How to Avoid Chemical Agresive Substances in Waste Waters From Gold Jewel Production

Kovačević, Zorica

doi:10.5593/sgem2011/s20.135

Cited by 2 publications

(4 citation statements)

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“…The filler metal for a particular application is chosen based on its ability to: wet the base metals, see Fig. 2a, and melt at a lower temperature than the base metals [7][8][9][10].…”

Section: Cracks At Leafmentioning

confidence: 99%

“…2a. Excess flux should be removed when the cycle is completed, because flux left in the joint may have led to generate the corrosion, and prevent next surface finishing operation(s) [8].…”

Section: Cracks At Leafmentioning

confidence: 99%

“…Those factors are leading to the appearance of crack(s) in the joint. If the crack is registered just after brazing process is finished, it is immediatly visible and of course could be removed [7,8]. The problem is more complex when crack(s) begun visible after a long period, as sometime happened in artistic components.…”

Section: Introductionmentioning

confidence: 99%

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Corrodive cracks from flux residuals after brazing of thin leaves at an artistic desk lamp

Karastojković¹,

Polić²,

Čubrilović³

et al. 2018

Zaštita materijala

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Making of an artistic piece usually includes a number of different technologies. It implies that for understanding of eventually present irregularities one should knows a lot of technical details. Brazing tehnology is one of them, inspection of integrity, also. Brazing technology generally has evolved on empirical manner, mainly by trial and error(s). The basic difficulty in this technology is that the real situation is highly complex due to the presence of large number of variables, some of them may not be easy to recognize. The great problem is the appearance of crack(s) in postcleaning periode, i.e after brazing is finished, it means over years or decades. A good braze joint must be both physically and chemically bounded. One of the available method for investigation is radiographic testing, when the thickness of testing components commonly does not represents a problem. Here provided radiographic testing has revealed the existence of some indications only at leaves. The indications usualy mean discontinuity in material homogenity. Penetrant testing is a next step for investigation of surface. Registration of indications and their locations are necessary steps in any further approach for removing such discontinuities. Choosing the repair method always is particular problem, however in entire technique, especially on sensitive artistic component(s). Every action in repairing or restauration may led to more or less visible traces. Unadequate actions may permanently change the appearance or usage of treated artefact. Here is shown one irregularity (crack) at one brazed leaf from an artistic desk lamp.

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“…The filler metal for a particular application is chosen based on its ability to: wet the base metals, see Fig. 2a, and melt at a lower temperature than the base metals [7][8][9][10].…”

Section: Cracks At Leafmentioning

confidence: 99%

“…2a. Excess flux should be removed when the cycle is completed, because flux left in the joint may have led to generate the corrosion, and prevent next surface finishing operation(s) [8].…”

Section: Cracks At Leafmentioning

confidence: 99%

See 1 more Smart Citation

Corrodive cracks from flux residuals after brazing of thin leaves at an artistic desk lamp

Karastojković¹,

Polić²,

Čubrilović³

et al. 2018

Zaštita materijala

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“…Međutim, realni uslovi proizvodnje primenjene legure su daleko od ravnotežnih, bilo u procesu livenja ili u nekim drugim postupcima obrade i prerade [13][14][15].…”

Section: Slika 3 -Idealne Difrakcije I Intenziteti Rentgenskih Zraka unclassified

X-ray diffraction analysis of cold rolled strip from jewelry 585 gold alloy

Karastojković¹,

Perić²,

Janjušević³

et al. 2017

Tehnika

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UVODTehnologije obrade deformisanjem, kao ovde hladno valjanje, prilično su zastupljene u proizvodnji elemenata zlatnog nakita. Valjanje tankih limova i traka preovlađuje u juvelirskoj proizvodnji [1,2], ali ne i u proizvodnji valjane žice, kao što je slučaj u masovnoj proizvodnji čelika, bakra i aluminijuma. Zbog prirode juvelirskih proizvoda, konačne debljine limova od legura zlata, uključujući i predmetnu leguru 585 (min. 58,5% Au), često su manje od 1 mm. Ovakvi limovi se dalje nekim od postupaka plastičnog deformisanja moraju oblikovati do željenog proizvoda, nakita.U postupcima prerade i/ili oblikovanja legura zlata moguća je pojava izvesnih strukturnih promena, koje kasnije mogu da dovedu čak do loma proizvoda, što je uvek neželjena pojava naravno i u legurama zlata [2][3][4]. Jedan od čestih i pouzdanih pristupa u izučavanju strukturnih promena u materijalu predstavlja rendgensko ispitivanje, tačnije primena rendgenske difrakcione analize.U literaturi postoje brojni podaci o pojedinim ravnotežnim fazama iz sistema Au-Ag-Cu, koje su dobijene posle zaista detaljne pripreme, npr. žarenja na povišenoj temperaturi (od 300 o C ili slično) u trajanju od preko 20 dana [5,6]. Ali, ovakav režim rada i ispitivanja je neprimeren bilo kakvoj proizvodnji, pa bila to i poluindustrijska proizvodnja legura zlata, kao u ovom slučaju. Može se slobodno reći da zbog "tajnovitosti zanata" mnogi podaci o karakteristikama legura zlata u različitim fazama nisu objavljivani, time nisu poznati. Juvelirske legure zlata obično nisu bile predmet detaljnijih ispitivanja.Mnogi od davnina i dan-danas pristupaju obradi legura zlata po principu "crne kutije", a to se svodi na slabo poznavanje nastalih procesa i fenomena u materijalu, pogotovu kada su u pitanju fazne transformacije u čvrstom stanju [7][8][9]. Za ovakve promene Z. KARASTOJKOVIĆ i dr.RENDGENSKA DIFRAKCIONA ANALIZA HLADNO... 54TEHNIKA -RUDARSTVO, GEOLOGIJA I METALURGIJA 68 (2017) 1 u čvrstom stanju, ipak, merodavna su metalografska, kao i rentgenska difrakciona ispitivanja [9, 10].2. OČEKIVANA STRUKTURA U RAVNOTEŽNIM USLOVIMA Struktura obrađivanog materijala uvek je zavisna od uslova (parametara) prerade i/ili obrade. Izučavanje trokomponentnog dijagrama stanja sistema Au-Ag-Cu se zasniva na binarnom dijagramu Au-Cu, sl. 1. Slika 1 -Dijagram stanja binarne legure Au-Cu sa spinodalnom reakcijom razlaganja [2]Iz dijagrama se može videti položaj korišćene legure sa 58,5% Au. Sa istog dijagrama Au-Cu još se može videti da se ispod krive likvidusa javlja homogeni čvrsti rastvor (α), koji se nakon hlađenja razlaže po mehanizmu spinodalnog razlaganja u čvrstom stanju [4].Mehanizmi spinodalnog razlaganja se potpunije tumače u odgovarajućoj stručnoj literaturi [8][9][10]. Ispitivanu leguru zlata 585, saglasno ravnotežnom dijagramu stanja, karakterišu dva osnovna stanja kristalne strukture [4,7]: haotični raspored, koji se pripisuje homogenom alfa-čvrstom rastvoru, i sređenom rasporedu, u kojem učestvuju dve faze (AuCuI i AuCuII), saglasno dijagramu stanja, sl. 1.Dijagram stanja sa ove...

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How to Avoid Chemical Agresive Substances in Waste Waters From Gold Jewel Production

Cited by 2 publications

References 0 publications

Corrodive cracks from flux residuals after brazing of thin leaves at an artistic desk lamp

Corrodive cracks from flux residuals after brazing of thin leaves at an artistic desk lamp

X-ray diffraction analysis of cold rolled strip from jewelry 585 gold alloy

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