Razvoj in analiza frit za emajliranje aluminijevih zlitin

doktorska disertacija

Mitja Bukovec (Author), Matjaž Finšgar (Mentor)

Abstract

Doktorska raziskava je temeljila na razvoju frit za emajliranje aluminijevih zlitin, saj je uporaba zlitin zaradi njihove nizke cene, nizke gostote in odlične trdnosti vedno večja. Tako se aluminijeve zlitine uporabljajo v različnih panogah, vendar je njihova uporaba omejena zaradi njihove visoke kemijske aktivnosti in potencialno slabe korozijske odpornosti v kislih, alkalnih in kloridnih raztopinah. Študija je zajemala raziskave različnih surovin ter oksidne sestave frit. %Da smo dobili homogen granulat, smo za posamezno frito določili optimalne pogoje časa in temperaturo taljenja. S talilnim mikroskopom smo opazovali površino in določili štiri talilne točke: sintranja, zmehčanja, polkrogle in stekanja. Razteznostni koeficient frite smo določili z dilatometrom, ter ga primerjali z razteznostnim koeficientom posamezne aluminijeve zlitine.%Pred emajliranjem smo vzorce zlitin očistili in nekatere tudi zbrusili, da bi ugotovili vpliv predhodne obdelave zlitine na vezavo emajla. Pripravljenih je bilo več frit, med katerimi je bilo sedem frit, s katerimi smo emajlirali tri vrste aluminijevih zlitin in sicer AA2024, AA6082 in AA7075. Za posamezno frito smo določili optimalne pogoje časa in temperaturo žganja. Korozijska odpornost emajliranih vzorcev je bila preizkušena v 5-odstotni raztopini NaCl pri sobni temperaturi z uporabo meritev elektrokemijske impedančne spektroskopije in meritev krivulj ciklične polarizacije. Korozijska odpornost emajliranih vzorcev se je v primerjavi z neemajliranimi aluminijevimi zlitinami povečala.%Sestava, površinska in globinska homogenost dveh najučinkovitejših emajliranih vzorcev sta bila potrjena z uporabo FE-SEM posnetkov, jedkanja z ionskim izvorom klastrov argona in z kvantitativno analizo z uporabo rentgenske fotoelektronske spektroskopije. Dodatno je bila za opis 3D sestave frit uporabljena tehnika masne spektrometrije sekundarnih ionov z detektorjem na čas preleta in jedkanjem z uporabo ionskega izvora O2+. Globino nastalega kraterja pri globinskem profiliranju smo analizirali z uporabo 3D profilometra.

Keywords

frita;emajl;emajliranje;korozija;elektrokemija;3D profilometrija;doktorske disertacije;

Data

Language:	Slovenian
Year of publishing:	2021
Typology:	2.08 - Doctoral Dissertation
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[M. Bukovec]
UDC:	620.193.4:669.715(043.3)
COBISS:	59287811
Views:	479
Downloads:	66
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Development and analysis of frits for enamelling of aluminum alloys
Secondary abstract:	The doctoral dissertation was based on the development of frit for enamelling aluminium alloys, as the use of alloys is increasing due to their low price, low density and excellent strength. Thus, alluminium alloys are used in various industries, but their use is limited due to their high chemical activity and potentially poor corrosion resistance in acidic, alkaline and chloride solutions. The study included research on various raw materials and the oxide composition of frit. In order to obtain a homogeneous granulate, the optimal time conditions and melting temperature were determined for each frit. The surface was observed with a heating microscope; moreover, the four melting points of the frits were determined: sintering, softening, half-sphere and melting. In addition, the thermal expansion coefficient of each frit was determined with a dilatometer and compared with the thermal expansion coefficient of the particular aluminium alloy.Prior to enamelling, alloy samples were cleaned and some were sanded to determine the effect of alloy preatreatment on enamel bonding. Several frits were prepared, of which seven were coated on three types of aluminium alloys: AA2024, AA6082, and AA7075. Optimal time conditions and the firing temperature were determined for each frit. The corrosion resistance of the coated samples was tested in a 5 wt. NaCl solution at room temperature using the electrochemical impedance spectroscopy and cyclic polarization measurements. The corrosion resistance of the enamelled samples increased compared to the respective noon-enamelled aluminium alloys. The composition, surface and depth homogeneity of the two most efficiently enamelled samples were confirmed using FE-SEM images, sputtering with an ion-surce clusters of argon and by the quantitative analysis using X-ray photoelectron spectroscopy. Additionally, the technique of mass spectrometry of secondary ions with a time-of-flight detector and sputtering using an O2+ source was used to describe the 3D composition of the frits. The depth of the formed crater was analyzed using a 3D profilometer.
Secondary keywords:	frit;enamel;aluminium alloy;corrosion;electrochemistry;XPS;ToF-SIMS;3D profilometry;Aluminijeve zlitine;
Type (COBISS):	Doctoral dissertation
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	XII, 116 f.
ID:	12258015