M. Adam Khan

Machinability of Nickel-Based Superalloy by Abrasive Water Jet Machining

This paper deals with the machinability of nickel-based superalloys using abrasive water jet machining process. The machining studies were carried out with three different parameters such as water jet pressure, traverse speed of jet nozzle, and standoff distance at three different levels. The performances of the process parameters are evaluated by measuring difference in kerf width, kerf wall inclination, and material removal rate (MRR). Further, the surface morphology and material removal mechanisms are analyzed through scanning electron microscope (SEM) images. It is found that water jet pressure is the most influencing factor related to surface morphology and surface quality.

Machinablity of Hybrid Natural Fiber Composite with and without Filler as Reinforcement

The filler materials are reinforced along with natural fibers in the composite to improve the quality and property of the component materials based on the requirements and its applications. In this paper, hybrid natural fiber composites were developed with and without filler materials as reinforcement. The developed hybrid natural fiber composites are machined using abrasive water jet cutting process with three different cutting parameters. The influences of cutting parameters are evaluated with respect to the kerf wall inclination, material removal rate, and surface roughness. The surface morphology was also studied to infer the basic mechanism involved during composite machining. The hybrid fiber composite with filler has proved that it can produce good engineering component without delamination and fiber pullouts during machining.

Oxidation and Hot Corrosion Behavior of Nickel-Based Superalloy for Gas Turbine Applications

This paper investigates the cyclic oxidation and hot corrosion behavior of Inconel 617 at elevated temperatures. The substantial role of alloying elements with respect to oxidation and hot corrosion were analyzed with respect to corrosion kinetics, surface morphology and X-ray analysis of the oxide scales formed. The cumulative mass change shows that the presence of V2O5 in salt mixture plays predominant role in corrosion attack. Consistency of oxide scale, rich in Cr2O3, NiO, Al2O3 and NiCr2O4 was confirmed through X-ray analysis. Inconel 617 has good oxidation resistance and prone to corrosion attack at elevated temperatures due to the presence of vanadium in salt mixture which accelerates hot corrosion.

MACHINING PARAMETERS OPTIMIZATION FOR ALUMINA BASED CERAMIC CUTTING TOOLS USING GENETIC ALGORITHM

Alumina-based ceramic cutting tools can be operated at higher cutting speeds than carbide and cermet tools. This results in increased metal removal rates and productivity. While the initial cost of alumina based ceramic inserts is generally higher than carbide or cermet inserts, the cost per part machined is often lower. Production cost is the main concern of the industry and it has to be optimised to fully utilize the advantages of ceramic cutting tools. In this study, optimization of machining parameters on machining S.G. iron (ASTM A536 60-40-18) using alumina based ceramic cutting tools is presented. Before doing the optimization work, experimental machining study is carried out using Ti [C,N] mixed alumina ceramic cutting tool (CC 650) and Zirconia toughened alumina ceramic cutting tool (Widialox G) to get actual input values to the optimization problem, so that the optimized results will be realistic. The optimum machining parameters are found out using Genetic algorithm and it is found that Widialox G tool is able to machine at lower unit production cost than CC 650 tool. The various costs affecting the unit production cost are also discussed.

Influence of plasma coatings on Inconel 617 for gas turbine applications

Abstract The Inconel 617 with plasma sprayed Al2O3–40%TiO2 (A40T) and NiCr–Cr2O3 coatings were investigated for the hot corrosion behaviour at 1000°C for gas turbine applications. The behaviour of the alloy under the mixed salt environment with and without V2O5 in Na2SO4 and NaCl was analysed by means of mass change per unit area, optical and SEM images along with X-ray diffraction and EDAX. Microstructural and EDAX analyses revealed presence of oxides, rich in Ni and Mo on the surface of the samples. The coated sample exhibited better corrosion resistance in A40T and NiCr – Cr2O3 coatings than bare alloy.

Sliding wear behaviour of plasma sprayed coatings on nickel based superalloy

In this paper, the sliding wear behaviour of nickel based superalloy pin was investigated on disc with two different coatings. The plasma sprayed NiCr–Cr2O3 coating and Al2O3+40%TiO2 (A40T) coating were used on the disc for wear studies. The sliding wear tests were performed on dry conditions at room temperature for a constant sliding velocity for two different applied loads (5 and 10 N). The mass loss, wear resistance and coefficient of friction between the pin and disc were studied during investigations. The wear mechanism involved in the NiCr–Cr2O3 coatings is three-body abrasion and Cr2O3 being the third body between pin and disc. The wear rate is high due to the applied load and suppressed cracks. In A40T coating, the minute debris collected on the surface of the coatings acts as a solid lubricant and reduces friction and wear rate. The SEM and energy dispersive spectroscopy analysis were also carried out for characterisation studies on pin after wear studies. The life of nickel pin on A40T coatings is found superior than the NiCr–Cr2O3 coated disc.

Some experimental investigations on drilling AA (6351)-SiC-B4C composite

ABSTRACT This study is performed to assess the drilling of silicon carbide (SiC) and boron carbide (B4C) particles reinforced with 6351 aluminum matrix. Stir cast specimens were prepared using an electrical resistance furnace, and the mechanical properties were revealed. Experiments were carried out with varying spindle speed, feed rate, and point angle to analyze the drill tool temperature, thrust force, and surface roughness. Analysis of variance (ANOVA) was performed to determine the significance and the percent of influence of each input process parameter on the quality response. The results show that the increasing spindle speed reduces the thrust force and surface roughness, but increases the tool temperature. Furthermore, the point angle tool of 90° reduced the thrust force significantly but negatively influenced the other output responses. The spindle speed contributes more to the thrust force and surface roughness by 63.53% and 44.01%, respectively, and the point angle contributes 48.88% to the tool temperature.

Laser-treated austenitic steel and nickel alloy for human implants

ABSTRACT The recent research in biocompatible materials has been useful in replacing and supporting the fractured natural human bones/joints. Under some condition, negative reaction like release of ions from the bare metal toward the human body fluid leads to corrosion. In this proposed research paper, the biocompatibility of the laser surface-modified austenitic stainless steel (SS316L) and nickel-based superalloy (Inconel 718) was studied. The investigation on laser-modified surfaces is evaluated through electrochemical polarization analysis using simulated body fluid (SBF). The samples subjected to electrochemical polarization analysis were characterized by optical image analysis, SEM, EDS, and XRD analysis. It was inferred that laser surface-modified materials provided enhanced corrosion resistance and bare nickel alloy is more susceptible to corrosion by SBF.

Effect of Tool Wear on Machining GFRP and AISI D2 Steel Using Alumina Based Ceramic Cutting Tools

The alumina based ceramic cutting tools are used to machine glass fibre reinforced plastic (GFRP) composite material and AISI D2 steel. The machining studies were conducted using Ti[C,N] mixed alumina based ceramic cutting tool (CC650) and SiC whisker reinforced alumina based ceramic cutting tool (CC670). Machining process was performed at different cutting speeds at constant feed rate and depth of cut and the flank wear of the cutting tools were measured. From the machining studies, the wear behaviour of the cutting tool are studied and compared with reference to the work material. Very smooth wear land was observed while machining GFRP composite whereas, ridges and groves were observed while machining steel using alumina based ceramic cutting tools. The hard metal chips produced during machining has induced to undergo the severe in changes on machining D2 steel. Based on the flank wear, tool face fibre / matrix chip has prone to maximum wear of 0.4mm compared to machining a metal. On machining AISI D2 steel the machining has reduced one fold (1:2) than the GFRP composite material. In summary, Ti[C,N] mixed alumina cutting tool performance better on machining AISI D2 steel and SiC whisker reinforced alumina cutting tool for machining GFRP composite.

Hot corrosion behaviour of nickel–iron-based superalloy in gas turbine application

ABSTRACT Nickel-based superalloys are mostly used as gas turbine components. During combustion, the sodium sulphate and sodium chlorides with vanadium pentoxide are dominating corrosive species in gas turbine environment. The eutectic point of the salt deposits varies with respect to combustion/operating temperature and corrosion kinetics are initiated. In this research, hastelloy X was chosen as a candidate material in a simulated oxidation and gas turbine hot corrosion at 1100°C. The mass change per unit area is gradual in mixed salt environment and catastrophic under atmospheric air for oxidation studies. This observation may be due to the oxide scale formation and spalling of the same on prolonged exposure. The exposed samples were subject to SEM, EDS and XRD analysis. The samples exposed to molten salt have undergone different surface morphology during the incubation period. The features of the candidate material are discussed in detail.