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Bakır kaplı çelik borular, özellikle otomobil fren sistemleri olmak üzere birçok ürünün hidrolik sistemlerinin temel bileşenleridir. Otomotiv endüstrisinde kullanılmak üzere üretilen bakır kaplı çelik boruların sahip olmaları gereken mekanik özellikler kabul kriterleri ile belirlenmiştir. Ancak bu mekanik özelliklerin yanı sıra üretim aşamasında havşa açma gibi prosesler için boruların şekillendirilme kabiliyetleri (süneklilikleri) de oldukça önemlidir. Bu çalışmada, ısıl işlem ile bakır kaplı çelik boruların süneklilik değerlerinin iyileştirilmesi amaçlanmıştır. Bu bağlamda, ısıl işlemsiz bakır kaplı çelik borunun ve 6 farklı ısıl işlem parametresi ile elde edilmiş bakır kaplı çelik boruların mikroyapısal ve mekanik özellikleri karşılaştırmalı olarak incelenmiştir. Optimum tavlama ısıl işlem parametresi ile 450 °C ve 120 dk. ’da 118,7±0,6 HV Vickers sertlik, 315,7±0,6 MPa çekme mukavemeti, 262,7±10,3 MPa akma mukavemeti, 36,9±0,9% kopma uzaması ve 1260 Bar patlatma dayanım değerleri elde edilmiştir. Dolayısıyla, ısıl işlem ile bakır kaplı çelik borunun sırasıyla, sertlik, çekme mukavemeti, akma mukavemeti, patlatma dayanımı değerlerinde yaklaşık %7,05 düşüş, %8,84 düşüş, %6,49 artış, %16,00 düşüş görülürken kopma uzamasında ise yaklaşık %55,04 artış gerçekleştiği elde edilen sonuçlardan görülmüştür.

In this study, hot rolling is properly performed on pure magnesium and two of Zn, Ca and Mn containing magnesium alloys. Biodegradability and mechanical properties are investigated comparatively in their rolled state. While the average grain sizes of the two alloys were close to each other, it was observed that the Mg-1.01Zn-1.63Ca-0.30Mn alloy had higher hardness (61.5 ± 0.2 HV) at hot rolled state. The lowest corrosion rate in electrochemical corrosion test on Mg-1.07Zn-0.21Ca-0.31Mn alloy is observed to be 1.772 mm/yr. As for the immersion corrosion test on the same alloy, the lowest corrosion rate is detected to be 0.054 mm/yr. Moreover, Mg-1.07Zn-0.21Ca-0.31Mn alloy has the highest tensile strength. Based on the results, it is ascertained that hot-rolled Mg-1.07Zn-0.21Ca-0.31Mn alloy possesses a better biodegradability and mechanical properties compared to hot rolled commercially unalloyed Mg and 1.01Zn-1.63Ca-0.30Mn alloy.

This study investigated the microstructures, mechanical performances, corrosion resistances, and in vitro studies of porous Ti-xNb-10Zr (x: 10 and 20; at. %) alloys. The alloys were fabricated by powder metallurgy with two categories of porosities, i.e., 21–25% and 50–56%, respectively. The space holder technique was employed to generate the high porosities. Microstructural analysis was performed by using various methods including scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and x-ray diffraction. Corrosion resistance was assessed via electrochemical polarisation tests, while mechanical behavior was determined by uniaxial compressive tests. In vitro studies, such as cell viability and proliferation, adhesion potential, and genotoxicity, were examined by performing an MTT assay, fibronectin adsorption, and plasmid-DNA interaction assay. Experimental results showed that the alloys had a dual-phase microstructure composed of finely dispersed acicular hcp α-Ti needles in the bcc β-Ti matrix. The ultimate compressive strength ranged from 1019 MPa to 767 MPa for alloys with 21–25% porosities and from 173 MPa to 78 MPa for alloys with 50–56% porosities. Noted that adding a space holder agent played a more critical role in the mechanical behaviors of the alloys compared to adding niobium. The pores were largely open and exhibited irregular shapes, with uniform size distribution, allowing for cell ingrowth. Histological analysis showed that the alloys studied met the biocompatibility criteria required for orthopaedic biomaterial use.

Bu çalışmada, haddeleme işlemi ile AISI 304 östenitik paslanmaz çelik ve AISI 430 ferritik paslanmaz çelik sacları araya ticari saflıkta 1050 alüminyum levha konularak lamine kompozit üretilmiştir. Üretim sonrası farklı sıcaklık ve sürede ısıl işlem uygulanmış kompozit plakaların ara yüzey bağ mukavemeti, mikroyapısı ve mekanik özellikleri incelenmiştir. Kompozitlerin mekanik özellikleri çekme testi, mikro sertlik ölçümü, sıyırma testi ile belirlenmiş, taramalı elektron mikroskobu (SEM) ve enerji dağılımı spektroskopisi (EDS) ile karakterize edilmiştir. Uygulanan ısıl işlem parametreleri arasında yüksek mekanik özellik (434,95MPa) ve süneklik (%27,16) sağlaması yönünden ve işlem kolaylığı bakımından 450˚C-12 h uygun görülmüştür. 550˚C’de 12 h yapılan ısıl işlem sonrasında ise katmanlar arasındaki bağ kuvvetinin sıfıra yakın bir değere düştüğü belirlenmiştir.

In this study, Mg-3Al-1Sn-1Nd-Mn alloy was produced by low-pressure die casting method and homogenization heat treated (HHT) at 400 °C for 16 hrs. Microstructural characterization of the alloy was done by XRF, XRD, LOM and SEM–EDS analyses. The microstructure of the alloy was composed of α-Mg, Al2Nd and Al11Nd3 phases. Hot rolling was applied to the HHT alloy at two different speeds 13.78 rpm [low speed rolling (LSR)] and 26.96 rpm [high-speed rolling (HSR)] at 350 °C. Microstructural changes were also carried out by LOM and SEM analyses. Mechanical properties (hardness and tensile properties) and wear performances of HHT, LSR and HSR samples were compared. SEM fractography was conducted on tension test samples to visualize the deformation and fracture behaviors. Also, worn surfaces of samples were investigated by SEM–EDS analysis. Abrasive, oxidation and delamination mechanisms were observed for worn surfaces of samples. To sum up, the mechanical properties of the HSR sample were higher compared to the HHT and LSR samples, and the wear rate was lower than HHT and LSR samples.

In this study, four different Mg-Zn-Ca-Mn alloys were produced using gravity die casting method. Mn content was kept constant in all alloys, while Zn and Ca were added in two different ratios. Homogenization heat treatment was applied to all cast alloys and a specimen from each homogenized alloy was hot rolled. Microstructure, mechanical properties, and corrosion behavior of the homogenized and hot rolled alloys were investigated as comparatively. Following results were obtained; grain size decreased significantly with increasing Zn content, Zn promoted Ca2Mg6Zn3 phase formation, corrosion resistance increased with increasing Zn/Ca atomic ratio, hot rolling resulted in much higher tensile strength but much lower ductility and toughness. Among the homogenized and hot rolled alloys, ZXM300-h alloy (hot rolled ZXM300 alloy) with its 146 ± 2.5 MPa yield strength, 229 ± 3.7 MPa tensile strength,% 1.6 ± 0.1 elongation and 0.029 mm/yr. immersion corrosion rate exhibited the best mechanical properties and corrosion resistance to be used as a biodegradable alloy such as fracture bone plate material.

In this study, as-cast Mg, ZXM100 (1.07Zn–0.21Ca–0.31Mn) and ZXM120 (1.01Zn–1.63Ca–0.30Mn) alloys were produced by gravity die casting method, and microstructure, phase analysis, corrosion and mechanical properties of the alloys were investigated comparatively in order to develop degradable Mg-based biomaterials with improved properties. It is observed that Ca2Mg6Zn3 phase is expected to be present in ZXM100 (1.07Zn–0.21Ca–0.31Mn) alloy totally dissolved in the α-Mg matrix after homogenization heat treatment. However, Mg2Ca phase is expected to be present in ZXM100 (1.07Zn–0.21Ca–0.31Mn) alloy partially dissolved in the α-Mg matrix. Results showed that ZXM100 alloy has a much more homogeneous structure, a better performance, higher corrosion resistance and mechanical properties than those of as-cast Mg and ZXM120 alloy. ZXM100 (0.099 mm/year) alloy has a three times slower corrosion rate than ZXM120 (0.294 mm/year) alloy. It is found that the ZXM100 alloy has closer values to the desired corrosion rate and mechanical properties as a biodegradable implant material.

Reference materials (RMs) are one of the basic materials used by the laboratories to prove the reliability of their test results. In this research, preliminary studies have been carried out to develop RM to use in tensile tests according to ISO 6892-1. For this purpose, bone shape flat specimens were prepared from EN 10130:2006 quality 1 mm thick sheet steel related to the given standard. Homogeneity tests and inter-laboratory comparison tests were performed for calculation of measurement uncertainty and value assignment of proposed RM. Results were compared with commercial certified reference materials (CRMs). It was found that relative uncertainty values of the proposed RM were coherent with commercial CRMs. Therefore, these produced RM can be used in quality control studies for laboratories, also by the production route proposed in this study, every laboratory can be produced RM related to their needs., Referans malzemeler (RM'ler), laboratuvarların test sonuçlarının güvenilirliğini kanıtlamak için kullandıkları temel malzemelerden biridir. Bu araştırmada, ISO 6892-1'e göre çekme testlerinde kullanılmak üzere RM'nin geliştirilmesi için ön çalışmalar yapılmıştır. Bu amaçla, verilen standarda uygun EN 10130: 2006 kalite 1 mm kalınlığında çelik sacdan kemik şeklinde yassı numuneler hazırlanmıştır. Önerilen RM'nin ölçüm belirsizliği ve değer atamasının hesaplanması için homojenlik testleri ve laboratuvarlar arası karşılaştırma testleri yapılmıştır. Sonuçlar ticari sertifikalı referans malzemelerle (CRM'ler) karşılaştırıldı. Önerilen RM'nin göreceli belirsizlik değerlerinin ticari CRM'ler ile uyumlu olduğu bulundu. Bu nedenle üretilen bu RM'ler laboratuvarlar için kalite kontrol çalışmalarında kullanılabilir, ayrıca bu çalışmada önerilen üretim yolu ile her laboratuvar kendi ihtiyaçlarına göre RM üretebilir.

In this study, Mg was alloyed with Zn and Ca to produce six different Mg–Zn–Ca alloys (designated as ZX alloys) by the gravity die casting method. Zn contents of the alloys were 1 wt., 3 wt., and 5 wt.% and Ca contents of the alloys were 0.2 wt. and 1.8 wt.%. Homogenization heat treatment was applied to all cast alloys. After that, a part of each homogenization heat-treated alloys was hot-rolled. Microstructure, mechanical properties, electrochemical and immersion corrosion behaviors at simulated physiological conditions of the heat-treated and hot-rolled alloys were compared. Increasing the amount of alloying elements (Zn and Ca) in Mg reduces grain size and improves the hardness. It was seen that the microstructure consisted of α-Mg as a matrix phase and intermetallic phases: Mg2Ca phase for the alloy having Zn/Ca = 0.37 (ZX12) and Ca2Mg6Zn3 phase for the other alloys. When the mechanical properties and corrosion rates of homogenized and hot-rolled alloys were compared, it was seen that hot-rolled ZX10-h (Mg-0.94Zn-0.16Ca) alloy can be considered as a fracture bone fixation plate material with its acceptable properties: 121 ± 2.1 MPa yield strength, 226 ± 3.7 MPa tensile strength, % 4.1 ± 0.2 elongation, and 0.062 mm/year immersion corrosion rate.

In this study; Hybrid composites containing different proportions of TiB2 and graphene were produced using the pressure infiltration method. Inert SF6 gas is used to prevent oxidation in the productions. While 8 bar infiltration pressure was provided by argon gas, the infiltration temperature was chosen as 800°C. The corrosion behaviors of the compos-ite materials were examined. Corrosion resistance was determined by potentiodynamic and immersion corrosion testing in 3.5% NaCl solution. In addition, SEM examinations were conducted to understand the corrosion mechanisms. At the end of the measurements, the highest porosity was measured as %4,7 in composite containing 1% graphene compared to pure matrix and composite containing only TiB2. The added reinforcement (TiB2 and Graphene) elements cause decreases in corrosion resistance. The highest corrosion resist-ance was achieved in AZ91 alloys.

In this study, Mg was alloyed with Zn and Ca to produce six different Mg-Zn-Ca alloys (designated as ZX alloys) by the gravity die casting method. Zn contents of the alloys were 1 wt., 3 wt., and 5 wt.% and Ca contents of the alloys were 0.2 wt. and 1.8 wt.%. Homogenization heat treatment was applied to all cast alloys. After that, a part of each homogenization heat-treated alloys was hot-rolled. Microstructure, mechanical properties, electrochemical and immersion corrosion behaviors at simulated physiological conditions of the heat-treated and hot-rolled alloys were compared. Increasing the amount of alloying elements (Zn and Ca) in Mg reduces grain size and improves the hardness. It was seen that the microstructure consisted of α-Mg as a matrix phase and intermetallic phases: Mg

In this work, phase selection, microstructure and mechanical properties of Mg-Al-Ca-Mn alloys with three different Ca/Al ratios (0.58, 0.79 and 0.91) were studied. The Mn content of the alloys was kept constant at ∼0.30 wt%. Thermodynamic non-equilibrium (Scheil) simulations, X-Ray Diffraction (XRD) analyses and Scanning Electron Microscopy/Electron Dispersive Spectroscopy (SEM/EDS) determined that all three alloys contain α-Mg solid solution phase, Al8Mn5 intermetallics and, depending on the Ca/Al ratio, combinations of C36-(Mg,Al)2Ca (hP24 a = 0.577–0.586 nm, c = 1.819–1.835 nm), binary C14-Mg2Ca (hP12, a = 0.620 nm c = 1.023 nm), ternary C14-Mg2Ca (hP12, a = 0.561–0.599 nm, c = 1.025–1.051 nm), and/or C15-Al2Ca (cF24, a = 0.793 nm) Laves phases. It is observed that Ca/Al ratio shows a direct relationship with the total amounts of Laves intermetallics and the amount of the C36 phase, and an indirect relationship with the amount of C14 phase. Microhardness measurements, room and elevated temperature (150 °C and 200 °C) tensile tests, as well as tensile creep tests (175 °C/50 MPa), were carried out to determine the mechanical properties of the alloys. Results show that the hardness and room temperature yield and ultimate tensile strengths (UTS) increase while the ductility at all temperatures decreases with increasing Ca/Al ratio. At elevated temperatures, in the range of Ca/Al ratios investigated, the UTS has a relationship with the dissolved amount of Ca and Mn in the α-Mg phase. Creep strain was found to decrease from 0.35% to 0.05% as Ca/Al increases from 0.6 to 0.9 and as the amount of the C36 phase which can strengthen grain boundaries increases. One order of magnitude improvement seen in creep resistance as the Ca/Al ratio increases from 0.6 to 0.8 is attributable to the presence of C36 and C14 phases rather than C36 and thermally unstable C15 phase in the alloys and to the increased amounts of dissolved Mn and Ca in the α-Mg matrix.

In this study, influence of different heat treatment conditions on microstructure, microhardness, yield strength, ultimate tensile strength, elongation and phase distribution of AZ63 magnes...

Hareketli protezler dis hekimligi protetik uygulama- larinda onemli bir yere sahiptir. Ancak tam protez- lerdeki ozellikle tutuculuk ve stabilite sorunu hastalarin en buyuk problemidir. Implant teknolojisinin gelismesi ve yayginlasmasiyla birlikte hareketli protezler de sabit protez sekline donusturulebilmistir. Hibrit protezler de- nilen bu implant destekli protezler sayesinde hastalarin daha rahat ve konforlu bir seklide kullanabilecegi pro- tezler yapilmaktadir. Bu derlemede hibrit protezlerin yapim kriterleri, avantaj ve dezavantajlari anlatil- maktadir. Anahtar Kelimeler: Implant, hibrit protez IMPLANT SUPPORTED HYBRID PROSTHESIS ABSTRACT The removable prosthesis have a significant role at prosthetic dentistry. However, especially retention and stability problems at complete prosthesis is the most significant problem of patients. With improving and widespread at implant technology, removable prosthesis can be transformed to fixed prosthesis. This is the hybrid prosthesis that it is supported implants, and prosthesis are made that patient can use more comfortable and easily. In this review, the treatment criteria, advantages and disadvantages of hybrid prosthesis are described. Key Words: Implant, hybrid prosthesis