Materials Science Forum Vol. 979

Abstract: The quality of machining through process parameters on the responses in wire electrical discharge machining (WEDM) is studied. This paper discusses the optimization of parameters of a process in WEDM machining with the application of the desirability approach on the basis of response surface methodology (RSM). Pulse on time, servo speed rate, discharge current, and pulse off time have been considered as influential factors. The established experimental data of AA7075 aluminium reinforced with 9% of activated carbon composite to analyze the process parameter effects on responses, like material removal rate (MRR) and surface roughness (SR). After machining multiple regression analysis is used to find the interaction among the process parameters is obtained. The optimal parameters were found using the desirability optimization methodologies as 10.43mm³/min and 3.32μm respectively. The performance of the optimization test confirmed that the proposed method in this study effectively improves the performance of the WEDM process.

Abstract: Hybrid metal matrix composites (MMCs) were prepared with AA 5754 as matrix and B₄C (fixed with 1 wt.% and average particle size as 25 μm) and Al₂O₃ reinforcements (varied from 0.5 to 2 wt. % with the interval of 0.5 and average particle size as 50 nm) using Rheo-squeeze casting process. Microstructure images were taken to observe the uniform distribution of reinforcement particles on the matrix alloy. The tensile strength for AA 5754 with 1 wt.% B₄C and 2 wt.% Al₂O₃ hybrid composite showed higher value compared to base alloy and other composites. The wt. % of Al₂O₃ in the composite is increased to 2 %, the tensile strength and compressive strength were also increased due to combined Rheo-squeeze casting. AA 5754 reinforced with 1 wt.% B₄C and 1.5 wt.% Al₂O₃ MMC indicated the Impact strength value of 30 Joules which is higher than AA 5754 matrix alloy and other compositions.

Abstract: In recent years, aluminum alloys reinforced with nanosized ceramic particulates are finding wider applications in various engineering industries like automobile, aircraft, electronics and sports. The requirement of accurate machining of nanocomposite has also gets increased. In this research work, aluminum alloy 6061 reinforced with 1.5 Wt. % of nanoB₄C particulate was fabricated in cylindrical shape using ultrasonication assisted casting process. Medium duty lathe with poly crystalline diamond insert tool of 1600 grade was used to turn the Al/B₄C nanocomposites. During turning of Al/B₄C nanocomposites, cutting parameters like depth of cut, speed and feed were varied as per predefined level. Surface roughness of machined surface and power consumption during machining were measured using surface roughness tester and wattmeter respectively. ANOVA analysis was carried out and the optimum parameters for machining the nanocomposite were found out using MINITAB software. The nanocomposite machined with optimum parameters show good surface finish and consumed minimum power.

Abstract: In the present study Spark Plasma Sintering (SPS) technique is used to synthesis of particulate Ceramic Matrix Composites (CMCs). SPS is a type of hot pressing method and in this method, the rate of heating is from 100C to 1000C per minute with high densification. TiB₂ (average size of 14 μm) particles were chosen as matrix and SiC (average size of 1 μm) particles were used as reinforcement. In the first stage of the study, synthesis of CMCs with TiB₂ matrix and SiC reinforcement with varying volume% (0, 5, 10 and 15 vol.%) was carried out using Spark Plasma Sintering furnace available at IIT Madras in 1100°C, 40MPa and 10 min hold of time. But machining of CMCs from conventional machining processes is difficult especially to make complex and precise parts from CMCs. Hence, in the second stage of the work, Wire Electric Discharge Machining (WEDM) studies were carried out on the processed four composites by varying current (2, 3 and 4 A), Pulse on (Ton-30, 60 and 90 μs) and Pulse off time (Toff-5, 10 and 15 μs) as per Taguchi L₉ orthogonal array. WEDM studies revealed that at 4A current, 60μs Ton and 5μs Toff gave maximum material removal rate (MRR) of 2.93 mm³/s, 2.27 mm³/s, 2.71 mm³/s and 0.62 mm³/s for CMC with 0% SiC, 5% SiC, 10% SiC, 15% SiC vol.% reinforcement respectively. To reduce material wastage during machining, kerf width is considered and in which 3A current, 90μs Ton and 5μs Toff gave the least kerf of 0.35 mm, 0.32 mm, 0.33 mm and 0.28 mm for 0% SiC, 5% SiC, 10% SiC, 15% SiC vol.% reinforcement respectively.

Abstract: In this work, aluminum (Al) alloy reinforced with boron carbide (B₄C) nanoparticles were fabricated using ultrasonic assisted casting process. To investigate the effect of ultrasonic power on processing the metal matrix nanocomposites (MMNCs), the MMNC samples were processed with 1.0 kW, 1.5 kW and 2.0 kW of ultrasonic power. The results indicate that the ultrasonic power play a significant role in dispersing the B₄C nanoparticles uniformly in Al melt and it also affects the mechanical properties of the fabricated MMNCs. From microstructural analysis it was observed that the MMNC sample processed with 2.0 kW ultrasonic powers possessed the good dispersion of B₄C in the Al melt which is the prime criteria for the good mechanical properties.

Abstract: The epidemic adoption of particulate metal matrix composites (MMCs) for engineering applications has been delay by the high cost of producing components of even minimally complex shape. The aluminum-based composites find its applications widely in transport, aerospace, marine, automobile and mineral processing industries, owing to their improved strength, stiffness and wear resistance properties. This paper, presents the overview of the addition of different reinforcements to aluminium alloy. The reinforcements are added to the Al7075 by using stir casting method. Effect of these reinforcements like Titanium carbide (TiC) and silicon (Si) influencing on the mechanical properties like tensile strength, hardness was studied. Research relevant to these factors which influence particles distribution were noticed by conducting the experimental studies of Al7075 hybrid composites.The mechanical properties and the microstructure of Al–TiC-Si metal matrix composite has shown the significant improvement in Hardness and Tensile strength, with increase in TiC and Si particles in weight percentage of composites.

Abstract: Titanium Boride (TiB₂) particles reinforced with aluminum alloy (AA 7075) composites were developed using the two-step stir casting method. TiB₂ with aluminium alloy was varied in 5, 10, 15 weight percentages (wt.%) . The mechanical properties of the composites were assessed through density, hardness, tensile and impact. Factography observations were also evaluated with Scanning Electron Microscopy (SEM) and phase identification of the composite was carried out through X-ray diffraction technique (XRD). The XRD pattern of alloy and composites revealed peaks of Al and TiB₂ particles and the intensity of TiB₂ particles increased with increase in wt. %. Compared to the base matrix, the density and hardness of composites increased with the wt. % of TiB₂. Addition of TiB₂ particles exhibited grain refinement, thereby improving the mechanical properties. Composite materials exhibited high load bearing capacity due to the strong bonding of TiB₂ and matrix material resulting in increased impact energy. The tensile strength of the composite increased with increasing wt. % of reinforcement. The failure in the composites observed were dimpled structure and ridges, voids, and cracks.

Abstract: Hybrid metal matrix composites new generation of engineering materials with better mechanical and tribological properties. Al6063 alloy has the matrix material and reinforcement SiC and ZrO₂ micro particles are selected for the study. In this work, Al6063/ SiC/ZrO₂ hybrid composite fabricated with different wt. % of reinforcements (0.5, 1, and 1.5 wt. % SiC and 1 wt. % ZrO₂ constant for all composites) by using stir casting process. The thixoforming process applied to casted composite. The SiC and ZrO₂ particle was distributed in the Al-matrix are visible in the SEM micrographs .The hardness value of the composite 34.75% increased due to the addition of constant 1 wt. % of ZrO₂ and varying SiC reinforcement particles. The charpy impact strength of Al composite was increased by 23.52 % with the addition of the constant 1 % wt. ZrO₂ and 1 wt. % SiC particles. Wear behavior of Al6063/SiC/ZrO2 hybrid composite was tested using pin-on-disc machine. The wear volume loss decreased for 1.5 % wt. SiC and 1 wt. % ZrO2 compared to other composite. The worn surface morphology has revealed that Al6063 base alloy with deep groove. The composite with 0.5%, 1% wt. SiC and constant 1 wt.% ZrO₂ showed more debris, dilamation and cleavage particles formed on the pin surface. The composite with 1.5 % wt. SiC and constant 1 wt.% ZrO₂ showed less wear loss and smooth surface formation.

Abstract: The Aluminum alloys and its composites are used in the aerospace, automobile and marine industries due to their higher strength, stiffness and wear resistance properties. This study is focused on mechanical and tribological study of Al 7075 hybrid composite reinforced with B₄C, Gr and Fly ash. The reinforcements are added to Al alloy in three different compositions such as (4wt% B₄C/4wt% Gr/7wt% Fly ash, 4wt% B₄C/5wt% Gr/8wt% Fly ash and 4wt% B₄C/6wt% Gr/9wt% Fly ash). The stir casting machine was used for manufacturing hybrid composites. Hardness and wear tests were conducted for three different Al 7075 hybrid composites. The microstructure showed that the reinforcement was uniformly distributed in the matrix without agglomeration. The hardness and wear test results revealed that the composite with 4wt% B₄C /6wt% Gr/9wt% Fly ash exhibited an increase in hardness value of about 22.69% and the minimum wear rate as compared to other composites.