Mechanical Properties, Tribology and Electrochemical Studies of Al/Fly Ash/Eggshell Aluminium Matrix Composite

This work was carried out to investigate the effect of carbonized eggshells (CES) and fly ash on the microstructure, mechanical properties, wear, and corrosion characteristics of Al-Si12. The weight fraction (wt.%) of the CES particles was kept constant at 2.5 wt.%, while that of fly ash was varied at 2.5 wt.%, 5.0 wt.%, 7.5 wt.%, and 10.0 wt.%. The selected fabrication route was stir casting. The x-ray diffraction (XRD) analysis of the cast aluminum matrix composites (AMCs) revealed the presence of phases including α-aluminum, SiO2, and Si with the formation of the intermetallic CuAl2 phase. The microhardness of the cast samples increased with increasing weight fraction of the reinforcements up to the 7.5 wt.% fly ash sample. The tensile strength and compressive strength were highest for the 2.5 wt.%/CES 2.5 wt.%. Tribology studies showed that the lowest wear rate of 4.91 × 10-5 mm3/Nmm was obtained for the 2.5 wt.% fly ash sample, while the corrosion studies showed that the corrosion rate of 2.70 × 10-5 g/hr was lowest for the 2.5 wt.% fly ash as well.

Thermomechanical and Tribological Properties of SiC/Gr Reinforced Hybrid Aluminum Composite for Disc Brake Application

The disc brake motorcycle material has been developed by using aluminium matrix composite (AMC) reinforced with matrix particulate ceramic. The composite has many advantages: lightweight, high re-sistance to wear, and controllable strength by adjusting the reinforcement materials percentage. The main issue is the environmental factor that influences the surface properties of the disc. The research aims to study thermomechanical and tribology characteristics to determine the effect of the environmental factor on the composite's wear-out rate. The disc is made from matrix Al7Si6Mg9Zn composite matrix with 10% SiC and 10% graphite (v/v). The disc is produced by squeeze casting method and heated for 4 hours at 180 °C as artificial aging heat treatment. Thermomechanical characteristics are carried out by observing the temperature changes when a load is introduced to the disc. The pin-on-disc method is applied at three different speeds (60, 80, and 100 rpm) under the wet and dry surface on the disc for observing the tribo-logical properties. Thermomechanical characteristics of the disc are average braking time is 3.72 seconds, where the average braking distance is 515.8 cm at speed 40 km/hour with the average temperature of 46.12 °C. The wear-out rate results are steady, where the highest wear out rate for the dry surface is 0.725 mm3/N.m and 6.133 mm3/N.m for the wet surface at 100 rpm.

Milling of an Aluminium Matrix Composite Using MCD-Tipped Tools with Adjusted Corner and Minor Cutting Edge Geometries

Aluminium matrix composites (AMCs) represent suitable materials for lightweight design applications. The abrasive ceramic reinforcements typically require diamond cutting materials to prevent excessive tool wear. In milling with diamond cutting materials the influence of cutting parameters was already examined to a significant extent. Investigations concerning the effect of modified tool geometries are limited and the potentials with regard to the geometrical and physical surface properties are unclear. Accordingly, experimental investigations in milling of a 10 vol.% SiC particle-reinforced aluminium wrought alloy EN AW-2017 T4 were addressed. The effect of modified corner and minor cutting edge geometries were investigated based on mono crystalline diamond (MCD)-tipped tools to benefit stable process conditions. The results indicated achievable areal roughness values in the range around 0.2μm. Especially the application of the lowest cutting edge angle and a trailing minor cutting edge led to strong fluctuations of the surface parameters. The lowest valley void volumes were achieved with an arched minor cutting edge. Generally, finish machining led to stronger compressive residual stresses compared to the state prior to machining. The strongest increase was achieved using a corner radius combined with a straight minor cutting edge. It is concluded that reduced effective radii generating the surface enable an acceptable surface structure and strong compressive residual stresses and should be addressed in further investigations.