WO1991003433A1 - Method of manufacturing glass-ceramic articles - Google Patents

Method of manufacturing glass-ceramic articles Download PDF

Info

Publication number
WO1991003433A1
WO1991003433A1 PCT/GB1990/001374 GB9001374W WO9103433A1 WO 1991003433 A1 WO1991003433 A1 WO 1991003433A1 GB 9001374 W GB9001374 W GB 9001374W WO 9103433 A1 WO9103433 A1 WO 9103433A1
Authority
WO
WIPO (PCT)
Prior art keywords
glass
glass particles
binder
particles
powdered
Prior art date
Application number
PCT/GB1990/001374
Other languages
French (fr)
Inventor
Keith Russell Mcneill
Original Assignee
Keith Russell Mcneill
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Keith Russell Mcneill filed Critical Keith Russell Mcneill
Publication of WO1991003433A1 publication Critical patent/WO1991003433A1/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/09—Other methods of shaping glass by fusing powdered glass in a shaping mould

Definitions

  • This invention relates to a method of manufacturing glass-ceramic articles and to the articles made by the method.
  • glass-ceramic products may be made by producing a molten glass from glass-forming constituents, or pieces of glass, which include a nucleating agent, forming the molten glass into a desired shape, for example by pressing into slabs, and then re-heating the formed glass shape at a temperature at which crystallisation occurs.
  • a glass-ceramic article may be produced by adhering together particles of powdered glass using a binder, and then heating the glass particle/binder mixture at the liquidus temperature of the glass, i.e. the - 2 -
  • the solid glass particles are heated to the liquidus temperature, while the particles are held in contact with one another, so that maximum crystallisation of the glass will occur, in accordance with my invention, across the boundaries of the contacting glass particles.
  • the glass particles should not be heated significantly above the liquidus temperature of the glass, in particular they must not be heated to a temperature near the softening temperature, because at such temperature the definite shape of a pressed glass-ceramic article will be lost.
  • a method of manufacturing glass-ceramic articles comprising the steps of mixing powdered glass particles with a binder, forming the mixture of powdered glass particles and binder into the shape of a desired article, and heating the shaped mixture at the liquidus temperature of the glass of the glass particles for a time sufficient for the glass particles to crystallise across the boundaries of contacting glass particles and thereby produce a glass-ceramic article of the desired shape.
  • the powdered glass particles are of a size to pass an 850 micron sieve although smaller particle sizes may be used.
  • the finer the powder used the more dense is the final product.
  • smaller particle sizes give rise to shrinkage so that the size of the final article is less than the size of the shaped mixture taken from the mould in which the mixture was shaped. It has been found that, when the method in accordance with the present invention is performed using glass particles of a size to pass a 250 micron sieve, the article shrinks in size by about 10% although the article retains its shape and sharp corners. For smaller particle sizes the degree of shrinkage increases and for particle sizes of the order of 10 microns the shaped mixture will shrink by about 30% in size, although the desired shape is retained.
  • the final articles are, in all cases, glass-ceramic articles of considerable strength and of high resistance to abrasion.
  • the binder used may be an organic binder which is destroyed during the heat treatment.
  • the process in accordance with the present invention has particular application in forming glass-ceramic articles from a glass frit and more specifically from glass frits containing heavy metals prepared as described in my published International Patent Application No. WO 90/09211.
  • German D.E.V.S. 4 When subjected to the internationally accepted standard test for leaching of heavy metals, German D.E.V.S. 4, the glass frit was shown to be acceptable for use as a product.
  • this glass frit may be used as such in products, for example in concrete, as an aggregate, in road foundation, or as an asphalt filler, it is desirable to have further outlets for this safe waste product which will be produced in very large quantities because of the large quantities of refuse which have to be incinerated in modern industrial countries.
  • the toxic waste resulting from incineration of industrial or domestic refuse includes nucleating agents which are consequently also present in the glass frit product of the aforementioned International Patent Application.
  • This glass frit product may be re-melted in a conventional cold-top furnace and fed via a forehearth to production machines for making the glass into tiles and pipes which are then re-heated to crystallise the glass.
  • These crystallised glasses or slags are then more resistant to abrasion, chemical attack and leaching. They are also strong materials which are not subject to fracture in the way that normal glass products may fracture.
  • the said glass frits are, as a further alternative, used as a raw material in forming glass- ceramic articles by a method in which powdered glass particles are caused to crystallise together at their points of contact by heating at the liquidus temperature of the glass.
  • the powder is then screened to a desired particle size and the screened powder is mixed with a binder to enable it to hold a shape prior to and during firing.
  • the binder may be either an organic binder such as ethanol, starch, lignates or isopropanol, or an inorganic binder such as aluminium chloride, a phosphate or ethylsilicate.
  • the powder/binder mixture After mixing with binder the powder/binder mixture is shaped by any conventional method, such as machine pressing, rolling, vacuum forming or extrusion, and the shaped powder/binder mixture is then heat treated to form a solid product by heating to the liquidus temperature for the glass composition, usually a maximum temperature of the order of 1100°C - 1150°C, and holding the shaped mixture at this temperature for a period of the order of two hours so that a crystalline structure is fully developed by crystallisation across the contacting boundaries of the particles of the glass powder.
  • any conventional method such as machine pressing, rolling, vacuum forming or extrusion
  • the glass frits derived therefrom have varying compositions. However, the glass frits derived from different sources are conveniently put into large heaps from which blended material of approximate known chemical composition may be extracted.
  • ingredients of the batch compositions are themselves waste products, for example the magnesite may be obtained from the steel industry and the sand may be waste from grinding processes.
  • the three glass frits which had melting temperatures of the order of 1350°C, were then each divided into three separate samples and one of each of the three samples was treated by each of the three following processes:
  • the particles were crushed and sieved to extract all particles not passing an 850 micron sieve, the screened particles were mixed with a binder which was aluminium chloride or isopropanol, the particle/binder mixture was machine pressed under a pressure of 100 tons to produce a desired shape and the shaped mixture was fired at 1120°C (the liquidus temperature) for two hours. All three compositions were found to maintain their original shape and size, no shrinkage of the shaped mixture being evident after firing.
  • This process was the same as Process A except that the powdered frit was screened using a 250 micron sieve and only particles passing the 250 micron sieve were mixed with the aluminium chloride or isopropanol binder. After firing, all three compositions retained their shape and sharp corners but shrank by about 107 o .
  • glass crystals have grown across the boundaries of contacting glass particles at a temperature below both the melting temperature and the softening temperature of the glass.
  • the growth of crystals in this way at the liquidus temperature of the glass is a very surprising achievement.
  • Products made by the process of the present invention easily pass the D.E.V.S. 4 test for acceptability against leaching.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Glass Compositions (AREA)

Abstract

Glass ceramic articles of a defined shape, particularly thin products and products with sharp corners, are made by forming the shape of the desired article from a mixture of powdered glass particles and binder, and then heating the shaped mixture at the liquidus temperature of the glass of the glass particles for a time sufficient for the glass particles to crystallise across the boundaries of contacting glass particles.

Description

-4- METHOD OF MANUFACTURING GLASS-CERAMIC ARTICLES
This invention relates to a method of manufacturing glass-ceramic articles and to the articles made by the method.
It is well known that glass-ceramic products may be made by producing a molten glass from glass-forming constituents, or pieces of glass, which include a nucleating agent, forming the molten glass into a desired shape, for example by pressing into slabs, and then re-heating the formed glass shape at a temperature at which crystallisation occurs.
However the products obtained in this way always tend to have round edges as a result of the surface tension effect in the molten glass. Also it is difficult to form thin products and very difficult if not impossible to form a thin product having sharp corners.
Hitherto it has been thought that, when making a glass-ceramic article from discrete pieces of glass, it is necessary first to heat the glass particles to the melting temperature of the glass.
I have now made the surprising discovery that a glass-ceramic article may be produced by adhering together particles of powdered glass using a binder, and then heating the glass particle/binder mixture at the liquidus temperature of the glass, i.e. the - 2 -
temperature at which, when a molten mass of that glads is cooled, the first crystals will appear. In the method of my invention, however, the solid glass particles are heated to the liquidus temperature, while the particles are held in contact with one another, so that maximum crystallisation of the glass will occur, in accordance with my invention, across the boundaries of the contacting glass particles. The glass particles should not be heated significantly above the liquidus temperature of the glass, in particular they must not be heated to a temperature near the softening temperature, because at such temperature the definite shape of a pressed glass-ceramic article will be lost.
In accordance with the present invention therefore there is provided a method of manufacturing glass-ceramic articles comprising the steps of mixing powdered glass particles with a binder, forming the mixture of powdered glass particles and binder into the shape of a desired article, and heating the shaped mixture at the liquidus temperature of the glass of the glass particles for a time sufficient for the glass particles to crystallise across the boundaries of contacting glass particles and thereby produce a glass-ceramic article of the desired shape.
By use of the method of the present invention, exact shapes can be made uninhibited by the tendency of molten glass to form round edges. In addition the method enables a thinner product to be made than was possible by prior art processes and, in particular, the method in accordance with the present invention enables the production of thin products with sharp corners.
Preferably the powdered glass particles are of a size to pass an 850 micron sieve although smaller particle sizes may be used. The finer the powder used, the more dense is the final product. However smaller particle sizes give rise to shrinkage so that the size of the final article is less than the size of the shaped mixture taken from the mould in which the mixture was shaped. It has been found that, when the method in accordance with the present invention is performed using glass particles of a size to pass a 250 micron sieve, the article shrinks in size by about 10% although the article retains its shape and sharp corners. For smaller particle sizes the degree of shrinkage increases and for particle sizes of the order of 10 microns the shaped mixture will shrink by about 30% in size, although the desired shape is retained. The final articles are, in all cases, glass-ceramic articles of considerable strength and of high resistance to abrasion.
The binder used may be an organic binder which is destroyed during the heat treatment.
The process in accordance with the present invention has particular application in forming glass-ceramic articles from a glass frit and more specifically from glass frits containing heavy metals prepared as described in my published International Patent Application No. WO 90/09211.
In the said International Patent Application I have described a method of treating toxic waste resulting from the incineration of industrial or domestic refuse in order to render the material harmless by forming it into a glass without releasing volatilised heavy metals and heavy metal compounds into the atmosphere. However in order to prevent volatilisation of the heavy metals from the molten glass when the molten glass is removed from the furnace, the molten glass must be quenched as quickly as possible by pouring it fnto water within an enclosed space from which volatilised metals and heavy metal compounds cannot escape. A method and apparatus for achieving this is particularly described in my aforementioned International Patent Application, and the resulting product is a glass frit.
When subjected to the internationally accepted standard test for leaching of heavy metals, German D.E.V.S. 4, the glass frit was shown to be acceptable for use as a product.
Although this glass frit may be used as such in products, for example in concrete, as an aggregate, in road foundation, or as an asphalt filler, it is desirable to have further outlets for this safe waste product which will be produced in very large quantities because of the large quantities of refuse which have to be incinerated in modern industrial countries.
The toxic waste resulting from incineration of industrial or domestic refuse includes nucleating agents which are consequently also present in the glass frit product of the aforementioned International Patent Application. This glass frit product may be re-melted in a conventional cold-top furnace and fed via a forehearth to production machines for making the glass into tiles and pipes which are then re-heated to crystallise the glass. These crystallised glasses or slags are then more resistant to abrasion, chemical attack and leaching. They are also strong materials which are not subject to fracture in the way that normal glass products may fracture.
In accordance with the invention of the present application, the said glass frits are, as a further alternative, used as a raw material in forming glass- ceramic articles by a method in which powdered glass particles are caused to crystallise together at their points of contact by heating at the liquidus temperature of the glass.
The present invention will be further understood from the following detailed description. Glass frit obtained from toxic waste by the method of my published International Patent Application No. WO 90/09211 is crushed to a powder. This powder is treated by a magnet to remove all free iron. Because the toxic wastes used in the method of the said co-pending patent applications usually contain carbon and other reducing agents as well as iron oxides, free iron metal and alloys are produced during melting. While some of this free metal lies on the bottom of the elter and is extracted therefrom, other free metal will be carried into the frit and it is this free metal which must be removed by a magnet.
The powder is then screened to a desired particle size and the screened powder is mixed with a binder to enable it to hold a shape prior to and during firing. The binder may be either an organic binder such as ethanol, starch, lignates or isopropanol, or an inorganic binder such as aluminium chloride, a phosphate or ethylsilicate. After mixing with binder the powder/binder mixture is shaped by any conventional method, such as machine pressing, rolling, vacuum forming or extrusion, and the shaped powder/binder mixture is then heat treated to form a solid product by heating to the liquidus temperature for the glass composition, usually a maximum temperature of the order of 1100°C - 1150°C, and holding the shaped mixture at this temperature for a period of the order of two hours so that a crystalline structure is fully developed by crystallisation across the contacting boundaries of the particles of the glass powder.
Because there are a variety of sources for the toxic waste treated by the method of my aforementioned International Patent Application, the glass frits derived therefrom have varying compositions. However, the glass frits derived from different sources are conveniently put into large heaps from which blended material of approximate known chemical composition may be extracted.
Glass frits were prepared by the method of my said International Patent Application from three batch compositions as follows:-
1 2 3
Toxic Waste Fly Ash 40 pts 21 pts 40 pts
Limestone 50 pts - 15 pts
Magnesite (Mg 0) 4 pts 4 pts 40 pts
Power Station
Fly Ash (P.F.A.) 100 pts 20 pts 100 pts
Sand (Si02) - 20 pts
Residual Lime after
Gas Washing 35 pts
Advantageously most ingredients of the batch compositions are themselves waste products, for example the magnesite may be obtained from the steel industry and the sand may be waste from grinding processes.
The three glass frits, which had melting temperatures of the order of 1350°C, were then each divided into three separate samples and one of each of the three samples was treated by each of the three following processes:
Process A
The particles were crushed and sieved to extract all particles not passing an 850 micron sieve, the screened particles were mixed with a binder which was aluminium chloride or isopropanol, the particle/binder mixture was machine pressed under a pressure of 100 tons to produce a desired shape and the shaped mixture was fired at 1120°C (the liquidus temperature) for two hours. All three compositions were found to maintain their original shape and size, no shrinkage of the shaped mixture being evident after firing.
Process B
This process was the same as Process A except that the powdered frit was screened using a 250 micron sieve and only particles passing the 250 micron sieve were mixed with the aluminium chloride or isopropanol binder. After firing, all three compositions retained their shape and sharp corners but shrank by about 107o.
Process C
This was the same as Process A except that the powdered frits were screened using a 10 micron sieve and the particles passing the 10 micron sieve were mixed with isopropanol as binder. Again all three compositions were found to retain their original shape but they all shrank by about 30%.
The products of all these processes were very dense glass-ceramic products with high resistance to abrasion and high strength.
In all the processes described, glass crystals have grown across the boundaries of contacting glass particles at a temperature below both the melting temperature and the softening temperature of the glass. The growth of crystals in this way at the liquidus temperature of the glass is a very surprising achievement.
Products made by the process of the present invention easily pass the D.E.V.S. 4 test for acceptability against leaching.

Claims

CLAIMS :
1. A method of manufacturing glass-ceramic articles comprising the steps of mixing powdered glass particles with a binder, forming the mixture of powdered glass particles and binder into the shape of the desired article, and heating the shaped mixture at the liquidus temperature of the glass of the glass particles for a time sufficient for the glass particles to crystallise across the boundaries of contacting glass particles and thereby produce a glass-ceramic article of the desired shape.
2. A method according to Claim 1 wherein the powdered glass particles are derived from a glass frit containing heavy metals.
3. A method according to Claim 1 or Claim 2 wherein the powdered glass particles are mixed with an inorganic binder.
4. A method according to Claim 1 or Claim 2 wherein the powdered glass particles are mixed with an organic binder.
5. A method according to any one of the preceding claims wherein the shaped mixture of powdered glass particles and binder is heated at a temperature of the order of 1100°C for a period of two hours.
6. A method according to Claim 5 wherein the shaped mixture is heated at a temperature of 1120°C.
7. Glass-ceramic articles prepared by a method in accordance with any one of the preceding Claims.
PCT/GB1990/001374 1989-09-06 1990-09-06 Method of manufacturing glass-ceramic articles WO1991003433A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8920106.5 1989-09-06
GB8920106A GB2237015A (en) 1989-09-06 1989-09-06 Method of manufacturing glass-ceramic articles

Publications (1)

Publication Number Publication Date
WO1991003433A1 true WO1991003433A1 (en) 1991-03-21

Family

ID=10662602

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1990/001374 WO1991003433A1 (en) 1989-09-06 1990-09-06 Method of manufacturing glass-ceramic articles

Country Status (2)

Country Link
GB (1) GB2237015A (en)
WO (1) WO1991003433A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999019264A1 (en) * 1997-10-11 1999-04-22 Indupart Glaskeramik Stahl- Und Metallbau Gmbh Method for producing building materials similar to natural stone from sintered glasses or sintered glass ceramics
WO2002024606A1 (en) * 2000-09-21 2002-03-28 Esmalglass, S.A. Base material for preparing vitreous or vitrocrystalline parts. method for preparing the base material and method for manufacturing the parts
ES2192904A1 (en) * 2000-07-05 2003-10-16 Casals Juan Jose Limo Ceramic material used in material science comprises a mixture of granulated glass and gypsum
US6825139B2 (en) * 2001-01-08 2004-11-30 Glasscerax Ltd. Poly-crystalline compositions
CN101823841A (en) * 2010-04-17 2010-09-08 山东科技大学 Colored decorating plate made of composite fly ash microcrystalline glass and preparation method thereof

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3450546A (en) * 1966-05-26 1969-06-17 Corning Glass Works Transparent glass-ceramic articles and method for producing
US3942966A (en) * 1972-04-21 1976-03-09 Karl Kristian Kobs Kroyer Methods of preparing ceramic material
DE3701973A1 (en) * 1986-01-23 1987-07-30 Matsushita Electric Works Ltd Sintered glass powder product

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3330892A (en) * 1964-07-24 1967-07-11 Corning Glass Works Molding comminuted nonplastic inorganic material
GB1186570A (en) * 1966-12-20 1970-04-02 Karl Alfred Kappes Method of Making Ceramic Articles and the Product Thereof
GB2182034A (en) * 1985-10-23 1987-05-07 Stc Plc Sintered glass
JPS62191460A (en) * 1986-02-14 1987-08-21 インタ−ナショナル　ビジネス　マシ−ンズ　コ−ポレ−ション Formation of glass/ceramic formed article
GB2198433B (en) * 1986-12-05 1990-11-07 Romain Louis Billiet Improvements in or relating to the removal of organic binding agents from articles moulded from sinterable materials
US4776866A (en) * 1987-04-23 1988-10-11 Corning Glass Works Method for making extruded whisker-reinforced ceramic matrix composites

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3450546A (en) * 1966-05-26 1969-06-17 Corning Glass Works Transparent glass-ceramic articles and method for producing
US3942966A (en) * 1972-04-21 1976-03-09 Karl Kristian Kobs Kroyer Methods of preparing ceramic material
DE3701973A1 (en) * 1986-01-23 1987-07-30 Matsushita Electric Works Ltd Sintered glass powder product

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Patent Abstracts of Japan, Vol 12, No 132, C490, abstract of JP 62-252341, publ 1987-11-04 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999019264A1 (en) * 1997-10-11 1999-04-22 Indupart Glaskeramik Stahl- Und Metallbau Gmbh Method for producing building materials similar to natural stone from sintered glasses or sintered glass ceramics
US6187255B1 (en) 1997-10-11 2001-02-13 Indupart Glaskeramic Stahl - Und Metallbau Gmbh Method for producing building materials
ES2192904A1 (en) * 2000-07-05 2003-10-16 Casals Juan Jose Limo Ceramic material used in material science comprises a mixture of granulated glass and gypsum
WO2002024606A1 (en) * 2000-09-21 2002-03-28 Esmalglass, S.A. Base material for preparing vitreous or vitrocrystalline parts. method for preparing the base material and method for manufacturing the parts
ES2170009A1 (en) * 2000-09-21 2002-07-16 Esmalglass Sa Base material for the preparation of vitreous vitrocrytalline type pieces, process for preparing the base material and method for manufacturing pieces
US6825139B2 (en) * 2001-01-08 2004-11-30 Glasscerax Ltd. Poly-crystalline compositions
CN101823841A (en) * 2010-04-17 2010-09-08 山东科技大学 Colored decorating plate made of composite fly ash microcrystalline glass and preparation method thereof

Also Published As

Publication number Publication date
GB8920106D0 (en) 1989-10-18
GB2237015A (en) 1991-04-24

Similar Documents

Publication Publication Date Title
KR100496664B1 (en) Ceramic composition made from waste materials and method for manufacturing the same
Leroy et al. Production of glass-ceramics from coal ashes
EP0493217B1 (en) Method for converting waste to crystallized glass
AU2020323709B2 (en) Artificial agglomerate stone article comprising synthetic silicate granules
EP3743243A1 (en) Amorphous silica particles and methods of producing amorphous silica particles
BE1024028A1 (en) IMPROVED SNAIL FROM THE PRODUCTION OF NON-FERRO METALS
WO2011036208A1 (en) Method and reactor for treating bulk material containing carbon
WO1991003433A1 (en) Method of manufacturing glass-ceramic articles
SK82595A3 (en) Method of treating and ecological acceptable use of asbestos- -cement products
CN107140838A (en) A kind of method for cooperateing with processing yellow phosphorus furnace slag and chromium slag
EP0726233B1 (en) Process for recycling of refractory material
US4339254A (en) Glass manufacture employing a silicon carbide refining agent
JPH06227853A (en) Body composition for ceramic
JP3552173B2 (en) Manufacturing method of lightweight aggregate using sewage sludge incineration ash
DE19545187A1 (en) Mineral foam granule with core and outer shell
JPH0118027B2 (en)
JPH06134438A (en) Method for treating waste asbestos material and manufacture of ceramic product using the same
KR100202731B1 (en) Method for preparing waste alumium dros
RU2360873C2 (en) Composition for production of pyroceramic composite tiling material and method for its production
KR100905957B1 (en) Artificial silica and method of preparation thereof
WO1995011865A1 (en) Ceramic materials and method of manufacturing such materials
CN105330146A (en) Method for utilizing blast furnace slag to prepare engravable glass ceramics
JPH0531474A (en) Treatment of bauxite residual slag and production of building material formed by using the bauxite residual slag
Shekhovtsov et al. Anorthite-reducing glass-crystalline materials synthesized in plasma
RU2044570C1 (en) Method of grinding the soda-lime glass

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): JP US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB IT LU NL SE