Istraživanje korozije u procesima grafičke reprodukcije

Dragčević, Krešimir (2010) Istraživanje korozije u procesima grafičke reprodukcije. Dissertation (PhD) thesis. Grafički fakultet. [Mentor: Lovreček, Mladen].

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Abstract

Korozija u realnim tiskarskim sustavima dobro je poznata pojava, premda istraživanjima njenih uzoroka i posljedica do sada nije posvećena dovoljna pozornost. U ovom radu je kroz tri faze istraživanja ispitan utjecaj pojedinih kemijskih i fizikalnih parametara otopina za vlaženje na koroziju laboratorijskog čelika DIN Ust 12 (Cmax 0,12%, Mnmax 0,50%, Pmax 0,04%, Smax 0,04%). U prvoj fazi istraživanja pratio se utjecaj različitih pH vrijednosti te sastava elektrolita na koroziju čeličnih uzoraka u otvorenom sustavu, u kojem je omogućena apsorpcija kisika u elektrolit tijekom 126 dana. U primjeni ekoloških koncentrata otopina za vlaženje u suvremene sustave ofsetnog tiska dolazi do izraženije pojave korozije. Stoga se u drugoj fazi istraživanja pratio utjecaj konvencionalnih i ekoloških otopina za vlaženje te utjecaj otopljenih površinskih spojeva papira na koroziju čeličnih uzoraka u zatvorenim sustavima kroz približno 31 mjesec. U prve dvije faze istraživanja kvantitativno se korozija pratila gravimetrijski, sa površina čelika snimana je spektrofotometrijska reemisija elektromagnetskog zračenja u vidljivom dijelu spektra, a FT-IR spektrometrijom analizirani su korozijski produkti iz taloga elektrolita. U trećoj fazi provedena su elektrokemijska potenciodinamička ispitivanja tehnikama s istosmjernom strujom, metodama linearne polarizacije i Tafelove ekstrapolacije kojima su određeni korozijski parametri: korozijski potencijal (Ekor/mV), gustoća korozijske struje (jkor/μA cm-2), polarizacijski otpor (Rp/Ω cm2βk) i anodni (βa) nagib Tafelovih pravaca te brzina korozije (BK /mm god-1). U trećoj fazi istraživanja mjerenjima je ispitan utjecaj različitih industrijskih otopina i otopljenih površinskih spojeva na koroziju čelika. Dobiveni rezultati svim primijenjenim mjernim metodama ukazuju da je korozija u početnim konvecionalnim i ekološkim otopinama za vlaženje pri sobnoj temperaturi gotovo potpuno inhibirana, dok bitno veći utjecaj na tijek i dinamiku korozije imaju površinski spojevi papira otopljeni u otopini za vlaženje tijekom procesa tiska.

Item Type:	Dissertation (PhD) thesis
Mentor name:	Lovreček, Mladen
Thesis Committee:	Bolanča, Stanislav and Lovreček, Mladen and Džimbeg-Malčić, Vesna and Stupnišek-Lisac, Ema and Ristić, Mira and Knešaurek, Nina and Antonić Jelić, Tatjana
Defence date:	22 December 2010
Abstract in english:	Corrosion in real printing systems is well known phenomenon, although ample attention has not been given by now to the investigations of its origins and consequences. In this thesis, the influence of certain chemical and physical parameters of fountain solutions on the corrosion of laboratory steel DIN Ust 12 (Cmax 0,12%, Mnmax 0,50%, Pmax 0,04%, Smax 0,04%) has been investigated in three phases. In the first phase, the influence of different pH values, as well as the compositions of electrolytes on the corrosion of steel specimens in the open system - with enabled absorption of oxygen in the electrolyte - was followed during 126 days. With the application of ecological concentrates of fountain solutions, the phenomenon of corrosion becomes more significant. In the second phase, therefore, the impact of conventional and ecological fountain solutions, as well as the impact of dissolved surface compounds from the paper on the corrosion of the steel was followed in the closed systems during approximately 31 months. The corrosion was in the first two phases quantitatively determined by gravimetric method, the spectrophotometer reemission of the electromagnetic radiation was registered from the surface of the steel in the visible part of the spectrum, while the corrosion products were analyzed from the electrolyte residues by the FT-IR spectrometry. In the third phase the electrochemical potentiodynamic measurements were carried out with the direct current and the method of linear polarization and Tafel’s extrapolation, by which the corrosion parameters were determined: corrosion potential (Ekor/mV), corrosion current density (jkor/μA cm-2), polarization resistance (Rp/Ω cm2) cathodic (-βk) and anodic (βa) inclination of Tafel’s lines, as well as the corrosion rate (BK /mm yr-1). In the third phase, the impact of different industrial fountain solutions and dissolved paper surface compounds on the corrosion was measured. Results obtained by the applied measuring methods are showing that the corrosion in the starting conventional and ecological fountain solutions is almost totally inhibited at the room temperature, while compounds from the surface of the paper, dissolved in the fountain solution, have significantly higher impact on the course and the dynamics of the corrosion during the printing process.
Uncontrolled Keywords:	korozija, čelik, otopina za vlaženje, FT-IR, linearna polarizacija, Tafelova ekstrapolacija
Keywords in english:	corrosion, steel, fountain solution, FT-IR, linear polarization, Tafel’s extrapolation
Subjects:	TECHNICAL SCIENCES > Graphic Technology
Institution:	Grafički fakultet
City:	Zagreb
Number of Pages:	129
Callnumber:	655.3 dra d
Inventory number:	8860
Status:	Unpublished
Date Deposited:	15 Nov 2013 21:47
Last Modified:	29 Apr 2014 09:52
URI:	http://eprints.grf.unizg.hr/id/eprint/1430

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