Sorin Ciuca - Academia.edu (original) (raw)

Papers by Sorin Ciuca

Revista De Chimie, Dec 15, 2018

Increasing biocompatibility of implant materials is an important factor in developing better and ... more Increasing biocompatibility of implant materials is an important factor in developing better and long-lasting implants that function in a very close way to real tissue and bone. Various alloys have been chosen due to their biocompatibility, such as: stainless steels, titanium alloys and nickel or cobalt alloys. According to the alloying elements it is possible to change the material properties to fit into various application niches such as pacemaker devices, stents, biosensors, dental or bone implants and others. Some alloying elements confer higher biocompatibility than others and the commonly used alloys include elements that can be detrimental to human health such as Nickel, Vanadium and Cobalt. Choosing alloying elements such as Nb, Fe and Zr in order to replace the commonly used metals reduces the risks of accumulation of various substances that can damage the human tissues and lead to health complications. The proposed alloys are elaborated in a Five Celes melting furnace under argon atmosphere in order to create a more homogeneous material with lesser defects and inclusions. The cast alloys are then analyzed through modern methods such as SEM, XRD, EDS and their mechanical properties such as hardness and strength and these properties are compared to that of the bone in order to assess mechanical reliability.

Materials Science Forum, 1992

Surface & Coatings Technology, Sep 1, 2003

Using a relative simple experimental method, the sputtering rate has been measured under specific... more Using a relative simple experimental method, the sputtering rate has been measured under specific plasma nitriding conditions. The influence of gas composition and total pressure on the sputtering rate has been investigated. Depending on these factors, the sputtering rate varies in the range of 0.02–0.12 μm/h. The sputtered material has been analyzed as well. The results indicated that the phase constitution of this material is similar to that of the compound layer.

Materials and Corrosion-werkstoffe Und Korrosion, Mar 6, 2014

ABSTRACT The present paper is focused on three different aging treatment of a TiNi alloy in order... more ABSTRACT The present paper is focused on three different aging treatment of a TiNi alloy in order to enhance corrosion resistance in oral cavity environment. The best corrosion resistance in artificial saliva after aging treatment was found in the case of sample which was heat treated at 700 °C/20 min/water cooled, followed by aging at 400 °C/1.5 h/water cooled. Subsequent to such a heat treatment, the EDX surface analysis indicated an increase of Ti content of the matrix. This effect is in connection with stable and metastable precipitates which appear during the aging. Also, based on the greater affinity to oxygen of Ti compared to Ni, a uniform Ti based oxide layer is predominant explaining the better electrochemical stability. The obtained precipitates morphology is also an important factor in the corrosion behavior.

Journal of Applied Physics, May 1, 2005

The structural and optical properties of WO 3 nanorods prepared by oblique angle depositions were... more The structural and optical properties of WO 3 nanorods prepared by oblique angle depositions were studied and compared with WO 3 thin films. The x-ray diffraction analysis revealed that both the thin films and nanorods annealed at temperatures of 400 and 500°C had an orthorhombic structure, while only the thin films showed a monoclinic phase when annealed at 300°C. The band gap energies of the thin films and nanorods all decreased with increasing annealing temperature. The polarized optical absorbance spectra of the as-deposited nanorod samples initially showed anisotropy, but after annealing at temperatures above 400°C, they became isotropic. This is believed to result from the changes in morphology, crystal structure, and orientation of the nanorod arrays after annealing.

Annales De Chimie-science Des Materiaux, Dec 30, 2008

OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

HAL (Le Centre pour la Communication Scientifique Directe), 2008

ImportanĠa prezenĠei siliciului in mineralizarea osoasă a fost studiată in mai multe lucrări rece... more ImportanĠa prezenĠei siliciului in mineralizarea osoasă a fost studiată in mai multe lucrări recente. Hidroxiapatita fosfocalcică (HA: Ca 10 (PO 4) 6 (OH) 2) este principalul component mineral al osului. Această lucrare studiază obĠinerea apatitei dopate cu siliciu prin metoda "reacĠie solid-solid". Compusul stabil la temperatură înaltă pare a fi silicocarnotita. Totuúi, o apatită dopată cu siliciu a fost obĠinută prin incălzirea unui amestec de fosfat tricalcic, carbonat de calciu úi silice la 1200°C-1300°C. Materialul obĠinut poate fi folosit in medicină ca substitut osos sau ca strat subĠire depus pe suprafaĠa protezelor sau implanturilor osoase. Several studies have shown that silicon presence is beneficial in bone mineralization process. Phosphocalcium hydroxyapatite (HA: Ca 10 (PO 4) 6 (OH) 2) is the principal mineral component of bone. This work studies the synthesis of silicon containing apatite by a high temperature method. The stable compound at high temperature seems to be the silicocarnotite. Nevertheless, a silicon containing apatite has been obtained by heating a mixture of tri-calcium phosphate, calcium carbonate and silicon dioxide at 1200°C-1300°C. The synthesized materials can be used in medicine as bone substitution or as proĠsthesis and implant coating.

Advanced Materials Research, Jul 1, 2015

The paper presents results of researches carried out to establish the causes that led to the crac... more The paper presents results of researches carried out to establish the causes that led to the cracking of forgings made of manganese low alloy steel microalloyed with boron. The researches includes analysis of samples taken from the forgings in the cracked surface area and also analysis of a sample from forged material. The following methods and techniques were used for investigation:metallographic analysis by optical microscopy;visual macroscopic examination by scanning electron microscopy (SEM) at low magnification, using scanning electron microscope;examination by scanning electron microscopy on the material cracks area and its adjacent area;investigation of material by X-ray microanalysis in energy dispersive (EDAX) for its characterization, in terms of microcomposition;

Journal of Alloys and Compounds, 2012

ABSTRACT

Journal of Microbiological Methods, 2016

In this research work, the synthesis of Ag doped hydroxyapatite coatings for dental or orthopedic... more In this research work, the synthesis of Ag doped hydroxyapatite coatings for dental or orthopedic implants was performed. The main goal was to determine the influence of Ag content on the roughness and antimicrobial performance of the prepared thin films. The films were deposited on Ti6Al4V alloy by means of RF magnetron sputtering. Those coatings were characterized by X-ray diffraction (XRD) and 3D surface profilometry. The antifungal activity after 1 and 7 days of culture was evaluated in the presence of Candida albicans (ATCC-10231). The increase of Ag content increased roughness and reduced the antifungal activity. The results showed that the Ag doped hydroxyapatite coatings can be a potential solution for the improvement of the antifungal activities of Ti based alloy.

Journal of Materials Science: Materials in Medicine, Oct 4, 2007

Creatinine thin films were synthesised by matrix assisted pulsed laser deposition (PLD) technique... more Creatinine thin films were synthesised by matrix assisted pulsed laser deposition (PLD) techniques for enzyme-based biosensor applications. An UV KrF* (lambda=248 nm, tau approximately 10 ns) excimer laser source was used for the irradiation of the targets at incident fluence values in the 0.3-0.5 J/cm2 range. For the matrix assisted PLD the targets consisted on a frozen composite obtained by dissolving the biomaterials in distilled water. The surface morphology, chemical composition and structure of the obtained biomaterial thin films were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, and electron dispersive X-ray spectroscopy as a function of the target preparation procedure and incident laser fluence.

Applied Surface Science, 2005

Anatase phase titanium dioxide (TiO 2) thin films were grown by pulsed laser deposition on h0 0 1... more Anatase phase titanium dioxide (TiO 2) thin films were grown by pulsed laser deposition on h0 0 1i SiO 2 substrates. An UV KrF* (l = 248 nm, t FWHM ffi 20 ns, n = 2 Hz) excimer laser was used for the irradiation of the TiO 2 targets. The substrates were kept at room temperature or heated during the film deposition at values within the 100-500 8C range. The crystalline quality of the films and their chemical composition were investigated by X-ray diffractometry and energy dispersive X-ray spectroscopy. The optical properties were studied by a double beam spectrophotometer in the spectral range of 400-1200 nm. At substrate temperatures higher than 300 8C, the structure of the deposited thin films changes from poorly to well crystallised, corresponding to the tetragonal TiO 2 anatase phase. The average optical transmittance in the visible-infrared spectral range of the films is higher than 85% which makes them suitable for sensor applications.

IOP Conference Series: Materials Science and Engineering, 2020

4 TRIP steels were produced by use of an induction furnace with controlled atmosphere and vacuum,... more 4 TRIP steels were produced by use of an induction furnace with controlled atmosphere and vacuum, one of which having a completely new chemical composition with the purpose of obtaining an increased reaction during impact when compared to the other, already documented, steels. This study follows the heat treatment used in order to obtain the TRIP effect in the produced steels and the reaction that the steels exhibit when submitted to an impact test used to simulate a car crash at approximately 60 km/h. The preparation of the samples for both characterization and testing follow standard procedures in terms of analysis. The crash-like tests were performed by using an INSTRON 9340 Ceast which generated an impact energy of 18J. The comparison between the different types of TRIP steels helps to determine the best application of the purposed steel in the automotive industry.

As a 21st century trend, sustainability has encompassed the entire world economy, including indus... more As a 21st century trend, sustainability has encompassed the entire world economy, including industry. Today the concept of "Industry 4.0" is known, resulting from advances in ICT (information and communication technologies). In recent years, companies in the metal materials industry have also implemented strategies and technologies belonging to the Industry 4.0 concept. The main purpose of the manuscript is to identify the key issues in the evolution of the development of the metal materials industry. The transition to a higher level of its evolution is based on two vectors, namely: the ecological paradigm, as a vector of in-depth knowledge, and sustainable material, as a vector that ensures sustainability in the areas of convergence of systems in the spheres of life and social consciousness. The systems that have an impact on the sustainable development of the metallic materials industry, through the interactions between them, are: the technological system, the social sys...

Journal of Optoelectronics and Advanced Materials, 2007

Hydroxyapatite (HAP) thin films (0.2 μm, 0.3 μm and 1.2 μm thickness) were grown by RF magnetron ... more Hydroxyapatite (HAP) thin films (0.2 μm, 0.3 μm and 1.2 μm thickness) were grown by RF magnetron sputtering in argon atmosphere onto silicon substrates at high deposition rates (0.6 μm/h). Crystalline HAP films were obtained using a low temperature (100 °C) followed by post-deposition annealing at 300 °C, 450 °C, 500 °C and 550 °C in environmental air for 1 hour. An important influence of the films thickness upon the crystallization degree was noticed at intermediate annealing temperatures, as obtained from XRD measurements. For low and high temperatures similar values were obtained with a better crystallization degree for the thinner films. FTIR absorption led to the same conclusion considering the shape of stretching and bending PO 4 lines. This suggests that the crystallization process has a diffusion component besides usual thermal activation process.

Revista de Chimie, 2017

The alloy was chosen in order to obtain a shape memory alloy having a wider hysteresis than equia... more The alloy was chosen in order to obtain a shape memory alloy having a wider hysteresis than equiatomic NiTi, that involves a better thermo-mechanical stability. Two samples investigated by differential scanning calorimetry (DSC) were previously annealed at 800oC/12 h and, respectively, 900 �C/12 h followed by furnace cooling. These were afterwards submitted to thermal cycling. The thermal cycling of a Ni50Ti48Nb2 alloy sample previously annealed at 900 �C/12 h results in lower critical points and higher hysteresis values as compared to those of the sample annealed at 800�C/12h, also submitted to thermal cycling. Thus, annealing a metallic part made of such an alloy at 900� C/12 h followed by thermal cycling prior to putting it into service enhances its reliability.

Advanced Materials Research, 2015

The present paper shows the experimental results obtained on two complex alloys Co-Cr-W-C-Fe-Ni-S... more The present paper shows the experimental results obtained on two complex alloys Co-Cr-W-C-Fe-Ni-Si-Mn-Mo and Ni-Cr-Fe-B-Si-C-Co alloys deposited on copper support by welding (TIG). Well - known for their excellent abrasive wear, corrosion and high temperature erosion resistance, these materials were chosen as protective solutions for some highly mechanically and thermally stressed devices, namely the blast tuyeres of blast furnaces. A testing method which simulates as near as possible the real working conditions is the quick thermal shock, consisting in heating at the chosen testing temperature followed by cooling in cool air spray, for 25 cycles. Testing parameters were set according to the blast tuyere device working conditions. In this paper, the coatings microstructure’s comparative changes consequently to quick thermal shock were monitoring, because this affect the device lifetime and mechanical characteristics. The untested samples as well as on quick thermal shocked ones was ...

Key Engineering Materials, 2013

This paper aims to characterize two dental bridges made from Co-Cr alloy, the first one obtained ... more This paper aims to characterize two dental bridges made from Co-Cr alloy, the first one obtained by the conventional method (casting) and the second one by Selective Laser Sintering technique (SLS). The elemental composition, microstructure, hardness and corrosion behavior in artificial saliva were investigated, allowing a parallel analysis of this two samples obtained with the two methods mentioned above.

Surface and Coatings Technology, 2003

Materials and Corrosion, 2014