S.A. Kori

Influence of particle size on Cutting Forces and Surface Roughness in Machining of B4Cp - 6061 Aluminium Matrix Composites

Amongst advanced materials, metal matrix composites (MMC) are gaining importance as materials for structural applications in particular, particulate reinforced aluminium MMCs have received considerable attention due to their superior properties such as high strength to weight ratio, excellent low-temperature performance, high wear resistance, high thermal conductivity. The present study aims at studying and comparing the machinability aspects of B4Cp reinforced 6061Al alloy metal matrix composites reinforced with 37μm and 88μm particulates produced by stir casting method. The micro structural characterization of the prepared composites is done using Scanning Electron Microscopy equipped with EDX analysis (Hitachi Su-1500 model) to identify morphology and distribution of B4C particles in the 6061Al matrix. The specimens are turned on a conventional lathe machine using a Polly crystalline Diamond (PCD) tool to study the effect of particle size on the cutting forces and the surface roughness under varying machinability parameters viz., Cutting speed (29-45 m/min.), Feed rate (0.11-0.33 mm/rev.) and depth of cut (0.5-1mm). Results of micro structural characterization revealed fairly uniform distribution of B4C particles (in both cases i.e., 37μm and 88μm) in 6061Al matrix. The surface roughness of the composite is influenced by cutting speed. The feed rate and depth of cut have a negative influence on surface roughness. The cutting forces decreased with increase in cutting speed whereas cutting forces increased with increase in feed and depth of cut. Higher cutting forces are noticed while machining Al6061 base alloy compared to reinforced composites. Surface finish is high during turning of the 6061Al base alloy and surface roughness is high with 88μm size particle reinforced composites. As the particle size increases Surface roughness also increases.

Dry Sliding Wear Behavior of Graphite Particulate Reinforced Al6061 Alloy Composite Materials

This present paper is an investigation made to study the un-lubricated sliding wear behavior of Al6061 alloy composites reinforced with graphite particulates of size 100-125 μm. The content of graphite in the alloy was varied from 6-9% in steps of 3 wt. %. The liquid metallurgy technique was used to fabricate the composites. A pin-on-disc wear testing machine was used to evaluate the volumetric wear loss, in which a hardened EN32 steel disc was used as the counter face. The results indicated that the volumetric wear loss of the composites was lesser than that of the Al6061 matrix alloy and it further decreased with the increase in graphite content up-to 6 wt.%. For composites containing 9 wt. % of graphite particulates, the volumetric wear loss was more than that of 6wt. % composites, but lesser than base matrix alloy. However, the material loss in terms of wear volume increased with the increase in load and sliding speed, both in case of composites and the alloy.

Microstructure and Mechanical Properties of Al6061-Graphite Composites Fabricated by Stir-Casting Process

In the present study, the experimental results of the mechanical properties of Al6061-Graphite composites presented. The composites containing 6 to 9 wt% of graphite in steps of 3 wt% were prepared using liquid metallurgy route in particular stir casting technique. For each composite, reinforcement particles were preheated to a temperature of 250°C and then dispersed in steps of two into the vortex of molten Al6061 alloy to improve the wettability and distribution. Microstructural characterization was investigated by optical and scanning electron microscopy. Tensile and hardness tests were carried out in order to identify mechanical properties of composites. The results of microstructural study revealed uniform distribution of graphite particles and low porosity in micro composite specimens.The results of this study revealed that as graphite percentage was increased, there was significant increase in ultimate tensile strength, yield strength and ductility, accompanied by a nominal drop in the hardness of the material

Effect of SiC and Graphite Particulates Addition on Wear Behaviour of Al2219 Alloy Hybrid Composites

In this investigation wear behaviour of A12219 alloy reinforced with SiC and graphite particulates were studied. The percentage of silicon carbide and graphite as reinforcements were varied from 2 wt.% to 4 wt.% in steps of 2. Energy dispersive spectroscopy and scanning electron microphotographs were used to confirm the presence of SiC and graphite particulates and its uniform distribution over the aluminum matrix. Wear behaviour of aluminum alloy Al2219 reinforced with silicon carbide and graphite fabricated by stir casting process was investigated. The wear properties of the metal matrix composites were studied by performing dry sliding wear test using a pin-on-disc wear tester. The experiments were conducted at a constant sliding velocity of 1.73m/s over a load of 2kg. The results showed that the wear resistance of Al2219-2%SiC-2% graphite and Al2219-4%SiC-4% graphite composites were better than the unreinforced alloy. The wear in terms of weight loss and wear rate was found to decrease with the increasing the weigh percentages of SiC and graphite. To study the dominant sliding wear mechanism worn surfaces were analyzed using scanning electron microscopy.

Microstructure and Mechanical Characterization of Al-Tib2 In Situ Metal Matrix Composites Produced via Master Alloy Route

In the present work, Al-TiB2 in-situ metal matrix composites were processed via master alloy route at 800°C-30 min. with 5 and 7wt% of TiB2 particles. Microstructural characterization of the prepared insitu composites were carried out using XRD, SEM/EDX studies. X ray diffraction studies have shown the presence of Al3Ti and TiB2 phases, however, the presence of AlB2 particles is also highly likely. SEM/EDX characterization revealed fairly uniformly distributed TiB2 particles having hexagonal morphology with size distribution in the ranges between 0.5-10μm. Further, presence of TiB2 particles in Al matrix have resulted in improvement in hardness and tensile properties of the Al matrix while decrease in ductility was observed.

Dry Sliding Wear Performance of A356 Alloy with Minor Additions of Magnesium

In the present investigation, effect of minor additions of magnesium (Mg) content on the dry sliding wear behavior of A356 alloy has been reported. Alloy composition, normal pressures and sliding distances on A356 alloy has been studied. The worn surfaces were characterized by SEM microanalysis. The results indicate that, the wear rate of A356 alloy increases with increase in normal pressures and sliding distances in all the cases and decreases with 0.7% Mg addition to the A356 alloy. This is due to the change in microstructure resulting in improvement of hardness and strength of the alloy. The worn surface study indicates that, the formation of oxide layer between the mating surfaces during sliding improves sliding wear performance.

Processing and Microstructural Characterization of Cermet-Reinforced Aluminium Matrix Composite by Solidification Process

The present work deals with the preparation of the aluminium matrix composite using a ceramic and metallic combination as reinforcements and using liquid metallurgy route of solidification process. The desired properties of composites have been influenced by the solidification behaviour of the cast metal matrix composites, which has been imposed to study the solidification behaviour of metal matrix at different weight fraction of reinforcement particulates. Al7075 was used as matrix and tungsten carbide, and cobalt particulates were used as reinforcements. During the preparation, an addition of magnesium was used to increase the wettability of the particulates during the mixing. XRD/EDX/SEM characterizations of the prepared composites were conducted, where a fairly uniform distribution of the reinforced particulates was found over the matrix.

Studies on 3 and 9 wt. % of B4C particulates reinforced Al7025 alloy composites

In the present investigation sysnthesis, microstructure study and tensile behavior of 3 and 9 weight percentage of B4C particulate reinforced Al7025 alloy composites has been reported. Al7025 matrix composite containing boron carbide were fabricated by conventional liquid stir casting method. The composites containing 3 and 9 wt. % of B4C particulates were fabricated for the study. The microstructure of the composites were examined by scanning electron microscopy. Further, tensile behavior of as cast Al7025 alloy, Al7025-3 wt. % B4C and 9 wt. % B4C composites were studied. Tensile properties like ultimate tensile strength, yield strength and percentage elongation were evaluated as per ASTM standards. Microstructural observation revealed the uniform distribution of particles in the Al7025 alloy matrix. From the analysis, it was found that the ultimate tensile strength and yield strength of composites were increased due to increasing amount of boron carbide particle in the Al7025 alloy matrix. Percentage elongation of the composite decreases with increasing order of B4C particulates in soft Al alloy.In the present investigation sysnthesis, microstructure study and tensile behavior of 3 and 9 weight percentage of B4C particulate reinforced Al7025 alloy composites has been reported. Al7025 matrix composite containing boron carbide were fabricated by conventional liquid stir casting method. The composites containing 3 and 9 wt. % of B4C particulates were fabricated for the study. The microstructure of the composites were examined by scanning electron microscopy. Further, tensile behavior of as cast Al7025 alloy, Al7025-3 wt. % B4C and 9 wt. % B4C composites were studied. Tensile properties like ultimate tensile strength, yield strength and percentage elongation were evaluated as per ASTM standards. Microstructural observation revealed the uniform distribution of particles in the Al7025 alloy matrix. From the analysis, it was found that the ultimate tensile strength and yield strength of composites were increased due to increasing amount of boron carbide particle in the Al7025 alloy matrix. Percentage el...

Preparation and Characterization of Al-1Ti-3B Master Alloys by Salt Route and Evaluation of their Grain Refining Performance on Al-7Si Alloys

In the present work, ternary Al-1Ti-3B master alloys were prepared in an induction furnace via salt route which involves reaction between preheated halide salts (K2TiF6 and KBF4) and liquid molten Al. During preparation process parameters such as reaction temperatures of 800, 900, 1000°C and reaction times 45, 60, 75 min. have been used to study the influence of these parameters on the morphology of particles present in the master alloy and inturn on the grain refining efficiency of Al-7Si alloy. The indigenously prepared master alloys were characterized by chemical analysis; particles size analysis, XRD and SEM/EDX microanalysis. Results of particle size analysis suggest that the sizes of the particles present in Al-1Ti-3B master alloys increases with increase in reaction temperature (800-1000°C) and reaction time (45-75 min.). However, the population of the particles having sizes less than 10µm decreases with increase in reaction time and temperature. Further, SEM/EDX studies revealed different morphologies of the particles present in the master alloy when processed at different reaction temperatures and reaction times. Further, the performances of the above-prepared master alloys were assessed for their grain refining efficiency on Al-7Si alloy by DAS analysis and by CACCA studies. Results of grain refinement studies and CACCA studies suggest that, Al-1Ti-3B master alloy prepared at reaction temperature of 800°C with a reaction time of 60min. shows better grain refining performance on Al-7Si alloy when compared to the same master alloy prepared under different processing conditions.