Advanced Materials Research Vol. 1128

Abstract: The objective of this research paper is to examine the effects of adding an oxy-sulphide inoculant enhancer alloy [OS-IE = S,O,Al,Mg-CaSi alloy] to a conventional CaBa-FeSi alloy and to examine the graphite phase characteristics in these irons, as affected by different in the mould inoculants, for resin sand mould castings. The surface layer of all the Mg,RE-FeSi treated compacted / vermicular graphite cast iron samples with 0.018 – 0.023% Mg_res is influenced by S diffusion from Furan Resin–P-Toluol Sulphonic Acid (PTSA). The graphite phase is strongly influenced in this surface layer. Inoculation has a visible, beneficial effect in both the surface layer and the body of casting. Even with the highest solidification rate, at the surface layer of the 25mm round bar samples, the structure has the lowest graphite nodularity (15-20%), due to the sulphur content in the mould binder, in contrast with 40-50% nodularity in the casting body. Adding two inoculant type alloys Ca,Ba-FeSi + [OS-IE], led to the highest compacted / vermicular graphite formation. Inoculation with [OS-IE] only appears to encourage the formation of a high number of small graphite nodules that also display higher nodularity. This is represented by the second highest levels for circularity and sphericity shape factors at a much smaller inoculant addition, compared with a conventional Ca,Ba-FeSi inoculant addition. Inoculation with oxide-forming elements or pairing oxy-sulphide inoculant enhancer with commercial inoculants appears to be an economical alternative to rare earth (RE) based inoculants in compacted / vermicular graphite iron casting production.

Abstract: The paper presents experimental results regarding the evolution of hardness and impact energy of some sintered steels alloyed with 1.5% respective 3% (weight) copper powders. For the experimental research were used 3 mixtures: Fe+0.2C as reference, Fe+0.2C+1.5Cu, Fe+0.2C+3Cu. All the samples were die pressed at three pressures 400, 500 and 600 MPa and were subjected at three types of treatments as following: SINT, SINTCARB and CARBSINT. For the sintering treatments was used argon atmosphere and for carburizing process was used methane. After each treatment the hardness and impact energy for all the samples were measured and were made correlations between these properties and the type of treatment and copper content.

Abstract: As it is known the improving of the casting alloys properties supposes both finishing and modifying their structure. Dates from castings production specify that for structure improvement the metallurgical methods are more preferred than physical ones. The study analyzes the structural changes caused by melt vibration during crystallization of hypoeutectic and eutectic silumins and of the aluminum-copper alloy. The analysis of solidification conditions was achieved by recording cooling curves, and by the qualitative and quantitative examination of the obtained structures. The monitoring of the cooling intensity with or without mechanical vibrations was performed by calculate the global thermal transfer coefficient. It was followed in the same time the influence of mechanical vibrations on the casting alloys compactity. Global thermal transfer coefficient value increased 3.5 times.

Abstract: Inoculation is a treatment applied to the liquid base iron, to supply one or more elements, such as Al, Ba, Ca, Zr, Sr, Ce, La etc. with active roles in developing graphite nucleation sites. The efficiency of inoculants is directly dependent on the sulphur level: lower sulphur, lower inoculating power or unpredictable results. The objective of this paper is to examine the effects of a S and O containing inoculant enhancer [S,O,Al,Ca-FeSi alloy] to conventional Ca,Ba-FeSi alloy, in the mold treatment of electrically melted grey iron at 0.035%S, 0.002%Al, 0.0005%Zr, (%Mn) x (%S) < 0.02. The wedge test samples [W3 – ASTM A367] were used to evaluate the influence of the cooling rate and inoculation on the carbides formation. It was re-confirmed that for above mentioned critical chemistry conditions, this iron is sensitive to chill formation, despite the carbon equivalent level at 3.8%. Inoculation enhancement increased the effectiveness of the Ca,Ba-FeSi standard inoculant.

Abstract: Metallic biomaterials are used in various applications of the most important medical fields (orthopedic, dental and cardiovascular). The main metallic biomaterials are stainless steels, Co-based alloys and Ti-based alloys. Recently, titanium alloys are getting much attention for biomaterials because these types of materials have very good mechanical properties, good corrosion resistance and an excellent biocompatibility. The paper contains important information about titanium alloys used for biomedical applications, which are considered the most widely. It is very important to understand the microstructural evolution and property-microstructure relationship in implant alloys. In the present paper, authors present a short literature review on general aspects of promising biocompatible binary Ti-Mo alloys compared with CoCr and stainless steel alloys, as an alternative of the known metallic biomaterials. This alloys show superior mechanical compatibility and very good biocompatibility. The aim of this review is to highlight the mechanical properties for several types of biomaterials, their application in medical field, especially the Ti-Mo group.

Abstract: The Instrumented Indentation Technique (IIT) is used to measure the local mechanical properties of different materials. The mechanical parameters (indentation hardness and modulus) of multi-walled carbon nanotubes filled polypropylene (PP/MWCNTs) nanocomposites derived from the load-displacement indentation curve are investigated by sharp indentation. The effect of the visco-elastic-plastic deformations on the mechanical properties is studied considering a 5-step indentation test. The mechanical properties calculated based on the traditional Oliver and Pharr method are compared with those extracted from the new indentation methodology. During the 5-step indentation test, the viscoelastic deformations during the reloading-holding phases are reduced due to the decrease in the indentation displacement with the increase in the concentration.

Abstract: Increasing density is the best way to increase the performance of powder metallurgy materials. Conventional powder metallurgy processing can produce copper green compacts with density less than 8.3g/cm³ (a relative density of 93%). Warm compaction, which is a simple and economical forming process to prepare high density powder metallurgy parts or materials. CuSn matrix composites with %2 weight fractions of reinforcement particles were prepared using warm compaction and sintering. Micro-structural aspects were observed by optical microscope. Density, hardness and wear tests were also performed. Abrasion resistance measurements were used to study the abrasive behaviors of CuSn matrix and its composites. The effects of reinforcement and preparation methods on the microstructure and mechanical properties of composites have been investigated.

Abstract: Using new high entropy alloy with chemical formula AlCrNiCuMn produced by high technology (induction melt method), in manufacture of new composite materials will enable the creation of new structures resistant to stress used dynamic collective protection. Specify that High Entropy Alloys are characterized as alloys consisting of approximate equal concentrations of at least five metallic elements and are claimed to favor close-packed, disordered structures due to high configurational entropy. In this study, we investigate the microstructure and corrosion properties of AlCrNiCuMn high-entropy alloys. The type of high entropy alloys manufactured was a five-component alloy of AlCrNiCuMn. The microstructure and corrosion resistance property of high-entropy alloys AlCrNiCuMn were determined by scanning electron microscopy and electrochemical workstation. Microstructural characterization was performed by electron microscopy on LMHII VegaTescan equipment using a secondary electron detector (SE) at a voltage of 30 kV electron gun.

Abstract: In recent year's aluminium and aluminium alloys are widely used in automotive industries. These are light (density of about 2.7 g/cm³), having good malleability and formability, high corrosion resistance and high electrical and thermal conductivity. Metal matrix composites (MMCs) are being employed in industrial applications since they have high specific strength, stiffness, and good wear properties. Due to their favourable properties, composite materials with reinforcements are used in many industries. With the aim to additionally improve some of their properties, especially their tribological properties, several solid lubricants are used in the process of composite production. This paper gives an overview of investigations and possibilities of solid lubricant particles (such as graphite) applying as complementary material, mainly for aluminium base composites that are nowadays common in use in automotive and aeronautics industry.

Abstract: In this study we investigated the possibility to use in implantology of a new composite made from antibiotic imbedded in polymer matrix with goal to merge the mechanical advantages of the metallic substrate with the excellent corrosion protection of the polymer and antimicrobial effect of the antibiotics. Furthermore the addition of small quantity of bioactive glass allows the antibiotic release and hastens the osteointegration. The biological properties of the coatings were tested including the microbial viability using Gram - and Gram + bacterial strains with known antibiotic susceptibility behavior. The proposed system could be used for development of new antimicrobial materials or strategies for fighting medical biofilm pathogens often implicated in the occurrence of chronic infections.