Advanced Materials Research Vols. 1025-1026

Abstract: The aim of this research paper is to study the effect of particle size of recycled polymeric material to mechanical tensile properties. During grinding particles are formed which have a different size, shape and surface, from larger pieces to dust particles. During processing these particles melt at different rates depending on their size. For example they can cause material degradation or lack of melt homogeneity. Several recycled mixtures were prepared that had differed particle size after crushing. The recycled material is always the same as is the original material. The studied material was a Polycarbonate. Testing was performed using a tensile test. When comparing a virgin polycarbonate with recycled mixtures, the particle size of the recycled material affects some of the material parameters quite substantially, but it had no effect on some other properties.

Abstract: Delivery of polymer melts into the mold cavity is the most important stage of the injection molding process. This paper shows the influence of cavity surface roughness and technological parameters on the flow length of rubber into mold cavity. The fluidity of polymers is affected by many parameters (mold design, melt temperature, injection rate and pressures) and by the flow properties of polymers. Results of the experiments carried out with selected types of rubber compounds proved a minimal influence of surface roughness of the runners on the polymer melt flow. This considers excluding (if the conditions allow it) the very complex and expensive finishing operations from the technological process as the influence of the surface roughness on the flow characteristics does not seem to play as important role as was previously thought. Application of the measurement results may have significant influence on the production of shaping parts of the injection molds especially in changing the so far used processes and substituting them by less costly production processes which might increase the competitiveness of the tool producers and shorten the time between product plan and its implementation.

Abstract: The segment of wood preservation is responsible for considerable waste generation, typically consisting of products not approved by quality control or post-consumer. Another type of waste to be considered is tire rubber, which accumulate due to deficiencies in logistics and fiscalization. Although it has been classified as intractable, tire rubber enables to add properties in products that promote the use of materials in particulate form. This study aimed producing and characterization of particulate composites containing CCB-treated Pinus sp. with addition of tire rubber, and castor oil-based polyurethane resin. Properties of particleboards were obtained according to Brazilian Code NBR 14810:2006. The results were compared by statistical analysis. It was observed that addition of tire rubber waste resulted in higher densities, and rubber proportion of 50% showed greater internal bond. In some cases, strength in bending of panels was in accordance with standards requirements and commercial products destined for acoustic conditioning, enabling different applications.

Abstract: Pin-on-disk technique was used as a tool to study the tribological properties of contacting surfaces of alumina-titanium carbide composite material and diamond slicing blade. Conditions for testing are linear sliding speed between 0.2 and 0.4 m/s under applied load of 10 N and sliding distance up to 5000 m. The physical properties of both specimens which are mass loss, surface roughness and morphology of worn surface are investigated. The effect of linear sliding speed is analyzed in term of friction coefficient, surface roughness, and specific wear rate. It was found that, at initial state of wear, when sliding distant is less than 1000 m, the wear is severe, as seen by high values of specific wear rate and large fluctuation of friction coefficient. Worn surface of AlTiC is rougher than as-received condition. For a longer sliding distant, milder abrasion is found, as seen by the lower specific wear rate, and less fluctuation of friction coefficient, which produces worn AlTiC surface which is smoother than the as-received condition.

Abstract: In the present work, a technique and model for temperature prediction at the blow end are briefly discussed, along with their limitations and perspectives for application. As a result of this analysis, a mathematical model based in heat and mass balances has been developed with a view to evaluating the possibility of improving this prediction capability. The study here presented focuses the development of a semi-dynamic control model in the LD-KGC converter (Linz-Donawitz-Kawasaki Gas Control Converter). The control model enables one to predict the temperature of the blow end by solving both the energy and mass equations. The inputs to the control model are the load data of the LD-KGC converter at the blow beginning and the collected data by the lance to 89% of oxygen blow. The results obtained in the present work were compared to the data measured in steelmaking. The semi-dynamic control model results agree well with data for LD-KGC converters.

Abstract: The present studies investigate the wear response of composition-modulated multilayer Ni-W coatings as fabricated by electrodeposition. By regulating the pulse waveforms of the applied currents, the chemical composition, grain size, and the individual layer thickness of the electrodeposited Ni-W CMMC can be tailored. The ball-on-disc test and the subsequent microstructural analysis indicates that the wear resistance and friction coefficient of Ni-W CMMC are influenced by the composition and the thickness of the individual alternating layer. The decrement of interlayer’s size monotoically increase wear resistance and friction coefficient.

Abstract: Weld hardness has close relationship with creep strength and ductility of the welded structures. Hence it is important for any weld to achieve certain level of weld hardness. This study aims at identifying the parameters that affect the quality of weld in achieving the required weld quality in terms of hardness and to establish the relationship between different factors that affect the weld hardness. The focus is to study and explore the welding input parameters for the gas tungsten arc welding (GTAW) of elevated temperature piping used in power plants and to predict the weld hardness on construction sites. The Design of Experiment (DoE) is used in analyzing the related parameters. The data generated through experiments has been validated for the hardness based on input process parameters (welding current, welding voltage, travel speed, welding rod diameter). The findings from the study revealed that the most important factor influencing the hardness of creep-strength enhanced ferritic (CSEF) material welds is the voltage while other factors have minimum or the least influence for the studied ranges and factors.

Abstract: Ceramic cutting tools have a large potential by high speed processing of difficult-to-cut steels and alloys, however due to its fragility they don’t assure the required reliability level of cutting process. For improving the operational characteristics of the ceramic cutting tool combined treatment can be used namely the preliminary planetary grinding of the insert surface and the following deposition of the vacuum-plasma coatings (TiCr)N, (ZrCrHf)N and other.

Abstract: Objective: The purpose of this study was to investigate the transition temperature range (TTR) and the effect of temperatures at 10, 20, 30, 40, 50 and 60 °C on the deactivation force of three commercially available NiTi archwires. Materials and methods: Three different brands of NiTi archwires, NiTi OR (Ormco), NiTi GH (G&H) and NiTi H (Highland), with a cross sectional area of 0.016 x 0.022 inch² were analysed for transformation temperature range (TTR) by using differential scanning calorimeter and load-deflection characteristics using a three-point bending test at temperatures of 10, 20, 30, 37, 40, 50 and 60 °C. Statistical Analysis: Descriptive analysis was used to calculate each variable and Kruskal Wallis test was performed to assess the difference in measurements among the three NiTi wires. P<0.05 was considered as statistical significant. Results: TTR showed austenitic temperature finish (Af) at 24.45 °C for NiTi OR, 27.55 °C for NiTi GH and 51.5 °C for NiTi H. The highest deactivation force was found in NiTi H followed by NiTi OR and NiTi GH at the temperatures below and higher than 37°C. There were siginificant differences (p<0.05) in the deactivation force of NiTi OR - NiTi H and NiTi GH - NiTi H at 10 °C and 20 ^oC, and NiTi GH – NiTi H and NiTi GH – NiTi OR at 30 °C and 37 °C. However, no significant difference was found among all NiTi wires at 40, 50 and 60 ^oC, except NiTi GH – NiTi H at 60 ^oC. A close relationship was found between temperature and unloading curves (deactivaton force); increase in the temperature led to an increase in the plateau of delivery deactivation force and decrease in temperature led to a decrease in the plateau of delivery deactivation force. Conclusion: The TTRs of commercial NiTi archwires are variable, expecially the austenitic finish temperature. The deactivation force increases in higher temperature and decreases in lower temperature.

Abstract: Objectives: The aim of this study was to investigate and to compare the deactivation force, deactivation length and superelasticity in horizontal and vertical directions of Nickel-titanium (NiTi) orthodontic archwires made by 3 different manufactures. Materials and methods: The archwires tested were NiTi-OR (Ormco), NiTi-GH (G&H) and NiTi-H (Highland) and were 0.016 x 0.022 inch² in cross-section and 25 mm in length. The study analysed load-deflection curves from three-point bending tests performed for each type of NiTi wire in vertical (occluso-gingival) direction (0.022” in horizontal dimension) and horizontal (bucco-lingual) direction (0.016” in vertical dimension) at oral temperature (37±10 ^oC). Statistical Analysis: Descriptive analysis and Kruskal Wallis test were performed to assess differences in deactivation force, deactivation length and superelasticity among the three brands. A p<0.05 was considered as significant. Results: The deactivation forces ranked from low to high were NiTi-GH, NiTi-OR and NiTi-H, 2.09, 2.57 and 2.90 N, respectively in horizontal dimension (occluso-gingival direction) and 3.04, 3.54 and 3.62 N in vertical dimension (bucco-lingual direction), respectively. For the deactivation length, ranking from long to short were NiTi-GH, NiTi-OR and NiTi-H, 1.08, 1.02 and 0.63 mm in horizontal dimension and 1.63, 1.46 and 1.13 mm in vertical dimension, respectively. In regards to superelasticity, NiTi-OR showed the highest superelasticity, 15.37 in horizontal and 9.68 in vertical dimension, followed by NiTi-GH, 9.51 for horizontal and 6.40 for vertical dimension and NiTi-H, 4.12 for horizontal dimension and 2.96 for vertical dimension. Conclusion: Deactivation force was higher in vertical than horizontal dimension and deactivation length was longer in vertical than horizontal dimension. However, the superelasticity was higher in horizontal than vertical dimension, except NiTi-H. The high priced NiTi wire (NiTi-OR) had the most superelasticity following by medium (NiTi-GH) and low priced wires (NiTi H).