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1

Mechanical Properties of Polymer Coatings Containing HAp and Active Substance on a Metal Substrate

Goldsztajn Karolina, Lisoń-Kubica Julia, Jaworska Joanna, Jelonek Katarzyna, Kajzer Wojciech, Szewczenko Janusz

Tribologia

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2023

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nr 2

17--25

EN

Titanium alloys are currently widely used in implantation, especially in orthopaedics. However, undesirable reactions caused by aluminium and vanadium ions released from the surface of the most commonly used alloys, Ti6Al4V and Ti6Al7Nb, result in the need to modify the surface of the material to improve biocompatibility. Among the available modification methods, one can mention the application of biodegradable polymer coatings, which, apart from improving biocompatibility by limiting the penetration of alloying element ions into the tissue environment, can also be a matrix for the release of mineral (HAp) and active substances. The paper attempts to determine the mechanical properties of PLGA polymer coatings containing nanoparticle hydroxyapatite and an active substance (dexamethasone) applied with the ultrasonic spray coating method on a Ti6Al7Nb alloy substrate. The scope of the research included: surface topography testing using an optical profilometer, coating adhesion testing to the substrate using the scratch test method and tribological testing (Pin-On-Disc method).

PL

Stopy tytanu znajdują obecnie szerokie zastosowania implantacyjne, szczególnie w ortopedii. Jednakże niepożądane reakcje wywoływane przez jony glinu i wanadu uwalnianie z powierzchni najczęściej wykorzystywanych w praktyce stopów Ti6Al4V oraz Ti6Al7Nb skutkują koniecznością modyfikacji powierzchni materiału w celu poprawy biokompatybilności. Wśród dostępnych metod modyfikacji wymienić można nakładanie biodegradowalnych powłok polimerowych, które poza poprawą biokompatybilności poprzez ograniczenie przenikania jonów pierwiastków stopowych do środowiska tkankowego stanowić mogą także matrycę dla uwalniania substancji mineralnych (HAp) oraz aktywnych. W pracy podjęto próbę określenia własności mechanicznych powłok polimerowych z PLGA, zawierających nanocząsteczkowy hydroksyapatyt oraz substancję aktywną (deksametazon), nakładanych metodą natryskiwania ultradźwiękowego na podłoże ze stopu Ti6Al7Nb. Zakres przeprowadzonych badań obejmował badania topografii powierzchni z wykorzystaniem profilometru optycznego, badania adhezji powłok do podłoża metodą scratch test oraz badania tribologiczne (metoda Pin-On-Disc).

2

Effect of Microalloying with Ti on the Corrosion Behaviour of Low Carbon Steel in a 3.5 wt.% NaCl Solution Saturated with CO2

Sheikh Ali R.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 1

5--10

EN

A problem is defined to investigate the effect of titanium traces on the corrosion behaviour of low carbon steel. In theory titanium effects surface properties like abrasion resistance in medium carbon steels and corrosion resistance in low as well as medium carbon steels. The present research as indicated by the topic is aimed to experimentally mark the effect of titanium traces on corrosion resistance in the available low carbon steel specimens. The effect of microalloying with titanium (i.e.0.02wt.%) on the corrosion behavior of low carbon steel in a 3.5 wt.% NaCl solution was studied by electrochemical, SEM, and Raman spectroscopy techniques. The electrochemical results showed that the corrosion of the Ti-bearing steel improved by around 30% compared with the Ti-free steel. The titanium microalloying led to the formation of a more compact corrosion product layer on the metal surface. The SEM analysis showed that the Ti-bearing sample had a smoother surface compared with the Ti-free steel.

3

Measurement and analysis of pocket milling features in abrasive water jet machining of Ti-6Al-4V alloy

Natarajan Yuvaraj, Raj K. L. Naresh, Tandon Puneet

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e42, 2023

EN

The present work deals with the size effect of abrasive water jet milling parameters on the square pockets of Ti-6Al-4V alloy. In this study, the abrasive mesh size, water jet pressure and traverse rate were chosen as milling variables and their effect on pocket features such as depth of cut, undercut, material removal rate, and surface roughness were examined. This study also characterizes the milled pocket surfaces under different milling conditions. Most of the measurements and surface characterizations were done using the Dino-Lite Digital Microscope. For both #80 and #100 abrasives, the AWJ-milled pockets were formed with variations in depth milled and rugged surface by increasing the water jet pressure from 175 to 200 MPa under all the selected traverse rate conditions. Also, the variations of depth of cut in successive trajectories found to have a speed bump effect. At these settings, distribution of energy to the work material was more due to deceleration of jet in the boundary close by and changes made in the feed directions in raster path from 0° to 90° at a step-over distance of 0.2 mm. This yielded undercuts in the milled pocket corners. However, there was a significant reduction in the undercut with a water jet pressure of 125 MPa and a traverse rate of 3500 mm/min were employed. Besides, the abrasive mesh size #100 had a better surface topography, and also strong jet footprints were observed with mesh size of #80. Based on the experiments results, the size effect of different milling parameters was seen having influence on the pocket geometry and surface features.

4

Bi-axial stress state hot bulging behavior and plane-stress visco-plastic material modelling of TA32 sheets

Peng Heli, Luo Zhiqiang, Qu Shuguang, Shi Wenzhan, Fu Kunning, Xiao Wenchao, Zheng Kailun

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no e167, 2023

EN

Bi-axial state is the dominant stress state experienced by the sheet metal during various forming processes, which requires a thorough understanding and modelling for process designs. In this paper, effects of equal bi-axial stress-state on the hot deformation behavior of titanium alloys are thoroughly investigated using hot bulging tests, and is further compared to the uniaxial stress state. Firstly, a specific hot bulging test device enabling a uniform temperature field and constant control of strain rate was established, using which, systematic hot bulging tests at various temperatures (750–850 °C) and strain rates (0.001–0.1 s−1) of the near-alpha phase TA32 sheets were conducted to determine the hot equal bi-axial bulging behavior. Based on the testing data of force and geometry variations of bulged domes, the equivalent stress–strain curves were calculated. Secondly, a plane-stress visco-plastic plane-stress model of near-alpha TA32 sheets was developed for the first time, enabling both the uniaxial and biaxial flow behavior and forming limits to be precisely predicted. The prediction accuracies for uniaxial and biaxial cases are 93.5% and 89%, respectively. In the end, the uniform deformation resulting from the strain and strain rate hardening was determined, which contributes to the understanding of the stress-state effect on hardening preliminarily. The plane stress visco-plastic model provides an efficient and reliable material model for finite element (FE) simulations of hot forming titanium alloy sheets.

5

Analysis of mechanical and microstructural characteristics of plunger-assisted ECAP strengthened Ti-6Al-4V alloy sheets

Sahoo Partha Sarathi, Meher Arabinda, Mahapatra Manas Mohan, Vundavilli Pandu Ranga, Pandey Chandan

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e194, 2023

EN

Often known as the workhorse among titanium alloys, Ti-6Al-4 V has been useful in the aerospace and biomedical sectors. For further enhancement of the mechanical characteristics of Ti-6Al-4 V alloy, its sheets procured for the present study have been subjected to equal channel angular pressing (ECAP) using a die setup having a channel angle of 120° and corner angle of 10° at its forming temperature of 650 °C followed by appropriate annealing treatments. Microstructural analysis post the hot-ECAP process has demonstrated ultrafine grain (UFG) refinement because of this severe plastic deformation technique of ECAP. Phase analysis has further substantiated the reduction of β-phase in the alloy as a controlling factor in improving the mechanical properties. As a result, the room temperature hardness and tensile strength have improved by 10% and 15%, respectively, due to a drastic reduction in grain size from ~ 906 nm to ~ 359 nm, which is in line with the well-established Hall–Petch equation. Basic finite element modeling has been studied as concerned with the sustainability and feasibility of the die setup to withstand the heavy metal forming forces involved in the ECAP of Ti-6Al-4 V. This success in processing Ti-6Al-4 V by a single pass of an ECAP using channel angle of 120° and corner angle of 10° under a controlled equivalent strain further opens doors for incorporating additional steps and criteria to achieve even higher grain refinement and strength enhancements thereby catering to the needs for manufacturing the assault vehicles and bioimplants.

6

Advances in friction stir welding of Ti6Al4V alloy complex geometries: T-butt joint with complete penetration

Ambrosio Danilo, Wagner Vincent, Vivas Javier, Dessein Gilles, Aldanondo Egoitz, Cahuc Olivier

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e182, 2023

EN

In this work, the friction stir weldability of Ti6Al4V T-joints has been investigated. Its aims are: (i) to study the influence of tool and welding parameters on weld quality, (ii) to assess the joints’ mechanical strength to foresee future applications, and (iii) to characterize Co-based FSW tools’ wear by following the wear during the tests. Welds’ defectivity is studied by cross-section macrographies analysis. Independently from welding parameters and tools, internal voids are avoided, and a suitable weldability window is identified. Microstructure observations have corroborated temperatures below the -transus point even in the nugget zone, guaranteeing joints’ maximum mechanical strengths at 96% and 87% of the base material for UTS and Y, respectively. Contrarily, elongation at break is very low, without reaching 20% of the base material. The failure is linked to section thinning and kissing bond defects at the joints’ corners. Additionally, tool wear proved to be a critical issue while friction stir welding Ti6Al4V. The inner part of the shoulder is the most sensitive to wear. The consequent high wear rate might be a problem for mass production. The work established the pertinence of assembling complex geometries of Ti6Al4V using friction stir welding, considering weld quality and the mechanical strength achieved. However, critical factors such as section thinning, kissing bond, and tool wear must be carefully addressed to avoid joints’ low elongation at break and to guarantee their mechanical strength.

7

Microstructural and Micromechanical Tests of Titanium Crowns

Ryniewicz Wojciech, Bojko Łukasz, Pałka Paweł, Osada Piotr, Ryniewicz Andrzej

Tribologia

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2022

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nr 4

61--72

EN

Fixed prosthetic restorations must meet the health requirements in terms of the protection of the tissues of the oral cavity, biomechanical requirements for optimal tissue stress and the strength and wear resistance of the structure, aesthetic requirements related to the location of the gingival margin, as well as the shape, thickness, and colour of the veneers. The aim is to evaluate the impact of manufacturing technology on the microstructure and micromechanical parameters of titanium crowns. The material of the analysis are prosthetic crowns made of Ti6Al4V alloy for the maxilla premolars and the mandible molars, produced using two technologies: Selective Laser Melting (SLM) and CAD/CAM milling. Crown structures were evaluated on the basis of examinations of the microstructure and surface layer of the chamfers, micromechanical parameters in axial sections perpendicular to the dental arches, and the accuracy of mapping the internal shape in sections with horizontal planes perpendicular to the axis of the abutment tooth. The results of this work can be used in a clinical setting. They allow the evaluation of what is the impact of the technology of producing the supporting substructure on the structure of the prosthetic crown. The strength requirements in both technologies are met, while the higher value of the microhardness of the titanium SLM substructure, compared to the milled one, increases the stiffness of the structure under conditions of biomechanical excitation. The errors in mapping the internal shape of the crowns are comparable and slightly higher during sintering.

PL

Stałe uzupełnienia protetyczne powinny spełniać wymagania zdrowotne w aspekcie zabezpieczenia tkanek jamy ustnej, wymagania biomechaniczne dotyczące optymalnego wytężenia tkanek oraz wytrzymałości i odporności na zużycie konstrukcji, wymagania estetyczne związane z usytuowaniem obrzeża dodziąsłowego, a także kształtem, grubością i kolorem licowania. Celem jest ocena wpływu technologii wytwarzania na mikrostrukturę i parametry mikromechaniczne koron tytanowych. Materiałem analizy są korony protetyczne ze stopu Ti6Al4V na zęby przedtrzonowe szczęki i trzonowe żuchwy wytwarzane dwoma technologiami: Selective Laser Melting (SLM) i frezowania CAD/CAM. Konstrukcje koron oceniano na podstawie badań mikrostruktury i warstwy wierzchniej stopni, parametrów mikromechanicznych w osiowych przekrojach prostopadłych do łuków zębowych oraz dokładności odwzorowania kształtu wewnętrznego w przekrojach płaszczyznami horyzontalnymi, prostopadłymi do osi zęba filarowego. Wyniki tej pracy mogą być wykorzystane w warunkach klinicznych. Pozwalają ocenić, jaki jest wpływ technologii wytworzenia podbudowy nośnej, na konstrukcję korony protetycznej. Wymagania wytrzymałościowe w obu technologiach są spełnione, przy czym wyższa wartość mikrotwardości podbudowy tytanowej z SLM, w porównaniu do frezowanej, wpływa na zwiększenie sztywności konstrukcji w warunkach wymuszeń biomechanicznych. Błędy odwzorowania kształtu wewnętrznego koron są porównywalne i nieco wyższe przy spiekaniu.

8

Powłoki ochronne na bazie winylotrójmetoksysilanu (VTMS) z dodatkiem surfaktantu (Triton X-100) do zastosowań w implantologii

Kierat Oliwia, Dudek Agata, Adamczyk Lidia

Ochrona przed Korozją

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2022

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nr 4

107--111

PL

W pracy przedstawiono analizę właściwości fizykochemicznych powłok na bazie winylotrójmetoksysilanu z dodatkiem surfaktantu – Tritonu X-100 – osadzonych na tytanie Grade 2 oraz stopie tytanu Ti6Al4V. Oceniono adhezję powłok do podłoża, grubość powłok, wpływ wytworzonych powłok na odporność korozyjną materiałów, a także wykonano analizę mikrostruktury i parametrów struktury geometrycznej powierzchni powłok przed badaniami korozyjnymi oraz po nich. Przyczepność powłok analizowano za pomocą taśmy ScotchTM. Odporność korozyjną analizowano za pomocą potencjodynamicznych krzywych polaryzacji w symulowanym płynie ustrojowym odwzorowującym warunki ludzkiego organizmu w celu oceny powłok pod kątem ich zastosowania w implantologii. Grubość powłok określono za pomocą mikroskopu cyfrowego KEYENCE VHX-7000 oraz miernika Testan DT-20 AN 120 157.

EN

This paper presents an analysis of the physicochemical properties of coatings based on vinyltrimethosysilane with the addition of Triton X-100 surfactant deposited on titanium Grade 2 and titanium alloy Ti6Al4V. The adhesion of coatings to the substrate, the thickness of the coatings, the influence of the produced coatings on the corrosion resistance of materials were assessed, and the microstructure and parameters of the geometric structure of the coatings surface were analyzed before and after corrosion tests. The adhesion of the coatings was analyzed with ScotchTM tape. Corrosion resistance was analyzed using potentiodynamic polarization curves in a simulated body fluid mapping the conditions of the human body in order to evaluate the coatings for their application in implantology. The thickness of the coatings was determined using the KEYENCE VHX-7000 digital microscope and the Testan DT-20 AN 120 157 meter.

9

Finite element analysis on prosthetic leg under different loads and flexion angles for medical applications

Konada Naresh Kumar, Koka Naga Sai Suman

Journal of Mechanical and Energy Engineering

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2022

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Vol. 6, No 2

1--12

EN

Prosthetic legs are mainly used to perform leg amputations more easily and sometimes the appearance is similar to a real leg. Different types of legs have been developed in recent days to be used in specific fields like running, cycling in sports and normal walking. The selection of materials and load bearing capacity of a leg determines its usage for any field of application. The behavior of prosthetic legs can be assessed properly by performing a finite element analysis on it with varying material properties and loads before it undergoes a designing and manufacturing stage. In the current study, Al alloy, Ti alloy, unidirectional Carbon fiber epoxy (UDCFE) and combined composite material which include (CF, UDCFE and Ti alloy) are used as materials for the prosthetic leg. A prosthetic leg model of C Type with its main parts being the sleeve, the rod and the base foot was designed initially by using the Solid Works 2010 software and the assembled file was imported to Ansys Workbench 2020 to perform a static and fatigue analysis. The static analysis was performed under four different load conditions, i.e. 60 kg, 70 kg, 80 kg and 90 kg, considering the different human weights of the body. A fatigue analysis was done by using the Soderberg method and applying a sinusoidal varying load for low cycle fatigue conditions. Theoretical calculations were also performed at various inclinations of foot 10°, 20°, and 30° with the ground and stresses were evaluated using finite element equations. The results obtained theoretically were compared with the analytical results. The best material which provided the lesser value of deformation and sustaining more loads with a lower value of the damage factor was selected for the design. Further experimental studies were suggested based on the results obtained from this work.

10

Wpływ temperatury starzenia na mikrostrukturę i wybrane właściwości mechaniczne stopu Ti24Nb4Zr8Sn

Dąbrowski Robert

Inżynieria Materiałowa

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2022

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Vol. 43, nr 5

9--15

PL

Celem pracy była ocena mikrostruktury i wybranych własności mechanicznych stopu Ti24Nb4Zr8Sn w stanie po przesycaniu, tj. oziębianiu w wodzie z wybranej temperaturze wygrzewania (800°C) i starzeniu w zakresie temp. 350–600°C. Wyniki badań wskazały na obecność w mikrostrukturze stopu fazy β w stanie przesyconym oraz wydzieleń fazy α, począwszy od temperatury starzenia 400°C. Twardość próbek stopu wyznaczono w stanie po przesycaniu oraz w całym zakresie temperatur starzenia. W stanie przesyconym (oziębionym w wodzie od 800°C) odnotowano minimalną twardość stopu, tj. 236 HV, której odpowiadała największa odporność na pękanie (KV = 109,5 J). Wraz ze wzrostem temperatury starzenia w zakresie 350–600°C obserwowano spadek odporności na pękanie stopu. Wykazano, że w stanie po przesycaniu oraz przesycaniu i starzeniu przełomy próbek są quasi-kruche, o różnym udziale objętościowym przełomu międzykrystalicznego i transkrystalicznego.

EN

The aim of the study was to evaluate the microstructure and selected mechanical properties of the Ti24Nb4Zr8Sn alloy in the state after supersaturation, i.e. cooling in water from the selected annealing temperature (800°C) and ageing in the temperature range 350–600°C. The test results indicated the presence of the β phase in the supersaturated state in the alloy microstructure and the α phase precipitates – starting from the ageing temperature of 400°C. The hardness of the alloy samples was determined in the state after supersaturation and throughout the entire ageing temperature range. In the supersaturated state (cooled in water from 800°C), the minimum hardness of the alloy was recorded, i.e. 236 HV, which corresponds to the highest impact energy (KV = 109.5 J). A decrease in the fracture toughness of the alloy was observed with the increase in the ageing temperature in the range of 350–600°C. It has been shown that in the state after supersaturation, supersaturation and ageing, the fractures of the samples are quasi-brittle with a different volume fracture of the intercrystalline and transcrystalline fracture.

11

Assessment of gold with titanium alloy weldability in conditions of a dental technique laboratory

Jania G., Żmudzki J., Topolska S.

Archives of Materials Science and Engineering

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2022

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Vol. 118, nr 1

36--41

EN

Purpose: In dental practice, there is necessary to weld gold with titanium under the conditions of a dental technique laboratory, which is difficult. The aim was to assess the weldability of pure gold with the titanium alloy Ti6Al4V using a prosthetic laser welding machine. Design/methodology/approach: Gold wire in a diameter of 0.4 mm made with the use of a jewellery drawbar (GOLDPORT, Szczecin, Poland) was welded to a titanium alloy Ti6Al4V substrate of dental implant abutment screw (MegaGen). Dental laser welding parameters (Bego Laser Star T plus) were 230 V; 6.5 ms; 2.5 Hz; laser spot 0.3 mm, and argon blow. Samples were included in resin, ground (500-4000 SiC), polished (Al2O3 suspension) and etched (Kroll solution) per 20 s before observation under a light microscope. Findings: There were well-welded and poorly joined zones. The discontinuities and voids there were not visible or sparse next to the initial weld point. Dendritic structure at well-welded remelting zones and two-phase microstructure of titanium and Ti3Au phase were found. The heat-affected zone was about of 20 microns. Research limitations/implications: Light microscopy was used, and precise phase identification required further investigations. Weld strength assessment requires further micro-hardness and load-bearing ability tests. Weldability concerns the model system with pure gold. Practical implications: In the case of elements with dimensions below 0.4 mm, the use of a laser with a smaller spot should be considered for better control of the remelting zone and mechanical positioning of the elements in order to stabilize and avoid discontinuities and voids. Originality/value: Prosthetic laser welding with a laser spot about of 0.3 mm allows to obtain well-welded parts of 0.3 mm in diameter under stable stitching conditions and higher than 0.4 mm in dimensions.

12

Zastosowanie stopów metali lekkich w bezzałogowych statkach powietrznych

Muszyński Tomasz, Kmiotek Małgorzata, Kordos Adrian, Ficek Daniel

Obróbka Metalu

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2021

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nr 2

42--49

PL

W ostatnich latach obserwuje się znaczny wzrost użycia bezzałogowych statków powietrznych (BSP) w licznych zastosowaniach komercyjnych, a także wojskowych. Obecnie szacuje się, że na świecie istnieje przeszło 10 mln tego typu obiektów, wykorzystywanych od celów od hobbystycznych po profesjonalne, których wartość przekracza wiele milionów dolarów. BSP, zwane powszechnie dronami muszą cechować się małą masą i dużą sprawnością układu napędowego i zasilania, które pozwalają na długi czas nieprzerwanej pracy w powietrzu zwiększając obszar potencjalnych zastosowań. Jest to szczególnie istotne w przypadku obiektów latających używanych w zastosowaniach profesjonalnych. W zależności od zastosowania i liczności serii, do ich budowy wykorzystuje się wiele różnych materiałów w szczególności kompozytów. Jednakże bezzałogowe aparaty latające używane do celów militarnych, a także komercyjnych, np. w transporcie i rolnictwie muszą dodatkowo cechować się wytrzymałą i stabilną konstrukcją pozwalającą na przenoszenie dużych obciążeń. Z tej przyczyny coraz częściej do budowy BSP używa się stopów metali lekkich w szczególności aluminium, magnezu i tytanu. Ważnym argumentem przemawiającym za używaniem stopów metali lekkich są również względy ekologiczne gdyż niedostatecznie jeszcze są rozwinięta procesy recyklingu materiałów kompozytowych.

EN

In recent years, there has been a significant increase in the use of unmanned aerial vehicles(UAV) in numerous commercial as well as military applications. Currently, it is estimated that there are more than 10 million such objects in the world, used for purposes ranging from hobby to professional, with a value exceeding many millions of dollars. UAV, commonly referred to as drones, must be characterized by low weight and high efficiency of the propulsion and power systems that allow for long periods of continuous operation in the air increasing the area of potential applications. This is especially important for flying objects used in professional applications. Depending on the application and the number of series, many different materials are used for their construction, especially composites. However, unmanned aerial vehicles used for military as well as commercial purposes, such as transport and agriculture, must additionally feature a robust and stable design to carry heavy loads. For this reason, lightweight metal alloys, in particular aluminum, magnesium and titanium, are increasingly being used to build UAV. An important argument for the use of light alloys are also ecological considerations as recycling processes for composite materials are still underdeveloped.

13

Change in the surface structure and the oxide layer of the Ti6Al4V ELI alloy as a result of mechanical and heat treatment

Szota Michał

Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

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2021

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Nr 2

12--21

EN

Surface treatment, both mechanical, chemical and thermal causes a number of changes to the external structure of meterial details. The obtained properties are intended to improve the quality of material details made of a given alloy or pure metal. This paper presents the results of mechanical surface treatment to the thickness of the oxide layer after heat treatment of the TU6Al14V ELI alloy. The experiments were performed for a rod with a diameter of 5 mm cut into semicircular slices. The samples were mechanically activated by mechanical treatment of the surface: sandblasting with glass balls for 5 minutes, sanded with 40, 180, 220 and 800 grit sandpaper for 7.5 and 15 minutes. Using an optical microscope, the microstructure of the samples etched with Kroll's solution was assessed and the surface roughness parameters were measured. The next step was to carry out the heat treatment (at the temperature of 550 oC, for 5 hours), and then the roughness parameters and the thickness of the oxide layer were measured using a scanning microscope. The conducted research has shown that mechanical treatment of the surface resulting in an increase in surface development causes an increase in the thickness of the oxide layer formed during heat treatment. However, machining to reduce surface development, such as polishing, reduces the thickness of the oxide layer. The test results can be used to obtain the desired thickness of the oxide layer in the production of elements requiring increased resistance to wear or corrosion.

14

Microstructure and mechanical properties of TC4 titanium alloy hollow shaft formed by cross wedge rolling

Feng Pengni, Yang Cuiping, Wang Baoyu, Li Junling, Liu Ronge

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

737--751

EN

Production of hollow shafts satisfying mechanical performance requirements can well meet the needs of lightweight. The purpose of this work is to investigate the effect of cross wedge rolling (CWR) process parameters on microstructure and mechanical properties of TC4 titanium alloy hollow shafts, so as to ensure the feasibility of forming TC4 titanium alloy hollow shaft by CWR. The results demonstrate that the initial deformation temperature, area reduction, wall thickness, and mandrel have significant effects on the volume fraction of primary alpha phase (fα_p), morphology of alpha phase and interface of alpha/beta phase. The decrease of the fα_p, the increase of fine secondary alpha phase content and the increase of the number of alpha/beta phase interfaces can increase the strength of TC4 alloy hollow shafts, but decrease the elongation. When the initial deformation temperature is 950 °C, the contribution of the thick secondary alpha phase is similar to that of the primary alpha phase, resulting in the decrease of strength. The strength is further improved owing to the grain refinement with the increase of area reduction to 60%. The strength decreases as the wall thickness increases owing to the non-uniform microstructure distribution, which can be improved by increasing the area reduction appropriately. The comprehensive mechanical properties of the workpiece rolled with a mandrel are evidently higher than that rolled without a mandrel. Under any forming condition in this work, every fracture surface is covered with abundant dimples and voids, showing good ductile fracture characteristics.

15

Constitutive modeling of softening mechanism and damage for Ti–6Al–4V alloy and its application in hot tensile simulation process

Yang Xiaoming, Wang Baoyu, Zhou Jing, Xiao Wenchao, Feng Pengni

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 2

479--491

EN

In this paper, a unified viscoplastic constitutive model for Ti–6Al–4V alloy coupling with damage and softening mechanisms was established to predict the flow behaviors and damage evolution in hot tensile process. To obtain the flow behaviors of Ti–6Al–4V alloy, the hot tensile tests were performed at temperatures between 750 °C and 850 °C and strain rates of 0.01–1 s−1. Then the evolution of microstructure was investigated by scanning electron microscope (SEM) under hot tensile conditions. Otherwise, the macro-fracture morphology of the tensile specimen was observed by SEM. The flow stress and microstructure evolution were predicted based on the set of constitutive model. The constitutive model was embed in ABAQUS by coding a user-defined material subroutine. The results show that the flow stress increases with the temperature decreasing and the strain rate increasing. By comparing the experimental and calculated results, the flow stress and damage evolution can be accurately predicted by the constitutive model. The fracture due to damage can be well predicted by the simulation model, indicating the good predictability of the constitutive model.

16

Comprehensive analysis of tribological factor influence on stress-strain and thermal state of workpiece during titanium alloys machining

Stupnytskyy Vadym, She Xianning

Archive of Mechanical Engineering

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2021

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LXVIII, nr 2

227--248

EN

The article describes how different friction coefficients under certain cutting conditions and parameters affect the formation of the stress-strain and thermal states of the product when titanium alloy machining. A new research methodology is used for the study. Firstly, in the initial data for simulation, each time a different declared coefficient of friction is proposed, and every such task of the cutting process modelling is solved for various cutting parameters. The second stage analyzes how these coefficients influence the stress-strain and thermodynamic state of the workpiece and tool during cutting, as well as the tool wear dynamics. In the third stage of the study, ways for ensuring these analytically-grounded tribological cutting conditions are proposed. The analysis of different wear criteria in the simulation models of titanium alloys cutting is carried out. Experimental studies confirm simulation results.

17

Multivariate modelling of effectiveness of lubrication of Ti-6Al-4V titanium alloy sheet using vegetable oil-based lubricants

Trzepieciński Tomasz, Szpunar Marcin

Advances in Materials Science

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2021

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Vol. 21, nr 2(68)

26--39

EN

The article presents the results of modelling the friction phenomenon using artificial neural networks and analysis of variance. The test material was composed of strip specimens made of 0.5-mm-thick alpha-beta Grade 5 (Ti-6Al-4V) titanium alloy sheet. A special tribotester was used in the tests to simulate the friction conditions between the punch and the sheet metal in the sheet metal forming process. A test called the strip drawing test has been conducted in conditions in which the sheet surface is lubricated with six environmentally friendly oils (palm, coconut, olive, sunflower, soybean and linseed). Based on the results of the strip drawing test, a regression model and an artificial neural network model were built to determine the complex interactions between the process parameters and the friction coefficient. A multilayer perceptron with one hidden layer and eight neurons in this layer showed the best fit to the training data. The network training was conducted using three algorithms, i.e. Levenberg-Marquardt, back propagation and quasi-Newton. Taking into consideration both the coefficient of determination R2 (0.962) and S.D. ratio (0.272), the best regression characteristics were presented by the network trained using the Levenberg-Marquardt algorithm. From the response surfaces of the quadratic regression model it was found that an increase in the density of lubricant at a specific pressure causes a reduction in the coefficient of friction. Low density and high kinematic viscosity of the oil leads to a high coefficient of friction.

18

Zależność właściwości ochronnych powłok silanowych wytworzonych na tytanie Grade 2 i Ti6Al4V od stężenia składnika – winylotrójmetoksysilanu (VTMS)

Kierat Oliwia, Dudek Agata, Adamczyk Lidia

Ochrona przed Korozją

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2020

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nr 11

364--368

PL

W niniejszej pracy przedstawiono analizę właściwości antykorozyjnych powłok silanowych osadzonych na tytanie Grade 2 i stopie tytanu Ti6Al4V. Do nałożenia powłok składających się z winylotrójmetoksysilanu (VTMS), etanolu (EtOH) oraz kwasu octowego (AcOH) wykorzystano metodę zanurzeniową. Przeanalizowano wpływ stężenia VTMS na odporność na korozję tytanu i jego stopu. Odporność na korozję nałożonych powłok analizowano w środowisku siarczanowym (pH=2) oraz w płynie Ringera (pH≈6), za pomocą krzywych potencjodynamicznych. Analizowano morfologię powierzchni i mikrostrukturę przy wykorzystaniu skaningowego mikroskopu elektronowego oraz mikroskopu optycznego oraz sprawdzono przyczepność powłok do podłoża przy pomocy taśmy ScotchTM.

EN

This paper presents the results of anti-corrosive properties of silane coatings deposited on titanium Grade 2 and the Ti6Al4V titanium alloy. The dip method was used to apply the coatings consisting of vinyltrimethoxysilane (VTMS), ethanol (EtOH) and acetic acid (AcOH). The influence of VTMS concentration on the corrosive properties of titanium and its alloy was analyzed. The protective properties of the applied coatings were analyzed in the sulphate environment (pH = 2) and in the Ringer’s liquid (pH≈6). The corrosion resistance of the produced coatings was assessed using potentiodynamic curves. Surface morphology and microstructure were analyzed using a scanning electron microscope and an optical microscope, and the adhesion of coatings to the substrate was checked using ScotchTM tape.

19

Studying the wear of titanium thread of aircraft fuel filter

Gronek Sebastian, Szczepaniak Paweł, Jastrzębski Grzegorz, Winiarska Urszula, Kamiński Maciej, Krukowski Marek

Journal of KONBiN

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2020

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Vol. 50, iss. 2

83--105

EN

The article presents the tests that were conducted to examine the possibility of the fuel filter shank’s thread shearing under the impact of hydrostatic pressure. Increasedwear due to friction was confirmed on the threads of the titanium shanks that were tested, together with significantly reduced wear of the mating threads and steel sleeves. Shearing tests confirmed that to shear a thread that is worn to a degree similar to the threads that were tested, it is necessary to apply eight times more static pressure than the maximum pressure in the filter. A comparison of the shape of the coils of the thread that was subjected to the pressure test with the thread from the damaged filter demonstrated a significant difference in the wearing of these elements due to friction.

PL

W artykule przedstawiono przeprowadzone badania możliwości ścięcia gwintu trzonu z filtra paliwa pod wpływem działania ciśnienia hydrostatycznego. Potwierdzone zostało występowanie znacznego zużycia przez tarcie badanych gwintów tytanowych trzonów oraz wyraźnie mniejszego zużycia współpracujących z nimi gwintów stalowych tulejek. Próby ścinania wykazały, że do ścięcia gwintu zużytego w stopniu zbliżonym do badanych niezbędne jest zastosowanie 8-krotnie większego ciśnienia statycznego niż maksymalne ciśnienie występujące w filtrze. Porównanie kształtu nitek gwintu trzonów poddanych próbie ciśnieniowej z gwintem z filtra, który uległ awarii, wykazało znaczną różnicę w zużyciu tych elementów przez tarcie.

20

The kinetics of phase transformations during continuous cooling of Ti13Nb13Zr alloy

Dąbrowski Robert

Inżynieria Materiałowa

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2020

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Vol. 41, nr 1

3--9

EN

The phase transformations during continuous cooling from the single phase β range in the Ti13Nb13Zr alloy have been analysed. Investigations were carried out by the dilatometric method using L78 R.I.T.A. dilatometer of the LINSEIS Company. The received results have been illustrated by selected dilatometric curves ΔL = f(T), (where: ΔL is the length change of the sample, T – temperature). On the basis of the curves, the temperature at which diffusion and non-diffusion transformations start and finish has been determined. The cooling curves was differentiated ΔL/T = f(T). Additionally, changes in the alloy microstructure during cooling down from the single phase β range have been analysed. After cooling from 780°C the diffusion martensitic transformation β → α” and probably massive transformation β → αM occur in the alloy cooling rate range from 160–10°C/s. It has been found that in the range of 5–0.05°C/s of the applied cooling rate, a diffusion β → α + β transformation is observed. Besides microstructure changes, dilatometric effects were also observed which corroborates the occurrence of phase transformation in the alloy. The obtained results may serve for the interpretation of phase transformations occurring in the Ti13Nb13Zr alloy during aging.

PL

Celem pracy była ocena kinetyki przemian fazowych zachodzących podczas ciągłego chłodzenia z różną szybkością stopu Ti13Nb13Zr z jednofazowego zakresu β. Na podstawie krzywych dylatometrycznych określono temperaturę, w której rozpoczynają się i kończą transformacje dyfuzyjne i niedyfuzyjne. Stwierdzono, że w zakresie zastosowanej szybkości chłodzenia (5–0,05°C/s) obserwuje się transformację dyfuzyjną β → α + β. Oprócz zmian mikrostruktury zaobserwowano również efekty dylatometryczne, które potwierdzają występowanie przemiany fazowej w stopie. Uzyskane wyniki mogą służyć do interpretacji przemian fazowych zachodzących w stopie Ti13Nb13Zr podczas s.