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CONTAINER GLASS FEEDERS :RECENT DEVELOPMENTS
IN THE CHOICE OF REFRACTORY MATERIALS
AFGM Edsa Shangri-la MANILA
SEPTEMBER 21, 2006
It is clearly understood that feeders play a crucial role
in the quality of glass produced by the furnace.
Any defects generated in the feeder zones could well
be found in the finished product, since the glass at this
stage works at relatively low temperatures and has a low capacity
to absorb any flaws.
In addition, market demands for quality are constantly on the
increase. Defects and flaws which were acceptable in the recent
past are now often cause for rejecting the glass. This jeopardizes
both yield and profitability of glass production.
Regardless of the design used to channel the glass from the
distributor to the machines,and to condition it thermally for forming,the choice of the refractories in glass contact is increasingly important.
SAINT-GOBAIN SEFPRO
GLASS CONTACT PRODUCT RANGE
Product Range AZS
Brand name ER 1681 RN ZA 33
Type of product Fused cast Bonded
Chemical analysis % Al2O3
ZrO2
50.9
32.5
75.5
10.5
Physical characteristics Bulk density
Open porosity %
Expansion at 1000 °C (%)
3.5
2
0.9
3.0
16
0.7
Glass quality Bubbling index 1100 °C-1h (0-10)
Stoning index 1250 °C- 36h (0-5)
AZS cat scratches
Corrosion resistance
(MGR – 72 h – 1350 °C)
1-2
0-1
+
100
1-2
1-2
+
80
Product range Alumina
Brand name JARGAL M SCIMOS M
BPAL ARKAL 60 PR
Type of product Fused cast Bonded Bonded
Chemical analysis % Al2O3
ZrO2
95.0
-
93.0
-
68.0
-
Physical characteristics
Bulk density
Open porosity %
Expansion at 1000 °C (%)
3.17
3
0.75
3.10
14
0.80
2.57
15
0.52
Glass quality Bubbling index 1100 °C-1h (0-10)
Stoning index 1250 °C-36h (0-5)
AZS cat scratches
Corrosion resistance
(MGR – 72 h – 1350 °C)
0-2
0
0
100
1-2
0-1
0
80
4-5
2-3
0
45
Out of these 5 types of products, which one is the best technico-
economical candidate to be used as feeder channel blocks for containers?
ER 1
681
Temperatures in ° Celsius
Corrosionin mm
JARGAL M
1200° 1600°1500°1400°1300°
12
9
6
3
1350°
Corrosion curves as a function of temperature ( PFT test )
BPAL ZA33
These curves show clearly that, for feeder
applications, where temperatures commonly occur
between 1200°C and 1280°C, corrosion resistance
difference between BPAL/ZA33 and fused cast AZS or
Alumina is very low.
For campaigns 8 – 12 years, which is the usual lifetime in containers, no need to use fused cast channel blocks.
What about « CAT SCRATCHES »?
One of the types of flaws most often
encountered in container glass are flaws
known as « cat scratches ».
Market sensitivity to this flaw is constantly
growing, and the flaw affects not only white
and flint glass, but also colored glass.
CAT SCRATCHES : definition
• Vitreous defect,
• Band of fine parallel cords,
• Located at the outside surface of the article,
• Diameter between 5 and 30 µm.
Microprobe analysis are done on the cat scratches section
CAT SCRATCHES: refractory characteristics
Melting / Refining
Throat
Working end
Feeder
Decrease of the glass potential to dissolve defects
Corrosion rate or temperature1550°C1350°C
1200°C
Main characteristic
Corrosion Defect formation potential
Based on several decades of experience in
expert appraisals of glass inclusions, the
research teams at Saint-Gobain SEFPRO
have developed highly precise typology of
these cat scratches.
In 85% of the cases, they are characterized
by the simultaneous presence of significant
amounts of zirconia and alumina.
Research into the ZrO2/Al2O3 ratio, and the
presence of certain elements which clearly show
a fusion origin (V2O5 for example in the case of
fuel-heated furnaces) have helped identify the
origin, which, in 80% to 90% of the cases, is the end
zone of the furnace : distributor and feeders.
This understanding has led many glassmakers to
reduce the use of Zircon-Mullite type materials as
much as possible, and generally speaking to
reduce the use of any material with significant
amounts of zirconia, in their feeders.
As a consequence of these results:
•A good way to significantly decrease AZS cat-scratches is to remove ZrO2 from « cold-end »:
- Working end = JARGAL M / SCIMOS M
- Feeders = BPAL
BPAL channel blocks feasability
TO-DATE :
inside width : 1500 mm60 ’’
bottom/walls thickness : 150 mm6 ’’
lenght : 610 mm18 ’’
inside height : 300 mm12 ’’
Bigger sizes on request.
BPAL references
ABOUT 500 FEEDER LINES SINCE 1990
WORLDWIDE
BPAL
BPAL
BPAL
Baby-food/flint glass/8.5 years campaign
BPAL
Baby-food/flint glass/8.5 years campaign
BPAL
LAST DEVELOPMENT (2005-2006)
ON BONDED ALUMINA FEEDER CHANNEL BLOCKS
HPAL
Even better corrosion resistance vs BPAL
+
Almost no blistering in contact
with extra-white soda-lime glass
New alumina product for feederSEFPRO SEFPRO SEFPRO
BPAL HPAL JARGAL MProduct Sintered Sintered FusedBulk density (gr/cm3) 3.1 3.2 3.17Open Porosity (%) 14 17 3Cold crushing strenght (Mpa) 190 160 200
Chemical analysis Al2O3 93 95 95 SiO2 6 2 0.5
Fe2O3 0.1 0.1 0.1
Corrosion resistance index @ 1300°C - 170h 100 115-120 125
Brand Name
ABOUT BLISTERING
Beside « cat scratches » , market can also be
sensitive to another type of flaw,
particulary for white glass: Blisters.
In the bonded Alumina range of products for
channel blocks one can find differences on
blistering, going more deeply in the
laboratory testing.
Blistering test “Le Pontet”
- 1100°C – 1h : immersed sample in the glass
- Scale : 0-1 (very low blistering) 10 (very high blistering)
-1100°C – 1h, white / flint soda lime glass (Fe2O3 = 1000 ppm) :
No big differentiation
0 2JARGAL M BPAL
HPAL
1
New crucible blistering test
- 1250°C – 30h or more : glass inside crucible, like in the feeder.
- Scale : 10 (low blistering) 100 (high blistering).
- Closer to feeder running conditions (T°, air, …)
- More blistering differences than in “LP” test.
- Need more tests in order to have a large data base
1250°C – 30h – white / flint soda lime glass :
More differentiation
JARGAL MBPAL
high Alumina product
10 20 30 40 50 60 70 80 90 100HPAL
New crucible blistering test
1250°C – 30h – extra-white soda lime glass (Fe2O3 < 300 ppm) :
10 20 30 40 50 60 70 80 90 100
New crucible blistering test
BPALhigh Alumina
product
HPAL
JARGAL M
1100 mm
New alumina product for feeder
HPAL
First two orders to be delivered end 2006
NEW PRODUCTS IN THE FIELD OF EXPENDABLES
Spouts with Zirchrom 85 inserts
ZA33 LB : Low seeding after starting up
ZA33HR : Higher thermal shock resistance
to prevent fracturation
SPOUT with ZIRCHROM 85 insert
ZA 33 (11 % ZrO2) or
ZIRAL 61 (19 % ZrO2)
Patented high chrome product (83,5 % Cr2O3) with better thermal shock resistance than any other
More than 3 times the life of monolithic spouts
Case story 1
- Cascade bowl ZA 33/ZIRCHROM 85 insert
- soda-lime glass CHR
- spout temperature : 1225° C
- average pull : 80/100 T pd
- average ring changes : every 8 weeks
- spout change : 8 hours, glass to glass
- Service life : 26 months (furnace repair)
- ZA33/F.C insert life (average) : about 12 months
Spouts with bonded chrome insert (ZIRCHROM 85)
Spouts with bonded chrome insert (ZIRCHROM 85)
Case story 2
Pre-heating procedure 6 h 6 h 6 h
Daily pull 50 tpd 40 tpd 15 tpd
Gob temperature 1170 °C 1180 °C 1280 °C
Glass flint flint flint
Average job changes/
Months 4 2 7
Service Life 20 to 26 months
ZA 33 mono service life 6 to 8 months
Expendables : ZA33LBReduction of Seeding after starting up and during production
Target : table-ware / flaconnage :
- short runs
- critical problem : mainly with plungers « seeding » during 1 to 10 h or more after starting, whatever the supplier
production losses : 8 to 12 K EUR/hour (EUROPE)
Blistering test for expendables
Test conditions : @ 1250°C, after 30h or with a record of the blistering during the test.
JARGAL M
Refractory sample
Glass
Blistering after 30 hTest conditions : Extra White soda lime glass, @ 1250°C – 30h
-333 : seeding during the starting hours (>30h within conditions of the present test)
-ZA33 LB : Lower blistering, decreasing with time
333 ZA33 LB
Product Blistering Index Observations333 8 Strong blistering on all the surfaces
ZA33 LB 1 to 4Low surface blistering on the bottom : Index 1
Which increase going on the top : Index 4
blisters
Index 1
Index 4
EXPENDABLES : new product ZA33
Tubes fracturation during production worldwide problem with any type of tube from any supplier :
- breakage during heating-up
- breakage after 1,2,3 … weeks of production
- breakage frequency unpredictable
difficulties to differentiate products (333, ZIRAL 61, competition) with standard thermal shock tests (USA thermal shocks test)
a specific test has been developed by R & D in order to differentiate products
A new thermal shock testing method
MethodologyOur methodology is based on the study of the impact of the thermal shock on the mechanical properties of the materials.
Samples of the material are first submitted to one or multiple severe thermal shock (rapid heat up to the test temperature followed by a thermal quenching in cold water) and then mechanically characterized (typically flexural strength MOR).
The residual MOR of the material is compared to the original strength of the material, and a characteristic ratio is calculated :
TR (%) = ( MOR before quenching – MOR after quenching ) x 100
MOR before quenching
The lower the ratio, the better the material withstands thermal shocks.
Among a family of materials having the same crystallographic properties, the best material thermal shock wise is the one with the lowest MOR loss ratio and higher residual strength after quenching.
*MOR=Modulus of rupture
Equipment Samples :
120 x 20 x 20 mm bars are sampled and dried in oven @ 110 °C
Procedure :
-Samples are machined, 2 sets of 5 from same bloc
- 5 samples are loaded in the furnace preheated at the test temperature, and soaked for 20 mn
- samples are removed from the furnace and immediately quenched in water
- once cool, samples are dried in an oven
- flexural modulus of rupture are measured at room temperature on both sets of samples
Electrical furnace
Cold Water box for quenching
A new Thermal shock testing method
New product ZA33
Graphe Delta MOR en fonction de la température de trempe
-70
-60
-50
-40
-30
-20
-10
0
10
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300
Température de trempe (°C)
Del
ta M
OR
( %
)
New product
AZS10
Whatever the quenching temperature is, the new product presents always lower MOR losses (and so a better thermal shock resistance).
*MOR=Modulus of Rupture
New product ZA33
Evolution de la perte MOR en fonction du nombre de cycles
-80
-70
-60
-50
-40
-30
-20
-10
0
0 1 2 3 4
Nbre de cycles
Per
te M
OR
(%
) New product
AZS10
This better thermal shock resistance remains available after 1, 2 or 3 shocks.
THERMAL SHOCK 1250 °C- 20°C
Standard
New
- Saint-Gobain SEFPRO is permanently looking for high
perfomance refractories in partnerships with
customers thank’s to it’s strong R&D, dedicated to
glass industry.
- Saint-Gobain SEFPRO has the largest Research
Center in the world specialising in refractories and
their interactions with different types of glass. 140
engineers and technicians in the R&D use the most
progressive, multidisciplinary technologies.
Saint-Gobain SEFPRO - R & D
Thank you