.0156 1.1319 25000 1.6760 0.7030 1.3857 1.4341 Pressure Pellet Green Densit:y(glcc) (PSI) 5000 1.7187 2.1709 2.0984 2.1805 15000 2.1172 2.4054 2.2998 2.3553 1 2.3249 2.4758 2.3880 - _ _ _ 2.4183 A = 4.0 weight percent poly(vinyl acetate) -88W hydrolyzed to poly(vinyl alcohol) available from Air Products of Allentown, PA.

B = 2.0 weight percent poly(vinyl acetate) -88% hydrolyzed to poly(vinyl alcohol) available from Air Products of Allentown, PA and 2.0 weight percent of conventional polyethylene glycol treatment, PEG 3400, available from Aldrich Chemical Co. of Milwaukee, WI C = 2.0 weight percent poly(vinyl acetate) -88% hydrolyzed to poly(vinyl.. al.cohol) available from Air Products of Allentown, PA + 2.0 weight percent copoly(ethylene oxide - propylene oxide) ether linked to (1,2ethandiylnitrilo)tetrakis(propanolI D= 2.0 weight percent poly(vinyl acetate) -88% hydrolyzed to poly(vinyl alcohol) available from Air Products of Allentown, PA + 2.0 weight percent Polybutylmethacrylate block polyethylene oxide copolymer VPBE 1030, available from Goldschmidt Chemical Corp. of Hopewell, VA.

Exami:)1e 4 Brookfield viscosities were determined using standard procedures after the binder polymers were added to the slip. Therefore, Table IV indicates that the embodied polymeric programs, when added to a ceramic slip, result in lower slip viscosity than a conventional treatment program.

In many ceramic manufacturing 17 operations, the efficiency and quality of the process are slip viscosity limited. A lower slip viscosity value than conventional treatment programs may be exploited to increase the weight percent powder per unit slip, thereby improving prodess productivity.

TABLE IV

Resulting Slip Viscosity following 4.0 wt% Binder Addition Polymeric Treatment' Brookfield Viscosity (cP)

A 223 B 28 C 13 D 16 E 43 A = 4.0 weight percent poly(vinyl acetate) -88% hydrolyzed to poly(vinyl alcohol) available from Air Products of Allentown, PA B = Polymethylmethacrylate block polyethylene oxide copolymer VP ME 1030, available from Goldschmidt Chemical Corp. of Hopewell, VA.

D = Polybutylmethacrylate,block polyethylene oxide copolymer VPBE 1030, available from Goldschmidt Chemical Corp. of Hopewell, VA.

= All slips prepared to 61.5 wt% A1203 powder Changes can be made in the composition, operation and arrangement of the method of the present invention described herein without departing from the concept and 18 scope of the invention as defined in the following claims:

1 I- 19

Claims

Claims

An unfired, ceramic precursor material characterized by comprising a mixture of:

a) a ceramic powder selected from the group consisting of aluminum oxide, silicon nitride, aluminum nitride, silicon carbide, silicon oxide, magnesium oxide, lead oxide, zirconium oxide, titanium oxide, steatite, barium titanate, lead zirconate titanate, clays, ferrite, yttrium. oxide, zinc oxide, tungsten carbide, sialon, neodymium oxide and combinations thereof and b) a water soluble block copolymer having hydrophobic and hydrophilic mer units wherein said hydrophilic mer units are selected from the group consisting of oxyalkylates, acrylic acid and methacrylic acid and said hydrophobic mer units are selected from the group consisting of styrene, methylmethacrylate and butylmethacrylate.
2. The material of Claim 1 characterized in that said hydrophilic mer unit oxyalkylates are ethylene oxides.
3. The material of Claim 1 characterized in that said hydrophilic mer units are ethylene oxides and said hydrophobic mer units are individually selected from styrenes, methylmethacrylates and buty1methacrylates.
4. The material of Claim 1 characterized in that said hydrophilic mer units are methacrylic acids and said hydrophobic mer units are methylmethacrylates.
5. The material of Claim 1 characterized in that said water-soluble block copolymer has a molecular weight of from about 1,000 to about 200,000.
6. The material of Claim 1 characterized by further comprising a second water-soluble block copolymer.
7. The material of Claim 1 characterized by further comprising one of a polyethylene glycol, a poly(vinyl alcohol) and a polyethylene oxide.
8. The material of Claim I characterized in that said water-soluble block copolymer is from about 0.1% to about 15% by weight of total'ceramic material.
9. A method for preparing a ceramic material, characterized by comprising the steps of: a) mixing a ceramic powder with an aqueous solution containing a water-soluble block copolymer to produce a slurry, said water-soluble block copolymer having hydrophobic and hydrophilic mer units wherein said hydrophilic mer units are selected from the group consisting of oxyalkylates and methacrylic acid and said hydrophobic mer units are selected from the group consisting of styrene, methylmethacrylate and butylmethacrylate. b) drying the slurry by a process selected from the group consisting of filter pressing, fluidized bed spray drying, spray drying and tape casting to produce particles which include said block copolymer; c) compacting the particles by a process selected from the group consisting of dry pressing, extrusion, isostatic pressing, jiggering and slip casting to produce an aggregate structure; and d) heating the aggregate structure to produce a fired ceramic material.

21
10. The method of Claim 9 characterized in that the particles are produced by granulation and the step of compacting the particles to produce an aggregate structure is selected from the group consisting of dry pressing and isostatic pressing.
11. The method of Claim 9 characterized in that said hydrophilic mer unit oxyalkylates are ethylene oxides.
12. The method of Claim 9 characterized in that said hydrophilic mer units are ethylene oxides and said hydrophobic mer units are selected from styrenes, methylmethacrylates and butylmethacrylates.
13. The method of Claim 9 characterized in that said hydrophilic mer units are methacrylic acids and said hydrophobic mer units are methylmethacrylates.
14. The method of Claim 9 characterized in that said water-soluble block copolymer has a molecular weight of from about 1,000 to about 200,000.
15. The method of Claim 9 characterized by further comprising a second water-soluble block copolymer.
16. The method of Claim 9 characterized by further comprising one of a polyethylene glycol, a poly(vinyl alcohol) and a polyethylene oxide.
17. The method of Claim 9 characterized in that said water-soluble block copolymer is from about 0.1% to about 15% by weight of the total ceramic material.
18. An unfired, ceramic precursor material substantially as herein described in the accompanying examples.
19. A method for preparing a ceramic material substantially as herein described in the accompanying examples.