Papers by Keyword: Micrograph

Abstract: ST 41 steel is a low carbon steel which can be used for propeller shafts because it is categorized as a carbon steel permitted by BKI with a tensile strength requirement of 400 to 800 N/mm². The propeller shaft deteriorates due to its surface frequently rubbing against the bearings. Carburizing is a technique used to increase the surface hardness by heating the specimen in a closed container containing mixture of carbon and a catalyst. The main objective of the subsequent quenching and tempering processes is to increase toughness and ductility while eliminating residual stresses. The achieved results are based on tests conducted on ST 41 steel with a measured carbon layer thickness of 229.12 μm, namely coal carbon media. Based on the results of wear tests, coal carbon media possesses a minimum value of 6.38287E-05 mm²/kg. In torsional testing, the maximum shear stress value for carbon media made from coconut shell charcoal is 429.79 MPa. When measuring hardness, coal carbon media has the highest value, which is 340.918 VHN. And metallographic testing shows that pearlite is the main phase in coal carbon media. The media with the most carbon is coal carbon, which 0.729% on the surface of the steel. Keywords: St 41 Steel, Carburizing, Wear, Hardness, Torsion, Chemical Composition, Micrograph.

Abstract: Geophagists are generally defined by culture, social status and gender, and this paper is to identify the chemical elements of the geophagic material called Machu Rumi. The sample was extracted from the center of the geophagic material. Two micrographs were observed, the 1c micrograph contains: O (8.63%), Al (14.85%), SiO2 (33.07%), Fe (5.93%), K (5.36%), Mg (1.37 %) and Ca (0.81%), these elements are characteristics of the clay minerals, the 1d micrograph, contains: oxygen 62.14%, Silicon 37.80% and Aluminum 0.06%, these elements are present in the clay minerals soils. The results of elemental composition and micromorphology reveals the presence of phyllosilicates, SiO2, Fe, K, Mg, Ca, and Al so the consumption of Machu Rumi would contribute to the benefic geophagy.

Abstract: This study was conducted to investigate fatigue behavior of friction stir welding (FSW) butt joints for 6156-T6 aluminum alloy. The detail fatigue rating (DFR) values of 6156-T6 FSW joints is obtained based on statistical analysis of fatigue tests. The micrographs of weld structure were observed by optical microscope (OM), Fatigue fractography was researched under scanning electron microscope (SEM). The results indicate that DFR value of 6156-T6 FSW joints is 153.31MPa. Fatigue property of FSW butt joints is sensitive to the microstructural features, such as nugget zone (NZ), thermo mechanically affected zone (TMAZ) and heat affected zone (HAZ). The hardness distributions of the FSW joints reveal W-shaped profiles. Fractography shows that fatigue cracking is initiated at weak-bonding defects, which are located at the root site of the butt joint. The weak-bonding defects have obvious influence on the fatigue properties of friction stir welding.

Abstract: This article deals with the repair process of a gas turbine blade tip by impulse laser build-up welding, optimization algorithm for the technological process is proposed and macro-and micrograph of the investigated surface was made.

Abstract: The micrographs and optical properties of Al-doped ZnO (AZO) films deposited by radio frequency (RF) magnetron sputtering are presented in this paper. The AZO films termed as films I, II and III were sputtered on glass substrates heating at 300C, 400C and 500C, respectively. The micrographs, crystal structures and optical properties of AZO thin films were analyzed by using scanning electronic microscopy (SEM) images, X-ray diffraction (XRD) pattern, optical transmission and reflection spectra ranging from 350 to 1000 nm. As the substrate temperature increases to 500C, the film III exhibits a better flatness surface and a larger grain size of ~25nm with a stronger c-axis orientation. The film II has a high transmittance of greater than 92% in the visible light region. We also show that the films II and III have significant red-shift band gap ~3.00 and ~3.13eV, respectively, in comparison with that of the film I (3.31eV). This might be due to the increasing doped Al atoms which do not activate due to segregation at the grain boundaries.

Abstract: A novel material synthesis technique, microwave process was investigated for the production of phosphor powders. In this study, we have developed a new method to product phosphor powders, and applied this process into one materials fabrication. EuDL3 where L is cinnamic acid (C6H5CH = CHCOOH, HL), D = 2, 2' – Bipyridine (bipy) phosphor powders were successfully synthesized by microwave process. The process takes only 24 min to obtain phosphor powders. The resultant phosphor powders were investigated by TG – DTA, IR, luminescence spectroscopy, and scanning electron microscope (SEM).

Abstract: A novel material synthesis technique, microwave process was investigated for the production of phosphor powders. In this study, we have developed a new method to product phosphor powders, and applied this process into two materials fabrication. EuDL3 where L is cinnamic acid (C6H5CH = CHCOOH, HL), D = 2, 9-dimethyl-1, 10-phenantroline (dmp), or 2, 2'-bipyridine (bipy) phosphor powders were successfully synthesized by microwave process. The process takes only 24 min to obtain two phosphor powders. The process takes only 24 min to obtain two phosphor powders. The resultant phosphor powders were investigated by TG-DTA, IR, luminescence spectroscopy, and scanning electron microscope (SEM). The results revealed that the two materials is significant different, compared to micrographs of scanning electron microscope (SEM).

Abstract: Titanium alloy is a kind of typical difficult-to-machine materials. In this study, the surface integrity of titanium alloy Ti-6Al-4V machined by electrical discharge machining (EDM) method are experimentally investigated and analyzed in term of surface roughness, SEM micrographs and microcracks. Effect of discharge energy and material properties on surface integrity are presented in this paper.