Microwave Synthesized Functionally Graded Superhard Cladding

Abstract

Functionally Graded Clads are tailored layers of materials with gradually changing properties along thickness of cladding. In the present work we developed Ni based EWAC-TiB2 FGC comprising 100% EWAC, 90% EWAC + 10% TiB2 and 80% EWAC + 20% TiB2 as 1st, 2nd and 3rd layers respectively, using microwave hybrid heating technique in a domestic microwave applicator operating at 900 W power, 2.45 GHz frequency for a duration of 480 s. The average thickness of FGC was ~ 900 µm with each layer varying in the range of 200 –300 µm. Functionally graded clads were developed earlier using microwaves in multiple steps which causes sharp boundaries between two layers and eventually stresses. The focus of present work was on developing all the three layers of functionally graded clads in single step processing. Microstructural investigations clearly indicate good metallurgical bonding between all the layers of clad and it is also evident that dilution of first clad layer with substrate surface is achieved. The Vickers microhardness profile of the FGC layers obtained at a load of 200 g for 10 s dwell time showed an increase in hardness value with an increase in the amount of reinforced TiB2 particles. Wear test also showed 60% wear resistance in FGCs.