Silicon carbide (SiC) is a promising material for high-temperature applications in various industries. Additive manufacturing (AM) of SiC has gained attention due to its challenging manufacturing process, and previous studies from our lab have shown that the creation of a silica gel layer on the surface of SiC using NaOH solution activated the surface and allowed 3D printing of SiC using water based binder in a powder bed binder jet printer. The dried silica gel layer binds adjacent SiC particles upon hydration during 3D printing at room temperature. The 3D printed green parts require a secondary surface activation by impregnating in NaOH solution and thermal treatment to enhance density and strength. The secondary surface activation technique creates an additional silica layer on the surface of SiC at room temperature which can lead to the growth of silica nanowire inside the pore of 3D printed SiC parts upon heat treatment. The hypotheses underlying this approach are twofold: (i) maximum growth of the silica nanowires will facilitate densification and mechanical properties, and (ii) the silica gel layer can mediate a strong bond between SiC and silicate minerals such as mullite. This thesis has three main objectives. First to understand the effect of post processing parameters including concentration of NaOH, thermal treatment temperature and dwelling time on silica nanowires growth and subsequent density and mechanical properties, second, to develop and validate a mathematical model for silica nanowires’ growth and ceramic strengthening, and the third objective is to examine the role of creating liquid mullite bonding agent instead of silica layer for the purpose of achieving denser SiC composite. This thesis is structured into two parts: (i) experimentally optimizing the post processing parameters for silica (SiO2) nanowire growth inside the pore of 3D printed SiC discs based on quantitative SEM analysis and development of a mathematical growth model for silica nanowire growth, and (ii) creating in situ synthesized liquid mullite as a secondary binder phase for the densification and strengthening of 3D SiC manufactured using powder metallurgy technique. In the first part, the effects of post processing parameters, such as NaOH concentration, sintering temperature, and time, on silica nanowire growth are investigated. The silica nanowires, grown through vapor-solid noncatalytic mechanism, depend on NaOH concentration, with 20% NaOH showing the highest nanowire number density. The optimal combination for nanowire growth involves impregnation with 10% NaOH and heat treatment at 550 °C for 6 hours and 1100 °C for 4 hours. This results in a nanowire number density of 55431 ± 9232 mm-2, with a compressive strength of 9.86 ± 1.4 MPa, density of 2.27 gcm-3, and porosity of 38.32%. Subsequently, a mathematical nanowire growth model was developed using experimental data in order to investigate the growth mechanism and understand the effect of reaction kinetics on the nanowire growth. The model accounted for the reaction kinetics controlling the formation of silica molecule and its subsequent deposition on nanowire top surface contributing to the growth of the nanowire. The change in nanowire length relation with respect to different post processing parameters obtained from the model showed a good agreement with the experimental data. The silica gel layer on the surface activated SiC particles transforms into cristobalite (SiO2) upon heat treatment which serves as a binding agent that holds the SiC particles together and controls the thermomechanical properties, density and porosity of the 3D printed SiC. Therefore, in the second part of this dissertation, addressing the limitations of cristobalite's mechanical and thermal properties in comparison to SiC, an in-situ mullite binding agent was developed. The composition of 85SiC/15ash exhibits the highest mechanical strength among the samples, with a compressive strength of 434 ± 20 MPa. XRD analysis reveals a composition of 81.8 wt% SiC, 11.4 wt% mullite, and 6.8 wt% cristobalite in the thermally treated sample. SEM-EDX analysis shows a concentration gradient of Al in cristobalite, enhancing the formation of functionally graded bonding zones between phases. The resulting SiC-mullite composite displays exceptional thermomechanical properties, including a nanoindentation elastic modulus of 370.9 ± 22.6 GPa, Vickers hardness of 11.5 ± 1.2 GPa, and high thermal shock resistance. The mullite binding phase resulted in a dense SiC composite with only 8% porosity. The resulting SiC-mullite composite is suitable for high temperature applications such as diesel motor parts, gas turbines, industrial heat exchangers, fusion reactor parts, high-temperature energy exchanger systems, and hot gas filters due to its high mechanical strength and thermal shock-resistance. This work demonstrated the potential of utilizing an in-situ mullite bonding agent instead of silica layer in additive manufacturing of SiC in the powder bed binder jet process for achieving a dense SiC parts with high thermomechanical properties.