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In present work, Aluminium matrix composites reinforced with x wt.% SiC (x = 5, 7.5 and 10) microparticles were synthesised by powder metallurgy route. The microhardness (VHN) of the Al/SiC composites were investigated using Response Surface Methodology (RSM) and artificial neural network (ANN) approach. Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Elemental mapping and Optical microscopy were done for the microstructural investigations. The X-ray diffraction (XRD) analysis was done for received powders and composites samples for phase recognition and existence of reinforcement particles (SiC) in the synthesised sintered composites. The design of experiments based on RSM was utilised following the central composite design method. Empirical models have been developed by considering variance analysis (ANOVA), to establish relationships among the control factors and the response variables. A feed-forward back-propagation neural network (FF-BPNN) was used to determine the qualitative characteristics of the process, and the accuracy of the BPNN system was attributed with mathematical models based on RSM model. The ANN model predicted surface hardness values are near the experimental findings. It is established that the developed models can be used to predict the hardness of the surface within the investigation range. The composite with reinforcement 7.5% revealed higher sintered density and Vickers microhardness due to the uniform distribution of filler particles in the Al matrix featuring no pores. The results indicate overall higher accuracy in the ANN method than RSM model.

Gears for structural machine require high fatigue strength for high performance. Generally, gears made of carbon steel worn and corroded easily thus the useful lifetime of the gears became short. This project aimed to increase the hardness and corrosion resistance of carbon steel gear by heat treatment method which was nitriding consisting of 95% nitrogen gas as well as 5% hydrogen gas and to investigate its properties after nitriding. In this project, gas nitriding process was chosen to be conducted to increase the hardness and corrosion resistance of gears at two different tube furnace temperatures: low (550°C) and high (1150°C), both for four hours. Microstructural and mechanical property evaluation of the low and high temperature nitrided low- carbon steel or also known as mild steel BS970-080A15 were studied and the results were compared to identify which gear has better performance in terms of hardness as well as corrosion resistance. From this experiment, the high-temperature nitrided carbon steel had improved its hardness by 113.18% which was from HV233.6 to HV498 in average compared to the raw carbon steel but in low temperature, the hardness only increased by 19.69%. Meanwhile, the corrosion rate of high-temperature nitrided carbon steel when compared to the raw material displayed a reduction of 56.67% from 0.1637 to 0.07095 millimeter per year while the corrosion rate in the low temperature reduced by 43.33%. The results from Vickers hardness test and weight loss analysis proved that high-temperature nitrided carbon steel was greater in hardness and corrosion resistance than the low-temperature nitrided carbon steel thus the lifetime and corrosion resistance of gears made of carbon steel were enhanced by nitriding.

In this decade additive manufacturing is playing a vital role in fabrication of various types of industrial equipment. 3D printing is a computer-aided design process offering various advantages that increase the market size for nanosensor smart manufacturing. Nanotechnology provides an advanced platform to improve the sensing properties of sensors, due to the larger surface area than that of microsensors. This chapter describes the fundamentals of 3D printing as well as nanotechnology applications for nanosensors. Various 3D printed nanosensors including physical sensors, biosensors, and chemical sensors are discussed. By incorporating 3D printing, many more complex shapes of nanosensors can be easily formed. Research is ongoing to improve the attributes of nanosensor fabrication as well as decrease the cost of the 3D printed nanosensors.

Materials play a significant role in daily life and have contributed greatly to the technoeconomic advancement of the modern era. Biocomposites are considered newly developed fourth-generation materials that are considerably high performance and desirable in the light of environmental sustainability and full end-use consumer product degradability. Biocomposites derived via renewable resources offer very interesting potential to benefit manufacturers, the surrounding environment, and consumers as petroleum resources are deteriorating rapidly. This chapter presents an overview of some basic concepts of biocomposite materials and their potential applications in automotive industries. It also addresses the recent advances, current initiatives, and key limitations to be tackled for the implementation of biocomposites at the commercial scale. Moreover, the economic and environmental consequences of biocomposites in the automotive sector are also highlighted in detail. A retrospective review of market trends and forecast analysis of biocomposites has also been addressed and discussed. The study also highlights the potential of natural fibers and biopolymers for commercial applications in the interior and exterior components of cars and a few other applications as well.

The aim of this study was to characterize the adhesion bonding of intumescent coating and the primer on steel substrate with respect to its mechanical, physical and chemical properties, before and after a fire test. The coated steel substrates were subjected to fire in a furnace at 950 °C for various durations ranging from 30, 45, and 90 to 120 min. The coatings were characterized by Thermogravimetric Analysis (TGA) while the char from fire test was characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR). For mechanical properties, the shear strength of the intumescent coating was measured for various coating thicknesses ranging from 1, 2, 3, 4, 10 to 22 mm through lap shear test. The changes in the adhesion bonding of the coatings, primer, and char with steel substrate microstructure were monitored using SEM. The microstructure observation indicated a profound mechanical interlocking mechanism between the primer coating and the steel substrate. Despite the two-hour fire test, the temperature of the steel substrate remained below 100 °C and no re-crystallization was observed. A considerable decrease in shear strength of the intumescent coating, primer and steel substrate from 1.95 MPa to 0.23 MPa was also measured as the thickness of the coating substrate was increased from 1 mm to 22 mm, respectively.

The multilayer coatings of Chromium (Cr), Chromium Nitride (CrN), Chromium Carbonitride (CrCN) and Zirconium Nitride (ZrN) have been deposited onto stainless steel substrates by using the Physival Vapour Deposition (PVD) technique. X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and pin-on-disc tribometer were employed to examine phase detection, cross-section images and tribological properties respectively. In this work, the tribological performance was studied for multilayer coatings deposited at 5 minutes and 10 minutes compared with the uncoated sample. Multilayers of Cr, CrN, CrCN, and ZrN have been successfully deposited onto stainless steel substrates by PVD. XRD analysis detected major peak in preferred orientation. Multilayer fabricated at 10 minutes deposition time showed best tribological performance with lower friction coefficient, lower alumina ball mass loss and lower wear track width.

This study presents the influences of talc as an additive in intumescent coating formulations on the thermal insulation, degradation and water resistance. The fire test was performed according to ASTM-E119 standard to study the heat shielding properties of the coated substrates. The results showed that the 20% of the talc enhanced the heat shielding and recorded substrate temperature 75 °C after 100 min of fire test. The morphology of the char was analyzed by Scanning Electron Microscopy (SEM). X-ray fluorescence (XRF), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) results showed the presence of P 2 O 5 , MgO, TiO 2 , and SiO 2 respectively. The functional groups analysis of char confirmed the presence of high temperature compounds and enhanced thermal performance of coatings. Thermogravimetric analysis (TGA) showed that addition of 20% talc increased residual mass of the char by 55.55%. The lap shear test result showed that the talc also improved the adhesion of the intumescent coating with steel substrate and the highest shear strength observed was 7 MPa for a formulation, F5 containing 20% talc. Water immersion test was performed according to ASTM D870-15 and the results showed the higher water-resistance was recorded for a formulation containing 10% talc in the control formulation.

The addition of inorganic spherical nanoparticles fillers to polymers matrix enables in the enhancement in the polymer’s mechanical properties as well as the addition of new features in the polymer matrix. In the present study, ZnO/polystyrene composite was synthesized by bulk polymerization route and the hardness of composites was studied. The prepared nanocomposites were injected into a compression mold in a compression-molding machine. The prepared test specimen was subjected to Rockwell hardness tests. Further, to ensure proper morphology of nanocomposites, scanning electron microscopy (SEM) and X-ray diffraction (XRD) were carried out. Results revealed that by increasing nano-ZnO up to 0.3%, there is a remarkable increment approximately 47% in the hardness. Also, an analysis of variance (ANOVA) has been applied to find the optimal input parameter levels and to analyze the effect of these parameters on hardness. The composite produced is envisioned to have applications as the building blocks for the manufacturing of various automotive parts, sensors, transducers, actuators, UV detectors, and optoelectronic devices.

The diffusion bonding is one of the methods used to join dissimilar metals. Specimens of duplex stainless steel and low carbon steel were joined by diffusion bonding under varied temperature and holding time. The specimens were clamped using jigs and heated in a furnace. Tensile test was performed on the joined samples. The effect of bonding time and holding temperature on tensile strength and quality of the diffusion bonds were observed. Tensile strength of the joints was examined and the highest tensile strength of 116.12 MPa are obtained at temperatures of 900 °C and holding time of 180 min.

As the demand to weld higher strength materials through friction stir welding (FSW) increases, the need for better non-consumable rotating tool also increases as it has to be able to endure high frictional and thermal deformation while the work-piece undergoes intense plastic deformation at high temperatures. Carbon-based nanomaterials are good options to increase strength of steel. An attempt to improve the friction stir welding tool through carbon-based coatings on H13 tool steel has been carried out. This paper highlights the characterization of the carbon-based coatings in regard to selected coating parameters through Field emission scanning electron microscope, energy dispersive spectroscopy, Raman Spectra, and X-Ray photoelectron spectroscopy techniques. The analysis shows presence of graphite like structures whereas Carbon Nanotubes (CNT) was observed to be grown uniformly on the surface.

Shafts are rotating elements that are subjected to torsion and bending moments that cause failures at times leading to personal injury, capacity loss, or poor product quality if basic preventive design actions are not taken. Against this background, this paper describes the failure analysis and root cause of a broken SA564 grade stainless steel pump shaft used in a plant through visual inspection, metallography, X-ray diffraction, scanning electron microscope, chemical analysis, hardness, tensile and non-destructive tests. The results show that creep, fatigue initiation and propagation from defects in the material during the operation were the predominant factors of pump shaft failure. Moreover, the existence of voids, micro-cracks, sensitisation and creeps were also identified on the broken shaft. Overall, the studied broken shaft of the impeller failed due to fatigue, initiated at the fillet radius of the keyway due to the high cyclic stress loading.

In this research, diffusion bonding was carried out to produce transition joints between mild steel A36 (Fe A36) and aluminium Al 5083 (AA5083) with the presence of gallium (Ga) as an interlayer between the two faying surfaces. The microstructural development and interfacial growth of intermetallic compounds at the interface layer between Fe A36 and AA5083 after the diffusion bonding process were investigated. The joining was performed by clamping the two materials with a Ga interlayer and then heated in a furnace. The interlayer developed from this diffusion heating in air condition provides an average thickness of 30 &mu, m. Characterization of intermetallic compounds was conducted using SEM-EDX and XRD. The results showed that SEM-EDX confirmed the occurrence of interdiffusion of elements from Fe A36 and AA5083 present at interlayer. XRD analysis reveals the formation of Fe3Al at the diffusion layer.

Experimental data of thermal conductivity, thermal stability, specific heat capacity, viscosity, UV&ndash, vis (light transmittance) and FTIR (light absorption) of Multiwalled Carbon Nanotubes (MWCNTs) dispersed in glycols, alcohols and water with the addition of sodium dodecylbenzene sulfonate (SDBS) surfactant for 0.5 wt % concentration along a temperature range of 25 &deg, C to 200 &deg, C were verified using Artificial Neural Networks (ANNs). In this research, an ANN approach was proposed using experimental datasets to predict the relative thermophysical properties of the tested nanofluids in the available literature. Throughout the designed network, 65% and 25% of data points were comprehended in the training and testing set while the other 10% was utilized as a validation set. The parameters such as temperature, concentration, size and time were considered as inputs while the thermophysical properties were considered as outputs to develop ANN models of further predictions with unseen datasets. The results found to be satisfactory as the (coefficient of determination) R2 values are close to 1.0. The predicted results of the nanofluids&rsquo, thermophysical properties were then validated with experimental dataset values. The validation plots of all individual samples for all properties were graphically generated. A comparison study was conducted for the robustness of the proposed approach. This work may help to reduce the experimental time and cost in the future.

The main source of the heat generation during the Friction Stir Welding (FSW) is the friction force between tool and workpiece and the plastic deformation. The geometry of the tool including the pin and the shoulder highly affects the friction force. In this study, the effects of different pin profiles with different rotational and traversing speed are evaluated in order to obtain the optimum pin profile using heat generation and tensile strength. Three different rotational speed and welding speeds are applied with threaded cylindrical, conical, stepped conical and square pin profiles. Thermocouples K type have been embedded in order to record the temperature during the welding at the advancing and the retreating side. Moreover, tensile test and microstructure analysis are performed in order to study the microstructure. The results of experimental process and design of experiments are correlated well. The better joint produced with threaded cylindrical tool pin profile with rotation speed of 1600 rpm and welding speed of 40 mm/min.

In the past years, not many works on joining sialon to martensitic stainless steel have been carried out. The effect of the cut off heat upon cooling on the joint has yet to be discussed. In this paper, this effect is studied in terms of the microstructure and hardness of the reaction layer. Diffusion bonding was utilized to join sialon and AISI 420 martensitic stainless steel. The joining processes were conducted at 1150°C and 1200°C for one hour under a uniaxial pressure of 17 MPa in a vacuum (i.e. 1.0x10-5Torr). The heat was cut off upon cooling and the samples were left in the furnace for about 20 hours to cool down. Thicker reaction layer was formed in 1200°C sample because interdiffusion and reaction of elements occurred more rapidly at this temperature. The cut off heat had caused the sialons to crack and it was very severe in 1150°C sample due to the formation of a very thin interface layer. This layer did not have the sufficient strength to bind sialon and steel together because one of the sialons was completely detached from the joint. Diffusion layer and parent steel were segregated due to the difference in properties between the regions and it was more noticeable in 1200°C sample. Iron silicides and aluminium oxide might be formed in the interface layer. Microstructure of the parent steel transformed from globular coarse carbide in ferrite matrix to large grain size with carbide’s precipitation along the grain boundaries. More precipitates were formed in 1200°C sample and they were concentrated near the segregation line of the diffusion layer and the parent steel. The weakest part of the joint was at the border of sialon and interface layer since their hardness were extremely different.

Joining of duplex stainless steel (DSS) and low carbon steel (LCS) was performed using gas tungsten arc welding (GTAW) with aid of argon as a shielding gas. Sample was welded using ER308L weld wire to produce joined material. Physical and mechanical properties of the heat effect zone and the welded joint were investigated using optical microscope (OP), scanning electron microscope (SEM), Electron dispersive spectroscopy (EDS), hardness test and ultimate tensile test (UTS). SEM at the both sides of HAZ revealed difference in morphological changes at DSS HAZ and LCS HAZ with a precipitation of martensitic phase and chromium carbide respectively which are suspected to be responsible variation in mechanical properties at this region. UTS conducted also shows a plastic deformation mode of failure at the DSS HAZ while failure occurred at the HAZ of LCS indicating brittle property at this point. Redistribution and migration of manganese from DSS to LCS during welding from EDS is also suspected to be the reason for brittle property of HAZ of LCS

Joining sialon to as-received and nitrided AISI 420 martensitic stainless steels using diffusion bonding is reported in this paper. The samples were joined at 1200°C for one hour under uniaxial pressure of 17 MPa in a vacuum (1x10-5 Torr). After joining process, the microstructure, interdiffusion of elements, and hardness of the joint were studied. The interdiffusion and reactivity of the elements created the reaction layer. It consisted of interface layer on the sialon side whereas thicker diffusion layer was formed on the steel side. Thinner reaction layers were observed in joining sialon to nitrided steels compared to joining sialon to as-received steel due to less reactivity between the joined materials. However, more precipitates such as carbides were formed in the parent steel with longer nitriding time. Gaps were formed between the diffusion layer and the parent steel but the interfacial bonds were strong since no cracking occurred on the samples. Since the reaction layer had intermediate hardness, it contributed to the joint’s ductility that reduced the effect of thermal expansion mismatch between the joined materials by acting as a shock absorbing zone.

The objective of this work was to examine the microstructure, interdiffusion of elements, and hardness of joining sialon to AISI 420 martensitic stainless steel using diffusion bonding process. These materials were diffusion bonded at 1200oC for one hour under 20 MPa in a vacuum of 2.1x10-6 Torr. The microstructural analyses showed that joining sialon to nitrided steel produced thinner reaction layers and no gap or crack were formed on the sample. Gaps were produced in joining sialon to as-received steel. From the elemental analyses, alumina and iron silicides were formed at the interface layer of sialon/as-received steel joint. Alumina and smaller amount of silicides were detected at the interface layer of sialon/nitrided steel joint. Diffusion layer and parent steel of the sialon/nitrided steel joining contained nitrides. The hardness test across the joints indicated that reaction layers possessed intermediate hardness between sialon and steel. The layers contributed to ductility of the joint that help to attain the joint.

This paper presents the work done for the preparation of precursor for producing Ti-Al-V-Y alloy via FFC Cambridge process. The aim of the work is also to investigate the uniformity of the phases formed during the pre-processing of the precursor.The importance of the alloy for mechanical and medical applications is well known. Titanium oxide (TiO2), vanadium oxide (V2O5), aluminium oxide (Al2O3) and yttrium oxide (Y2O3) were selected as raw materials for precursor. The expected composition for the new alloy is Ti-6Al-4V-0.5Y. Water was used as a binder for the precursor. The materials were pre-mixed by ball milling for 24 hours and pressed using 13 mm die. The pressed mixtures were then sintered in the furnace at 900°C for 24 hours. The sintered samples were analysed using the optical microscope, electron micrograph with EDX and XRD. The result of the optical micrograph showed that the raw materials were uniformly mixed and well distributed with the presence of porosities. Electron micrograph further verified the morphology of the materials and the elements distribution in the precursor. The overlapping of yttrium and vanadium, Y(VO4) was observed and verified by XRD. The derived formulated precursor was then ready for further work of reduction to Ti-Al-V-Y alloy using FFC Cambridge process.

Friction stir welding (FSW) is a solid state joining process where the joint occurs below the melting point of the base metal. Recently, not only soft materials but also high melting materials have been given an attention in FSW research activities. There are many studies on high melting materials such as steel, titanium, and inconel. There are different parameters which contribute to the joint quality. Many researchers have studied on the traverse and rotational speeds as the main process parameters in order to obtain optimum weld quality. Tool geometry is another important parameter that has an influence on the weld quality. This paper aims to review the development of various pin profiles and its effects to the microstructure and mechanical properties of the weld joint. Based on the published papers, square pin profile produced sound joints. However, in other studies threaded cylinder or threaded taper provides better joints. Above all, there is an equal result among all studies in which threaded shapes are most effective on tool performance.

Duplex stainless steel (DSS) which has a dual nature of ferrite and austenite with nearly equal ratio has found a good application in oil and gas industries because of its excellent corrosion resistance, high yield strength, good weldability, and relative low life cycle costing from reduced operating cost. Dual phases of DSS or combination of two-phase existence to be more characterize with better mechanical properties than a single-phase metal of ferrite or austenite. Nitrogen is a good strengthening alloy for DSS because it forms a solid solution of (Fe, Cr)2N which is responsible for the hardness and wear resistance in DSS. Spontaneous formation of oxide or passivated layer is responsible for shield and direct exposure of surface of stainless steel to corrosive medium though is susceptible to depletion and deterioration in high chlorine water and low pH level in production environment. Total damage of passivated region on the surface of DSS prompts initiation of localized defect such as pit which grows over a time to form crack. Oil and gas environment is characterized with high H2S content which is a constraint in application of DSS in this environment because of its insignificant resistance to sulfide stress corrosion cracking (SSCC) and hydrogen-induced cracking (HIC).

Stainless steel is widely used where corrosion resistance is importance. Stainless steel has its origin excellent corrosion resistance due to the nature of presence Cr as alloying element to form stable passive layer that protects the steel. Due to its inherent austenitic structure, this material has relatively low hardness as well as poor wear resistance which hinders a wider applicability of the material and may cause problems in existing applications. The gaseous thermochemical treatments to improve surface properties of material are typically carried out in carbon and/or nitrogen bearing gases and usually associated with temperature above 500 °C.

A process based on powder metallurgy approach was developed to produce open celled aluminium foam. In the preparation of foam specimens, the Al powder and the NaCl (leaching agent) were dry mixed together in order to prepare a homogeneous mixture. The blended mixture was then subjected to pressure assisted sintering in which a pressure beyond atmospheric level is externally applied to the specimen during high frequency induction heated sintering. The embedded leaching agent was then dissolved in order to leave behind an open celled Al with the same chemical composition as that of the original Al powder. The final material is highly porous and has an interconnected porosity network. The structure of the resulting material has three levels of porosity (i.e. main cells, windows and microporosity). The X-ray diffraction analysis shows that, as the content of NaCl is increased to the volume fraction of 60%, no traces of NaCl presents in the foam.

Diffusion bonding of sialon and 7.5%-Cr Ferritic Steel (FS) in as-received and nitrided condition was studied. Decomposition of sialon and interdiffusion of elements between the sialon and the steel were observed. The interdiffusion of elements produced reaction layers at the joint. The steel moved into the decomposition part of the sialon and replaced the decomposed sialon in this part. Diffusion of silicon into the steel resulted in the silicon-diffusion layer. FeSi2 was formed in the reaction layer when Si in the decomposition part of the sialon reacted with Fe. The use of nitrided steel in the diffusion bonding had suppressed the formation of the FeSi2 in the layer.

This paper discusses the improvement made by pressure assisted sintering dissolution process (PASDP) as opposed to the solid-state sintering dissolution process (SSSDP) which was used in producing a much improved open celled aluminium foam. The improvements leads to an aluminium foam possessing a high dense of cell wall which is attainable in a much shorter time and possesses superior mechanical properties. By varying the local sodium chloride (NaCl) volume fractions in the sodium chloride/aluminium (NaCl/Al) compact, it is possible to fabricate aluminium foam with different relative densities. When subjected to monotonic compression mode, the fabricated aluminium foam exhibits typical stress–strain behaviour of metallic foam. The principles of Taguchi's Design of Experiments were employed to optimize processing factors for the fabrication of aluminium foam. Results were analysed based on Taguchi's signal to noise ratio (S/N) and analysis of variance (ANOVA) techniques in order to obtain the optimum combination of process parameter settings. Results indicate that the most notable factor influencing the fabrication of Al foam was the compaction at elevated temperature, followed by temperature, time and the process heating rate. The optimum processing parameters for the PASDP process were then predicted based on these results.

Ferritic stainless steel has low properties of wear resistance and hardness. Normal heat treatment on AISI 430 Ferritic Stainless Steel cannot be treated utilised to achieve this task. However, it can be treated through nitriding method. Nitrogen is well known to improve mechanical, wear and corrosion resistance of stainless steels. Normal heat treatment on AISI Ferritic Stainless Steel is not suitable to achieve this task. Thus, the aim of this work is to investigate the influence of nitriding on wear resistance properties of AISI 430 Ferritic Stainless Steel. The influence of nitriding on the steel were observed. Microstructures, hardness test and scratch resistance analysis for wear resistance were conducted and analysed. Nitriding was carried out at 1200°C for 1 h, 3 h and 5h using nitrogen gas as a medium. Martensitic transformation from ferrite was observed on the as-received samples. From microstructure observations, the influence of nitriding also could be seen. Martensite structure shows higher hardness compare to ferrite structure. Therefore, the hardness for 5 h nitrided sample is higher than 1 and 3 h nitrided sample as more martensite structures was formed at 5 h nitrided sample. Scratch resistance was conducted to analyse the influence of nitriding for wear resistance properties. The depth of penetration obtained shows how much improvement on tribology properties are made. Results from testing conducted shows that the improvement of wear resistance properties is dependent on nitriding time. The longer the nitriding time, the more nitrogen is diffused into the sample. As more nitrogen atoms diffused into the steel, improvement on wear resistance properties are higher.

Experimental studies carried out on the joining of grey lamellar graphite cast iron to low carbon steel by diffusion welding techniques had successfully produced a few diffusion couples, despite facing some earlier failures. Although faced with some success, analysis on the diffusion couples showed voids and incomplete bond/joint at the interface of the joints while the tensile strength value was found to be low. In furtherance, the diffusion couples were then subjected to a post-weld heat treatment (PWHT) that allowed for further diffusion process to take place to remove the voids and complete the bond/weld. The results revealed microvoids and interface lines at the interfaces of the specimens treated at temperatures of 800°C, and becoming less visible at 900°C. At an elevated temperature of 1000°C, on longer treatment times, apparently these microvoids and interface lines had disappeared, and the bond/weld at the interfaces of the diffusional welded couples seemed to be more complete. Thus, heat treatment time and temperature were found to have a strong influence on the structure, thickness and hardness of the diffusion layer produced.

Sialon and AISI 420 martensitic stainless steel were diffusion bonded in order to study the effect of bonding time on reaction layer’s growth. Joining of these materials was conducted at 1200°C under a uniaxial pressure of 17 MPa in a vacuum ranging from 5.0 to 8.0×10−6 Torr with bonding time varied for 0.5, 2, and 3 h. Thicker reaction layer was formed in longer bonded sample since the elements from sialon could diffuse further into the steel. Sialon retained its microstructure but it was affected at the initial contact with the steel to form the new interface layer. Diffusion layer grew toward the steel and it was segregated with the parent steel as a result of the difference in properties between these regions. The segregation formed a stream-like structure and its depth decreased when the bonding time was increased. The microstructure of the steel transformed into large grain size with precipitates. Prolonging the bonding time produced more precipitates in the steel and reduced the steel thickness as ...

This investigation proposed the low temperature thermochemical treatments in conventional tube furnace of hybrid treating which introduces nitrogen and carbon simultaneously with the aim to improve surface properties of AISI 316L. The outcome of the work showed the formation expanded austenite structured which is supersaturated with nitrogen and carbon. This structure is responsible to the higher hardness as well as better wear property without impairing its corrosion resistance. Characterization of this expanded austenite layers were performed including FESEM, USPM and elemental analysis to reveal the characters of the produced thin layers. Elemental profile of nitrogen and carbon across the hybrid treated layer were obtained by EDS-SEM. The results also demonstrate that hybrid treatment produces a thicker and unique layer on higher temperature treatments for 450°C without impairing its corrosion resistance according to the absence of nitride and carbide of treated layers.

An inner gear component, clutch-hub, was chosen as the object for a numerical study investigating the usefulness and effectiveness of employing numerical simulations in the design process of metal forming parts. A computer-aided design simulation tool CAMP form was employed in this study. Simulations for S10C steel using various die and workpiece geometries were carried out, and completeness of filling and load requirements were compared to determine the forming condition most suitable for production of the clutch-hub. The effect of shear friction factor on the forming process was examined using the most suitable die and workpiece geometries. Also, study on aluminum alloys Al1100-O, Al2024-T3, Al6061-T4 and Al7075-T4 with respect to their defect factors of work hypothesis, ( C 1 ) and Cockcroft and Latham ( C 2 ) were made in this paper. It was found that only Al6061-T4 could be considered as a substitute material of steel for cold forging of the clutch-hub.

High temperature gas nitriding performed on AISI 316L at the temperature of 1200°C. The microstructure of treated AISI 316L samples were observed to identify the formation of the microstructure of nitrided surface layer. The grain size of austenite tends to be enlarged when the nitriding time increases, but the austenite single phase structure is maintained even after the long-time solution nitriding. Using microhardness testing, the hardness values drop to the center of the samples. The increase in surface hardness is due to the high nitrogen concentration at or near the surface. At 245HV, the graph of the effective duration of nitriding process was plotted to achieve the maximum depth of nitrogen diffuse under the surface. Using Sigma Plot software best fit lines of the experimental result found and plotted to find out effective duration of nitriding equation as Y=1.9491(1-0.7947 x ), where Y is the thickness of nitrided layer below the surface and X is duration of nitriding process. Based on this equation, the duration of gas nitriding process can be estimated to produce desired thickness of nitrided layer.

In direct diffusion bonding of sialon to stainless steel, thermal residual stresses arise due to the difference in coefficient of thermal expansion of the two materials. These stresses frequently lead to failure of the bond. This behaviour is further influenced by the formation of interfacial reaction layers between ceramic and metal and the problem is essentially one of asymmetry of stresses in the interface between dissimilar materials. The present study demonstrates that a thin layer of austenitic stainless steel can be used as an interlayer to join two sialon components. In such a case the distribution of residual stresses is symmetrical across the composite join and provided that the thickness of the steel layer is less than a critical value, then fracture on cooling from joining temperature does not occur. The development of this process is described and a finite-element model has been used to predict the properties of the interfacial reaction layer between steel and ceramic which are consistent with the experimental observations.

Joining of ceramics to metal is not easy due to the difference in the thermal expansion of the two materials. In this research work, the joining of sialon to austenitic stainless steel and ferritic stainless steels were compared. At above a joining temperature of 1200°C, sialon will react with steel to form iron silicide and nitrogen is given off. Thus to counteract this effect, a high nitrogen content in the steel is one way of overcoming this problem by nitriding both austenitic and ferritic stainless steels at 1200°C. These materials were then joined to sialon using a hot press at 1250°C. The results show that inter-reaction and interdiffusion on both sides of the materials occur in the layer. Good interfaces were found between sialon and steels. Analyses on the joinings were carried out using a scanning electron microscope, an optical microscope, a hardness tester, and XRD. The analysis also indicated different morphology of the interfaces that were formed. A ductile interlayer was formed between the ferritic stainless steel and sialon, which enabled good joining. However, this layer is absent in the joining of austenitic stainless steel to sialon. In both cases of joining, the chemical reactions between the steels and sialons produce an intermediate hardness in the reaction layer. Thus the interfaces have the important role in reducing the effect of the thermal mismatch between the sialon and steel, where the formation of a composite interlayer provides properties that are intermediate between those of the steel and sialon. However, the joining of sialon to ferritic stainless steel is more successful compared to joining to austenitic stainless steel.

This paper investigates the low temperature thermochemical treatments in conventional tube furnace of hybrid treating which introduce nitrogen and carbon simultaneously with the aim to improve surface properties of austenitic AISI 316L and Duplex 2205 stainless steels. The expected resulting layer is a structure termed expanded austenite which is supersaturated with nitrogen and carbon and this structure are responsible to the higher hardness and better wear properties without impairing its corrosion resistance. Characterization of this expanded austenite layers have performed including Line scan elemental analysis, SEM and SPM were used to reveal the characters of the produced thin layers. Elemental profile of nitrogen and carbon across the hybrid treated layer were obtained by line scan mode EDS-SEM.

Fire retardant coating (FRC) is vital in construction building as its function is to insulate heat or fire from underlying substrate. The concern of a coating also focuses on the toxicity of the material to occupants during fire hazard. Thus, in this research, water-based acrylic was used as a binder with addition of vermiculite. This paper presents the effect of vermiculite on the improvement in fire resistant of the ammonium polyphosphate-pentaerythritol-melamine (APP-PER-MEL) coating which investigated using fire protection test and scanning electron microscopy (SEM). The detail compositions of acrylic media and vermiculite were analyzed by using X-ray fluorescence (XRF). The temperature-time curve and SEM image for formulations with vermiculite show the temperature is 150°C lower than formulations without vermiculite and better char structure is observed.

This study examined the microstructure and hardness of as-received and nitrided AISI 420 martensitic stainless steels. High temperature gas nitriding was employed to treat the steels at 1200 o C for one hour and four hours using nitrogen gas, followed by furnace cooled. Chromium nitride and iron nitride were formed and concentrated at the outmost surface area of the steels since this region contained the highest concentration of nitrogen. The grain size enlarged at the interior region of the nitrided steels due to nitriding at temperature above the recrystallization temperature of the steel and followed by slow cooling. The nitrided steels produced higher surface hardness compared to as-received steel due to the presence of nitrogen and the precipitation of nitrides. Harder steel was produced when nitriding at four hours compared to one hour since more nitrogen permeated into the steel.

This paper present mathematical model which developed to predict the nitrided layer thickness (case depth) of gas nitrided and plasma nitrided austenitic stainless steel according to Fick’s first law for pure iron by adapting and manipulating the Hosseini’s model to fit the diffusion mechanism where nitrided structure formed by nitrided AISI 316L austenitic stainless steel. The mathematical model later tested against various actual gas nitriding and plasma nitriding experimental results with varying nitriding temperature and nitriding duration to see whether the model managed to successfully predict the nitrided layer thickness. This model predicted the coexistence of ε-Fe2-3N and γ΄-Fe4N under the present nitriding process parameters. After the validation process, it is proven that the mathematical model managed to predict the nitrided layer growth of the gas nitrided and plasma nitrided of AISI 316L SS up to high degree of accuracy.

This paper presents the characterisation of hybrid treated layer on austenitic AISI 316L stainless steels using field emission scanning electron microscope (FESEM), universal scanning probe microscope (USPM) and nanoindentation after low temperature thermochemical treatments. By using these methods, the improvement of its mechanical properties due to the diffusion of carbon and nitrogen at low temperature treatments were confirmed. The hybrid treated layer has shown increment of hardness and elastic modulus compared to untreated sample. Based on the investigation, it is shown that all treated samples have enhanced E/H ratio which demonstrated the decreasing tendency to plastic deformation and reduced the disparity of properties, while keeping deformation within the elastic range.

In this work, the hybrid treated layer on austenitic AISI 316L stainless steels were characterized to investigate the improvement on its surface properties. Characterization of this resulting layer was performed by FESEM (Field Emission Scanning Electron Microscope), USPM (Universal Scanning Probe Microscope) and nanoindentation. By using these methods, changes in the mechanical properties due to the diffusion of carbon and nitrogen at low temperature treatments have been traced. This hybrid treated sample has confirmed a considerable increase in hardness and a small rise in the elastic modulus compared to the untreated sample. It is found that all treated samples have enhance E/H ratio which exhibited the decreasing tendency to plastic deformation and reduced the mismatch of properties, while keeping deformation within the elastic range.

Orthopaedic implants are mostly fabricated by Stainless Steel, Titanium, and Ni-Cr Alloys that consist of Chromium (Cr), Cobalt (Co), Nickel (Ni) and Molybdenum (Mo). 10-15% of population are affected by metals (Ni, Co, Cr, Mo) hypersensitivity reaction. Multilayer coating by Physical Vapour Deposition (PVD) has been applied onto orthopedic implants to prevent metallic ions leaching into human body. This paper aims to study the metal ions leaching of Cr, Ni, Mo, and Co from multilayer coatings of Chromium (Cr), Chromium Nitride (CrN), Chromium Carbonitride (CrCN) and Zirconium Nitride (ZrN) by Physical Vapour Deposition (PVD). Cr, CrN, CrCN and ZrN have been successfully deposited onto stainless steel substrates by CAPVD. XRD analysis detected major peak in preferred orientation of (200) and other peaks with (111), (220), (311) for CrN cubic phase. For CrCN, XRD analysis detected only low intensity peaks of Cr7C3 and ZrN peaks with preferred orientation of (111), (200) with other peak (220), (311) and (222). A seven days metal released test by ICP-MS showed that generally all ions concentration for Ni, Co, Mo decreased from uncoated substrate to multilayer coatings except for Cr. Metal released showed higher concentration for coatings deposition with longer deposition time at 10 minutes.