Issue 48

P.H. Nayak et alii, Frattura ed Integrità Strutturale, 48 (2019) 370-376; DOI: 10.3221/IGF-ESIS.48.35 372 quantity of Cu-Zn alloy ingots were charged into the heating furnace to liquefy. Though the Cu-Zn alloy melts at 1080˚C, the melting furnace was superheated to a temperature of 1150˚C. Thermocouples were used to measure temperature. The melt metal in crucible was then degassed to remove unwanted byproducts using a chemical called hexa-chloro-ethane (C 2 Cl 6 ) upto 3 mins. A steel impeller used was coated with a ceramic material known as zirconium which is used to agitate by rotating the molten metal such that the vortex is created. The process of stirring was carried out at a speed of 300 rpm & the impeller was immersed for about 60% height of molten metal from the top surface of melt within the crucible. Simultaneously during the process of stirring the pre-calculated amount of reinforcement was added into the vortex in two-stages, to ensure good wet-ability stirring was continued for upto 5 mins. The reinforcing materials ZrO 2 was preheated upto 500˚C in oven to remove moisture content before adding it into molten metal vortex. Now, Cu-Zn alloy along with 4 wt. % ZrO 2 particulates were poured into solid cast iron mould to get a composite after solidification. Similarly, Cu-Zn-8 and 12 wt. % of ZrO 2 composites were fabricated for the further studies. The microstructural analysis completed by utilizing SEM instrument. Tests around 5 mm thickness across taken from the casting samples and were cleaned appropriately. A reagent named Keller's was utilized to etch the examples. Hardness of as cast copper-zinc-ZrO 2 amalgam composites were coordinated to know the influence of nano scale ZrO 2 particles in the system material ASTM E 10 standard [11]. The cleaned precedents were striven for their hardness, using Brinell hardness testing machine, which is having a ball indenter and applying a load of 250 kg and tolerate time of 30 seconds, three courses of action of readings were noted at better places of the sample and an average of all the value was used for figuring. The tensile properties of the prepared samples are established as per the ASTM E8 method upon tension test piece of gauge-diameter 9mm with gauge-length of 45mm. Metal & its alloys are to be designed to provide material properties tailored to applications. Universal testing machine (UTM) is used to conduct tensile test to find out the effect of nano ZrO 2 particulates on tensile behavior of Cu-Zn alloy composites. R ESULTS AND DISCUSSION Microstructural Analysis ig. 1(a) shows microstructure of as cast copper-10% zinc alloy, fig. 1b represents Cu-Zn-12 wt.% of nano ZrO 2 composites. The SEM micrographs reveal almost uniform distribution of ZrO 2 particulates throughout the matrix as observed in the fig. 1b. Uniformly distributed particulates increase the overall strength and other properties reducing the porosity of the MMC. Fig. 2 is the EDS spectrum of copper-zinc and 12 wt.% of nano ZrO 2 reinforced composites. EDS spectrum revealed the presence of nano ZrO 2 particles in the copper-zinc alloy matrix in the form of Zr and O elements along with Cu and Zn matrix elements. (a) (b) Figure 1 : SEM micrographs of (a) as cast copper-zinc alloy (b) copper-12 wt. % ZrO 2 composite F