mateja snajdar - Academia.edu (original) (raw)
Papers by mateja snajdar
Zbornik sažetaka Međunarodnog savjetovanja MATRIB 2010 održanog u Veloj Luci od 23. do 25.06.2010.
Tijekom pola stoljeća intenzivnog korištenja polimera uočena je kod nekih osjetljivost na djelova... more Tijekom pola stoljeća intenzivnog korištenja polimera uočena je kod nekih osjetljivost na djelovanje vode. Ona je posebice izražena kod poliamida 6. Djelovanje vode na ovu vrstu polimera uzrokuje promjene u njegovoj strukturi, svojstvima, a time i ponašanju tijekom eksploatacije. Upravo je zato važno utvrditi u kojoj mjeri voda utječe na njegova svojstva, kako se ona tijekom primjene u okolini koja sadrži vlagu ili vodu ne bi narušila do te mjere da poliamidni dio nije sposoban obavljati svoju funkciju. U ovom radu nastoji se ustanoviti kakvo je djelovanje vode na PA 6, o kojim utjecajnim faktorima ovisi i kako se odražava na njegova svojstva. Eksperimentalni dio obuhvaća ispitivanje djelovanja vode na poliamid 6. Detaljno je opisan princip određivanja apsorbirane i desorbirane vode tijekom tretiranja u razdoblju od 28 dana. U prvom djelu ispitivanja pratila se promjena mase 10 epruveta poliamida 6 uronjenih u vodu i drugih 10 epruveta podvrgnutih sušenju u eksikatoru. Na taj način ...
Composites Part B: Engineering, 2016
Abstract Aluminium foams are lightweight porous materials with wide range of possible application... more Abstract Aluminium foams are lightweight porous materials with wide range of possible applications. In order to use them as a widespread construction material still many of their properties need to be fully investigated. Nanoindentation of closed cell aluminium foams was conducted in order to investigate cell wall mechanical properties. During this study AlMgSi0.6 foams with different cooling regimes after foaming and different subsequent heat treatments were tested in order to obtain insight into influence of mentioned parameters on cell wall properties such micro-hardness. Nanoindentation is a technique similar to the conventional hardness testing but preformed on a nano-scale level which makes it adequate technique for investigating thin films and layers but also thin walls of cellular materials such as metal foams. Aluminium alloy foam rod shaped samples were produced by means of powder compacts foaming method but with different subsequent heat treatment; some were air cooled and some were cooled in water. After cooling from foaming temperature some of the samples were subsequently heat treated while others were not which resulted in four types of samples. The highest values of hardness were detected for fully heat treated samples.
Materials Testing, 2012
Apart from erosion of leading edges, erosion of the rotor blades trailing edges often occurs in c... more Apart from erosion of leading edges, erosion of the rotor blades trailing edges often occurs in condensing steam turbines, due to the impact of wet steam water droplets. Considerable erosion of the rotor blades trailing edges may be more dangerous for a reliable turbine operation than the leading edges erosion. During several years of research many results concerning erosion damage to the trailing edges of 66 MW condensing reduction steam turbine final stage rotor blades at the Thermo-electric power plant – heating plant (TE-TO) Zagreb have been gathered and are presented in this paper. Correlation between the erosion process behavior of the last stage turbine rotor blades trailing edges and the number of operating hours has been established.
Processing and Application of Ceramics, 2013
Aluminium based metal matrix composites are rapidly developing group of materials due to their un... more Aluminium based metal matrix composites are rapidly developing group of materials due to their unique combination of properties that include low weight, elevated strength, improved wear and corrosion resistance and relatively good ductility. This combination of properties is a result of mixing two groups of materials with rather different properties with aluminium as ductile matrix and different oxides and carbides added as reinforcement. Al2O3, SiC and ZrO2 are the most popular choices of reinforcement material. One of the most common methods for producing this type of metal matrix composites is powder metallurgy since it has many variations and also is relatively low-cost method. Many different techniques of compacting aluminium and ceramic powders have been previously investigated. Among those techniques equal channel angular pressing (ECAP) stands out due to its beneficial influence on the main problem that arises during powder compaction and that is a non-uniform distribution o...
The Minerals, Metals & Materials Series, 2017
Key Engineering Materials, 2016
Powder metallurgy (PM) commercial purity titanium (CP Ti) was fabricated and studied, with an aim... more Powder metallurgy (PM) commercial purity titanium (CP Ti) was fabricated and studied, with an aim of utilization for dental application. PM CP Ti was manufactured using a cost effective approach, where affordable hydrogenation–dehydrogenation (HDH) process Ti 99.4 wt.% powder was consolidated via the following sequence of PM techniques: cold isostatic pressing, warm vacuum pressing at 420 °C and warm direct extrusion at 500 °C. The paper presents the first studies on processing, microstructure, testing of mechanical properties, fatigue performance and bonding strength with different veneer coatings. By employed consolidation process sound material with low porosity (1.5%) and sustained oxygen content (0.21 wt.%) was attained. The tensile properties obtained for PM CP Ti (UTS = 701 MPa, YS0.2 = 512 MPa, ε = 13 %) were improved over to those for cast / milled CP Ti Grade 4 reference, the material commonly used in dentistry. Tested using the ISO 14801 standard for dental implants, the ...
Strojarstvo Casopis Za Teoriju I Praksu U Strojarstvu, Aug 31, 2011
Original scientific paper One of the main disadvantages of composite materials like glass or carb... more Original scientific paper One of the main disadvantages of composite materials like glass or carbon fiber reinforced composites in use today is their inability to be recycled. After the end of a product or part life cycle, there is no way to separate the fibers from the matrix, or to recycle them except for deposition or shredding. Biopolymer based composites have an increasing and bright future due to their recyclability, reproduction capability, available sources and economic factors without the fundamental loss of mechanical properties. This paper deals with natural-bamboo fiber reinforced composite material design and its basic mechanical properties testing. Izrada polimernog kompozita ojačanog prirodnim vlaknima Izvornoznanstveni članak Jedan od velikih nedostataka sadašnjih kompozitnih materijala poput kompozita sa staklenim ili ugljičnim vlaknima jest nemogućnost njihova recikliranja. Nakon isteka vijeka trajanja proizvoda ili dijela, iz kompozitnih materijala trenutno nije moguće razdvojiti vlakna i matricu, niti ih reciklirati drugim metodama osim deponiranjem ili usitnjavanjem za agregat pri polaganju cesta. Bio-polimerni kompoziti imaju sve veću primjenu i svijetlu budućnost upravo iz razloga recikličnosti, lake obnovljivosti, dostupnih izvora i ekonomičnosti, bez znatnih gubitaka mehaničkih svojstava. U ovom radu pokazana je izrada kompozitnog materijala, poliesterske matrice, ojačanog prirodnim, bambusovim vlaknima, te ispitivanje osnovnih mehaničkih svojstava ispitnog uzorka.
Strojarstvo Casopis Za Teoriju I Praksu U Strojarstvu, Aug 31, 2011
Original scientific paper One of the main disadvantages of composite materials like glass or carb... more Original scientific paper One of the main disadvantages of composite materials like glass or carbon fiber reinforced composites in use today is their inability to be recycled. After the end of a product or part life cycle, there is no way to separate the fibers from the matrix, or to recycle them except for deposition or shredding. Biopolymer based composites have an increasing and bright future due to their recyclability, reproduction capability, available sources and economic factors without the fundamental loss of mechanical properties. This paper deals with natural-bamboo fiber reinforced composite material design and its basic mechanical properties testing. Izrada polimernog kompozita ojačanog prirodnim vlaknima Izvornoznanstveni članak Jedan od velikih nedostataka sadašnjih kompozitnih materijala poput kompozita sa staklenim ili ugljičnim vlaknima jest nemogućnost njihova recikliranja. Nakon isteka vijeka trajanja proizvoda ili dijela, iz kompozitnih materijala trenutno nije moguće razdvojiti vlakna i matricu, niti ih reciklirati drugim metodama osim deponiranjem ili usitnjavanjem za agregat pri polaganju cesta. Bio-polimerni kompoziti imaju sve veću primjenu i svijetlu budućnost upravo iz razloga recikličnosti, lake obnovljivosti, dostupnih izvora i ekonomičnosti, bez znatnih gubitaka mehaničkih svojstava. U ovom radu pokazana je izrada kompozitnog materijala, poliesterske matrice, ojačanog prirodnim, bambusovim vlaknima, te ispitivanje osnovnih mehaničkih svojstava ispitnog uzorka.
Aluminium foams are lightweight porous materials with wide range of possible applications. In ord... more Aluminium foams are lightweight porous materials with wide range of possible applications. In order to use them as a widespread construction material still many of their properties need to be fully investigated. Nanoindentation of closed cell aluminium foams was conducted in order to investigate cell wall mechanical properties. During this study AlMgSi0.6 foams with different cooling regimes after foaming and different subsequent heat treatments were tested in order to obtain insight into influence of mentioned parameters on cell wall properties such micro-hardness. Nanoindentation is a technique similar to the conventional hardness testing but preformed on a nano-scale level which makes it adequate technique for investigating thin films and layers but also thin walls of cellular materials such as metal foams. Aluminium alloy foam rod shaped samples were produced by means of powder compacts foaming method but with different subsequent heat treatment; some were air cooled and some were cooled in water. After cooling from foaming temperature some of the samples were subsequently heat treated while others were not which resulted in four types of samples. The highest values of hardness were detected for fully heat treated samples.
Zbornik sažetaka Međunarodnog savjetovanja MATRIB 2010 održanog u Veloj Luci od 23. do 25.06.2010.
Tijekom pola stoljeća intenzivnog korištenja polimera uočena je kod nekih osjetljivost na djelova... more Tijekom pola stoljeća intenzivnog korištenja polimera uočena je kod nekih osjetljivost na djelovanje vode. Ona je posebice izražena kod poliamida 6. Djelovanje vode na ovu vrstu polimera uzrokuje promjene u njegovoj strukturi, svojstvima, a time i ponašanju tijekom eksploatacije. Upravo je zato važno utvrditi u kojoj mjeri voda utječe na njegova svojstva, kako se ona tijekom primjene u okolini koja sadrži vlagu ili vodu ne bi narušila do te mjere da poliamidni dio nije sposoban obavljati svoju funkciju. U ovom radu nastoji se ustanoviti kakvo je djelovanje vode na PA 6, o kojim utjecajnim faktorima ovisi i kako se odražava na njegova svojstva. Eksperimentalni dio obuhvaća ispitivanje djelovanja vode na poliamid 6. Detaljno je opisan princip određivanja apsorbirane i desorbirane vode tijekom tretiranja u razdoblju od 28 dana. U prvom djelu ispitivanja pratila se promjena mase 10 epruveta poliamida 6 uronjenih u vodu i drugih 10 epruveta podvrgnutih sušenju u eksikatoru. Na taj način ...
Composites Part B: Engineering, 2016
Abstract Aluminium foams are lightweight porous materials with wide range of possible application... more Abstract Aluminium foams are lightweight porous materials with wide range of possible applications. In order to use them as a widespread construction material still many of their properties need to be fully investigated. Nanoindentation of closed cell aluminium foams was conducted in order to investigate cell wall mechanical properties. During this study AlMgSi0.6 foams with different cooling regimes after foaming and different subsequent heat treatments were tested in order to obtain insight into influence of mentioned parameters on cell wall properties such micro-hardness. Nanoindentation is a technique similar to the conventional hardness testing but preformed on a nano-scale level which makes it adequate technique for investigating thin films and layers but also thin walls of cellular materials such as metal foams. Aluminium alloy foam rod shaped samples were produced by means of powder compacts foaming method but with different subsequent heat treatment; some were air cooled and some were cooled in water. After cooling from foaming temperature some of the samples were subsequently heat treated while others were not which resulted in four types of samples. The highest values of hardness were detected for fully heat treated samples.
Materials Testing, 2012
Apart from erosion of leading edges, erosion of the rotor blades trailing edges often occurs in c... more Apart from erosion of leading edges, erosion of the rotor blades trailing edges often occurs in condensing steam turbines, due to the impact of wet steam water droplets. Considerable erosion of the rotor blades trailing edges may be more dangerous for a reliable turbine operation than the leading edges erosion. During several years of research many results concerning erosion damage to the trailing edges of 66 MW condensing reduction steam turbine final stage rotor blades at the Thermo-electric power plant – heating plant (TE-TO) Zagreb have been gathered and are presented in this paper. Correlation between the erosion process behavior of the last stage turbine rotor blades trailing edges and the number of operating hours has been established.
Processing and Application of Ceramics, 2013
Aluminium based metal matrix composites are rapidly developing group of materials due to their un... more Aluminium based metal matrix composites are rapidly developing group of materials due to their unique combination of properties that include low weight, elevated strength, improved wear and corrosion resistance and relatively good ductility. This combination of properties is a result of mixing two groups of materials with rather different properties with aluminium as ductile matrix and different oxides and carbides added as reinforcement. Al2O3, SiC and ZrO2 are the most popular choices of reinforcement material. One of the most common methods for producing this type of metal matrix composites is powder metallurgy since it has many variations and also is relatively low-cost method. Many different techniques of compacting aluminium and ceramic powders have been previously investigated. Among those techniques equal channel angular pressing (ECAP) stands out due to its beneficial influence on the main problem that arises during powder compaction and that is a non-uniform distribution o...
The Minerals, Metals & Materials Series, 2017
Key Engineering Materials, 2016
Powder metallurgy (PM) commercial purity titanium (CP Ti) was fabricated and studied, with an aim... more Powder metallurgy (PM) commercial purity titanium (CP Ti) was fabricated and studied, with an aim of utilization for dental application. PM CP Ti was manufactured using a cost effective approach, where affordable hydrogenation–dehydrogenation (HDH) process Ti 99.4 wt.% powder was consolidated via the following sequence of PM techniques: cold isostatic pressing, warm vacuum pressing at 420 °C and warm direct extrusion at 500 °C. The paper presents the first studies on processing, microstructure, testing of mechanical properties, fatigue performance and bonding strength with different veneer coatings. By employed consolidation process sound material with low porosity (1.5%) and sustained oxygen content (0.21 wt.%) was attained. The tensile properties obtained for PM CP Ti (UTS = 701 MPa, YS0.2 = 512 MPa, ε = 13 %) were improved over to those for cast / milled CP Ti Grade 4 reference, the material commonly used in dentistry. Tested using the ISO 14801 standard for dental implants, the ...
Strojarstvo Casopis Za Teoriju I Praksu U Strojarstvu, Aug 31, 2011
Original scientific paper One of the main disadvantages of composite materials like glass or carb... more Original scientific paper One of the main disadvantages of composite materials like glass or carbon fiber reinforced composites in use today is their inability to be recycled. After the end of a product or part life cycle, there is no way to separate the fibers from the matrix, or to recycle them except for deposition or shredding. Biopolymer based composites have an increasing and bright future due to their recyclability, reproduction capability, available sources and economic factors without the fundamental loss of mechanical properties. This paper deals with natural-bamboo fiber reinforced composite material design and its basic mechanical properties testing. Izrada polimernog kompozita ojačanog prirodnim vlaknima Izvornoznanstveni članak Jedan od velikih nedostataka sadašnjih kompozitnih materijala poput kompozita sa staklenim ili ugljičnim vlaknima jest nemogućnost njihova recikliranja. Nakon isteka vijeka trajanja proizvoda ili dijela, iz kompozitnih materijala trenutno nije moguće razdvojiti vlakna i matricu, niti ih reciklirati drugim metodama osim deponiranjem ili usitnjavanjem za agregat pri polaganju cesta. Bio-polimerni kompoziti imaju sve veću primjenu i svijetlu budućnost upravo iz razloga recikličnosti, lake obnovljivosti, dostupnih izvora i ekonomičnosti, bez znatnih gubitaka mehaničkih svojstava. U ovom radu pokazana je izrada kompozitnog materijala, poliesterske matrice, ojačanog prirodnim, bambusovim vlaknima, te ispitivanje osnovnih mehaničkih svojstava ispitnog uzorka.
Strojarstvo Casopis Za Teoriju I Praksu U Strojarstvu, Aug 31, 2011
Original scientific paper One of the main disadvantages of composite materials like glass or carb... more Original scientific paper One of the main disadvantages of composite materials like glass or carbon fiber reinforced composites in use today is their inability to be recycled. After the end of a product or part life cycle, there is no way to separate the fibers from the matrix, or to recycle them except for deposition or shredding. Biopolymer based composites have an increasing and bright future due to their recyclability, reproduction capability, available sources and economic factors without the fundamental loss of mechanical properties. This paper deals with natural-bamboo fiber reinforced composite material design and its basic mechanical properties testing. Izrada polimernog kompozita ojačanog prirodnim vlaknima Izvornoznanstveni članak Jedan od velikih nedostataka sadašnjih kompozitnih materijala poput kompozita sa staklenim ili ugljičnim vlaknima jest nemogućnost njihova recikliranja. Nakon isteka vijeka trajanja proizvoda ili dijela, iz kompozitnih materijala trenutno nije moguće razdvojiti vlakna i matricu, niti ih reciklirati drugim metodama osim deponiranjem ili usitnjavanjem za agregat pri polaganju cesta. Bio-polimerni kompoziti imaju sve veću primjenu i svijetlu budućnost upravo iz razloga recikličnosti, lake obnovljivosti, dostupnih izvora i ekonomičnosti, bez znatnih gubitaka mehaničkih svojstava. U ovom radu pokazana je izrada kompozitnog materijala, poliesterske matrice, ojačanog prirodnim, bambusovim vlaknima, te ispitivanje osnovnih mehaničkih svojstava ispitnog uzorka.
Aluminium foams are lightweight porous materials with wide range of possible applications. In ord... more Aluminium foams are lightweight porous materials with wide range of possible applications. In order to use them as a widespread construction material still many of their properties need to be fully investigated. Nanoindentation of closed cell aluminium foams was conducted in order to investigate cell wall mechanical properties. During this study AlMgSi0.6 foams with different cooling regimes after foaming and different subsequent heat treatments were tested in order to obtain insight into influence of mentioned parameters on cell wall properties such micro-hardness. Nanoindentation is a technique similar to the conventional hardness testing but preformed on a nano-scale level which makes it adequate technique for investigating thin films and layers but also thin walls of cellular materials such as metal foams. Aluminium alloy foam rod shaped samples were produced by means of powder compacts foaming method but with different subsequent heat treatment; some were air cooled and some were cooled in water. After cooling from foaming temperature some of the samples were subsequently heat treated while others were not which resulted in four types of samples. The highest values of hardness were detected for fully heat treated samples.