To overcome the limitations of carbon/carbon (C/C) composites in long-term applications across a wide temperature range (1300–1700 °C), an integrated oxidation protection strategy has been developed through a one-step gaseous silicon infiltration (GSI) process, incorporating matrix modification and surface coating. This process leverages the high permeability of gaseous Si to simultaneously densify the porous matrix and in situ grow a SiC-Si protection system. The resulting C/C-SiC-Si composite demonstrates a service life exceeding 502 h at 1300and 1500 °C, and 149 h at 1700 °C. Crucially, after oxidation testing, the material retains a complete load-bearing structure and maintains over 54% of its original flexural strength (196 MPa). The superior performance is attributed to the continuous anti-oxidation network. This creates a mechanically interlocked interface between the coating and substrate, increasing the bonding strength by 31%, and establishes a continuous thermal expansion coefficient gradient that effectively mitigates thermal mismatch.

• MIC of Q235 steel with two different electron acceptors is investigated. • Corrosion by P. cashew is more severe with nitrate than sulfate. • More bacterial cells attach on steel in the nitrate medium. • Corrosion mechanisms under different electron acceptors have been proposed. Sulfate and nitrate exhibit different standard electrode potentials, potentially causing variations in corrosion mechanisms. However, their impact on bacteria as electron acceptors remains undocumented. This study aims to unveil corrosion behavior of Q235 steel in the presence of Pseudodesulfovibrio cashew ( P. cashew ) in sulfate and nitrate environments. Results indicate that sulfate and nitrate do not induce divergent corrosion outcomes under sterile conditions. Conversely, inoculation with P. cashew accelerates corrosion in both scenarios, with notably greater severity observed in the nitrate medium. The heightened corrosiveness of P. cashew when utilizing nitrate as an electron acceptor is attributed primarily to a lower Δ G 0’ , increased sessile cell population within biofilms, heightened bacterial metabolic activity, and a more extensive range of corrosion pathways.

• The dynamic influence of temperature variations on the development of TLC is systematically investigated. • The proportion of macro-cell current and micro-cell current in TLC under different temperatures is quantified. • The interplay between droplet condensation and corrosion development on TLC processes is described. This systematic study explores the effects of temperature gradients at top surface on top-of-the-line corrosion (TLC) of pipeline steel X65 under conditions of a constant high-temperature CO 2 -saturated aqueous phase at the bottom. Localized TLC behaviours were comprehensively analysed through wire beam electrode (WBE) techniques in combination with local electrochemical measurements. Results demonstrate significant differences in the impacts of micro-cell and macro-cell currents on the corrosion process under varying temperature conditions. At low top surface temperatures, uniform corrosion dominates, primarily driven by micro-cell currents. Conversely, increasing top surface temperature promotes localized corrosion and the dominance of macro-cell currents. Furthermore, corrosion products exhibit significant regional variations beneath droplet, highlighting a non-uniform nature of corrosion processes. These findings elucidate the temperature-dependent mechanisms of TLC and provide critical insights into the TLC process of pipeline steel.