Pardeep Sharma

Production and some properties of Si3N4 reinforced aluminium alloy composites

Abstract The present research work focuses on the production of aluminium (AA6082-T6) matrix composites reinforced with various weight percentage of silicon nitride particles by conventional stir casting route. The percentage of reinforcement is varied from 0 wt.% to 12 wt.% in a stage of 3%. The microstructures and mechanical properties of the fabricated aluminium matrix composites are investigated. The scanning electron microstructure images reveal the presence of Si3N4 particles in the aluminium matrix. The distribution of Si3N4 particles has also been recognized with X-ray diffraction technique. The mechanical properties such as ultimate tensile strength and hardness have improved at the cost of reduction in ductility with increase in weight percentage of silicon nitride particulates in the aluminium metal matrix. The density and porosity of the composites also show an increasing trend with increase in volume fraction of Si3N4 particles in the aluminium matrix.

A study on microstructure of aluminium matrix composites

Abstract This work focuses on the effect of graphite particles addition on the microstructure of Al6082 metal matrix composites manufactured by conventional stir casting process. The reinforcement content was varied from 0% to 12% in a step of 3%. The microstructures of the manufactured composites were analyzed by scanning electron micrographic test. Elemental mapping of the Al6082 + 12% Gr reinforced composite was carried out to see the different elements present with their amount. Different elements present in the manufactured composites were verified by X-ray diffraction technique to justify the elemental map analysis. The result of this microstructural investigation revealed that a non-uniform distribution of graphite particles takes place at all weight percentages of graphite reinforcement.

Tribological and mechanical behavior of particulate aluminum matrix composites

Aluminum and its alloy are light in weight, ductile, strong and long lasting, having high corrosion resistance, good conductor of heat and electricity and are 100% recyclable. Despite all these good qualities, it has low wear resistance. But some applications entail high hardness and tensile strength, high modulus of elasticity than the conventional aluminum alloy with good tribological properties. Keeping in view the enhancement of mechanical as well as tribological properties with reduction in weight, the aluminum alloy is reinforced with a second phase which is hard and brittle, and the newly formed material has better mechanical and tribological properties. The paper reviews the various manufacturing processes of aluminum matrix composites, and it was found that the mechanical and tribological properties of the single reinforcement composites are better as compared to pure aluminum and its alloys irrespective of the aluminum matrix composites manufacturing process. Further, it was found that most of the hybrid composites exhibit better mechanical and tribological properties as compared to single reinforcement composites.

On the Use of Ball Milling for the Production of Ceramic Powders

In the present research work, the mixture of boron carbide and graphite ceramic powders with a theoretical composition of 50% each by weight were mechanically alloyed in a laboratory ball mill with different milling times of 12.5, 25, 50, 75, and 100 h. The investigation was carried out on the morphologies and densities of ball-milled powders. Morphology results revealed that ball milling is a very dominant and dynamic practice for preparation of two different powders into single entity powder having appropriate and consistent morphology. The results of density measurement showed that with milling times, density increased initially and then reduced with further increase in milling times. The density is reduced by 1.68% as the milling time increased from 0 to 100 h.

Effect of graphite reinforcement on physical and mechanical properties of aluminum metal matrix composites

ABSTRACT This work focuses on the effect of graphite particle addition on the properties of AA6082 metal matrix composites fabricated by conventional stir casting method. The percentage of reinforcement was varied from 0% to 12% in a step of 3%. The results revealed that with the addition of graphite particles, the micro- and macro-hardness decreased by 11.11% and 10.44%, respectively. The ultimate tensile strength also decreased by 5.88% with a reduction in percentage elongation from 8.7 to 6.8. The density decreased by 4.1% with an increase in porosity from 0.37% to 2.27% as the weight percentage of graphite particles increased from 0% to 12%.

Production and characterization of AA6082-(Si3N4 + Gr) stir cast hybrid composites

ABSTRACT The present research work emphasizes the development of hybrid aluminum (AA6082) matrix composites (HAMCs) reinforced with different weight percentages (wt.%) of ball-milled (silicon nitride (Si3N4) + graphite (Gr)) ceramic particulates by conventional stir casting process. Si3N4 and Gr are ball milled to obtain a definite density of combined powder. The weight percentage of ball-milled ceramic powder is varied from 0 to 12 wt.% in a stage of 3%. The microstructures as well as mechanical properties of the fabricated hybrid composites are analyzed. The scanning electron micrograph reveals the uniform distribution of ball-milled (Si3N4 + Gr) ceramic particulates in the aluminum matrix. The distribution of ball-milled (Si3N4 + Gr) ceramic particulates has also been analyzed with x-ray diffraction (XRD) technique. Both the hardness and ultimate tensile strength have enhanced with a reduction in percentage elongation with increase in weight percentage of ball-milled (Si3N4 + Gr) ceramic particulates in the aluminum matrix.

A study on wear behaviour of Al/6101/graphite composites

Abstract The current research work scrutinizes aluminium alloy 6101-graphite composites for their mechanical and tribological behaviour in dry sliding environments. The orthodox liquid casting technique had been used for the manufacturing of composite materials and imperilled to T6 heat treatment. The content of reinforcement particles was taken as 0, 4, 8, 12 and 16 wt.% of graphite to ascertain it is prospective as self-lubricating reinforcement in sliding wear environments. Hardness, tensile strength and flexural strength of cast Al6101 metal matrix and manufactured composites were evaluated. Hardness, tensile strength and flexural strength decreases with increasing volume fraction of graphite reinforcement as compared to cast Al6101 metal matrix. Wear tests were performed on pin on disc apparatus to assess the tribological behaviour of composites and to determine the optimum volume fraction of graphite for its minimum wear rate. Wear rate reduces with increase in graphite volume fraction and minimum wear rate was attained at 4 wt.% graphite. The wear was found to decrease with increase in sliding distance. The average co-efficient of friction also reduces with graphite addition and its minimum value was found to be at 4 wt.% graphite. The worn surfaces of wear specimens were studied through scanning electron microscopy. The occurrence of 4 wt.% of graphite reinforcement in the composites can reveal loftier wear possessions as compared to cast Al6101 metal matrix.

Metallurgical and Mechanical Characterization of Al 6082-B4C/Si3N4 Hybrid Composite Manufactured by Combined Ball Milling and Stir Casting

Aluminium matrix composites (AMCs) having more than one reinforcement (hybrid AMCs) found enlarged use due to better strength, high thermal stability and wear resistance properties and can be a substitute for single reinforced AMCs .The effect of varying ball milled (BM) B4C/Si3N4 particles on the microstructure of as cast AA6082 and mechanical properties of AA6082 alloy hybrid composites produced by combined ball milling and conventional stir casting method have been reported. The combined reinforcement of BM B4C/Si3N4 particles were varied from 0-9 % in a step of 3. The wettability of B4C/Si3N4 into the aluminium melt has been increased by ball milling the boron carbide with silicon nitride powder, so that combined reinforcement of B4C/Si3N4 neither float nor sink in the aluminium melt. The investigated result showed that addition of combined reinforcement of BM B4C/Si3N4 increased Hardness and Ultimate tensile strength at the cost of reduction in percentage elongation.

Influence of Silicon Carbide/Graphite addition on properties of AA6082 reinforced composites

ABSTRACT AA6082 matrix hybrid composites reinforced with different weight percentages (wt. %) of (SiC + Gr) ceramic particulates by conventional stir casting process is manufactured. The weight percentage of ceramic powder is varied from 4 wt. % to 12 wt. % in a stage of 4 wt. %. The microstructures, physical properties such as density and porosity, as well as mechanical properties like hardness and tensile strength of the fabricated hybrid composites, are analysed. The optical micrographs reveal the uniform distribution of (SiC + Gr) ceramic particulates in the aluminium matrix. Density and porosity of hybrid composite increases from 2.69 to 2.75 g/cm3 and 0.37% to 1.23% with increase in weight percentage of (SiC + Gr) ceramic particulates in the aluminium matrix from 0 wt. % to 12 wt. % respectively. Both the hardness and ultimate tensile strength have enhanced from 52 to 84 VHN and 163 to 189 MPa, respectively, with a reduction in percentage elongation from 8.6 to 5.2 with rise in weight percentage of (SiC + Gr) ceramic particulates in the aluminium matrix from 0 wt. % to 12 wt. %, respectively.