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The corrosion behaviors of Ti3SiC2/Cu composites synthesized by spark plasma sintering technique were investigated at 900°C in three molten salts including NaCl, Na2SO4, and Na2CO3, and the related corrosion mechanism was discussed. The morphology and composition of the composites after corrosion were characterized by scanning electron microscopy and X‐ray photoelectron spectroscopy. The results indicated that the weight gain per unit surface area of the composites was negative in molten Na2CO3, while it was positive and relatively small in molten NaCl and Na2SO4. The high weight loss of the composites in molten Na2CO3 was owing to that in molten Na2CO3, an oxidation layer of the composites was dissolved, and oxygen diffused through the layer to corrode the substrate inside. Thus, in the molten Na2CO3, the composites exhibited a worse corrosion resistance. However, in molten NaCl and Na2SO4, an oxidation layer containing SiO2 and TiO2 was formed on the surface of the composites, inhibiting its further corrosion. Conclusively, the composites showed better corrosion resistance in molten NaCl and Na2SO4. [ABSTRACT FROM AUTHOR]

The electrochemical corrosion behaviors of Ti3SiC2/Cu composite and polycrystalline Ti3SiC2 in a 3.5% NaCl medium were investigated by dynamic potential polarization, potentiostat polarization, and electrochemical impedance spectroscopy. The polycrystalline Ti3SiC2 was tested on the identical condition as a control. The characterizations of XRD, X‐ray photoelectron spectroscopy, scanning electron microscope, and energy‐dispersive spectrometer were used to study the relevant passivation behavior and corrosive mechanism. The self‐corrosion current density of Ti3SiC2/Cu (6.46 × 10−6 A/cm2) was slightly higher than that of Ti3SiC2 (1.64 × 10−7 A/cm2). Under open circuit potential, the corrosion resistance of Ti3SiC2/Cu was better than that of Ti3SiC2. Ti3SiC2/Cu exhibited a typical passivation feature with a narrow passivation interval and a breakdown phenomenon. The better corrosion resistance of Ti3SiC2 was due to the more stable Si layer of the former. In comparison, for Ti3SiC2/Cu composites, Cu reacted with the reactive Si layers in Ti3SiC2 to form Cu–Si compounds and TiC, destroying the weak interaction between Si layers and Ti–C layers. In the other hand, the as‐formed Cu–Si compounds and TiC dissolved during the corrosion of Ti3SiC2/Cu in the 3.5% NaCl medium, causing to the destruction of the passivation film on its surface. [ABSTRACT FROM AUTHOR]

The corrosion behaviors of Ti 3 SiC 2 /Cu composites in dilute HNO 3 (11.6%) and concentrated H 2 SO 4 were investigated by the soaking method. The morphology, composition and elemental content of the composites before and after corrosion were analyzed to determine the corrosion products and the corresponding corrosion mechanism. The results found that the mass losses of the Ti 3 SiC 2 /Cu composites after soaking in the dilute HNO 3 and concentrated H 2 SO 4 for 50 days were 148.58 mg/cm2 and -2.90 mg/cm2, respectively, which indicated that the corrosion resistance of Ti 3 SiC 2 /Cu composites in concentrated H 2 SO 4 was superior than that in dilute HNO 3. It was deduced that in dilute HNO 3 , Cu in the Ti 3 SiC 2 /Cu composites reacted with dilute HNO 3 and dissolved in it, and Ti and Si in the Ti 3 SiC 2 /Cu composites reconstructed to form Ti 5 Si 3. The better corrosion resistance of Ti 3 SiC 2 /Cu composites in concentrated H 2 SO 4 was owing to a passivation film consisting of TiO 2 and SiO 2. Moreover, the appearance of the formation of CuO in the initial corrosion further strengthened its corrosion resistance in concentrated H 2 SO 4. [ABSTRACT FROM AUTHOR]