CA1109896A - Foundry binder - Google Patents
Foundry binderInfo
- Publication number
- CA1109896A CA1109896A CA302,458A CA302458A CA1109896A CA 1109896 A CA1109896 A CA 1109896A CA 302458 A CA302458 A CA 302458A CA 1109896 A CA1109896 A CA 1109896A
- Authority
- CA
- Canada
- Prior art keywords
- silicate
- potassium
- core
- binder
- sodium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000011230 binding agent Substances 0.000 title claims abstract description 16
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 28
- 235000019353 potassium silicate Nutrition 0.000 claims abstract description 26
- 238000000034 method Methods 0.000 claims abstract description 14
- 239000004111 Potassium silicate Substances 0.000 claims abstract description 13
- 229910052913 potassium silicate Inorganic materials 0.000 claims abstract description 13
- NNHHDJVEYQHLHG-UHFFFAOYSA-N potassium silicate Chemical compound [K+].[K+].[O-][Si]([O-])=O NNHHDJVEYQHLHG-UHFFFAOYSA-N 0.000 claims abstract description 13
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 11
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 11
- 229910052681 coesite Inorganic materials 0.000 claims abstract description 10
- 229910052906 cristobalite Inorganic materials 0.000 claims abstract description 10
- 229910052682 stishovite Inorganic materials 0.000 claims abstract description 10
- 229910052905 tridymite Inorganic materials 0.000 claims abstract description 10
- 239000004115 Sodium Silicate Substances 0.000 claims description 25
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 15
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 15
- 239000004576 sand Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims description 3
- 238000000465 moulding Methods 0.000 claims description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 15
- 229910002092 carbon dioxide Inorganic materials 0.000 description 11
- 230000015556 catabolic process Effects 0.000 description 10
- 235000019351 sodium silicates Nutrition 0.000 description 10
- 239000007787 solid Substances 0.000 description 9
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 7
- 239000001569 carbon dioxide Substances 0.000 description 6
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910052700 potassium Inorganic materials 0.000 description 4
- 239000011591 potassium Substances 0.000 description 4
- 230000006835 compression Effects 0.000 description 3
- 238000007906 compression Methods 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 2
- 229930006000 Sucrose Natural products 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- CHWRSCGUEQEHOH-UHFFFAOYSA-N potassium oxide Chemical compound [O-2].[K+].[K+] CHWRSCGUEQEHOH-UHFFFAOYSA-N 0.000 description 2
- 239000005720 sucrose Substances 0.000 description 2
- 235000000346 sugar Nutrition 0.000 description 2
- 101100095557 Caenorhabditis elegans ulp-1 gene Proteins 0.000 description 1
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- 229920001353 Dextrin Polymers 0.000 description 1
- 239000004375 Dextrin Substances 0.000 description 1
- 229910001060 Gray iron Inorganic materials 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 235000019425 dextrin Nutrition 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000005058 metal casting Methods 0.000 description 1
- 229910001950 potassium oxide Inorganic materials 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
- B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
- B22C1/186—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents contaming ammonium or metal silicates, silica sols
- B22C1/188—Alkali metal silicates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B12/00—Cements not provided for in groups C04B7/00 - C04B11/00
- C04B12/04—Alkali metal or ammonium silicate cements ; Alkyl silicate cements; Silica sol cements; Soluble silicate cements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
- C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
- C04B35/6303—Inorganic additives
- C04B35/6316—Binders based on silicon compounds
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Mold Materials And Core Materials (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
- Detergent Compositions (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In the CO2-silicate foundry binder process the use of a proportion of potassium silicate, having a molar ratio SiO2:K2O in the range 1.6 to 2.2:1, significantly increases the setting rate of the binder.
In the CO2-silicate foundry binder process the use of a proportion of potassium silicate, having a molar ratio SiO2:K2O in the range 1.6 to 2.2:1, significantly increases the setting rate of the binder.
Description
l ~ g8 9 6 cG.13~1 This invention relates to core binders and par~icularly to an improved carbon dioxide sili,cate process ror making moulds and cores for the foundry industry.
For some years a process has be~n u~ed in industry in which a moulding sand is mixed with, as a binder, a sodium silicate solution to form a core or mould - hereinafter referred to as a core - which is treated with carbon dioxide ~as to set the core by reacting with the sodium silicate.
In production of these C02 silicate cores it is necessary to gas the core for a sufficient time to obtain adequate strength for handling purposes. Cores ~roduced by this process should have a reasonable shelf life and then it is desirable that the core, after it has been used in a metal castin~ operation, should be readily disintegrated and removed from the metal casting.
The disintegration or breakdown of the core can be assisted by the inclusion of starch, sugar or dextrin and like materials with the sodium silicate solution. It is common practice in commercial sodium silicates desi~ned for foundry industry to include a breakdown agent.
In British Specification No. 874,117 a process for binding particulate refractory material has been disclosed in which the binder is a solution of potassium and sodium silicates in which the weight ratio ~iO2:(K20+Na20) is at least 3:1 and the ' weight ratio K20:Na20 is from 2:1 to 4:1. The mixture of silicates and binder can be hardened using carbon dioxide gas.
The lowest molar ratio SiO2:K20 disclosed in this specification is 3.3:l and this is a commonly available form of potassium silicate.
For some years a process has be~n u~ed in industry in which a moulding sand is mixed with, as a binder, a sodium silicate solution to form a core or mould - hereinafter referred to as a core - which is treated with carbon dioxide ~as to set the core by reacting with the sodium silicate.
In production of these C02 silicate cores it is necessary to gas the core for a sufficient time to obtain adequate strength for handling purposes. Cores ~roduced by this process should have a reasonable shelf life and then it is desirable that the core, after it has been used in a metal castin~ operation, should be readily disintegrated and removed from the metal casting.
The disintegration or breakdown of the core can be assisted by the inclusion of starch, sugar or dextrin and like materials with the sodium silicate solution. It is common practice in commercial sodium silicates desi~ned for foundry industry to include a breakdown agent.
In British Specification No. 874,117 a process for binding particulate refractory material has been disclosed in which the binder is a solution of potassium and sodium silicates in which the weight ratio ~iO2:(K20+Na20) is at least 3:1 and the ' weight ratio K20:Na20 is from 2:1 to 4:1. The mixture of silicates and binder can be hardened using carbon dioxide gas.
The lowest molar ratio SiO2:K20 disclosed in this specification is 3.3:l and this is a commonly available form of potassium silicate.
- 2 - /... ~P
~ .
.
11~)9896 lt has now been found that if particularly fast gassing times are desired and if improved core breakdown is required, such benefits can be achieved by using particular potassium silicates in the binder, having selected ratios of potassium oxide and silicon dioxide.
Accordingly, the present invention provides a process for the production of foundry cores using the CO2-silicate process, in which a moulding sand is mixed with, as a binder, sodium silicate solution and the core or mould is gassed with CO2, the use of an amount of potassium silicate to replace at least part of the sodium silicate, said potassium silicate having a molar ratio Sio2:K2O in the range 1.6 to 2.2:1, sufficient to reduce the gassing time for setting the core.
The preferred molar ratio of SiO2:K2o is in the range 1.8 to 2.2:1. Potassium silicates at molar ratios above 2.3 and at solids of 50~ by weight are too viscous to handle satisfactorily in the foundry environment.
It has also been found that even when significant proportions of sodium silicates are present in the silicate binder a surprising decrease in gassing times can still be obtained. The preferred sodium silicates have a molar ratio sio :Na G in the range 1.65 to 2.8:1, more preferably 2 to 2.4.
The proportion of sodium silicate in the silicate binder should not exceed 75~ by weight if significant improvements are to be achieved.
From the viewpoint of production of CO2 silicate cores, any reduction in gassing time gives a two-fold benefit. First of all it means that from any equipment a significantly greater output can be obtained and, secondly, it means a significant reduction in the ~109896 amount of carbon dioxide gas required to produce a specified number of cores.
- 3a -~1~98~6 c(l. 134 It ha~ also been found -that the efYect Or breakdown agents, 811Ch as sucrose, is enhanced when the silicate component comprises or COllSiStS of potassium silicates as earlier specified.
In addition, when reusiny reclaimed foundry sands, the use of potassium silicates has a further benefit in that the potassium silicates have a less harmful e~fect on the refractory nature of the reclaimed sand than do the normally used sodium silicates. Furthermore, in the range o~ potassium silicates used in this invention it has been found that the potassium silicates have a lower viscosity than the normally used sodium silicates, thus assistin~ in the ease of mixin~ o~ the silicate and sand.
In characterising cores prepared using the C02 silicate process it is normal to determine the compressive strength of the core immediately after the C02 gassing stage followed by compression strength after 24 hours and 48 hours in controlled conditions. A further test is carried out on the cores after casting to determine breakdown characteristics o~ the heat-treated core.
The breakdown test involves applying an impact load through a spring loaded plunger to the core to determine the number o~ impacts necessary to penetrate one centimetre into the core. The impact load is applied to a probe having a 3~
conical head giving a load of up to 31 kilograms. This test and tbe other tests used in this specification are described ill de-tail in the book "The C02-Silicate Process in Foundries", wri-tten by - 4 - t 11~989~ cG.13~
K.E.L. NichoLas and published by the British Cast Iron ~esearch Associa-tion, Alvechurch, Birmin~ham, in 1972.
Comparative tests were made using a s-tan~ard sodium silicate binder having 2.0 to 1 ratio at 45% solids, together with various potassium silicates. The cores were prepared usin~ 3.5% by wei~ht of the alkaline silicate solution mixed with a suitable Chelford sand. Cylindrical specimens were prepared of 2 inches diameter and 2 inches height and these were rammed in the usual fashion and gassed with carbon dioxide at flow rates 2.5, 10 and 20 litres per minute at 68.95 kilo-~ewtons per square metre pressure. The compression strengths of the samples were determined immediately as gassed and after periods of 24 and 48 hours. The specimens were stored at temperatures in the range 20 to 27C and relative humidities o~ the order o~
50%. The core breakdown properties were determined after incorporation in a grey iron casting weighing 25 kilograms poured at 1400C.
The results o~ these experiments are set out in Table I
below.
The binders used are indicated in Table I by letters A to E and compositions were as set out below:
Binder A is a sodium silicate having a 2.0 to 1 ratio at 45% solids.
Binder B is a potassium silicate having a 2.0 to 1 ratio at 45% solids.
Binder C is a potassium silicate havin~ a 1.8 to 1 ratio at 45% solids.
_ 5 -- / ~ -: ~ :
.
.
.
9896 ( ~ 3~-l 3i~ld~ ) is a ll-)tassiulll Si l:iC<I'~e l1CJV~ 1.6 to 1 ratio CI -t ~ 5 ','0 ~S O ~ ] ~; .
13i ~ c~ is a llol.ass:ium si l i( al;e 1iavin~r a 2.2 lo I ratio a t. ~ b so 1 i ~Is .
'I'~ lo~er ir~act breahdo~ f:i~ res in brackets inclicate i,he c:tf~cf. o:f the adcliiioll O:r 20/c by ~c.i~llt o:l 13-i.nder of sucrose.
_ (; ~ /- -1~9896 cG.134 ~ 1--n O n _ ~_ I~7 ~ o ~n ~
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, to t~ tr ~ t t~ ~ t r t~, J ~ tn ~ t ~ ~
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t~ r r ~ t~, r ~ ~o ` ~ ~
'` O t~ O_ t" ~ _ ~ ~D
r r C~ x ,_ ~ ~ t~ ~ _~ P~ tl ta C~ t~ ~n ~n _ O ~ ~ E~
P~ _ t~ t. ~ _ _ ~ 1- ~
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IJoo C~ ~ ~ ~
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t~ 1' . _ _ __ _ ~
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O O ~ O O O ~n O ~ ' _ _ .__ C~ ~ ~
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1~ C~ ~ I_ 1~
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~o p ei ~1 E~l .~ r ~ _ r ~ o o .. 1~ ~ ~q .~ w . .
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c~ 3/1 1t will be seen from Table 1 that the iml11ediate "As Gassed" con1pression strength of the samp'Les is achieved at a signif'icantly shor-ter -time using potassium silicate -than -the com1l1ercially used sodium silicate. This means that greater S production rates can be achieved from a plant and significarl-tly less carbon dioxide is required ~or any set number of cores.
The 24 and ~8 hours strengths, using po-tassium silica-te, did not reac1~ the of'ten unnecessarily high compression stren~ths frequently ~net with using known sodium silica-tes. This fac-tor probably contributed to the better breakdown achieved using potassium silicates.
~he i11lpact strength indicates -tha-t the breakdown of the cores bound with potassium silicate is slightly bet-ter than that of standard sodium silicate. When breakdown aids such as sugar are incorporated into potassium silicate binders, -there is even more signi~icant improvement of properties.
It will be appreciated that, while the potassium silicates specified in this specification give a significant improvement in gassing time, they are more expensive than the corresponding sodium silicates. A commercial balance can frequently be struck between the outstandingly short gassing times obtained using only potassium sil:icates at a higher C09t and the significant improvements which can be achieved by using a blend Or -the potassium and sodium silicates.
Tables II and lII give further detai'ls of' further -test samples using mixtures of potassium and sodium silicates.
Gassing times ~ere selected to acbieve compara'ble compressive , , I
~-- .
' 11q.~9~3~ ( (i .I:3~1 ~I,r(?r~ iu l,llo ox~ rllllerll,al (oreH. 'I'h(` coros w~r(~ Ytor~.?~i l. '()~ yO r~lat,iv~ h~.lml(lity.
Or.~ t`(l 1 ~1 'I`a~ ni1 lll w(~r~:
llin(lot l~`- pota~lulll ~:i..ll.ca~e ,53'~0 ~oli(ls (Si()2:K~0 .
.():I molllr) llrl~l 25~o hy w~i~tlt ~od:i.um ~ icate ~6~/o ~oli.ds (';iO2:
Illr~ r l; I)o~ ium ~i licate 53% sol:i.d~ (Si.02:K20 -2.():l molur) ~.~n(l 5()% by wei.~hl ~ouium ~L:I.:i.cate ~6% sol-l.ds (SiO2:
Na2() ~ 2.(:):l nlo~lr).
I() 111ll~ler 1l - 1)tu9~i.um gil.iC~3t~ 5'3'~0 ~olids (SiO2:K20 _ 2.():l mol~lr) l:lrl~ 750/o hy wei~ht ~od:i.ulll ~ i.cute ~t;t~o sol:i.d~ ~Sl()2:
Nu20 _ ~I.O:I.lmol.a:r).
l~ln(lor J ~ :1.00/a by wci~ht sod:i.um ~ilicate 4tj% so.Li(l~
(Si 0~: Na~O - 2 . O: 1. mo:l.ar).
IS BLtld~r K _ p(Jlasslum ~:IJ.icate 53'~o sol.irlH (S:iO2:K20 -2.":l.lllolnr) ~3nd 25% by wei~ht ~odlum sili.cflt~ ~t3% solids (SiO2:
Na~0 - 2.():1 mol.ar)-l~i.n(l~:r 1~ - pota~l.um silicate 53% solids (SiO2:K20 -~.2::l. mollr) ~-3nd 5()% by w~i~ht sodium ~illcate 46% solid~ (Si.02:
N~3~0 - 2.0~ llolar).
I3in(l~r M - pota~sl.um ~illcate 53% solid~ (Si.02:K20 -2.2.:l.lllol.ar) all(l 75~ by w~L~ht sodium silicate ~6% sol.ids (SiO2:
N~0 _ 2.0:l mo:Lflr).
ln ~098~
cG. 134 . ~ T
~ .
.
11~)9896 lt has now been found that if particularly fast gassing times are desired and if improved core breakdown is required, such benefits can be achieved by using particular potassium silicates in the binder, having selected ratios of potassium oxide and silicon dioxide.
Accordingly, the present invention provides a process for the production of foundry cores using the CO2-silicate process, in which a moulding sand is mixed with, as a binder, sodium silicate solution and the core or mould is gassed with CO2, the use of an amount of potassium silicate to replace at least part of the sodium silicate, said potassium silicate having a molar ratio Sio2:K2O in the range 1.6 to 2.2:1, sufficient to reduce the gassing time for setting the core.
The preferred molar ratio of SiO2:K2o is in the range 1.8 to 2.2:1. Potassium silicates at molar ratios above 2.3 and at solids of 50~ by weight are too viscous to handle satisfactorily in the foundry environment.
It has also been found that even when significant proportions of sodium silicates are present in the silicate binder a surprising decrease in gassing times can still be obtained. The preferred sodium silicates have a molar ratio sio :Na G in the range 1.65 to 2.8:1, more preferably 2 to 2.4.
The proportion of sodium silicate in the silicate binder should not exceed 75~ by weight if significant improvements are to be achieved.
From the viewpoint of production of CO2 silicate cores, any reduction in gassing time gives a two-fold benefit. First of all it means that from any equipment a significantly greater output can be obtained and, secondly, it means a significant reduction in the ~109896 amount of carbon dioxide gas required to produce a specified number of cores.
- 3a -~1~98~6 c(l. 134 It ha~ also been found -that the efYect Or breakdown agents, 811Ch as sucrose, is enhanced when the silicate component comprises or COllSiStS of potassium silicates as earlier specified.
In addition, when reusiny reclaimed foundry sands, the use of potassium silicates has a further benefit in that the potassium silicates have a less harmful e~fect on the refractory nature of the reclaimed sand than do the normally used sodium silicates. Furthermore, in the range o~ potassium silicates used in this invention it has been found that the potassium silicates have a lower viscosity than the normally used sodium silicates, thus assistin~ in the ease of mixin~ o~ the silicate and sand.
In characterising cores prepared using the C02 silicate process it is normal to determine the compressive strength of the core immediately after the C02 gassing stage followed by compression strength after 24 hours and 48 hours in controlled conditions. A further test is carried out on the cores after casting to determine breakdown characteristics o~ the heat-treated core.
The breakdown test involves applying an impact load through a spring loaded plunger to the core to determine the number o~ impacts necessary to penetrate one centimetre into the core. The impact load is applied to a probe having a 3~
conical head giving a load of up to 31 kilograms. This test and tbe other tests used in this specification are described ill de-tail in the book "The C02-Silicate Process in Foundries", wri-tten by - 4 - t 11~989~ cG.13~
K.E.L. NichoLas and published by the British Cast Iron ~esearch Associa-tion, Alvechurch, Birmin~ham, in 1972.
Comparative tests were made using a s-tan~ard sodium silicate binder having 2.0 to 1 ratio at 45% solids, together with various potassium silicates. The cores were prepared usin~ 3.5% by wei~ht of the alkaline silicate solution mixed with a suitable Chelford sand. Cylindrical specimens were prepared of 2 inches diameter and 2 inches height and these were rammed in the usual fashion and gassed with carbon dioxide at flow rates 2.5, 10 and 20 litres per minute at 68.95 kilo-~ewtons per square metre pressure. The compression strengths of the samples were determined immediately as gassed and after periods of 24 and 48 hours. The specimens were stored at temperatures in the range 20 to 27C and relative humidities o~ the order o~
50%. The core breakdown properties were determined after incorporation in a grey iron casting weighing 25 kilograms poured at 1400C.
The results o~ these experiments are set out in Table I
below.
The binders used are indicated in Table I by letters A to E and compositions were as set out below:
Binder A is a sodium silicate having a 2.0 to 1 ratio at 45% solids.
Binder B is a potassium silicate having a 2.0 to 1 ratio at 45% solids.
Binder C is a potassium silicate havin~ a 1.8 to 1 ratio at 45% solids.
_ 5 -- / ~ -: ~ :
.
.
.
9896 ( ~ 3~-l 3i~ld~ ) is a ll-)tassiulll Si l:iC<I'~e l1CJV~ 1.6 to 1 ratio CI -t ~ 5 ','0 ~S O ~ ] ~; .
13i ~ c~ is a llol.ass:ium si l i( al;e 1iavin~r a 2.2 lo I ratio a t. ~ b so 1 i ~Is .
'I'~ lo~er ir~act breahdo~ f:i~ res in brackets inclicate i,he c:tf~cf. o:f the adcliiioll O:r 20/c by ~c.i~llt o:l 13-i.nder of sucrose.
_ (; ~ /- -1~9896 cG.134 ~ 1--n O n _ ~_ I~7 ~ o ~n ~
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o~ ~ ~o r t~
~ ~3 ~O _ ~1 ~ ~n_ _ ~d H
, to t~ tr ~ t t~ ~ t r t~, J ~ tn ~ t ~ ~
--' ~ r ~ _ (D
t~ r r ~ t~, r ~ ~o ` ~ ~
'` O t~ O_ t" ~ _ ~ ~D
r r C~ x ,_ ~ ~ t~ ~ _~ P~ tl ta C~ t~ ~n ~n _ O ~ ~ E~
P~ _ t~ t. ~ _ _ ~ 1- ~
_ . _ _,_ ~t--,,~
IJoo C~ ~ ~ ~
. t~ ~
t~ 1' . _ _ __ _ ~
.__ . ~ _ ., ' 11~39896 ~ cG. 134 o ~
.
~ ~
_ r ~ ~ 1- ~
O O ~ O O O ~n O ~ ' _ _ .__ C~ ~ ~
~ o ~ t~ ~ ~
_ _ _ o o ~ ~o ~ ~
~ ~ ~ ~
~ I~ ~Or ~ ~!
1~ C~ ~ I_ 1~
~ ~ r ~ I ~ ~ H
~o p ei ~1 E~l .~ r ~ _ r ~ o o .. 1~ ~ ~q .~ w . .
;~ ~^
_ _ o ~,~
_ _ ~
, c~ ~
_ '~ , X' . . ~
~ .
8~S
c~ 3/1 1t will be seen from Table 1 that the iml11ediate "As Gassed" con1pression strength of the samp'Les is achieved at a signif'icantly shor-ter -time using potassium silicate -than -the com1l1ercially used sodium silicate. This means that greater S production rates can be achieved from a plant and significarl-tly less carbon dioxide is required ~or any set number of cores.
The 24 and ~8 hours strengths, using po-tassium silica-te, did not reac1~ the of'ten unnecessarily high compression stren~ths frequently ~net with using known sodium silica-tes. This fac-tor probably contributed to the better breakdown achieved using potassium silicates.
~he i11lpact strength indicates -tha-t the breakdown of the cores bound with potassium silicate is slightly bet-ter than that of standard sodium silicate. When breakdown aids such as sugar are incorporated into potassium silicate binders, -there is even more signi~icant improvement of properties.
It will be appreciated that, while the potassium silicates specified in this specification give a significant improvement in gassing time, they are more expensive than the corresponding sodium silicates. A commercial balance can frequently be struck between the outstandingly short gassing times obtained using only potassium sil:icates at a higher C09t and the significant improvements which can be achieved by using a blend Or -the potassium and sodium silicates.
Tables II and lII give further detai'ls of' further -test samples using mixtures of potassium and sodium silicates.
Gassing times ~ere selected to acbieve compara'ble compressive , , I
~-- .
' 11q.~9~3~ ( (i .I:3~1 ~I,r(?r~ iu l,llo ox~ rllllerll,al (oreH. 'I'h(` coros w~r(~ Ytor~.?~i l. '()~ yO r~lat,iv~ h~.lml(lity.
Or.~ t`(l 1 ~1 'I`a~ ni1 lll w(~r~:
llin(lot l~`- pota~lulll ~:i..ll.ca~e ,53'~0 ~oli(ls (Si()2:K~0 .
.():I molllr) llrl~l 25~o hy w~i~tlt ~od:i.um ~ icate ~6~/o ~oli.ds (';iO2:
Illr~ r l; I)o~ ium ~i licate 53% sol:i.d~ (Si.02:K20 -2.():l molur) ~.~n(l 5()% by wei.~hl ~ouium ~L:I.:i.cate ~6% sol-l.ds (SiO2:
Na2() ~ 2.(:):l nlo~lr).
I() 111ll~ler 1l - 1)tu9~i.um gil.iC~3t~ 5'3'~0 ~olids (SiO2:K20 _ 2.():l mol~lr) l:lrl~ 750/o hy wei~ht ~od:i.ulll ~ i.cute ~t;t~o sol:i.d~ ~Sl()2:
Nu20 _ ~I.O:I.lmol.a:r).
l~ln(lor J ~ :1.00/a by wci~ht sod:i.um ~ilicate 4tj% so.Li(l~
(Si 0~: Na~O - 2 . O: 1. mo:l.ar).
IS BLtld~r K _ p(Jlasslum ~:IJ.icate 53'~o sol.irlH (S:iO2:K20 -2.":l.lllolnr) ~3nd 25% by wei~ht ~odlum sili.cflt~ ~t3% solids (SiO2:
Na~0 - 2.():1 mol.ar)-l~i.n(l~:r 1~ - pota~l.um silicate 53% solids (SiO2:K20 -~.2::l. mollr) ~-3nd 5()% by w~i~ht sodium ~illcate 46% solid~ (Si.02:
N~3~0 - 2.0~ llolar).
I3in(l~r M - pota~sl.um ~illcate 53% solid~ (Si.02:K20 -2.2.:l.lllol.ar) all(l 75~ by w~L~ht sodium silicate ~6% sol.ids (SiO2:
N~0 _ 2.0:l mo:Lflr).
ln ~098~
cG. 134 . ~ T
3~ ~tv . ~g ~
~ ~ .
(~ ~3 ~D
o ,, ~Q ~
_ _ c~ ~ ~ ~ U~
o o C~ o o ~ ~ o ~ ~q g ~.
_ _ __ _ ~q O
~ O ~ !Z ~ ~ cn C~ 3 ~ ca ~-ao ~ ocO ~50 ~ _ ~ c~ ~ ~D ~.
Cll O C~ cn O CD cn o t~ u~ B, ,~.
~ _ ~) 1 o~
iP1~ ~ 1\~ H ~ ~ O H
1~ ~ o ct~ w a~ a~ ~ H
0 C~l ~ ~ 1~ 1- CD CJ~ 3 ~ GO
l ~.
o~ ~D~3= _ ~ O O ~ O O ~ O O
_ ._ U:~ g CJ~
C~ ~ cn ~ O ^~~D tD I:q ^J~ ~ p~
_ ~ _ Oo~ 0~ OC~ 03'=, ~1 _ ~n9 0~
c~ w ~ I~ !Z ~ ~
tD ^a cn ~ ~ ~ O 0~ tD a~ 4 C~ ) iP ~ P co ~ ~0' _ _ 96 cC;.134 O cn _ _ __ _ ~ 3 ~ Q
_ 5 5 ~" 3'~g~
_ ~ , cn cn u~ :d ~a~ ulP
1~ ~ ~t c~ cn o ~ c~ ~ ~D
~ C~ ~
^~ ~q~ U) E;~
-~5'o- ~
w, 3 2 _ H
C~ ~ H C~ 1~ H ~, W H
~ cn ~ ~ CJI ~ ~ C~l O~ V~
_. _ (Iq ' o ~' Cl~ ~ C0 C
1- 0 OD 1- tD O O Cl~ ~ t~
CD eD 0 1~ 0 ~ ~ ~ W
N Cl~ H O O 1-- --I C0 1~ ~rrq cq ~50-_ . ~ ~ _ ~ ~ c~ ~D ~,. W
n O ~ cn O ~ U~ O ~ , _ _ ~V~3 ~D
C~ e ;~, c,~ o ^a c~ ~D ~D
cn C~ ~ cn ~ 1-- ~ ~ ~ r~ P ~q cn ~ cn o o r o ~ D' e~ -
~ ~ .
(~ ~3 ~D
o ,, ~Q ~
_ _ c~ ~ ~ ~ U~
o o C~ o o ~ ~ o ~ ~q g ~.
_ _ __ _ ~q O
~ O ~ !Z ~ ~ cn C~ 3 ~ ca ~-ao ~ ocO ~50 ~ _ ~ c~ ~ ~D ~.
Cll O C~ cn O CD cn o t~ u~ B, ,~.
~ _ ~) 1 o~
iP1~ ~ 1\~ H ~ ~ O H
1~ ~ o ct~ w a~ a~ ~ H
0 C~l ~ ~ 1~ 1- CD CJ~ 3 ~ GO
l ~.
o~ ~D~3= _ ~ O O ~ O O ~ O O
_ ._ U:~ g CJ~
C~ ~ cn ~ O ^~~D tD I:q ^J~ ~ p~
_ ~ _ Oo~ 0~ OC~ 03'=, ~1 _ ~n9 0~
c~ w ~ I~ !Z ~ ~
tD ^a cn ~ ~ ~ O 0~ tD a~ 4 C~ ) iP ~ P co ~ ~0' _ _ 96 cC;.134 O cn _ _ __ _ ~ 3 ~ Q
_ 5 5 ~" 3'~g~
_ ~ , cn cn u~ :d ~a~ ulP
1~ ~ ~t c~ cn o ~ c~ ~ ~D
~ C~ ~
^~ ~q~ U) E;~
-~5'o- ~
w, 3 2 _ H
C~ ~ H C~ 1~ H ~, W H
~ cn ~ ~ CJI ~ ~ C~l O~ V~
_. _ (Iq ' o ~' Cl~ ~ C0 C
1- 0 OD 1- tD O O Cl~ ~ t~
CD eD 0 1~ 0 ~ ~ ~ W
N Cl~ H O O 1-- --I C0 1~ ~rrq cq ~50-_ . ~ ~ _ ~ ~ c~ ~D ~,. W
n O ~ cn O ~ U~ O ~ , _ _ ~V~3 ~D
C~ e ;~, c,~ o ^a c~ ~D ~D
cn C~ ~ cn ~ 1-- ~ ~ ~ r~ P ~q cn ~ cn o o r o ~ D' e~ -
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for the production of foundry cores using the CO2-silicate process, in which a moulding sand is mixed with, as a binder, sodium silicate solution and the core or mould is gassed with CO2, the use of an amount of potassium silicate to replace at least part of the sodium silicate, said potassium silicate having a molar ratio SiO2:K2O in the range 1.6 to 2.2:1, sufficient to reduce the gassing time for setting the core.
2. A process as claimed in claim 1 in which the molar ratio of the potassium silicate is in the range 1.8 to 2.2:1.
3. A process as claimed in claim 1 in which the potassium silicate binder comprises up to 75% by weight of sodium silicate having a molar ratio SiO2:Na2O in the range 1.65 to 2.8:1.
4. A process as claimed in claim 3 in which the molar ratio of the sodium silicate is in the range 2 to 2.4:1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB18454/77 | 1977-05-03 | ||
| GB18454/77A GB1602122A (en) | 1977-05-03 | 1977-05-03 | Foundry binder |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1109896A true CA1109896A (en) | 1981-09-29 |
Family
ID=10112722
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA302,458A Expired CA1109896A (en) | 1977-05-03 | 1978-05-02 | Foundry binder |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS53144421A (en) |
| AU (1) | AU521140B2 (en) |
| BE (1) | BE866580A (en) |
| BR (1) | BR7802687A (en) |
| CA (1) | CA1109896A (en) |
| DE (1) | DE2819456A1 (en) |
| ES (1) | ES469437A1 (en) |
| FR (1) | FR2389432B1 (en) |
| GB (1) | GB1602122A (en) |
| IT (1) | IT1147755B (en) |
| NL (1) | NL7804734A (en) |
| SE (1) | SE438456B (en) |
| ZA (1) | ZA782513B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0148280B1 (en) * | 1982-12-16 | 1987-09-09 | Hüls Troisdorf Aktiengesellschaft | Water-containing hardenable shaped masses based on inorganic components, and method of producing shaped bodies |
| DE19951622A1 (en) | 1999-10-26 | 2001-05-23 | Vaw Ver Aluminium Werke Ag | Binder system based on water glass |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2829060A (en) * | 1954-10-25 | 1958-04-01 | Rolls Royce | Mould and method of making the same |
| GB874117A (en) * | 1959-06-19 | 1961-08-02 | Unilever Ltd | Processes for binding particulate solid materials and binders for use in such processes |
| US3442665A (en) * | 1966-06-13 | 1969-05-06 | Mueller Arno | Process for preparing sand cores using co2 cured silicate binders |
| JPS5224122A (en) * | 1975-08-20 | 1977-02-23 | Kato Asamichi | Method of making mold of good disintegrating property |
| JPS52124418A (en) * | 1976-04-14 | 1977-10-19 | Kato Tomomichi | Mold manufacturing |
-
1977
- 1977-05-03 GB GB18454/77A patent/GB1602122A/en not_active Expired
-
1978
- 1978-04-28 BR BR7802687A patent/BR7802687A/en unknown
- 1978-04-28 BE BE187288A patent/BE866580A/en not_active IP Right Cessation
- 1978-05-02 IT IT68005/78A patent/IT1147755B/en active
- 1978-05-02 ZA ZA00782513A patent/ZA782513B/en unknown
- 1978-05-02 JP JP5324978A patent/JPS53144421A/en active Pending
- 1978-05-02 CA CA302,458A patent/CA1109896A/en not_active Expired
- 1978-05-02 FR FR7812978A patent/FR2389432B1/fr not_active Expired
- 1978-05-02 AU AU35668/78A patent/AU521140B2/en not_active Expired
- 1978-05-03 ES ES469437A patent/ES469437A1/en not_active Expired
- 1978-05-03 DE DE19782819456 patent/DE2819456A1/en not_active Withdrawn
- 1978-05-03 NL NL7804734A patent/NL7804734A/en not_active Application Discontinuation
- 1978-05-03 SE SE7805139A patent/SE438456B/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| FR2389432A1 (en) | 1978-12-01 |
| FR2389432B1 (en) | 1982-11-05 |
| DE2819456A1 (en) | 1978-11-09 |
| BE866580A (en) | 1978-10-30 |
| IT1147755B (en) | 1986-11-26 |
| NL7804734A (en) | 1978-11-07 |
| ES469437A1 (en) | 1979-10-01 |
| ZA782513B (en) | 1979-12-27 |
| SE438456B (en) | 1985-04-22 |
| IT7868005A0 (en) | 1978-05-02 |
| BR7802687A (en) | 1978-12-19 |
| AU3566878A (en) | 1979-11-08 |
| SE7805139L (en) | 1978-11-04 |
| GB1602122A (en) | 1981-11-04 |
| JPS53144421A (en) | 1978-12-15 |
| AU521140B2 (en) | 1982-03-18 |
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