Key Engineering Materials Vol. 583

Abstract: The paper emphasizes the importance of use the nano-iron oxides as treatment materials for wastewaters decontamination, having in mind the size of these compounds and specific surface area suitable for retaining toxic metals such as chromium or cadmium presented as major pollutants for industrial wastewaters. Also, the magnetic properties of the nano-iron oxides offer the possibility of a fast removal of these from the system, after wastewaters treatment. The obtaining of some core-shell composites with nano-iron oxides as core represent an advantage because of the dissolving tendency of the nano-iron oxides under acidic conditions, the situation being common to the industrial wastewaters.

Abstract: Stainless steels, commercial as well as with special properties, are the principal metallic materials used for medical devices manufacturing. Stainless steels for medical devices should have superior mechanical properties, as: hardness, wear resistance, tensile strength, elongation, fracture toughness, creep resistance etc. This paper aims to present experimental researches regarding the obtaining in vacuum arc remelting device (VAR) of austenitic and martensitic stainless steels and their characterization from microstructure and microhardness point of view.

Abstract: Biocompatible metallic materials used for surgical implants in human body should have superior mechanical properties, as: microhardness, wear resistance, tensile strength, elongation, fracture toughness, creep resistance etc. These results can be also obtained by strict setting and controlling of chemical composition, by adding chemical elements that lead at the improvement of the mentioned properties. In this paper has been presented experimental researches regarding the obtaining process of some biocompatible Co-Cr cast alloys, having different chemical compositions, using the method of vacuum induction melting (VIM). After the obtainment process, samples were characterised from microstructure and microhardness point of view.

Abstract: This paper aims to present the mechanism of PECVD SiOx coating thin layer technology on biomaterials, such as Ti and its alloys, with reference to the available literature. The thin organosilan coating surface will be analyzed by SEM technique and the corrosion behavior by EIS technique. The study shows that plasma-assisted fabrication allows us to prepare dense, homogeneous and high adherent coatings and thereby, will improve the corrosion resistance.

Abstract: Cavitation is an important factor in many areas of science and engineering, including acoustics, chemistry and hydraulics. In this paper the authors analyze the structural analysis of cavitation damages in two steel. The cavitation erosion tests were carried out in a magnetostrictive facility, in Timisoara Hydraulic Machinery Laboratory, in according with ASTM G32-85, using as cavitant liquid drink water at 20 10C. After quantitative and qualitative investigations structural features were put in evidence on experimental steel

Abstract: Being the lightest structural element, magnesium and its alloys has attracted significant interes in the last years, but because of its hexagonal close packed structure, magnesium presents relatively low strength and ductility. One of the methods to improve the mechanical properties of the processed materials is through Severe Plastic Deformation (SPD). ZK60 magnesium alloy samples were subjected to 4 passes of equal-channel angular pressing (ECAP) at a processing temperature of 250°C, following route A. The microstructure was determined with an Olympus BX51 optical microscope. Differential Scanning Calorimetry (DSC) was used to estimate the stored energy and the recrystallization temperature after each ECAP pass.

Abstract: The removable partial dentures are made of alloys from CoCrMo system. This survey work paper considers various commercial CoCrMo alloys that were investigated in terms of surface behavior through different processing methods, respectively: sand blasting, grinding, milling, smoothing and polishing, procedures applied in accordance with the necessary standards for prostheses processing in dental labors, regarding their final trimming. Alloys behavior highlighting was performed by macrostructural investigations carried out at stereomicroscope. In the end an alloy hierarchy was achieved according to the method in which the main macrostructural aspects were highlighted.

Abstract: Metallic implants for ostheosynthesis are used for temporary replacement of the the original functions and to accelerate the bone consolidation after fracture. Stainless steel is frequently used for bone fracture fixation in spite of its sensitivity to corrosion in aggressive environments such as human body 1. This study is focused on the effect of associated use of various metallic implants for osteosynthesis and the occurrence of local adverse reactions as a tissue response. Once the degradation process occurs metal ions are released and are held responsible for these undesirable effects. This was the main motivation of starting a comprehensive study which involved the clinical data of patients who underwent such surgery, analysis of tissues around the implants and also investigation of metallic explants through microscopy techniques.

Abstract: A technique to control the crystallinity of hydroxyapatite (HA) was investigated for applications such as dentistry, regenerative medicine, cell culture scaffolding, and bio-sensors. An amorphous HA film was first produced by pulsed laser deposition. After deposition, it was separated from a substrate as a free-standing sheet. Annealing was then performed to control the crystallinity of the sheet. It was found that conventional annealing in an electric oven was not suitable for HA sheets, because it led to curling and cracking. Since such problems were assumed to be caused by thermal stress, annealing was next carried out with the HA sheet enclosed in HA powder in the center of a metal capsule. This method allowed annealing to be successfully carried out without causing any curling or cracking. Uniform pieces with dimensions of 10 mm × 10 mm cut from a large HA sheet were annealed at temperatures of 200 to 800 ^ºC and then examined using X-ray diffraction. It was found that the intensity of the diffraction peaks associated with crystalline HA changed with annealing temperature, and that the strongest peaks were observed for the sample annealed at 500 ^ºC. These results indicate that the crystallinity of the HA sheet can be controlled using the proposed method.