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Coating by thermal spray method has proved to be the widely used and most economic way for developing coatings on various different materials in order for achieving all the needed material characteristics. Protective Coatings are most broadly and preferably produced and experimentally tested for various industrial areas namely automobile industry, thermal power plants etc. D-gun sprayed coating method can really be considered as unique coating method well known for producing coatings with very dense microstructure, low porosity, stronger and Erosion-corrosion resistant coatings. In this present study work Al2O3-13%TiO2 and Al2O3-40%TiO2 Coatings were deposited over ASTM 316 Boiler tube Steel with D-Gun spraying method. Various different methods namely X-Ray diffraction (XRD), SEM and X-Ray Mapping were used to characterize both the above mentioned coatings. After the investigation it was found that both of these coatings which we wanted to establish have been successfully established.

The erosion behavior of three different cermet coatings namely, Al2O3, Al2O3 + 3% TiO2 and Al2O3 + 13% TiO2 was studied in order to perform erosion analysis. The coatings were sprayed using Plasma spray gun in a simulated coal-fired boiler conditions on SAE-347H steel. An optical profilometer was put to use in order to find weight loss, erosion profiles and erosion rate (mm3/g) in term of volume loss. All the Plasma gun sprayed cermet coatings were able to protect SAE-347H steel from erosive wear at incident angles of 30°, 60° and 90°. In case of uncoated SAE-347H steel specimens the solid particle erosion (SPE) rate was highest at an incident angle of 30°, nominal at incident angle of 60° and lowest at incident angle of 90°.

The U-type hexaferrites, (Ba1-3xBi2x)4Zn2Fe36O60 where x = 0.05, 0.10, 0.15 and 0.20 were prepared via auto combustion technique. The structural properties were carried out by X-ray diffraction (XRD) studies. The room temperature magnetic properties were reported to increase with doping. Natio-Suetake model has been employed to calculate the reflection loss using transmission line theory. the maximum microwave absorption of 99.8% and −10 dB reflection loss has been obtained for the sample x = 0.20. This material can be used for the effective electromagnetic interference shielding (EMI) and reduction of radar signatures.

Power plants, gas power turbines and chemical based plants face a very big issue of accelerated type of corrosion i.e hot corrosion, because of which the lifespan of metal decreased to large extent. In the present investigation, S-304 steel was taken which is commonly used in thermal power plants for inspection of accelerated corrosion i.e hot corrosion and high temp. oxidation behaviour. Alumina plus 13% titanium(Al2O3 + 13%TiO2), Alumina plus 3% titanium (Al2O3 + 3%TiO2) , Alumina(Al2O3)powder was applied on the boiler steel samples by using plasma spraying process. The uncoated and coated samples were exposed for 50 cycles to cyclic high temperature oxidation in air at 900 °C and hot corrosion in molten salt conditions of sodium sulphate and vanadium oxide (Na2SO4 – 60% V2O5) at 900 °C. In Oxidation study, with weight gain of 1.86% the upmost resistance against oxidation was exhibited by Alumina plus 13% titanium coated(Al2O3 + 13%TiO2) followed by Alumina plus 3% titanium coated (Al2O3 + 3%TiO2) with weight gain of 2.36% and by 2.92% by Alumina coated(Al2O3). The least resistance was shown by bare S-304 with weight gain of 3.91%.In investigation of hot corrosion, the weight gain percentages of Alumina plus 13% titanium coated(Al2O3 + 13%TiO2) is 2.46%, Alumina plus 3% titanium coated (Al2O3 + 3%TiO2) coated is 2.92%, Alumina coated(Al2O3) is 3.77% and for uncoated its 4.67%. The outcomes obtained for protection against oxidation and hot corrosion is: plus 13% titanium (Al2O3 + 13%TiO2) > Alumina plus 3% titanium (Al2O3 + 3%TiO2) coated > Alumina(Al2O3) > uncoated S-304 boiler steel.

In the present investigation, a plasma spray process was used to deposit bi-layer NiCrAlY/ Al2O3-40%TiO2 coating powder on three substrates namely T-91, A-1 boiler steel, and Superfer800H superalloy. The deposited coating was found to be dense, and uniform with thickness ranges from 200 to 250 µm. The oxidation behavior of both (bare and coated) specimens at elevated temperatures was ascertained by using a high-temperature furnace. The experiments were conducted over 50 cycles. In each cycle, the specimens were subjected to an isothermal temperature of 900 °C for 1 h followed by cooling for 20 min at room temperature in atmospheric air. The thermogravimetric study for both (bare and coated) specimens was conducted to find the corrosion rate by calculating the parabolic rate constant of the corroded specimens. The characterizations of the coatings before and after the high- temperature oxidation tests were investigated by employing various characterizations techniques. The result showed that the Al2O3-40%TiO2 ceramic coating significantly reduced the weight gain compared with the bare substrates. The high resistance of the deposited coating against the harsh oxidizing environment was because of the occurrence of protective phase (Al2O3, TiO2, and Al2Ti7O15) in the oxide scale.

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...

Background Paroxysmal sympathetic hyperactivity (PSH) is an understudied complication of traumatic brain injury (TBI). PSH usually presents with transient rise in sympathetic outflow, leading to increased blood pressure, heart rate, temperature, respiratory rate, sweating, and posturing activity. We retrospectively analyzed the incidence of PSH in TBI using PSH-assessment measure (PSH-AM) scale. Methods This single-center retrospective cohort study was conducted in traumatic head injury patients admitted in the intensive care unit from January 1, 2016 to December 31, 2019 in a tertiary care center. The data was collected from the hospital database after obtaining approval from the hospital ethics committee. Results A total of 287 patients (18–65 years of age) were admitted to intensive care unit (ICU) with TBI out of which 227 patients were analyzed who had ICU stay for more than 14 days. PSH was diagnosed in 70 (30.8%) patients. Mean age of PSH positive patients was 40 ± 18 and 49 ± 11 years for PSH negative patients (p < 0.001). The age group between 40 and 50 years had a higher incidence of PSH. The age and Glasgow coma score (GCS) were significantly associated with the occurrence of PSH. The GCS score demonstrated good accuracy for predicting the occurrence of PSH with AUC 0.83, 95% CI of 0.775 to 0.886, and a p-value of 0.001. Conclusion We observed that the incidence of PSH was 30.8% in the patients with TBI. Age and GCS were found to have a significant association for predicting the occurrence of PSH. The patients who developed PSH had a longer length of hospital stay in ICU.

The present study investigates the high-temperature corrosion behavior of plasma-coated boiler steel for 1000 h in a 110-MW water tube boiler, which had encountered severe corrosion and the tube failure. The coating was carried out by alumina and MWCNTs (multiwalled carbon nanotubes)-reinforced alumina composite powders. The uncoated and coated steel substrates were hung at a platen superheater at 900 °C. After the exposure, thermogravimetric analysis was carried out to evaluate the kinetics of corrosion. XRD, SEM, TEM and EDS analysis was carried out to evaluate the corrosion products at the end of the cyclic high-temperature corrosion. The present research work concludes that CNT-reinforced alumina coatings (4.0 wt.% CNT + Al2O3 coating) have decreased the corrosion rate to 30.72 mpy, which was 113.53 mpy for conventional alumina coatings and 376.96 mpy for bare T11 boiler steel in the boiler environment. This manuscript submits the failure of tube at the platen superheater, exposure conditions and the analysis of the coated and uncoated samples of the steel tubes.

The present paper deals with the investigation of microstructure and high-temperature hot corrosion behavior of high-velocity oxy fuel (HVOF)-produced coatings. Two powder coating compositions, namely, Ni22Cr10Al1Y alloy powder and Ni22Cr10Al1Y (80wt%; microsized)-silicon carbide (SiC) (20wt%; nano (N)) powder, were deposited on a T-22 boiler tube steel. The hot corrosion behavior of bare and coated steels was tested at 900°C for 50 cycles in Na2SO4-60wt%V2O5 molten-salt environment. The kinetics of corrosion was established with weight change measurements after each cycle. The microporosity and microhardness of the as-coated samples have been reported. The X-ray diffraction, field emission-scanning electron microscopy/energy dispersive spectroscopy, and X-ray mapping characterization techniques have been utilized for structural analysis of the as-coated and hot-corroded samples. The results showed that both coatings were deposited with a porosity less than 2%. Both coated samples revealed the development of harder surfaces than the substrate. During hot corrosion testing, the bare T22 steel showed an accelerated corrosion in comparison with its coated counterparts. The HVOF-sprayed coatings were befitted effectively by maintaining their adherence during testing. The Ni22Cr10Al1Y-20wt%SiC (N) composite coating was more effective than the Ni-22Cr-10Al-1Y coating against corrosion in the high-temperature fluxing process.

Tungsten Inert Gas (TIG) welding has been learnt to be the most widely used technique among the fusion welding techniques. Welding of different components of boilers is preferably accomplished by TIG welding, due to the process capabilities of the technique to produce sound joints, even in case of Dissimilar Metal Joints (DMJ). DMJs owing to the techno-economic advantages, find vast area of application especially in boiler fabrication industry. It has been learnt that the quality of welded joints is signified by mechanical properties of the joint. The present paper is focused on the behavioural aspects of similar and dissimilar metal joints of ASME SA 213 GR. T11 and BS 3059:1987 PT 1 ERW 320, the boiler steam tube materials, prepared by TIG welding under torsional loading. It has been observed that the dissimilar metal joint has performed better than the individual similar metal joints under torsional loading by achieving 85% of the torsion strength of one of the parent metal, whereas in the case of individual similar metal joints of ASME SA213 Gr. T11 and BS3059:1987 PT1 ERW320, 78% and 68% of the torsion strength of respective parent metals has been observed. ANOVA statistics have validated the existence of significant impact of input process variables on the output quality measure of the welded joint at 95% level of confidence. The predictive models for optimum torsional strength have been proposed by regression analysis.

In the present research, the high temperature oxidation behaviour of Wire Arc sprayed Ni-5Al coating on T-11 and Gr-A1 boiler steels was studied at 9000C for 50 cycles. Each cycle consisted of 1 hour heating at 9000C followed by 20 min of cooling in air at room temperature. The kinematics of oxidation was established using weight change measurements for the bare and coated boiler steels. The oxidized samples were characterized using XRD, SEM/EDS, X-Ray mapping analyses. The coating was found to offer excellent oxidation resistance to the base steels. This may be attributed to the formation of strong protective chromium aluminium oxide phases.

In this investigation the basic in-vitro assessment of substrate (Ti-6Al-4V), as-deposited and heat treated reinforced HA coatings has been performed to evaluate the biocompatible conduct of these bio-ceramic coatings. Briefly adherent fibroblast cell lines NIN3T3 and non-adherent human peripheral blood monocyte cells (hPBMCs) were utilized to survey the surface biocompatibility utilizing standard MTT, trypan blue tests while their reactive oxygen species profiling was done to comprehend the potential pressure that may hamper the human cell working. The outcomes demonstrated that the as-deposited and heat treated coatings displayed incredible cell reasonability for hPBMCs and NIN3T3 cells in contrast with bare substrates. Comparative results were observed for trypan blue dye exclusion assay. Besides, oxygen free radical levels demonstrated that there is no change in reactive oxygen species (ROS) levels in cells cultured on heat treated coatings. This suggests the materials utilized in coatings are not cytotoxic in nature and the phenomenon was true both for cell lines just as human primary cells. By and large natural assessment showed that coatings are protected to human cells in essential conditions.

In present study, the high temperature oxidation behavior of HVOF sprayed NiCrAlY alloy coating and NiCrAlY–20SiC composite coating on T-91 boiler tube steel has been investigated at elevated temperature of 900°C for 50 cycles. The kinetics of oxidation has been established with weight change measurements. Both coatings and uncoated material obeyed the parabolic law during oxidation studies. XRD, FE-SEM along with EDS, X-ray Mapping characterization tools were utilized to check phase formation, elemental distribution and microstructure. The study resulted that both coatings performed better in oxidizing environment due to the formation of protective oxides in coated surface, however in case of uncoated steel unprotective Fe2O3 oxide was formed which led to extensive spallation. Moreover the composite NiCrAlY–20SiC coating provided more resistance to high temperature oxidation than NiCrAlY alloy coating.

Solid particle erosion studies were conducted in simulated coal-fired boiler environment in order to compare the erosion behavior of three different types of detonation gun (D-Gun)-thermally-sprayed coating powders, i.e., WC-12%Co, Cr3C2-25%NiCr and Al2O3-13%TiO2 on ASTM A36 steel and bare ASTM A36 steel. Erosion studies were conducted by using an air jet erosion test rig at impact angles of 45°, 60° and 90°. During the erosion studies, weight loss and erosion rates in terms of volume loss (mm3/g) were determined by using an optical profilometer. WC-12%Co-coated specimens exhibited the behavior closer to the behavior of ductile materials, whereas Cr3C2-25%NiCr- and Al2O3-13%TiO2-coated specimens exhibited the typical behavior of brittle materials. All the three different types of D-Gun-sprayed coating powders had successfully protected the ASTM A36 steel from solid particle erosion at an impact angle of 45°. Out of the three different types of coatings, two coatings, i.e., WC-12%Co and Cr3C2-25%NiCr, had successfully protected the ASTM A36 steel from solid particle erosion at impact angles of 60° and 90°. This paper evaluates the solid particle erosion behavior of bare and coated ASTM A36 steel which will be helpful in choosing the suitable coating for induced draft fan applications.

PurposeThis paper aims to perform the solid particle erosion studies in simulated coal-fired boiler conditions with a view to compare the erosion behavior of two different types of detonation gun (D-Gun) sprayed cermet coating powders, that is, WC-12%Co and Cr3C2-25%NiCr on ASTM A36 steel and bare (uncoated) ASTM A36 steel.Design/methodology/approachErosion studies were performed using an air jet erosion test rig at impingement angles of 45°, 60° and 90°. During the erosion studies weight loss, erosion rates in terms of volume loss (mm3/g) and measurement of erosion profiles were determined using optical profilometer.FindingsBoth cermet coatings had successfully protected the ASTM A36 steel from erosion at impingement angles of 45°, 60° and 90°. In the case of bare ASTM A36 steel, the erosion rates were maximal at an impingement angle of 45° and minimal at an impingement angle of 90°, thus depicting the peculiar erosion behavior of ductile materials. WC-12%Co coated specimens exhibited erosion behavior that is closer to the behavior of ductile materials. Cr3C2-25%NiCr coated specimens exhibited the maximum erosion rate at an impingement angle of 90° and minimum at an impingement angle of 45°, hence depicting the typical behavior of brittle materials.Practical implicationsIt is expected that these results will contribute to the improvement of erosion resistance of induced draft fans, by the application of D-Gun sprayed WC-12%Co and Cr3C2-25%NiCr cermet coatings.Originality/valueThis paper evaluates the solid particle erosion behavior of bare and cermet-coated ASTM A36 steel which will be helpful in choosing the suitable cermet coating for induced draft fan applications.

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.

Thermal spraying coating techniques have emerged as very effective surface protection technology to apply protective coatings for corrosion and wear resistance applications. These coatings have gained more importance in recent past. Advances in powder and wire production have resulted in development of various types of surface coatings with excellent wear and corrosion resistance properties. Because of excellent mechanical, thermal and electrical properties of Carbon Nanotubes, CNTs reinforced composite coatings are being developed for various applications, e.g. automotive, aerospace and sports equipment industry. It is observed that if properly deposited, these CNTs ceramic composite coatings can provide improved properties like wear and corrosion resistance. It has been found that CNTs composite coatings can be successfully deposited by thermal spraying techniques, and these coatings provide better performance than conventional coatings. This paper reviews the performance of such coatings developed by various researchers.

Hardfacing is one of the adaptable methods that can build up the hard and wear resistant surface layer of different materials on the surface of substrate material. It helps them withstand wear, as well as prevent corrosion and high temperature oxidation. In the present investigation three different types of Fe–C–Cr based hardfacing electrodes with varying chemical compositions were deposited on ASTM A36 steel substrate by using manual metal arc welding (MMAW) process. ASTM A36 steel was selected as a base material after consulting with Pressure and Process Boilers, Saharanpur (India), which is a leading manufacturer of boilers. ASTM A36 steel is mostly used by this company for the production of induced draft fans. MMAW process with direct current constant current type power source was used to deposit the hardfaced layers of uniform quality. Straight polarity was used for MMAW process so that more of the arc heat should be concentrated on the electrode. The hardfaced samples were characterized using various characterization techniques and the results of the same were also outlined in the present investigation.

Purpose This paper aims to discuss that a conventional Al2O3, 1.5 Wt.% carbon nanotubes (CNTs)-Al2O3, 2 Wt.% CNTs-Al2O3 and 4 Wt.% CNTs-Al2O3 composite coatings were deposited with the help of Plasma spray process. Design/methodology/approach To better understand the effect of CNT reinforcement on oxidation resistance, high-temperature oxidation behaviour of conventional Al2O3, 1.5 Wt.% CNTs-Al2O3, 2 Wt.% CNTs-Al2O3 and 4 Wt.% CNTs-Al2O3 composite coatings at 900°C was compared with the performance of the uncoated ASME-SA213-T11 boiler tube steel substrate. Findings The results showed that the CNT-reinforced alumina coatings exhibited better oxidation resistance and thermal stability than uncoated ASME-SA213-T11 boiler tube steel. The coated steel substrates had a lower mass gain rate than the substrate after different oxidation times. Originality/value Limited literature is available where the CNT have been reinforced into the composite alloy powders and has been thermally spray-deposited for various surface engineering applications. This research showed that with the increase in the percentage of CNTs into the alloy powder mixture, there is a significant reduction in weight gain and hence higher resistance to oxidation.

The biocompatible CaP-based coatings are deposited on the bio-materials to improve the metallurgical, mechanical and biological behaviour of medical implants in body fluid environment. Besides, these biocompatible coatings are capable to prevent the leaching of toxic ions from metal to the surrounding body environment and further their porous structure provides good osseointegration. However, in spite of these benefits, it always remains a challenge for the researchers to optimise the various properties of CaP-based coatings which finally affect their clinical performance. To achieve this, several post coating techniques have been developed. Post coating heat treatment is one of the posts coating technique which has been widely investigated by the researchers since last three decades. This review explores the impact of post coating heat treatment on the microstructural, mechanical, electro-chemical corrosion and in-vitro behavior of hydroxyapatite coatings.

Background: In most instances rapid emergence from general anesthesia after intracranial neurosurgery is desirable. The most compelling reason for this is the need for the patient to cooperate with a postoperative neurological examination intended to screen for such potential intracranial disaster as hematoma formation, herniation, and cerebrovascular accidents. Anesthetic techniques were adopted to achieve rapid emergence. In this respect, inhaled anesthetic agents have an important role in influencing the recovery time after anesthesia and surgery. The aim of this study is to compare isoflurane and sevoflurane as regard to speed of recovery from anesthesia and recovery of post-operative cognitive function in Indian populationMethods: The study was carried out as randomized control, blinded study of patients undergoing neurosurgery in tertiary care hospital. Sample sizes of 60 patients were studied. They were divided into two groups. Results: Sevoflurane shows faster emergence, extubation, motor control (in form of hand squeeze) and orientation time as compared to isoflurane. Though clinically the time difference for the various variables studied was 0.8 to 2.7 min only, statistically the results were significant and supported the basis for this difference as the difference in blood gas solubility coefficient between sevoflurane and isofluraneConclusions: Sevoflurane is recommended for use for faster extubation, emergence and post-operative neurological examination. The observation shows good brain relaxation with the use of both volatile anesthetic agents

Hot corrosion behavior of HVOF sprayed coatings, namely NiCrAlY-SiC and NiCrAlY-B4C deposited on T22 steel were studied for 50 cycles at 900 °C in an Na2SO4-60 wt%V2O5 molten-salt environment. Compound formations and microstructure were analyzed using XRD, SEM-EDS and EDS mapping techniques. Uncoated T22 steel suffered an accelerated corrosion attack due to the formation of unprotective FeO, Fe2O3, FeS and FeSO4 phases. NiCrAlY-SiC coatings showed formation of a protective layer containing SiO2, Al2O3, Cr2O3, NiO with spinals phases, whereas NiCrAlY-B4C coatings featured layers comprising B2O3, Al3BC, Al2O3, Cr2O3 and spinals phases. NiCrAlY-SiC coatings delivered greater hot corrosion resistance than NiCrAlY-B4C coatings.

The present investigation discusses the hot corrosion behavior of AlCrN and TiAlN nano-coatings on T91 boiler steel by PAPVD process subjected to molten salt of Na2SO4-60%V2O5 at 900 °C for 50 cycles. Surface and cross-sectional studies were performed by AFM, SEM/EDS and XRD techniques to understand the corrosion kinetics and mechanism. T91 bare boiler steel as well as TiAlN-coated specimen has shown higher internal oxidation as well as weight gain. The better corrosion resistance of AlCrN-coated specimen has been observed by virtue of higher availability of Cr and Al in the oxide scale as well as adherent and dense coating. The betterment of AlCrN coating can be attributed to low internal oxidation as well as movement of Cr and Al toward oxide scale to form protective corrosion barriers.

The aim of this present work was to deposit reinforced hydroxyapatite coatings with a bond coat of zirconia on Ti-6Al-4V substrate using the vacuum plasma spray technique in order to improve the surface properties. To achieve that, HA + 10 wt% Al2O3 and HA + 10 wt% ZrO2 coatings with an intermediate layer of zirconia were deposited on Ti-6Al-4V implant substrate. Further, these coatings were subjected to post-coating heat treatment at 700 °C for 1 h. The morphology and phase analysis of bio-ceramic powders, as-sprayed and heat-treated coatings, have been characterized using a scanning electron microscope and an X-ray diffractrometer. Crystallinity, surface roughness, porosity, hardness and shear strength were also investigated. The wear behaviour of the coatings was evaluated using a Taber abrasion tester as per ASTM F1978 standard. The results indicate that heat-treated coatings exhibit lower wear resistance than as-sprayed coatings and show lower porosity and higher crystallinity and hardness after heat treatment. Slight improvement in shear strength was observed after heat treatment.

In this research work, carbon nanotube (CNT)-reinforced Al2O3 coatings were prepared and successfully deposited on ASME-SA213-T11 boiler tube steel. Coatings were deposited by the plasma spray process. Ni-Cr was also used as a bond coat before applying CNTs-Al2O3 coatings. The coatings were subjected to metallography, XRD, SEM/EDAX, and X-ray mapping analysis. The porosity of CNT-Al2O3 mixed coatings was decreasing with increase in CNT content. The CNTs were found to be uniformly distributed within the Al2O3 matrix. The CNTs were chemically stable during the spray forming. It did not react to form oxides or aluminum carbides even at the very high processing temperature.

Two reinforced hydroxyapatite (HA) coatings with an intermediate layer of zirconia were deposited on Ti–6Al–4V by vacuum plasma spray (VPS) technique. In first coating, HA was reinforced with 10 wt % Al2O3 whereas in second coating, HA was reinforced with 10 wt % ZrO2. The objective of this study was to investigate the microstructure, phase formation and mechanical properties like hardness and bond strength of as-sprayed coatings and the coatings after post coating heat treatment at 700 °C for 1 h. The characterization of the coatings was performed by using SEM/EDAX, XRD, porosity, crystallinity and roughness measurement. The coatings were also evaluated for mechanical properties like hardness and tensile bond strength. It was observed that after post coating heat treatment, crystallinity increased and porosity decreased which indicated recrystallization of amorphous phases of as-sprayed coatings. Heat treatment resulted into improvement in cross-sectional hardness, however sharp decrease in bond strength was observed.

Plasma spray technique is utilized to cover the Induced Draft (ID) fans with 88%WC–12%Co (wt%) powder and 87%Al2O3–13%TiO2 (wt%) powder. The material of ID fan was ASTM A36 steel (IS2062) grade. The main focus of recent study was to investigate the influence of nature and characteristics (mainly hardness, coating thickness, bond strength, and porosity). Two coating powders with dissimilar particle size and their distribution, shape, and density were sprayed by similar parameters of plasma spraying conditions. The morphology of both the coatings was investigated by Scanning Electron Microscopy, which exhibits the sub-micro and micro-sized structure, with same thickness and porosity. Very intense and consistent was obtained and the variation in precursor size does not affect the coating structure.

Herein, a biomimetic coating of hydroxyapatite (HA)–Al2O3 and HA–ZrO2 was deposited on Ti–6Al–4V-alloy using vacuum plasma spray (VPS) technique. The bond-coat of ZrO2 has been introduced between the substrate and reinforced HA coatings to study the effect of bond-coat on structural, mechanical properties and electrochemical corrosion performance of the developed coatings. In addition, the impact of thermal treatment of coating was investigated on these properties too. Coating characteristics, such as morphology, porosity, surface roughness, and crystallinity were investigated. The corrosion performance of coatings was tested in Hank’s-based salt solution (HBSS). Significant enhancement in crystallinity and surface-hardness has been witnessed after heat treatment; nevertheless, porosity reduced. The electrochemical corrosion study revealed that the corrosion resistance of heat-treated samples was better than the as-sprayed coatings samples. The intensity of XRD peaks of all coatings increased after 24[Formula: see text]h immersion in HBSS for the electrochemical test in comparison to the intensity of peaks before the corrosion test.

In the present study, the bi-layer NiCrAlY/Al2O3-40%TiO2 coating was deposited on the three substrates (A-1, T-91, & Superfer800H) by utilizing a plasma spray technique. NiCrAlY was used as a bond coat for ensuring a proper mechanical anchorage of the topcoat (Al2O3-40%TiO2) on to it. The hot corrosion behavior of the coated as well as uncoated substrate was evaluated in an aggressive environment of Na2SO4-60%V2O5 molten salt at 900 °C for 50 cycles (1 h of heating followed by 20 min of cooling at ambient temperature). Thermogravimetric analysis was done to establish the corrosion kinetics of the coated as well as the uncoated substrate. The surface morphology of the as-sprayed and corroded products was analyzed by using a scanning electron microscope (SEM) system, and various phases formed were analyzed by utilizing an x-ray Diffraction (XRD) apparatus. Iron oxide (Fe2O3) is the principal phase formed in the tested uncoated substrate which is non-protective in nature; whereas the presence of Al, and Ti oxides along with some minor oxides of Ni, and Cr were observed in the oxide scale of the tested coated substrate, which are protective and remain stable even at harsh environment condition. The weight gain shown by the coated substrate is less as compared to the uncoated substrate, which indicates the usefulness of the coating.

The failure analysis of the damaged surfaces is crucial for the selection of most expedient process and processing parameters leading to longer mean time between failures. Many procedures are being developed and deployed to determine the kind and severity of failure and to prevent the hot forging die failure. In spite of all these efforts, the losses still occurred in terms of profitability. However, there is no comprehensive review of failures of hot forging dies, to examine and understand their current research status to solve the failure problem, has been done. Here, an updated review of various kinds of failures and their causes has been presented in general. The goal of this paper is to communicate an updated perspective of kind of failures such as wear (Abrasive and Adhesive), plastic deformation, fatigue (thermal and mechanical) occurs due to high thermal combats, mechanical strain, whorled loading and corrosion while hot forging process. The paper will help the better understanding of directions in which research of failure analysis has been done relevant to the hot forging industries and will assist in the prevention/prolongs of die failure.

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.

WC-12%Co, Cr3C2-25%NiCr, 80%Ni-20%Cr, 87%Al2O3-13%TiO2 coatings were deposited by Air Plasma Spray (APS) technique on ASTM A36 steel. Erosion behaviour of sprayed coated samples were investigated at three different impact angles (45°, 60° and 90°). The mechanism of erosion was investigated on uncoated and coated samples. The rate of erosion of the substrate first increased with increasing angle of impact and then gradually decreased. But the erosion rate of the coated samples increased steadily. Substrate shows the higher metal removal whereas coating shows the higher erosion resistance. WC-12%Co coated samples performed well in erosion testing and offered best erosion resistance as compared to the substrate and all other coatings. Ductile fracture takes place on substrate material at higher impact angle. Overall, all the coated samples have shown less erosion propensity when compare to the bare one.

Coatings of alumina and titania of two different compositions and at different angles has been developed using plasma spraying method. The surface and cross-sectional morphological characterizations of Al2O3 and Al2O3/ TiO2 powders and coatings were done by scanning electron microscope (SEM). The microwave absorbing properties of developed coatings has been observed in X-band (8.2-12.4GHz) frequency range using network analyzer. The reflection loss of Al2O3 is -19dB at 10.495GHz with a bandwidth of 0.32Hz whereas reflection loss of Al2O3/ TiO2 87:13 is -23dB at 10.265GHz with a bandwidth of 0.8GHz. The coatings absorbed 90% of the incident electromagnetic radiation which indicates the material’s radar absorbing potential. With appropriate composition and proper spray angle the microwave absorbing properties has been improved.

Crop yield forecasting is the methodology of predicting crop yields prior to harvest. The availability of accurate yield prediction frameworks have enormous implications from multiple standpoints, including impact on the crop commodity futures markets, formulation of agricultural policy, as well as crop insurance rating. The focus of this work is to construct a corn yield predictor at the county scale. Corn yield (forecasting) depends on a complex, interconnected set of variables that include economic, agricultural, management and meteorological factors. Conventional forecasting is either knowledge-based computer programs (that simulate plant-weather-soil-management interactions) coupled with targeted surveys or statistical model based. The former is limited by the need for painstaking calibration, while the latter is limited to univariate analysis or similar simplifying assumptions that fail to capture the complex interdependencies affecting yield. In this paper, we propose a data-driven approach that is "gray box" i.e. that seamlessly utilizes expert knowledge in constructing a statistical network model for corn yield forecasting. Our multivariate gray box model is developed on Bayesian network analysis to build a Directed Acyclic Graph (DAG) between predictors and yield. Starting from a complete graph connecting various carefully chosen variables and yield, expert knowledge is used to prune or strengthen edges connecting variables. Subsequently the structure (connectivity and edge weights) of the DAG that maximizes the likelihood of observing the training data is identified via optimization. We curated an extensive set of historical data (1948-2012) for each of the 99 counties in Iowa as data to train the model.

In the present study, reinforced hydroxyapatite (HA) coatings (HA + 10 wt% Al2O3 and HA + 10 wt% ZrO2) were deposited on SS-316 L substrate with an intermediate layer (bond coat) of zirconia by vacuum plasma spray technique. The so-formed reinforced HA coatings were heat treated at 700 °C for 1 h. The influence of post coating heat treatment on phase composition, microstructure, mechanical and electrochemical corrosion properties were investigated. As-sprayed and heat treated coatings were characterized by x-ray diffraction, scanning electron microscope, surface roughness, porosity and crystallinity. Results showed that after post coating heat treatment, the structural integrity of HA has been completely re-established. Moreover, significant drop in porosity has been observed due to the sintering effect produced by heat treatment. Considerable improvement in nanohardness and shear strength was witnessed; however, the nanohardness of top layer was decreased after annealing due to the weak bonding of partially melted and un-melted particles with fully melted splats caused by diffusion process. As-sprayed coatings exhibited higher wear resistance compared to heat treated coatings. Nevertheless, post coating heat treatment effectively enhanced the corrosion resistance of coatings, since, the heat treatment lead to densification of coatings microstructure which further reduces the active sites for dissolution.

Thermal spray coatings can be applied economically on machine parts to enhance their requisite surface properties like wear, corrosion, erosion resistance, and so forth. Detonation gun (D-Gun) thermal spray coatings can be applied on the surface of carbon steels to improve their wear resistance. In the present study, alloy powder cermet coatings WC-12% Co and Cr3C2-25% NiCr have been deposited on ASTM A36 steel with D-Gun thermal spray technique. Sliding wear behavior of uncoated ASTM A36 steel and D-Gun sprayed WC-12% Co and Cr3C2-25% NiCr coatings on base material is observed on a Pin-On-Disc Wear Tester. Sliding wear performance of WC-12% Co coating is found to be better than the Cr3C2-25% NiCr coating. Wear performance of both these cermet coatings is found to be better than uncoated ASTM A36 steel. Thermally sprayed WC-12% Co and Cr3C2-25% NiCr cermet coatings using D-Gun thermal spray technique is found to be very useful in improving the sliding wear resistance of ASTM A36 steel.

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.

Agricultural waste is produced at agricultural premises as a result of an agricultural activity. Agriculture residue is made up of organic compounds from the living plants like rice straw, oil palm empty fruit bunch, sugarcane bagasse, coconut shell, banana leaves and others. This research has highlighted their eco-friendly nature and high microwave absorption properties, developing a new and improved form of pyramidal absorbers including high carbon content coal in it. Software simulation is done using CST Microwave studio. Samples are developed using a new technique by adding cobalt as an accelerator, and its performance is analyzed in terms of its reflection loss performance using free space measurement method in the frequency range of 8.2 to 12.4 GHz. This research gives a different definition to microwave absorbers as it is based on environmental and eco- friendly materials unlike commercial absorbers which use polyurethane and polystyrene plastic based materials that pose harm to the surroundings as well as human beings by releasing toxic gases when operating under high temperatures (1). Basic material used is dried banana leaves which comes under the category of agricultural wastes and have a great potential of being used as a good microwave absorber. They are the most essential elements of an anechoic chamber to reduce signal interference. In order to increase the absorption properties of the basic material, finely powdered coal is added due to its high porosity and carbon content. A comparison is shown between banana leaves and banana plus coal as microwave absorbers enhancing the absorption capacity of basic material. The results for these unique types of absorbers are even better than the commercial absorbers. Abandoned agricultural wastes pose a risk to the environmental and public health. While effectively absorbing microwave signals, polyurethane material particulates over time adding contaminants to clean rooms and reducing absorber lifetime. An alternative to these absorbers is found using agricultural wastes like banana leaves, sugarcane bagasse, rice husk etc. for the same purpose. These absorbers are composed of renewable materials and eliminate the toxic gas release problem for polyurethane materials under high power test conditions. They are cost effective materials and can be used to make environment friendly microwave absorbers with desired results. India is the largest producer of the bananas in the world contributing to 28% of world's banana production. Around 20-30% of the by products including banana leaves get wasted every year (9). This waste can be effectively utilized in development of microwave absorbing materials due to presence of high amounts of carbon content (43.5%) in it (2). Macro pores in carbon help in absorption. Table 1 shows weight percentages of different elements in banana leaves.

Rice husk and coal is an innovation in enhancing the microwave absorption properties of pyramidal microwave absorbers to be used in radio frequency anechoic chambers. An anechoic chamber consists of radar absorbing material (RAM) along its wall; floor and ceiling to eliminate unwanted reflections to create electromagnetically quite environment. To design the pyramidal microwave absorber, coal has been added to rice husk. This innovative material combination has been investigated to determine the best reflectivity performance of pyramidal microwave absorbers. In the commercial market, polyurethane and polystyrene are the most popular foam based material that has been used in pyramidal microwave absorber fabrication. Simulation tool that has been used is CST Microwave Studio. Simulation based comparison of rice husk and combination of rice husk plus coal is done in the frequency range of 0-20 GHz. Chemicals used to intact the powdered form of rice husk and coal are polyester resin, methyl ethyl ketone peroxide (MEKP) and cobalt. Pyramidal microwave absorber has been tested using dielectric probe method and radar cross section method (RCS). Reflection loss performance is tested in the frequency range of 8.2 to 12.4 GHz.

Hydroxyapatite powder reinforced individually with 10 wt percentage (wt%) of Al2O3 and ZrO2 (HA + 10 wt% Al2O3 and HA + 10 wt% ZrO2) was thermally sprayed onto SS-316L substrate with a bond coat of Zirconia by vacuum plasma spray (VPS) technique. The resulted coatings were heat treated at 700 °C for 1 h to study its effects on microstructural and mechanical properties of the deposited coatings. The characterization of the coatings was carried out using scanning electron microscope, x-ray diffraction, porosity, surface roughness and crystallinity using Rietveld analysis. The results indicated that after post coating heat treatment substantial decrease in porosity was witnessed along with significant improvement in crystallinity. Besides, the hardness across the cross-section of the coatings and bond strength was considerably improved; however the hardness of top coat was reduced owing to the loosening of un-melted and partially melted particles by diffusion process which takes place during heat treatment.