6533b831fe1ef96bd1298387

RESEARCH PRODUCT

Electrical and thermomechanical properties of CVI- Si3N4 porous rice husk ash infiltrated by Al-Mg-Si alloys

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Abstract The effect of following processing parameters on the electrical and thermomechanical properties of Al/Si3N4 deposited silica composites was investigated using the Taguchi method and analysis of variance (ANOVA): infiltration temperature and time, atmosphere, effect of Si3N4 coating, porosity content in the preforms, and magnesium content in the alloy. The contributions of each of the parameters to modulus of elasticity, electrical resistivity, coefficient of thermal expansion (CTE), and thermal diffusivity of the resulting composites were determined. The maximum modulus of elasticity and electrical resistivity of obtained composites were 265 GPa, and 1.37 × 10−3 Ω m, respectively. These values were achieved in composites fabricated from Si3N4 preforms under conditions of temperature (1200 ০C), time (120 min), porosity of 40 vol %, Al-9Mg-13Si alloy, in the atmosphere of N2. The minimum value of CTE obtained was 5.3 × 10−6/০C. This value was achieved in composites fabricated from Si3N4 coated silica under the same mentioned conditions. The thermal diffusivity of four fabricated samples (two samples with the highest and two samples with lowest electrical resistivity) was measured. The results show that the highest value of thermal diffusivity (20.4 mm2/s) among fabricated composites is belonged to the one with highest value of electrical resistivity.