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Magnesium metal matrix composites (MMMCs) have exceptional mechanical and metallurgical characteristics, which have drawn the interest of researchers across the world. In the present research study, an attempt has been made to fabricate WE43 magnesium (Mg) based nanocomposites using friction stir processing (FSP) after incorporating nano-titanium carbide (TiC) as a reinforcement. Further, the impact of different FSP variables such as transverse speeds (40 mm/min and 80 mm/min), and tool rotation speeds (900 rpm and 1800 rpm) over the metallurgical, wear, and mechanical performance has been studied. The large thermal energy generated by the rotating FSP tool gives rise to the mechanism of dynamic recrystallization and plastic deformation. This contributes to refining the microstructure and improvement in microhardness as per Hall–Patch relation—contributing to prominent grain size refinement and Orowan mechanism strengthening, due to the dispersion of reinforcement particulates. The outcome of the results depicts that the nanocomposite fabricated at a tool rotation speed of 1800 rpm and 80 mm/min transverse shows better mechanical and tribological characteristics than other developed composites and the base alloy. More specifically, the grain size was reduced nearly 12 times, microhardness was 2.58 times higher, and ultimate tensile strength (UTS) was 2.08 times higher when contrasted to the base alloy. Moreover, the unprocessed base material was characterized by an adhesive wear mechanism whereas the presence of scratches depicts the abrasive wear mechanism was dominant for WE43/TiC nanocomposite.

Malocclusions need to intercepted at an early developing stage to prevent severe disturbing outcomes. In all reported cases, Class II is one of the most common malocclusions that is seen which requires treatment using functional appliances as it presents with considerable difficulty in later stages. Twin block has the advantage of versatility of appliance designs and they meet a wide range of requirements for correction of various types of malocclusions for patients. The aim of this study is to include all modifications that could be incorporated in the appliance design to be customized to individual patients according to their need.

Reinforced magnesium metal matrix nanocomposites (MMMNCs) have piqued the interest of scientific community in recent years. Friction stir processing (FSP) is a known process to achieve the highest level of secondary phase nanocomposites distribution in the base monolithic matrix. In this study, an attempt has been made to synthesize magnesium base AZ61A/n-TiC nanocomposites using FSP and the influence of tool rotational speed on the metallurgical, mechanical, and tribological behavior of the developed composites has been studied. Microstructural examination shows that as tool rotational speed increases, high plastic deformation occurs and heat is generated along with the concomitant shattering impact of rotation, which consequently develops larger grains in the stir zone. However, this also provides thrusts resulting in uniform distribution of the nanoparticles in the base matrix. Microhardness and ultimate tensile strength of the developed nanocomposite were found to be significantly improved when contrasted with the base metal. Lower wear rate was observed for the composite developed at 800 rpm along with the abrasive type of wear mechanism.

High-temperature corrosion of coal-fired boiler parts such as water walls and superheated tubes poses a serious threat to the efficiency of the thermal power plant. To overcome this, numbers of cor...

In this present work, an effort has been applied to fabricated AZ61/TiC magnesium based metal matrix composite. The effect of tool transverse speed and specimen holding time after etchant application has been studied before final design and run of experiments. A set of zig-zag holes were prepared into the 200 mm × 100 mm × 6 mm thick AZ61A plate and compacted with TiC particles. A fixed three pass Friction stir processing (FSP) was performed out employing a fixed tool rotation speed of 850 rpm and varying tool transverse speed of 25 mm/min, 100 mm/min and 170 mm/min. Optical microscopy (OM) was used to study the grain refinement. The results indicate that for tool rotational speed of 850 rpm and transverse speed of 25 mm/min better grains were formed at stir zone (SZ) and poor grains were observed once the specimen analyzed after 25 min of etching.

The comparative study of weld joints between different stainless steel grades was conducted by fabricating a weld joint between SS316 – SS304, SS316 – SS202, and SS304 – SS202 respectively with a rotary friction welding technique. The objectives of this study is to find out the best suitable combination from the above selected materials with respect to comparison of tensile strength value and Vickers micro hardness value of welded joints of prepared samples. To analyze the welding strength, tensile strength, and Vickers micro-hardness test was conducted. The observation shows that the best combination for optimum outcome is SS316 – SS304. It shows tensile value of 3920 Kgf and Vickers hardness value of 278 Hv at the weld interface. It was found that the composition of the alloying elements of the above-mentioned materials affects weld ability.

Friction stir welding (FSW) is a welding technique for the solid-state that leads to production of high quality welds. Even the results are seen in materials which are difficult to weld like brass, aluminium, copper etc. The welding institute invented this technique in 1991. This technique leads to production of a high quality weld joint without actually melting the materials. This technique is environment friendly, is easily performed and fast. Moreover components formed from FSW can be used for a lot of industry applications. The purpose of this investigation is to discuss friction stir welding process with respect to effect of the process parameters. The study provides a summary of latest research advancements in FSW of similar and dissimilar materials. The main objective is to find out the common conclusion from the compiled literature.

Purpose In recent days, friction stir processing (FSP) has emerged as a pioneering approach for the manufacture of composites with enhanced mechanical and tribological properties. The present study aims to examine the impact of process parameters such as tool rotation speed and number of FSP pass on the AZ61A/TiC magnesium metal composite for responses such as hardness and wear resistance. Design/methodology/approach To minimize number of experimental runs, design of experiment was configured according to the response surface methodology using central composite design. Analysis of variance has been conducted to develop mathematical and empirical model for studying relationship between tool rotation and number of pass for responses such as microhardness and wear resistance. Microhardness was checked on vickers microhardness testing machine, and tribological behavior were examined on pin-on-disc using tribotester. Wear morphology was analyzed via scanning electron microscopy. Findings The responses were predicted using validated mathematical model, and contour plots were generated to study the interaction and influence of process parameters. Wear observations suggest that for the base magnesium alloy adhesive wear mechanism was dominating and for the developed nanocomposites, abrasive wear mechanism is a prominent factor. It was also observed that both the selected parameters significantly influenced the responses. Originality/value To the best of the authors’ knowledge, no prior work has been conducted with this material and preparation of composites with TiC nanoparticles. Furthermore, no mathematical models have been developed to predict the response values.

The aim of the current investigation is to evaluate the erosion-corrosion (E-C) performance of wire arc sprayed Ni-20Cr and Ni-5Al coatings on T22 and SA516 boiler steels in a real boiler environme...

Osteoarthritis (OA) is a non-inflammatory deteriorating debilitating state that bring about remarkable health and economic issues globally. Break down/deterioration of the articular cartilage (AC) is one of the pathologic characteristics of osteoarthritis (OA). Nanocomposite hydrogels (NCH) materials are evolving as a potential class of scaffolds for organ regeneration and tissue engineering. In recent years, innovative hydrogels specifically loaded with nanoparticles have been developed and synthesized with the goal of changing conventional cartilage treatments. The detailed development of a tailored nanocomposite hydrogels (NCH) material utilized for tissue engineering is presented in this review study. Also, the mechanical characteristics, particularly the tribological behavior, of these produced NCH have been highlighted. Large amounts of research and data on the hydrogel substance utilized in cartilage healing are summarized in the current review study. When determining future research gaps in the area of hydrogels for cartilage regeneration, such information will provide researchers an advantage to further develop NCH.

The ever-increasing demand for light weighted hard materials for transportation industries encouraged researchers to develop composites with excellent mechanical properties which can transform it into more economical and eco-friendly. Reinforcing the metals with carbonaceous nanomaterials are progressively in focus due to their excellent capability to inculcate and tailor the properties of MMCs. In the present research, a hybrid nanocomposite of MWCNT-Graphene-AZ31 Mg alloy has been developed by using variable tool rotation speeds with friction stir processing (FSP). Optimized reinforcement ratio of 1.6% vol. MWCNT and 0.3% vol. of graphene have been used with variable tool rotation speeds, whereas other processing parameters are kept constant. The developed specimens were investigated using standard testing equipment for evaluating and comparing the mechanical properties on the basis of the microstructure of the processing regions and their morphological analysis, according to the ASTM standards. The obtained results revealed an improvement of 19.72% in microhardness and 77.5% of compressive strength in comparison with the base metal AZ 31 Magnesium alloy, with a tool rotational speed of 1400 rpm. The values of tensile stress and percentage area reduction were recorded as less than that of the base metal matrix, but an increasing trend has been observed in the values of both with the improvement on rotational speeds of the tool. The effectual strengthening mechanisms are analyzed on the bases of SEM images and observed that discussed and found that grain refinement strengthening is the major contributor to the strength of the nanocomposite. Keywords: MMCs (Metal Matrix composites), Friction stir processing (FSP), Multi-walled carbon nanotubes (MWCNT), Graphene Nano Particulates (GNP), Stir Zone (SZ), Thermo-mechanically affected zone (TMAZ), Heat Affected Zone (HAZ)

In the current study, friction welding of two different steels, namely low alloy steel and austenitic stainless steel was done. For conducting welding, an in-house experimental set-up was designed and fabricated. The steels were friction welded by using various axial pressures at a uniform circular speed. Influence of axial pressure on the joint strength of the friction welded specimens such as tension, impact toughness, torsion strength and microhardness were evaluated. Moreover, the weldments were also tested for high temperature corrosion resistance. The corrosion testing of the welded joints was carried out in a molten salt environment of Na2SO4 + V2O5 60% at 650°C. Weight change data were used to establish the kinetics of corrosion. Based upon this data, the weldments showing best corrosion resistance was identified. Subsequently to understand the composition of oxide scale, the specimen was evaluated using SEM/EDS and X-ray diffraction techniques.

The premature failure of boiler tubes, especially in coal fired boilers poses serious threat to the efficiency of the Indian boilers. In coal fired thermal power plant boilers, hot corrosion and erosion is the primary reason behind downtime, which leads to huge economic losses. So the consolidated results of the various researchers working in the area of combating hot corrosion of boiler tubes, especially in context with Indian boilers (both actual and simulated environment) are presented in this article. These results help the researchers in selecting an appropriate and accurate coating material composition, coating process and parameters for a particular boiler steel to improve the life of boiler tubes. So, that, any unwanted damage of boiler tubes due to hot corrosion could be minimized.

ObjectiveThe outcome of transcatheter closure in ostium secundum atrial septal defects is determined by the morphology of the defects. Modified techniques such as balloon assistance, pulmonary vein deployment, left atrial roof technique, and so on are used for circumventing the anatomic complexities and increasing the success rates.MethodsWe planned a prospective study looking at the outcomes of transcatheter closure in secundum atrial septal defects with modified techniques in different anatomic complexities identified in transoesophageal echocardiography and their association with outcome of transcatheter closure.ResultsTranscatheter closure was successful in 295 out of 346 (82%) patients with modified techniques. Balloon-assisted technique offered a success rate of 87%. The mean defect size was 34.7±2.78 mm (95% confidence interval (CI) 30.67–43.1 mm) with success and 40.16±4.5 mm (95% CI 32.16–44.7) with failure (p = 0.02). The mean total septal length was 38.11±0.63 (95% CI 35.21–40.56 mm) with success and 42.54±0.34 (95% CI 38.79–43.21 mm) with failure. The defect to septal ratios were 0.82 and 0.94 in success and failure groups, respectively (p=0.02). However, the absence of a retro-aortic margin, septal aneurysm, and multiple defects did not affect the success rate. Deficient inferior vena caval margin, deficient posterior margin, and size⩾40 mm had a high risk of failure with transcatheter closure. The odds ratio for procedural failure was 25.3 (4.3–143.8) in patients with malaligned septum, 8.3(1.4–48.5) with deficient inferior vena caval margin, and 4.1(2.5–19) for size⩾40 mm.ConclusionsThe modified techniques for device deployment offer substantial chances of success in transcatheter closure of secundum atrial septal defects with anatomical complexity (82%). Variants such as defect size of⩾40 mm and deficient inferior and posterior margins have high failure rates with a modified technique.

In the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW) process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases with decreasing welding speed. Furthermore mechanical properties were also found to improve as the rotary speed increases and the same phenomenon was found to happen while using straight cylindrical threaded pin profile tool. The microstructure of the dissimilar joints revealed that at low welding speeds, the improved material mixing was observed. The similar phenomenon was found to happen at higher rotational speeds using straight cylindrical threaded tool.

The present study emphasizes on joints two industrially important materials AISI 304 with AISI 1021steels, produced by friction welding have been investigated. Samples were welded under different axial pressures ranging from 75MPa to 135MPa, at constant speed of 920rpm. The tensile strength, torsional strength, impact strength and micro hardness values of the weldments were determined and evaluated. Simultaneously the fractrography of the tensile tested specimens were carried out, so as to understand the failure analysis. It was observed that improved mechanical properties were noticed at higher axial pressures. Ductile failures of weldments were also observed at 120MPa and 135MPa axial pressures during fractography analysis.

Neurocysticercosis is an infection of the central nervous system caused by larvae of the pork tapeworm Taenia solium. We report a case of large cyst in the cerebellopontine angle that increased in size under observation and surgery revealed it to be cysticercus. It was removed in toto and patient improved on follow-up.

Spinal schwannomas are benign intradural extramedullary tumors arising from spinal nerve root sheath. They are usually solid or heterogeneously solid. Totally cystic schwannomas are rare entities. Herein, we report a 60-year-old male presenting with backache radiating along the chest wall and weakness of both lower limbs. He had spastic paraparesis. Magnetic resonance imaging revealed a cystic mass in the thoracic region. At operation, the cystic mass was seen to be attached to D4 dorsal rootlets. It was excised in toto and histopathology confirmed it to be a schwannoma. The relevant literature is reviewed.

Retained surgical sponge is an uncommon complication after laminectomy. A 67-year-old male presented with a discharging sinus in the cervical region following cervical laminectomy. Magnetic resonance imaging (MRI) revealed bilateral symmetrical lesions in the paraspinal area. Re-exploration revealed gauze pieces on either side under the muscle. Persistent discharging wound after surgery should arouse the possibility of a foreign body. Because of the rarity of bilateral lesions, the present case is being reported.

Present paper describes the mechanical properties of Stellite-6 coated AISI 316 L stainless steel. Specimens were coated using Detonation Gun thermal spray process, with different coating thicknesses of Stellite-6 ranging from 50 µm to 150 µm. Afterwards their properties like tensile strength, impact strength and micro hardness were evaluated on the basis of the results obtained from the experimentation. For comparison of substrate and coated material the graphs were plotted. The coated specimens exhibited superior impact strength and microhardness than that of the bare specimens, whereas the tensile strength of coated specimens decreased marginally with the increase in coating thickness.

In the present study an attempt was made to join austenitic stainless steel (AISI 304) with low alloy steel (AISI 1021) at five different rotational speeds ranging from 800 to 1600 rpm and at as many different axial pressures ranging from 75 MPa to 135 MPa and then determining the strength of the joint by means of tensile strength. Furthermore scanning electron microscope analysis was performed to evaluate the pattern of failure at the fractured locations, also the micro hardness was checked at the weld interface and at distances on either side of the weld joint to evaluate the effect of heat. The highest tensile strength achieved by the welded specimens was 1.8% higher than the AISI 1021 steel and the lowest tensile strength obtained was 20% lower than the parent AISI 1021.

Austenitic stainless steel and low alloy steels are extensively used in various automotive, aerospace, nuclear, chemical, and other general purpose applications. Joining of dissimilar metals is one of the challenging tasks and most essential need of the present-day industry. It has been observed that a wide range of dissimilar materials can be easily integrated by friction welding. The objectives of the present investigation were obtaining weldments between austenitic stainless steel (AISI 304) with low alloy steel (AISI 1021) and optimizing the friction welding parameters in order to establish the weld quality. In the present study, an experimental setup was designed in order to achieve friction welding of plastically deformed austenitic stainless steel and low alloy steel. AISI 304 and AISI 1021 steels were welded by friction welding using five different axial pressures at 1,430 rpm. The joining performances of friction-welded dissimilar joints were studied, and influences of these process parameters on the mechanical properties of the friction-welded joints were estimated. The joint strength was determined with tensile testing, and the fracture behavior was examined by scanning electron microscopy (SEM) and was supported and backed by energy dispersive spectroscopy (EDS) analysis. Furthermore, the proposed joints were tested for impact strength, and the microhardness across the joint was also evaluated.

In this present study an attempt was made to join austenitic stainless steel (AISI 304) with low alloy steel (AISI 1021) at different rotational speeds and at different axial pressures and then determining the strength of the joint by means of mechanical properties such as torsional strength, impact strength and micro hardness. The experimental results indicate that the rotational speed and the axial pressure have a significant effect on the mechanical properties of the joint and it is possible to improve the quality of the joint by selecting the optimum parameters.

In the present investigation, Ni 20Cr and Ni 5Al wires were used to deposit coatings on T22 and SA516 boiler steels for protection in high temperature environment. The microstructure, mechanical properties and high temperature oxidation behavior of the deposited coatings were studied. The coatings were found to have a uniform thickness (250–300 μm) and well intact with the substrate steels. The weight change study was conducted to ascertain the high temperature oxidation behavior of the coatings at 900 °C under laboratory conditions. The kinetics of oxidation was established using weight change values for the uncoated and the coated steels. The oxidation products of the coated and uncoated samples were analyzed using X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and X-ray mapping analysis. The results showed that Ni 20Cr coating on SA516 steel reduced the weight gain by 99%, whereas the Ni 5Al coating on T22 steel decreased weight gain by 83% than the bare steel. This higher oxidation resistance is due to the presence of a protective phases in the oxide scale (Cr2O3, NiCr2O4, NiO, and Al2O3), lower porosity (2%), and higher micro hardness of the coating.

Friction welding is widely used as a mass production method in various industries. In the present study, an experimental set-up was designed in order to achieve friction welding of plastically deformed AISI 1021 steels. In this study, low alloy steel (AISI 1021) was welded under different welding parameters and afterwards the mechanical properties such as tensile strength, impact strength and hardness were experimentally determined. On the basis of the results obtained from the experimentation, the graphs were plotted. It is the strength of welded joints, which is fundamental property to the service reliability of the weldments and hence present work was undertaken to study the influence of axial pressure and rotational speed in friction welded joints. Axial pressure and rotational speed are the two major parameters which can influence the strength and hence the mechanical properties of the friction welded joints. Thus the axial pressure and rotational speed were taken as welding parameters, which reflect the mechanical properties.

Joining of dissimilar metals is one of the most essential needs of industries. There are various welding methods that have been developed to obtain suitable joints in various applications. However, friction welding is a joining process that allows more materials and material combinations to be joined than with any other welding process. Continuous drive friction welding studies on austenitic stainless steel and ferritic steel combinations has been attempted in this investigation. Friction welding process parameter optimization, mechanical characterization and fracture behavior is the major contribution of the study. The microhardness across the weld interface was measured and the strength of the joint was determined with tensile tests and impact tests. Also the tensile fractured specimens were examined by scanning electron microscopy so as to study its fracture behavior. The experimental results indicate that axial pressure has a significant effect on the mechanical properties of the joint and it is possible to increase the quality of the welded joint by selecting the optimum axial pressures.

The objective of this study was to assess the affect of pallet location on torso kinematics during lifting. Participants transferred 11.3 kg boxes to pallets at two orientations and two distances from a constant lift origin. When reorienting the pallet from 180° to 90°, torso twist, lateral and sagittal torso kinematics increased when palletizing to various locations on the pallet when keeping the pallet distance far. Torso flexion increased slightly at the lowest level on the pallet independent of the pallet distance. When keeping the pallet distance close, torso twist kinematics decreased only when palletizing to the highest and closest position of the pallet. When reorienting the pallet from 180° to 90° adjacent to the lift origin, the best strategy to reduce torso kinematics appears to be to eliminate the transferring of loads to the lowest level of the pallet, and keeping the pallet close to the lift origin. © 2004 - IOS Press and the authors. All rights reserved.

Much of the intervention research for prevention of occupational low back injuries has focused on reduction of torso flexion and the external moment. Little is known about prevention strategies for torso twisting and lateral bending. It was hypothesized that increasing the distance between the lift origin and the pallet would require subjects to take an extra step, and reduce the torso kinematics and resulting LBD Risk. Fifteen males transferred 11.3 kg boxes from a constant origin to a destination pallet at two different distances. Analysis of Variance results indicated that increasing the pallet distance from the lift origin resulted in increases in velocities and accelerations, and the LBD risk at the lower regions of the pallet. These results suggest that increasing the pallet distance from the lifting origin does not appear to be an effective intervention strategy to reduce the risk of occupational LBD associated with torso kinematics.

The aim of the present study was to investigate the effect of axial pressures on the mechanical properties of friction welded AISI 304 with AISI 1021 steels, produced by mechanical joining. In the present study, an experimental setup was designed in order to accomplish friction welded joints between austenitic stainless steel and low alloy steel. Samples were welded under different axial pressures, at a constant speed of 800 rpm. The tensile strength, impact strength, and microhardness values of the welded joints were determined and evaluated and on the basis of the results obtained from the experimentation, the graphs were plotted.

Cystic glioblastoma multiforme (GBM) is a rare disease whose exact prevalence is unknown. Glioblastoma is usually seen as a unilateral solid tumor more commonly in the supratentorial compartment. The presence of cyst in the GBM is rare. Bilateral large cystic GBM is still rarer and we report such a case. An 83-year-old female was admitted with right hemiparesis and inability to speak for the last 4 days. There was no history of headache or seizures. On examination, there was increased tone on the right side with hemiparesis and aphasia. Magnetic resonance imaging revealed large enhancing cystic lesions measuring 4 × 2.8 × 3 cm and 4.5 × 4 × 3.5 cm in the right and left frontal regions respectively with surrounding edema [Figure 1]. Radiological possibilities suggested were glioma with differential diagnosis of abscess and metastasis. Burr-hole aspiration revealed hemorrhagic fluid and biopsy of the cyst wall confirmed the diagnosis of GBM. Attendants were explained the prognosis and did not give consent for definitive surgery. Patient died within 5 months of discharge from the hospital.

Two adults, 31 and 20 years of age, developed supratentorial metastasis 3½ years and 11 months, respectively, after gross total removal of their posterior fossa medulloblastoma. The first case developed spinal metastasis as well. Both had undergone craniospinal irradiation. Case 1 underwent laminectomy and case 2 underwent craniotomy because their presenting symptoms required so.