The measurement of high-temperature expansion as the standard of estimation the knock-out properties of moulding sands with hydrated sodium silicate

ARCHIVES OF METALLURGY AND MATERIALS Volume 59 2014 Issue 2 DOI: 10.2478/amm-2014-0123 K. MAJOR-GABRYŚ∗, S.M. DOBOSZ∗, P. JEL´ INEK∗∗ , J. JAKUBSKI∗, J. BE ˇ NO∗∗ THE MEASUREMENT OF HIGH-TEMPERATURE EXPANSION AS THE STANDARD OF ESTIMATION THE KNOCK-OUT PROPERTIES OF MOULDING SANDS WITH HYDRATED SODIUM SILICATE POMIAR EKSPANSJI WYSOKOTEMPERATUROWEJ JAKO KRYTERIUM OCENY WYBIJALNOŚCI MAS FORMIERSKICH Z UWODNIONYM KRZEMIANEM SODU The necessi y o ecei ing high quali y cas ings o ces unde aking esea ch o elabo a e moulding and co e sands ensu ing ob aining he ma e ials wi h ele an echnological pa ame e s and also wi h high en i onmen al s anda ds. The mos impo an g oup he e a e moulding sands wi h hyd a ed sodium silica e. Un o una ely, hei undamen al disad an ages a e weak knock-ou p ope ies. The a icle p esen s he mos commonly used me hods o measu ing he knock-ou p ope ies o moulding and co e sands. The au ho s p opose a new me hod o es ima ion his pa ame e . The me hod is based on he measu emen o high- empe a u e expansion. Keywo ds: moulding sand, hyd a ed sodium silica e, knock-ou p ope ies Po zeba uzyskiwania wysokiej jakości odlewów wymusza podejmowanie p ac badawczych dla o zymania mas o mie - skich i dzeniowych zapewniających uzyskanie wo zyw o odpowiednich pa ame ach echnologicznych, jednocześnie speł- niających wysokie wymogi och ony ś odowiska. Najważniejszą g upę s anowią u aj masy z uwodnionym k zemianem sodu. Nies e y jedną z ich pods awowych wad jes słaba wybijalność. W a ykule zos ały p zeds awione najczęściej s osowane me ody pomia u wybijalności mas o mie skich i dzeniowych. Au o zy zap oponowali nową me odę oceny wybijalności opie ającą się na pomia ze ekspansji wysoko empe a u owej. 1. In oduc ion The necessi y o ecei ing high quali y cas ings o ces unde aking esea ch o ob ain moulding and co e sands p o- iding o ob ain ma e ials wi h ele an echnological pa a- me e s and also wi h high en i onmen al s anda ds. Many na- ional and o eign scien i ic cen e s [1-12] unde ake scien i ic esea ch aiming o elabo a e new binding sys ems based on non oxic ino ganic binde s. The mos impo an g oup he e a e moulding sands wi h hyd a ed sodium silica e. Un o u- na ely hei main disad an age a e low knock-ou p ope ies and low abili y o mechanical eclama ion. Fo es ima ion o ac ions imp o ing moulding sands’ knock-ou p ope ies i ’s undamen al o use he app op ia e measu emen p ocedu e. In he a icle he e a e p esen ed he mos commonly used me hods o measu ing he knock-ou p ope ies o moulding and co e sands. The e is also p oposed a new me hod based on measu ing high- empe a u e expansion o es ed moulding sands. 2. Knock-ou p ope ies o moulding and co e sands The knock-ou p ope ies a e de ined as moulding o co e sand’s abili y o easy smashing ou (pou ing ou ) om mould (moulding sand) o om cas (co e sand) a e cooling he cas o knocking-ou empe a u e [13]. The knock-ou p ope - ies a e es ima ed by echnological me hods and acco ding o e ained s eng h R k cmeasu emen . 2.1. Technological me hods – he me hod ecommended by Polish S anda d no PN-85/H-11005 In echnological me hod ecommended by Polish S an- da d he e a e used s anda d cylind ical samples (ø50×50 mm) p epa ed om es ed moulding sand [13]. The samples a e ea ed exac ly as moulds and co es being p oduced om he es ed sand. The samples a e no co e ed wi h any p o ec i e coa ings. The samples (co es) a e pu inside he mould wi h usage o special model (sample ). The liquid ound y alloy is pou ed in o he mould. The alloy empe a u e should be he same as i is while p oducing cas s in es ed moulding sand. A e cooling he cas o ambien empe a u e, i is pu – wi h he samples (co es) – in de ice LUW-C o LUW-CA (au o- ∗AGH UNIVERSITY OF SCIENCE AND TECHNOLOGY, FACULTY OF FOUNDRY ENGINEERING, DEPARTMENT OF MOULDING MATERIALS, MOULD TECHNOLOGY AND FOUNDRY OF NON-FERROUS METALS, AL. A. MICKIEWICZA 30, 30-059 KRAKOW, POLAND ∗∗ VSB – TECHNICAL UNIVERSITY OF OSTRAVA, FACULTY OF METALLURGY AND MATERIAL ENGINEERING, DEPARTMENT OF METALLURGY AND FOUNDRY ENGINEERING, CZECH REPUBLIC B ough o you by | Technicka Uni e zi a Os a a Au hen ica ed Download Da e | 12/10/14 3:01 PM 740 ma ically) cons uc ed o measu e moulding sand’s knock-ou p ope ies. The de ice is equipped wi h a pin which knocks he sample (co e) ou he cas . The wo k o one pin bea is 1,63 J [13]. The knock-ou measu emen is he wo k necessa y o mo ing he sample (co e) ou he cas . I is calcula ed om he o mula 1 [13]. Lw=1,63 ·n;J(1) whe e: 1,63 – wo k o one weigh bea , J, n – numbe o weigh bea s ill mo ing he co e ou he cas . The e a e also used o he echnological me hods o mea- su ing moulding sands knock-ou p ope ies including Russian and F ench es s [13]. 2.2. The me hod based on e ained s eng h R k c measu emen The me hod is based on measu emen o e ained s eng h R k cchange o moulding sand wi h hyd a ed sodium silica e wi h empe a u e inc easing. The es begins wi h measu ing s eng h o moulding sand in ambien empe a u e, hen – beginning in 100◦C – he empe a u e is inc easing and he s eng h is being measu ed a e e e y 100◦ ill eaching he empe a u e 1000◦C. A e cooling he samples o ambien empe a u e he e ained s eng h (R k c) o es ed moulding sand is measu ed. The esul s a e pu on he g aph show- ing he in luence o empe a u e on moulding sand’s e ained s eng h (R k c). Acco ding o he eached g aph i ’s possible o es ima e he moulding sand’s knock-ou p ope ies. Good knock-ou p ope ies has he pa o moulding sand hea ed o he empe a u e in which i s e ained s eng h (R k c) is he lowes and he pa o moulding sand hea ed o he empe a u e in which i s e ained s eng h (R k c) is high cha ac e izes wi h bad knock-ou p ope ies [13]. 2.3. The cu e o e ained s eng h (R k c) o moulding sand wi h hyd a ed sodium silica e The e a e h ee ex eme poin s on ypical cu e o e- ained s eng h (R k c) o moulding sand wi h hyd a ed sodium silica e: –The 1s maximum in he empe a u e o abou 200◦C, –The minimum in he empe a u e o abou 600oC, –The 2nd maximum in he empe a u e o abou 800◦C. Mos o he au ho s [13, 15] explain occu ing he 1s maxi- mum as he esul o binde dehyd a ion p ocess and he main ole is assigned o he dehyd a ion o unbound hyd a ed sodi- um silica e. The au ho [15] explains occu ing he 1s max- imum acco ding o DTA cu e o hyd a ed sodium silica e. The cu e shows ha in he ange o empe a u e 350-400◦C begins endo he mic p ocess wi h endo he mic peak egis e ed in he empe a u e o 600◦C. The analysis p o ed he p es- ence o wo endo he mic peaks in empe a u es o 130 and 640◦C is p obably esponsible o he compound dehyd a ion p ocess. Acco ding o he au ho [15] in case o sel ha dened moulding sands p epa ed in es e echnology he 1s maxi- mum doesn’ occu – he e is cons an dec ease o e ained s eng h beginning wi h high alues in ambien empe a u e o he minimum in empe a u e o 600◦C [15]. T ans o ma ion o qua z βα conside ed p e iously as he cause o occu ing he minimum (600◦C) acco ding o he au ho [15] can’ be he only eason o occu ing his ex eme. The au ho p o ed ha moulding sands wi h hyd a ed sodium silica e based on zi conium sand g ains has he minimum in his empe a u e as well. The minimum was also eached by es ing he s eng h o bound hyd a ed sodium silica e wi hou sand g ains. The au ho sugges s ha he e a e di e en ac o s causing his ex eme which a e among all – dehyd a ion p ocesses o dis- odium silica e and silicic acid gel [15]. A e he minimum he e is a apid inc ease o e ained s eng h wi h he max- imum in he empe a u e o 800-900◦C. The 2nd maximum is caused by o ma ion o he liquid phase (mel ing he hy- d a ed sodium silica e) and by he eac ion o Na2CO3wi h SiO2ending wi h o ma ion o Na2O·2SiO2[15]. Beyond he 2nd maximum he e is a apid dec ease o e ained s eng h (R k c) wha J.L. Lewandowski [13] explains as a esul o he iola ion o he binde shell s uc u e on qua z sand g ains, caused by a la ge change in olume o qua z. In he p esence o Na2O con e sion o c is obali e can begin al eady abo e 800◦C. 2.4. The p oposal o new me hod o knock-ou p ope ies’ es ima ion As i was ini ially e e ed in he p e ious pa o he a - icle, he me hod o es ima ion o he knock-ou p ope ies o moulding sands based on e ained s eng h (R k c) measu emen can’ be used in whole empe a u e ange. The use o e ained s eng h measu emen o es ima ion he knock-ou p ope ies o moulding sands is no clea . The au ho [15] p o ed ha moulding sand’s expansion is espon- sible o e ained s eng h dec ease beyond he 2nd maximum. The p ocess is caused by ansi ion o α-SiO2phase in o c is obali e which is ca alyzed by Na+ions, qua z densi y de- c eases om 2650 o 2330 kg/m3wi h inc easing he mass olume o abou 40%. Despi e his moulding sand’s e ained s eng h is low in empe a u es highe han 1000◦C. The au- ho [15] p o ed ha he e is he ypical 2nd maximum in he empe a u e o abou 800◦C on e ained s eng h o mould- ing sands wi h hyd a ed sodium silica e and es e ha dene s cu e, bu he ene gy necessa y o knocking he sample ou while using echnological me hod inc eases ill 1000◦C. The phenomena is caused by c is obali ic qua z sand expansion which is mainly esponsible o e ained s eng h dec ease be- yond he 2nd maximum, inc eases he inal moulding sand’s densi y causing wo se knock-ou p ope ies. Acco ding o his, au ho s o he pape elabo a ed a new me hod o es ima ion o moulding sand’s knock-ou p ope ies. The base was he analysis o co es o moulds beha io du ing pou ing p ocess – he p ocess causes moulding sand expan- sion. Howe e his phenomena is inhibi ed by cas su ace (co e sands) o by cas and moulding box (moulding sands). S ong in e nal s ess occu s in moulding sand which inhibi s i s e acua ion om he cas o om he moulding box. The highe in e nal s ess is he wo se knock-ou p ope ies a e. Moulding sand expansion measu emen a e pou ing p ocess may be use ul o es ima ion o moulding sand’s knock-ou p ope ies. B ough o you by | Technicka Uni e zi a Os a a Au hen ica ed Download Da e | 12/10/14 3:01 PM 741 3. Own esea ch The e we e es ed moulding sands wi h hyd a ed sodi- um silica e and liquid ha dene s p epa ed in sel ha dened moulding sands echnology (es e me hod). The esea ch was conduc ed a e 24h o ha dening wi h keeping cons an em- pe a u e and humidi y in esea ch oom. The au ho s used s anda d and modi ied moulding sands wi h hyd a ed sodium silica e o p o e he necessi y o elabo a ing new me hod o knock-ou p ope ies measu emen . As a ac o modi ying es - ed moulding sands he e we e used own, pa en ed [16] addi i e called Glassex [17]. The ollowing moulding sands composi ions we e aking in o esea ch: •Sand g ains: qua z sand 100 pa s by weigh •Binde : hyd a ed sodium silica e 3 pa s by weigh •Ha dene : lodu 0,3 pa by weigh •Addi i e: Glassex 1 pa by weigh . 3.1. The es ima ion o moulding sands’ knock-ou p ope ies acco ding o Polish S anda d no PN-85/H-11005 As he i s me hod o es ima ion o moulding sands’ knock-ou p ope ies he e was used he me hod acco ding o Polish S anda d no PN-85/H-11005. The e we e es ed mould- ing sands wi h and wi hou Glassex addi i e. In he expe imen he e we e used cylind ical samples. The samples we e pu in expe imen al cas and pou ed wi h cas s eel ha ing he em- pe a u e o abou 1450◦C. A e cooling he cas s we e gen ly knocked ou he mould and he echnological knock-ou p op- e ies measu emen we e ca ied ou . The esul s a e shown in igu e 1 [18]. Fig. 1. Knock-ou p ope ies o moulding sands wi h hyd a ed sodi- um silica e wi h and wi hou Glassex addi i e measu ed by Polish S anda d no PN-85/H-11005 [18] The conduc ed esea ch shows mo e han wice educ ion o wo k necessa y o knocking he co e ou he expe imen al cas while using Glassex addi i e as a componen o moulding sand wi h hyd a ed sodium silica e. 3.2. The es ima ion o moulding sands knock-ou p ope ies acco ding o e ained s eng h R k c measu emen The cylind ical samples (p epa ed like in chap e 3.1) we e hea ed in labo a o y elec ical u nace SNOL 8,2/1100 (P) in he ange o empe a u e 100-1100◦C (e e y 100◦) and in mu le u nace FCF 7 SHM in empe a u e 1200◦C. The samples we e kep in each empe a u e o 15 min and we e cooled wi h he u nace o ambien empe a u e. Then hei e ained s eng h R k cwas measu ed using es ing machine IN- STRON con olled wi h mode n con ol sys em Tes S a IIS. The esul s a e shown in Fig. 2 [19]. Fig. 2. Knock-ou p ope ies o moulding sands wi h hyd a ed sodi- um silica e wi h and wi hou Glassex addi i e es ima ed acco ding o e ained s eng h R k cmeasu emen [19] Inse ing he Glassex addi i e o moulding sands wi h hy- d a ed sodium silica e causes change o hei e ained s eng h R k ccu e shape. The e is no 1s and 2nd maximum on he cu e. Moulding sand wi h Glassex addi i e has lowe e ained s eng h R k cin he ange o empe a u e 200-1000◦C. The in luence o Glassex addi i e on moulding sands knock-ou p ope ies was desc ibed in de ails in p e ious publica ions [19]. The au ho s p o ed ha e ained s eng h R k ccan’ be used as he c i e ia o knock-ou p ope ies es ima ion in he a ea beyond he 2nd maximum – which was desc ibed in he chap e 2.4. Tha ’s why he e is p oposed a new me hod o es ima ion o moulding sand’s knock-ou p ope ies. The me hod is based on high- empe a u e expansion measu emen . 3.3. The es ima ion o moulding sands knock-ou p ope ies acco ding o high- empe a u e expansion measu emen The e we e used cylind ical samples p epa ed and hea ed acco ding o me hods desc ibed in chap e s 3.1 and 3.2. The samples we e measu ed be o e and a e hea ing in he ange o empe a u e 600-1200◦C e e y 100◦acco ding o li e a u e da a [15, 20]. The esul s a e shown in Fig. 3 [19]. B ough o you by | Technicka Uni e zi a Os a a Au hen ica ed Download Da e | 12/10/14 3:01 PM 742 Fig. 3. Knock-ou p ope ies o moulding sands wi h hyd a ed sodi- um silica e wi h and wi hou Glassex addi i e es ima ed acco ding o high- empe a u e expansion measu emen [19] The conduc ed esea ch p o ed ha inse ing he Glassex addi i e o moulding sands wi h hyd a ed sodium silica e caus- es lowing hei high- empe a u e expansion which imp o es hei knock-ou p ope ies. In he empe a u e o 600◦C he high- empe a u e expansion is abou 50% dec eased; 700oC – abou 90%, 800◦C – abou 60%, 900◦C – abou 70%, 1100◦C – abou 50%, 1200◦C – abou 40%. The Glassex addi i e inhibi s high- empe a u e expansion o es ed moulding sands – educes hei in e nal s esses – inc easing hei knock-ou p ope ies. 4. Conclusions Acco ding o li e a u e da a and own esea ch he ollow- ing conclusions may be speci ied: 1. The me hod o es ima ing he knock-ou p ope ies o moulding sands wi h hyd a ed sodium silica e acco ding o hei e ained s eng h R k ccu e beyond he 2nd maximum is no eliable. 2. The me hod o es ima ing he knock-ou p ope ies o moulding sands wi h hyd a ed sodium silica e acco ding o hei high- empe a u e expansion measu emen seems o be much mo e eliable. 3. Inse ing he Glassex addi i e shows o e 50% inc ease o es ed moulding sands knock-ou p ope ies measu ed ac- co ding o hei high- empe a u e expansion. This is con- sis en wi h he esul s o conduc ed echnological me hod. 4. 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