Physico-mechanical and micro-chemical changes on the ceramic and metal artifacts surfaces treated with laser

Чишћење је један од најважнијих процеса у конзервацији предмета културне баштине, али такође и један од најосетљивијих процеса са могућношћу оштећивања оригиналних материјала. Микроморфолошке и микрохемијске анализе на површинама артефаката пре и после процеса чишћења указују на ефикасност методе чишћења, а представљају и користан податак о пореклу и степену деградације артефакта. Значај ласерских техника код чишћења предмета културне баштине почива на особинама ове технике као што су висока осетљивост, недеструктивност, селективност, прилагодљивост, применљивост на лицу места и др. Ове технике се данас широко користе у рестаурацији и чишћењу, архитектонских камених површина. Код других предмета културне баштине (слика, вишебојних папирних докумената, керамичких предмета, стакла, метала, текстила итд.) њихова примена се још увек испитује због комплексног процеса деловања ласерског снопа на ове осетљиве материјале. За безбедно и ефикасно чишћење веома је важно одабрати одговарајуће параметаре ласера и оптимизовати методу ласерског чишћења. Због разноликости материјала који се срећу у културној баштини сваки допринос у овој области је изузетно значајан. У овом раду приказани су принципи методе чишћења ласером, као и резултати примене CO2, Nd:YAG и Er:Glass ласера код чишћења предмета културне баштине од керамике, метала и предмета сложеног састава (комбинације метал-текстил). Испитивања су спроведена на савременим и археолошким узорцима мењањем параметара ласера као што су таласна дужина, број импулса и енергија снопа. За дијагностику микроморфолошких промена на површини озрачених узорака коришћене су оптичка и СЕМ микроскопија. EDX, LIBS, XRF и XRD анализе коришћене су за испитивање хемијског саства узорака и промена састава које, услед деловања ласера, настају у саставу материјала на зонама третираним ласером...Cleaning is one of the most important processes for the conservation of cultural heritage artifacts, but also one of the most delicate and potentially damaging to the original materials. Micromorphological and microchemical analyzes of artefacts surfaces material before and after cleaning process indicates on cleaning effectiveness and can also be useful information for determination of artefacts provenience and degradation degree. Importance of laser techniques in cleaning of cultural heritage objects is based on the properties of these techniques, such as high sensitivity, nondestructivity, selectivity, flexibility, applicability on the spot and others. These techniques are now widely used in the restoration and clean, architectural stone surfaces. In other objects of cultural heritage (picture multicolored paper documents, pottery, glass, metal, textiles, etc.). For reliable and efficient cleaning, selection of the appropriate laser parameters and laser cleaning method optimization is of great significance. Due to the diversity of materials that can be found in cultural heritage, each contribution in this area is extremely important. In this dissertation, the principles of the laser cleaning method, as well as the results of applying the CO2, Nd: YAG and Er:Glass lasers in cleaning of cultural heritage objects made of ceramic, metal and complex (metal-textile combination) materials are presented. Laser cleaning investigations are carried out on contemporary and archaeological samples by varying laser parameters such as wavelength, number of pulses and laser beam energies. For the diagnostics of micromorphological changes on the surface of irradiated samples, optical and SEM microscopy were used. EDX, LIBS, XRF and XRD methods were used for the analysis of changes in samples treated zones chemical compositions caused by lasers irradiation. Measurement of micro and nano hardness was carried out to test the change in the microhardness of the sample after laser action on the surface. By profilometry tests the roughness of the irradiated surfaces of samples before and after irradiation are determined. By image analysis the degree of surface cleaning were determined..

Veza između korozionog potencijala i različitih vidova korozije metala i legura i njihovih zavarenih spojeva - II deo

This paper describes the correlation between the value of the corrosion potential and various types of corrosion of metals and alloys and their welded joints. It is shown that using the method of electrochemical noise is possible to predict the tendency of metals and alloys and their welded joints to different forms of localized corrosion (e.g. pitting corrosion), on the basis of the corrosion potential value. Also, there is a correlation between the value of corrosion potential and the tendency of aluminum alloys to stress corrosion cracking. The correlation between the value of the corrosion potential and the type of corrosion inhibitor is presented. In addition, the correlation between corrosion potential and tendency of stainless steels to pitting corrosion, as well as the tendency of surgical implants to galvanic corrosion was considered. Criteria for sacrificial and active cathodic protection are based on the measurements of corrosion potential. Also, the corrosion behaviour of steel armature in concrete depends on the value of corrosion potential. The susceptibility of metal (steel) constructions and their welded joints to hydrogen embrittlement depends to a considerable extent on the corrosion potential of steel in the given corrosion environment. Due to a large number of applications of corrosion potential measurements, this study is divided into two parts (Part I and Part II).U ovom radu opisana je zavisnost vrednosti korozionog potencijala i različitih vidova korozije metala i legura i njihovih zavarenih spojeva. Pokazano je kako se primenom metode elektrohemijskog šuma, na osnovu vrednosti korozionog potencijala, može predvideti sklonost metala i legura i njihovih zavarenih spojeva prema različitim vidovima lokalizovane korozije, kao što je piting korozija. Takođe je pokazano da se na osnovu vrednosti korozionog potencijala može predvideti sklonosti aluminijumskih legura prema naponskoj koroziji. Ilustrovana je povezanost vrednosti korozionog potencijala i tipa inhibitora korozije. Razmatrana je povezanost korozionog potencijala sa sklonošću nerđajućeg čelika prema piting koroziji, kao i sklonošću hirurških implantanata prema galvanskoj koroziji. Kriterijumi protektorske i aktivne katodne zaštite se zasnivaju na merenju korozionog potencijala. Takođe, stanje armature u betonu se može proceniti na osnovu vrednosti korozionog potencijala. Sklonost metalnih (čeličnih) konstrukcija i njihovih zavarenih spojeva prema pojavi vodonične krtosti u značajnoj meri zavisi od vrednosti korozionog potencijala čelika u datoj korozionoj sredini. Zbog velikog broja primena merenja korozionog potencijala, rad je podeljen na dva dela (deo I i deo II)

Savremene metode laserskog čišćenja predmeta kulturnog nasledja

The monograph presents the results of perennial research of laser application in the cleaning of undesirable layers on cultural heritage objects. Keeping in mind the priceless value of the items that have to be cleaned, research has been carried out with the aim of provide a scientifically based contribution to the safe and efficient application of lasers in conservation laboratories. Laser cleaning is a complex phenomenon that is followed by thermal, mechanical, optical, and chemical effects. Investigation of the laser light interaction with different materials is the first step in the process of successful laser application in the protection of cultural heritage objects. These processes depend on the characteristics of laser irradiation and materials characteristics. The results presented in this monograph included four types of lasers: Nd:YAG, CO2, Er:Glass and ruby laser. Laser irradiation parameters such as beam energy density (fluence), pulse length, number of pulses per second, wavelength and energy distribution within the laser beam are changed. Archaeological objects, samples from museums study collections and samples of contemporary materials (modern ceramics, metals, metal alloys, glass, textiles and a combination of these materials) have been cleaned. Each sample from the cultural heritage collection represents a unique conservation challenge because it has the inherent values of the reflection and absorption coefficients, the chemical and physical properties of the surface, the specific topology at the micro and nano levels, the homogeneity, the thermal expansion coefficient, the melting temperature, and the boiling temperature. Cleaning each of the items requires a proper selection of operating parameters and process control. Morphological and chemical changes in the cleaned zones were examined by optical and SEM microscopy, EDX, XRF, XRD and LIBS analysis. The analysis of cleansing effects includes colorimetric tests, roughness and micro-hardness testing. Other modern methods for monitoring the interaction process (thermography) were also used, and experimental results were processed and verified by numerical methods. Over the past decade, a number of European projects, related to the development and application of new scientific methods and new technologies in the protection of cultural heritage, have been implemented. Our country, rich in cultural heritage, should follow this trend of using modern technology and so in the best way preserve archaeological and cultural heritage for its descendants.U monografiji su prikazani rezultati višegodišnjih istraživanja u oblasti primene lasera u čišćenju nepoželjnih slojeva na predmetima kulturne baštine. Imajući u vidu da baštini pripadaju i predmeti neprocenjive vrednosti, istraživanja su sprovedena s ciljem da se pruži naučno zasnovani doprinos bezbednoj i efikasnoj primeni lasera u konzervatorskim ateljeima. Lasersko čišćenje je kompleksna pojava koju prate toplotni, mehanički, optički i hemijski efekti. Ispitivanje interakcije laserske svetlosti sa različitim materijalima je prvi korak u procesu uspešne primene lasera u zaštiti objekata kulturne baštine. Ovi procesi zavise od karakteristike laserskog zračenja i materijala. Istraživanja, čiji su rezultati prikazani u ovoj monografiji, uključila su četiri tipa lasera: Nd:YAG, CO2, ER:Glass i rubinski laser. Varirani su parametri laserskog zračenja, kao što su gustina energije snopa (fluenca), dužina impulsa, broj impulsa u sekundi, talasna dužina i raspodela energije unutar laserskog snopa. Čišćeni su arheološki predmeti, uzorci iz muzejskih studijskih zbirki i uzorci savremenih materijala (keramika, metali, metalne legure, staklo, tekstil i kombinaciju ovih materijala) kakvi se koriste u savremenoj umetnosti. Svaki uzorak iz zbirke kulturne baštine predstavlja jedinstven konzervacijski problem, jer ima svojstvene vrednosti koeficijenta refleksije i apsorpcije, hemijske i fizičke osobine površine, specifičnu topologiju na mikro i nano nivou, homogenost, koeficijent širenja toplote, temperaturu topljenja i temperaturu ključanja. Čišćenje svakog predmeta zahteva pravilan izbor radnih parametara i kontrolu procesa. Morfološke i hemijske promene u zonama čišćenja, ispitivane su optičkom i SEM mikroskopijom, EDX, XRF i XRD analizom. Dijagnostika efekata čišćenja uključila je i kolorimetrijska ispitivanja, ispitivanja hrapavosti i mikrotvrdoće. Korišćene su i druge savremene metode za praćenje procesa interakcije (termografija), a eksperimentalni rezultati su obrađivani i verifikovani numeričkim metodama. U proteklih desetak godina realizovan je veliki broj evropskih projekata, koji se odnose na razvoj i primenu novih naučnih metoda i novih tehnologija u zaštiti kulturne baštine. Naša zemlja, bogata kulturnim nasleđem, treba da prati ovaj trend korišćenja savremenih tehnologija i tako na najbolji način sačuva arheološko i kulturno nasleđe za budućnost

Polyaniline thin films in sensors for detection of toxic welding vapors

In this paper the possibilities of applying sensors based on filters with surface acoustic waves (SAW) for the detection of harmful products in welding processes are analyzed. This review discusses the sensing mechanism and configurations of the sensors. The principles of SAW sensors are considered with special emphasis on the application of conducting polyaniline nanocomposites as sensitive thin layers in sensors for the detection of CO, NO2, and COCl2. The literature suggests the use of In2O3 as a dopant for CO and NO2 detection sensors, and ethylenediamine and phenylenediamine in COCl2 sensors. The paper presents original results of modeling of sensors that are designed for detection of CO and NO2 for which there are experimental data in the literature. The results obtained based on this model are in excellent agreement with results from the literature, which shows the validity of modeling. Based on the developed modeling methods, calculations were done for sensors for the detection of these gases in which the structure was the surface of quartz. From these modeling results it can be concluded that the use of the quartz substrate provides better sensitivity. In addition, the quartz sensors are thermally stable.U radu su analizirane mogućnosti primene senzora u čijoj osnovi se nalaze filtri sa površinskim akustičkim talasom (PAT), za detekciju štetnih produkata u procesu zavarivanja. Objašnjeni su principi rada PAT senzora sa posebnim osvrtom na primenu elektroprovodnih polianilinskih nanokompozitnih materijala – polianilin/In2O3 i etilendiamin i fenilendiamin polianilinskih nanokompozita kao osetljivih tankih slojeva za detekciju CO, NO2 i COCl2. Prikazan je deo originalnih rezultata modelovanja PAT senzora koji su namenjeni detekciji pomenutih gasova. Rezultati dobijeni na bazi sopstvenog modela poređeni su sa rezultatima iz literature. Pokazano je da se ovim na činom modelovanja može uspešno odrediti koncentracija štetnih gasova u okruženju

Savremene metode laserskog čišćenja predmeta kulturnog nasledja

The monograph presents the results of perennial research of laser application in the cleaning of undesirable layers on cultural heritage objects. Keeping in mind the priceless value of the items that have to be cleaned, research has been carried out with the aim of provide a scientifically based contribution to the safe and efficient application of lasers in conservation laboratories. Laser cleaning is a complex phenomenon that is followed by thermal, mechanical, optical, and chemical effects. Investigation of the laser light interaction with different materials is the first step in the process of successful laser application in the protection of cultural heritage objects. These processes depend on the characteristics of laser irradiation and materials characteristics. The results presented in this monograph included four types of lasers: Nd:YAG, CO2, Er:Glass and ruby laser. Laser irradiation parameters such as beam energy density (fluence), pulse length, number of pulses per second, wavelength and energy distribution within the laser beam are changed. Archaeological objects, samples from museums study collections and samples of contemporary materials (modern ceramics, metals, metal alloys, glass, textiles and a combination of these materials) have been cleaned. Each sample from the cultural heritage collection represents a unique conservation challenge because it has the inherent values of the reflection and absorption coefficients, the chemical and physical properties of the surface, the specific topology at the micro and nano levels, the homogeneity, the thermal expansion coefficient, the melting temperature, and the boiling temperature. Cleaning each of the items requires a proper selection of operating parameters and process control. Morphological and chemical changes in the cleaned zones were examined by optical and SEM microscopy, EDX, XRF, XRD and LIBS analysis. The analysis of cleansing effects includes colorimetric tests, roughness and micro-hardness testing. Other modern methods for monitoring the interaction process (thermography) were also used, and experimental results were processed and verified by numerical methods. Over the past decade, a number of European projects, related to the development and application of new scientific methods and new technologies in the protection of cultural heritage, have been implemented. Our country, rich in cultural heritage, should follow this trend of using modern technology and so in the best way preserve archaeological and cultural heritage for its descendants.U monografiji su prikazani rezultati višegodišnjih istraživanja u oblasti primene lasera u čišćenju nepoželjnih slojeva na predmetima kulturne baštine. Imajući u vidu da baštini pripadaju i predmeti neprocenjive vrednosti, istraživanja su sprovedena s ciljem da se pruži naučno zasnovani doprinos bezbednoj i efikasnoj primeni lasera u konzervatorskim ateljeima. Lasersko čišćenje je kompleksna pojava koju prate toplotni, mehanički, optički i hemijski efekti. Ispitivanje interakcije laserske svetlosti sa različitim materijalima je prvi korak u procesu uspešne primene lasera u zaštiti objekata kulturne baštine. Ovi procesi zavise od karakteristike laserskog zračenja i materijala. Istraživanja, čiji su rezultati prikazani u ovoj monografiji, uključila su četiri tipa lasera: Nd:YAG, CO2, ER:Glass i rubinski laser. Varirani su parametri laserskog zračenja, kao što su gustina energije snopa (fluenca), dužina impulsa, broj impulsa u sekundi, talasna dužina i raspodela energije unutar laserskog snopa. Čišćeni su arheološki predmeti, uzorci iz muzejskih studijskih zbirki i uzorci savremenih materijala (keramika, metali, metalne legure, staklo, tekstil i kombinaciju ovih materijala) kakvi se koriste u savremenoj umetnosti. Svaki uzorak iz zbirke kulturne baštine predstavlja jedinstven konzervacijski problem, jer ima svojstvene vrednosti koeficijenta refleksije i apsorpcije, hemijske i fizičke osobine površine, specifičnu topologiju na mikro i nano nivou, homogenost, koeficijent širenja toplote, temperaturu topljenja i temperaturu ključanja. Čišćenje svakog predmeta zahteva pravilan izbor radnih parametara i kontrolu procesa. Morfološke i hemijske promene u zonama čišćenja, ispitivane su optičkom i SEM mikroskopijom, EDX, XRF i XRD analizom. Dijagnostika efekata čišćenja uključila je i kolorimetrijska ispitivanja, ispitivanja hrapavosti i mikrotvrdoće. Korišćene su i druge savremene metode za praćenje procesa interakcije (termografija), a eksperimentalni rezultati su obrađivani i verifikovani numeričkim metodama. U proteklih desetak godina realizovan je veliki broj evropskih projekata, koji se odnose na razvoj i primenu novih naučnih metoda i novih tehnologija u zaštiti kulturne baštine. Naša zemlja, bogata kulturnim nasleđem, treba da prati ovaj trend korišćenja savremenih tehnologija i tako na najbolji način sačuva arheološko i kulturno nasleđe za budućnost

Formiranje i rast pitova na austenitnom nerđajućem čeliku X5CrNi18-10 u prisustvu hlorida i sulfata

The resistance of X5CrNi18-10 stainless steel to pitting corrosion in a solution containing chlorides and sulphates was tested using the potentiodynamic polarization method. The obtained results show that the stainless steel is significantly resistant to pit formation, but it is susceptible to pit growth and crevice corrosion. Pits formed at the corrosion potential grow continuously. Statistical analysis of the results obtained during pitting corrosion testing was performed. It can be assumed with a probability of 95% that values of indicators of resistance to pit formation (the pitting potential Epit, the metastable pitting potential Empit and the difference Epit-Ekor) will be within the range of several percents. Values of indicators of resistance to pit growth (the amount of charge required for the pit growth q, the protective potential Eprot and the difference Epit-Eprot) will be within the broader range. In addition, the appearance of pits on the surface of the stainless steel, as well as the appearance of the pits bottom, were analyzed. It was shown that the structure of the stainless steel tested was not sensitized to pitting and intergranular corrosion, which means that the stainless steel was not previously thermally treated.Primenom potenciodinamičke metode ispitana je otpornost nerđajućeg čelika X5CrNi18-10 na piting koroziju, u rastvoru koji sadrži hloride i sulfate. Dobijeni rezultati pokazuju da je nerđajući čelik u značajnoj meri otporan prema formiranju pitova, ali postoji sklonost prema rastu pitova i koroziji u zazorima. Pitovi formirani na korozionom potencijalu nastavljaju stabilno da rastu. Izvršena je statistička analiza rezultata dobijenih pri ispitivanju piting korozije. Pokazano je da će se sa verovatnoćom od 95 % vrednosti pokazatelja otpornosti nerđajućeg čelika prema formiranju pitova (potencijal pitinga Epit, potencijal metastabilnog pitinga Empit i razlika Epit-Ekor) nalaziti u granicama od nekoliko procenata. Vrednosti pokazatelja otpornosti nerđajućeg čelika prema rastu pitova (količina naelektrisanja potrebna za rast pitova q, zaštitni potencijal Eprot i razlika Epit-Eprot) će se nalaziti u širim granicama. Pored navedenog, analiziran je izgled pitova na površini nerđajućeg čelika, kao i izgled dna pitova. Pokazano je da struktura ispitivanog nerđajućeg čelika nije senzibilizovana prema piting i interkristalnoj koroziji, odnosno da nerđajući čelik nije bio prethodno termički tretiran

Turbulence recognition in free convective flow by thermal-video post-processing in the case of a thermal power plant mill

This paper presents a study of a free convection flow around the walls of a ventilation mill of the Thermal Power Plant "Kostolac B", Kostolac, Serbia. A combined method consists of thermography and software post-processing, PATS. The PATS is specially developed for recognition of turbulence zones by the custom processing of large input data sets from thermal videos. The calculations determine maximum temperature fluctuation i.e. peak-to-peak fluctuation at every spot during the recording time. Three thermal videos of the walls were analyzed. Maximum temperature fluctuation occurred in the zones close to the obstacles, which are thus recognized as one of the main sources of turbulence. Besides, PATS has recognized fine camera oscillations and mechanical movements of a flexible material near the dozer wall. The detected zones of turbulence correspond to the previous studies and to the theory. The method shows good potential in the field of free convective flow research through the improvement of testing efficiency and cost savings. State-of-the-art thermograph cameras and updated software are recommended

Surface modification on iron induced by Nd:YAG pulsed laser treatment

The modern military industry demands the most innovative and high-quality metals and alloys, as well as processing technologies. Iron and its alloys are a common material used for different types of weapons and military equipment. Lasers have been widely used in the metal surface processing, but the changes that occur on laser treated metal surfaces have not yet been sufficiently investigated. A study of morphological and chemical changes on the metal surface induced by Nd:YAG laser treatment in ambient air is presented. A pulsed Nd:YAG laser (1064 nm, Gaussian spatial profile, FWHM 8 ns, energy up to 525 mJ, beam diameter of 1-10 mm and fluence up to 3.5 J/cm 2 ) was used. Micro-morphological analyses of sample surfaces before and after laser treatment process were performed by optical and SEM microscopies. EDX method was used for chemical analyses and Spectra colorimeter for investigation of induced color changes. The laser irradiation effects were studied as a function of two laser parameters, number of laser pulses and laser fluencies, around and over the damage threshold. The results show that there are significant differences depending on these laser parameters

Determination of Nd-Yag laser parameters for metal threads cleaning in textile artefacts

Textile samples with metallic threads from the collection of the Ethnographic Museum in Belgrade were subjected to Nd: YAG laser irradiation in order to determinate certain parameters for successfully and safely clean corrosion products without degrading the surrounding material. Application of conventional cleaning methods did not give the expected results, and the implementation of laser technology was the next step. The Nd: YAG laser energy 150mJ (1064 nm) and 50 mJ (532 nm) and pulse width 150 ps was used. The commercial, Thunder Art Laser was also used. Effects of the irradiated areas was investigated by optical and SEM microscopy and EDX analysis

Истраживање лиминалних феномена у ласерском чишћењу историјског папира

Феномени лиминалности прате ласерско чишћење историјског папира, од фазе планирања поступка, до завршетка његовог извођењ. Реч је о појавама различитог порекла и начина испољавања, које могу бити доминантне или мање експониране, а свакако једнако значајне за целовитост и квалитет изведеног поступка. У овом раду фокус истраживања је проблематизацији лиминалности, као и артикулација и трансформабилност. Задати референтни оквир представља један од могућих скупова феномена који се у оквиру ласерског чишћења могу сагледавати и у ширим контекстима