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1

A novel circulating abrasive flow strategy using circular halbach array for magneto-rheological finishing of Ti-6Al-4V

Trinh Nguyen Duy, Tien Dung Hoang, Thoa Pham Thi Thieu, Que Nguyen Van, Quang Kieu Van, Mai Nguyen Trong, Quan Nguyen Ngoc, Nhat Ngo Minh

Journal of Machine Engineering

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2024

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Vol. 24, No. 1

118--134

EN

In the pursuit of advancing the surface machining efficiency of Ti-6Al-4V material through magnetic polishing, this study introduces a new approach methodology. A novel approach integrates Magneto-Rheological Finishing (MRF) into a circulating system, employing a circular Halbach array to ensure a continuous and uniform flow of magnetic abrasives. Employing simulation and theoretical analysis, MRF polishing processes with the fluid dynamics of abrasive (SiO2) and magnetic particles (Fe3O4) during the finishing process of Ti-6Al-4V material using a circulating conveyor designed for the regeneration of abrasive particles. To investigate the impact of magnetic fluid distributions influenced by magnetic fields on the machining process, we meticulously conduct experimental analyses. The findings underscore that diminishing the working distance results in an expanded distribution range of magnetic abrasive fluid on the conveyor belt. Consequently, this induces a noteworthy variation in impact positions on the workpiece surface, leading to an increased exposed area. A pivotal outcome of this study is the observed augmentation in machining quality and efficiency. Remarkably, the surface roughness of the Ti-6Al-4V workpiece undergoes a substantial improvement, diminishing from an initial Ra = 431.1 nm to an impressive Ra = 39.6 nm within a 30-minute timeframe.

2

Wear performance of Ti-6Al-4 V titanium alloy through nano-doped lubricants

Etri Hamza E. L., Singla Anil Kumar, Özdemir Mehmet Tayyip, Korkmaz Mehmet Erdi, Demirsöz Recep, Gupta Munish Kumar, Krolczyk J. B., Ross Nimel Sworna

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e147, 2023

EN

Titanium and its alloys are widely utilized in the biomedical sector, they still exhibit poor tribological properties and low wear resistance when employed against even weaker substances. The poor hardness, instability, high coefficient of friction, low load-carrying capacity, and insufficient resistance to not only abrasive but also adhesive wear are further disadvantages of titanium alloys. The focus of this investigation is on the tribological performance of Ti-6Al-4 V alloy in contact with WC carbide abrasive balls when subjected to nanodoped cooling and lubrication conditions. Tribological experiments were executed on Ti-6Al-4 V flat samples using a ball-on-flat tribometer in dry hybrid graphene/boron nitride combination nanoparticles (MQL, nano-3), nanographene with MQL (nano-1), and boron nitride with MQL (nano-2) conditions. After that, the most significant tribological characteristics were investigated, including volume loss, friction coefficient, wear rate, and micrographic structures. The outcomes also demonstrated that the hybrid nanoparticle situation experienced the least amount of volume loss.

3

Effect of different wire materials on WEDM performance of Bio-compatible material

Pandey Gaurav Kumar, Patel Praveen Bhai, Kumar Abhishek, Niranjan Ramendra Singh, Katiyar Vikas, Chandra A. K

Production Engineering Archives

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2022

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Vol. 28, Iss. 1

50--55

EN

The present experimental investigation aims to analyse the effect of various machining parameters, such as pulse peak current (Ion), pulse on time (Ton), pulse off time (Toff) and spark voltage (SV) on the surface roughness (SR) and material removal rate(MRR) by using continuous traveling of both wire electrode (i.e. brass wire and zinc-coated brass wire). The present work also analyses the effect of types of wires, such as brass wire and zinc-coated brass wire used during machining of Titanium alloy (Ti-6Al-4V) on Surface roughness (SR) and material removal rate (MRR). This work studies the correlation between various response parameter such SR and MRR by using same machining parameter by for both wires.

4

Comparisons between 2D and 3D MPFEM Simulations in Modeling Uniaxial High Velocity Compaction Behaviors of Ti-6Al-4V Powder

Zhou Jian, Xu Hongkun, Zhu Chenyu, Wang Bin, Liu Kun

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

57--65

EN

Multi-particle finite element method (MPFEM) simulation has been proven an efficient approach to study the densification behaviors during powder compaction. However, comprehensive comparisons between 2D and 3D MPFEM models should be made, in order to clarify which dimensional model produces more accurate prediction on the densification behaviors. In this paper, uniaxial high velocity compaction experiments using Ti-6Al-4V powder were performed under different impact energy per unit mass notated as Em. Both 2D and 3D MPFEM simulations on the powder compaction process were implemented under displacement control mode, in order to distinguish the differences. First, the experimental final green density of the compacts increased from 0.839 to 0.951 when Em was increased from 73.5 J/g to 171.5 J/g. Then detailed comparisons between two models were made with respect to the typical densification behaviors, such as the density-strain and density-pressure relations. It was revealed that densification of 2D MPFEM model could be relatively easier than 3D model for our case. Finally, validated by the experimental results, 3D MPFEM model generated more realistic predictions than 2D model, in terms of the final green density’s dependence on both the true strain and Em. The reasons were briefly explained by the discrepancies in both the particles’ degrees of freedom and the initial packing density.

5

Influence of Minimum Quantity Lubrication Using Vegetable-Based Cutting Fluids on Surface Topography and Cutting Forces in Finish Turning of Ti-6Al-4V

Lisowicz Joanna, Habrat Witold, Krupa Krzysztof

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 1

95--103

EN

Titanium alloys are included in the group of difficult-to-cut materials. The use of different methods to reduce the temperature of the machining zone is one of the factors influencing the performance of the machining. The most commonly used method is flood cooling. On the basis of recent research, the conventionally used cutting fluids can cause some health problems for machine operators. Moreover, it was found that they can cause some problems for the environment during storage and disposal. Therefore, in recent years, the aspects of the use of biodegradable fluids and the reduction of the number of metalworking fluids used in machining processes have received much more attention. In this study, the effect of the application of three different vegetable oil-based cutting fluids was evaluated for minimum quantity lubrication (MQL) in finishing the Ti-6Al-4V titanium alloy on surface topography and cutting force components. The same tests were conducted for dry cutting conditions and the results were compared with those after machining with MQL. It was found that the best surface roughness was obtained with the use of the mixture of 50% vegetable oil and 50% diester (1PR20) under all the cutting parameters considered. The biggest differences in the values of the Sa and Sz parameters can be noticed for the lowest feed rate. For the feed rate f = 0.1 mm/rev, the Sa parameter values were approximately 32% and 24% lower for MQL with 1PR20 compared to MQL to LB2000 and dry cutting conditions, respectively. In terms of cutting force components, the lowest values were obtained for the MQL with 1PR20 machining. The values of the main cutting force were about 15% lower compared to the MQL with LB2000 cutting conditions for all the cutting parameters considered.

6

Substituting Ti-64 with AA2099 as material of a commercial aircraft pylon

Khalid Hamza, Gomez-Gallegos A. A.

Advances in Materials Science

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2021

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Vol. 21, nr 2(68)

77--92

EN

The aircraft industry is striving to reduce the weight of aircraft to save fuel and hence reduce total cost. New alloys and composites with properties such as low weight and high strength are continuously developed. Titanium alloys have the best strength-to-weight ratio among metals which makes them very suitable for aircraft applications. Ti-64 is the most common Titanium alloy used in aircraft. AA2099 is a 3rd generation Al-Li alloy and has the lowest density among all Aluminium alloys making it very attractive for aircraft applications. Pylons of commercial aircraft are currently made primarily with Ti-64 and this study focused on the replacement of Ti-64 with AA2099. Loading conditions, operating temperature, corrosion resistance, manufacturability and recyclability of the pylon were analysed of both Ti-64 and AA2099. Three critical scenarios were chosen for the loading conditions of the pylon. These were simulated using finite element analysis first using Ti-64 and then AA2099. From the results, it is evident that using AA2099 as the material of the pylon instead of Ti-64 offered weight savings. The operating temperature, manufacturability and recyclability also showed advantages when using AA2099 whereas corrosion factors favoured Ti-64, since AA2099 was found to be very prone to galvanic corrosion.

7

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.

8

Influence of coefficient of friction on Ti-6Al-4V titanium alloy turning process - FEM analysis

Lisowicz Joanna

Technologia i Automatyzacja Montażu

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2020

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nr 3

22--29

EN

The good properties of Ti-6Al-4V titanium alloy make it widely used, but at the same time, make it difficult to machine. One of the factors which influence the machinability of metal alloys is coefficient of friction, which can be lowered by multiple cooling and lubricating methods. In the present work the influence of coefficient of friction on the turning process of Ti-6Al-4V was analyzed based on the FEM simulations conducted in DEFORM 2D/3D software. It was proven that the coefficient of friction influenced the cutting force and thrust force. It was also shown that the coefficient of friction had a significant impact on the chip compression ratio.

PL

Dobre właściwości stopu tytanu Ti-6Al-4V decydują o jego szerokim zastosowaniu, lecz jednocześnie wpływają na trudnoobrabialność. Jednym z czynników, który wpływa na obrabialność stopów metali jest współczynnik tarcia, którego wartość może być obniżana dzięki zastosowaniu różnych metod chłodzenia i smarowania. W niniejszej pracy przeanalizowano wpływ wartości współczynnika tarcia na przebieg procesu toczenia stopu Ti-6Al-4V, na podstawie symulacji MES przeprowadzonych w programie DEFRORM 2D/3D. Pokazano, iż współczynnik tarcia ma wpływ na wartość siły skrawania i siły odporowej. Uwidoczniono również istotny wpływ wartości współczynnika tarcia na współczynnik spęczenia wióra.

9

Machining of microholes in Ti-6Al-4V by hybrid micro electrical discharge machining to improve process parameters and flushing properties

Mugilan T., Aezhisai Vallavi M. S., Santhosh S., Sugumar D., Christopher Ezhil Singh S.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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Vol. 68, nr 3

565--573

EN

In this research work, the Ti-6Al-4V material was used for the investigation of machining parameters by means of hybrid micro electrical discharge machining to improve the machining process and reduce the negative effects of debris accumulation in the drilled hole. L9 orthogonal array was used in the Taguchi based grey relational analysis to optimize the parameters such as material removal rate and diametrical accuracy of the machining process for Ti-6Al-4V. This work encompasses the design, development, and calibration of the work piece vibration platform and experimental analysis of the process parameters by means of the hybrid micro electrical discharge machining process. The maximum material removal rate and minimum surface roughness was observed at the current value of 2.5 A, pulse on time is 2 μs and pulse off time is 14.5 μs. The maximum material removal rate was observed for the increase in pulse on time with 14.4 μs and 4 A current level. The diametrical accuracy of the microholes was increased while increasing the pulse off time and decreasing the pulse on time. The fluid flow simulation has been conducted to find out the pressure drop and to know the velocity of the flow inside the hole for the effective flushing of the debris during machining.

10

An analysis of fast-changing phenomena in the cutting zone during the turning of a Ti-6AL-4V titanium alloy shaft

Ślusarczyk Łukasz, Franczyk Emilia

Technical Transactions

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2019

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Vol. 116, iss. 8

173--182

EN

This paper presents an experimental method of determining the velocity of chip flow on the rake surface of a cutting insert during the longitudinal turning of Ti-6Al-4V titanium alloy. A Seco CNMG120408-M1 833 carbide cutting insert without a protective coating was used for the purposes of research. In order to record phenomena in the cutting zone, a PHANTOM V5.2 high-speed camera was used and placed above the area of machining. The camera recorded the process at a speed of 3000 fps. Placing the camera near the cutting zone allowed recording the process of chip formation and its flow along the rake face of the insert. Trials of longitudinal turning were performed in accordance with the test plan, where ν🇨 and ƒ were the independent variables. In addition, the tests were performed for two different cutting depths. Processing and analysis of the obtained video sequences were performed with the use of CineViewer 663 and Tracker computer applications. Experimental determination of the velocity of chip flow at the rake face of a cutting insert was conducted by analysing the movement of the characteristic point on the outside side of the chip. Analysis of variance for the obtained results was performed using ANOVA and the regression functions were determined.

PL

W artykule przedstawiono eksperymentalny sposób wyznaczania prędkości spływu wióra po powierzchni natarcia płytki skrawającej podczas toczenia wzdłużnego stopu tytanu Ti-6Al-4V. W ramach badań wykorzystano płytkę skrawającą z węglika spiekanego, bez powłoki ochronnej, Seco CNMG120408 M1 833. Do rejestracji zjawisk w strefie skrawania zastosowano kamerę szybkoklatkową PHANTOM V5.2 umieszczoną nad strefą obróbki. Szybkość rejestracji kamery wynosiła 3000 kl/s. Ustawienie kamery w tym miejscu umożliwiało rejestrację procesu powstawania i spływu wióra po powierzchni natarcia płytki. Próby toczenia wzdłużnego realizowano zgodnie z przyjętym planem badań, gdzie zmiennymi niezależnymi były ν🇨 i ƒ. Dodatkowo próby wykonano dla dwóch różnych głębokości skrawania. Obróbkę i analizę otrzymanych sekwencji wideo przeprowadzono w aplikacjach komputerowych CineViewer 663 oraz Tracker. Eksperymentalne wyznaczenia prędkości spływu wióra na powierzchni natarcia płytki skrawającej realizowano przez analizę ruchu punktu charakterystycznego na zewnętrznej stronie wióra. Dla uzyskanych wyników przeprowadzono analizę wariancji ANOVA i wyznaczono funkcje regresji.

11

Determination of the best microstructure and titanium alloy powders properties using neural network

Duriagina Z. A., Tkachenko R. O., Trostianchyn A. M., Lemishka I. A., Kovalchuk A. M., Kulyk V. V., Kovbasyuk T. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 87, nr 1

25--31

EN

Purpose: Create a software product using a probabilistic neural network (PNN) and database based on experimental research of titanium alloys to definition of the best microstructure and properties of aerospace components. Design/methodology/approach: The database creation process for artificial neural network training was preceded by the investigation of the granulometric composition of the titanium powder alloys, study of microstructure, phase composition and evaluation of micromechanical properties of these alloys by the method of material plasticity estimation in the conditions of hard pyramidal indenters application. A granulometric analysis was done using a special complex of materials science for the images analysis ImageJ. Metallographic investigations of the powder structure morphology were carried out on the scanning electron microscope EVO 40XVP. Specimens for micromechanical testing were obtained by overlaying the titanium alloy powders on the substrate made of the material close to chemical composition. Substrates were prepared by pressing the powder mixture under the load of 400 MPa and following sintering at 1300°C for 1 hour. Overlaying was performed by an electron gun ELA-6 (beam current – 16 mA). Findings: According to the modelling results, a threshold of the PNN accuracy was established to be over 80%. A high level of experimental data reproduction allows us a full or partial replacement of a number of experimental investigations by neural network modelling, noticeably decreasing, in this case, the cost of the material creation possessing the preset properties with preserved quality. It is expected that this software can be used for solving other problems in materials science too. Research limitations/implications: The accuracy of the PNN algorithm depends on the number of input parameters obtained experimentally and forms a database for the training of the system. For our case, the amount of input data is limited. Practical implications: Previously trained system based on the PNN algorithm will reduce the number of experiments that significantly reduce costs and time to study. Originality/value: A software product on the basis of the PNN network was developed. The training sample was built based on a series of laboratory studies granulometric composition of the titanium powder alloys, study of microstructure, phase composition and evaluation of micromechanical properties of powder materials. The proposed approach allows us to determine the best properties of the investigated material for the design of aerospace components.

12

Effect of B4C Reinforcement on the Dry Sliding Wear Behaviour of Ti-6Al-4V/B4C Sintered Composites Using Response Surface Methodology

Ramkumar T., Narayanasamy P., Selvakumar M., Balasundar P.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1179--1200

EN

The present investigation has been made to assess the influence of B4C reinforced with Ti-6Al-4V matrix prepared by powder metallurgy route. High energy ball milling was used to prepare the composites. Cylindrical preforms were prepared using suitable die set assembly. The green preforms were sintered in the muffle furnace at 900°C for 1h. Further the preforms were cooled inside the furnace till the room temperature has attained. SEM with EDS mapping analysis was used to evaluate the morphology and elemental confirmation of the prepared composite. The density and hardness of the samples are determined using Archimedes principle and Rockwell hardness testing machine. The wear resistance of the samples was determined by employing a pin on disc apparatus. The hardness of the composites (Ti-6Al-4V /10B4C) was increased while comparing to the base material (Ti-6Al-4V) which is attributed to the presence of hard ceramic phase. Response Surface Methodology (RSM) five level central composite design approach was accustomed and it minimised the amount of experimental conditions and developed mathematical models among the key process parameters namely wt. % of B4C, applied load and sliding distances to forecast the abrasive response of Specific Wear Rate (SWR) and Coefficient of Friction (CoF). Analysis of variance was used to check the validity of the developed model. The optimum parameters of specific wear rate and coefficient of friction were identified.

13

Inteligentna strategia frezowania naroży ze stopów tytanu

Pałka T.

Stal, Metale & Nowe Technologie

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2017

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nr 5-6

54--56

PL

Frezowanie materiałów trudno skrawalnych wiąże się z wpływem sił skrawania na odkształcenia zarówno narzędzia, jak i przedmiotu obrabianego. Zastosowanie inteligentnych strategii pozwoli na uzyskanie żądanych dokładności wymiarowo-kształtowych. Do materiałów trudno skrawalnych zaliczamy stop Ti6Al4V, stosowany chętnie w medycynie i przemyśle lotniczym.

EN

Milling of difficult-to-machine materials implies the influence of the cutting forces on the deformation of both a tool and a workpiece. The use of intelligent strategies allows to achieve the desired accuracy of the dimension and shapes. Difficult-to-machine materials include Ti6Al4V, willingly used in medicine and the aerospace industry.

14

Effect of Heat Treatment on Microstructure and Impact Toughness of Ti-6Al-4V Manufactured by Selective Laser Melting Process

Lee K.-A., Kim Y.-K., Yu J.-H., Park S.-H., Kim M.-C.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2B

1341--1346

EN

This study manufactured Ti-6Al-4V alloy using one of the powder bed fusion 3D-printing processes, selective laser melting, and investigated the effect of heat treatment (650°C/3hrs) on microstructure and impact toughness of the material. Initial microstructural observation identified prior-β grain along the building direction before and after heat treatment. In addition, the material formed a fully martensite structure before heat treatment, and after heat treatment, α and β phase were formed simultaneously. Charpy impact tests were conducted. The average impact energy measured as 6.0 J before heat treatment, and after heat treatment, the average impact energy increased by approximately 20% to 7.3 J. Fracture surface observation after the impact test showed that both alloys had brittle characteristics on macro levels, but showed ductile fracture characteristics and dimples at micro levels.

15

Wpływ strategii zagłębiania na zużycie narzędzi podczas frezowania stopów tytanu

Pałka T.

Stal, Metale & Nowe Technologie

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2016

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nr 3-4

60--62

PL

Rosnące wymagania co do frezowania materiałów trudno skrawalnych wiążą się z możliwością zwiększenia prędkości skrawania. Wymaga to lepszego zrozumienia wpływu strategii skrawania na wydajność i trwałość narzędzia. Ti-6Al-4V jest najczęściej stosowanym stopem tytanu w przemyśle lotniczym i biomedycznym ze względu na właściwości. W celu zbadania wpływu strategii frezowania na zużycie narzędzia porównano nową strategię frezowania z podejściem konwencjonalnym.

EN

Growing demands for the milling of hard-to-machine materials are connected with the possibility of increasing the cutting speed. This requires a better understanding of the impact of the milling strategy on cutting performance and tool life. Ti-6Al-4V is the most widely used titanium alloy in aerospace and biomedical industries due to its properties. To study the effect of the milling strategy on tool wear, the novel constant engagement milling strategy has been compared with the conventional approach.

16

Ocena stopnia proliferacji komórek osteoblastopodobnych w kontakcie z powierzchniami stopu tytanu po piaskowaniu do różnego stopnia chropowatości

Bociąga D., Olejnik A., Jastrzębski K., Sobczyk-Guzenda A., Paradowska J.

Engineering of Biomaterials

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2016

|

Vol. 19, no. 134

8--17

PL

Tytan i jego stopy są jednymi z najpopularniejszych biomateriałów metalicznych stosowanych w dzisiejszej implantologii. Mimo licznych zalet tych materiałów, wykonane z nich wszczepy często poddaje się dodatkowej obróbce powierzchni, której celem jest polepszenie integracji implantu z otaczającymi go tkankami. Spośród wielu dostępnych technik, jedną z najczęściej wykorzystywanych komercyjnie jest stosunkowo tania i szybka metoda piaskowania, polegająca na wystawianiu danego przedmiotu na kontakt ze strumieniem przyspieszonych cząstek materiału ściernego. Celem tej pracy była analiza wpływu piaskowania ścierniwem o różnej średnicy ziaren na właściwości obrabianej powierzchni elementów na bazie dwóch popularnych stopów tytanu: Ti-6Al-4V i Ti-6Al-7Nb. W celu scharakteryzowania uzyskanych powierzchni przeprowadzono badania ich topografii, składu chemicznego, chropowatości i zwilżalności. Ponadto, aby sprawdzić potencjalną reakcję organizmu na obecność obrobionych w ten sposób elementów dokonano oceny stopnia proliferacji ludzkich komórek kościotwórczych hodowanych w bezpośrednim kontakcie z przygotowanymi powierzchniami. Otrzymane wyniki wykazały wyraźną zależność pomiędzy stopniem chropowatości i składem chemicznym piaskowanych elementów, a zastosowanym do obróbki rodzajem medium ściernego. Badanie zachowania komórek będących w kontakcie z modyfikowanymi próbkami wykazało obniżoną skłonność osteoblastów do przylegania i namnażania na najbardziej chropowatych powierzchniach.

EN

Titanium and its alloys are very popular metallic biomaterials used for medical implants production. Despite numerous advantages of the bulk material, such implants are very often subjected to additional surface treatment in order to improve their integration within the body tissues. Besides many other available techniques, one of the most frequently used in the commercial sector is a fast and economically profitable process of abrasive blasting. It is a method in which a stream of accelerated particles collides with the implant surface what causes changes in the material properties. The following paper presents differences resulting from sandblasting of Ti-6Al-4V and Ti-6Al-7Nb specimens with blasting particles varying in size. In order to characterize the outcome of such the treatment, investigations of surface topography, chemical composition, roughness, and wettability were conducted. Finally, the behaviour of the osteoblast- -like cells adhered to the sandblasted Ti-6Al-4V and Ti-6Al-7Nb surfaces was assessed in order to evaluate potential body response towards the aforementioned materials. The results suggest a strong correlation between surface roughness, its chemistry and the type of blasting medium applied. Evaluation of the cell culture revealed a rapid decrease in cell proliferation rate onto the roughest surfaces.

17

The modelling of ring tests at elevated temperatures for the determination of friction in Ti-6A1-4V forgings

Pollard J. D., Watford A., Jackson M., Wynne B. P.

Computer Methods in Materials Science

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2015

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Vol. 15, No.1

150--155

EN

Ring compression tests and finite element modelling were used to explore the friction conditions present in high temperature Ti-6A1-4V forgings where glass is used as the lubricant. The work explored the use of isothermal and non-isothermal simulations as a means of modelling non-isothermal test conditions. The friction factor is determined by comparison of the deformation of the internal diameter of the experimental compression rings and the simulated compression rings. It was determined that the heat transfer coefficients (HTCs) used in the simulations have a significant result on the friction factor predicted by the simulation results. It was found that it is possible to predict similar deformations through combinations of low HTC/high friction factor and high HTC/low friction factor. Consequently, it is considered critical that the heat transfer conditions for non-isothermal work where there is a high temperature gradient between workpiece and its surroundings be correctly modelled in order to determine the correct friction factor to be used in later simulations.

PL

W pracy badano warunki tarcia w wysokich temperaturach pomiędzy odkuwkami ze stopu Ti-6A1-4V i szkłem, będącym smarem, w próbie spęczania pierścieni przy wykorzystaniu modelowania metodą elementów skończonych. Sprawdzono możliwość zastosowania symulacji zarówno przy zachowaniu warunków izotermicznych, jak i nieizotermicznych, do modelowania nieizotermicznych warunków prób doświadczalnych. Czynnik tarcia oszacowano porównując zmiany wewnętrznej średnicy pierścienia w eksperymencie i symulacji numerycznej. W trakcie badań zaobserwowano, że wartość współczynnika wymiany ciepła (HTCs) przyjęta w modelowaniu ma istotny wpływ na wyznaczony w oparciu o symulacje czynnik tarcia. Zauważono, że możliwe jest otrzymanie zbliżonych wyników dla kombinacji: mały HTCs/duża wartość czynnika tarcia oraz duża wartość HTCs/mały czynnik tarcia. W związku z powyszym stwierdzono, że warunki wymiany ciepła w procesie nieizotermicznym, charakteryzującym się znacznym gradientem temperatury pomiędzy próbką a otoczeniem, powinny być prawidłowo uwzględnione dla poprawnego wyznaczenia czynnika tarcia stosowanego w kolejnych symulacjach.

18

Self-Consolidation Mechanism Of Porous Ti-6Al-4V Implant Prototypes Produced By Electro-Discharge-Sintering Of Spherical Ti-6Al-4V Powders

Lee W. H., Jo Y. J., Kim Y. H., Jo Y. H., Seong J. G., Van Tyne C. J., Chang S. Y.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1185--1189

EN

Electro-Discharge-Sintering (EDS) was employed to fabricate Ti-6Al-4V porous implant prototypes from atomized powders (100 – 150 μm), that were subjected to discharges of 0.75 to 2.0 kJ/0.7g-powder from 150, 300, and 450 μF capacitors. Both fully porous and porous-surfaced Ti-6Al-4V compacts with various solid core sizes were self-consolidated in less than 86 – 155 μsec. It is known that EDS can simultaneously produce the pinch pressure to squeeze and deform powder particles and the heat to weld them together. The formation of a solid core in these prototypes depends on the amounts of both the pinch pressure and heat generated during a discharge. The size of the solid core and the thickness of the porous layer can be successfully controlled by manipulating the discharge conditions such as input energy and capacitance.

19

Influence of thermo hydrogen treatment on hot deformation behaviour and microstructural evolution of Ti-6Al-4V alloy

Losertova M., Stamborska M., Schindler I.

Archives of Materials Science and Engineering

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2014

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Vol. 66, nr 2

62--66

EN

Purpose: The present work compares the hot deformation behaviour at 800°C and microstructure evolution after the isothermal compression test of hydrogen containing specimens with that of non-hydrogenated Ti-6Al-4V alloy. Design/methodology/approach: Specimens in hydrogenated and non-hydrogenated state were tested by means of isothermal compression at 800°C and strain rate of 0.005 s-1 on a Gleeble-3800 machine. Thermal hydrogen treatment of specimens in flowing hydrogen consisted of annealing 1 h at 600°C, 0.5 h at 850°C and aging 4 h at 590°C. Findings: Hydrogen contents in specimens at conditions as-received, heat treated in argon and in hydrogen and after isothermal compression test were measured using an analyzer LECO RH600. Thermal hydrogen treatment resulted in amount of hydrogen as high as 0.98 wt. %. After isothermal compression test the hydrogen content of 0.46 wt. % was retained in the specimens. Practical implications: The THT technology allows improving of fatigue and strength properties through microstructure refinement. Reversible hydrogen alloying provides decreasing flow stress and increasing hot workability of titanium alloys at lowers temperatures. Originality/value: The special heat treatment technology of Ti-based alloys, so-called the thermo hydrogen treatment (THT), employs the reversible reaction of hydrogen with titanium in order to modify phase compositions, evolution of metastable phases and kinetics of phase transformations in titanium alloys.

20

Właściwości stopu Ti-6Al-4V po modyfikacji powierzchni

Adamek G., Jakubowicz J.

Engineering of Biomaterials

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2013

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Vol. 16, no. 120

35--40

PL

W pracy badano właściwości porowatego stopu Ti-6Al-4V istotne z punktu widzenia zastosowań na implanty tkanek twardych. Stop wytworzono za pomocą procesu mechanicznej syntezy, prasowania i spiekania. Modyfikację powierzchni prowadzono dwuetapowo: pierwszym było elektrochemiczne trawienie w 1M H3PO4 + 2% HF w 10 V przez 30 min, a drugim osadzanie ceramiki fosforanowo wapniowej (Ca-P) z wodnego roztworu 0,042M Ca(NO3)2 + 0,025M (NH4)2HPO4 + 0,1M HCl. Jony wapnia i fosforanowe osadzają się w głębi porów, co polepsza wytrzymałość połączenia ceramicznej powłoki z metalicznym podłożem. Wytrzymałość była o ponad 50% większa dla porowatego stopu niż dla litego odpowiednika. Odporność korozyjną badano w roztworze Hanka symulującym środowisko płynów ustrojowych (SBF). Po osadzaniu powłoki Ca-P zaobserwowano niewielką poprawę gęstości prądu korozyjnego w stosunku do próbki polerownej. Zbadano również biozgodność stopu po modyfikacji powierzchni w testach in vitro. Powierzchnia po elektrochemicznej modyfikacji wykazuje dobrą biozgodność, a powłoka Ca-P wspomaga wzrost i proliferację osteoblastów. Ze względu na porowatość, stosunkowo dobrą wytrzymałość połączenia i biokompatybilność powierzchni stop Ti-6Al-4Vpo elektrochemicznej modyfikacji wydaje się być dobrym materiałem na implanty tkanek twardych.

EN

Properties of a porous Ti-6Al-4V alloy, important in hard tissue implants applications, were investigated. The alloy was prepared by mechanical alloying followed by pressing, sintering and subsequent anodic electrochemical etching in 1M H3PO4 + 2% HF elec¬trolyte at 10 V for 30 min and bioactive ceramic Ca-P layer deposition, using a mixture of 0.042M Ca(NO3)2 + 0.025M (NH4)2HPO4 + 0.1M HCl dissolved in distilled water. The Ca2+ and PO43- ions penetrate the pores preferentially inside, which results in improved bonding of the bioceramic layer to the metallic substrate. The bond strength obtained by a tensile test shows more than 50% higher strength to the porous Ti-6Al-4V substrate than to the bulk material. The corrosion resistance of the alloys was investigated in Hank's Balanced Salt Solution (HBSS) which is simulated body fluid (SBF). We observed slight improvement in corrosion current density after etching and additional Ca-P deposition compared to mechanically polished samples. The biocompatibility of the Ti-6Al-4V alloy with a porous Ca-P layer was investigated. We showed that the rough, electrochemically biofunctionalized sur¬face supported osteoblast cell growth and proliferation. Due to rough morphology, relatively strong bonding to the metallic substrate and in vitro biocompatibility the electrochemically modified surface of the ultrafine grained Ti-6Al-4V is promising for hard tissue implant applications.