nicanor cimpoesu - Academia.edu (original) (raw)

Papers by nicanor cimpoesu

Archives of Metallurgy and Materials, Jul 26, 2023

Obtaining and analysis Of a new aluminium brOnze material using inductiOn furnace Copper-based al... more Obtaining and analysis Of a new aluminium brOnze material using inductiOn furnace Copper-based alloys with the addition of al present excellent properties and can be considered a proper choice for applications as contact materials based on their good strength and fret resistance. Cu-al alloys are used in different systems parts as bearings, gears and worm gears. The intention is to replace steel materials with new copper-based materials for parts that work in a possible explosive environment to reduce the possibility of spark appearance. Copper-berilyum alloys are known as non-sparking alloys and are used in different tools obtaining for environments with possible explosive gaseous. Results from the obtaining and analysis of a new alloy based on CualBe are given. The material was melted in a vacuum induction furnace from CuBe master alloy and high purity aluminium and cast into a metallic die. The alloys obtained were analyzed using eDs-energy dispersive spectroscopy for chemical composition, oM-optical and seM-electronic microscopy for the microstructure, and the electro-corrosion resistance was tested using linear Tafel diagram and cyclic potentiometry.

Environmental Engineering and Management Journal, 2011

The corrosion products of high strength low-alloyed steel and of cast iron, maintained a prolonge... more The corrosion products of high strength low-alloyed steel and of cast iron, maintained a prolonged period in natural seawater, were analyzed. A part of the corrosion products are soluble compounds of divalent and trivalent iron, the iron dissolution being accelerated when divalent ions are formed and in the case of the aerated seawater. The solid corrosion product formed during corrosion in seawater is principally oxy-hydroxide (FeOOH), but were identified small quantities of Fe 2 O 3 , Fe 3 O 4 and some crystals of sodium chloride polluted with calcium and magnesium. The FT-IR measurements have pointed out that the FeOOH have a poly-molecular structure. In dynamic heating conditions the decomposition of solid rust take place by three distinct processes: adsorbed water elimination, dehydroxylation of the FeOOH to amorphous Fe 2 O 3 and crystallization of Fe 2 O 3 .

Materials research foundations, Jul 5, 2021

The book reviews the current status of vehicle brake disc materials and technology. Topics covere... more The book reviews the current status of vehicle brake disc materials and technology. Topics covered include friction materials for braking systems, material characterization, mechanical properties, corrosion processes and methods for disc break investigations. The book references 158 original resources with their direct web links for in-depth reading.

IOP conference series, Jun 1, 2017

Nucleation and Atmospheric Aerosols, 2017

In this article we obtain thin layers from complex ceramic powders using industrial equipment bas... more In this article we obtain thin layers from complex ceramic powders using industrial equipment based on atmospheric plasma spraying. We analyze the influence of the substrate material roughness on the quality of the thin layers using scanning electron microscopy (SEM) and X-ray dispersive energy analyze (EDAX). Preliminary results present an important dependence between the surface state and the structural and chemical homogeneity.

Industrial Crops and Products, Dec 1, 2016

In this study was reported a novel application of using vegetable waste such as fall quince leave... more In this study was reported a novel application of using vegetable waste such as fall quince leaves for wool fibers dyeing. Natural dye obtained by aqueous extraction of quince leaves (Cydonia oblonga) was applied to a wool fibers by an exhaustion dyeing process. Effect of extraction temperature on UV-vis absorbance of the extracted liquor was studied. Zinc chloride and silver nitrate were used as mordants. The dyeing process was conducted with and without metallic salts, using post-mordanting method. The fastness properties and color parameters of the dyed wool samples were determined. The antimicrobial activity of dyed and post-mordanting wool fibers was also evaluated. Dyeings with aqueous extracts of fall quince leaves have moderate to very good fastness properties. Mordanting with silver nitrate result in significant improvement in light fastness. The best results were achieved when dyeing was conducted with quince leave extracted at 100 • C. Wool fibers dyed with mordant had a darker reddish-brown shades than those dyed without mordant. However, darker shade was obtained with silver nitrate mordant. Dyed and postmordanting samples with silver nitrate have a good antibacterial activity against Gram-negative and Gram-positive bacteria. It was found from the study that the dye extracts from fall quince leaves can be successfully used for dyeing of wool materials to obtain a wide range of shades from light beige to reddishbrown. "Green waste" obtained from forest and garden residues could be used as valuable resource of natural dyes and bioactive compounds.

IOP conference series, Aug 2, 2019

Numerical analyse present a proper solution in order to investigate and quantify what is difficul... more Numerical analyse present a proper solution in order to investigate and quantify what is difficult to appreciate during technical processes. The simulated results are very close to those obtained experimentally fact that creates a big advantage in simulation process usage. Parameters like filling time and filling sequence, solidification time and cooling rate were evaluated for two metallic materials. Different dimensions and geometries of applicative elements influence considerably the casting behavior of a material even if the process is realized in the same conditions.

Conference proceedings of the Society for Experimental Mechanics, Sep 20, 2016

The reversibility of the phase transformation in shape-memory alloys (SMAs) directly governs the ... more The reversibility of the phase transformation in shape-memory alloys (SMAs) directly governs the mechanical response of these materials. Infrared thermography is used in this study to measure the mechanical dissipation produced by copper-based SMAs under cyclic loading at ambient temperature. Several specimens with different chemical compositions are tested. Mechanical dissipation which is produced by the material is deduced from the temperature change using a 0D version of the heat equation. Results obtained show that the chemical composition as well as the nature of the phase involved (martensite or austenite) influence the mechanical dissipation produced by the specimens during cyclic mechanical loading.

Revista De Chimie, Dec 15, 2017

Complex ceramic superficial ceramic layers (Al 2 O 3 , SiO 2 , YO, ZrO 2) were obtained by atmosp... more Complex ceramic superficial ceramic layers (Al 2 O 3 , SiO 2 , YO, ZrO 2) were obtained by atmospheric plasma deposition, industrial wide application method, on a metal support Fe-C (FC 250). The substrate was sandblasted mechanically prior to depositing 6 successive layers of ceramic material. The obtained layers were analyzed structurally (scanning electron microscopy, SEM), chemical (spectroscopy of X-ray, EDAX) and mechanically (scratch tests) to characterize the new compound material obtained (thin layer-substrate). It was observed from the experimental results that there was a relationship between the state of the surface of the substrate and the adhesion of the ceramic layers to the metal surface.

Metal Science and Heat Treatment, Mar 1, 2017

The effect of deformation on the damping capacity of a copper-base shape memory alloy produced by... more The effect of deformation on the damping capacity of a copper-base shape memory alloy produced by standard methods is studied. The metallographic analysis is performed with the help of scanning electron microscopy. The internal friction is measured at different temperatures. The damping capacity of the alloy is analyzed and its relation to the mechanical and physical properties is determined.

Ceramics International, Oct 1, 2019

Ceramics International, Jun 1, 2023

Materials and Corrosion-werkstoffe Und Korrosion, Feb 15, 2016

The electrochemical behavior of Zr5Ti, Zr25Ti, and Zr45Ti alloys with surface modification was mo... more The electrochemical behavior of Zr5Ti, Zr25Ti, and Zr45Ti alloys with surface modification was monitored in phosphate-buffered saline (PBS) solution, at the normal pH of the internal medium specific to healthy state (pH ¼ 7.3), and hydrogen peroxide added to PBS solution in order to simulate the inflammatory state, with a more acid medium (pH ¼ 4.9). A passive behavior for thermally oxidized ZrTi alloys was registered using linear potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Very low passive current densities were obtained from the anodic polarization curve, showing a passive behavior for all ZrTi alloys. The EIS data for all three alloy compositions were recorded for both pH solutions after 1 day, and 7 days immersion. From EIS data, an equivalent circuit (EC) for two time constants was modeled. The results showed that the Zr45Ti alloys with surface modification may be considered as potential candidates for biomedical applications based on their corrosion resistance in PBS solutions.

Journal of Essential Oil Research, May 7, 2014

This research aimed to produce personal care biomaterials with an antimicrobial and flavoring eff... more This research aimed to produce personal care biomaterials with an antimicrobial and flavoring effect that allowed the controlled release of biologically active constituents. We investigated the manufacturing conditions of oil-in-water-type chitosan emulsions encapsulating geranium essential oil and the influence on controlled release and antimicrobial effect of the biologically active compounds. The materials were obtained by applying the polymeric matrix/biologically active principal system on a 100% cotton textile substrate. Seven treatment variants that differ one from another by the concentrations of the two components of the system (the polymer and the biologically active compound) were used. The release profile of the biologically active principal from the treated textile substrate was analyzed according to the Peppas kinetic models. The results suggest that the forming of emulsions should be processed under the following conditions: a concentration of chitosan of 0.250% (w/v), geranium essential oil 0.450% (w/v), Tween 80 1% (w/v) and glycerine 2% (w/v), so that we could obtain biomaterials with the best controlled release of biologically active compounds.

Materials Today: Proceedings, 2023

Materiale Plastice, Sep 30, 2017

Key Engineering Materials, Aug 1, 2017

New requests from the automotive industry suppose to apply new materials with mechanical resistan... more New requests from the automotive industry suppose to apply new materials with mechanical resistance to heat and vibrations and also with low weight. In order to replace plastic materials with high damping capacity a viable solution can be the metallic materials with sufficient internal friction to transform the external mechanical energy in thermal energy without affecting the microstructure or the mechanical properties of the metallic materials. In automotive applications an important role, especially in low velocity impacts, are the bumper elements. In this article possibility of copper-based shape memory alloys to fulfill the damping necessity of metallic materials is analyzed. Dynamic - mechanical analyze of few copper based shape memory alloys is realized and the results compared to proposed a better solution of Cu-based shape memory alloy for damping materials applications. The damping capacity difference between martensite and austenite like phases is also analyzed.

Applied Physics A, Jul 16, 2020

In the herein paper, the possibility of obtaining spontaneous surface relief gratings (SSRGs) on ... more In the herein paper, the possibility of obtaining spontaneous surface relief gratings (SSRGs) on azo-polymeric film surfaces, using a single laser beam of 1.13 mJ energy in pulse mode, was investigated. Chain rigidity is essential to have SSRG of reasonable quality so three azo modified polymers, with different main-chain rigidity, were considered: poly(chloromethyl styrene) (PCMS), a linear polysiloxanes and a cyclic polysiloxane. The AFM studies on azo-polysiloxanes revealed unregulated networks with amplitudes of only 1 nm, while on PCMS orderly SSRGs were observed. These results showed that the more rigid azo-polymer, PCMS, had better capacity to generate SSRGs of high quality. The SSRG periodicity was correlated with the number of laser pulses, i.e. higher pulse number led to lower periodicity. The SSRGs formation was associated with polymeric chains self-organization favoured by photo-fluidisation.

Materiale Plastice, 2010

The internal friction phenomenon in metallic and polymeric shape memory materials is analyzed. Th... more The internal friction phenomenon in metallic and polymeric shape memory materials is analyzed. The experimental results permit validation of a theoretical model which describes qualitatively the temperature dependence of the internal friction for the investigated materials. Moreover, theoretical model accepts not only evaluations of different states of material (solid state structural transformations as martensite-austenite) but also materials very different as nature (metallic or plastic).

Materials Today: Proceedings, 2019

The fall arrest safety system accessories used to connect and reconnect quickly the components of... more The fall arrest safety system accessories used to connect and reconnect quickly the components of these systems are called carabiners. The main components of these metallic links are: the nose, the river pin, the frame and the spine of frame, the gate with or without the locking sleeve. The carabiners are used in multiple domains, such as arboriculture, navigation, caving, industry, etc. Because these shackles get into contact with various corrosive substances, as example salty water, the corrosion resistance of carabiners manufacturing material is a very important property, therefore its improvement can increase the carabiner durability and the user safety. To improve the impact resistance and corrosion properties of carbon steel carabiners (used in industry or rescue operations) a layer of insoluble phosphates and rubber paint was applied on the metal surface. The aim of this study is to analyze the tribological characteristics of the phosphate and rubber paint layers. Hardness and elasticity modulus were determined by microindentation and the scratch test was performed in order to evaluate the adhesion and friction coefficient. Both analyses were made with a mechanical and tribological equipment called UMTR 2M-CTR Micro-tribometer.