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In this experimental work, AA7075-15 wt. % SiC (10–20 µm) composite was made through stirring casting. Experiments were performed on this composite by tungsten carbide cutting tools of different no...

Silicon carbide (SiC), Silicon nitride (Si3N4) particles were added in AA6082 to produce aluminum matrix composites (AMCs). Identifying suitable joining process and selecting appropriate parameters is essential for application of these AMCs. Fabricated plates of AA6082/SiC/5 wt.%, AA6082/SiC/10 wt.%, AA6082/SiC/15 wt.% and AA6082/Si3N4/5 wt.%, AA6082/Si3N4/10 wt.%, AA6082/Si3N4/15 wt.% composites were properly welded by friction stir welding (FSW). L9 orthogonal array of taguchi was utilised to design the experiments and optimize the parameters. Effects of tool rotation speed, welding speed, and tool tilt angle on hardness of weld nugget zone of AA6082/SiC composites and AA6082/Si3N4 composites were also investigated. Homogeneous spreading of SiC particles in addition to spherodization of silicon needles and their spreading through matrix were found to be dominant factors for property improvement in stirring zone. It was revealed that the hardness of FSW joints increases because of existence and pining effect of hard Si3N4 particles. It was detected that increase in micro hardness of weld nugget of AA6082/SiC composite was more, as compared to increase in micro hardness of AA6082/Si3N4 composites. Novelty of work is that FSW parameters have been optimized to successfully weld and achieve maximum hardness of AA6082/SiC and AA6082/Si3N4 composites. Findings of this research work will be utilized for FSW of components made of these composites, and to achieve maximum hardness of FSW joints. Such components will be utilized in aeroplanes, satellite, cars and ships.

Metal matrix composites (MMCs) possess high specific strengths and resistance to wear and deformation. Because of these properties, they are needed for automotive and aerospace uses. SiC-reinforced MMCs show good prospective for these uses, but their greater use is hindered by inadequate ductility and fabrication problems. These issues need to be resolved. AA7075 was provided with 10 wt.% and 15 wt.% SiC particle size of 10–20 μm and 20–40 μm by stir casting technique. Composite casting was fabricated. Samples were prepared from these castings. Samples were examined utilizing scanning electron microscopy (SEM) and energy-dispersive X-ray analyses (EDAX). SiC particle distribution and interaction with AA7075 matrix was studied. Change in hardness and tensile strength due to addition of different wt.% and particle size of SiC particles was also investigated. Microstructures of all four types of AA7075/SiCp composite exhibited uniform SiCp dispersal into AA7075. Hardness enhanced by 10.48% with rise of SiC reinforcement from 5 to 15%. Maximum improvement (9.67%) in tensile strength was seen with the addition of 10 wt.% SiC (10–20 μm) particles. AA7075/SiCp composites will be used in industrial applications requiring high tensile strength along with wear resistance.

Turning of 7075 Al alloy reinforced with SiC particulates was done on CNC machine by using tungsten carbide tools. Experimental were planned as per face centered central composite design (FCCCD). Response surface methodology (RSM) was utilized for modeling impact of parameters viz. cutting speed, feed, depth of cut and nose radius on responses viz. surface roughness and tool life. Single objective optimization for surface roughness and tool life was carried out. To obtain balance between surface roughness and tool life, a system for concurrent optimization of several objectives founded on an overall desirability function was utilized. Multi response optimization provided cutting speed of 90 m/min, feed of 0.15 mm/rev, depth of cut of 0.20 mm and nose radius of 0.68 mm. turning at these conditions will result in lowest surface roughness and maximum tool life. Which signify a satisfactory whole desirability. Components of AA7075/ SiC composite are being used in automobiles, ships, aero planes due to their high specific strength and wear resistance. Machining of AA7075/10 wt.% SiC (10-20 μm) composites is still a challenge due to poor surface roughness and high tool wear. Novelty of this work is that values of parameters to simultaneously achieve minimum surface roughness and maximum tool life was obtained by multi response optimization of process parameters. Very little research is available on this issue in literature.

Supplemental material, sj-docx-1-tdo-10.1177_00494755211056170 for Methotrexate in erythema nodosum leprosum: Pitfalls to avoid by Hitaishi Mehta, Tarun Narang, Sunil Dogra and Bhushan Kumar in Tropical Doctor

Background Idiopathic intracranial hypertension (IIH) is a disorder of unknown origin, characterized by features of raised intracranial pressure (ICP). Existing literature is inconclusive about the role of transcranial Doppler (TCD) in the management of IIH. Objective To study the TCD changes in IIH patients, pre- and post-cerebrospinal fluid (CSF) drainage. Materials and Methods This was a prospective study, conducted between July 2017 and December 2019, in a tertiary care referral center in South India. Sixteen consecutive patients, suspected to have IIH, underwent magnetic resonance imaging ofthe brain, a baseline TCD, and lumbar puncture with CSF drainage and pressure monitoring. Post-CSF drainage, TCD was repeated and mean flow velocities, peak systolic velocities, end-diastolic velocities, and pulsatility index (PI), in the middle cerebral artery (MCA), vertebral artery, and basilar artery (BA) were noted. Thirteen patients had elevated CSF pressure, and fulfilled the diagnostic criteria for IIH. These patients were included in the final analysis and pre- and post-CSF drainage TCD blood flow velocities and PI were compared. Results The mean age of study participants was 29.92 ± 6.92 years. There was a significant reduction in the cerebral flow velocities in bilateral MCA, after CSF drainage and normalization of ICP. Flow velocities in posterior circulation and PI in MCA, PCA, and BA showed an insignificant reduction. Two patients, who did not show any reduction in flow velocities after CSF drainage, developed optic atrophy on follow-up. Conclusion TCD-derived systolic blood flow velocities can be used in the management and follow-up of patients with IIH.

PurposeMechanical properties are highly sensitive to the microstructure, and these are indirectly related to solidification parameters and processing conditions. AA7075 possesses lightweight and excellent properties as structural material which can be optimized with SiCp addition and a good fabrication technique.Design/methodology/approach7000 series aluminium alloys exhibit the highest mechanical properties. They are used for high-strength structural applications such as aircraft parts and sporting goods. The desirable properties of these alloys are: low density, high stiffness, specific strength, good wear resistance and creep resistance. The focus of this work is to investigate the microstructure of composites formed by the dispersion of silicon carbide particles (SiC) into AA7075 by stir casting processes. 7075 Al alloy is reinforced with 10 and 15 wt.% SiCp of size 10–20 µm by stir casting process. The composites have been characterized by X-ray diffraction and scanning electron microscopy, differential thermal analysis and electron probe microscopic analysis.FindingsSiCp distribution and interaction with AA7075 matrix have been studied. AA7075/10 wt.%/SiCp (10–20 µm) and AA7075/15 wt.%/SiCp (10–20 µm) composites microstructure showed excellent SiCp distribution into AA7075 matrix. In addition, no evidence of secondary chemical reactions has been observed in X-ray diffraction and electron probe microscopic analysis.Originality/valueLittle experimental work has been reported so far about effect of addition of 10 and 15 wt.% SiCp of size (10–20 µm) on the microstructure of 7075 Al alloy fabricated by stir casting process. The present investigation has been carried out to study the microstructure and carry out XRD, DTA and EPMA analysis of 7075 Al alloy, 10 and 15 wt.% SiCp of size (10–20 µm) composite and detect the interfacial reactions with the objective to minimize the formation of Al4C3.

Machining experiments on 7075 Al alloy/10 wt% SiC (particle size 10–20 µm) have been conducted based on response surface methodology (RSM). Sequential approach using face-centred central composite ...

Femur bone is both strongest and longest bone in human body. This bone is contained linear elastic, isotropic and homogeneous material of calcium phosphate. It supports maximum weight of the body in between hip and knee joint during static loading condition. Femoral shaft fractures are common in both the young and elder people in India due to high accident rate and osteoporosis respectively. This major problem can be indirectly reduced by using locking compression plates which is most preferable now. The locking plate possess several advantages in fracture fixation, combining angular stability through use of locking screws with misalignment correction and fracture reduction into the plate through use of suitable screws. The mechanical analysis of different material which are suitable for femoral locking plate need to be workout, Because uniformity of stress transfer to the bone along with femoral locking plate is also important. As expected, stresses can be found at screw holes, nearest to the fracture site. This design modification can reduce the clearance of screw which results in permanent stability of femoral locking plate and the use of this different material will help us to find suitable biomaterial for femoral locking plate. Novelty of this research work is that the proposed design modification will substantially increase the fatigue life of the fixator, especially at screw holes nearest to the fracture region, where most fatigue fractures are known to occur and will consequently be function of greater fracture load

Purpose Sound microstructure components are necessary for reliability and safety; hence, these components are used in aircraft, satellite, automobiles and ships, where many commercial alloys are not suitable. The paper aims to discuss this issue. Design/methodology/approach AA6082/Si3N4 and AA6082/SiC composites were fabricated using the stir-casting process considering 5, 10 and 15 vol.% of reinforcement particles. Density and porosity of AA6082/Si3N4 and AA6082/SiC composites were calculated. Characterization was done using an X-ray (EDX) detector, attached to SEM. The effect of addition of Si3N4 and SiC particulates in the AA6082 was investigated. Findings Results showed that Si3N4 and SiC particulates had good wettability with AA6082 and were uniformly distributed in AA6082 matrix. No adverse effects of reactions were noticed in the microstructure of AA6082/Si3N4 and AA6082/SiC composites. Research limitations/implications AA6082 with more than 15 vol.% of Si3N4 and AA6082/SiC reinforcement particles do not find industrial application where high hardness and tensile strength are required. Practical implications Components made from AA6082/Si3N4 and AA6082/SiC composites find their application where high hardness with better tensile strength is required. Social implications Naturally and locally available materials are utilized for fabrication. Originality/value Little work is available in the literature on fabrication and characterization of AA6082/Si3N4 and AA6082/SiC composites. The authors have identified the process parameters at which proper fabrication is done and sound microstructure is obtained.

Weldability, microstructure evolution and tensile strength of an aluminium alloy (AA6082) and of two category of composites with AA6082 matrix reinforced with Si3N4 and SiC particles during friction stir welding (FSW) were investigated. 5, 10 and 15 weight percentage of reinforced particle were used in each category. FSW was carried out as per the parameters selected by Taguchi L-9 orthogonal Array. Microstructure of nugget region was investigated by scanning electron microscopy (SEM) and EDS analysis. Effect of tool rotational speed, welding speed and tool tilt angle on tensile strength was also investigated. The optimum parameters to get maximum ultimate tensile strength (UTS) for AA6082/SiC and AA6082/ Si3N4 composites were found out. On one hand, SiC particles are fractured thus fined due to intensive stirring action during FSW. On the other hand, the plastic flowing of material in the weld is benefit to eliminate microporocities existed in original base material. The highest tensile strength of 193 MPa was obtained for AA6082/15 wt% Si3N4 composite, at tool rotation speed of 1950 rpm at fixed welding speed of 40 mm/min and fixed tool tilt angle of 2°. Hard Si3N4 particles transfer their strength to the AA6082 matrix by their strengthening mechanism. This happens because of load transfer from Si3N4 particles to AA6082 matrix.

Many researchers are doing effort to investigate the effect of different particulates or fillers incorporated in the composite materials. In this investigation, the effect of the incorporation of different amounts of carbon black particulates on the mechanical performance of carbon fiber-reinforced epoxy composites has been studied. The carbon fiber-reinforced carbon black/epoxy hybrids were prepared with keeping constant weight fraction of carbon fiber and varying weight fraction of carbon black (0, 5, 10, and 15 wt%), using hand lay-up technique. After cure, the fabricated composite materials were cut and dimensioned into specimens as per the ASTM standards of testing and submitted to tensile, flexural, and impact tests. The microstructural characteristics and fracture surfaces of the composite were examined by scanning electron microscope (SEM). Increments of 65.78, 32.07, and 36.11% have been noticed in the tensile strength, flexural strength, and impact strength respectively for the hybrid composite (10 wt% carbon black) with respect to the conventional carbon fiber-reinforced epoxy composite. The experimental result has been validated with the numerical technique. This study represents that carbon black/epoxy composites reinforced with carbon fiber show higher mechanical performance than the conventional carbon fiber-reinforced epoxy matrix composites.