K. Rajkumar

Electrolytic concentration effect on the abrasive assisted-electrochemical machining of an aluminum–boron carbide composite

ABSTRACT All engineering materials can be machined by one or combination of processes in such a way that the material’s potential is fully exploited. Electrochemical machining is found to be a most promising process that produces various components from the hard-to-machine materials for the various applications. Electrolyte concentration is playing a positive role by improving the electrolyte conductivity, but negatively forming the passivation layer on the cut surfaces. In order to improve the surface finish and removal of generated residual materials from the cut surfaces, abrasive particles were fed along with electrolyte into the machining zone. This present paper investigates the sodium chloride (NaCl) electrolyte with varied concentration (10–30%) in association with SiC abrasive particles on the material removal rate, surface roughness, and radial overcut while machining of aluminum 6061–boron carbide (5–15 wt%) composites. This study conclusively derived that electrolyte concentration up to 20% exhibited a positive role in the material removal rate for the machining of composites because the rate of dissolution was of higher magnitude. Externally supplied abrasive particles along with electrolyte reduced the surface roughness and radial over cut to an extent. Conversely, at higher electrolyte concentration, the externally supplied abrasive particles have a little effect on the removal of the formed passivation layer as confirmed by SEM analysis.

Influence of Graphite Reinforcement on Mechanical Properties of Aluminum-Boron Carbide Composites

This paper deals with the mechanical properties in conventional heat treatment of Al (6061)-B4C-Graphite. Aluminium Metal Matrix Composites (MMC) is fabricated through two step stir casting method. The composites were fabricated with various volume percentage levels as Aluminium reinforced with (5, 10 &15%) Boron Carbide and (5,10 & 15%) of Graphite. Fabricated composites were subjected to conventional heat treatment for enhancing the mechanical properties. Influences of Graphite reinforcement on mechanical properties of Aluminum-Boron carbide composites were analyzed. The microstructure studies were also carried out. It is observed that increasing the graphite content within the aluminum matrix results in significant decrease in ductility, hardness, ultimate tensile strength. The addition of boron carbide conversely increased the hardness of the composites.

Abrasive Assisted Electro Chemical Machining of Aluminum-Boron Carbide-Graphite Hybrid Composite

In this paper, attempts have been made to model and optimize process parameters in Abrasive assisted Electro-Chemical Machining (AECM) of Aluminium-Boron carbide-Graphite composite using cylindrical copper tool electrodes with SiC abrasive medium. Optimization of process parameters is based on the statistical techniques with four independent input parameters such as voltage, current, reinforcement and feed rate were used to assess the AECM process performance in terms of material removal rate. The obtained results are compared with without abrasive assisted electro chemical machining of Aluminium-Boron carbide-Graphite composite. Abrasive assisted ECM process exhibited higher material removal rate from composite material when compared with without abrasive assisted ECM.

Effect of Boron Carbide and Graphite on Machining Characteristics of Aluminium Boron Carbide Composite

This paper presents the mechanical and machinability properties of aluminium 6061 alloy reinforced with boron carbide composite is compared with the addition of graphite particles with AlB4C. The composites were fabricated by stir casting process. The experimental results showed that the hardness of the composite increases with the increasing addition of boron carbide. Tests for machinability characteristics was carried out with carbide tool at different cutting speeds keeping feed and depth of cut as constant. The machining tests revealed that the addition of graphite to Al-B4C composite has enhanced its machining properties.

Mechanical Properties of Almond Shell-Sugarcane Leaves Hybrid Epoxy Polymer Composite

In this work agricultural wastages such as sugarcane leaves and almond shell particles were reused as reinforcement in polymer material. This paper revealed the effect of sugarcane leaves, and almond shell particle on mechanical property of polymer composites. Sugarcane leaves were chopped to size of 50mm*50mm and almond shell of average 1mm particle size were used to fabricate epoxy polymer composite by hand layup technique. Tensile, flexural and impact test were carried out to evaluate the mechanical property of the composite. Scanning electron microscopy study shows that uniform particle distribution and good bonding between particles and epoxy polymer.

Effect of hBN Solid Lubricant Concentration on Machinability of Titanium (Ti-6Al-4V) Alloy

The prime rationale for designers to choose titanium in their designs for aerospace applications is its relative low weight for a given strength level and its relative resistance to high temperature. Excellent biocompatibility makes titanium as ideal material for many biomedical applications. Even though the titanium products are either sintered or cast into required shape, there is a need for machining in order to produce intricate shapes. However machining of titanium alloys poses many serious problems owing to the reactivity of titanium at high cutting temperatures and rapid tool wear. An alternative method to overcome this is by reducing the cutting zone temperature. This can be achieved by the addition of solid lubricants to regular cutting liquids and using it as minimum quantity lubrication (MQL) strategy. In this study, hexagonal boron nitride (hBN) powder with different concentrations (5, 10, 15 wt %) was mixed with water and used as a lubricant. Turning experiments were performed with TiAlN coated Tungsten carbide insert for a constant speed and variable feed rates. For comparison purpose, machining was carried out under dry conditions. Results indicate that the cutting zone temperature reduced drastically on addition of solid lubricant hBN with water. MQL conditions showed that cutting zone temperature decreased by several folds when compared to dry machining. However there was no significant decrease in temperature between 10 and 15 wt% hBN additions which indicates that 10% hBN addition proves to be optimal. This type of machining thereby paves way for sustainable manufacturing.

Effect of Magnesium Addition on Processing the Al-0.8 Mg-0.7 Si/SiCp Metal Matrix Composites

Metal matrix composites (MMCs) play a vital role in today’s engineering industries. Stir casting is one of the most inexpensive methods for the production of particulate reinforced metal matrix composites. However there are few problems encountered in stir casting such as the problem of poor wettability of the reinforcement particles in the matrix metal. The reinforcement particles have the tendency to either settle at the bottom of the crucible or they tend to float at the top of molten metal. This is due to the greater surface tension of the molten metal. Various techniques are available to improve the wettability of the ceramic particles in metal matrix which includes Particle treatment, Particle coating and Addition of alloying agent. In this work, Magnesium (Mg) was used as the alloying element to improve the wettability of SiC particles in the Al matrix. Mg is used to reduce the surface tension of molten aluminum (Al) thus promoting proper wetting. To understand the effect of Mg on improving the wettability of SiC in aluminum matrix, different weight percentages of SiC particles reinforced aluminum alloy 6061(AA6061) based MMCs were fabricated in stir casting method by adding Mg as alloying element. The cast specimens were subjected to microstructural analysis, tension tests and hardness tests. Results showed that addition of Mg with SiC in AA6061 matrix significantly improved the wetting between Al and SiC; subsequently MMCs possessed enhanced mechanical properties.

Mechanical Properties of Chopped Randomly Oriented Epoxy - Luffa Fiber Reinforced Polymer Composite

This paper presents the study of the tensile, compressive, flexural, impact energy and water absorption characteristics of the luffa fiber reinforced expoxy polymer composites. Luffa fiber reinforced epoxy resin matrix composites have been developed by hand lay-up technique with varying process parameters such as fiber condition (treated and untreated), chopped randomly oriented and different volume fraction (30%, 40% and 50%). Tensile strength varies from 9 MPa to 20 MPa, compressive strength varies from 75 MPa to 105 MPa, flexural strength varies from 15 MPa to 140 MPa and impact energy varies from 0.25 Joules to 1.45 Joules, as a function of fiber volume fraction. The optimum mechanical properties were obtained at 40% of fiber volume fraction of treated fiber composites. Fracture surface of the composite shows that pull out and de-bonding of fiber is occurred.

Corrosion Behavior of Aluminium-Boron Carbide-Graphite Composites

The corrosion behaviour of Al (6061)-B4C-Graphite was investigated. The Aluminium Metal Matrix Composites (AMMC) was fabricated through two step stir casting method. The composites were fabricated with various volume percentages of Boron Carbide (5, 10 &15%) and Graphite (5, 10& 15%). Corrosion studies of AMMC was investigated with 4%, 8%, 12% wt. % NaCl solution at room temperature. Also erosion-corrosion test were performed on the specimens in the NaCl solution with silica sand. Erosion-corrosion tests indicated that the rate of material loss mechanism is mechanical abrasion with enhanced corrosion. The material loss mechanism was significantly higher in the case of erosion-corrosion tests.

Effect of Sliding Speed on Tribological Properties of Microwave Sintered Copper-Graphite Composites

Effects of graphite content, and sliding speed on the tribological characteristics of copper-graphite composites under dry sliding condition were evaluated using a pin-on-disc tribometer. The worn surfaces of the composites were analyzed through Scanning Electron Microscopy (SEM). The experimental results revealed the improvement in wear resistance with increasing graphite content. The friction coefficient is also gradually decreasing upto 25 vol% graphite. Sliding speed has an effect on copper (5-15 vol%) graphite composites where as sliding speed has no effect in copper-(20-30 vol%) graphite composites. This difference is attributed to availability of self-lubricating graphite layer at the contact zone.