Influence of zinc (Zn) powder on the microhardness characteristic and microstructure properties of stainless steel SS304 hybrid joint using low power microwave heatingEinfluss von Zinkpulver auf die Mikrohärte und die Gefügeeigenschaften einer Hybridverbindung aus rostfreiem Stahl (X5CrNi18-10) unter Verwendung von Mikrowellenerwärmung mit geringer Leistung

Microwave hybrid heating (MHH) process is a unique and novel approach of joint materials. Several lightweight materials (medium and high melting point) such as nickel, copper and aluminum have been successfully joined in the past research. However, small dimensions and low melting point of light weight materials such as zinc (Zn) metal or zinc (Zn) powder were always being a challenging mere for creating bond via any joining techniques. The sheets of stainless steel SS304 (17 mmx7.9 mmx0.2 mm) have been fabricated and joined at lap joint by using novel Microwave hybrid heating technique with mini heat chamber of 2.45 GHz of frequency and 200 W-360 W of microwave power, using pure zinc powder (99.9 %) as an interface material. Epoxy rate and exposure time have been varied from 10 % to 20 % and 2 min to 4 min, respectively. A developed heat chamber has been set in domestic microwave oven properly as proposed. To evaluate the microstructure correlation and microhardness at joint interface, the field emission scanning electron microscopy (FESEM - EDS), x-ray diffraction (XRD) and Vickers hardness were used. For the experimental studies, it had found an excellent bonding was produced at interface layer between the upper and lower sections with good penetration rate of 360 W of microwave power, 4 min of exposure time and 20 % of epoxy rate as the 183.1 HV 0.05 of excellent microhardness and the intermetallic phase of iron-zinc (FeZn11), nickel-zinc (NiZn) and nickel-zinc (NiZn3) were observed at interface layer. The stainless steel was successfully joined by zinc powder under microwave hybrid heating. The experimental testing found a direct relationship among the variation of microwave power, exposure time, and epoxy rate. Increasing of epoxy rate eventually reduces the porosity and cracks and increases the evaporation rate which created excellent bonding between the powder particles and parent metal. image