Investigation on the wear behaviour and properties of RHA reinforced 7075 aluminium t6 composites produced by vacuum infiltration

Aluminum matrix composites containing hard ceramic particles have higher strength, hardness and wear resistance than conventional materials. However, the high cost of hard ceramic reinforcements has led researchers to obtain ceramic reinforcement from organic wastes such as rice husk and eggshell, and they are looking for ways to increase the hardness and wear properties by reinforced these organic wastes. In this study, 1, 2, and 4 vol.% rice husk ash (RHA) were added to AA7075 metal matrix. Samples were produced in a steel tube under 550 mmHg vacuum at 750 °C for 3 minutes. T6heat treatment (aging) was applied to the samples. The density, porosity, and hardness of non-aged and aged samples were measured and compared. In addition, SEM and EDS analysis of aged samples were performed and wear properties under 20 N load was investigated. While the hardness and the porosity of T6 heat treated composites increased with increasing reinforcement volume ratio, T6 heat treatment did not improve the hardness and the wear properties of the composites significantly compared to unreinforced (0 vol%) sample. Wear tests showed that the mass loss increased with the increment of reinforcement-volume ratio. Increasing RHA content resulted in worsening the wear behavior of composites because of the poor wettability of RHA particles

Interfacial microstructure evolution and shear strength of MWCNTs-reinforced Sn-1.0Ag-0.5Cu (SAC105) composite solder interconnects on plain Cu and ENIAg surface finish

The combined effect of MWCNTs (multi-walled carbon nanotubes) and ENIAg (Electroless Nickel Immersion Silver) surface finish on the formation of interfacial microstructure and shear strength of the Sn-1.0Ag-0.5Cu (SAC105) solder was investigated in this study. Plain and composite solders (SAC-xCNT; x = 0, 0.01, 0.05 and 0.1 wt%) were successfully synthesized through the powder metallurgy route and afterwards soldered on the ENIAg surface finish and plain Cu substrates. Detailed analysis of the microstructure revealed the formation of the Cu6Sn5 IMC at the SAC solder/Cu substrate interface of the SAC-xCNT/Cu solder interconnects. Whereas, the Ni3Sn4 IMC and (Cu,Ni)6Sn5 IMC appeared at the SAC solder/ENIAg substrate interface of the SAC-xCNT/ENIAg. The MWCNTs-reinforced SAC composite solder interconnects exhibited thinner interfacial IMC layer thicknesses relative to the plain counterparts for both substrates used. Given the prospects of the ENIAg as a reliable surface finish material, the SAC-xCNT/ENIAg exhibited IMC thickness values within the range of 2.98–2.65 µm as compared to the 5.23–3.61 µm demonstrated by the SAC-xCNT/Cu. Overall, the strengthening capacity of the MWCNTs was well-defined in both sample grades, with the SAC-0.05CNT/Cu and SAC-0.05CNT/ENIAg exhibiting the highest shear strength values of 10.23 MPa and 11.14 MPa, respectively