US 5,508,236 A · Ceramic glass composition

Abstract

An amorphous ceramic glass composition having a density greater than about 2.1 g/cm.sup.3 comprises: between about 35 and 55% by weight SiO.sub.2 ; between about 18 and 28% by weight Al.sub.2 O.sub.3 ; between about 1 and 5% by weight CaO; between about 7 and 14% by weight MgO; between about 0.5 and 5% by weight TiO.sub.2 ; between about 0.4 and 3% by weight B.sub.2 O.sub.3 ; and greater than 0 and up to about 1% by weight P.sub.2 O.sub.5. A convenient source of raw materials is a mixture of coal ash waste, borax (or boric acid) manufacturing plant waste, and titanium pigment waste. The ceramic glass is formed from an intermediate ceramic mixture which is subjected to a heat treatment. The intermediate ceramic mixture is formed by heating a mixture containing SiO.sub.2, Al.sub.2 O.sub.3, CaO, MgO, TiO.sub.2, B.sub.2 O.sub.3, and Na.sub.4 P.sub.2 O.sub.7 to a temperature between about 1400.degree. and 1600.degree. C.; cooling the mixture at a controlled rate between about 15.degree. C. and about 30.degree. C. to solidify it; annealing the mixture at a temperature between about 600.degree. and 670.degree. C. in an atmosphere containing oxygen; and cooling the mixture to a temperature less than about 400.degree. C. at a cooling rate between about 15.degree. and 30.degree. C. per hour. The intermediate ceramic mixture is first heated to a temperature of between about 850.degree. and 1000.degree. C. at a heating rate of between about 1.degree. and 2.degree. C. per minute, and then sintered at a temperature between 850.degree. to 1000.degree. C. for a time period sufficient to increase its density to at least about 2.1 g/cm.sup.3.

Claims33

Dependent claims

A process for producing an amorphous ceramic glass having a density greater than about 2.1 g/cm.sup.3, said process comprising the steps of:

(a) forming an intermediate ceramic mixture comprising SiO.sub.2, Al.sub.2 O.sub.3, CaO, MgO, TiO.sub.2, B.sub.2 O.sub.3, and P.sub.2 O.sub.5, wherein said step of forming an intermediate ceramic mixture comprises the steps of:
(a1) providing a process mixture comprising SiO.sub.2, Al.sub.2 O.sub.3, CaO, MgO, TiO.sub.2, B.sub.2 O.sub.3, and Na.sub.4 P.sub.2 O.sub.7 ;
(a2) heating said process mixture to a first intermediate forming temperature between about 1400.degree. and 1600.degree. C.;
(a3) cooling said process mixture from said first intermediate forming temperature at a cooling rate between about 15.degree. and about 30.degree. C. per hour to a second intermediate forming temperature sufficient to solidify said process mixture;
(a4) annealing said process mixture, following said step of cooling from said first intermediate forming temperature, at an annealing temperature between about 600.degree. and 670.degree. C. in an atmosphere containing oxygen and for a time period greater than about 3.5 hours;
and
(a5) cooling said process mixture from said annealing temperature to a third intermediate forming temperature less than about 400.degree. C. at a cooling rate between about 15.degree. and about 30.degree. C. per hour;
and
(b) subjecting said intermediate ceramic mixture to a heat treatment comprising the steps of:
(b1) heating said intermediate ceramic mixture to a first heat treatment temperature of between about 850.degree. and 1000.degree. C. at a heating rate of between about 1.degree. and 2.degree. C. per minute;
and
(b2) sintering said intermediate ceramic mixture at a sintering temperature between about 850.degree. and 1000.degree. C. for a time period sufficient to increase the density of said ceramic mixture to at least about 2.1 g/cm.sup.3.

9 more elements

A process for producing an amorphous ceramic glass having a density greater than about 2.1 g/cm.sup.3, said process comprising the steps of:

(a) forming an intermediate ceramic mixture comprising SiO.sub.2, Al.sub.2 O.sub.3, CaO, MgO, TiO.sub.2, B.sub.2 O.sub.3, and P.sub.2 O.sub.5, wherein said step of forming an intermediate ceramic mixture comprises the steps of:
(a1) providing a process mixture comprising SiO.sub.2, Al.sub.2 O.sub.3, CaO, MgO, TiO.sub.2, and B.sub.2 O.sub.3 ;
(a2) heating said process mixture to a first intermediate forming temperature between about 1400.degree. and 1600.degree. C.;
(a3) cooling said process mixture from said first intermediate forming temperature at a cooling rate between about 15.degree. and about 30.degree. C. per hour to a second intermediate forming temperature sufficient to solidify said process mixture;
(a4) annealing said process mixture, following said step of cooling from said first intermediate forming temperature, at an annealing temperature between about 600.degree. and 670.degree. C. in an atmosphere containing oxygen and for a time period greater than about 3.5 hours;
(a5) cooling said process mixture from said annealing temperature to a third intermediate forming temperature less than about 400.degree. C. at a cooling rate between about 15.degree. and about 30.degree. C. per hour;
and
(a6) adding Na.sub.4 P.sub.2 O.sub.7 to said process mixture at a fourth intermediate forming temperature greater than about 1300.degree. C. but less than said first intermediate forming temperature;
and
(b) subjecting said intermediate ceramic mixture to a heat treatment comprising the steps of:
(b1) heating said intermediate ceramic mixture to a first heat treatment temperature of between about 850.degree. and 1000.degree. C. at a heating rate of between about 1.degree. and 2.degree. C. per minute;
and
(b2) sintering said intermediate ceramic mixture at a sintering temperature between about 850.degree. and 1000.degree. C. for a time period sufficient to increase the density of said ceramic mixture to at least about 2.1 g/cm.sup.3.

10 more elements

Dependencies are inferred from the claim text.

Ceramic glass composition

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Ceramic glass composition

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Abstract

Claims33