Characterization of SiC ceramics with complex porosity by capillary infiltration: Part B – Filling by molten silicon at 1500 °C

Abstract

In Part A of this study, infiltrations experiments of porous SiC samples by hexadecane with poresize distributions comprising small and large pores were realized. Two successive stages were identified during the filling of these samples corresponding to the infiltration of the two types of pores. The experimental data were successfully treated with a new analytical function. In Part B, it was found that this function can also be applied to the analysis of the mass gain during molten silicon infiltration at 1500°C. Prior to silicon infiltration, it was found that the operating temperature induces a shift of the pore size distributions towards larger values. A dissolutionrecrystallisation mechanism can also occur during the infiltration of silicon. During the first stage, liquid silicon fills rapidly larger pores than hexadecane. The kinetics are significantly larger with liquid silicon. Consequently, the durations for the complete filling are very short with molten silicon.

Kinetics of liquid metal infiltration in TiC-SiC or SiC porous compacts

“…When the infiltration weight gain was stabilized, the contact with the liquids was broken and the temperature was directly decreased at a rate of 30°C.min -1 . The typical shape of the curves for the infiltration of molten silicon in a SiC compact is shown in Figure 3-b) [24]. Figure 3-c) shows a TiSi2-infiltrated compact.…”

Structural and Mechanical Properties of SiC-Rich By-Products of the Metal Grade Si Process

“…Coarse-grained silicate or reactive bonded SiC composites have been commercially used as heat-resistant material up to T=1400 0 C for many decades [20]. One of the main advantages of coarse grain SiC ceramic is high electrical and thermal conductivity and improved oxidation resistance [21,22,23,24,25]. Despite intensive improvement in traditional technologies and advanced approaches as additive manufacturing [26,27], self-propagating synthesis, field-assisted sintering, selective laser sintering [28], energy and material-consuming steps for the production of fine/coarse SiC powders and their consolidation remain a challenge.…”

Liquid metal infiltration of silicon based alloys into porous carbonaceous materials Part-III: Experimental verification of conversion products and infiltration depth by infiltration of Si-Zr alloy into mixed SiC/graphite preforms

“…SiSiC, also known as liquid silicon infiltration (LSI), involves infiltrating a porous carbonaceous preform by molten Si, which exothermically reacts with C to form SiC, resulting ideally in a dense composite. Over the past decades, Si-SiC ceramics have generated tremendous interest, which has led to the development of many variations of these materials, monolithic and particle/fibre reinforced CMCs, which can be obtained from different constituents and processes [3][4][5][6][7][8]. However, LSI has its disadvantages, the foremost being the presence of residual Si, rendering the composite unusable at temperatures near or above the melting point of Si.…”