Wear Studies on Metal Matrix Composites: a Taguchi Approach

1. IntroductionDiscontinuously reinforced aluminium metal matrixcomposites (DRAMMCs) are a class of composite materi-als, which have desirable properties including low density,high specific stiffness, high specific strength, controlledco-efficient of thermal expansion, increased fatigue re-sistance, superior dimensional stability at elevated tem-peratures etc[1]. The most commonly employed metalmatrix composite system consists of aluminium alloy re-inforced with hard ceramic particles usuall…     

Predictive modelling of dry sliding wear in sealed plasma-sprayed Mo coating using response surface methodology

Plasma spraying is used to produce wear resistant coatings. However, the primary problem is the poor bonding strength between the coating and the substrate. The secondary problem is the high porosity in the as-sprayed coatings, which reduces the wear resistance of coating. In order to overcome these problems, the sealing of plasma-sprayed coating by electrodeposition has been used. The sealing of plasma-sprayed coatings alters the wear mechanism and wear resistance. The wear mechanism and wear resistance largely depends on the applied load, sliding speed and sliding distance. Hence, an effort has been made in the present work to study the effects of these parameters on wear volume loss using response surface methodology (RSM)-based mathematical models. The experiments were conducted as per Central Composite Design (CCD). It reveals that the applied load was the most predominant factor affecting the wear volume loss of the coating material. The sliding speed is the next most important parameter influencing the wear volume loss. The wear volume loss of the sealed plasma-sprayed molybdenum coating occurs mainly due to the formation of grooves, surface tribo films, fracture of splats and delamination of the coating.     

Chemically reactive and radiative flow of ferro-aluminum (AA7075) hybrid nanofluid past a stretching cylinder

The present investigation throws light on the heat transfer behavior of hybridized (ferro-aluminum alloy [AA7075]) nanofluid. In addition to that, influences of thermal radiation, magnetic effect, and chemical reaction are also considered for the exploration. Here, the flow is deliberated due to a porous stretching cylinder. The equations that portray the fluid flow are transfused to simple ordinary differential equations by applying similarity elements. Then, the procured equations have been solved by adopting the Runge–Kutta–Fehlberg 4th–5th order tool. The extracted solution are exported to plot graphs for velocity, thermal, and solutal profiles with the concerned parameters, and using these plots, the discussion has been produced for the behavior of all flow fields. The behavior of the thermal profile shows substantial enhancement with an increase in the solid volume fraction of hybrid nanofluid. The velocity and concentration panel de-escalates for larger values of Reynolds number. A significant discussion on the skin friction drag, Nusselt number, and Sherwood number has been produced.     

Drilling of hybrid metal matrix composites—Workpiece surface integrity

The main concern in the present study is the surface roughness variations on the drilled surface and extension of surface and sub-surface deformation due to drilling. The influence of different tools and cutting conditions on Al2219/15%SiCp and Al2219/15%SiCp-3%Graphite (hybrid) composites is investigated experimentally. The composites are fabricated by liquid metallurgy method. The drilling tests are conducted with carbide and coated carbide tools. The surface roughness decreases with the increase in cutting speed and increases with the increase in feed rate. The surface is analyzed using scanning electron microscope (SEM). Microhardness profiles indicate that the subsurface deformation extends up to a maximum of 120 μm below the machined surface for Al2219/15SiCp-3Gr composite when compared to 150 μm in Al2219/15SiCp composite.     

Identification of intracranial haemorrhage (ICH) using ResNet with data augmentation using CycleGAN and ICH segmentation using SegAN

Multimedia Tools and Applications - Intracranial Haemorrhage (ICH) occurring due to any injury to the brain is a fatal condition and its timely diagnosis is critically important. In this work, we...     

Dry sliding wear characteristics of glass–epoxy composite filled with silicon carbide and graphite particles

The dry sliding wear characteristics of a glass–epoxy (G–E) composite, filled with both silicon carbide (SiC_p) and graphite (Gr), were studied using a pin-on-disc test apparatus. The specific wear rate was determined as a function of sliding velocity, applied load and sliding distance. The laminates were fabricated by the hand lay-up technique. The volume percentage of filler materials in the composite was varied, silicon carbide was varied from 5 to 10% whereas graphite was kept constant at 5%. The excellent wear resistance was obtained with glass–epoxy containing fillers. The transfer film formed on the counter surface was confirmed to be effective in improving the wear characteristics of filled G–E composites. The influence of applied load is more on specific wear rate compared to the other two wear parameters. The worn surfaces of composites were examined with scanning electron microscopy (SEM) to investigate the probable wear mechanisms. It was found that in the early stage of wear, the fillers contribution is significant. The process of transfer film, debris formation and fiber breakage accounts for the wear at much later stages.     

Collapse Mechanism of Foam Cored Sandwich Structures Under Compressive Load

In this work the moisture absorption capability, compressive properties, collapse modes of various types of composite sandwich structures are reported. The tested sandwich structures were constructed with varieties of hybridized skin materials and different compositions of the core materials. The moisture absorption, Flatwise compression and Edgewise compression tests are conducted for core as well as sandwich structures. Comparisons of results have been between the hybridized and non-hybridized sandwich structures. Two modes of collapse were noticed in the Edgewise compressive test, one of which being progressive end-crushing of the sandwich structure featured by significant crash energy absorption. This feature was highly desired for the parts of transportation vehicles. Microscopic analysis has been carried out to know the nature of failure under compressive loads. It has been observed that with increasing the debonding strength of the core–face interface, the failure mode changes from unstable collapse mode stable progressive crushing.     

Two-phase Sakiadis flow of a nanoliquid with nonlinear Boussinesq approximation and Brownian motion past a vertical plate: Koo-Kleinstreuer-Li model

This paper investigates the Sakiadis flow of a Al₂O₃-H₂O nanoliquid with consistently scattered dust particles over a vertical plate. To account for the effect of the Brownian movement, the Koo-Kleinstreuer-Li model is considered. In some thermal systems such as reactor safety areas, and solar collectors, combustion works from moderate to high temperature, making the relationship between the temperature and density nonlinear. To consider this temperature-dependent density, the nonlinear Boussinesq estimation is utilized. The present physical structure, which includes energy and momentum equations, is converted into a system of ordinary, coupled, and nonlinear differential conditions through the help of similarity transformations. By using the finite difference code, the subsequent equations have been numerically solved. The impact on the velocity and the thermal profiles of the nondimensional parameters is visualized through graphs. Both the Nusselt number and friction factor strengthen with a higher nonlinear thermal parameter in the case of nonlinear Boussinesq approximation compared to the linear Boussinesq case. Growing estimations of nonlinear thermal parameter deteriorate the thermal profile but it boosts the velocity profile of both liquid and dust phases.     

Characterization of Laser Remelted Plasma-Sprayed Mo Coating on AISI 1020 Steel

Plasma-sprayed molybdenum (Mo) coating was deposited on an AISI 1020 steel substrate. Laser remelting was used to eliminate the open pores and microcracks of the plasma-sprayed molybdenum coating. The quantitative investigation of porosity was carried out with the help of Biovis image analysis software. The microhardness was measured using a Vickers indenter. The influence of laser remelting on the wear volume loss of plasma-sprayed Mo was estimated by using a pin-on-disc wear test rig. The worn surface was characterized by scanning electron microscopy. The experimental results demonstrate that the porosity of the coating was decreased and microhardness was improved by laser remelting. The laser remelted plasma-sprayed Mo coating exhibits better wear resistance compared to the untreated plasma-sprayed Mo coating. It is concluded that laser remelting is a potential treatment for the plasma-sprayed coating. In this study, the laser remelted plasma-sprayed Mo coating exhibited of lowest porosity, higher hardness and better wear resistance.     

Combustion characteristics of a 4-stroke CI engine operated on Honge oil,Neem and Rice Bran oils when directly injected and dual fuelled with producer gas induction

Energy is an essential requirement for economic and social development of any country. Sky rocketing of petroleum fuel costs in present day has led to growing interest in alternative fuels like vegetable oils, alcoholic fuels, CNG, LPG, Producer gas, biogas in order to provide a suitable substitute to diesel for a compression ignition (CI) engine. The vegetable oils present a very promising alternative fuel to diesel oil since they are renewable, biodegradable and clean burning fuel having similar properties as that of diesel. They offer almost same power output with slightly lower thermal efficiency due to their lower energy content compared to diesel. Utilization of producer gas in CI engine on dual fuel mode provides an effective approach towards conservation of diesel fuel. Gasification involves conversion of solid biomass into combustible gases which completes combustion in a CI engines. Hence the producer gas can act as promising alternative fuel and it has high octane number (100–105) and calorific value (5–6 MJ/Nm³). Because of its simpler structure with low carbon content results in substantial reduction of exhaust emission. Downdraft moving bed gasifier coupled with compression ignition engine are a good choice for moderate quantities of available mass up to 500 kW of electrical power. Hence bio-derived gas and vegetable liquids appear more attractive in view of their friendly environmental nature. Experiments have been conducted on a single cylinder, four-stroke, direct injection, water-cooled CI engine operated in single fuel mode using Honge, Neem and Rice Bran oils. In dual fuel mode combinations of Producer gas and three oils were used at different injection timings and injection pressures.Dual fuel mode of operation resulted in poor performance at all the loads when compared with single fuel mode at all injection timings tested. However, the brake thermal efficiency is improved marginally when the injection timing was advanced. Decreased smoke, NO_x emissions and increased CO emissions were observed for dual fuel mode for all the fuel combinations compared to single fuel operation.