Casting Slip production of Sanitaryware

8/19/2019 Casting Slip production of Sanitaryware

1/31

J E u r o p a i s c h e s

Patentamt

European

Patent

Office

©

Publication

number:

0 0 4 8

5 2 6

Office

europeen

des

brevets

A 2

©

EUROPEAN

PATENT APPLICATION

©

Application

number:

81201048.6

©

Int.

CI.3:

C

03

C

9 /0 0

@

Date of

filing:

18.09.81

©

Priority:

19.09.80

US 188919

©

Applicant:

FERRO CORPORATION

One

Erieview Plaza

Cleveland Ohio 44114(US)

©

Date of

publication

of

application:

31.03.82

Bulletin

82/13

©

Inventor: Votava,

Werner Friedrich

4092 Diana

Drive

©

Designated

Contracting

States:

Broadview

Heights

Ohio

44147(US)

AT BE CH DE IT LI LU

NL SE

@

Representative:

Kooy,

Leendert Willem

et

al,

Octrooibureau

Vriesendorp

&

Gaade Dr.

Kuyperstraat

6

NL-2514 BBThe

Hague(NL)

54)

Vitreous frit

and

fired

sanitary-ware

body.

A

process

for

producing feldspathic sanitary ware

and

the end

product

are

disclosed in which

a

fluxing

amount

of

a

glass

frit

is used in the

ceramic

slip

used

to cast

the

sanitary

ware.

The frit

contains

both

deflocculent oxides

and

floccu-

lent alkaline

earths which

are

leachable from the

frit

when it

is

placed

in the ceramic

slip.

The

deflocculent oxides

counterbalance

the effect of the flocculent

alkaline

earths

to

the

extent

they are respectively

leached

from

the frit

upon

dispersal

in

a

ceramic

slip

and maintain the

slip

at

a

workable

viscosity. Upon

casting

and

firing

the

slip,

the

present

frit

precipitates

fine

crystals

of

diopside having

an

average

particle size of less than one micron which are particularly

useful in

lowering

the

firing

temperature

of

feldspathic

bodies

by promoting

the

required

degree

of vitrification

at

lower

temperatures

than heretofore

possible.


2/31

S a n i t a r y - w a r e

f i x t u r e s , i . e . ,

t o i l e t

bowls,

lava tor ies and the

l ike ,

p a r t i c u l a r l y

the

former,

are

c o n s t r u c t e d o f

a g lazed , h i gh ly

v i t r i f i e d ,

f e l d s p a t h i c b o d y .

The

body

is

u s u a l ly

formed

by

the wel l -known

method

of

s l i p c a s t i n g ,

c a r e f u l l y

and

slowly

d r i e d ,

glazed

and

f i re d t o v i t r i f i c a t i o n

in

a

tunnel kiln a t

a

tempera ture

e q u i v a l e n t

of

Seger

pyrometric cone

9

to

10. The

body

is

normally

r e f e r r e d

to

as

f e l d s p a t h i c

i n d i c a t i n g

tha t

a

s u b s t a n t i a l

p r o p o r t i o n

of the

minera l con ten t o f

the

s l ip

is

feldspar. However, nowadays f e l d s p a t h i c

sand

o r

nepheline syenite can

be

o p t i o n n a l l y

used

as a

p a r t i a l or c o mp le te

replacement

for

the

fe ld s p a r

without

c h a n g in g th i s

g e n e r i c

d e s c r i p t i o n .

Id e a l ly , a n d as

will

be d e s c r ib e d in

more

d e t a i l

h e r e i n a f t e r ,

t h e

cas t ing s l ip ,

as

well as

the

f i n a l ,

f i r e d ,

v i t r i f i e d

body,

mus t

meet

c e r t a in

r i g i d , r h e o l o g i c a l

and

phys ica l

proper ty

s t a n d a r d s .

For example, the v i s co s it y , s p e c i f i c g r a v i t y a n d s t a b i l i t y of t h e

cas t ing

s l ip

should

id e a l ly

remain

cons tan t

over

a p p r e c i a b l e

periods

of

time

as

these fac tors

are

all

c r i t i c a l f ro m

the

s t a n d -

point

of

cas t ing

bodies

having

d e s i r e d w a l l

th ic k n e s s e s , d ry in g

shr inkage ,

e t c .


3/31

The

f i re d

body, ideally,

will be

completely

v i t r i f i e d ,

have

h i g h

s t r e n g t h ,

with

minimum,

though

uniform,

s h r in k a g e o n f i r in g .

In an

e f f o r t

to

e i t h e r ,

or

both,

speed

the

f i r i n g o p e r a t i o n

and

t o

lower

the

f i r i n g

tempera ture ,

any

number

of

body

a d d i t iv e s h a v e

been experimented

with.

For

example,

many

flux ing

m a t e r i a l s

have

been

t r i e d

to

speed

the

body

v i t r i f i c a t i o n

process ,

with

v a r y i n g

degrees

of

success .

However,

such fluxes have

g e n e r a l l y

c r e a t e d

more

problems

than

they

have solved.

That

is ,

speeding

up

the


process poses

no major

problem,

in and of

i t s e l f ;

but

s l ip

i n s t a b i l i t y ,

e x c e s s i v e

shrinkage or

warpage

on drying

or

f i r i n g ,

lower

s t r e n g h t ,

s h o r t


range,

e t c . ,

have

u s u a l ly

accompanied

the

u t i l i z a t i o n

of

c o n v e n t io n a l

body

fluxes

used here tofore .

By

way

of

e x p l a n a t i o n ,

shor t


range

r e f e r s

to

the

te mp e ra tu re s p re a d ,

wi th in

a

commercial

k i ln ,

over

which the

required degree

o f

v i t r i f i c a t i o n w il l both

occur

and be

sus ta ined wi thout

s lumping

and/or

c r y s t a l l i z a t i o n

( d e v i t r i f i c a t i o n ) .

Th e re fo re ,

while

a


range

would be

o f l i t t l e

or no

s i g n i f i c a n c e

in

a

small

t e s t

bar,

f i r e d

under

c a r e f u l l y

c o n t r o l l e d

l a b o r a t o r y

c o n d i t io n s ,

i t

i s v i t a l

to

success fu l manufac ture

o f

s a n i t a r y - w a r e

products

on

a

commercial scale in

a

c o n t i n u o u s

p ro d u c t io n

tunnel kiln .

Thus,

if

a san i t a ry- ware

body

r e a c h e s

v i t r i f i c a t i o n at

precisely cone

10

down,

while

at

cone

9 it

is

n o t

v i t r i f i e d ,

whereas

at

cone

11

it has

begun

to

slump,

t h e

p ro d u c t io n

problems

become

re a d i ly

apparen t

because there is

no

p r a c t i c a l

way

to achieve tempera ture c o n t ro l at prec ise ly cone 10

throughout

the

cross

sec t ion

of the

firing zone

of

a production

k i l n .

A

r e l a t e d

problem

in

c a s t in g s a n i t a ry

ware

from

a

ceramic

s l ip

i n

which

a glass

f r i t

serves as

a

flux is

that the f ri t ten ds to be

somewhat

so lub le .

Components

leached from

the

f r i t , n o ta b ly

t h e


4/31

a l k a l i n e

ear ths , ac t

as

f l o c c u l e n t s

and

can

s u f f i c i e n t l y

r a i s e

the

v i s o c i t y

of the

s l ip

to

make

it unworkable.

In

fa c t ,

some

s l ips may even v i r tu a l l y s o l id i fy . Moreover, th is f l o c c u l a t i o n t o

an

unworkable

v iscos i ty can

often

take

place

in

a r e l a t i v e l y

short

time.

Also,

s i n t e r i n g

of the

cast

ceramic

s l ip

leaves

a

c e r t a i n

amount of

unreac ted

a l k a l i n e

earth in the s intered

p r o d u c t .

This

l ikewise

has

an

u n d e s i r a b l e

f l o c c u l a t i n g

e f f e c t

on

the

s l i p .

The

f i e l d

of this

invent ion

d e a l s p r i m a r i l y

with

the

p r o d u c t i o n

of

sanitary-ware body

a d d i t i v e s

designed

to lower the

p r o d u c t i o n

f i r i n g

tempera ture

of

a san it ar y- war e body,

while at

the

same

t ime

p re s e rv in g

all the

required

c h a r a c t e r i s t i c s

of

said

body

in both

the

s l ip

stage, as

well

as

in the

f i n a l ,

f i r e d

produc t .

F u r t h e r ,

the invent ion

includes

a c o u n te rb a l a n c in g

o f f lo c c u le n t s

l e a c h e d

by

the

s l ip

f ro m f lu x in g

frit and

a

r e s u l t i n g

maintance

of

a

workable

v i s c o s i t y

of

the

s l i p .

The

u t i l i z a t i o n

o f e i th e r wo l la s to n i t e

(Ca0.Si02)

o r d i o p s i d e

(CaO.MgO.2

SiO )

as

an

addi t ive for

ceramic bodies is disclosed

by H.G. Kurczyk in a paper e n t i t l e d , Synthe t ic Diopside and

Synthe t ic

W o l l a s t o n i t e -

New

Raw

Ma te r i a l s

for

Ceramics ,

from the

Proceedings

of the 3rd

CIMTEC,

3rd

I n t e r n a t i o n a l

Meeting on

Modern

Ceramics

Technologies

at

Rimin i , I ta ly ,

May

27-31,

1976.

Kurczyk

disc loses the

p o s s i b i l i t y

of

synthes is

of

diopside by

any

number of

means,

inc lud ing

synthesis by

s o l i d - s t a t e

r e a c t i o n ,


from

a

molten

bath,

s i n t e r i n g ,

etc.

Ku rc z y k ' s

p r e f e r r e d

method

apparen t ly

is

the formation

of

diopside

from

dolomite and

ground

quartz

in the

a p p ro p r ia te

molecu la r ra t ion

by

hydrothermal

p re t re a tme n t

and

c a l c i n a t i o n .

However,

d iops ide

produced

b y s in te r in g ,

from

the

s tandpoin t

o f

a d a p t a b i l i t y

to

ceramic

bodies ,

has

a

number

of drawbacks.

F i r s t ,


5/31

the

s i n t e r i n g

process

u t i l i z e s

a rotary

k i ln

opera t ion

s i m i l a r t o

tha t

used

for the

manufacture of

p o r t l a n d

cement c linker.

As

i s

well

known,

it

is

exceedingly

d i f f i c u l t t o

control the

f i r i n g

tempera ture

in

a

ro ta ry

kiln with

any

degree

of

p r e c i s i o n ,

wh e re in

v a r i a t i o n s

in

temperature

may

promote

e i t h e r

a

soft

b u r n ,

r e s u l t i n g

in

a high

percentage

of

u n re a c te d

m a t e r i a l ,

or

cause a

p a r t i a l l y

molten

ba th which so l id i f ies

upon

discharge

from

t h e

s i n t e r i n g

zone,

r e s u l t i n g

in the formation of

a non-uniform,

heavy ,

s l a g - ty p e

coating on

the

c a lc in e r

walls with

a t t e n d a n t u n d e s i r a b l e

i n t e r r u p t i o n s

in the overall

o p e r a t i o n .

Fur thermore , the diopside produced by the method disclosed by

Kurczyk

is

r e l a t i v e l y

large grained

(10 to

30

microns)

which

t e n d s

to

reduce

i t s

e f f e c t i v e n e s s

in

lowering

the

f i r in g t e mp e ra tu re

o f

a


body

and,

as

is well

known,

the

d iops ide

m i n e r a l

c r y s t a l

tends to be

extremely

hard

and

tough, thereby

making

i t

most

d i f f i c u l t

to

mill

and

grind

to

a p a r t i c l e

size small

enough

to

be

e f fe c t iv e ly d i s p e rs e d th ro u g h o u t

a

s a n i t a ry -wa re

body s l ip .

It

has

been found however

th a t ,

if

the

molten bath which

Kurczyk

found

to

be

u n d e s i ra b le ,

is

d e l i b e r a t e l y

created under

c o n t r o l l e d

c o n d i t io n s ,

followed

by

the novel

p ro c e s s in g

steps

h e r e i n a f t e r

s e t

fo r th ,

a

more

economically produced, s upe ri or

form of

d iops ide

i s

achieved,

which

e l imin a te s

a l l

the

d i s a d v a n ta g e s

of

Kurczyk,

w h i l e

provid ing

a

number

of addi t iona l

improvements

t h e r e o v e r .

OBJECTS

It is

t h e r e f o r e

an object

of this

in v e n t io n

to

provide

a

new

and

improved crys ta l l ine form of d i o p s i d e .

It

is

another

objec t

of

th is

invention to

provide a

r e l a t i v e l y

low

tempera ture

glass

matrix from which

fine

grained

diopside

c r y s t a l s

may

be

formed

upon

rehea t ing

said

g lass

to its



6/31

t e m p e r a t u r e .

It is yet another objec t o f t h i s i n v en t i o n to provide d i o p s i d e

p re c u rs o rs

in

glass

s o lu t io n

in

a r e l a t i v e l y

low

melting

t e m p e r a t u r e

g lass ,

which

glass

may

be

re a d i ly

i n c o r p o r a t e d

into

a

ceramic

body,

and

which

glass ,

upon

f i r i n g

of the

body,

wil l

p r e c i p i t a t e

a t l e a s t

some

fine

grained

c r y s t a l l i n e d i o p s i d e ,

un iformly

dispersed

and

formed in situ

throughout

said

body.

It

is

yet

another

objec t

of

th i s

in v e n t io n

to

provide

a

v i t r e o u s

source

of fine

grained

d i o p s i d e c r y s t a l s w h i c h

can

be

e a s i ly

and

re a d i ly

mil led

to

a

s u f f i c i e n t f ineness for

in c o rp o ra t io n

into

a


ceramic

body.

It is another

objec t

to

ach ieve a

process

for

m a n u f a c t u r i n g t h e

r e l a t i v e l y

low

tempera ture

glass

of

t h i s i n v e n t i o n .

It

is

a

f u r t h e r

objec t

to counte rac t

f l o c c u l e n t s

leached

by

a s l i p

from

glass

and

prevent

t h e i r

in c re a s in g

the

v i s c o s i t y

of the

s l i p

to

unworkable

v a l u e s .

And

f i n a l l y ,

it

is

an object

to

provide a

new

and

improved,

s a n i t a ry -wa re

body, as

we l l a s

provide

the

process

for

a c h i e v i n g

same.

SUMMARY

OF

THE INVENTION

The

presen t

invention reduces the

f i r in g t e mp e ra tu re s

of

v i t r e o u s

and semi-vitreous

bodies

c o mp r i s in g fe ld s p a th ic

ma te r i a l s ,

w h i l e

maintai ning a s u i t a b le f i r i n g range and o t h e r p h y s i c a l p r o p e r t i e s

of

such

material. As

a

r e s u l t ,

the re is subs tan t ia l fue l

s a v i n g s

with

increased

p r o d u c t i v i t y .

By

s u b s t a n t i a l l y b a l a n c i n g

t h e

deflocculent oxides and

f l o c c u l e n t

a l k a l i n e

e a r t h

e x t r a c t a b i l i t i e s

from

the

glass

added

to

a

s l ip ,

i ts

v i s o c i ty c a n


7/31

be

maintained

wi th in wo rk a b le l imi t s .

In one

form of the

invent ion ,

the

glass

hereof

in the

form

of

a

finely ground

f r i t

is

mexed with the

ceramic

ma te r i a l

to

b e f i r e d

to

form

a


body.

The

f r i t c o n ta in s

i n s o l u t i o n

q u a n t i t i e s

of

the

oxides

conta ined

in

d iops ide ,

namely

MgO, CaO,

and

Si02,

and is

so

formula ted

th a t

when

heated

above

a

c e r t a i n

tempera ture

(as

during

the

f i r i n g

of the

ceramic

body)

fine

g r a i n e d

diopside

c r y s t a l s p r e c i p i t a t e

out

and

act

as

a flux,

lowering

t h e


s u b s t a n t i a l l y ,

for

example,

at

l e a s t

t h r e e

Seger

cones as compared

to

the


tha t

would

b e

required

without the d io p s id e c ry s ta l s . The frit c o n t a i n s l e a c h a b l e

d e f l o c c u l e n t

oxides which counterbalance

any

f l o c c u l e n t a l k a l i n e

earths

leached therefrom and

prevent th ickening

of

the

s l ip

to

an

unworkable

v i s o c i t y .

DESCRIPTION

OF

THE

PREFERRED EMBODIMENTS

In

accordance

with

the

p re s e n t

in v e n t io n ,

a

glass

f r i t

c o n t a i n i n g

in

s o lu t io n

the

diops ide

p re c u rs o rs

CaO,

MgO,

and

SiO2,

i n

in c o rp o ra te d

with

a

ceramic mate r ia l tha t

is

shaped

into

a

body

and

fired to

achieve the desired

degree

of

v i t r i f i c a t i o n .

Du r in g

the f i r ing , d iops ide

forms

from the

p re c u rs o rs

and

p r e c i p i t a t e s a s

fine

c r y s t a l s

which

serve as

a

flux.

The

c r y s t a l l i n e ,

f l u x i n g

diops ide

s u b s t a n t i a l l y

lowers

the

f i r in g t e mp e ra tu re re q u i re d

o f

the

ceramic

m a t e r i a l

in

forming

the

san i ta ry-ware or

other

body .

Considering

these

components

in

g re a te r

d e t a i l ,

the

d i o p s i d e

p re c u rs o rs ,

CaO,

MgO,

and

Si02,

should

comprise

at

least 35%

by

weight of the g la s s . For example, such a glass may comprise i n

weight

percen t

a b o u t ;


8/31

t h e a d d i t i v e

being

s e l e c t e d

from

one or

more

of

the

f o l l o w i n g

in

approximate ly

the

percen t

in d ic a te d

based

on

the

to ta l

w e i g h t

of the

g l a s s :

the

fluorine when

p r e s e n t

being

introduced into the batch

a s

a

f luor ide of

at

l e a s t

one

metal

of

the

c o m p o s i t i o n .

A

more

d e s i ra b le

compos i t ion

comprises

in

weight

percen t

a b o u t :

the additive

being

selected from

one or more

of the

fo l lowing

i n

approximately

the

p e rc e n t

indicated based

on

the

t o t a l

weight

o f

the

g l a s s :

A

p re fe r re d

compos i t iona l

range

and

a pre f e rre d

composition

f o r

the

glass

conta in ing

the

diops ide

precursors

are

in

we ig h t p e rc e n t

about :


9/31

It

will

be

a p p re c ia te d

tha t

these

compos i t ions

c o n s t i t u t e m e t a l

oxide

ana lyses

of the

smelted

glass .

The

c o r re s p o n d in g

b a t h

ma te r i a l s

may

con s t i tu t e those mat e r i a ls which

on

smelting

and

cooling yield

the oxide

a n a ly s i s .

For

example,

the

presen t

g l a s s e s

can

be

smelted from dolomite

and

l i t h o s p a r

in

a weight

r a t i o o f

about

76:24

to

11:89,

res pec t i ve l y . Whit ing can

be

s u b s t i t u t e d

f o r

a

r e l a t i v e l y

small

por t ion

of the

dolomite ,

and

any

of the other

i n g r e d i e n t s

o p t i o n a l l y

included

can

be

added

to

the

batch,

e i t h e r

in

the

oxide

or

s a l t

form

or

in

a

form

which

reduces

to

the metal

oxide

or

fluoride form

on

smelting.

For

example, spodumene,

l e p i d o l i t e ,

and the like

may

c o n s t i t u t e

p a r t

of

the ba tch

f o r m u l a t i o n .

Compositions

with the

ranges

d i s c lo s e d

melt

at

t e m p e r a t u r e s

approximat ing

about

2600°F

to

about

2750°F.

The

melt

may

be

f r i t t e d

in

any

convenient

manner,

such

as

by quenching

the melt

i n

water

or

pass ing

it between

f r i t t i n g

r o l l e r s . The f r i t

so

o b t a i n e d

is

convent iona l ly ground pr ior

to

use.

As

an example,

the

f r i t

may

be

ground

so

tha t

about 95%

passes

through

325

mesh, U.S.

Standard Sieve. X-ray examination shows tha t the f r i t i s t o t a l l y

v i t r e o u s

or

nearly so.

A

glass

of

the

type

descr ibed ,

c o n ta in in g

the

diops ide

p r e c u r s o r s ,

is

in c o rp o ra te d

with

s u i t a b le c e ra mic ma te r i a l s

tha t

is

adapted


10/31

to

form

s a n i t a r y

ware,

and the

mixture is then

shaped

into

a

body,

as by

s l ip

c a s t i n g .

The

body

is

then fired

to

y ie ld

the

s a n i t a r y

ware.

As

d e s c r ib e d

more

fu l ly

h e r e i n a f t e r ,

the

p re s e n t

glass

d o e s

not

s i g n i f i c a n t l y

affec t the

cas t ing

p r o p e r t i e s

of

the

s l ip ,

and

i t s

v i s c o s i t y

may

be

c o n t r o l l e d

by providing

counte rac t ing or

c o u n t e r -

balancing

le a c h a b le

amounts

o f d e f lo c c u le n t .

In

c o n t r a s t

o t h e r

commercial

g la s s e s

can markedly

a f fe c t

s l ip

p r o p e r t i e s

in

a

d e l e t e r i o u s

way.

A

p re fe r re d

ceramic

ma te r i a l

used

to form

the

body

is

a f e l d s p a t h i c

one, tha t is, bodies in which a s u b s t a n t i a l p o r t io n of the minera l

content

is

f e l d s p a r .

In

accordance

with the

presen t

in v e n t io n ,

the

tempera ture

of

f i r i n g

is

lower

by

a t leas t

three

Seger cones

than would be

r e q u i r e d

without

the

presence

of

the

i n s t a n t

g la s s e s .

Any addition

of

a

presen t

glass

e f f e c t s

some

reduc t ion

in

the

f i r i n g

tempera ture

o f

the

ceramic

body.

Amounts

as

l i t t l e

as

0.1%

by weight

of

the

body

to

as

much

as

10%

or more

a r e u s e f u l .

However,

the

p r e f e r r e d

r a n g e

of

the

glass

is about

3%

to

about

5%

by

weight

of

the ceramic

body.

Upon

fi r ing a

ceramic

body

conta in ing

a

p re s e n t

g lass ,

the

d e s c r i b e d

precursors

p r e c i p i t a t e

in situ

in the

body as

very

fine

c r y s t a l s

of

d iops ide .

In

one

in s ta n c e ,

i t

was

observed that the

g l a s s

c r y s t a l l i z e d

at about

16520F

(9000C),

although

th i s

tempera ture

i s

not

c r i t i c a l .

Upon

such

c r y s t a l l i z a t i o n ,

at

l e a s t

about

50%

by

weight

of

th e in s ta n t

glass

converts

to

c r y s t a l l i n e

d iops ide ,

t h e

balance forming a glassy r e s i d u e .

The

c r y s t a l s

formed

are extremely

fine

and

th is

is believed

to

be

quite advantageous.

A


p o r t i o n o f

the

c r y s t a l l i n e d i o p s i d e

formed

has

an

average

p a r t i c l e

size less than

one

micron.

Dio p s id e

formed

in

accordance

with

the

presen t

invent ion is a

b e t t e r

body


11/31

flux

than

synthe t ic d iops ide .

This is

b e l i e v e d

to

be due

a t l e a s t

in

part

to

the fine

grained

nature

of

the

d iops ide

formed

which

leads to fas te r

d i s s o l u t i o n

in the subsequent f lux ing ac t ion . T h i s

fluxing

action

accorded

by

the

p re s e n t

g la s s e s

is

so

e f f e c t i v e

t h a t

i t

lowers

the

required

f i r in g t e mp e ra tu re s

at

l e a s t

three

Seger

pyrometr ic

cones

and

t y p i c a l l y

from

cone

10

to

12

to

cone

5

to

6,

wh i le s t i l l

r e t a i n i n g a 'g oo d, s u f f i c i e n t l y

wide

f i r i n g

t e m p e r a t u r e

and

reducing

warpage .

X-ray

d i f f r a c t i o n

results from

f i re d

mix tu re s

of the

p r e s e n t g l a s s e s

with


bod ies show th at

no new

compounds are

formed

other than the d io p s id e c ry s ta l s . A p r o g r e s s i v e

glass

f o r m a t i o n

appears

to

take

place

by

fusion

of the


matrix

and

a s s i m i l a t i o n

of the

d i o p s i d e c r y s t a l s .

For

purposes

of

comparing

th e b e n e f i t s

and

degree

of

u t i l i t y

of

t h e

presen t

invention with that which has been

p r a c t i c e d

in the

p a s t ,

the

following

is

exemplary

of

a

c o n v e n t io n a l

cone

9-10

body

composition

used

h e r e t o f o r e :

The composition

of the

fe ld s p a r wa s e s s e n t i a l ly KNaO . A l 2 O 3 .

6SiO2.

The

sodium s i l ica te

was

added

as a

50%

aqueous

s o lu t io n

s u f f i c i e n t

to

achieve

an

i n i t i a l

s l ip

v i s c o s i t y

as

measured

on

a

B r o o k f i e l d

v i s c o s ime te r

on

e i th e r

a

≠≠

3

or a

≠≠

5

spindle

at

10

RPM.


12/31

The

foregoing sanitary-ware body composition

was

cast

into

t e s t

bars

having

the

dimensions

one cm. by

one

cm.

by

10

cm.,

and

measured for

f i r i n g

and

t o t a l

shr inkage ,

a d s o rp t io n

and

warpage ,

the

r e s u l t s ,

from

cone

8

to

cone

11,

tabulated below in

Table 1.

The

foregoing phys ica l

c h a r a c t e r i s t i c s ,

as

well

as

those which

are

re p o r te d

in the

fo l lo win g t a b le s ,

were

a r r iv e d

at

as

f o l l o w s :

Percen tage

F i r in g Sh r in k a g e :

This

was

determined

as

being

the d i f fe rence

between dried

l e n g t h

and

f i re d

length ,

divided

by

the dried

length

and

m u l t i p l i e d b y

100 to provide the ind ica ted p e r c e n t a g e .

In

th i s

regard

i t

should

be noted

th a t ,

at

l e a s t

t h e o r e t i c a l l y

and

p r e d i c t a b l y ,

the lower the

shr inkage ,

g e n e ra l ly

t h e b e t t e r .

However,

because

e x i s t i n g

commercial molds have

been

designed

t o

provide

a

f i n i s h e d a r t i c l e

in

contempla t ion

of 10%

shrinkage ,

t h e

body as

descr ibed

b e lo w, u t i l i z in g

the

i n s t a n t

in v e n t io n ,

has

been

compounded

to

provide approximate ly

10%

shrinkage

to

e l i m i n a t e

the

need for extensive

commercial mold

redes ign

at

th is

t i m e .

Percen tage

Ab s o rp t io n :

Percen tage

absorp t ion

was

obta ined

using

ASTM

test method C373-72.


13/31

An

a b s o rp t io n

of

approximate ly

0.5%

or

less

is

g e n e r a l l y

n e c e s s a r y

to assure a

s u f f i c i e n t l y

v i t r i f i e d

body.

Cons ider ing

the

use

t o

which

sanitary ware

is

put,

and further

c o n s id e r in g

that not

e v e ry

square

inch

of surface

exposed

to

water

will

be

glazed,

the

need

for

a

high degree

of v i t r i f i c a t i o n w il l

be

r e a d i l y

a p p a r e n t .

Warpage:

Warpage

was

measured

on

t e s t

bars

supported

over a

f ive

inch

span

during

f i r i n g ,

the

measurement,

a f t e r

cooling

to

room tempera ture ,

taken two

and

one

ha lf

inches from either

support

at the

m i d p o i n t ,

using a

depth

gauge,

the

droop

being

taken

as a

measure

of

t h e

degree of warpage, re p o r te d in inches .

A

warpage

of 20

mils ,

s l ightly more or

less ,

is

cons idered to be

about

the

norm,

and would be

expected

to

produce commerc ia l ly

acceptable ware.

Anything materia lly beyond

20

mils would

l i k e l y

r e s u l t

in

commerc ia l ly unacceptab le

f i x t u r e s .

Percent

Total

S h r i n k a g e :

This

f igure

was

de te rmined

e s s e n t i a l l y

the

same as firing shrinkage,

except

the in i t ia l measurement

was

made while the

t e s t

bar

was

s t i l l

in

the

p l a s t i c

s t a t e , p r i o r

to

d r y i n g .

Modulus of

Ru p tu re :

Modulus of

Rupture

was

c a l c u l a t e d

using

the s tandard formula :

wherein

M

=

the modulus

of

ru p tu re

in

pounds

per

square

i n c h ;

P

=

the

break ing

load,

in

pounds;

1

=

the dis tance

between the knife

edges

in

i n c h e s ;

b

=

the breadth of

the

bar in

i n c h e s ;

d =

the

depth

of

the

bar,

in inches .


14/31

Modulus of

ru p tu re

of

course

is

a

measure

of

the

s t re n g th

o f

the

f i r e d

body.

Commercial

s a n i t a ry

ware

under

o u r e x p e r ime n ta l

c o n d i t io n s

y ie ld s

modulus of

ru p tu re

values

of

about

7000

pounds

per

square

inch,

and

th is

may

be

compared

with

exper imenta l

body

values

shown

in

Table

IV.

To

c o mp a ra t iv e ly

demons tra te the e ffec t iveness

of

t h e i n s t a n t

invent ion

in

s u b s ta n t i a l ly lo we r in g

both

the

f i r i n g

t e m p e r a t u r e ,

as

well

as

the

time of

f i r i n g

of

a sanitary-ware body,

t h e

following cone

5-6

base

body

composition was

used :

It

wi l l

be

seen

th a t ,

but

for

a

s l i g h t

reduc t ion

in

Si02,

t h e

above

base

body

composition

is

e s s e n t i a l l y

the

same as

t h a t s e t

for th above for cone 9-10 p r o c e s s i n g .

Using

the

cone

5-6

base

body

composition

as

j u s t g i v e n

as

t h e

fe ldspa th ic body ,

there is

t a b u l a t e d

in the

following

Table II

the

components

of

a

se r ies

of

s a n i t a ry - wa re s l ip s wh ic h we re

weighed

and

mixed with various

a u x i l i a r y

components

added

as

n o t e d

and

the

v i s c o s i t y ,

as

with

the

cone

9

body, adjusted

with

a

50%

s o lu t io n

of

Na2SiO3.


15/31

Re fe r r in g in more d e t a i l to the fluxes l i s t ed in Table II, Flux A

was

a

high

calcium,

a lu min a s i l i c a te

glass

having

a

r e f r a c t i v e

index

of

1.65.

Flux

B

was a glass

flux

purchased

on

the

open

marke t

and

is unders tood

to

comprise ground

window

glass

having a coa t ing

to

make the

glass

p a r t i c l e s mo re

water

r e s i s t a n t .

Flux C

was a

g lass

of the

p re s e n t

invention and

comprised

in

weight

p e r c e n t :


16/31


17/31

Body

composition

14

in Tables

II I

and

IV

re p re s e n t s

the

cone

9-10

body

compos i t ion

p re v io u s ly

given.

The

sodium s i l ica te

was

added

to

the

s l ip s

to

d e f l o c c u l a t e

the

clay.

The

B r o o k f i e l d v i s c o s i t i e s

were

determined

with

No.

3 Spindle

at

10

rpm.

except

for

Body


18/31

Compositions

3

and

8

where

No.

5 Sp in dl e was

u s e d wi th a d d i t io n a l

sodium

s i l i c a t e

as

in d ic a te d

by

a

lower

entry

line for

la te

a g i n g

per iods

for

those

compositions .

S i m i l a r l y ,

an

added

amount

o f

sodium

s i l i c a t e

was

used

for

Body

Composition

6

for

t e s t i n g

at

t h e

aging

leve l

of

two

days

and

more.

Re fe r r in g

to

Table

III, Body

Compositions

1

and

14

show

the

normal

gradua l

re d u c t io n

of

v i s c o s i t y

with

age.

Body

Compositions

2

a n d 3

with

Flux

A

required more

sodium

s i l i c a t e for i n i t i a l

d e f l o c c u l a t i o n

than did

Body Composition

6

c o n ta in in g

a

flux of the

p re s e n t

in v e n t io n .

Body Compositions

c o n ta in in g

Flux

A

also showed

a th ickening tendency on aging. Simflarly, the s y n t h e t i c d i o p s i d e

re q u i re d

more

sodium s i l i c a t e for in i t i a l d e f l o c c u l a t io n tha n th e

p re s e n t

Body Composition

6,

and

the

v i s c o s i t y

of the former

increased wi th

age.

When

ca lc ined do lomite

was added,

the

s l i p ,

th ickened

to

a

thick

paste

and it

was

not

p o s s ib le

to

d e f l o c c u l a t e

it

(Body

7).

Body Compositions

10, 11,

12

and 13 all

caused

t h e i r

r e s p e c t i v e

s l ip s

to

thicken

to

a

s t i f f

paste

a f t e r

one day.

C r i t i c a l

data from the

s ta n d p o in t

of

the

f in i s h e d ,

f i r e d

p i e c e ,

are

set

forth in

Table

IV.

Only

Body Compositions

2,

4,

6

and 7

even

approached

v i t r i f i c a t i o n a t

a

tempera ture

of

cone

6.

Body

Compositions

11,

12

and

13 thickened

very

rap id ly

on aging

and

were

i m p r a c t i c a l

for

use

in

a

c a s t in g s l ip .

Of the

r e m a i n i n g

compos i t ions ,

only Body

Compositions

6

and 7

gave

lower

a b s o r p t i o n s .


19/31


20/31

It

will be

noted

th a t

when

using

the

f r i t t e d

source

of

d i s s o l v e d

diopside

in

accordance with

th i s

invent ion

as a body

a d d i t iv e in

the

amounts

set

forth in

tab le

II,

the

f i r i n g

tempera ture

was

e f f e c t i v e l y

reduced from

cone

9-10 to

cone

5-6. At the

same

t i m e ,

the

f i red

products

s t i l l

con ta ined ,

in addition

to

r e l a t i v e

ease

o f

process ing ,

t h o s e c r i t i c a l

c h a r a c t e r i s t i c s

so

e s s e n t i a l

to

commercial

success ,

namely,

f i r i n g

s h r in k a g e , a b s o rp t io n ,

warpage,

and

modulus

of

rup ture .

These

p ro p e r t i e s a re

all well within the values

required by

the

trade . I t

will also be observed that

o t h e r

additives , even

s y n th e t i c d io p s id e ,

when added

to

the


body provided a

number

of

se r ious

drawbacks. The

f lux ing

g l a s s e s

of this invention

have exce l len t

p r o p e r t i e s

in

a l l

c a t e g o r i e s

needed

for

fluxing

action and

are

not

o u t s t a n d in g

in

jus t

a

few of

such

c a t e g o r i e s .

Another

aspect

of

the

in v e n t io n

re s id e s

in

ba lanc ing

t h e

def locculen t ox ides

and

f lo c c u le n t a lk a l in e e a r th s th a t

a r e

gradua l ly

leached

from

the

f lux ing g lass

firt when

it

is added

t o

the

ceramic

s l ip .

Such

balancing imparts

or

improves slip

s t a b i l i t y ,

tha t

is,

i t

main ta ins

the

v i s c o s i t y

of the

s l ip

at workable

v i s c o s i t y v a l u e s .

More

p a r t i c u l a r l y , a s

the

a lk a l in e e a r th s

are

leached

from

the

f r i t ,

they

tend to

reaise the

v i s c o s i t y

and

even solidify

the

s l ip .

But

i f

the deflocculent oxides

are

leached

along

with the

f l o c c u l e n t s ,

t h e

def locculen t ox ides counte rba lance

or

c o u n te ra c t

t h e d e f l o c c u l e n t s

to

provide a

s ta b le ,

workable

s l i p v i s c o s i t y .

De f lo c c u le n t o x id e s

include

any

metal

oxide that

may

be

made

a

component

of

the

g l a s s

frit and

which

c o u n te ra c t s

as

described the

f l o c c u l a t i n g

action

o f

the

a lka l ine ea r ths .

Examples

of

these

are

the a lka l i

metal

o x id e s

such

as

sodium

oxide,

po tass ium

oxide,

and

l i th ium oxide . Afte r

leaching

from

the

g la s s ,

the def locculen t ox ides

are

u s u a l l y p r e s e n t

in

the

slip

as

s i l i c a te s s u c h

as

sodium

s i l i c a t e ,

p o ta s s iu m


21/31

s i l i c a t e ,

a n d l i t h i u m s i l i c a t e .

The

amount

of

d e f lo c c u le n t o x id e s

needed in the

glass

f r i t

d e p e n d s

on

how

much flocculent

a lk a l in e e a r th s

are

leachable

from

the

g l a s s .

Normally,

however,

at le as t 5%

by

weight

of the

glass

f r i t s h o u l d

be


oxides .

The amount

leached for both

t h e

d e f lo c c u le n t

oxides and the flocculent

a l k a l i n e

earths

may

be in

the

par ts

per

mi l l io n

range,

a l though

s u b s t a n t i a l l y l a r g e r

c o n c e n t ra t io n s

are

p o s s i b l e .

The absolute

amounts

leachable

f o r

e i th e r

the


oxides

or

f l o c c u l e n t a l k a l i n e e a r t h s

a r e

not so

c r i t i c a l

as

is the c i rcumstance tha t

the

two

a l k a l i n e

ma te r i a l s be p r e s e n t in amounts s u f f i c i e n t to counte rba lance o r

counte rac t

each other to

the

e x te n t

they a re respec t ive ly

l e a c h e d

from

the f r i t

upon

i ts

d i s p e r s a l

in

a

ceramic

s l ip .

T h e r e r e s u l t s

a

buffer

or

n e u t r a l i z a t i o n - l i k e e f f e c t

by

which the


oxides

s u c c e s s fu l ly p re v e n t

th e f lo c c u le n t a lk a l in e e a r th

from

so

changing

the

v i s c o s i t y

of the

s l ip

t h a t

it becomes

unworkable. The

net

r e s u l t

is

even

be t te r than

adding

sodium s i l ica te

or

t h e l i k e

to

the

s l ip

a f t e r

the frit has been added and

undergone some

leaching

away

of i t s s o l u b i l i t i e s . The

p re s e n t

fri t is able

t o

maintain

r e l a t i v e l y

cons tan t

r h e o l o g i c a l

p r o p e r t i e s

for

days

following

mi l l in g ,

re q u i r in g

the addi t ion

of

only

minimal

amounts

of

a

def locculen t such

as

s o d i u m s i l i c a t e .

Considering

the

prev ious

data

more fully

from the

s tandpoin t

o f

ba lanc ing

the


ox ides and f loccu len t

a lk a l in e

e a r t h s ,

Body

Compositions

11,

12

and

13

of Table II

use

v i t reous

d i o p s i d e

as

a

flux. The vi tr eou s

d iops ide

was

pre par ed by melting

t h e

oxides in correct p r o p o r t i o n s and r o l l - q u e n c h i n g to form c l e a r ,

u n c r y s t a l l i z e d

glass having

no

free (un rea cte d and

u n d i s s o l v e d )

a lk a l in e

e a r th s .

As

shown

by

Table

I I I ,

Body

Compositions

11,

12

and

13

within

one day were

too

viscous

to be removed

from

t h e

c o n ta in e r .

Refe rr ing

to

Table

IV,

i t wi l l

be noted that

t h e


22/31

modulus

of

rup ture

for

these

Body

Compositions

are

extremely

p o o r

compared,

for

example,

to

tha t

value for

Body

Composition

6 which

embodies the

presen t

in v e n t io n .

Test

bodies

were

made

from these

compositions immediately from the s l ip wh i le in i t i a l v i s c o s i t y

was

s t i l l

workable .

Body

Compositions

7 and

8

which

comprise

synthe t ic d iops ide

a l s o

contained

as

a

re s u l t u n re a c te d

a lk a l in e e a r th s .

Body

Compos i t ions

7

and

8

required more

sodium s i l ica te

because

of the

free

a l k a l i n e

ear ths

p re s e n t ,

but

once

the effe ct of the alk ali ne

earths

was

c o u n te ra c te d ,

the

s l ip

was quite

s tab le

as

no

a d d i t i o n a l

l e a c h i n g

would

be

e x p e c te d .

In

c o n t ra s t ,

Body Composition

6

r e p r e s e n t i n g

the invention

r e q u i r e d

only

a

normal

amount

of

d e f lo c c u le n t fo r

in i t i a l ly ma k in g

t h e

cas t ing s l ip

and

a

s l i g h t

a d d i t io n

a f t e r

24

hours,

a f te r which

the

slip was

s t a b l e .

The

following

Table

V

provides

six

a d d i t i o n a l

examples

of the

presen t

glass composition

from

which fri t

can

be made

as

d e s c r i b e d .


23/31

Ex t ra c t io n

measurements

were

c a r r i e d

out

on

powders

of

Examples

A

and B

of

Table

V,

and,

for

comparison

purposes ,

on

the

s y n t h e t i c

d iops ide , g lass

Flux

B,

and vitreous

d iops ide

of

Table

II.

In

each

case,

one

gram

of

the flux

powder having

a p a r t i c l e

size to

p a s s

all

but

3%

on

325

Mesh,

U.S.

Standard

Sieve,

was

shaken with

100

m i l l i l i t e r s

of

d i s t i l l e d

water for

24

hours. The

s o lu t io n

was

t h e n

f i l t e r e d

and diluted to

250

ml. The

elements

were

es t imated

on

t h e

d i lu te d

p o r t io n

by

atomic

a b s o r p t i o n .

Table VI shows the

r e s u l t s .


24/31

High

Ca++ extractions

lead

to

th ic k e n in g ,

while

high

Na

leads

t o

th inn ing

of the

slip. Example

A

has both

high

Ca++

and

r e a s o n a b l e

+

high Na , so th a t i ts behavior is tha t of a composite. It does

thicken

the

s l ip

somewhat

but nowhere

nearly as badly as

v i t r e o u s

d iops ide

does.

Example

B

contains

more

Na20

than

Example

A

t o

enhance

or

maintain Na

e x t r a c t a b i l i t y .

Tabel

VI

in d ic a te s

t h a t

the

Ca++

e x t r a c t i o n

from

Example

B

into solution has

indeed

been

d r a s t i c a l l y

reduced,

while

the

Na

has not

been

a f f e c t e d .

The

glass

compos i t ions

of Table V

are

d e t a i l e d

in

Table

VII

w i t h

re s p e c t

to

ex trac t ion and

s l ip

s t a b i l i t y .

All

c a s t in g

s l i p s

of

Table

VII

have

good v i s c o s i t y s t a b i l i t y .

The

same

technique

d e s c r ib e d

for

Table

VI

was

used in

de te rmin ing

t h e

e lementa l

c o n c e n t r a t i o n s

in

weight

per

cent. The

cas t ing

s l ip

u s e d

was

the

same

mix

as

in

Table

II, using

a

three

weight

per

cent

f l u x

glass ,

but

in addi t ion

1.5

grams

of soda

ash

were

added

p e r

kilogram

of

body.

All

cast bodies

using

these

flux

glasses

were

fired to

less

than

1%

p o ro s i ty

at

Seger

cone

5.

There

a r e

d i f f e r e n c e s in the phys ica l conditions of the bodies cast as t h e

glass

flux

is

changed.

For

ins tance ,

the

p r o p e r t i e s

may

change

in

hardness

to

s o f t n e s s ,

ease

of

trimming,

b r i t t l e n e s s

t o

p l a s t i c i t y ,

and

the

li ke. These fac to rs would be

f a c t o r s t o

cons ider

in

s e le c t in g a p a r t i c u la r g las s c o mp os i t io n

for

use

w i t h

any

p a r t i c u l a r

i n d u s t r i a l

body composition

mix. The

presen t

i n v e n t i o n

does,

t h e r e f o r e ,

p r o v i d e f l e x i b i l i t y

in

the

glass composition

t h a t

may

be used

without

losing

s l i p s t a b i l i t y

and

the usefu lness

of

t h e

com po si ti on as a body

f l u x .

While

the

p r e f e r r e d

embodiment hereof is

re p re s e n te d

by

a s l i p

cast


body,

as

will be understood

by


25/31


26/31

those skilled in the

a r t ,

the benef i ts

of the

presen t

i n v e n t i o n ,

though perhaps

not

as

pronounced

or

dramat ic

as they

appear

in

a

sanitary-ware body,

would

quite

l ik e ly

be

a p p l i c a b le

to

any

f i r e d ,

ceramic

body;

would

d e f i n i t e l y

be

a p p l i c a b l e

to

any

body

which

could

be

c h a r a c t e r i z e d

by

those

s k i l l e d

in this

p a r t i c l a r

a r t ,

a s

a

fe ld s p a th ic b o d y .

And,

while the

p r e f e r r e d

embodiment

hereof involves

s l ip

c a s t

s a n i t a ry -wa re ,

other

than

as

s l ip

s o l u b i l i t y

b e n e f i t s

are a

c o n s i d e r a t i o n ,

the

method

of

forming

the

body,

whether

by

e x t r u s i o n ,

dry pressing,

etc .

would have

no bearing

on

t h e f i n a l r e s u l t s

achieved, and as such, method of forming r e a l l y forms n o l imi t in g

fe a tu re

of

the

in v e n t io n d i s c lo s e d

h e r e i n .

The

examples

hereof

amply

demonstrate

that the

f i n e - g r a i n e d

d i o p s i d e

c r y s t a l s

of th is invent ion

lower the

f i r i n g

tempera ture

of the

feldspathic body

d i s c l o s e d

by

at

l e a s t th re e

Seger

cones .

Obviously

however, an

amount

of

the

c r y s t a l s

and/or

f r i t

o f t h i s

invent ion

which would

promote

any

measurable

reduction in

f i r i n g

temperature

and/or time of

a

ceramic

body

would consti tute

a

fluxing

amount .

Cer ta in ly , lowering

the

required

h e a t t r e a tme n t

even

one

Seger

cone

would involve

a fl uxi ng

amount

of the

d io p s id e c ry s ta l s

and/or

glass

of th i s in v e n t i o n .

Although

the

foregoing

d e s c r ib e s

severa l

embodiments of the

p r e s e n t

invent ion ,

i t

is

unders tood tha t the invent ion

may

be

p ra c t i s e d

i n

sti l l other forms

with in

the

scope

of the

fo l lowing

c la ims .


27/31

1.

A

s u b s t a n t i a l l y

c o mp le te ly v i t r e o u s ,

smelted,

c le a r

g l a s s

f r i t c o n t a i n i n g :

(a)

leachable

amounts of de fl oc cul ent oxides

and

f l o c c u l e n t

a lk a l in e

ear ths

and

adapted

to

serve as a

ceramic

body

body

flux

in

a

ceramic

s l ip

without

th ic k e n in g

the

s l i p

to

an

unworkable

v i s c o s i t y ,

(b)

s a id f r i t

be ing comple te ly l iqu id

at

a s me l t in g

tempera ture

of

about

26000F

and

c o n ta in in g

i n s o l u t i o n

the

diops ide

p re c u rs o rs

CaO,

MgO,

and

SiO2

in

ananount

of

at

leas t

35%

by weight

of the

f r i t ,

(c)

s a id f r i t

being

adapted

upon

hea t ing

to

c r y s t a l l i z e

from

solu t ion a t

l e a s t

a

f lux ing

amount of

said

p re c u rs o rs

i n

the form

of fine

d iops ide c rys ta ls hav ing

an

a v e ra g e

p a r t i c l e

s ize

less than

one

micron and

b e i n g s u b s t a n t i a l l y

free

of unreacted

a lk a l in e

e a r th s ,

and

(d)

s aid d e f lo c c u le n t o xide s and f lo c c u le n t a lk a l i n e e a r th s

being

leachable

from

said

f r i t i n

s u f f i c i e n t r e l a t i v e

amounts

to

counterbalance each

other and

prevent

s a i d

th ickening

of the s l ip to

an

unworkable v i s c o s i t y .

2.

The

glass

f r i t

of

claim

1

in which

at

l e a s t

50%

by weight

o f

said

d iops ide

p re c u rs o rs

are

converted

to

said

d i o p s i d e c r y s t a l s

during

said

h e a t i n g .


28/31

3.

The

glass

f r i t

of

claim

1

in which said

heating

is

at

a

tempera ture

from about

Seger

cone

five

(5) to

about

cone

six

(6 ) .

4. The

glass

fr i t o f

claim

1

in

which

said

composition

c o mp r i s e s

in

weight

percen t

a b o u t :

said

a d d i t i v e

being

selected from

one

or more

of the

f o l l o w i n g

in

approximeta ly

the

percen t

i n d i c a t e d

based

on

the

t o t a l

w e i g h t

of the

g l a s s :

sa id f luor ine

when

presen t

being

introduced into the

batch

as

a

f luor ide of

at

l e a s t

one

metal of the

c o mp o s i t io n .

5. The

glass

f r i t

of claim

1

in which said

composition

c o mp r i s e s

in

weight

percen t

a b o u t :

said

a d d i t iv e

being

selected from

one or

more

of the

f o l l o w i n g


29/31

in approximately

the

percen t

i n d i c a t e d

based

on

the to ta l

we ig h t

of

the

g l a s s :

6.

The

glass

f r i t

of

claim

1

in which

s a i d f r i t

i s a t t a in e d

by

smel t ing

dolomite

and

l i t h o s p a r

in

a weight

r a t i o n

of about

76:24 to

11:89,

r e s p e c t i v e l y ,

and then

f r i t t i n g

the

s m e l t .

7.

A

f i r e d

sani tar y-wa re body con tai nin g a fluxi ng

amount of

p r e c i p i t a t e d

c ry s ta l s

of

d iops ide chemica l ly

formed insitu

d u r i n g

said

f i r i n g

from the

d iops ide

p r e c u r s o r s

CaO,

MgO

and

Si02,

s a i d

p r e c u r s o r s

i n i t i a l l y

in t roduced in to

said

body prior

to

f i r i n g

i n

the

form

of

a

c lea r ,

f r i t t e d

comple te ly

v i t r i f i e d s o l u t i o n

t h e r e o f ,

with

a


por t ion

of said

c r y s t a l s

having

an

a v e ra g e

p a r t i c l e s

size

less than

one

micron,

said

f r i t

b e i n g s u b s t a n t i a l l y

free

of both

c ry s ta l l in e p h a s e s

and u n re a cte d a l k a l in e e a r t h s

and c o n ta in in g def locculen t ox ides in a q u a n t i ty s u f f i c i e n t t o

c o u n te rb a la n c e

the

effect of

f l o c c u l e n t a l k a l i n e e a r t h s

p r e s e n t

to

the extent

they are

r e s p e c t i v e l y

leached

upon

d i s p e r s a l

o f

said

f r i t

in

a

ceramic

s l i p .

8.

The

f i re d

sanitary-ware body

of

claim

7

in

which sa id


diopside

crys ta ls comprise

from

about 0.1%

to

a b o u t

5.0%

by

weight

of

said

body.

9.

The fired

sanitary-ware body

of cla im 7

in

which

s a i d


diopside

c r y s t a l s

are

formed

from

the

c o m p l e t e l y

v i t r i f i e d

f r i t

of claim

7,

said

f r i t

having

the

f o l l o w i n g

composition prior

to said

f i r i n g :


30/31

sa id addi t ive

being

selected from

one

or

more

of the

f o l l o w i n g

in

approximate ly

the

percen t

ind ica ted based

on

the

t o t a l

w e i g h t

of

the

g l a s s :

said

f l u o r i n e

when

presen t

being

in troduced in to

the

batch

as a

f l u o r i d e

of

at

leas t

one

metal of the

c o mp o s i t io n .

10.

The

f i re d

sanitary-ware body

of

claim

7

in

which

s a i d


d io p s id e c ry s ta l s

are

formed from the

c o mp le te ly

v i t r i f i e d

frit of claim

8,

s a id f r i t

having

the

f o l l o w i n g

compos i t ion pr ior

to said

f i r i n g :

said

a d d i t iv e

being

s e le c te d

from

one

or more

of

the

f o l l o w i n g

in

approximate ly

the

percen t

ind ica ted based

on

the

t o t a l

we ig h t

of

the

g l a s s :


31/31

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Casting Slip production of Sanitaryware

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