Demand High Strength Research Articles

Amorphous TiO2 nano-coating on stainless steel to improve its biological response

This study delves into the potential of amorphous titanium oxide (aTiO2) nano-coating to enhance various critical aspects of non-Ti-based metallic orthopedic implants. These implants, such as medical-grade stainless steel (SS), are widely used for orthopedic devices that demand high strength and durability. The aTiO2 nano-coating, deposited via magnetron sputtering, is a unique attempt to improve the osteogenesis, the inflammatory response, and to reduce bacterial colonization on SS substrates. 
The study characterized the nanocoated surfaces (SS-a TiO2) in topography, roughness, wettability, and chemical composition. Comparative samples included uncoated SS and sandblasted/acid-etched Ti substrates (Ti). The biological effects were assessed using human mesenchymal stem cells (MSCs) and primary murine macrophages. Bacterial tests were carried out with two aerobic pathogens (S. aureus and S. epidermidis) and an anaerobic bacterial consortium representing an oral dental biofilm.
Results from this study provide strong evidence of the positive effects of the aTiO2 nano-coating on SS surfaces. The coating enhanced MSC osteoblastic differentiation and exhibited a response similar to that observed on Ti surfaces. Macrophages cultured on aTiO2 nano-coating and Ti surfaces showed comparable anti-inflammatory phenotypes. Most significantly, a reduction in bacterial colonization across tested species was observed compared to uncoated SS substrates, further supporting the potential of aTiO2 nano-coating in biomedical applications.
The findings underscore the potential of magnetron-sputtering deposition of aTiO2 nano-coating on non-Ti metallic surfaces such as medical-grade SS as a viable strategy to enhance osteoinductive factors and decrease pathogenic bacterial adhesion. This could significantly improve the performance of metallic-based biomedical devices beyond titanium.

Effect of temperature on oxidation during boriding of Ni-Hard 4

Abstract Ni-Hard 4, also known as white cast iron, is widely used in many applications that demand high mechanical strength. This material is recognized for its ability to withstand challenging conditions. In this study, surface modification processes, particularly boriding, were carried out on the material. Boriding is considered an effective process for enhancing the mechanical strength of a surface. While there are various methods for performing boriding, the pack-boriding method was chosen for this study. This method was applied in a typical heat treatment furnace. Ni-Hard 4 specimens were subjected to different combinations of temperature (1000–1200 °C) and 4 h duration, resulting in a total of three distinct samples. Subsequently, the microstructure, hardness, and chemical composition of the boride layers formed on the material’s surface were meticulously examined. As a result of the detailed analysis, it was determined that if the boriding process was carried out in a furnace without controlled atmosphere, high temperature oxidation started on the surface of Ni-Hard 4, and in this case it increased in parallel with the increase in temperature.

Achieving balanced enhancement of mechanical performance and heat resistance in Cf/SiC-superalloy joints by regulating active element Ti in brazing filler

The application of Cf/SiC-superalloy joints in aerospace typically demands high strength and good heat resistance. However, the simultaneous improvement of the two properties is a pressing problem that needs to be addressed. This paper proposes the addition of diamond (C) powder to the Cu-Ni-Ti brazing filler to regulate the interface reaction between the filler and Cf/SiC composite and the initial liquefaction temperature of the interlayer, thereby achieving a balanced enhancement in both the mechanical performance and high-temperature resistance of the Cf/SiC-GH3044 joints. The results indicate that during the joining process, a brittle compound layer composed of TiC, Ti5Si3, and Ni16Ti6Si7 is formed at the Cf/SiC/interlayer interface. The thickness of the compound layer increases with elevated joining temperatures or prolonged holding times, which is detrimental to the strength of the joint. The added C particles react with the active element Ti to synthesize in situ some TiC reinforcing particles with the low thermal expansion coefficient in the interlayer. This not only suppresses the excessive growth of the brittle compound layer but also alleviates the residual thermal stress in the joint. Additionally, since Ti is a lowering-melting element in the Cu-Ni-Ti filler, the consumption of Ti by the C/Ti reaction raises the initial liquefaction temperature of the interlayer, thus improving the heat resistance of the joint. When the joining temperature and holding time were kept constant, the shear strength of the joint reached a maximum value as the C particle content increased. If the joining temperature was elevated or the holding time was extended, the C content associated with the peak strength also increased. By optimizing the C particle content, both the shear strength and heat resistance of the joint were improved. The maximum shear strength of the joint at room temperature and 900 °C were measured to be 245 MPa and 138 MPa, respectively. Moreover, the joint exhibited a maximum temperature capability of 1064 °C.

Investigating the role of synthesized reduced graphene oxide and graphite micro-fillers on mechanical and fretting wear performance of glass fiber epoxy-based composite

In the current study, graphite was exfoliated using a Hummer’s technique to produce graphene oxide (GO), which was then reduced with hydrazine hydrate (a reducing agent) to produce reduced graphene oxide (rGO) with high purity. The XRD, FT-IR, SEM, and TGA analysis confirmed the synthesis of rGO by stating its crystal phase, chemical functional group, morphology, and thermal stability. The objective of this study is twofold: firstly, to synthesize the reduced graphene oxide (rGO) cost-effectively, and secondly, to explore its potential as an additional filler in Glass Fiber Reinforced Polymer (GFRP) composites. Aiming to enhance their overall performance. The GFRP laminate composite was fabricated through the hand layup technique by varying the concentration of Gr (i.e., 0.5 wt% & 1 wt%) and rGO (i.e., 0.5 wt% & 1 wt%). The morphological study of the fracture surface revealed a proper dispersion of filler obtained at 0.5 wt% and by increasing the concentration to 1 wt% it reveals a clustering of fillers and formation of micro-voids. The result revealed that maximum improvement has been observed in the GFRP composite having 0.5 wt% rGO composite than neat GFRP composite. Incorporation of rGO micro-filler in GFRP laminate composite significantly improved the tensile strength, flexural strength, and in their modulus by 59.56%, 18.21%, 24.45%, and 22.75% respectively compared to neat GFRP laminate composite. In the case of 0.5 wt% graphite filler demonstrates an enhancement in tensile strength, flexural strength, and their modulus by 37.98%, ∼8%, 6.64%, and ∼5% respectively. In fretting wear test reveals that 1 wt% of graphite filler has better wear resistance than all other composites. The worn morphology revealed adhesive and abrasive wear as the predominant wear mechanism. The incorporation of rGO filler in GFRP makes it a promising material for industrial applications that demand high strength and superior wear resistance.

A flexible carbon nanotube electrode array for acute in vivo EMG recordings.

Executing complex behaviors requires precise control of muscle activity. Our understanding of how the nervous system learns and controls motor skills relies on recording electromyographic (EMG) signals from multiple muscles that are engaged in the motor task. Despite recent advances in tools for monitoring and manipulating neural activity, methods for recording in situ spiking activity in muscle fibers have changed little in recent decades. Here, we introduce a novel experimental approach to recording high-resolution EMG signals using parylene-coated carbon nanotube fibers (CNTFs). These fibers are fabricated via a wet spinning process and twisted together to create a bipolar electrode. Single CNTFs are strong, extremely flexible, small in diameter (14-24 µm), and have low interface impedance. We present two designs to build bipolar electrode arrays that, due to the small size of CNTF, lead to high spatial resolution EMG recordings. To test the EMG arrays, we recorded the activity of small (4 mm length) vocal muscles in songbirds in an acute setting. CNTF arrays were more flexible and yielded multiunit/bulk EMG recordings with higher SNR compared with stainless steel wire electrodes. Furthermore, we were able to record single-unit recordings not previously reported in these small muscles. CNTF electrodes are therefore well-suited for high-resolution EMG recording in acute settings, and we present both opportunities and challenges for their application in long-term chronic recordings.NEW & NOTEWORTHY We introduce a novel approach to record high-resolution EMG signals in small muscles using extremely strong and flexible carbon nanotube fibers (CNTFs). We test their functionality in songbird vocal muscles. Acute EMG recordings successfully yielded multiunit recordings with high SNR. Furthermore, they successfully isolated single-unit spike trains from CNTF recordings. CNTF electrodes have great potential for chronic EMG studies of small, deep muscles that demand high electrode flexibility and strength.

INFLUÊNCIA DO TREINAMENTO DE RESISTÊNCIA NOS MEMBROS INFERIORES SOB A QUALIDADE EXPLOSIVA DOS ATLETAS

ABSTRACT Introduction: Athletics demands high explosive strength from its athletes, and complementary techniques are constantly implemented to maintain the competitive level of its practitioners. And is believed that resistance training can benefit track and field athletes. Objective: Explore whether lower limb resistance exercise can effectively increase the explosive quality of track and field athletes. Methods: We randomly divided 88 professional track and field athletes into experimental and control groups, who underwent training for 12 weeks. The experimental group received lower limb-specific resistance training, while the control group underwent general training. Results: After the lower limb resistance training intervention, the athletes showed evolution in the standing triple jump, from 7.63±0.179m to 7.94±0.12m. The average 30-meter running time also showed gains from 4.55±0.23s to 4.17±0.13s, and the YOYO running distance increased from 979.48± 134.11m to 1139.28±107.84m. The sitting flexion distance increased from 16.91±4.86cm to 17.65±3.39cm, and the solid ball throwing distance went from 20.03±2.05m to 21.24±2.35m. Conclusion: Lower limb resistance training can effectively improve the explosive power of professional track and field athletes. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Constructing a bimodal microstructure via cyclic thermal treatment in selective laser melted Ti6Al4V-5vol%TiB composite

Titanium matrix composites are considered promising materials in engineering fields that demand high strength and wear-resistant materials in combination with lightweight. Selective laser melting (SLM) recently has been used to fabricate TMCs, but their plasticity is generally poor as reported. Bimodal microstructures consisting of globular α are known to possess excellent comprehensive mechanical properties in Ti-based alloys. Heat treatment for the transformation of lamellar to globular microstructures is usually preceded by thermomechanical processing. This work reports a cyclic thermal treatment (CTT) for constructing a bimodal microstructure in SLM-processed Ti6Al4V-5vol%TiB composite without the need for predeformation. The CTT process involves repeated thermal cycling between 875 and 975 °C to induce notable changes in the fractions of α and β. Additionally, a β-region annealing process (1050 °C, 1 h) was designed and implemented before CTT to accelerate the globularization process. After a CTT of 10 cycles, a typical bimodal microstructure with highly spherical αp was successfully prepared. Meanwhile, the segregated TiB whisker clusters were significantly replaced by uniformly distributed individual TiB whiskers. Boundary splitting and termination migration are two competing mechanisms in the globularization process. TiB whiskers promote the globularization process through repeated heterogeneous nucleation in the cooling part. Compressive testing suggested that the sample with a bimodal microstructure (54.5% αp) exhibited improved plasticity (12.3%–27.3%) at the cost of acceptable yield strength reduction (1743 MPa–1392 MPa), which is desirable for structural applications.

Fabrication and Characterization of Gelatin/Polyvinyl Alcohol Composite Scaffold.

In this study, porous scaffold materials based on polyvinyl alcohol (PVA) and gelatin (Gel) were successfully fabricated and characterized. The mechanism of the reaction, morphology, and crystallinity were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In addition, thermogravimetric analysis (TGA) was performed together with differential scanning calorimetry (DSC) for examining the thermostability and phase transformation of the scaffolds. Degradation and swelling studies of PVA/Gel composite scaffold materials were performed in phosphate-buffered saline. Finally, the mechanical performances had been determined. According to the results, the polymer matrix that was formed by the combination of PVA and gelatin had better thermal stability. The synthesized composite scaffold was amorphous in nature. The addition of gelatin did not affect the fishbone-like microstructure of PVA, which ensures the excellent mechanical properties of the PVA scaffold. The denaturation temperature and elastic modulus of the PVA scaffold were improved by the gelatin addition, but the physical and chemical properties of the PVA scaffold were weakened when the gelatin content exceeded 10%. In addition, the PVA-10G sample has suitable degradability. Therefore, the PVA/Gel composite scaffold might potentially be applied in the field of tissue engineering that demands high strength.

Effect of fiber content and their hybridization on bending and torsional strength of hybrid epoxy composites reinforced with carbon and sugar palm fibers

This study aims to investigate the effect of fiber hybridization of sugar palm yarn fiber with carbon fiber reinforced epoxy composites. In this work, sugar palm yarn composites were reinforced with epoxy at varying fiber loads of 5, 10, 15, and 20 wt % using the hand lay-up process. The hybrid composites were fabricated from two types of fabric: sugar palm yarn of 250 tex and carbon fiber as the reinforcements, and epoxy resin as the matrix. The ratios of 85 : 15 and 80 : 20 were selected for the ratio between the matrix and reinforcement in the hybrid composite. The ratios of 50 : 50 and 60 : 40 were selected for the ratio between sugar palm yarn and carbon fiber. The mechanical properties of the composites were characterized according to the flexural test (ASTM D790) and torsion test (ASTM D5279). It was found that the increasing flexural and torsion properties of the non-hybrid composite at fiber loading of 15 wt % were 7.40% and 75.61%, respectively, compared to other fiber loading composites. For hybrid composites, the experimental results reveal that the highest flexural and torsion properties were achieved at the ratio of 85/15 reinforcement and 60/40 for the fiber ratio of hybrid sugar palm yarn/carbon fiber-reinforced composites. The results from this study suggest that the hybrid composite has a better performance regarding both flexural and torsion properties. The different ratio between matrix and reinforcement has a significant effect on the performance of sugar palm composites. It can be concluded that this type of composite can be utilized for beam, construction applications, and automotive components that demand high flexural strength and high torsional forces.

Development of high performance sustainable optimized fiber reinforced geopolymer concrete and prediction of compressive strength

Geopolymer concrete is the sustainable building material that can be used as an alternative for cement concrete. There are several factors that affect the property of geopolymer concrete such as type of binder material used, molarity of activator solution and curing condition. The frailty of practical application of geopolymer concrete lies in its brittle nature. The main objective of this work focuses towards the synthesis of high impact strength fiber reinforced geopolymer concrete by optimizing various factors that affect its strength and reduce its brittleness. The novelty of the work lies in the approach of augmentation of high modulus glass fibers over the optimized Geopolymer concrete. In the current investigation, extensive experimental works were conducted to optimize the molarity of alkaline solution, utilization of Ground Granulated Blast Furnace Slag and glass fiber in geopolymer concrete under different curing condition. Further Microstructural investigation through Scanning Electron Microscopic analysis and Energy Dispersive Spectroscopy analysis was carried over to understand the microstructure of the geopolymer matrix. An exhaustive and meticulous discussion part is included to elaborate the influence of molarity, curing condition, Ground Granulated Blast Furnace Slag utilization and incorporation of fibers in to the geopolymer matrix. Analytical Investigation though Artificial Neural Network has been performed to predict the compressive strength of the fiber reinforced geopolymer concrete based on three different input conditions. This study reported the optimum molarity of sodium hydroxide as 13M and optimum utilization of GGBS slag as 100 percent under ambient curing and 20 percent under heat curing. Further the work reported significant increase of about ten times in the energy absorption capacity and considerable decrease over the brittleness of the geopolymer concrete with the utilization of glass fiber. This research work could pave way for the development of high performance sustainable geopolymer concrete under ambient curing condition enabling the application of application of geopolymer concrete in industry that demand high impact strength materials such as machine foundations, pile caps, spill ways. This concrete could pave way for replacing conventional concrete in all its existing applications.

Fatigue behavior and osseointegration of porous Ti-6Al-4V scaffolds with dense core for dental application

Increasing research has supported the utilization of a porous Ti-6Al-4V (T64) scaffold for dental applications because of its low stiffness and well-constructed pore structure that allows for bone ingrowth. Selective laser melting (SLM) has enabled the fabrication of T64 lattice structures, but most studies indicate limited fatigue performance. In this study, porous scaffolds with dense cores of varying diameter were designed in order to test their effectiveness in enhancing the strength of the scaffold. The static mechanical properties and fatigue performance of the resulting SLM-printed T64 porous structures were systematically examined. The mechanisms of this design were analyzed using finite element (FE) simulation, and osseointegration responses were investigated by in vitro and in vivo tests. Our design was found to effectively balance the biological requirements (low stiffness and high porosity) and mechanical demands (high yield strength and high fatigue strength) of the SLM-fabricated T64 lattice structure, and shows good potential for application in dental implants.

Microstructures and Mechanical Properties of Dissimilar Metal Gas Tungsten Arc Welds of 15CDV6 Steel and AISI 304 Stainless Steel

The pressure pipeline applications demand high strength steels and stainless steels based on the requirement of strength and corrosion point of view, respectively. Welding is one of the widely practiced metal joining techniques in such kind of applications due to the high-pressure environment. The present work is primarily aimed at understanding the feasibility and producing X-ray radiography quality gas tungsten arc welds of dissimilar steels, particularly, 15CDV6 steel and AISI 304 stainless steel. The sound dissimilar GTA welds are subjected to evaluation of microstructures, mechanical properties such as microhardness across the weldment and tensile properties. The mechanical properties are further correlated to microstructures of dissimilar weld joints. The filler wire material has profound influence on the microstructures and mechanical properties (both tensile strength and hardness) of dissimilar steel weld joints. The dissimilar weld made with 8CD12 filler wire demonstrated higher tensile strength and joint efficiency as compared to the dissimilar weld made with ER 308L filler wire.

Structure and Properties of Layered Ti-6Al-4V-Based Materials Fabricated Using Blended Elemental Powder Metallurgy

Due to the high specific strength of Ti, materials on its base are indispensable when high-strength and low-weight requests are a chief demand from the industry. Reinforcement of Ti-alloys with hard and light particles of TiC and TiB is a credible pathway to make metal matrix composites (MMC) with enhanced elastic moduli without compromising the material’s low-weight. However, reinforcement of the alloy with hard particles inevitably lowers the value of toughness and plasticity of material. Yet, in many applications simultaneous high hardness and high plasticity are not required through the entire structure. For instance, parts that need enhanced wear resistance or resistance upon ballistic impact demand high hardness and strength at the surface, whereas their core necessitates rather high toughness and ductility. Such combination of mechanical properties can be achieved on layered structures joining two and more layers of different materials with different chemical composition and/or microstructure within each individual layer.Multi-layered structures of Ti-6Al-4V alloy and its metal-matrix composites (MMC) with 5 and10% (vol.) of TiC and TiB were fabricated in this study using blended elemental powder metallurgy (BEPM) of hydrogenated Ti. Post-sintering hot deformation and annealing were sometimes also employed to improve the microstructure and properties. Structure of materials were characterized using light optical microscopy, scanning electron microscopy, electron backscattered diffraction, x-ray microscopy, tensile and 3-point flexural tests. The effect of various fabrication parameters was investigated to achieve desirable microstructure and properties of layered materials. Using optimized processing parameters, relatively large multilayered plates were made via BEPM and demonstrate superior anti-ballistic performance compared to the equally sized uniform Ti-6Al-4V plates fabricated by traditional ingot and wrought technology.

Static analysis on Malaysian Yankee’s pineapple leaf fiber/epoxy composite

The static analysis on pineapple leaf fibre (PALF) reinforced epoxy composites was carried out in this study. The effect of fiber alignment in X and Y axis were studied while maintaining total fiber loading of 10% by weight. The bending and compression strength were analyzed by performing flexural and compression test. The composite properties was strongly influence by the fiber orientation where Y axis shows improvement about 97% in bending and 5.3% in compressive strength compared to neat epoxy. However, as for X orientation bending test shows lower bending strength compared to neat epoxy but improve 4% in compressive strength. It can be concludedthat the fiber alignment in Y-direction is more suitable to be utilized for automotive interior or household applications that demand high strength properties.

Effect of post weld heat treatment and welding parameters on mechanical and corrosion characteristics of friction stir welded aluminium alloy AA2014-T6

This paper addresses the effect of post weld heat treatment methods on the mechanical and corrosion characteristics of friction stir welded aluminum alloy AA2014-T6. Aluminum alloy AA2014 is mainly used in applications that demand high strength to weight ratios, such as aerospace, marine, and industrial applications. In this work, AA2014-T6 plates of 6 mm thick were butt welded using a tool with a square profile. Tensile strength, hardness, and corrosion characteristics were compared between the samples as welded and post weld heat treated. Welded samples that were heat treated for a shorter ageing period (8 h) showed improved tensile strength irrespective of welding process parameters, compared to as-welded samples. The samples heat treated for a longer ageing period (9 h) showed a decline in tensile strength for low tool rotation speed. Hardness increased in welded samples heat treated for 8 h. Welded samples heat treated for 9 h show high passivity in corrosion media.

Preparation, development, outcomes, and application versatility of carbon fiber-based polymer composites: a review

The high strength to weight ratio of carbon fiber has made it as an attractive energy-saving material over the conventional strength-bearing materials like steel. Realizing the trend, the high-weight steel is being progressively replaced by the low-weight and corrosion-resistant carbon fiber composites in many strength applications. The carbon fiber-reinforced polymer matrix composite (PMC) have thereby become forefront material in aerospace, automobile, sporting goods, and other applications which demand high strength and high modulus. Moreover, the gradual reduction of its cost curtsy to the extensive research in the field of carbon fiber technology in recent years has been opened its market in different construction applications. This review is the discussion of carbon fiber loaded a variety of polymer matrix composites where the structural importance of these composites has been emphasized. The objective of this discussion is to provide information on the whole spectrum of carbon fiber-based polymeric composites. It also includes brief discussion about preparation and properties of carbon fibers along with processing, fabrication, and structural applications of these carbon fiber-based polymer composites.

A data-driven programming of the human-computer interactions for modeling a collaborative manufacturing system of hypoid gears by considering both geometric and physical performances

Abstract Hypoid gears are widely used in transmission systems, which demands low noise and high strength for their hypoid gears. To meet those demands, it is significant to consider the geometric and physical performances of hypoid gears. To obtain the optimal performances, a collaborative manufacturing system of hypoid gears is composed of three interrelated processes: gear machining, measurement and modification. Since each of these three processes is complicated, the modeling of the collaborative manufacturing system is very difficult, especially when human-computer interaction (HCI) is needed in each process. To fulfill this problem, a data-driven programming for HCIs in the collaborative manufacturing system is proposed. For modeling each of those three processes, the data-driven programming is applied to describe the HCI in each process. Subsequently, the collaborative manufacturing system is modeled with full consideration of both geometric and physical performances. To solve this model, a Levenberg-Marquardt algorithm with a trust region strategy is employed to obtain a stable numerical solution. A numerical instance is given to show the validity of the proposed method.

Effects of Equal Channel Angular Extrusion (ECAE) Process on the Mechanical Property and Erosion Resistance of Ti–5Al–5Mo–5V–3Cr Alloy

High-strength near-β-phase titanium alloys, including Ti–5Al–5Mo–5V–3Cr, are considered the material of choice for large components that demand weight reduction and high strength. The erosion resistance of Ti–5Al–5Mo–5V–3Cr alloy is essential for many components exposed to solid particles and marine environment, but is rarely investigated. In this study, we investigate the erosion resistance and mechanical properties of Ti–5Al–5Mo–5V–3Cr alloy against silica slurry, which is formed by an equal channel angular extrusion (ECAE) process in β-phase temperature range, followed by quenching and annealing treatments. It was found that ECAE and subsequent heat treatments promote the precipitation of extremely fine α-phase particles inside β-phase grains, which lead to increased tensile strength and elongation due to the function of the α-precipitates as obstacles for dislocation sliding and the refined β-grains that avoid the stress propagation. Both the fracture toughness and impact toughness are improved as measured by the tensile test and impact test. The erosion mechanisms were analysed by the morphological analyses of the eroded surfaces, while the material microstructures were observed by a scanning electron microscope, which proved the existence of fine α-precipitates in the β-phase. Erosion resistance test was conducted, and mass loss was measured in comparison with non-ECAE-treated sample.

Microstructure Control of Non-quenched and Tempered CT80 Grade Coiled Tubing Steel

Complex working condition of coiled tube (CT) steel demands high strength and low ratio of yield strength (YS) to tensile strength (TS). Reasonable microstructure control is a key problem of CT steel. Controlled rolling and controlled cooling experiments were carried out by two kinds of tested steels with different chemical compositions to develop the non-quenched and tempered CT80 steel. Mechanical properties of the tested steels at different processes are all in good agreement with the properties requirement of CT80. Increasing of Mo and Nb contents improves transformation of acicular ferrite and martensite–austenite (M–A) islands. 4 vol% of fine M/A islands increase TS and decreases ratio of YS/TS. Cooling rate increasing also improves acicular ferrite transformation and enhances TS, but has little effect on ratio of YS/TS. To meet the requirement of high strength and low ratio of YS/TS, optimized complex microstructure of the CT80 steel is composed of acicular ferrite, about 30 vol% of bainite and 4 vol% of M–A islands.

Influence of Pellet Basicity (CaO/SiO2) on Iron Ore Pellet Properties and Microstructure

In JSW steel limited Pellets form the major part of the iron bearing feed to Corex and Blast Furnace. These two iron making units demand high strength, lower reduction degradation index pellets to maintain good permeability of the bed to achieve high productivity and lower fuel rate. To produce good quality of pellets certain additives are important. JSWSL produces basic pellets with basicity (CaO/SiO2) 0.40 to 0.50. The quality of the pellet is affected by the type of the raw materials, gangue content, and flux proportion and their subsequent treatment to produce pellets. The limestone addition, i.e. basicity–CaO/SiO2 of pellet decides the mode, temperature and the amount of melt formed. The properties of the pellets are, therefore, largely governed by the form and degree of bonding achieved between ore particles and also by the stability of these bonding phases during the reduction of iron oxides. Hence in production of acid, basic and fluxed pellets, characterization of the bonding and crystalline phases is of prime importance in understanding the basis for the production of pellets of desired quality. To understand the influence of limestone addition (basicity) on iron ore pellets microstructural, physical and metallurgical properties basket trials have been carried out with different level of basicity from 0.08 to 1.15. From the test result it was clear that pellet properties were influenced by the bonding phases present in the pellet. The tumbler index increased from 93.15 to 95.38% and cold crushing strength increased from 176 to 264 kg/p with increase in pellet basicity from 0.08 to 1.15. This effects result from microstructural differences appeared from the flux addition. RDI of the pellet decreased initially from 16.3 to 10.9% in the pellet basicty range from 0.08 to 0.33 and again increased from 10.9 to 13.6 with increase in pellet basicty from 0.33 to 1.15. This effect is due to the change in structural properties of the pellet during reduction. Pellet with basicity 0.33 showed good physical as well metallurgical properties due to bonding phases present in the pellets.