Property and Oxidation Behaviours of (Mo,Cr)Si2 + ZrO2 Composite Produced by Pressure-Less Sintering
- 1 Department of Materials and Manufacturing Technology, Chalmers University of Technology, Gothenburg, Sweden
- 2 Heating Systems Division, Sandvik Heating Technology AB, Hallstahammar, Sweden
- 3 Material Technology, Siemens Industrial Turbomachinery AB, Finspong, Sweden
- 4 Heating Systems Division, Sandvik Heating Technology AB, Hallstahammar, Sweden
Abstract
A composites of (Mo 0.9 Cr 0.1 )Si 2 + 15vol% ZrO 2 was prepared with powder metallurgy and Pressure- Less Sintering (PLS) method, aiming at applications of high temperature structural materials. Mechanical properties of the composites were assessed with hardness, indentation fracture toughness K c and K IC tested using SEVNB, flexure strength at room temperature and 1200?C, and iso thermal oxidation at 1400 ?C . The results showed that the native silica oxide and molybdenum-oxides on the silicide feedstock surface were significantly reduced in terms of Cr-alloying. (Mo 0.9 Cr 0.1 )Si 2 and its composite also exhibited improved sinterability and grain growth, owing to the presence of (Cr, Mo) 5 Si 3 at grain boundaries. Fracture toughness of the composite was increased by a factor of 1.6 to that in the monolithic silicide. Mechanical property of the composite at high temperature was not affected by Cr addition. However, the high temperature oxidation resistance was greatly improved in the (Mo 0.9 Cr 0.1 )Si 2 + 15vol% ZrO 2 compared with the non Cr-alloyed counterpart. The Cr-alloying effects on the microstructure, fracture behaviour, and high temperature oxidation resistance were discussed.
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