Superalloy Materials Research Articles

Determination and verification of parameters in the dynamic constitutive for Inconel 718 superalloy

Abstract Inconel 718, which is a nickel-based superalloy material used in aero engines, may be subjected to intense dynamic loading in an accidental engine failure. However, the material models for Inconel 718 employed in existing studies can not describe the mechanical behaviors under complex stress states, high strain rates and elevated temperatures satisfactorily. In this paper, various parameters of a previously proposed dynamic constitutive model for Inconel 718 are determined and verified. First, the parameters of strength, strain rate effect, temperature effect and failure for precipitation hardened Inconel 718 are calibrated against various material tests. Then, the parameters are verified by comparing the numerical results obtained from the dynamic constitutive model with the corresponding ballistic test data. It transpires that the numerical results agree well with the test data, which demonstrates the accuracy and effectiveness of the dynamic constitutive model for Inconel 718. It can also be concluded that the consideration of Lode angle effect and precise descriptions of strain rate and temperature effects are significant for the reproduction of mechanical responses of Inconel 718 plates under intense dynamic loadings in numerical simulations.

Microstructural evolution and high temperature hot corrosion behaviour of AlCoCrFeNiTi high-entropy alloy coatings

The fuels used contain undesirable impurities such as Na, V, K, S, and Mg in gas turbine engines. These impurities react with hot components under service conditions, leading to the deterioration of the thermal barrier coatings (TBCs) structure and the formation of hot corrosion damage. In this study, metallic powders containing CoNiCrAlY were deposited as bond coat on Inconel 718 superalloy material using high velocity oxygen fuel (HVOF) coating technique. High entropy alloy (HEA) powder containing AlCoCrFeNiTi was synthesized as coating material using mechanical alloying (MA) method. AlCoCrFeNiTi powders were produced using atmospheric plasma spray (APS) coating technique. The produced coating system was subjected to hot corrosion tests at 700 °C and 800 °C temperatures for different time periods in corrosive environment conditions containing Na2SO4 (sodium sulfate) and V2O5 (vanadium pentoxide). Hot corrosion behavior of the coating system was determined, damage formations and degradation processes were investigated in detail. As a result of the determination and synthesis of HEA powder materials, production of coatings, experimental studies and hot corrosion test studies under service conditions, it was seen that the Ti-containing AlCoCrFeNi HEA coating system has usable qualities without any damage such as cracking, buckling or spalling.

Superalloys fracture process inference based on overlap analysis of 3D models

Superalloy materials exhibit susceptibility to fracture failures stemming from the influence of thermomechanical factors. To comprehensively understand the fracture mechanisms, material properties, root causes of failure, and the subsequent optimization of alloys, a detailed analysis of the internal fracture process and the morphological traits of the fracture surface is imperative. Traditional analysis of fracture surfaces solely relies on 2D images, thus lacking crucial 3D information. Although in situ experiments can capture the fracture process, their effectiveness is confined to the specimen’s surface, precluding insight into internal changes. Here we introduce an integrated framework encompassing the process of 3D reconstruction of fracture surfaces, aiming to enhance the visual information obtained with micron-level accuracy, visual intuitiveness and sense of depth. Additionally, this framework also facilitates the scrutiny and inference of internal fracture processes. These results demonstrate that under specific service conditions, material deformation fracture probably stems from a combination of surface cracking and internal cracking rather than exclusively one or the other. Overall, our description and analysis of internally initiated cracking due to defects within the specimens can be beneficial in guiding future alloy design and optimization efforts.

Theoretical prediction of high temperature mechanical, thermodynamic and surface O adsorption properties of W-Cu alloys: Advanced high temperature super strength alloy materials

This paper constructs four alloy structural models of W15Cu1, W14Cu2, W13Cu3 and W12Cu4 as research objects. Based on phonon spectra analysis, the structure of W12Cu4 is unstable. Thus, the mechanical and thermodynamic properties for pure W, W15Cu1, W14Cu2 and W13Cu3 are studied using first-principles methods. The results show that the bulk modulus of W-Cu alloys exhibits the characteristics of high-temperature strength alloys. In particular, the bulk modulus of W14Cu2 and W13Cu3 increases rapidly with temperature increasing; Meanwhile, The W-Cu alloys at high temperatures exhibit low expansion behavior. The coefficient of thermal expansion of W14Cu2 at 1290 K starts to be lower than that ofW, and decreases with temperature increasing. At 1370 K, the coefficient of thermal expansion of W13Cu3 begins to be lower than that of W14Cu2, which also decreases with temperature increasing. The W-Cu alloys at high temperatures exhibit excellent phonon thermal conductivity. The phonon thermal conductivity of W14Cu2 at 2230 K transcends pure W and then maintains a thermal conductivity of about 5.55Wm-1K−1. The phonon thermal conductivity of W13Cu3 at 2140 K begins to transcend W14Cu2, and also exceeds pure W at 2180 K, and increases rapidly with temperature increasing. At 0 K, the addition of Cu to W reduces the mechanical strength but increases the ductility.

Understanding tool cutting-edge microstructure and deformation mechanism induced by adhesive wear in the turning of nickel-based superalloys

Nickel-based superalloy has great potential in the aerospace industry as key components. However, difficult-to-machine characteristics have further limited its application. Thermal-barrier coatings of the titanium-based family on carbide tools offer exceptional performance in cutting superalloys, combining high-temperature stability and remarkable toughness. This work primarily concentrates on understanding cutting-edge microstructure and deformation induced by tool adhesive wear in the turning of nickel-based superalloys with experiment and modelling. The dominant tool wear mechanisms are revealed to be adhesive wear and abrasive wear by SEM/EDS. The microstructure of the cutting-edge interface is qualitatively and quantitatively investigated by SEM/EDS and EBSD. The adhesive layer thickness at cutting edge is about 10–30 μm. The GND density of WC grains at cutting edge is 15-20 × 1014/m. The nanomechanics properties of the tool wear interface were quantitatively evaluated by nanoindentation. The average hardness of WC and Ni-superalloy at cutting-edge interface is evaluated to be 15–19 GPa and 6.2–6.5 GPa, respectively. Further, the underlying deformation mechanisms induced by tool wear behaviours are revealed through the transient heat conduction model and cutting-edge stress distribution model. This research offers a framework and mechanism for the cutting tool wear surface/interface characteristics targeted to the difficult-to-cut superalloy materials.

Joining Behaviour of Thick Plate Using High-Frequency Induction Assisted Arc Welding

Combining a preheating source with conventional arc welding is a promising method to study the weld quality and improvement of strength for high-strength super-alloy materials. The present research used an induction preheating source with plasma arc welding (PAW) to weld Inconel 625 thick plates. The investigation was performed at a constant induction current of 600 A, welding speed of 100 mm/min and a plasma welding current of 135 A. The induction-assisted plasma arc welding (IAPAW) demonstrated that a weld joint was possible with static induction preheating and a high plasma welding current at low welding speed. The microstructural observation showed various dendritic structures in the fusion zone (FZ). The FESEM and EDX analysis confirmed the formation of Laves phase in the interdendritic structure of the FZ. The ultimate tensile strength of the IAPAW joint reached to 658 MPa. The tensile fracture surface of the welded sample revealed a lower number of dimples, indicating the reduction of ductility. The XRD analysis was carried out at various zones and it confirmed the peak shifting towards the higher 2-theta value of the FZ.

Development of thermal barrier coating on single crystal superalloy CMSX-4 by two-source evaporation EB-PVD and hot corrosion performance of the coating in a simulated aero-engine environment

Superalloys are crucial in high-temperature applications, particularly in the gas turbine industries. With the development of high-temperature superalloy materials, efforts are still being made to improve the turbine entry temperature (TET), which will ultimately raise the efficiency of gas turbines. In this research, a second-generation single-crystal superalloy CMSX-4 based on nickel was prepared. The surface was coated by thermal barrier coating (TBC) with a bond coat of NiCoCrAlY with vacuum plasma spray (VPS) and a top coat with Yttria Stabilized Zirconia (YSZ) by Electron Beam Physical Vapor Deposition (EB-PVD) with a minimal current of 2.3 A with two sources compared to the conventional high-current that has been currently employed. These CMSX-4 specimens, both the as-cast and TBC coated, were used to test the effects of cyclic oxidation and hot corrosion at 1000 °C, simulating an aircraft engine. Also, a hot corrosion test using salt compositions (Wt%) of 60Na2SO4 - 40NaCl was performed simulating an aviation engine environmental condition. A FE-SEM/EDS analysis was used to examine the surface and cross-section microstructures of oxidized, hot-corroded as-cast, and hot-corroded TBC-coated CMSX-4 and its corrosion products. Using the XRD technique, the phases that were found in the oxidized and hot-corroded samples were identified. The outcome demonstrated that the EB-PVD TBC-coating on CMSX-4 with beam switching technique and a lower electron beam current has adequate protection without any damage to the coatings at 1000 °C.

PmcaNet: Pyramid multiscale channel attention network for electron microscopy image segmentation

Recent advances in high-throughput electron microscopy (EM) have revolutionized the examination of microstructures by enabling fast EM image generation. However, accurately segmenting EM images remains challenging due to inherent characteristics, including low contrast and subtle grayscale variations. Moreover, as manually annotated EM images are limited, it is usually impractical to utilize deep learning techniques for EM image segmentation. To address these challenges, the pyramid multiscale channel attention network (PmcaNet) is specifically designed. PmcaNet employs a convolutional neural network-based architecture and a multiscale feature pyramid to effectively capture global context information, enhancing its ability to comprehend the intricate structures within EM images. To enable the rapid extraction of channel-wise dependencies, a novel attention module is introduced to enhance the representation of intricate nonlinear features within the images. The performance of PmcaNet is evaluated on two general EM image segmentation datasets as well as a homemade dataset of superalloy materials, regarding pixel-wise accuracy and mean intersection over union (mIoU) as evaluation metrics. Extensive experiments demonstrate that PmcaNet outperforms other models on the ISBI 2012 dataset, achieving 87.85% pixel-wise accuracy and 73.11% mean intersection over union (mIoU), while also advancing results on the Kathuri and SEM-material datasets.

Investigation and optimization of multiple objectives by hybrid evolutionary algorithms for turning of Nimonic 80A under nano MQL environment

ABSTRACT Nimonic80A is one of the hard-to-cut superalloy materials. However, machining the same remains difficult. The present study’s objective is attained by taking surface quality and tool wear as output core attributes of machining by deploying conventional statistical approaches and meta-heuristic optimisation algorithms to find optimal input attributes. Optimal input parameters were found using ANN hybridised with meta-heuristic optimisation algorithms, considering cutting acceleration as one of the response attributes along with cutting force (Fz), flank wear (Vb) and surface roughness (Ra). In this process, nanofluids were formulated by suspensions of graphene oxide into rice bran oil as the minimum quantity lubrication (MQL). Experiments were conducted based on L27 Taguchi experimental trials, and the experimental results revealed that minimum feed rate and cutting velocity reduced the cutting force, surface roughness, and tool flank wear up to 51% during nano-MQL turning conditions compared to dry machining. Thus, an artificial neural network (ANN) was used to generate the model for each machining response, which was further interfaced with multiobjective particle swarm optimisation (MOPSO) and multiobjective mayfly algorithms (MOMA) as a hybrid algorithm for finding optimal parameters. The optimal results were compared, and ANN-MOMA was found to be better.

On the surface integrity of machined aero-engine grade Ni-based superalloy billets produced by the field-assisted sintering technology (FAST) route

High performance powder-based Ni-based superalloys exhibit exceptional in-service properties at elevated temperature, however this leads to reduced machinability and the potential for significant machining induced damage. Field assisted sintering technology (FAST) is capable of consolidating powder rapidly and efficiently, allowing for precise control of the microstructure via the dissolution of strengthening phases. In this study, subsolvus and supersolvus dwell temperatures were utilised to produce fine and coarse grain forms of an advanced Ni-based disk alloy. Surface integrity and machining forces were then evaluated after single point turning for a range of surface speeds. Higher cutting forces and lower depths of subsurface damage were generated when machining the fine grain (subsolvus) material when compared to the coarser grained (supersolvus) material. For both material conditions tested, higher surface speeds led to a reduced depth of subsurface deformation due to increased local temperatures, promoting workpiece softening. In addition, at higher cutting speeds the deformation of near surface γ’ precipitates were observed to be greater. These results demonstrate that the FAST process can be utilised to control microstructure, and as a result, tailor the machinability of Ni-based superalloy material.

Fabrication of PCD face grinding wheel with positive rake angle by femtosecond laser and its performance evaluation in cemented carbide grinding

Super-hard abrasive grinding is considered to be the main approach to realize precision and ultra-precision machining of difficult-to-machine materials such as cemented carbide, engineering ceramics, titanium alloys and superalloy materials encountered. However, heavy grinding force, high grinding temperature and poor surface integrity are prone to be encountered in conventional negative rake angle grinding of difficult-to-machine materials. In response to these problems, a novel concept of positive rake angle grinding is first proposed and an abrasive grain regularly arranged binder-less polycrystalline diamond face grinding wheel with positive rake angle has been designed and fabricated by femtosecond laser ablation. To evaluate the grinding performance of the face grinding wheel with positive rake angle, grinding experiments of YG8 cemented carbide are conducted and compared with the traditional electroplated diamond grinding tool with equivalent abrasive grain dimension and distribution. The results show that compared with the conventional negative rake angle grinding, the normal and tangential forces in positive rake angle face grinding are reduced by 30.3 % ∼ 36.4 % and 21.1 % ∼ 29.3 %, respectively, and the ratio of normal to tangential force is reduced by 12.6 % ∼ 20.3 %. The surface roughness and average depth of subsurface metamorphic layer are also significantly smaller. The laser fabricated polycrystalline diamond face grinding wheel also has better wear resistance in the grinding of cemented carbide. Therefore, it can be concluded that better ground surface quality is obtained by the novel grinding wheel with positive rake angle. The innovative grinding method can fill the research gap on the grinding mechanism of positive rake angle grinding and further enrich the grinding theory of difficult-to-machine materials.

Experimental investigations on wire arc additive manufacturing process using an Inconel 625 alloy wire

The current research investigates the use of an automated cladding welding machine for wire arc additive manufacturing (WAAM) of a semi-cylindrical part using a 1.2 mm nickel- chromium-molybdenum alloy wire (ERNiCrMo-3). The gas tungsten arc welding process was adopted to create a 32 mm thick and 60 mm long part. Onwards, standard tests were performed to evaluate the part’s hardness, yield, and tensile strengths at various sections along the part’s length and thickness. One of the objectives was also to identify any potential change in the mechanical properties of the Nickel wire when employed in WAAM process. Moreover, microstructure along the depth was examined using SEM to ascertain bonding between deposited layers and identify any porosities. The material’s hardness was found relatively higher than the original wire; somewhere about 27 HRC in the horizontal plane and 26.8 to 28.5 HRC in the vertical plane. Additionally, the study shows that the direction across the thickness (X) had the lowest values for both tensile and yield strength. While, examination at the microscopic level revealed that in both orientations: parallel (X) and perpendicular (Y) to the direction in which the layers were deposited, exhibited a high level of ductility. This confirms the possibility of an additive manufacturing procedure adopted for this super-alloy material without significantly changing its mechanical properties. While, there is room for improvement in properties by optimizing the machine parameters.

Conjugate heat transfer analysis of internally cooled superalloy turbine blades with grooved channels

The present work reports a conjugate heat transfer analysis of a turbine blade exposed to high-temperature compressible gas flow and the convection cooling inside the blade. A nickel-based superalloy material CMSX-4 with better mechanical and anticorrosive properties has been introduced for blade materials, and grooved channels are proposed for heat transfer enhancement in internal convection. Each channel contains nine mini-grooves having groove-depth to channel-diameter ratio in the range of 0.08–1.12. Three prominent turbulence models, namely, k-ε, k-ω shear stress transport (SST), and γ-θ transition SST, are used to capture the flow turbulence in a transonic boundary layer flow. Simulations have been performed for actual operating conditions of turbine blades with a wall-to-gas temperature ratio of 0.84 and an inlet-to-outlet pressure ratio of 1.69. The inlet Reynolds number is 5.3 × 105 for the hot gas region, and for coolant flow, the Reynolds number varies from 16 000 to 70 000. The Mach number reaches to a maximum value of 1.14 in the external hot gas flow. Boundary layer transition and wake flow from nearby blades affect the flow in the suction side of the blade. The incorporation of scalable wall function improves the performance of the k-ε turbulence model. Compared to the smooth channel, a 25 K reduction in the average blade surface temperature and 27.3% enhancement in the Nusselt number in blade cooling are obtained for the grooved cooling channel.

Geometric Structures for Sialon Ceramic Solid End Mills and Its Performance in High-Speed Milling of Nickel-Based Superalloys

Sialon ceramic tool material has become one of the most ideal materials for the high-speed cutting of superalloy materials. However, studies on the geometric structure of sialon ceramic solid end mill is lacking at the present. In this work, the geometric structure of sialon ceramic end mills was designed for difficult-to-machine nickel-based superalloy materials. The cutting force and heat, flank wear and machined surface quality were analyzed to study the effect of the main parameters on tool performance. The results showed that the end mill experienced severe flank wear and chipping, which were the leading cause of its failure during high-speed cutting. The cutting force and temperature decreased gradually with the increase in the helix angle. With the increase in the rake angle, the flank wear and the quality of the machined surface of the specimen first decreased and then increased. With the increase in the relief angle, the cutting temperature of the ceramic end mill gradually decreased, and the cutting force and the machined surface roughness showed an initial decrease and then increased. When the helix angle, rake angle and relief angle were 35°, −15° and 12°, respectively, the sialon ceramic end mill exhibited the best cutting performance and obtained better machined surface quality in the nickel-based superalloys.

Molten pool flow behavior and influencing factors in electron beam selective melting of IN738 superalloy

Electron beam selective melting (EBSM) has emerged as a promising technology for additive manufacturing (AM) of superalloys. In this study, a comprehensive multi-physics model is developed to analyze the molten pool flow behavior and influencing factors in the EBSM process. The discrete element method (DEM) and volume of fluid (VOF) method are employed to establish the powder bed model and track the solid-liquid free surface, respectively. The results reveal that the molten pool exhibits a conduction mode characterized by a large width-to-depth ratio driven by the Marangoni effect. Internal vortices cause the molten pool to expand even after the scan ends. The ambient pressure, in comparison to the preheat temperature, has a significant impact on vapor recoil and consequently affects the surface quality of the molten pool. Moreover, a large hatch distance results in cracks and porous morphological features on the surface of the samples. These findings demonstrate the effectiveness of numerical simulations in providing detailed insights into the EBSM process of the IN738 superalloy material.

Investigating thermal shock and corrosion resistance of Inconel 601 super alloy after thermal barrier coating with %8 YSZ powder

Superalloys, which are categorized in three groups as iron-based, nickel-based and cobalt-based, are used especially in high temperature applications. Inconel 601 alloy, a nickel-based superalloy, is widely used in applications such as chemical processing, aerospace, power generation, heat treatment, chemical refining and gas turbine engines. Although the mechanical properties of superalloy materials and their resistance to wear, corrosion and oxidation are better than other metallurgical materials, these properties are not satisfactory in some applications. In such cases, the desired properties can be obtained by applying heat treatment and coating processes to superalloys. In this study, approximately 100, 200 and 300 µm ceramic top coat thickness thermal barrier coating system with NiCrAlY and 8%YSZ powder coating materials, were created for the Inconel 601 substrate material and SEM, EDS and XRD datas are given. Then, electrochemical corrosion test with 3.5% NaCl solution and 8 cycles of thermal shock test at 1200 °C using FCT thermal shock method were applied to the samples. Considering the corrosion rate values and SEM images after the electrochemical corrosion test, it was determined that the sample with the highest corrosion resistance was the sample with a ceramic top coating thickness of 100 µm. The reason for this is that as the coating thickness increases in thermal barrier coatings, the tension increases and accordingly, a change in pore and crack density occurs. The fact that the samples with a ceramic top coating of 100 µm thickness have the highest corrosion resistance can be explained in this way. Considering that the pore and crack ratio decreases due to the sintering effect in the SEM images of the samples after the thermal shock test, but considering that the TGO layer thickness will increase at higher temperatures and longer service conditions, in regards to thermal barrier coating deformation, it was concluded that the samples with 100 and 200 µm ceramic top coating thicknesses were safer in terms of thermal shock.

Study on milling tool wear morphology and mechanism during machining superalloy GH4169 with PVD-TiAlN coated carbide tool

Tool life, dimension accuracy and surface quality of workpiece, intelligent operation and maintenance of automated production are closely related to tool wear. However, for many years, relevant scholars have mainly focused on the research of the tool wear mechanism in the sharp wear stage, mainly involving various machining methods, various superalloy materials, various tool materials and geometric parameters, and different coolant methods et, al. The morphology and mechanism of tool wear need to be further studied in the initial and steady wear stage, which is helpful to ensure the dimensional accuracy and surface quality of workpiece, especially in the finishing stage. 45 groups of tool wear experiments are carried out under dry condition during milling of GH4169 with PVD-TiAlN coated carbide tools. The tool wear micro-topography, tool wear curve, tool cutting force, spindle motor current, tool wear mechanism, chip topography and machined surface topography were investigated during the milling tool wear. The tool wear mechanism in the sharp wear stage was further explored by SEM, EDS and XRD, which will help to deeply gain the milling characteristics of GH4169 and help to test the cutting performance of the tool. The results show that during the tool wear process of milling superalloy GH4169, severe abrasive wear and adhesive wear occur in large numbers, the rate of tool wear is fast, the cutting force increases, the current of the spindle motor increases, and the tool coating and substrate material were worn seriously, the main tool wear mechanisms are abrasive wear, adhesive wear, oxidative wear and breakage. Severe abrasive wear occurs between lots of hard abrasive carbides in the workpiece material and the rake and flank faces of the milling tool. Fe, Cr, Al, etc. were found on the rake and flank faces, and the adhesive wear was very serious. Many oxides (Al2O3, Fe2O3, etc.) appear on the rake and flank surfaces, which indicate that oxidative wear occurs. Due to the periodic intermittent cutting during the milling process, the breakage of milling tool edge is very serious. Chips or adherents with different microscopic topographies were adhered to the tool wear area due to extrusion and stretching in the sharp wear stage. The machined surface micro-topography of the workpiece, which affected by tool wear, was greatly of difference during the entire wear stage.

A spatiotemporal two-level method for high-fidelity thermal analysis of laser powder bed fusion

Numerical simulation of the laser powder bed fusion (LPBF) procedure for additive manufacturing (AM) is difficult due to the presence of multiple scales in both time and space, ranging from the part scale (order of centimeters/seconds) to the powder scale (order of microns/milliseconds). This difficulty is compounded by the fact that the regions of small-scale behavior are not fixed, but change in time as the geometry is produced. While much work in recent years has been focused on resolving the problem of multiple scales in space, there has been less work done on multiscale approaches for the temporal discretization of LPBF problems. In the present contribution, we extend on a previously introduced two-level method in space by combining it with a multiscale time integration method. The unique transfer of information through the transmission conditions allows for interaction between the space and time scales while reducing computational costs. At the same time, all of the advantages of the two-level method in space (namely its geometrical flexibility and the ease in which one may deploy structured, uniform meshes) remain intact. Adopting the proposed multiscale time integration scheme, we observe a computational speed-up by a factor × 2 . 44 compared to the same two-level approach with uniform time integration, when simulating a laser source traveling on a bare plate of nickel-based superalloy material following an alternating scan path of fifty laser tracks. • A Two-level method is extended to a spatiotemporal formulation without continuous mesh update. • The two-level formulation allows for full scale separation, such that different spatial and temporal approximations are used on each scale. • An overall speed-up factor of approximately 2.5 is observed while the temperature profile closely captures reference solutions.

SURFACE TOPOGRAPHY AND OPTIMAL MACHINING CHARACTERISTICS INVESTIGATION FOR ADVANCED ENGINEERING MATERIAL INCONEL 825 ALLOY EXPLORING STATISTICAL TGRA ACCOMPANIED WITH T-TOPSIS METHODOLOGY

The electrical discharge machining (EDM) is an extremely effective manufacturing process to create deep and three-dimensional complex cavities. In EDM, machining occurs due to the generation of thermoelectric energy between the work piece and an electrode. EDM widely engaged for cutting superalloy material that are having high strength to wear ratio, corrosion resistance, etc. In this work, Inconel 825 material, which is nickel–chromium based superalloy, is opted due to its outstanding mechanical and thermal properties. We considered various important EDM input parameters, i.e. spark gap (Sg), gap voltage (Vg), pulse on time ([Formula: see text]), pulse off time ([Formula: see text]), peak current ([Formula: see text]), servo feed (Sf), depth of cut (Dc) and difficulty index (Di) with Taguchi L[Formula: see text] orthogonal array for optimizing output responses, i.e. tool wear rate (TWR), material removal rate (MRR) and surface crack density (SCD) in multi-objective optimization (MOO) realm. Undertaking repeated experimental runs are very expensive, tedious, time consuming and economically unjustified. Hence, we have robustly introduced a novel integrated computational Taguchi based grey relational analysis (TGRA) accompanied with Taguchi based technique for order of preference by similarity to ideal solution (T-TOPSIS) to optimize the EDM process. This research represents that the pulse on time is the chief significant factor and the [Formula: see text] value is found as 0.002 for both TGRA and T-TOPSIS. Experimentally, it has been confirmed that the optimum settings yielding an improvement of 0.01627 and 0.28071 in TGRA and T-TOPSIS score, respectively. The comparative analysis for the methodologies is fruitfully discussed and the results clearly present the effective parametric combinations to be implicated for optimizing MOO framework. Investigation of surface topography is fruitfully presented and the effects of the pulse on time, gap voltage and pulse off time on heat affected layers, machining debris and surface cracks were also discussed. Validation tests were carried out and show closer relationship with the experimental results.

A Comprehensive Study of Ceramic Matrix Composites for Space Applications

Ceramic matrix composites (CMCs) have grown in popularity as a material for a range of high as well as protection components, increasing the need to better understand the impacts of multiple machining methods. It is primarily composed of ceramic fibers embedded in the matrix. Ceramic materials, especially carbon fibers and carbon were used to create the matrix and fibers. These ceramics include a huge variety of non-metallic inorganic materials that are regularly utilized under high temperatures. The aircraft industry became revolutionized by this unique combination of materials, which made parts better resistant under extreme conditions as well as lighter than the earlier technology. The development, properties, and production of ceramic matrix composites, as well as space applications, are discussed in this article. Ceramic materials have an interesting set of properties, including great strength and stiffness under extremely high temperatures, chemical inertness, low density, etc. In CMC, ceramics are used in the matrix as well as reinforcement. The matrix material keeps things running smoothly while the reinforcement delivers unique special properties. Ceramic matrix composites are developed for applications that required high thermal and mechanical characteristics, which include nuclear power plants, aircraft, chemical plants, space structures, and transportation services. Even though advanced aircraft relies on high-performance propulsion systems, improving the total impulses over the total mass ratio for rocket engines becomes essential for improving their performance that demands reduced engine structural weight as well as higher component heat resistance. The evolution of new ultra-high-temperature composites having high-temperature resistance as well as low density that a substitute super alloy and refractory metal material has become so essential and laid the foundation for high-performance engine design. The benefits of continuous fiber- reinforced CMC with high-temperature engine designs have long been recognized as a better measure of a country’s ability to design and produce spacecraft, modern aircraft, and weapons. Ceramic matrix composites materials are used in various aircraft type engines, aircraft brake disks, high-temperature gas turbines components, slide bearing components, hot gas duct, flame holders and components for burners are made by using oxide CMCs.