International Journal of Microstructure and Materials Properties (19 papers in press)
CRACKING PERCEPTION OF MACHINE COMPONENTS WITH SOUND EMISSION DURING STEEL QUENCHING
by Franc Ravnik, Janez Grum
Abstract: Quenching and tempering often represent a stage near the end of the manufacturing process ofrnmachine components. The purpose of selecting the most suitable quenching parameters andrncontrolling the hardening process is to ensure the required hardness and the residual stresses,rnparticularly in the surface layer of a machine part. This is most important in mass production,rnin which the best mechanical properties are required in order to obtain the lowest cost and thernbest quality. This paper includes the investigation of certain acoustic events during steelrnquenching. The possibility of understanding the relation between a connection between soundrnemission with the wetting kinematic of the quenching agent and a hot specimen with otherrnphenomena during quenching was examined. It was determined that the captured acousticrnsignals could identify the suitability, i.e. the quality of the quenching process to ensure betterrncontrol of the quenching process. For this purpose, a system with a hydrophone was designedrnto capture acoustic emissions. An investigation of sound emission was carried out with a fewrncylindrical specimens, i.e. different shapes made of heat-treatable steel quenched in quenchingrnagents with different cooling severities. Furthermore, the possibility of acoustic signals causedrnby workpiece deformation and crack formation due to high internal stresses were examined. Arncomparison of results shows that this possibility can lead to an applicability approach torncontrolling the hardening process and quality of steel parts.
Keywords: cooling rate; cracking; nucleate boiling; sound emission; quenching.
Analysis on the Effect of Pressure and Mass Fraction of Chromium to Mechanical Properties and Electrical Conductivity of Copper-Chromium Composite in Hot Compaction Process
by Dicki Nizar Zulfika, Widyastuti Widyastuti, Lukman Noerochim, Nanda Hendra Pratama, Subardi Marjali, Irwin Maulana, Radyum Ikono, Nurul Taufiqu Rochman
Abstract: Cu-Cr composite is used in the electronic industry as a material which is directly connected to the electricity, as a component of a circuit breaker, cable contact, circuit board, etc. In this study, hot compaction method was employed to manufacture Cu-Cr composite which has an excellent hardness and electrical conductivity. Composite manufacturing was based on powder metallurgy technique while mixing used mechanical milling method in regards to its better homogeneity. Hot compaction process set at the temperature of 300 oC was applied to the powder material to increase the plasticity so the compaction can be done easier. Some variation were made on the composition of Cu:Cr ratio (90:10, 80:20, 70:30, and 60:40), and the compaction pressure (500, 700, and 1000 MPa). Sintering was conducted at 850 oC with holding time of 1 h. Based on the results, the optimum sintering density of 96.81% of its theoretical density was obtained at Cu:Cr ratio as of 80:20. Maximum hardness at 60%Cu:40%Cr and P= 1000 MPa was 129 VHN. And, electrical conductivity was reached its optimum value of 82.6% IACS when the Cu:Cr ratio was 90:10 at P= 1000 MPa.
Keywords: Cu-Cr; Hot Compaction; Composite; Powder Metallurgy.
Research on hysteretic behavior of high-strength concrete shear wall plate for steel tube in building construction
by Zhongwei Liu
Abstract: For the problem of insufficient analysis of the hysteretic behavior of the traditional concrete shear wall, the research method of hysteretic behavior of high-strength concrete shear wall for steel tube in building construction is proposed in paper.Based on the OpenSee platform,the displacement of the base was recorded by the displacement meter installed on the base, and the load displacement curve is plotted, and the shear bearing capacity of the model was analyzed. The failure modes, axial compression ratio and concrete strength parameters of the specimens were studied to obtain the following conclusions. Higher the axial compression ratio and the wall shaft pressure, the higher the load capacity of the specimen. By comparing the hysteretic behavior of different steel tube high strength concrete shear strength specimens, this paper analyzes the performance of steel tube high strength concrete shear wall panels, which provides data and reference for future construction.
Keywords: Building construction; steel tube; high-strength concrete; shear wall; hysteretic behavior.
Characterization of LM6/cenosphere composites
by Tanusree Bera, Samir Kumar Acharya, Goutam Sutradhar
Abstract: In this work, the LM6/cenosphere composites were fabricated by the squeeze casting. The various weight percentages of cenosphere (wt. % c/s) (5, 7.5, 10, 12.5, and 15) wt. % c/s were selected for the synthesis of the LM6/composites. The characterization of the reinforced and unreinforced composites through SEM, XRD, and EDX analysis was carried out. The mechanical properties (hardness, and tensile strength) were investigated. The optical properties were investigated through FTIR and UV-VIS-NIR. The results revealed that the reinforced LM6/cenosphere composites show better mechanical properties than the unreinforced composites. The 15 wt. % composites show the improved hardness and tensile strength with minimum porosity as compared with other reinforced composites. The XRD analyzed the various phases of the materials. The EDX analyzed the atomic and the wt. % of reinforced elements exists in the LM6/cenosphere composites. The SEM analyzed the tensile fractured surfaces of the reinforced and unreinforced composites.
Keywords: LM6 alloy; Cenosphere; Squeeze casting; Mechanical properties,Fractography; Optical properties; X-rays Diffraction; Scanning electron microscope.
Parametric Optimization of Gas Metal Arc Dissimilar Welding on AISI 304 Stainless Steel and Low Carbon Steel
by Taiwo Abioye, Chibueze Kanu, Tunde Ogedengbe, Damilola Adebiyi
Abstract: The weld-bead geometry and mechanical properties of the AISI 304 stainless steel and low carbon steel gas metal arc dissimilar weldments were optimized within a process window (wire feed rate (66-96 mm/s), voltage (19-25 V) and welding speed (3-6 mm/s)). The variations of the weld-bead width and mechanical properties with the processing parameters were analyzed and presented. Significant changes in the microstructure of the weld zone with the heat energy inputs were observed. All the three utilized parameters contributed significantly to the bead width, ultimate tensile strength and hardness of the weldments. The welding speed contributed most significantly to the ultimate tensile strength and bead width while the voltage has the most significant effect on the hardness. Optimum weld qualities including continuous joint, high tensile strength (422 MPa) and high hardness (112 HB) were found at 84 mm/s wire feed rate, voltage of 25 V and speed of 3 mm/s.
Keywords: Gas metal arc welding; Optimization; Dissimilar metals; Full factorial design; ANOVA; Mechanical properties; AISI 304 stainless steel; Low carbon steel; Microstructure; Heat energy input.
Contribution to thermal study of modified cement pastes based on siliceous SCMs.
by KARIMA ARROUDJ, Mohamed Nadjib OUDJIT, Arezki TAGNIT-HAMOU
Abstract: This study aims to highlight siliceous additions available in Algeria : ground blast furnace slag
Keywords: Pozzolanic activity; Portlandite; Hydration degrees; DTA/TG; SEM; XRD.
WATER ABSORPTION BEHAVIOUR AND ITS EFFECT ON THE MECHANICAL PROPERTIES OF Gigantochloa scortechinii (BULUH SIMANTAN)
by Abeer Adel Salih
Abstract: This study aims to investigate the effect of short-term exposure of water to the mechanical properties of simantan fibres at different heights. Few studies have investigated the mechanical properties of raw natural fibres after water absorption. Bamboo culms were cut at 15 cm above the ground level and then subdivided into bottom, middle and top parts according to their total length. The raw fibres were immersed in distilled water at room temperature for different time durations (6, 24, 48, 72, 96, 168, 336, 504 and 672 h). Tensile, flexural and impact properties were examined before and after water absorption, the tensile fracture of raw fibres were observed by scanning electron microscopy, and the structure properties of raw fibres were examined by Fourier transform-infrared spectroscopy. The result showed that 6 h of immersion time exhibited the best tensile strength and modulus, showing 13.6% and 28% improvement compared with the dry condition. The optimum flexural strength and modulus were 240 MPa and 13.7 GPa, respectively, for the top part under dry condition. The impact strength for the bottom part after 672 h of immersion in water was 212 KJ/m2, which was very close to that under dry condition. SEM revealed that the main destruction is due to the lack of uniform breakage of fibres due to blanks and water absorption. Overall results clearly showed that immersion in water for a short time minimally affected tensile strength, modulus and flexural modulus but considerably influenced flexural strength and impact properties.
Keywords: microstructure; material properties; water absorption; bamboo fibres; natural fibres; mechanical properties; buluh simantan; bamboo culms; uniform breakage of fibres.
Microstructure Assessment of Bi-modal Microcellular Polymeric Composites developed using Multi-Stage Depressurization Technique in Solid-State Foaming Technology
by Abhishek Gandhi, Rajesh Panda
Abstract: In this study, bimodal microcellular acrylonitrile butadiene styrene foams have been manufactured through solid-state batch foaming process using two staged gas depressurization technique. After blowing agent saturation, the thermodynamic instability induction on polymer/gas system due to instantaneous pressure drop was performed at two distinct depressurization stages. Each stage corresponded to nucleation of discrete cell morphology in the polymer matrix. This article puts forward a study to understand the fundamental mechanism behind bi-modal cell nucleation phenomenon. Further, Influence of holding time, holding pressure, foaming temperature and foaming time on the foam morphological attributes was studied. By altering the process parameters, the morphological attributes in the final product could be controlled efficiently.
Keywords: microcellular; microstructure; morphology; bimodal; foam; cells; composite.
Characterization of self-healing efficiency of calcium nitrate microcapsules for concrete applications
by Ala Abutaqa, Mohammed Al-Ansari, Ahmed Senouci, Marwa Hassan, Ahmed Shaat, Mohamad Mohsen
Abstract: This study presents characterisation of concrete samples containing 0.75% by cement weight of modified calcium nitrate self-healing microcapsules. The phased array ultrasonic testing method was used to investigate the healing efficiency of calcium nitrate microcapsules in concrete. The method is a novel non-destructive testing technique that is commonly used for detecting the defects in welding. Concrete beams were prepared from the control mix (without microcapsules) and mixes containing 0.75% by weight of cement of calcium nitrate microcapsules. After 28 days of moist curing, the phased array ultrasonic images of all beams were captured before loading, after applying 60% of the ultimate flexural load, and after 3 and 7 days of accelerated healing. Moreover, scanning electron microscopy images taken from fractured surfaces of the beams that were loaded up to failure before healing were compared to those of the beams that were healed for 7 days and loaded up to failure
Keywords: Calcium nitrate microcapsules; self-healing concrete; calcium nitrate microcapsules; phased array ultrasonic testing; scanning Electron Microscopy.
Effect of Duty Cycle on Microstructure, Composition and Ablation Resistance of Tungsten-Cobalt Coatings Prepared by Electrodeposition
by Haipeng LU, Junqi QIN, Changchun DI
Abstract: Tungsten-cobalt coatings with different tungsten contents were prepared on the surfaces of PCrNi3MoVA steels by electrodeposition at different duty cycles. Scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD) were used to analyze the effect of duty cycle on the microstructure and composition of the surface and cross-section of tungsten-cobalt coatings before and after ablation. The ablation performance was measured using a self-developed semi-closed explosive ablation tester. The results show that the CoW phase mainly exists in the tungsten-cobalt coating before the ablation. The tungsten content in the coating increases first and then decreases with the increase of the duty cycle. When the duty cycle is 30%, the tungsten content is the highest (43.37wt%). The grain size increases with the increase of the duty cycle. The grain size of the coating obtained at the 10% duty cycle is the smallest (9.70 nm); The tungsten-cobalt coating mainly contains CoW, WO3, CoO, SiO2, Fe3O4 and a small amount of CoWO4 phase after the ablation. The sample prepared at the duty cycle of 30% has the best ablation resistance, and its relative mass ablation rate and relative line ablation rate are 0.08% and 0.89%, respectively. The effect of duty cycle on ablation resistance of the tungsten-cobalt coating is mainly achieved by affecting the tungsten content and the grain size in the coating. Higher tungsten content and denser crystal, the ablation resistance of tungsten-cobalt coating is better . The ablative mechanism of the tungsten-cobalt coating is a combination of thermal chemical ablation of tungsten-cobalt coating oxidation, thermal physical ablation of melting and evaporation of oxidation products, and mechanical ablation of high-temperature and high-pressure propellant gas.
Keywords: Pulse electrodeposition; Tungsten-Cobalt coating; Duty cycle; Tungsten content; Ablative properties.
Structural, optical and galvanomagnetical properties of low cost synthesized nanostructure Cu2S films
by Abdelfatah Mansour, Emad El-Menyawy
Abstract: The cu2s powder was prepared by low-cost hydrothermal method and was deposited as thin films by thermal evaporation. The structural properties are explored by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The XRD shows a monoclinic polycrystalline nature of hydrothermally prepared powder, while the deposited film shows a hump corresponding to Cu2S nanocrystallites. HRTEM micrograph shows nanoparticles with sizes ranging from 30 to 45 nm. Based on the thermogravimetric results, the thermal kinetic parameters are calculated by application of Broido method. The optical energy band gap of the evaporated films is determined as 2.3 eV. The electrical conductivity, charge carriers concentration, carriers mobility and the magnetoresistance (MR) of the films are investigated as a function of temperature.
Keywords: Copper sulfides; Hydrothermal; Thermogravimetric; Optical; Galvanomagnetic; Conductivity; Carriers concentration; Mobility; Magnetoresistance.
SYNTHESIS AND CHARACTERISATION OF Sb-DOPED ZrO2 AND TiO2 NANOPARTICLES
by ASHA PAI
Abstract: The present study aims at the synthesis and structural characterisation of Sb-Doped Titania and Zirconia nanoparticles using a modified precipitation synthesis method. The produced nanoparticles were characterised using various techniques such as UV-Visible spectroscopy, Scanning electron microscopy, Transmission electron microscopy and Dynamic light scattering. The crystallite sizes were obtained to be <20 nm for Sb-Doped ZrO2 and <10 nm for Sb-Doped TiO2 which was very evident from the Transmission electron microscope images. The hydrodynamic sizes in the range of 100 nm using Dynamic light scattering method were also evaluated for the assessment for biological application. The optical band gap was found out to be 3.21 eV for Sb-Doped TiO2 and 3.87 eV for Sb-doped ZrO2.
Keywords: Zirconia; Titania; X-ray diffraction; Doping; precipitation synthesis; Transmission electron microscopy; Scanning electron microscopy; dynamic light scattering.
Vegetable Oil Quenchants: A Review
by Rosa L. Simencio Otero, Lemmy Meekisho, Lauralice C.F. Canale, George E. Totten
Abstract: For thousands of years, vegetable oils have been used as cooling media to heat treat metals. However, the motivation for employing quenchants formulated with biodegradable, non-toxic and renewable base stocks has seen significant increase due to the environmental appeal to replace petroleum based quenchants. This paper presents an overview of the main aspects and characteristics of vegetable oils that directly influence their commercial application such as structure, classification, biodegradability and toxicity, quenching properties, oxidation and inhibition, and wetting. Further, some applications of vegetable oils as quenchants will be discussed here.
Keywords: Quenching; Heat Treating; Heat Transfer; Vegetable Oil; Triglycerides; Hardening.
Surface Morphology Analysis of AISI-D3 Tool Steel Using Rotary Tool Electric Discharge Machining Process.
by Anand Prakash Dwivedi, Sounak Kumar Choudhury
Abstract: Electric Discharge Machining is one of the most prominent machining processes, which is used across the world for machining and creating intricate shapes in very hard-to-cut electrically conducting materials.
This comprehensive study aims to investigate the surface modification and characterization of thin AISI-D3 tool steel sheets and provides a thorough information about the material characteristics, which are quite vital from the design and reliability point of view.
The analysis shows that the average improvement in the final surface finish of the machined surface is close to 12%. In addition, the energy dispersive spectroscopy images confirm the presence of 2.1% copper and 25.22% of carbon on the workpiece surface, showing the tool material transfer at the workpiece surface. Moreover, the scanning electron microscope images confirm the presence of a thinner recast layer, fewer micro-cracks and very less embedding of tool material on the workpiece surface as compared to the stationary tool process.
Keywords: Electric Discharge Machining (EDM); Energy Dispersive Spectroscopy (EDS);
Scanning Electron Microscope (SEM); Micro-cracks; Recast layer.
Determination of temperature-dependent Youngs modulus of Bulk Metallic Glass
by Suresh Kaluvan, Haifeng Zhang, Sanghita Mridha, Sundeep Mukherjee
Abstract: Bulk metallic glasses are fully amorphous multi-component alloys with homogeneous and isotropic structure down to the atomic scale. Some attractive attributes of bulk metallic glasses include high strength and hardness as well as excellent corrosion and wear resistance. However, there are few reports and limited understanding of their mechanical properties at elevated temperatures. We have used two methods in this paper to determine the Youngs modulus of a bulk metallic glass, Zr41.2Ti13.8Cu12.5Ni10Be22.5 at elevated temperatures: sonic resonance method and nanoindentation. In the sonic resonance method, the measurement system was designed using a laser displacement sensor to detect the sonic vibration produced by a speaker on the specimen in high-temperature furnace. The OMICRON Bode-100 Vector Network Analyzer was used to sweep the frequency and its output was connected to the speaker which vibrated the material in its flexural mode. A Polytec OFV-505 laser vibrometer sensor was used to capture the vibration of the material at various frequencies. The flexural mode frequency shift due to the temperature variation was used to determine the Youngs modulus. The temperature range of measurement was from 50
Keywords: Metallic glass; Young’s Modulus; Nondestructive test; Sonic resonance; Elevated Temperature; Flexural mode vibration.
Study of Crystal-Amorphous Phase Transition and Morphologies of Metal Nanoparticle Fe under Annealing
by Kien Pham Huu
Abstract: The present work investigates the crystal-amorphous phase transition and morphologies of metal nanoparticles Fe (NPs) using means of molecular dynamics (MD) simulation. Tracing the number of crystal atoms and the analysis of radial distribution functions, we found that the amorphous Fe NP is transformed into bcc crystal one when it was annealed for long times at 900K. At the early stage of the annealing, small nuclei form in different places of NP and dissolve for short times. After long times some nuclei form and gather nearby which creates the stable clusters in the core of NP and to spread into the surface of NP. Based on the mean potential energy per atom analysis and MD data visualization technique, the effect of B atoms that prevent the growth of crystallization as well as the different morphologies of Fe and FeB NPs have been investigated in detail.
Keywords: phase transition; annealing; morphologies; crystallization; amorphous.
Analysis of Influence of Ultra-hydrophilicity of Oxidation Titanium Surface on Blood Compatibility Based on Density Functional Theory
by Qiongjian Huang
Abstract: Based on the density functional theory, it adopts the first-principles method to calculate the ultra-hydrophilicity of oxidation titanium surface under different oxygen vacancy concentrations. The calculation results show that under the practically feasible oxygen vacancy concentration range, with the increase of the oxygen vacancy concentration, the ultra-hydrophilicity of oxidation titanium surface is increased, and the semiconductor type of the oxidation titanium is transformed from p type to n type. When the oxidation titanium surface is in contact with blood, the n-type semiconductor and the features of the electron state occupying the bottom of conduction band of the oxidation titanium surface can suppress the transfer of charge from the fibrinogen in the blood to the oxidation titanium surface so to suppress the aggregation and activation of blood platelet, thus improve the ultra-hydrophilicity of oxidation titanium surface on blood compatibility.
Keywords: Oxidation Titanium;Oxygen Vacancy; Electronic Structure; Blood Compatibility.
Structural, optical and electrical properties of CuBiS2 thin films deposited by spray pyrolysis at different deposition times
by Abdelfatah Mansour, Islam Elradaf
Abstract: Reproducible and good quality copper bismuth sulfide (CuBiS2) thin layer were situated on preheated glassy slide substrates made implementing the spraying pyrolysis approach at distinctive times of spraying 15, 30, 45, and 60 min with a fixed substrate temperature 400 oC. The effect of spray time on the structural, morphology, optical and electrical benefits of the CuBiS2 thin films produced by spray pyrolysis methodology were studied. The structure was studied by XRD methodology. The surface texture of the produced films was considered by SEM. The optical benefits of the CuBiS2 films were inquired working with the spectrophotometric method in which the optical transmittance and reflectance beyond a wavelength range 200-2500 nm were measured. The d.c. conductivity was studied at different temperatures for all the prepared CuBiS2 thin films.
Keywords: Copper bismuth sulfide; Spray pyrolysis; Optical; Band gap; Electrical.
Modelling and Simulation of a Bending Process for S34MnV Steel
by Zhiqiang Hu, Kaikun Wang, Yan Yang
Abstract: To investigate the hot deformation behavior of S34MnV steel, hot compression tests in different deformation conditions were done. According to the experimental data, a constitutive equation was established and a mathematical model for dynamic recrystallization was established to predict the volume fraction of dynamic recrystallization. To reveal the plastic deformation, the bending process for a large S34MnV marine crank was simulated by Deform-3D. The stress and strain field of the bending process was obtained and analyzed based on the simulation. Finally, to study the effect of the bending process on the crank, a bending process of a crank produced with a hydropress in the factory was studied. The microstructure and mechanical properties in three different positions of the bending crank were analyzed. It was concluded that the bending process would reduce the uniformity of the microstructure and mechanical properties, owing to the nonuniformity of the deformation.
Keywords: Hot Deformation Behavior; Modelling and Simulation ; Bending Process.