Microwave heating controlled reactive melt infiltration for graphite‐Si‐SiC ceramics manufacturing

Abstract

In this work, we investigated a procedure which exploits microwave ovens to produce SiC-based components by reactive melt infiltration of silicon into graphite preforms. The employed oven is designed to grant optical access to the sample surface, which allows to measure its temperature evolution though a noncontact pyrometer. This signal was used as a feedback to control the power provided to the preform and as an experimental output whose analysis provides insight into the reaction mechanism. Specifically, it is found that complete infiltration is achieved much before the end of the reaction. The latter is not fully self-sustained as the global reaction rate continuously decreases with time until it is no more able to keep the temperature above the silicon solidification value. At that point, the reaction stops. The analysis of the processed samples proved that this procedure allows producing fully infiltrated samples without material failure by adjusting the heat provided during the infiltration stage rather than by tuning the preform structure and composition, which is the usual approach. The proposed method is less time and energy consuming than the standard one.

Influence of pyrolysis and Silicon infiltration on the properties of CMC parts shaped by composite flow molding

“…They formed by the reaction of Si with the graphitic structure of the carbon fibers. A similar behavior was observed in highly ordered Carbon polymorphs (graphite, diamond) reacting with Si 22,23 . Region F is characterized by SiC crystals formed by the precipitation of SiC in the molten Si, indicating that carbon atoms diffused in molten Si during processing 24 .…”

“…25 Finally region G shows the formation of thin SiC layer around the carbon fibers which is due to the concomitant spreading of Si vapors into the preforms. 23,25 Figure 4 shows the micrographs of the samples processed according the experimental plan of Table 2. They show that the samples infiltrated at low temperature (Figure 4A,C,E,G) present regions with dense SiC adhering to the preforms inner surface.…”

“…A similar behavior was observed in highly ordered Carbon polymorphs (graphite, diamond) reacting with Si. 22,23 Region F is characterized by SiC crystals formed by the precipitation of SiC in the molten Si, indicating that carbon atoms diffused in molten Si during processing. 24 This kind of reaction is most likely happening in the regions where pyrolytic (and thus amorphous) carbon is present.…”

EFFECTS OF THE AMOUNT OF STARCH AND THE HOLDING TIME ON THE SYNTHESIS OF SiC-TiC COMPOSITE POWDERS

“…Silicon carbide (SiC) has a series of advantages, such as high-temperature strength, high hardness, high thermal conductivity, good chemical stability, and excellent oxidation resistance. It is widely used in many fields, such as the chemical industry, the textile industry, in machinery, the military industry, and in energy, and its application prospects vary broadly [1][2][3]. Nevertheless, the room-temperature strength and fracture toughness of SiC are low, thereby limiting its application range [4].…”

Self-powered portable melt electrospinning for in situ wound dressing

“…In order to achieve in situ melt e-spinning, the conventional melt e-spinning device is an option [20][21][22][23][24][25][26][27][28][29][30][31]. However, these conventional melt e-spinning devices usually use a heating method such as resistance wires [22,23], laser heating [24,25], microwave heating [26], heated air and oil liquid [26][27][28][29][30][31] which need mains supply to melt the polymer for subsequent e-spinning, which is inconvenient in practical clinical and practical applications, especially where is no mains supply in the wild outdoors. In order to solve the problem of relying on the mains supply, the previous research used heating methods such as alcohol lamps, candles, etc.…”