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This study investigates the effect of ZrO2 reinforcement (5, 10 and 15) vol.% on the dry sliding wear behaviour of AZ31 Mg alloy composites produced using stir casting. The wear test (pin on disc) was conducted at different loads of (10, 20, 30 and 40) N and sliding velocities of (1, 3 and 5) m/s. The variation in the wear rate and friction co-efficient with the change in the load at a constant sliding distance was determined. Results showed that the composites exhibited a lower wear rate at higher loads and speeds compared to the AZ31 alloy. In particular, AZ31-15 vol.% ZrO2 composite showed the lowest wear rate and friction coefficient. Different wear mechanisms operating during the wear test were investigated using SEM and XRD.

NiCr metal is deposited on martensitic stainless steel using an atmospheric plasma spray method. To enrich the metallurgical properties of the NiCr metallic coating, a standard heat treatment process is adopted. From the investigation, it has been shown that the voids and porosity developed during the thermal spray have been controlled through heat treatment. Electron image analysis reveals that the coating has reduced porosity with strong and dense bonding strength. With reference to the surface hardness, the post-processed coating yields a maximum of 140 Hv compared with the coated (129 Hv) and base metal (115 Hv). Subsequently, the sliding wear behaviour of post-processed NiCr coating has a minimum wear of 25 μm for an applied load of 5 N and 57 μm for an applied load of 15 N. Owing to the high metallurgical bonding, the coating has sustained the heavy loads, and the wear formation is controlled. However, the base metal has an adhesive wear mechanism caused by the high frictional force on the sliding friction. Therefore, it is recommended that post-processed thermal barrier coatings possess good metallurgical bonding and withstand heavy load causing minimum wear.

In this research article, a leftover of Cymbopogon flexuosus stem (CFS) collected from the oil extraction industry was examined for its ability as a reinforcing agent in a polymer composite. Anatomical, morphological, physical, chemical, mechanical, and thermal characteristics of the CFS fiber were examined. Chemical analysis revealed the presence of higher amount of cellulose (68.13%), which offers better bonding properties and higher tensile strength (431.19 ± 23.96 MPa). Moreover, the density of the fiber (1270 kg/m3) found using physical analysis was less than that of synthetic fibers, which paves a path in replacing hazardous synthetic fiber. Solid-state nuclear magnetic resonance and Fourier transform infrared spectrum spectroscopy analyses were conducted to study the functional groups of the extracted CFS fiber. The thermal stability (253.17°C), activation energy (73.01 kJ/mol), and maximum degradation temperature (345.08°C) were investigated by thermogravimetric analysis. X-ray diffraction analysis confirmed the semi-crystalline nature of the fiber with crystallinity index (46.02%) and crystallite size (13.96 nm). The CFS had a smooth surface, as conformed by an atomic force microscopy and scanning electron microscope analysis. Altogether, this study highlights the feasibility of leftover CFS fiber residue as reinforcement in biopolymer matrices replacing synthetic fiber.

The study presents an analysis specifically on the effect of tool traverse speed (one of the most influential process parameters of friction stir processing) on the microstructural evolution, micro...

In this paper, a composite material is developed through fused deposition model (FDM). The E – glass fibre is used impregnate in the polylactic acid (PLA) plastic as a composite. The material is developed as per the ASTM standard for mechanical testing. The layer thickness (mm), feed speed (mm/min) and the extruder temperature (°C) are the three main input process parameters used to develop the composite material. The samples developed are ensured to standard dimensions before investigation on mechanical testing. Fusion temperature and layer thickness are the two main input process parameters for making FDM samples. With a minimum layer (0.1 mm) and maximum extruder temperature (201 °C) the FDM processed sample found increased strength. Decrease in temperature cause weak bonding and lead to failure.

The effect of thermal treatment on microstructure and tribological behavior of Al-7Si/ZrSiO4 reinforced composites has been investigated. Composites with 5, 10 and 15 vol.% of ZrSiO4 particles were produced using stir casting process. Produced composite samples were then further subjected to T6 heat-treatment by subjecting the cast samples for solution treatment for 4 h at 540 °C followed quenching in water and artificial ageing at 170 °C for 5 h. Microstructure of the composite samples revealed uniform distribution of ZrSiO4 particles. Hardness of the T6 thermal treated samples was found to be superior to that of Al-7Si alloy and hardness of the composite samples increased with increase in wt.% of ZrSiO4 particles. Non heat treated alloy and composite reinforced with 15 wt% of ZrSiO4 possessed a maximum hardness of 68 BHN and 110 BHN respectively. Whereas T6 heat treated Al-7Si alloy and composite reinforced with 15 wt% of ZrSiO4 exhibited a maximum hardness of 84 BHN and 146 BHN respectively. T6 treated composites exhibited superior resistance to wear, when compared to the base alloy. As cast Al-7Si alloy exhibited maximum wear rate of 14.3 × 10−3 mm3/m, where as non heat treated 15 wt.% ZrSiO4 reinforced composites exhibited a wear rate of 7.6 × 10−3 mm3/m and wear rate was found to further reduce to 4.0 × 10−3 mm3/m by T6 treatment. SEM images of the wear tested samples showed the adhesive wear and abrasive wear as the dominant wear mechanisms.

In the current study, friction stir processing was applied as a methodology to produce surface composites of AZ91D magnesium alloy with ZrO2 particles. Microstructural evolution, microhardn...

One of the different and pioneering solid-state techniques, friction stir processing (FSP), is employed for the production of surface composites. In this research, the matrix selected was copper-nickel (CuNi) with hard boron carbide particle as reinforcement. The objective of the current research work is to produce reinforced 90/10 copper-nickel surface composites reinforced with B4C fabricated via FSP. The influence of tool rotational speed on macrostructure, microstructure, grain size analysis, microhardness, and wear studies of friction stir processed (FSPed) CuNi/B4C surface composites was assessed. For high rotational speed (1400 rpm) of stir tool, the modified surface area found is a maximum of 44.4 mm2 with uniform dispersion of hard particle reinforcement. The presence of hard particle in the surface area is revealed through the electron imaging and the spectroscopic results. Spectra mapping shows the uniform distribution of hard particle over the FSPed area, and the evidence is obtained with XRD analysis. From the experimentation, it is interesting to report that the reinforcements have decreased the surface hardness for an increased rotational speed of stir tool. The hardness recorded for minimum rotational speed is 223 HV which has gradually decreased to 178 HV for 1300 rpm. It has directly influenced the wear rate of modified FSPed, as hardness is directly proportional to wear behavior. The worn surface and fractured morphology of the CuNi/B4C surface composites were also studied using Field Emission Scanning Electron Microscope (FESEM).

Aluminium alloy AA7075 matrix composites reinforced with different vol.% of niobium carbide were fabricated by friction stir processing. Microstructural investigations of the composites as well as the interface between AA7075 and NbC were conducted using optical microscopy and scanning electron microscopy. SEM micrographs revealed a homogeneous dispersion of NbC in the AA7075 matrix in all the composites. SEM studies also revealed very good bonding of the dispersoid particles with the matrix along with significant degree of grain refinement. Hardness and wear resistance of AA7075 matrix was enhanced both by the addition of NbC particles as well as grain refinement. Wear behaviour studies showed that predominant wear mechanisms were abrasive wear and adhesive wear.

Aluminium alloy AA7075 matrix composites reinforced with varying vol% (5, 10 and 15 vol%) of niobium carbide (NbC) were fabricated by friction stir processing. Micrographs revealed that a homogeneous dispersion of NbC in the AA7075 matrix had no interfacial reaction. Significant degree of grain refinement was observed in the composites due to dynamic recrystallization and pinning effect of NbC particles. Hardness and tensile strength of AA7075 matrix were found to be enhanced by the addition of NbC particles. The fracture surface of the tensile-tested samples revealed deep dimples indicating a good ductility.

Friction stir processing is applied to fabricate magnesium alloy AZ91D surface composite reinforced with nanophase Al2O3 particles. The refined microstructure in the developed surface composite is induced by nanophase Al2O3 particles and recovery–recrystallization phenomenon by friction stir processing. The results of electrochemical corrosion test and immersion corrosion test reveal that the corrosion rate of the developed surface composite decreased in simulated body fluids. The study originally reports that the homogeneous dispersion of nanophase Al2O3 particles and formation of an adherent layer of corrosion products (calcium hydroxyapatite and calcium-magnesium phosphate) in the developed surface composite decrease the corrosion rate. Besides, the formation of these corrosion products that mimic the bone matrix would support bone growth and promote integration of implant bone.

The large-scale generation of electric power using solar energy stimulates the development of novel technologies by researchers with ultimate resource qualities. Solar energy collectors are the significant part of Solar Energy Thermal Power Plant (STP), which can be operated at a particular feasible range for utilizing the solar resource with its intermittent inputs. The life span of solar thermal power plant can be increased by designing the controller with a closed loop. The proposed hybrid design of solar plant involves a controller with closed loop transferring the solar energy to the heat transfer liquid, namely therminol oil, which acts as a medium for transferring heat in Parabolic Trough Collector (PTC) having single-phase flow. The concentrators are the parabolic reflectors focusing the rays on the line with a focal point using tracking mechanism having one axis. Solar collectors are utilized in the power converting technique of solar thermal energy, which concentrates sunlight for preparing Rankine cycle heat of high temperature. The steam turbine is driven by the superheated vapor using Rankine cycle with the shaft of the steam turbine connected to the generator for producing electricity. The life span of the Solar Energy Thermal Power Plant is enhanced as proposed design for solar collectors uses therminol oil as the heat transfer liquid. The controller design is implemented using Predictive Function Control (PFC) or Static Feed Forward (SFF) control with Proportional Integral Controller (PI) which provides the best performance with the added advantage of direct heat storage in the thermal plant. The simulated results are obtained for the proposed design of collector with the rate of change of variation and cost function of manipulated parameters, which are constant for the proposed controller but vary drastically for the conventional PI controller.