Ipek Akin

Ipek Akin
Istanbul Technical University · Department of Metallurgical and Materials Engineering

Associate Professor

About

48
Publications
9,524
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477
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March 2017 - March 2021
Istanbul Technical University
Position
  • Professor (Associate)

Publications

Publications (48)
Article
Full-text available
Potassium sodium niobate (KNN) is a well known piezoelectric material and a developing candidate for replacing lead based high performance piezoceramics due to limitations of hazardous materials in electronic devices. Lithium substitution in KNN structure leads a crystal transition from orthorhombic to tetragonal symmetry at room temperature and en...
Article
In this study, the effect of GNP concentration on the mechanical properties of spark plasma sintered TiB2 and NbB2 ceramics was investigated. GNP reinforced TiB2 and NbB2 specimens were aimed to produce with nearly full densification. Herein, SEM investigations, Raman analysis, and oxidation behavior of the samples were reported. GNP addition into...
Article
The influence of two different spark plasma sintering (SPS)‐based processing routes (i.e., reactive SPS (RSPS) and non‐reactive SPS) on the properties of TaB2‐TaC composites was investigated. Ta2O5 and B4C powders were used as starting materials in the RSPS method, and synthesis and densification of TaB2‐TaC composites were accomplished in a facile...
Article
Bulk (ZrxNb1-x)B2 solid solution systems with x ranging from 0 to 1 with intervals of 0.25, were consolidated by spark plasma sintering (SPS) at 1850 °C under 50 MPa with a holding time of 5 min. In addition, 1 vol% graphene nanoplatelets (GNPs) and 1 vol% hexagonal boron nitride (h-BN) were added to (Zr,Nb)B2 solid solutions to investigate their e...
Preprint
Full-text available
The influence of two different spark plasma sintering-based processing routes (i.e., reactive SPS (RSPS) and non-reactive SPS) on the properties of TaB 2 -TaC composites was investigated. Ta 2 O 5 and B 4 C powders were used as starting materials in the RSPS method, and synthesis and densification of TaB 2 -TaC composites were accomplished in a fac...
Article
The aim of this study is to produce highly dense Si3N4 based composites with good mechanical properties and bioactivity. Si3N4 ceramics without using sintering aids, Si3N4-HA and Si3N4-HAGNP based composites have been produced by spark plasma sintering (SPS) at temperatures of 1525–1550°C. The effect of reinforcement type and content on the densifi...
Article
Full-text available
The aim of this study is to produce highly dense Si3N4 based composites with good mechanical properties and bioactivity. Si3N4 ceramics without using sintering aids, Si3N4-HA and Si3N4-HA-GNP based composites have been produced by spark plasma sintering (SPS) at temperatures of 1525–1550°C. The effect of reinforcement type and content on the densif...
Article
This research focuses on the production and characterization of (Zr,Ti)B2 solid solution systems. The purpose of this study is to understand how solid solution formation influences the structure, mechanical properties, and oxidation resistance of ZrB2 and TiB2. For this, herein, monolithic ZrB2, TiB2, and (ZrxTi1-x)B2 solid solution systems (x = 0....
Article
Full-text available
Monolithic NbB2, NbB2-SiC, and NbB2-SiC-GNP samples were produced by spark plasma sintering (SPS), and the effects of additives on the mechanical and thermal properties, microstructures, and oxidation behavior of the samples were investigated. The addition of SiC up to 30 vol% decreased the Vickers hardness of the binary composites due to microcrac...
Article
TZM alloy (molybdenum alloy containing 0.5–0.8 wt% titanium, 0.08–0.1 wt% zirconium and 0.016–0.02 wt% carbon) provides an advantage at elevated temperatures compared to pure molybdenum due to having a superior recrystallization temperature by the formation of TiC and ZrC in the molybdenum matrix. In this study, besides the formation of carbides, T...
Article
Graphene nanoplatelets were incorporated into (20-x)TiC-80ZrC(vol%) composite powder with x = 0, 0.5, 1, 2, 3, 6 and 9 vol% contents. The resulting powder mixture were sintered by spark plasma sintering (SPS) at 1700 °C under 40 MPa with 300 s holding time. The prepared composites were then characterized in terms of their densification, microstruct...
Article
Monolithic TiB2, TiB2-SiC, and graphene nanoplatelet (GNP)-containing TiB2–SiC-GNP composites were prepared by spark plasma sintering (SPS). The Vickers hardness and thermal conductivity values of the TiB2-SiC composites decreased with increasing SiC addition. However, SiC addition increased the fracture toughness and oxidation resistance relative...
Chapter
This chapter will provide a detailed overview of the processing techniques and properties of bioceramics, with special emphasis on nearly inert ceramics like alumina-based composites and bioactive ceramics like hydroxyapatite-based composites and machinable glass ceramics. The chapter mainly covers the types of bioceramic implant–tissue attachments...
Article
Full-text available
The addition of multi-wall carbon nanotubes (MWCNTs) to ceramic matrices can be utilized for special applications such as implant materials. In this study, zirconia toughened alumina (ZTA) composites having 10, 20 and 30 vol % yttria stabilized zirconia (YSZ) with additions of 0.5, 1, and 2 wt % MWCNTs were prepared by spark plasma sintering (SPS)...
Chapter
Full-text available
This entry will provide a detailed overview of the processing techniques and properties of bioceramics, with special emphasis on nearly inert ceramics like alumina-based composites and bioactive ceramics like hydroxyapatite-based composites and machinable glass ceramics. The entry mainly covers the types of bioceramic implant–tissue attachments, po...
Article
Al2O3 and Al2O3–YSZ composites containing 3 and 5 wt.% TiO2 were prepared by spark plasma sintering at temperatures of 1350–1400 °C for 300 s under a pressure of 40MPa. The grain growth of aluminawas suppressed by the addition of YSZ. Al2O3–YSZ composites showed higher hardness than monolithic Al2O3. There was not a considerable difference in hardn...
Article
The electrical properties of Sr1-3xLa2xTiO3 ceramics (x = 0.05, LST) change dramatically with sintering temperature and atmosphere. Ceramics sintered at 1200 degrees C in both O-2 and N-2 exhibit near intrinsic band-type conduction with bulk conductivity similar to 10(-7) S cm(-1) at 500 degrees C and activation energy for conduction, E-a of simila...
Article
Full-text available
In the present study, new bioceramic with the composition 75%Al2O3-25%3Y-TZP was investigated in vitro and in vivo with the aim of evaluating the osseointegration improvement by surface modification upon SnF2 and NaBF4 treatment. In vitro tests were carried out in human fibroblasts culture, whereas in vivo tests were performed using an animal model...
Article
Full-text available
The aim of this study is to investigate the adherence properties of acrylic cement based on PMMA to alumina ceramics. These ceramics are suitable for orthopedic and dental applications, as bioinert components in prosthetic surgery. The surface of alumina specimens were subjected to a special treatment based on acid etched followed by two dierent uo...
Article
Full-text available
The aim of our study is to compare the structural and biological tolerance of novel Al2O3/3Y-TZP composites with ceria respectively titania addition (5 wt%). Scanning electron microscopy, X-ray diffraction, infrared spectroscopy and XPS results are reported for structural characteristics and surface modifications upon different fluoride treatments....
Article
Full-text available
The aim of this study was to prepare and to characterize the structure of Al2O3–3YSZ composites with 5% TiO2 addition as well as the surface modification upon treatments with SnF2 and NaBF4, respectively. SEM micrographs showed the controlled densification of the composites as an effect of 3YSZ and TiO2 addition to alumina matrix. By FTIR and XRD,...
Article
Full-text available
Series of Atmospheric Plasma Spray Coatings were made on titanium substrates based on a Full Factorial Design. Three parameters (number of pass of the bond coat, amount of TiO2 into coating powder precursor and the spray distance) with three levels were selected to investigate their effects on the bonding strength and bioactivity. The coatings were...
Article
B4C-SiC composites were produced using spark plasma sintering (SPS) both reactively from B4C-SiO2-C starting powders and directly from B4C-SiC at 1700 and 1750 degrees C under a pressure of 40 MPa. Densification, microstructure and mechanical properties of B4C-SiC composites were investigated. 98.8% relative density was obtained with the addition o...
Conference Paper
Full-text available
INTRODUCTION: Al 2 O 3 , ZrO 2 and TiO 2 have been considered as bioinert ceramics since they cannot induce apatite formation in SBF. They do however support bone cell attachment, proliferation and differentiation [1]. The ideal ceramic is a high performance biocomposite that combines the excellent material properties of alumina in terms of chemica...
Conference Paper
Full-text available
INTRODUCTION: The alumina-zirconia composites attracted a special attention for orthopaedic applications [1]. Their structure is highly dependent on the synthesis method and in the framework of the same method it depends on processing conditions like synthesis temperature, and parameters of the applied heat treatments. Morphological and structural...
Article
Zirconium carbide (ZrC) is an important structural ceramic due to its high melting temperature, excellent chemical resistance, high electrical conductivity and good mechanical properties. This combination of properties makes it potentially useful in application of cutting tools, high temperature crucibles and thermal protection components. However,...
Article
Full-text available
ZrB2-ZrC-SiC composites were prepared by spark plasma sintering (SPS) at temperatures of 1750 degrees C for 300 s under a pressure of 40MPa. Densification, microstructural, mechanical properties and oxidation behavior of the composites were investigated. Fully dense ZrB2-ZrC-SiC composites with a relative density of more than 99% were obtained at 1...
Article
Full-text available
Hydroxyapatite (HA) ceramics are used extensively in different medical applications, such as biomaterial for repair or replacement of bone tissues since it resembles mineral component of bone and teeth. However, HA exhibits low fracture toughness due to its lack of strength and brittleness, thereby providing an obstacle to its application in implan...
Article
Alumina (Al2O3) and alumina–yttria stabilized zirconia (YSZ) composites containing 3 and 5mass% ceria (CeO2) were prepared by spark plasma sintering (SPS) at temperatures of 1350–1400°C for 300s under a pressure of 40MPa. Densification, microstructure and mechanical properties of the Al2O3 based composites were investigated. Fully dense composites...
Article
Full-text available
Polymer-ceramic composites based on polymethyl methacrylate are widely used in orthopaedics as suture materials and fixation devices due to their biocompatibility and ability to support bony growth (osteoconductive) and also bone bioactive (to form a calcium phosphate layer on its surface). The aim of this study is to compare the microstructure, bi...
Article
Full-text available
The aim of our study is the characterization and comparison of structural properties of two novel alumina/zirconia ceramics prepared by Spark Plasma Sintering and biocompatibility evaluation by using an animal model (Wistar rats). SEM, XRD and FTIR spectroscopic results are reported for structural characteristics. In vivo tests demonstrated the bio...
Article
Full-text available
Complementary spectroscopic methods such as FTIR, FT Raman and XPS are applied in this work in order to investigate the surface of acrylic cements after electrolytic deposition of collagen. As an alternative of antibiotic, silver oxide was incorporated in the polymethyl metacrylate (PMMA) matrix and structural properties are discussed by comparing...
Article
Full-text available
Orthopedic acrylic cements have to fulfill several medical requirements, such as: low values of maximum cure temperature (to avoid thermal necrosis of the bone tissue, during the setting of the cement), moderate sitting time (so that cement does not cure too fast or too slow), high values of compressive strength (allowing the cured cement mantle to...
Article
In this study, monolithic Al₂O₃ and Al₂O₃/3Y-TZP (90–10 vol%) and Al₂O₃/3Y-TZP with 5wt% TiO₂ composites were prepared by spark plasma sintering (SPS) at temperatures of 1350, 1460°C and 1300°C for 300 s under a pressure of 40MPa, respectively. Shrinkage of the specimens during SPS process was continuously monitored. Densities of the composites wer...
Article
Full-text available
ZrB2 and ZrB2-SiC composites containing 40 and 60 mass% SiC were prepared by spark plasma sintering (SPS) at temperatures of 1810 and 1770°C for 300 s under a pressure of 40 MPa. Oxidation behavior of these samples was characterized by exposing them to 1400, 1500, and 1600°C in an ambient atmosphere for 180 min, and by measuring the weight gains of...
Article
Machinable bioactive glass-ceramics containing microcrystalline phases of mica and apatite can be considered as new materials for bone implants and substitutes in human body. Such a glass-ceramic has a better machinability than others due to the large amount of layered mica phase which is oriented randomly and distributed uniformly in glass matrix....
Article
Full-text available
ZrB2–SiC composites were prepared by spark plasma sintering (SPS) at temperatures of 1800–2100 °C for 180–300 s under a pressure of 20 MPa and at higher temperatures of above 2100 °C without a holding time under 10 MPa. Densification, microstructure and mechanical properties of ZrB2–SiC composites were investigated. Fully dense ZrB2–SiC composites...
Article
Full-text available
The bone-bonding ability of a glass ceramic can be evaluated by using simulated body fluid (SBF). Furthermore, rat primary osteoblast cell culture is effective in collecting preliminary information for potential application of any material of organic or inorganic origin. In this study, the effect of CeO2 addition on crystallization behavior and bio...
Article
Potassium sodium niobate (KNN) is a well known piezoelectric material and a developing candidate for replacing lead based high performance piezoceramics due to limitations of hazardous materials in electronic devices. Lithium substitution in KNN structure leads a crystal transition from orthorhombic to tetragonal symmetry at room temperature and en...
Article
The aim of this study is to investigate the crystallization behavior and in-vitro bioactivity character of glass ceramics having 3:7 weight ratio of fluorapatite (Ca10(PO4)6F2) to potassium mica (K2Mg3AlSi3O10F2) as a function of cerium oxide addition, and compare the morphology of hydroxycarbonate apatite (HCA) layer formation depending on cerium...
Article
In this study, the effect of TiO2 addition as a nucleating agent on the crystallization and machinability of potassium mica and fluorapatite base glass ceramics were investigated. Glass compositions were prepared and casted at predetermined temperatures. Differential thermal analysis and XRD methods were applied to characterize phase precipitation...
Article
The aim of this study is to find out the crystallization behaviour and in-vitro bioactivity character of machinable glass ceramics having different ratios of Na/K mica and apatite phases, to ascertain the best machinable composition. In order to investigate the bioactivity behavior of the samples the simulated body fluid (SBF) was prepared. Samples...
Article
Machinable glass ceramics are materials produced by the similar production methods of melting and casting that all glass ceramics with controlled nucleation and crystallization. In the first stage of this study, glass compositions containing different ratios of potassium mica and cordierite have been prepared, mixed and casted at proper temperature...
Conference Paper
In this study; in-vitro bioactivity characterization of machinable glass-ceramics having 85 wt% sodium mica (NaMg3AlSi3O10F2) and 15 wt% fluoroapatite has been carried out. Two different heat treatment procedures are applied to the machinable glass-ceramics. The first one is nucleation at 610 degrees C for 2 hours and crystallization at 1000 degree...
Article
The purpose of this study is to investigate the crystallization behavior and in-vitro bioactivity character of glass ceramics having 3:7 weight ratio of flourapatite (Ca5(PO4)3F) to potassium mica (K2Mg3AlSi3O10F2) as a function of titania addition, and compare the morphology of hydroxycarbonateapatite (HCA) layer formation depending on titania add...

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Projects

Projects (5)
Project
This project covers the spark plasma sintering (SPS) and characterization (densification, phase and microstructure, mechanical properties, oxidation behavior, etc.) of 3 sample groups: (Zr,Ti)B2, (Zr,Nb)B2, (Ti,Nb)B2 solid solutions.
Archived project
Archived project
To produce AlON ceramics which have high transparency and mechanical properties by using different additive mixtures of MgO,La2O3 and Y2O3 in SPS via reactive sintering of Al2O3 and AlN starting powders at lower temperature and shorter time comparing with conventional methods.