Advanced Materials Research Vol. 1128

Abstract: This paper presents the results of experimental research on thermal treatment of alloyed sintered steels and much the development of Fe‒3Mn‒1Mo‒1.5Cr‒0.5B‒0.45Graphite powder using mechanical alloying (MA). It was analyzed the influence of MA time on the morphology of the compound by electron microscopy SEM. The research has followed the study of the particle size powder mixtures influence obtained by mechanical alloying, compaction parameters and sintering process on the chemical and structural characteristics of the alloyed sintered steels. Thus there were compacted samples at 600, 700 and 800 MPa. The samples were heated using argon at a temperature of 1150°C using 60 minutes as a maintaining time. Cooling to the room temperature was achieved using a speed of about 30°C/ minutes. With the resulting steels, we have made metallographic determinations using optic microscopy and determinations of the main mechanical properties. Heat treatment took place (heating at 960°C and cooling in the H₂O solution and 10% NaCl) in order to improve the properties of alloyed sintered steel hardness and strength. Specimens quenched and tempered have high wear coefficient compared with specimens as-sintered.

Abstract: The central idea of the present research aims at achieving textile substrates through an efficient inclusion of a wild black cherry extract into the grafting agent-monochlorotriazinyl-β-cyclodextrin (MCT-β-CD). The methodology consists in a permanent/irreversible entrapment onto the fibres surface of the natural extract through inclusion mechanism. Exhaustion and sonication dyeing procedures were used alternatively. The obtained materials were characterized, by FT-IR and BET analysis. The experimental results reveal good adsorptive feature of the samples, due to a higher specific surface created by the inclusion complex (MCT-β-CD-dye pigment). An efficient blocking of the natural dye pigment molecules into the grafting agent’s cavity (MCT-β-CD), assumed both a stable dyeing and antimicrobial potential. The results obtained by this ecologic surface grafting method will contribute to novel key points in producing healthy natural textiles, as alternatives for single use textiles. The results provided by this research will be used as starting point for a future study targeting the obtaining of textile supports with antimicrobial performance. Other investigations like washing, rubbing and colour fastness, highlighted that dyeing treatment by sonication is extremely efficient and could be successfully applied to such items, in boosting developments.

Abstract: TThe present study is an attempt to observe and evaluate the dry rolling wear behavior [1] of three types of Ni-base coatings on an Amsler type wear machine, against low-alloyed steel discs. The tested coatings were obtained by flame spraying (on the same low-alloyed steel substrate as the discs) using commercial Ni-base self-fluxing powders: 1060-00 and 1355-20 type (manufactured by Hoganas) and JK 586 type (manufactured by Deloro Stelite Co). In order to increase the strength of the layers, the deposition was followed by fusing [2]. The tests were conducted on pairs of coated – uncoated discs at the same load and the same speed in all three cases. In order to evaluate the wear behavior, there were observed and measured the surface roughness and the rolling path profiles. A severe wear regime with adhesion as the main phenomenon was observed in case of the low-alloyed steel discs.

Abstract: The paper presents an example of calculation for the one-way repeated measures applied for the results of an austempered ductile iron. This research has a number of objectives which can be started as follows: 1. to determine of the volume fraction of retained austenite (Vγr); 2. the calculation for the one-way repeated measures applied for the results of the volume fraction of retained austenite (Vγr).

Abstract: The paper presents a comparison between Coordinate Measuring Machine and 3D white light scanning technologies as applied to the dimensional inspection of turbo-machinery parts such as turbine blade. The results were compared with the CAD model and each other. The results indicate that, even both methods are enough accurate with a slightly better accuracy for CMM, the operational speed and the variety of scanable surfaces give significant advantages to the 3D scanning method when prototypes require dimensional inspection by an alternative rapid route especially when dealing with objects with thin walls or sharp edges.

Abstract: This paper studied functional parameters: the angle of the shaft section (feed flow rotor) and rotor speed which directly influences the yield of screening with three types of sand (NR1, NC2 and NT3). Experiments was determined following an increase of the values of the shaft angle makes sifting efficiency decrease; the greater the passage section of the material, so the feed rate of the rotor, the efficiency decreases; and a higher rotor speed makes sifting flow to increase with increasing speed. Based on experimental data it was obtained a program that is subject to problem solving regression analysis in which the efficiency is represented as a function of two dependent random variables (speed and angle tilt rotor shaft/rotor speed and power flow rotor/angle tilting spindle and feed rate). The test is a prediction of the values output in certain circumstances depending the two variables. With these predictions decisions can be made for the construction/purchase or for screening.

Abstract: Despite the numerous theoretical and experimental studies carried out throughout the years, the use of the Coanda effect in the propulsion-related field definitely remains one of the most current discussion topics since no definite conclusion has been drawn yet regarding the capabilities, applications and performances of the devices based on the Coanda effect. The present paper sets out to present the theoretical quantitative and qualitative aspects of the most important uses of the Coanda phenomenon, including the author’s own interpretations and ideas.

Abstract: For the mathematical modeling of the bending behavior on a microgripper compliant arm it is necessary to estimate the compliance impact on the system. In case of low bending force values, the linear dependence between force and elastic deformation is presumed. After performing bending experiments on full section and, respectively, compliant arms, there was determined an elastic coefficient allowing the mathematical modeling of the compliant beam as a full section beam and a moment of inertia reduced proportionally to the calculated elastic coefficient. The modeling results are consistent with the results of the experiments performed on the prototype.

Abstract: Most metallic constructions and equipment which come in contact with petroleum products are made of steel and are exploited at ambient temperature which can range between −50°C and +50°C in different regions of our planet. When metals and alloys are in contact with pure hydrocarbons (C_nH_m), they do not react with them. However, rust or different types of depositions can be observed in tanks and pipelines containing gasoline, naphtha, and gas oil. The complex phenomenon of contamination is described in this paper in order to demonstrate its importance, as the number of failures of steel components is growing every year. It is important to understand that the corrosion process proceeds at the interface of different phases. Water, H₂S, corrosion products, ions, phenols, organic acids, and other organic sulphur-, oxygen- and nitrogen-containing compounds dissolved in petroleum products are the contaminants that are responsible for the further destruction of the steel components.

Abstract: Application of nanoparticles provides an effective way of improving heat transfer characteristics of fluids. Particles less than 100 nm in diameter exhibit different properties from those of conventional solids. Compared with micron-sized particles, nanophase powders have much larger relative surface areas and a great potential for heat transfer enhancement. Some researchers tried to suspend nanoparticles into fluids to form high effective heat transfer fluids. Some preliminary experimental results showed that increase in thermal conductivity of approximately 60% can be obtained for some nanofluids consisting of water and 5 vol% CuO nanoparticles. So, the thermal conductivity of nanofluid was found to be strongly dependent on the nanoparticle volume fraction. So far it has been an unsolved problem to develop a sophisticated theory to predict thermal conductivity of nanofluids, although there are some semi empirical correlations to calculate the apparent conductivity of two-phase mixture. In this article, several correlations for predicting the nanofluid thermal conductivity will be compared and results will be discussed for three water based nanofluids.