casting slip production of sanitaryware
TRANSCRIPT
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8/19/2019 Casting Slip production of Sanitaryware
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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.
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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 .
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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
v i t r i f i c a t i o n
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
v i t r i f i c a t i o n
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
v i t r i f i c a t i o n
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
v i t r i f i c a t i o n
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
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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 ,
c r y s t a l l i z a 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 ,
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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
s a n i t a r y - w a r e
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
c r y s t a l l i z a t i o n
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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
f e l d s p a t h i c
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
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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
f e l d s p a t h i c
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
f i r in g t e mp e ra tu re
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
f i r in g t e mp e ra tu re
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 ;
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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 :
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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
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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
s u b s t a n t i a l
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
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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
f e l d s p a t h i c
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
f e l d s p a t h i c
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.
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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.
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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 .
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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.
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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 :
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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
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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 .
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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
f e l d s p a t h i c
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
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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
d e f l o c c u l e n t
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
d e f l o c c u l e n t
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
d e f l o c c u l e n t
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
d e f l o c c u l e n t
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
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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 .
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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 .
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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
s a n i t a r y - w a r e
body,
as
will be understood
by
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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 .
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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 .
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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
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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
s u b s t a n t i a l
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
p r e c i p i t a t e d
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
p r e c i p i t a t e 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 :
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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
p r e c i p i t a t e 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 :
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