Papers by Keyword: SEM Analysis

Abstract: This study assesses the feasibility and effects of incorporating reclaimed asphalt pavement (RAP) into roller-compacted concrete (RCC) for pavement applications. Six RCC mixtures, incorporating varying RAP fractions (0% to 100% as volumetric substitutions of natural aggregates), were formulated and evaluated for their fresh, mechanical, and transport properties. Scanning electron microscopy (SEM) analysis was conducted on the RCC mixture containing 100% RAP. The results indicated a decrease in overall mechanical properties as RAP content increased, with 28-day compressive and split tensile strengths declining by 70% and 40%, respectively, in the case of full replacement. This decline in mechanical performance was accompanied by heightened porosity and sorptivity. Nevertheless, RCC mixtures with up to 60% RAP met pavement construction specifications. SEM micrographs revealed significant pore concentration, especially in the interfacial transition zone between RAP aggregates and the cementitious matrix, indicating poor adhesion between these RCC phases. Furthermore, empirical correlations were established to illustrate the influence of RAP content and increased porosity on RCC's mechanical properties and sorptivity. These correlations allow engineers to predict the characteristics of RCC for any RAP rate and provide insights into the impact of substituting natural aggregates with RAP on porosity and, consequently, RCC's hardened-state characteristics.

Abstract: Due to the combination of its numerous excellent mechanical qualities, the flexible iron has been used more and more since its invention in 1948. To develop significantly improved characteristics, the unnecessary investigation is being done. The most recent development in the field of flexible iron, or SG iron, is Austempererd malleable iron. At four different temperatures, two different types of spheroidal graphite (SG) cast iron samples with varying copper weight levels were austempered. The temperatures used for austempering were 200°C, 300°C, 350°C, and 400°C. As a component of the austempering time and temperature, the effect of the austempering process (i.e. time and temperature) on the mechanical characteristics of spheroidal graphite iron was investigated. The progress of spheroidal graphite iron's properties was significantly influenced by the pace of cooling and the extinguishing process. The organisation of different stages during isothermal change under varied austempering settings has also been the focus of XRD analysis. By using SEM, graphite morphology has been focused on. For this investigation, samples were obtained from the castings' focal point for XRD analysis. It was discovered that virtually always, it is possible to discriminate between the ferrite (110) and austenite (111) lines. The ferrite (110) line is growing with expanding austempering time and declining with increasing austempering temperature, whereas the highest power of the austenite (111) line is expanding with expanding temperature. Thus, very precise control of the interaction components (austempering duration and temperature) is required for austempering. The results showed that, when compared to other grades (N1) through the various austempering processes used in this evaluation, ADI containing the alloying component copper (grade N2) achieved crucial mechanical qualities.

Abstract: Wire Electrical Discharge Machining (WEDM) is a modern machining technique. WEDM is electro-thermal non-conventional machining processes follow to cut very hard materials. WEDM is non-traditional material cutting operation employed to machine complex geometries and shapes. The present paper attempts to study surface and sub-surface variations during WEDM of titanium grade 7 alloy with Brass wire coated with Zn. This paper presents experimental studies with varying three key process parameters viz. pulse ON time (TON), pulse OFF time (TOFF), peak current (IP). The investigation is focused on assessment of material removal rate, surface roughness as well as recast layer. Scanning electron Microscope (SEM) examinations are carried out on surface textures and are discussed in the article. The obtained results indicated that the stretched pulse time discharges more energy causes rough surface finish. The MRR is also strongly influenced by T_ON.

Abstract: Bulk Germanium monosulphide (GeS) alloy was synthesized using the usual melt-quenching technique. Its grains were used as the source material to deposit thin films by vacuum thermal evaporation. Thin-films samples were doped with 1, 2, and 3 at.% indium by thermal co-evaporation and annealed in a vacuum at temperatures 373, 473 and 550 K for an hour. Compositional, structural, and morphological properties of the bulk GeS alloy and its thin films were investigated by Energy Dispersive X-Ray Spectroscopy (EDS), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) techniques. The analyses verified the stoichiometry (GeS) of the starting material in the prepared thin films. They also revealed that the thin films under study are amorphous, homogeneous, without any cracks deposited uniformly on the glass substrate with thickness 650 to 700 nm.

Abstract: The present investigation considers an experimental study of wear analysis of Al-6061 HMMC with SiC_p & Graphite_p as a reinforcement & optimization of wear testing parameters based on the Taguchi technique coupled with Linear Regression analysis. A Linear Regression Equation obtained from regression analysis is used as a confirmation test, for the optimum testing parameters that are obtained to get the minimum wear rate and maximum Co-efficient of Friction of Al-6061 HMMC. The wear rate experiments are carried out by utilizing the combinations of tribological testing parameters based on the L9 Taguchi OA with four testing parameters of namely applied load, Speed, Track diameter and % of reinforcement. The three materials, Al-6061 HMMC are developed by reinforcing Al-6061 aluminium alloy with different (3, 5 & 7) % of weight fraction (SiC_p+Graphite_p), particulates of size (<30𝜇m) in an electric crucible melting furnace. It is observed that sliding velocity has a significant contribution in controlling the friction and wear behaviour of Al-6061 HMMC (SiC_p+Graphite_p). A confirmation test is carried out to verify the results obtained through the optimization technique. In addition to above tests, Scanning Electron Microscopy (SEM) analysis, Elemental Characterization can be achieved by using of EDAX (Energy Dispersive X-ray Spectroscope), Surface Roughness is performed on the specimens to study the uniform dispersion of particulate matter, along with hardness test.

Abstract: The paper deals with the determination of nano, microstructural, and micromechanical properties of cementitious materials surface with self-healing agent based on calcium carbonate precipitation (calcite). This was done by means of electron microscopy with elemental microanalysis and nanoindentation. These methods can define parameters of individual phases within cementitious materials, which are important for the development of micromechanical models. Bacillus pseudofirmus in combination with culture medium 235 was chosen as a self-healing agent. Our study provides information about micromechanical properties of crystals resulting from spontaneous crystallization from the culture medium and from crystallization caused by bacteria.

Abstract: In this work a new approach of analyzing epitaxial graphene layers on semi-insulating SiC through the gray-scale entropy of SEM images as a measure for the graphene inhomogeneity is demonstrated. Raman spectroscopy as a versatile and the standard tool for graphene characterization allows additionally the determination of the layer properties such as layer count, Fermi level, defect concentration and strain. It is shown that the gray-scale entropy correlates with the defect density derived from Raman measurements and thus can be used as an additional characterization technique with much higher resolution than the conventional Raman spectroscopy allows. As a consequence, the results are used to reflect the two-stepped growth itself and to conclude for advantageous growth conditions.

Abstract: To study the influences of the nanomaterial upon the microstructure of the interfacial transition region of mortar that prepared with a composite binder comprising nanomaterial and to clarify its effect on the compressive strength improvement, in this study, the compressive strength, SEM analysis and XRD analysis were estimated for mortar containing different amounts of ZrO₂, SiO_2, Al₂O₃ and CaCO₃ nanoparticles. Four different contents of each nanoparticles’ types were used as a partial replacement of cement with 1%, 1.5%, 3% and 5% by the weight of cement. Results manifested that the mortar compressive strength enhancement can be ascibed to the microstructure amelioration of the interfacial transition region. In addition, the XRD analysis and the SEM micrographs elucidated the formation of hydration compounds and the enhancement in bonding due to the existence of nanoparticles.

Abstract: Cracks affect the durability of concrete by increasing its permeability. Self-healing materials can begin repairing themselves immediately after creating a crack. This is a big advantage of self-healing materials. In this study, effect of self-healing agents based on calcium carbonate precipitation for concrete is monitored for three months. Bacillus pseudofirmus was chosen as a self-healing agent and was tested on old cement pastes. Calcium precipitation was analyzed by scanning electron microscope with Energy-dispersive X-ray spectroscopy. The effect of added spontaneous calcination, culture media, bacteria and Ca²⁺ was monitored.

Abstract: Friction surfacing is a solid-state coating technique process in which a mechtrode is rotated against the substrate under pressure, henceforth forming a coat on the substrate. This process not only can be used as coating process but it also provides flexibility in coating different materials as a revamp manufacturing process and it is suitable for getting excellent mechanical properties after the surfaced deposits. Bond strength is very good and these deposits are expected to serve better service life. The present work deals with mechtrode of SS-316, D3-tool steel and aa-2014 are coated on low carbon steel substrate by friction surfacing process and design of experiment were done by using taguchi L9 orthogonal array where the process parameters are mechtrode, rotational speed and traverse speed. The coating thickness, coating width and the SEM-microstructure analysis were studied.