Advanced Materials Research Vols. 875-877

Abstract: Results from an experimental investigation for diesel soot oxidation strategy using high-frequency electromagnetic waves in producing metal sparks is provided in this paper. It is envisaged that the micro plasma develop by metal when subjected to high-frequency electromagnetic waves, produces heat that enables soot oxidation process. The work attempts to investigate the relationship between spark inception of metals and micro plasma temperatures at different microwaves intensity. Various metal specimens were exposed to high-frequency electromagnetic waves at different power levels at a specific duration of time. The sparks temperatures or micro plasmas produced by the metals were measured using a high-range infrared thermometer. It was found that aluminum and brass have high spark temperatures when compared to mild steel at lower microwaves power levels. However, both aluminum and brass have lower melting point temperatures than mild steel. This makes the material unsuitable for prolong exposure to high-frequency electromagnetic waves. Mild steel was found the suitable metal to be used as the spark inceptor in the soot oxidation reaction chamber.

Abstract: SbSe nanoisland films have been grown via incongruent evaporation of Sb_1xSe_x films, and their surface morphology has been studied by atomic force microscopy. The surface density and characteristic dimensions of the islands have been shown to depend on evaporation time and temperature which correspond to range of quantum size spectrum of electron states and indicates the possibility of controlling growth-oriented quantum-well structures with desired properties based on Sb₂Se₃.

Abstract: Removed at authors request

Abstract: Cast aluminum alloy 354 is used extensively for production of critical automobile components, owing to its excellent castability and attractive combination of mechanical properties after heat-treatment. With the advent of higher performance engines, there has been a steady demand to further improve the mechanical behavior of the castings made of the alloy, among others, through improvements in processing. The present study explores the possibility of improving tensile properties of the alloy by adopting certain non-conventional aging treatments. The non-conventional treatments include aging cycles similar to T6I4 and T6I6 referred to in the published literature, artificial aging in two steps instead of in single step and artificial aging preceded by various natural aging times. The results show that none of these non-conventional treatments leads to improvement of all tensile properties compared to the standard T61 treatment. Significant hardening takes place in the alloy due to natural aging. Changing the time of natural aging preceding artificial aging was found to have little effect on tensile properties.

Abstract: This study presents the results of machining tests carried out determine the effect of cutting forces and surface roughness on machininig of 2080 Special K (1.2080 DINX210Cr12) cold work steel in terms of cutting speed, feed rate and depth of cut for milling process. A series of experiments have been performed on 2080 Special K steel material of cutting width 50 mm with round uncoated cemented carbide insert on 5,5 Kw engine power Jhonford VMC550 CNC vertical machining center without cutting fluid. Experiments were carried out by using four different cutting speeds (70,90,110,130 m/min) at constant depth of cut (1mm) and feed rate (0,3mm/rev.) and the effects of cutting speeds on primary cutting force and surface roughness were investigated. The study of the influence of workpiece material on milling process shows that hardening of material increased by machining up. Cutting force (Fc) and surface roughness decreases with improving workpiece material machinability. From the experiments, the lowest average primary cutting force was obtained as 604,03N at cutting speed of 90m/min. The lowest average surface roughness has been obtained as 0,19 um at cutting speed 110m/min. Obtained chip form is narrow and short step.

Abstract: This paper presents the detailed discussions on fabrication of Aluminium - silicon carbide (10% by weight of particles) and boron carbide (5% by weight of particles) Hybrid Metal Matrix Composites (Al/SiC/B₄C MMC) using stir casting method. SiC and a B₄C particle range from 30μm to 50 μm. The cylindrical rods of diameter 60 mm and length 250 mm are fabricated and subsequently machined using medium duty lathe of 2 kW spindle power to study the machinability issues of Hybrid MMC using Poly Crystalline Diamond (PCD) insert of 1600 grade. The optimum machining parameters have been identified by a composite desirability value obtained from desirability function analysis as the performance index, and significant contribution of parameters can then be determined by analysis of variance. Confirmation test is also conducted to validate the test result. Experimental results have shown that machining performance can be improved effectively through this approach. Results show at higher cutting speeds, good surface finish is obtained with faster tool wear. It is concluded that, tool wear and cutting force are directly proportional to the cutting speed, where as surface roughness is inversely proportional to the cutting speed. Percentage of error obtained between experimental value and predicted value is within the limit.

Abstract: In the development of modern welded structures with longer life-time and/or higher load-carrying ability, fatigue properties are becoming more and more important. A lot of researches have been done to investigate which factors can elongate the fatigue life of weldments. Cold lap defects, were found to be important initiation sites of the fatigue failure in 1990s. In the ISO standard, cold lap is referred to as a type of micro-lack of fusion. Previous study found that most of the cold laps in GMAW process are formed in spatters. In this paper the interface of spatter/base metal was cut, polished and investigated by conventional metallographic methods. The aim is to reveal the influence of temperature on cold lap formation. In the experiments, different pre-heating temperatures of the parent plate were used in tandem GMAW. Results showed linear empirical relationship between the temperature of the parent plate and the amount of lack of fusion in the spatter/base metal interface.

Abstract: Cast aluminum alloy 354 is used extensively for production of critical automobile component, owing to its excellent castability and attractive combination of mechanical properties. With the advent of higher performance engines, there has been a steady demand to further improve the mechanical behavior of the alloy, among others, through improvements in processing. The present study explores the possibility of improving mechanical behavior and quality levels of the alloy by adopting certain non-conventional aging treatments. Quality indices Q and Q_C have been used for quality rating. The non-conventional treatments include aging cycles similar to T6I4 and T6I6 referred to in the published literature, artificial aging in two steps instead of in single step and artificial aging preceded by various natural aging times. The results show that none of the non-conventional treatments leads to improvement of all tensile properties compared to the standard T61 treatment. However, some specific treatments could be identified which lead to a comparable combination of tensile properties and a shade higher quality level. Increasing the time of preceding natural aging does not help in improving the tensile properties after artificial aging.

Abstract: In the paper the actual state and prospects of applicability of a high power electron beam technology for manufacturing metallic as well as nonmetallic composite materials mostly for electric contacts and electrodes are presented and discussed

Abstract: Centralized manufacturing and distributed manufacturing are two fundamentally different methods for producing components. This work describes a centralized manufacturing scenario in which parts are produced via forging and finish machining at one central location and are then shipped to the end user. The distributed manufacturing model involves a scenario in which an additive manufacturing process (Electron Beam Melting) is used to produce parts to near net shape with minimal finish machining. Because the process doesn’t require molds or dies, production can take place in small production quantities “on demand” at job shops located close to the end user with little transportation. This is in stark contrast to the centralized model where large quantities of parts are produced and then distributed at a later date when needed from warehouses. The aim of this research is to compare the environmental impact of these two different production approaches under a variety of conditions. The SimaPro software has been used model both approaches with input from the user involving part size, amount of finish machining, transportation distances, mode of transportation, production quantities, etc.