Evaluation of Tribological aspects of Al-Si 12 alloy and their Metal Matrix hybrid Composites produced by Liquid-metal Forging Method

Particulate Aluminium Metal Matrix Composites (Al-MMC) have emerged as advanced engineering materials in view of their improved properties. Ceramic reinforced Al-MMC were more suitable because of being economical and exhibiting isotropic properties. Al-MMCs manufacturing methods are expensive, demand skilled and complex operations and vortex liquid metallurgy results into higher porosity. The liquid-metal forging/squeezed casting of stirred molten slurry can eliminate porosity as molten metal is pressurized during solidification forming near net shapes. During many instances, influence of process parameter (PP)s on mechanical part properties is being studied. In the present study, composites were produced using Al-Si12 alloy as base material, aluminium oxide and silicon carbide particles as reinforcements by varying the PPs. Tribological tests were conducted under dry sliding condition at room temperature showed hard reinforcements in Al alloy reduced the wear rate (WR) and increased the coefficient of friction (f) for all PPs. For PPs, increasing the squeeze pressure and decreasing the pouring and die preheating temperature resulted in a reduction of WR and f with an increase in normal load and sliding velocity. Initially f falls and then raised with an increase in normal load, but only raised with growing sliding velocity compared to Aluminium base material.

Evaluation of Tribological aspects of Al-Si 12 alloy and their Metal Matrix hybrid Composites produced by Liquid-metal Forging Method

Particulate Aluminium Metal Matrix Composites (Al-MMC) have emerged as advanced engineering materials in view of their improved properties. Ceramic reinforced Al-MMC were more suitable because of being economical and exhibiting isotropic properties. Al-MMCs manufacturing methods are expensive, demand skilled and complex operations and vortex liquid metallurgy results into higher porosity. The liquid-metal forging/squeezed casting of stirred molten slurry can eliminate porosity as molten metal is pressurized during solidification forming near net shapes. During many instances, influence of process parameter (PP)s on mechanical part properties is being studied. In the present study, composites were produced using Al-Si12 alloy as base material, aluminium oxide and silicon carbide particles as reinforcements by varying the PPs. Tribological tests were conducted under dry sliding condition at room temperature showed hard reinforcements in Al alloy reduced the wear rate (WR) and increased the coefficient of friction (f) for all PPs. For PPs, increasing the squeeze pressure and decreasing the pouring and die preheating temperature resulted in a reduction of WR and f with an increase in normal load and sliding velocity. Initially f falls and then raised with an increase in normal load, but only raised with growing sliding velocity compared to Aluminium base material.

Synthesis and Characterization of Molybdenum Disulfide/Conducting Polymer Nanocomposite Materials for Supercapacitor Applications

The needs for energy storage devices have kindled researchers desire to explore and synthesize nanocomposite materials. Storing energy efficiently, effectively and sustainably are the science and engineering communities’ highest priorities to develop electrochemical energy storage devices. Supercapacitors have become power solution not only because supercapacitors can bridge the gap between the traditional capacitors and rechargeable batteries but also because of many other advantages which include extraordinary electrochemical properties, wide working-temperature range, cost effective, safe operation and long/stable cycle life. They have higher current pules than batteries due to the mechanism of charging and discharging. Batteries charging and discharging via chemical reactions, whereas supercapacitors utilize electrochemical double layer capacitors, in which nanoscopic charge separation is employed for energy storage at the electrode/electrolyte interface of the device. One of the key factors that determine the performance and properties of electrochemical capacitors is the electrode material. The performance of supercapacitor relies on features such as specific surface area, electronic conductivity as well as mechanical and chemical stability of the electrode materials. Using conventional electrode materials, it is challenging to address all critical features include: toxicity, low specific capacitance and energy density, poor cycle stability, high cost and self-discharge. One of most intensive approaches of overcoming these obstacles is by introducing and developing nanocomposite materials for supercapacitors. In this investigation, a MoS2/PEDOT nanocomposite material was chemically synthesized at various ratios of MoS2 to ethylenedioxythiophene (EDOT) to understand the charge mechanism in a symmetric supercapacitor. Whereas, previous attempts have been made to homogeneously cover MoS2 nanosheets with a PANI coating layer to obtain nanocomposite electrodes. However, emeraldine salt (ES) form of PANI is an insoluble polymer which may impede advantageous deposition techniques. Taking advantage of the processability of emeraldine base (EB) form of PANI, this approach can create an orderly distribution and homogeneous layer of PANI/N-Methyl-2-pyrrolidone (NMP) over MoS2 allowing the nanocomposite to coat over conducting substrates. The targeted nanocomposite material was finally de-doped to convert the PANI to ES, the conducting form, and enhanced the supercapacitor performance. Finally, after understanding the interesting combined effects of the material’s chemistry and capacitive properties in both two and three electrodes based electrochemical cells configuration and sponge based substrates was proposed for solid-state supercapacitor. The electrochemical deposition technique was applied, along with in-situ self-assembled polymerization of PPy and PANI, to fabricate the device. The morphological and crystal structures of the nanomaterials and nanocomposites of all projects were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size analyzer (PSA), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray-diffraction (XRD) techniques. In addition, the electrochemical properties of them were investigated to reveal their intriguing electrochemical and physicochemical properties using four-point probe, cyclic voltammetry (CV), constant current charging–discharging (CCCD), electrochemical impedance spectroscopy (EIS) in aqueous electrolytes. MoS2/PANI/PPy nanocomposite materials were considered for ideal supercapacitors which rendered highest specific capacitance around 631 F g-1. Owing to its superior electrochemical performance with the merits supercapacitors were produced for storing energy. This approach has revealed the possibility of using the natural or synthesized porous substrate to obtain a high surface area based supercapacitor

High specific capacitance solid state supercapacitor and method of manufacture

A novel electrode and associated method of manufacturing said novel electrode comprising a porous structure having absorbed polystyrene sulfonate (PSS), a self-assembled polypyrole (PPy) layer adjacent to the PSS absorbed porous structure, a self-assembled polyaniline (PANI) layer adjacent to the PPy layer, an electrochemically deposited PANI layer adjacent to the PPy layer and an electrochemically deposited PANI-molybdenum disulfide (PANI-MoS2) layer adjacent to the electrochemically deposited PANI layer. A supercapacitor and associated method of manufacturing a supercapacitor comprising a first novel electrode and a second novel electrode separated by a polyvinyl gel and a porous separator

High specific capacitance solid state supercapacitor and method of manufacture

A novel electrode and associated method of manufacturing said novel electrode comprising a porous structure having absorbed polystyrene sulfonate (PSS), a self-assembled polypyrole (PPy) layer adjacent to the PSS absorbed porous structure, a self-assembled polyaniline (PANI) layer adjacent to the PPy layer, an electrochemically deposited PANI layer adjacent to the PPy layer and an electrochemically deposited PANI-molybdenum disulfide (PANI-MoS2) layer adjacent to the electrochemically deposited PANI layer. A supercapacitor and associated method of manufacturing a supercapacitor comprising a first novel electrode and a second novel electrode separated by a polyvinyl gel and a porous separator

High specific capacitance solid state supercapacitor and method of manufacture

A novel electrode and associated method of manufacturing said novel electrode comprising a porous structure having absorbed polystyrene sulfonate (PSS), a self-assembled polypyrole (PPy) layer adjacent to the PSS absorbed porous structure, a self-assembled polyaniline (PANI) layer adjacent to the PPy layer, an electrochemically deposited PANI layer adjacent to the PPy layer and an electrochemically deposited PANI-molybdenum disulfide (PANI-MoS2) layer adjacent to the electrochemically deposited PANI layer. A supercapacitor and associated method of manufacturing a supercapacitor comprising a first novel electrode and a second novel electrode separated by a polyvinyl gel and a porous separator

Effect of a Rapid Tooling Technique in a 3D Printed Part for Developing an EDM Electrode

The role of rapid tooling (RT) in additive manufacturing (AM) seems essential in improving and spreading out the vista of manufacturing proficiency. In this article, attempts were made to discover the feasibility and the accomplishments of the RT electrode in the field of electro-discharge machining (EDM). Fused deposition modeling (FDM) is one of the AM processes adopted to fabricate the EDM electrode prototype by coating with copper. The copper is deposited on FDM-built ABS plastic component for about 1 mm through thick electroplating. The copper-coated FDM (CCF) and solid copper (SC) electrodes are used to conduct experiments on a die-sinking EDM machine using tool alloy steel as a workpiece. The CCF polymer electrode can be efficiently used in EDM operations as the build time of any complex shape was substantially reduced. However, the material removal rate (MRR) is far less than that of the SC electrode. It is recommended that the CCF electrode is used for semifinishing and finishing operations in which MRR happens to be less. However, CCF can get spoiled as high temperatures are generated on the machining tool, and the plastic core hardly sustains such high temperatures

Effect of part build orientations and sliding wear factors on tribological characteristics of FDM processed parts

Fused Deposition Modeling (FDM) components are commonly used for either prototypes or end products, mostly made of polymers. Polymers offer low frictional resistance to wear, so most of the engineering polymers find their increased usage in day-to-day industrial as well as domestic needs. The influence of many process controlling elements on the mechanical part properties is already being studied extensively, which demands the study of tribological characteristics like friction and wear rate under varying normal load (NL), sliding velocities (V) and part building orientations (PBO). The results showed a significant impact of the PBO and NL at various V on the tribological properties under various significant suitable sliding circumstances. Cracks were formed in the cylindrical tribometer specimens of Acrylonitrile butadiene styrene (ABS) fabricated at low PBO when operated at high NL, and V. Vertical PBO to the FDM building platform in the layers form where a number of inter-layers can bear maximum NL at higher values of V resulted in uniform wear and low frictions. Friction was noticed very low at minimum NL when PBO was 0° (horizontal) and 90° (vertical), but increased at high NL between PBO of 15° to 60°. The FDM parts improved compared to those from conventional manufacturing processes

High-Temperature Corrosion of APS- and HVOF-Coated Nickel-Based Super Alloy under Air Oxidation and Melted Salt Domains

Various thermal spraying approaches, such as air/atmospheric plasma spraying (APS) and high-velocity oxy-fuel (HVOF) spraying, are widely employed by plants owing to their flexibility, low costs and the high surface quality of the manufactured product. This study focuses on the corrosion behavior of a Ni superalloy coated with powder Cr3C2-25NiCr through APS and HVOF at 950 °C under air oxidation and Na2SO4 + 0.6V2O5 molten salt environments (MSE). The results show that HVOF-deposited Ni superalloys have higher hardness and bond strength than the respective APS coating. The thermo-gravimetric probe reveals that the Ni superalloys exposed to an oxidizing air environment has a minor mass gain compared to those under the MSE domain for both non-coated and coated samples, in line with the parabola curvature rate oxidizing law. The Ni superalloys show good corrosion resistance but poor oxidation resistance in APS-deposited Ni superalloys under the MSE. HVOF-coated Ni superalloys in both environments exhibit better corrosion resistance and lower mass gain than APS-coated superalloys. The excellent coating characteristics of HVOF-coated Ni superalloys lead to their better high-temperature corrosion performance than APS

Assessment of the Corrosion Behavior of Friction-Stir-Welded Dissimilar Aluminum Alloys

The fuel consumption of high-density automobiles has increased in recent years. Aluminum (Al) alloy is a suitable material for weight reduction in vehicles with high ductility and low weight. To address environmental problems in aircraft and maritime applications, in particular rust development and corrosion, the current study assesses the corrosion behavior during friction stir welding (FSW) of two dissimilar Al alloys (AA6061 and AA8011) in various corrosive conditions using salt spraying and submersion tests. Two acidic solutions and one alkaline solution are used in these tests, which are performed at room temperature. The two specimens (AA6061 and AA8011) and the weld region are suspended in a salt spraying chamber and a 5 wt.% NaCl solution is continually sprayed using the circulation pump for 60 h, with the specimens being weighed every 15 h to determine the corrosion rates. According to the salt spraying data, the weld zone has a higher corrosion resistance than the core components. For twenty-eight days, individual specimens are submerged in 3.5 wt.% HCl + H2O and H2SO4 + H2O solutions and seawater. The weld area specimens exhibit stronger corrosion resistance than the base material specimens, and weight loss in the saltwater medium is lower when compared to the other test solutions, according to the corrosion analysis. The scanning electron microscope (SEM) analysis demonstrates that the base metal AA8011 is considerably corroded on its surface