Microwave Heating Of Bulk Metallic Materials And Its Effect

In this paper,bulk metallic materials coated with microwave absorbing coating were heated rapidly by microwave.The heating properties of bulk metallic samples coated with different constituents of microwave absorbing coatings were investigated.The microstructural and mechanical characterization of microwave heated TC4 titanium alloys were also studied in comparison with that of the conventional heated samples.The results showed that,under the premise of ensuring the fluidity of coatings,for the coatings mainly including SiC microwave absorbing materials,the heating effect was increased with increased SiC content.The best microwave heating effect can be achieved when the mass fraction of SiC particles is about 73%.However,its heating ability is limited,with the maximum temperature of only 730℃ after heating for 20 minutes.The heating ability of the coating in high temperature range can be improved by incorporation of alumina.The best microwave heating effect of the coating can be achieved when the mass ratio of Al2O3:SiC is 3:2,with the experimental observation that the sample could be heated to the desired temperature(800 ℃)within 15 minutes.Furthermore,it is obvious that the efficiency of microwave heating is much better than that of the conventional heating method.The microstructures and mechanical properties of TC4 titanium alloys treated respectively by microwave heating and conventional heating method after solution treatment were analyzed.The results indicated that the average grain size of TC4 titanium alloy after microwave heating was about 6.59 μm,which was significantly smaller than that of conventional heating,with the average grain size of 12.60 μm.This is because the heating rate by microwave is fast,resulting in the short time experiencing at high temperature region and the adjoint short grain-growth time.It’s indicated that microwave heating can refine the grain size of the bulk metals compared with the existing conventional heating method.Mechanical property testing results showed that the strength and plasticity of titanium alloys treated by microwave heating is higher than that of titanium alloys treated by conventional heating,namely that the yield strength,elongation and percent reduction of area are increased by 21.87%,17.28%and 11.91%,respectively.The fracture morphology of TC4 titanium alloy tested at room temperature was investigated.In comparison with the results of the samples heated by conventional heating,it was observed that the dimensions and depths of dimple of the microwave heated sample were increased,indicating better plasticity and toughness.