Advanced Materials Research Vol. 1114

Abstract: The influence of rare-earth metals adsorbed in the surface of the metallic material subject to thermochemical processing as well as of those pre-added in the material matrix on the kinetics of layers growth is presented in the technical literature. It is generally concluded that the presence of rare earths is accelerating the kinetics of layer growth.

Abstract: 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 investigated using X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).

Abstract: Reinforcing bar corrosion is a major cause of the degradation of reinforced concrete structures, because the high quantities of chloride de-icing salts used. In addition the increase in construction near coastal marine environments may increase the potential for corrosion deterioration in these areas. As a result, some structures of ordinary Portland cement concrete with carbon steel reinforcement are requiring repair and remediation long before their current specified service lives (typically 40-50 years) are reached [1]. Therefore, easier, faster and more reliable condition analysis techniques are required than those currently available to allow corrosion detection at an earlier stage and, thus, permit remedial action to be take before major repairs are required.

Abstract: Conformal metasurfaces are even more diffused in different fields from optics to electromagnetics. Advanced applications, as making object invisible to incident fields also known as cloaking, require high precision realizations, since the resonant answer of the system is very sensitive to geometry details. Practical realizations are provocative, since material characteristics and mechanical restrictions should also be considered. Multi- and inter-disciplinary interactions are mandatory to overcome such technological challenges. Due to its excellent esthetic characteristics, good physical and mechanical properties, Aluminium is widely used for deposition on different substrates: physical and chemical vapor depositions are very suitable for micro-metallization process and for the realization of multilayered structures. This paper presents some results about the behavior of a cylindrical-shape system realized by Al films deposition on flexible, polymeric organosilicon substrate.

Abstract: The main objective of this work is the development of new Ru-based Bond Coats (BC) as part of Thermal Barrier Coating Systems (TBC).So far, Ru-based systems have not been investigated in detail. We investigate the possibility of replacing the traditional materials used as BC, with Ru-based alloys. They are important candidats because RuAl has the same structure as NiAl, has properties superior to those of NiAl at high temperatures and last but not least, Ru is much cheaper than Pt.We have prepared a RuAl 50/50 at% alloy in an induction furnace which was subsequently subjected to oxidation in an electric furnace, in air, at 1100°C, for 10h.The alloy was analysed before and after oxidation using advanced microscopy techniques (SEM, TEM).The challenge of this research is to obtain an adherent and uniform layer of alumina after oxidation. The results so far suggest encouraging results.

Abstract: A few numbers of countries in the world are involved in geothermal exploration and geothermal development projects. In order to provide a stable power supply without increasing carbon dioxide on global environment problem, a basic condition need to be fulfilled. This condition is high reliability and high maintainability for the geothermal energetic pumps and turbines. Effective efficiency improvement and geothermal turbines system upgrading are very important and also fundamental economical factor. This means that CO₂ emissions into the atmosphere are minimal and a higher reliance on geothermal power generation would work on preventing global warming.The solution to climate changes threat is based now, mainly, on renewable and ecological sources of energy. Geothermal energy has the potential to play a significant role in moving the Europe and other regions of the world toward a cleaner and more sustainable energy system. In order to increase the reliability of geothermal steam turbines, assessing the materials life under geothermal environment condition will be an important step. The corrosion process in the geothermal turbine and pumps depends on temperature, pressure, chemistry, mechanical and vaporous carryover of impurities and water treatment (distribution between the vapors, the surface film and rotor blades material, heat transfer properties etc).The aim of this paper is to present a new coating method for geothermal turbines and pumps components using multi composite technology in order to obtain a protective layer to reduce corrosion damages. The results were very promising and the technique used, plasma jet spraying is a very good method to be used on the geothermal turbines and pumps components.

Abstract: For ensuring fuel consumption and pollution reduction, the researches made in the past decades considerable efforts to replacing steel with aluminum alloys in manufacturing auto bodies, or in naval transportation, because the promising weight saving. The researches consisted in general corrosion (the gravimetric index and the corrosion rate, Vcorr) and tensile tests (Rm, Rp_0.2 and A5) in correlation with microstructure analysis of heat treated Al-Mg-(Si) system samples alloy, in order to obtain the best corrosion resistance and high mechanical characteristics. The Al alloys in extrusion state were solution treated at 510 – 545oC for 10-60 minutes, quenched in water 30-50o C and artificial aging at 150, 180 and 210°C at different time of aging (1, respectively 3, 7 and 11 hours). After heat treatment the obtained alloys were corroded in solution of 53g NaCl + 1000 ml distilled water and boiled in these solutions for 8, 16 respectively 24 hours. The gravimetric index was determinate by mass loss measurements for all types of heat treatment conditions. After corrosion test, samples were prepared for optical microstructural analyzing and mechanical tested. We have compared the obtained results on Al-Mg and Al-Mg-Si alloys. Were established (i) the optimum heat conditions parameters for obtaining of highest values of mechanical characteristics and corrosion resistance and also (ii) was explained the structural evolution during age (precipitation) hardening for both systems.

Abstract: Hip resurfacing arthroplasty is an very interesting and controversial orthopedic concept in the last years [1]. In order to avoid the previous problems associated with the classical hip prosthesis type metal-polyethylene [2], different manufacturer propose the metal-metal prosthesis based on the reproducible quality of manufacturing of metallic components using Co-Cr alloys and better component fixation. Problems that have been encountered to be the reason for failing of the prosthesis can be different (dislocation, femoral neck fractures, vascular damage, avascular necrosis, raised metal ion levels), and could be related to three main aspects: factors related to the patients, surgical intervention and prosthesis [3, 4]. But a very important aspect is the biomaterials used, that will be discussed in the present paper in correlation with biomechanics and clinical aspects. Our study maked on a lot of retrieved BHR prosthesis used in one Romanian orthopaedic clinic present a higher rate of failure than the other similar studies made by other authors [5]. Starting from this point, we analyze carefully many components of the failed BHR prosthesis using stereomicroscopy, scanning electron microscopy (SEM) and EDS. Based on our experimental results especially at the interfaces metal-cement-bone, we identify different potential causes of failure but the main conclusion was that the cementation technique and poor quality of the patient bone are the reasons for most of hip resurfacing prosthesis failure. As future recommendations for the orthopaedic surgeons we could mention the carefully analysis of bone quality for each candidate using advanced techniques like DEXA and a correlation between the bone cement used for prosthesis fixation and the cementation technique.

Abstract: Evolution of hernia surgery has led to polymeric biomaterials for replacement or reinforcement of the abdominal wall. Their selection, according to the structure and porosity of the material, is directly dependent on the surgical procedure used and interaction between material and abdominal viscera. The objective of the paper is to establish a protocol for the selection of hernia mesh fixation materials based on polymer structure related to the surgical procedure used. The biomaterials that promote infection should be avoided and those that do not provide a long-term mesh placement should be used in combination with other devices to compensate for this fault. In conclusion, is much better to adapt the fixation biomaterials used in clinical practice to the specific surgical procedure, given the physical and chemical characteristics of these polymers, in order to reduce the morbidity associated with this type of surgery.

Abstract: Typical applications of metallic dental materials include metal-ceramic restorations, dental implants or orthodontic systems. Due to their contact with human tissues, corrosion resistance is one of the main requirements for dental materials. In the present paper, the corrosion behaviour in Fusayama Meyer artificial saliva solution (pH=5.2) on a selection of four different metallic dental materials (316 L steel, Au based alloy, cp-Ti, Ti6Al4V alloy) currently used in dentistry were investigated. The metallic dental materials have been investigated in terms of electrochemical analysis, chemical composition, morphology before and after corrosion, wettability and roughness. The results showed a hydrophilic behaviour in the case of Au based alloy, cp-Ti and Ti6Al4V alloy, and hydrophobic for 316L stainless steel. Considering the main electrochemical parameters, the cp-Ti alloy exhibited better corrosion resistance in artificial saliva with pH=5.2, followed by Au based alloy, Ti6Al4V alloy and 316L stainless steel. The main objective of the present paper was to evaluate the corrosion behaviour, as in important factor in the selection of metallic materials used in dentistry.