In order to develop the application of the more cost-effective copper-based shape memory alloys (... more In order to develop the application of the more cost-effective copper-based shape memory alloys (SMAs), rather than nickel–titanium as earthquake energy dissipaters, the influence of ausforming-induced plastic deformation on phase transformations, microstructure, super elasticity and mechanical properties of the shape memory alloy Cu-26Zn-4Al was examined. These specific SMA properties were targeted by applying appropriate parameters of the thermomechanical (the so-called ausforming) process: beta-phase homogenization at 800 °C for 20 min, one-step hot rolling at 800 °C and water quenching. The results showed significant microstructural changes, increased mechanical resistance and change in the phase transformation behavior. The SMA treated by ausforming retained the reversible austenitic–martensitic transformation ability, with the appearance of the super-elastic effect up to 6% of strain recovery. Although some strengthening occurred after hot rolling (an increase in true yield st...
The fuzzy logic controller, which uses an analytic activation function for the defuzzification pr... more The fuzzy logic controller, which uses an analytic activation function for the defuzzification procedure, was applied to the position control of a servo pneumatic drive controlled by a proportional valve. The Gaussian shape of input fuzzy sets, with the possibility of their modification, was used to fuzzify the input signal. The control signal was determined by introducing an analytic function instead of defining the fuzzy rule base. In this way, a conventional 2-D fuzzy rule table base is modified into 1-D fuzzy defuzzification based on an analytic function to calculate the controller output. In this control algorithm, the problem of conventional fuzzy logic control, in terms of the exponential growth in rules as the number of input variables increases, is eliminated. The synthesis controller procedure is adjusted to the flow rate characteristic of the proportional valve. The developed control algorithms are verified by computer simulation and by testing on a real pneumatic rodless...
Hot rolling of CuZn27Al4 shape memory alloy results in the forming of defects in austenitic cryst... more Hot rolling of CuZn27Al4 shape memory alloy results in the forming of defects in austenitic crystals. The defects such as dislocation and deformed boundaries of austenitic grains affect both “ classical” material properties and the specific properties related to shape memory. Rolled and quenched alloy (ausforming treatment) shows hardening proportional to the value of introduced deformation. By increasing the level of true plastic deformation not only the yield stress and tensile strength are increased but also the pseudo yield stress thus making the mechanically induced martensitic transformation more difficult. Besides, the ausforming treatment reduces all the transformation temperatures of the austenitic-martensitic reaction, thus expanding the temperature field of pseudo-elasticity. In spite of the hardening, the thermo-mechanically treated CuZn27Al4 alloy retains the pseudo-elastic shape memory so that favourable combination of strength and transformation behaviour can be achie...
In this paper the hardness and fracture toughness values for nanostructured cemented carbides wer... more In this paper the hardness and fracture toughness values for nanostructured cemented carbides were tested and analyzed. The experimental part included the testing of three samples: WC with 5% cobalt (WC-5Co), WC with 10% cobalt (WC-10Co) and WC with 15% cobalt (WC-15Co). Hardness was tested by Vickers method (HV30) according to HR EN ISO 6507-1: 2005, and fracture toughness was determined by the Palmqvist method according to ISO 28079: 2009. Palmqvist's method uses the length of cracks that propagate from the tip of the Vickers pyramid imprint to determine fracture toughness. The results show that by increasing the amount of cobalt in cemented carbides hardness values drop, and the fracture toughness increases. They also indicate that using nanostructured cemented carbides increases hardness with a slight change in toughness.
Preload plays an important role in the calibration procedure of a testing machine and represents ... more Preload plays an important role in the calibration procedure of a testing machine and represents an inevitable part of the calibration process. Preload affects the calibration results in the form of relative errors of the measuring system of force which is indirectly reflected also on the class of the measuring range. By performing one or several preloading there is a significant change in the values of characteristic relative errors: accuracy, repeatability and reversibility which represent the classification criteria in determining the class. A greater number of preloads makes worse the error of accuracy whereas the error of repeatability and in particular the error of reversibility are reduced in the absolute amount. Furthermore, preload affects also the residual force which remains on the standard measurement instrument after removing load. Already one preload minimizes this residue and thus allows valid testing. Therefore, the preload in checking the testing machine represents ...
Pojava povecane buke i vibracija elektromotora klipnog kompresora ukazala je na postojanje pukoti... more Pojava povecane buke i vibracija elektromotora klipnog kompresora ukazala je na postojanje pukotine na pogonskom kraju vratila. Provedeno je vise nerazornih ispitivanja kao sto su magnetska kontrola (MT), penetrantska kontrola (UT) i ultrazvucna kontrola (UT) kojima se detektirala pukotina pod kutem od 45o ; ; s obzirom na uzdužnu os vratila. Materijal vratila analiziran je na temelju mehanickih svojstava i mikrostrukture. Rezultati ispitivanja pokazali su da na vratilu nije provedena toplinska obrada poboljsavanja vec se radi o normaliziranom celiku s heterogenom feritno-perlitno mikrostrukturom. Takva heterogena mikrostruktra sacinjena od mekse i tvrđe faze nepovoljno utjece na dinamicki opterecene dijelove jer pogoduje pojavi umora materijala. Nadalje, skoro nikakvo zaobljenje u korijenu upustenog dijela za sjediste glave vijka odnosno matice na prirubnici vratila uzrokovalo je koncentraciju naprezanja na mjestu upustenja cime je također smanjena otpornost vratila na pojavu umora...
Original scientific paper Hot rolling of CuZn27Al4 shape memory alloy results in the forming of d... more Original scientific paper Hot rolling of CuZn27Al4 shape memory alloy results in the forming of defects in austenitic crystals. The defects such as dislocation and deformed boundaries of austenitic grains affect both "classical" material properties and the specific properties related to shape memory. Rolled and quenched alloy (ausforming treatment) shows hardening proportional to the value of introduced deformation. By increasing the level of true plastic deformation not only the yield stress and tensile strength are increased but also the pseudo yield stress thus making the mechanically induced martensitic transformation more difficult. Besides, the ausforming treatment reduces all the transformation temperatures of the austenitic-martensitic reaction, thus expanding the temperature field of pseudo-elasticity. In spite of the hardening, the thermo-mechanically treated CuZn27Al4 alloy retains the pseudo-elastic shape memory so that favourable combination of strength and tr...
U radu je istraživan utjecaj parametara rastopnog žarenja na svojstva aluminijske legure. Analizi... more U radu je istraživan utjecaj parametara rastopnog žarenja na svojstva aluminijske legure. Analiziran je utjecaj temperature i trajanja rastopnog žarenja na mikrostrukturu i mehanicka svojstva lijevane AlSiMgMn legure. Uzorci su rastopno žareni na 520°C i 560°C u trajanju 1, 5 i 3 sata. Parametri umjetnog dozrijevanja bili su jednaki za sve uzorke. Na svjetlosnom mikroskopu provedena je kvalitativna i kvantitativna analiza mikrostrukture toplinski obrađenih uzoraka te lijevanog stanja. Na svim uzorcima izmjerena je mikrotvrdoca (HV0, 05 i HV0, 1) i provedeno staticko vlacno ispitivanje kako bi se odredila optimalna temperatura i vrijeme rastopnog žarenja u postupku precipitacijskog ocvrsnuca.
Toplim valjanjem razlicitim iznosima stvarne deformacije (0-1,54mm/mm), provedenim na temperaturi... more Toplim valjanjem razlicitim iznosima stvarne deformacije (0-1,54mm/mm), provedenim na temperaturi između 650C i 800C (ausforming obradba, AF), uvode se defekti u CuZn27Al4-Slitinu. Ovi defekti i mikrostrukturne promjene analizirani su kombinacijom svetlosne i elektronske mikroskopije. Mehanicka svojstva slitine određene su mjerenjem tvrdoce i vlacnim ispitivanjem. Uobicajene metode mjerenja tvrdoce nisu prikladne kod slitina s efektom prisjetljivosti oblika, izuzev mjerenja tvrdoce nisu prikladne kod slitina s efektom prisjetljivosti oblika, izuzev mjerenja s malim opterecenjem, i to stabilnog autenita pri temperaturi > AF. Kod mjerenja tvrdoce vecim opterecenjima pojavljuju se anomalije koje vode do odstupanja izmjerene i stvarne tvrdoce, te je prisutna pojava pseudotvrdoce. Nakon toplog valjanja u podrucju visih temperatura (AF>700C) i izravnog gasenja u vodi javlja se znatno ocvrscenje slitine, dok istom obradbom u podrucju nižih temperatura (AF < 700C) ne dolazi do ocvr...
U radu je istraživan utjecaj parametara rastopnog žarenja na svojstva aluminijske legure. Analizi... more U radu je istraživan utjecaj parametara rastopnog žarenja na svojstva aluminijske legure. Analiziran je utjecaj temperature i trajanja rastopnog žarenja na mikrostrukturu i mehanicka svojstva lijevane AlSiMgMn legure. Uzorci su rastopno žareni na 520°C i 560°C u trajanju 1, 5 i 3 sata. Parametri umjetnog dozrijevanja bili su jednaki za sve uzorke. Na svjetlosnom mikroskopu provedena je kvalitativna i kvantitativna analiza mikrostrukture toplinski obrađenih uzoraka te lijevanog stanja. Na svim uzorcima izmjerena je mikrotvrdoca (HV0, 05 i HV0, 1) i provedeno staticko vlacno ispitivanje kako bi se odredila optimalna temperatura i vrijeme rastopnog žarenja u postupku precipitacijskog ocvrsnuca.
Lomom siljaka ionizacijske elektrode bitno su narusena funkcionalna svojstva elektrode i znacajno... more Lomom siljaka ionizacijske elektrode bitno su narusena funkcionalna svojstva elektrode i znacajno smanjena ucinkovitost elektrofiltera. Pojava loma, u kratkom vremenskom periodu, dovodi se u vezu s vodikovom krhkosti potpomognutom dinamickim opterecenjem tijekom potresanja elektrode. Ovaj oblik napetosne korozije nastupa na vlacnom napregnutim mjestima pod djelovanjem agresivnog medija. Naime, za vrijeme rada postrojenja, a posebice tijekom njegova zastoja zbivaju se kemijske reakcije kojima nastaje otopina sumporne kiseline (H2SO4). Reakcijom agresivne kiseline i željeza oslobađa se atomarni vodik koji difundira u kristalnu resetku željeza i time uzrokuje izvitoperenje resetke. Inducirana naprezanja superponiraju se s postojecim naprezanjima, tj. naprezanjima u radu, zaostalim naprezanjima toplinskog porijekla (zavarivacke napetosti) i naprezanjima uslijed hladne deformacije. Kada ukupno naprezanje dostigne vrijednost vlacne cvrstoce dolazi do loma.
The research results of the study conducted show the effect of the change in the voltage of the d... more The research results of the study conducted show the effect of the change in the voltage of the developing drum and the voltage of the squeegee roller, which in fact are the first and last part of the development process and this is subsequently one of the phases of indirect electrophotographic printing on the recycling mechanism and characteristics of recycled fibers. The substrates bases are woodfree uncoated paper and coated paper intended for LEP printing technology, with the purpose of achieving high quality double-sided printing. The results confirm a decrease in the specks count and a larger speck area on a handsheet prior to flotation, when increasing the negative voltage of the developing drum. The specks count is higher on the handsheet obtained by recycling prints on uncoated paper versus coated paper. A greater speck count is removed by the flotation of prints on uncoated paper (approximately 73%), unlike coated paper (approximately 28%). When dealing with non-deinked ha...
In this study, aluminum foams reinforced with different steel elements were produced by the AluLi... more In this study, aluminum foams reinforced with different steel elements were produced by the AluLight process. The master alloy AlMgSi0.6 was used as the matrix material, titanium hydride (TiH2) powder was used as a foaming agent, and steel wire, cylindrical steel mesh and flat steel mesh were used as reinforcing elements. Reinforcements were placed inside the mold, along with the precursors, and samples were manufactured by gas releasing particles in a semi-solid state. To examine the effect of the reinforcements on specific energy absorption, quasi-static uniaxial compression tests were carried out, with a constant separation rate of 1 mm/s. From the tested results, the energy absorption per unit volume and specific energy absorption efficiency were calculated and then also statistically evaluated. The results showed that examined shapes of reinforcements affect differently specific energy absorption and its efficiency, compared to non-reinforced aluminum foams. The best result obt...
Journal of Materials Research and Technology, 2021
Abstract The generated process losses such as broken ware from shaping, if not recycled internall... more Abstract The generated process losses such as broken ware from shaping, if not recycled internally, are considered as waste. Furthermore, the collected process losses are provided to external recycling companies or waste disposal facilities. This study investigated the recycling potential of waste alumina powder, which was accumulated during industrial machining of the ceramic green body. The samples containing up to 20 dwb. % (dwb – weight amounts based on dry matter) of powdered waste alumina were prepared by slip casting method and conventionally sintered at various sintering conditions according to Box-Behnken design. Sintered samples were characterized for density, microstructure, hardness, and indentation fracture toughness and compared with samples made of pure commercial alumina. The study shows that the addition of waste alumina up to 20 dwb. % sintered at higher sintering temperature with dwell time 1–3 h did not negatively affect the hardness, nor the indentation fracture toughness of the sintered samples. The enabled recycling potential of waste alumina powder can have direct positive environmental impact, although economic benefits cannot be ignored.
Samples of nanostructured hardmetals were sintered as a substrate material by applying two differ... more Samples of nanostructured hardmetals were sintered as a substrate material by applying two different powder metallurgy processes. The starting powders had an average grain size from 95 nm to 150 nm. The plasma-assisted chemical vapour deposition technique was used for the deposition of coatings and two coating systems, i.e. the 2 µm titanium nitride and 3.8 µm titanium carbon nitride were produced. Scratch tests were conducted with an increasing load ranging from 5 to 200 N. Critical normal loads of coating delamination during the scratch tests were registered. The sliding wear resistance was investigated with a ball-on-disc test. The ball-on-disc test showed that the porosity of the sintered product had the highest impact on the wear volume loss. Nanostructured hardmetals showed a great potential for application of plasma-assisted chemical Vapour deposition.
In order to develop the application of the more cost-effective copper-based shape memory alloys (... more In order to develop the application of the more cost-effective copper-based shape memory alloys (SMAs), rather than nickel–titanium as earthquake energy dissipaters, the influence of ausforming-induced plastic deformation on phase transformations, microstructure, super elasticity and mechanical properties of the shape memory alloy Cu-26Zn-4Al was examined. These specific SMA properties were targeted by applying appropriate parameters of the thermomechanical (the so-called ausforming) process: beta-phase homogenization at 800 °C for 20 min, one-step hot rolling at 800 °C and water quenching. The results showed significant microstructural changes, increased mechanical resistance and change in the phase transformation behavior. The SMA treated by ausforming retained the reversible austenitic–martensitic transformation ability, with the appearance of the super-elastic effect up to 6% of strain recovery. Although some strengthening occurred after hot rolling (an increase in true yield st...
The fuzzy logic controller, which uses an analytic activation function for the defuzzification pr... more The fuzzy logic controller, which uses an analytic activation function for the defuzzification procedure, was applied to the position control of a servo pneumatic drive controlled by a proportional valve. The Gaussian shape of input fuzzy sets, with the possibility of their modification, was used to fuzzify the input signal. The control signal was determined by introducing an analytic function instead of defining the fuzzy rule base. In this way, a conventional 2-D fuzzy rule table base is modified into 1-D fuzzy defuzzification based on an analytic function to calculate the controller output. In this control algorithm, the problem of conventional fuzzy logic control, in terms of the exponential growth in rules as the number of input variables increases, is eliminated. The synthesis controller procedure is adjusted to the flow rate characteristic of the proportional valve. The developed control algorithms are verified by computer simulation and by testing on a real pneumatic rodless...
Hot rolling of CuZn27Al4 shape memory alloy results in the forming of defects in austenitic cryst... more Hot rolling of CuZn27Al4 shape memory alloy results in the forming of defects in austenitic crystals. The defects such as dislocation and deformed boundaries of austenitic grains affect both “ classical” material properties and the specific properties related to shape memory. Rolled and quenched alloy (ausforming treatment) shows hardening proportional to the value of introduced deformation. By increasing the level of true plastic deformation not only the yield stress and tensile strength are increased but also the pseudo yield stress thus making the mechanically induced martensitic transformation more difficult. Besides, the ausforming treatment reduces all the transformation temperatures of the austenitic-martensitic reaction, thus expanding the temperature field of pseudo-elasticity. In spite of the hardening, the thermo-mechanically treated CuZn27Al4 alloy retains the pseudo-elastic shape memory so that favourable combination of strength and transformation behaviour can be achie...
In this paper the hardness and fracture toughness values for nanostructured cemented carbides wer... more In this paper the hardness and fracture toughness values for nanostructured cemented carbides were tested and analyzed. The experimental part included the testing of three samples: WC with 5% cobalt (WC-5Co), WC with 10% cobalt (WC-10Co) and WC with 15% cobalt (WC-15Co). Hardness was tested by Vickers method (HV30) according to HR EN ISO 6507-1: 2005, and fracture toughness was determined by the Palmqvist method according to ISO 28079: 2009. Palmqvist's method uses the length of cracks that propagate from the tip of the Vickers pyramid imprint to determine fracture toughness. The results show that by increasing the amount of cobalt in cemented carbides hardness values drop, and the fracture toughness increases. They also indicate that using nanostructured cemented carbides increases hardness with a slight change in toughness.
Preload plays an important role in the calibration procedure of a testing machine and represents ... more Preload plays an important role in the calibration procedure of a testing machine and represents an inevitable part of the calibration process. Preload affects the calibration results in the form of relative errors of the measuring system of force which is indirectly reflected also on the class of the measuring range. By performing one or several preloading there is a significant change in the values of characteristic relative errors: accuracy, repeatability and reversibility which represent the classification criteria in determining the class. A greater number of preloads makes worse the error of accuracy whereas the error of repeatability and in particular the error of reversibility are reduced in the absolute amount. Furthermore, preload affects also the residual force which remains on the standard measurement instrument after removing load. Already one preload minimizes this residue and thus allows valid testing. Therefore, the preload in checking the testing machine represents ...
Pojava povecane buke i vibracija elektromotora klipnog kompresora ukazala je na postojanje pukoti... more Pojava povecane buke i vibracija elektromotora klipnog kompresora ukazala je na postojanje pukotine na pogonskom kraju vratila. Provedeno je vise nerazornih ispitivanja kao sto su magnetska kontrola (MT), penetrantska kontrola (UT) i ultrazvucna kontrola (UT) kojima se detektirala pukotina pod kutem od 45o ; ; s obzirom na uzdužnu os vratila. Materijal vratila analiziran je na temelju mehanickih svojstava i mikrostrukture. Rezultati ispitivanja pokazali su da na vratilu nije provedena toplinska obrada poboljsavanja vec se radi o normaliziranom celiku s heterogenom feritno-perlitno mikrostrukturom. Takva heterogena mikrostruktra sacinjena od mekse i tvrđe faze nepovoljno utjece na dinamicki opterecene dijelove jer pogoduje pojavi umora materijala. Nadalje, skoro nikakvo zaobljenje u korijenu upustenog dijela za sjediste glave vijka odnosno matice na prirubnici vratila uzrokovalo je koncentraciju naprezanja na mjestu upustenja cime je također smanjena otpornost vratila na pojavu umora...
Original scientific paper Hot rolling of CuZn27Al4 shape memory alloy results in the forming of d... more Original scientific paper Hot rolling of CuZn27Al4 shape memory alloy results in the forming of defects in austenitic crystals. The defects such as dislocation and deformed boundaries of austenitic grains affect both "classical" material properties and the specific properties related to shape memory. Rolled and quenched alloy (ausforming treatment) shows hardening proportional to the value of introduced deformation. By increasing the level of true plastic deformation not only the yield stress and tensile strength are increased but also the pseudo yield stress thus making the mechanically induced martensitic transformation more difficult. Besides, the ausforming treatment reduces all the transformation temperatures of the austenitic-martensitic reaction, thus expanding the temperature field of pseudo-elasticity. In spite of the hardening, the thermo-mechanically treated CuZn27Al4 alloy retains the pseudo-elastic shape memory so that favourable combination of strength and tr...
U radu je istraživan utjecaj parametara rastopnog žarenja na svojstva aluminijske legure. Analizi... more U radu je istraživan utjecaj parametara rastopnog žarenja na svojstva aluminijske legure. Analiziran je utjecaj temperature i trajanja rastopnog žarenja na mikrostrukturu i mehanicka svojstva lijevane AlSiMgMn legure. Uzorci su rastopno žareni na 520°C i 560°C u trajanju 1, 5 i 3 sata. Parametri umjetnog dozrijevanja bili su jednaki za sve uzorke. Na svjetlosnom mikroskopu provedena je kvalitativna i kvantitativna analiza mikrostrukture toplinski obrađenih uzoraka te lijevanog stanja. Na svim uzorcima izmjerena je mikrotvrdoca (HV0, 05 i HV0, 1) i provedeno staticko vlacno ispitivanje kako bi se odredila optimalna temperatura i vrijeme rastopnog žarenja u postupku precipitacijskog ocvrsnuca.
Toplim valjanjem razlicitim iznosima stvarne deformacije (0-1,54mm/mm), provedenim na temperaturi... more Toplim valjanjem razlicitim iznosima stvarne deformacije (0-1,54mm/mm), provedenim na temperaturi između 650C i 800C (ausforming obradba, AF), uvode se defekti u CuZn27Al4-Slitinu. Ovi defekti i mikrostrukturne promjene analizirani su kombinacijom svetlosne i elektronske mikroskopije. Mehanicka svojstva slitine određene su mjerenjem tvrdoce i vlacnim ispitivanjem. Uobicajene metode mjerenja tvrdoce nisu prikladne kod slitina s efektom prisjetljivosti oblika, izuzev mjerenja tvrdoce nisu prikladne kod slitina s efektom prisjetljivosti oblika, izuzev mjerenja s malim opterecenjem, i to stabilnog autenita pri temperaturi > AF. Kod mjerenja tvrdoce vecim opterecenjima pojavljuju se anomalije koje vode do odstupanja izmjerene i stvarne tvrdoce, te je prisutna pojava pseudotvrdoce. Nakon toplog valjanja u podrucju visih temperatura (AF>700C) i izravnog gasenja u vodi javlja se znatno ocvrscenje slitine, dok istom obradbom u podrucju nižih temperatura (AF < 700C) ne dolazi do ocvr...
U radu je istraživan utjecaj parametara rastopnog žarenja na svojstva aluminijske legure. Analizi... more U radu je istraživan utjecaj parametara rastopnog žarenja na svojstva aluminijske legure. Analiziran je utjecaj temperature i trajanja rastopnog žarenja na mikrostrukturu i mehanicka svojstva lijevane AlSiMgMn legure. Uzorci su rastopno žareni na 520°C i 560°C u trajanju 1, 5 i 3 sata. Parametri umjetnog dozrijevanja bili su jednaki za sve uzorke. Na svjetlosnom mikroskopu provedena je kvalitativna i kvantitativna analiza mikrostrukture toplinski obrađenih uzoraka te lijevanog stanja. Na svim uzorcima izmjerena je mikrotvrdoca (HV0, 05 i HV0, 1) i provedeno staticko vlacno ispitivanje kako bi se odredila optimalna temperatura i vrijeme rastopnog žarenja u postupku precipitacijskog ocvrsnuca.
Lomom siljaka ionizacijske elektrode bitno su narusena funkcionalna svojstva elektrode i znacajno... more Lomom siljaka ionizacijske elektrode bitno su narusena funkcionalna svojstva elektrode i znacajno smanjena ucinkovitost elektrofiltera. Pojava loma, u kratkom vremenskom periodu, dovodi se u vezu s vodikovom krhkosti potpomognutom dinamickim opterecenjem tijekom potresanja elektrode. Ovaj oblik napetosne korozije nastupa na vlacnom napregnutim mjestima pod djelovanjem agresivnog medija. Naime, za vrijeme rada postrojenja, a posebice tijekom njegova zastoja zbivaju se kemijske reakcije kojima nastaje otopina sumporne kiseline (H2SO4). Reakcijom agresivne kiseline i željeza oslobađa se atomarni vodik koji difundira u kristalnu resetku željeza i time uzrokuje izvitoperenje resetke. Inducirana naprezanja superponiraju se s postojecim naprezanjima, tj. naprezanjima u radu, zaostalim naprezanjima toplinskog porijekla (zavarivacke napetosti) i naprezanjima uslijed hladne deformacije. Kada ukupno naprezanje dostigne vrijednost vlacne cvrstoce dolazi do loma.
The research results of the study conducted show the effect of the change in the voltage of the d... more The research results of the study conducted show the effect of the change in the voltage of the developing drum and the voltage of the squeegee roller, which in fact are the first and last part of the development process and this is subsequently one of the phases of indirect electrophotographic printing on the recycling mechanism and characteristics of recycled fibers. The substrates bases are woodfree uncoated paper and coated paper intended for LEP printing technology, with the purpose of achieving high quality double-sided printing. The results confirm a decrease in the specks count and a larger speck area on a handsheet prior to flotation, when increasing the negative voltage of the developing drum. The specks count is higher on the handsheet obtained by recycling prints on uncoated paper versus coated paper. A greater speck count is removed by the flotation of prints on uncoated paper (approximately 73%), unlike coated paper (approximately 28%). When dealing with non-deinked ha...
In this study, aluminum foams reinforced with different steel elements were produced by the AluLi... more In this study, aluminum foams reinforced with different steel elements were produced by the AluLight process. The master alloy AlMgSi0.6 was used as the matrix material, titanium hydride (TiH2) powder was used as a foaming agent, and steel wire, cylindrical steel mesh and flat steel mesh were used as reinforcing elements. Reinforcements were placed inside the mold, along with the precursors, and samples were manufactured by gas releasing particles in a semi-solid state. To examine the effect of the reinforcements on specific energy absorption, quasi-static uniaxial compression tests were carried out, with a constant separation rate of 1 mm/s. From the tested results, the energy absorption per unit volume and specific energy absorption efficiency were calculated and then also statistically evaluated. The results showed that examined shapes of reinforcements affect differently specific energy absorption and its efficiency, compared to non-reinforced aluminum foams. The best result obt...
Journal of Materials Research and Technology, 2021
Abstract The generated process losses such as broken ware from shaping, if not recycled internall... more Abstract The generated process losses such as broken ware from shaping, if not recycled internally, are considered as waste. Furthermore, the collected process losses are provided to external recycling companies or waste disposal facilities. This study investigated the recycling potential of waste alumina powder, which was accumulated during industrial machining of the ceramic green body. The samples containing up to 20 dwb. % (dwb – weight amounts based on dry matter) of powdered waste alumina were prepared by slip casting method and conventionally sintered at various sintering conditions according to Box-Behnken design. Sintered samples were characterized for density, microstructure, hardness, and indentation fracture toughness and compared with samples made of pure commercial alumina. The study shows that the addition of waste alumina up to 20 dwb. % sintered at higher sintering temperature with dwell time 1–3 h did not negatively affect the hardness, nor the indentation fracture toughness of the sintered samples. The enabled recycling potential of waste alumina powder can have direct positive environmental impact, although economic benefits cannot be ignored.
Samples of nanostructured hardmetals were sintered as a substrate material by applying two differ... more Samples of nanostructured hardmetals were sintered as a substrate material by applying two different powder metallurgy processes. The starting powders had an average grain size from 95 nm to 150 nm. The plasma-assisted chemical vapour deposition technique was used for the deposition of coatings and two coating systems, i.e. the 2 µm titanium nitride and 3.8 µm titanium carbon nitride were produced. Scratch tests were conducted with an increasing load ranging from 5 to 200 N. Critical normal loads of coating delamination during the scratch tests were registered. The sliding wear resistance was investigated with a ball-on-disc test. The ball-on-disc test showed that the porosity of the sintered product had the highest impact on the wear volume loss. Nanostructured hardmetals showed a great potential for application of plasma-assisted chemical Vapour deposition.
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