Poly(vinyl butyral)/nano-silver as a multifunctional coating for textile

This research considers a possibility to enhance the mechanical and spectrophotometric properties of a military camouflage cotton textile by applying a nano silver/poly(vinyl butyral), PVB, impregnation. Silver is known for its unique optical, electrical, thermal properties and antimicrobial activity[1]. PVB is chosen as a good impregnating matrix, being a thermoplastic elastomer with good adhesion behavior, resistant to wetting [2]. Impregnated fabric samples were examined regarding spectrophotometric properties and mechanical abrasion resistance. To achieve low visibility, besides being painted to match the colors of the environment, a surface must scatter light, so it should have a matte, low gloss coating [3, 4]. Diffuse reflectance and gloss are related, and from a spectral point of view, scattering properties are relevant for surface appearance [5]. Certain nanostructures may alter this feature

Cavitation resistance of explosively welded aluminium/steel joint

Explosion welding is an unconventional method of joining two dissimilar metal materials, mostly used to clad dissimilar materials or when some unusual geometries need to be joined. Some of the bimetal joints obtained this way have applications in special cutting tools, transition joints, propellers and turbine blades, and therefore it is important to know the wear resistance of welded joints. In this research, explosive Demex, based on ammonium nitrate and trinitrotoluene, was used to weld plates of aluminium alloy AW-2024 and steel 1.0216. The welding procedure was carried out in the configuration of parallel plates. The quality of the welded joint was inspected on samples cut out from the welded plate by the method of microscopic analysis on the cross-section and by an ultrasonic cavitation test. Materials erosion in the zone of the welded joint after each of 4 cavitation cycles was observed using an optical microscope and by monitoring the mass loss. The wear resistance of the created bimetal was analysed from the aspects of further exploitation

Properties of aluminum-steel plates explosively welded using Amonex explosive

Besides their application in munitions and armaments, explosives have a significant role in industrial applications, such as cladding or welding of metal plates. In the process of explosion welding, the energy of explosive detonation is used to achieve a metallurgical bond between two metal components, which are metallurgically compatible, but also those that are non-weldable by conventional methods. For this purpose, most often explosives of low values of detonation velocity are used, in order to avoid severe damage to the processed metal plates. The aim of this study was to investigate the possibility to use the industrial explosive Amonex, which belongs to a group of low-to-middle detonation velocity explosives, for welding of metallic materials. It consists of ammonium nitrate and TNT as energetic components and other inert ingredients and has a powdery consistency, easily applicable in a desirable layer over the metal plates to be welded. Within this research, Amonex was applied to weld plates of aluminium Al 2024 and steel Č0345. Besides the initial data on the used metal plates, the main properties of the used explosives are also given, since based on these properties the needed quantity of explosive was estimated. The procedure of welding was carried out in the configuration of parallel plates, and afterward the welded joint was examined. Ultrasonic method and chemical penetrants were used as non-destructive techniques, and then the samples were cut from the welded plate using water-jet, in order to perform microscopic analyses on the cross-section and to determine the indentation hardness in the area of the joint. It was observed that a good-quality welded joint was obtained, and that the selected explosive may find further application in this area

Changes in the infrared attenuated total reflectance (ATR) spectra of lignins from alfalfa stem with growth and development

Lignin is a poorly characterized polymer and its exact properties vary depending on both the species of the plant and its location within the plant. Three classes of lignins taken from alfalfa stem were examined. The investigation was concentrated on the determination of chemical changes in the lignins during growth and development by the attenuated total reflectance (ATR) infrared (IR) spectrometric technique. The spectrum of permanganate lignin was comparable to that of acid detergent lignin. The main differences were in the different relative absorbance of the peaks. The predominant component of acid detergent lignin and permanganate lignin was guaiacyl-type lignin. The predominant component of Klason lignin was syringyl-type lignin. A comparison between the signals from lignin in different development stages revealed the appearance of new peaks, which are indications of new bonds and changes in the structure of the lignins

Mechanical properties of laminate materials based on polylactic acid and polyvinyl chloride meshes as reinforcement

The 3D printing parameters are known to have a significant impact on manufactured parts, and the layered morphology of these parts makes mechanical design analysis for engineering applications difficult. In this work, the tensile strengths and microhardness of 3D printed polylactic acid (PLA) specimens with different orientations and numbers of individual layers of mesh material (polyvinyl chloride – PVC) were investigated as a laminate composite. Composite specimens were obtained using 3D printing via fused deposition modelling (FDM). Moreover, the influence of printing parameters (i.e. infill density and layer height) and the number and orientation of reinforced meshes on the mechanical response was investigated. Fracture strength of PLA/PVC laminate composites ranges from 31.30 MPa (3 PVC mesh layers; mesh height position: 25 % │ 50 % │ 75 %; infill density: 60 %; PVC mesh orientation: 90° │ 45° │ 90°; layer height: 0.2 mm) to 18.62 MPa (without PVC mesh; infill density: 30 %; layer height: 0.1 mm) demonstrating a significant impact of the number of the PVC mesh layers, infill density of PLA and layer height on the final mechanical parameters of printing PLA/PVC elements. The surface hardness at the micro load level showed that the number of reinforcement layers affects the microhardness value, as well as material filling and mesh orientation. The specimen with the following parameters gave the best results: layer height: 0.2 mm; 3 PVC mesh layers; infill density: 60 %; PVC mesh orientation: 90° │ 45° │ 90°. The average hardness values for one layer and three layers of mesh were in accordance with tensile test results

Sagorevanje otpadnog termobaričnog eksploziva pod kontrolisanim uslovima kao izvor energije

Thermobaric explosive mixtures are recently widely studied due to their specific energetic effects, especially regarding thermal output during the post-detonation combustion phase. Most of these mixtures contain as a very important component some metal powder fuel, which burns in contact with atmosphere oxygen or the oxidant component of the mixture after the initiation. This combustion process releases a large amount of thermal energy, which is recognized as a potential source of other types of energy if it were released and further transformed under controlled conditions. In this research, the possibility of controlled combustion of waste thermobaric explosives as a source of energy was considered. Thermobaric compositions containing aluminium, magnesium and boron powder were analysed. EXPLO5 software was used to calculate parameters of their isochoric and adiabatic combustion, to predict the potential thermal output of these mixtures. The selected compositions were experimentally examined in small samples by the method of calorimetry to determine their energetic potential during combustion in atmosphere of inert gas in a calorimetric bomb. The obtained results encourage further research into the possible applications of this thermal energy, which can be released not only in the reaction of a destructive explosion, but also by combustion under controlled conditions, as a quaternary recycling of waste explosives - a potential source of heat and electric energy.Termobarične eksplozivne smeše su u poslednje vreme dosta proučavane zbog specifičnih energetskih efekata, posebno u pogledu toplotnog dejstva tokom faze post-detonacionog sagorevanja. Većina ovih smeša sadrži kao veoma važnu gorivnu komponentu neki metalni prah koji nakon iniciranja sagoreva u kontaktu sa atmosferskim kiseonikom ili oksidatorskom komponentom smeše. Ovaj proces sagorevanja oslobađa veliku količinu toplotne energije, koja je prepoznata kao potencijalni izvor drugih vidova energij ukoliko bi se oslobađala i dalje transformisala pod kontrolisanim uslovima. U ovom istraživanju razmotrena je mogućnost kontrolisanog sagorevanja otpadnog termobaričnog eksploziva kao izvora energije. Analizirane su termobarične smeše koje sadrže prah aluminijuma, magnezijuma i bora. Za izračunavanje parametara njihovog izohorskog i adijabatskog sagorevanja korišćen je softver EXPLO5, za predviđanje potencijalnog toplotnog efekta ovih smeša. Odabrani sastavi su eksperimentalno ispitani metodom kalorimetrije na malim uzorcima kako bi se utvrdio njihov energetski potencijal pri sagorevanju u atmosferi inertnog gasa u kalorimetrijskoj bombi. Dobijeni rezultati podstiču dalje istraživanje mogućih primena ove toplotne energije koja se može osloboditi ne samo u reakciji destruktivne eksplozije, već i kroy sagorevanje u kontrolisanim uslovima, kao kvaternernu reciklažu otpadnih eksploziva - potencijalni izvor toplotne odnosno električne energije

Quality of explosively welded steel plates using demex explosive

Заваривање експлозивом се често користи када конвенционалне методе заваривања не могу да обезбеде заварени спој два различита материјала, али и када треба заварити неку специфичну геометрију или велике површине металних плоча. Остваривање споја код заваривања експлозивом се заснива на динамичком дејству великог притиска створеног екплозијом. У ту сврху најчешће се користе индустријски експлозиви ниских параметара детонације, а један од њих је DEMEX, произвођача TRAYAL, из Србије. У овом истраживању DEMEX је примењен за заваривање плоча две различите врсте челика. Пре експерименталног поступка заваривања одабраних металних плоча, експлозив добијен од произвођача је подвргнут улазној контроли квалитета: мерењу његове насипне густине и брзине детонације, коришћењем оптичких сонди и фотодетектора повезаног са електронским бројачем. Експериментална поставка за заваривање била је следећа: експлозив DEMEX у прашкастом стању нанесен је у равномерном слоју преко горње челичне плоче, која је хоризонтално постављена преко доње плоче од друге врсте челика, у паралелном положају, са малим дрвеним дистанцерима ивично постављеним између њих. Активација је извршена електродетонирајућом капислом и малим бустером од пластичног експлозива. Заварени спој је испитан применом метода ултразвучне дефектоскопије, течним пенетрантима и микроструктурне анализе завареног споја. Микроструктурне анализе попречног пресека заварених плоча урађене су на стерео и оптичом микроскопу како би се анализирала зона завареног споја.Explosion welding is often used when conventional welding methods cannot provide welded joint of two dissimilar materials, but also when some specific geometry should be welded, or large surfaces of metal plates. The formation of a joint in explosive welding is based on the dynamic effect of the high pressure created by the explosion. For this purpose, most often some industrial explosives of low detonation parameters are used, and one of them is DEMEX, produced by TRAYAL, Serbia. In this research DEMEX was applied to weld plates of two different types of steel. Prior to the experimental procedure of welding, the selected metal plates, the explosive obtained from the producer was subjected to initial quality control: measurement of its bulk density and detonation velocity, using optical probes and a photodetector connected with an electronic counter. The experimental setup for welding was as follows: explosive DEMEX in powdery state was applied in a uniform layer over the upper plate, which was horizontally placed over the lower plate, in parallel position, with small wooden spacers, marginally placed between them. Activation was performed by an electro-detonating cap and a small booster of plastic explosive. The welded joint was examined using methods of ultrasonic defectoscopy, liquid penetrants testing and microstructural analysis of the welded joint. Cross-sectional microstructural analyses of the welded plates were performed using a stereo and optical microscope to analyze the weld zone

Osobine eksplozivno zavarenih ploča aluminijuma i čelika upotrebom Amonex eksploziva

The aim of this study was to investigate the possibility to use the industrial explosive Amonex, which belongs to a group of low-to-middle detonation velocity explosives, for welding of metallic materials. It consists of ammonium nitrate and TNT as energetic components and other inert ingredients and has a powdery consistency, easily applicable in a desirable layer over the metal plates to be welded. Within this research, Amonex was applied to weld plates of aluminium Al 2024 and steel 1.0216 (according to EN 10027-2). The procedure of welding was carried out in the configuration of parallel plates, and afterwards the welded joint was examined. Ultrasonic method and infrared imaging were used as non-destructive techniques, and then the samples were cut from the welded plate using water-jet, in order to perform microscopic analyses of the cross-section in the joint area. It was observed that a good-quality welded joint was obtained, and that the selected explosive may find further application in this area. However, certain nonwelded area was observed, encouraging future modification of the welding procedure set-up.Cilj ove studije je ispitivanje mogućnosti upotrebe industrijskog eksploziva Amonex, koji pripada grupi eksploziva male-do-srednje brzine detonacije, za zavarivanje metalnih materijala. Ovaj eksploziv se sastoji od amonijum nitrata i TNT-a kao energetskih komponenti i drugih inertnih sastojaka, ima praškastu strukturu i lako se nanosi u željenom sloju preko metalnih ploča koje se zavaruju. U okviru ovog istraživanja, Amonex je primenjen na zavarenim pločama aluminijuma Al 2024 i čelika 1.0216 (oznake prema EN 10027-2). Postupak zavarivanja izveden je na paralelno postavljenim pločama, nakon čega je izvršen pregled zavarenog spoja. Kao metode IBR korišćene su ultrazvučna metoda i termovizijsko ispitivanje. Primenom vodenog mlaza iz zavarene ploče su isečeni uzorci u cilju ispitivanja mikrostrukture poprečnog preseka zavarenog spoja. Uočeno je da je dobijen kvalitetan zavareni spoj, te da odabrani eksploziv može naći dalju primenu u ovoj oblasti. Međutim, takođe su uočene i određene površine nezavarenog područja, što je nametnulo potrebu za izmenama postavke ovog postupka zavarivanja

Могућност примене експлозива amonex у заваривању разнородних челичних плоча и утицај количине експлозива на квалитет завареног споја

Детонацијом експлозивних материја ослобађа се велика количина енергије у врло кратком времену, која се примењује за различите врсте корисног рада, како у привредне, тако и у војне сврхе. Поред приме- не експлозивних материја у убојним средствима и за рушење у рударству и грађевинарству, енергија детонације нашла је примену и у заваривању и об- ради метала. Применом енергије настале детонационим разлагањем експло- зива могуће је извршити заваривање метала, обликовање, резање, утицати на повећање његове чврстоће итд. Технологија заваривања експлозивом почела се развијати половином 20. века, и данас је заступљена за израду делова ва- здухоплова, наоружања и војне опреме, оклопних плоча са повећаном бали- стичком заштитом, специјалних цистерни, топлотних измењивача, посуда под притиском,специјалних индустријских резних алата и свих других производа који се не могу израдити неким другим конвенционалним поступком обраде металних материјала. Такође, значајна предност ове технологије је могућност израде вишеслојних материјала великих површина. Заваривање метала експлозијом остварује се као последица веома брзог судара метала под дејством продуката детонације, уз појаву високог притиска и пластичних деформација у облику таласа на граници споја и адијабатског локалног загревања површинских слојева металних материјала. У оквиру овог рада анализирана је могућност примене привредног екс- плозива Amonex у заваривању плоча од опружног челика 51CrV4 и конструк- ционог челика S355 J2. За изабрани експлозив Amonex, који је произведен у Корпорацији ТРАЈАЛ, претходно су измерене насипна густина и брзина дето- нације, где је коришћена метода мерења времена између две тачке у експлозив- ном пуњењу коришћењем електронског бројача са оптичким давачима. Током свих реализованих експеримената коришћена је иста поставка плоча. Коришћене су плоче димензија 150×200 mm. Горња плоча од опружног челика ознаке 51CrV4 дебљине 3 mm, која је убрзавана енергијом експлозије, била је постављена паралелно са непомичном доњом плочом израђеном од кон- струкционог челика ознаке S355 J2 дебљине 10 mm. Почетно одстојање између плоча износило је 4 mm, где су коришћена по 4 ивично постављена одстој- ника израђена од пластичне масе поли(метил метакрилат), скраћено PMMA. Коришћена су експлозивна пуњења три различите масе експлозива Amonex, који је у одговарајућем слоју био равномерно слободно насут на горњу плочу. Таквим експериментима омогућено је одређивање зависности квалитета зава- реног споја од масе примењеног експлозива. За одређивање квалитета завареног споја примењене су две технике ис- питивања без разарања: метода са течним пенетрантима MR68C и испитивање ултразвучним дефектоскопом ознаке Phasor XS. Потом су плоче исечене за даљу анализу, где су извршени микроскопски преглед пресека заварених споје- ва помоћу оптичког микроскопа типа Leitz Metalloplan, опремљеног камером DFC 295 и софтвером за обраду слике LAS 4.3.1. Ударна жилавост споја из- међу експлозијом заварених плоча испитана је на одговарајуће припремљеним епруветама помоћу Шарпијевог клатна ознаке Schenck trebel. Резултати испитивања показали су да експлозив Amonex може наћи примену у експлозивном заваривању, a најбољи резултати постигнути су код узорка завареног средњом количином експлозива. Код овог узорка добијене су највише вредности ударне жилавости на Шарпијевом клатну, док је код трећег завареног споја дошло до наглог пада ударне жилавости услед формирања међуслоја, растопљене фазе на споју, што је потврђено микроскопском ана- лизом. Ултразвучна дефектоскопија је показала да средњи узорак има највећу површину завареног споја, а узорак са најмање експлозива најмању површину завареног споја.Detonation of explosive substances releases a large amount of energy in a very short time, which is used for various types of useful work, both for economic and military purposes. In addition to the use of explosive substances in ordnance and for demolition in mining and construction, detonation energy has found its application in welding and metal processing. By applying the energy generated by the detonation of explosives, it is possible to weld metal, shape it, cut it, increase its solidity, etc. Explosion welding technology began to develop in the middle of the 20th century, and today it is used for the production of aircraft parts, weaponsand military equipment, armour plates with increased ballistic protection, special tanks, heat exchangers, pressure vessels, special industrial cutting tools and all other products which cannot be produced by any other conventional method of processing metal materials. Also, a significant advantage of this technology is the possibility of manufacturing multi-layer materials of large surfaces. The explosion welding of metals is done as a result of the very fast collision of metals under the effect of detonation products, with the appearance of high pressure and plastic deformations in the form of waves at the fusion line and adiabatic local heating of the surface layers of metal materials. In this paper, the possibility of using commercial explosive Amonex for the welding of plates made of 51CrV4 spring steel and S355 J2 structural steel was analysed. For the selected explosive Amonex, which was produced by TRAJAL Corporation, the bulk density and detonation velocity were previously measured, whereby the method of measuring the time between two points in the explosive charge using an electronic counter with optical sensors was used. During all conducted experiments, the same arrangement of plates was used. Plates of dimension 150×200 mm were used. The upper plate of 3 mm thick 51CrV4 spring steel, which was accelerated by the energy of the explosion, was placed parallel to a stationary lower plate made of 10 mm thick S355 J2 structural steel. The initial distance between the plates was 4 mm, where 4 edge spacers made of plastic mass poly(methyl methacrylate), abbreviated PMMA, were used. Explosive charges of three different masses of Amonex explosive were used, which was evenly and freely poured in the appropriate layer on the upper plate. Such experiments made it possible to determine the dependence of the quality of the welded joint on the mass of the explosive used. To determine the quality of the welded joint, two non-destructive testing techniques were applied: the method with liquid penetrants MR68C and testing with an ultrasonic defectoscope Phasor XS. Then the plates were cut for further analysis, whereby the microscopic examination of the sections of the welded joints was performed using the Leitz Metalloplan optical microscope equipped with a DFC 295 camera and LAS 4.3.1 image processing software. The impact toughness of the joint between the explosion-welded plates was tested on appropriately prepared test tubes using the Charpy pendulum Schenck trebel. The test results showed that Amonex explosive can be used in explosion welding, and the best results were achieved with a sample welded with a medium amount of explosive. In this sample, the highest values of impact toughness were obtained on the Charpy pendulum, while in the third welded joint there was a sudden decrease in impact toughness due to the formation of an intermediate layer, a molten phase at the joint, which was confirmed by microscopic analysis. Ultrasonic defectoscopy showed that the middle sample had the largest area of the welded joint, and the sample with the least explosive had the smallest area of the welded joint

Testing the quality of explosively welded joints of dissimilar metals potentially applicable in renewable energy sources

Explosively welded metal plates of large surfaces or specific geometries are used in equipment for the production of electricity from renewable sources. In explosive welding, the energy of a controlled detonation is used to create a joint, when one metal part collides with another at high speed forming a weavy bonded interface. Explosive welding is used in the production of specialized components for renewable energy sources, such as parts of wind farms or turbines, because enables strong and secure connections between different types of metal or material. This technique can also be applied in the production of specific components for solar industry, such as solar panel supports that require strong and reliable connections, often between dissimilar materials that are difficult to weld with conventional methods. In addition, explosive welding can be useful in the production of batteries for renewable energy storage, where it is crucial to ensure that the connections are mechanical and electrically reliable. For such structures it is important to be able to perform in situ monitoring using nondestructive techniques to check the success of the performed welding on the whole pieces or products made this way. This work considers the application of non-destructive and destructive techniques to examine the quality of explosively welded joints of two different sets of metal plates: aluminum alloy-steel and carbon steel- highly wear resistant alloy steel, with two explosives, Amonex and Demex. Inspection of the joints was carried out using surface methods and non-destructive volumetric methods. The following techniques were applied: visual method, liquid penetrant testing, X-ray and ultrasound defectoscopy. To confirm the results of non-destructive techniques, a microstructural analysis of the cross-section of the welded joint was performed. The application of non-destructive testing techniques in testing the quality of explosively welded joints contributes to the reduction of costs that would be caused by destructive tests, since these techniques can be used to monitor the success of the process itself and thus improve the technological process of producing bimetallic joints by explosive welding.Eksplozivno zavarene metalne ploče velikih površina ili specifične geometrije nalaze primenu u opremi za proizvodnju električne energije iz obnovljivih izvora. U eksplozivnom zavarivanju koristi se energija kontrolisane detonacije da bi se ostvario spoj, kada se jedan metalni deo sudara sa drugim velikom brzinom formirajući spoj talasastog profila. Eksplozivno zavarivanje se koristi u proizvodnji specijalnih komponenti za obnovljive izvore energije, kao što su delovi vetroelektrana ili turbina, jer omogućava čvrste i sigurne spojeve između različitih vrsta metala. Ova tehnika se može primeniti i u izradi specifičnih komponenti za solarnu industriju, kao što su nosači solarnih panela koji zahtevaju snažne i pouzdane veze, neretko između raznorodnih materijala koje je teško zavariti konvencionalnim postupcima. Osim toga, eksplozivno zavarivanje može biti korisno u proizvodnji baterija za skladištenje obnovljive energije, gde je ključno osigurati da su spojevi mehanički i električki pouzdani. Za primenu u takvim konstrukcijama važno je da se može vršiti in situ kontrola primenom nedestruktivnih tehnika kako bi se proverila uspešnost izvršenog zavarivanja celih komada ili proizvoda dobijenih na ovaj način. U ovom radu prikazana je primena nedestruktivnih i destruktivnih tehnika za ispitivanje kvaliteta eksplozivno zavarenih spojeva dva različita seta metalnih ploča: aluminijumska legura-čelik i ugljenični čelik-alatni čelik, sa dva eksploziva, Amonex i Demex. Ispitivanje kvaliteta ostvarenih spojeva vršeno je površinskim metodama i zapreminskim metodama bez razaranja i sa razaranjem. Primenjene su sledeće tehnike bez razaranja: vizuelna metoda, ispitivanje tečnim penetrantima, radiografija i ultrazvučno ispitivanje. Kako bi se rezultati nedestruktivnih tehnika potvrdili, izvšena je i mikrostrukturna analiza poprečnog preseka zavarenog spoja. Primena tehnika ispitivanja bez razaranja u ispitivanju kvaliteta eksplozivno zavarenih spojeva doprinosi smanjenju troškova kada se vrše destruktivna ispitivanja. Ovim tehnikama može pratiti uspešnost samog procesa i na taj način poboljšati tehnološki proces izrade bimetalnih spojeva eksplozivnim zavarivanjem.Plenarno predavanje / Plenary lecture - A. Ali