Fabrication of SiCf/SiC composites by alternating current electrophoretic deposition (AC–EPD) and hot pressing

Si‐B‐C ceramics were prepared through reaction sintering, and the influence of Al2O3 addition on the high‐temperature (1100‐1300°C) oxidation behavior of the material under air atmosphere was studied. The erosion behavior and mechanism are determined from the measurement of weigh changes, microstructure observations, and characterization of the generated oxides on postexposure specimens. Results show that Al2O3 is enriched in the oxidized layer, inhibiting the volatilization of B2O3 and impeding the crystallization ability of oxide (cristobalite). Narrower erosion layer and less weigh change are observed with Al2O3. Low‐frequency Raman results reveals that with the increase in Al2O3, the bending vibrations of the BO4 units and B‐O‐B stretching of the metaborate ring relative intensity are enhanced. Furthermore, high‐frequency Raman results shows that the relative proportion of high‐dimensional vibration modes Q3 and Q4 which result in a higher viscosity of melt and a greater resistance of oxygen diffusion are positively correlated with Al2O3.

Section: Introductionmentioning

confidence: 99%

The effect of Al₂O₃ on the high‐temperature oxidation resistance of Si‐B‐C ceramic under air atmosphere

Shan

Kan

et al. 2018

“…Figure B provides an OM image of the polished surface of the hot‐pressed SiC f /SiC composite. The hot‐pressed composites had an alternating layered structure of fiber‐rich and matrix‐rich layers, as shown in general in the composites fabricated by hot pressing . The matrix‐rich layers existed because of the surface adsorbed extra matrix phase.…”

Section: Resultsmentioning

confidence: 98%

“…The hot-pressed composites had an alternating layered structure of fiber-rich and matrix-rich layers, as shown in general in the composites fabricated by hot pressing. 24,31 The matrix-rich layers existed because of the surface adsorbed extra matrix phase. Small pores in the intrabundle regions were observed, while the matrix-rich region showed a highly densified morphology.…”

Section: Resultsmentioning

confidence: 99%

Formation of Ti₃SiC₂ interphase coating on SiC_f/SiC composite by electrophoretic deposition

Lee

Kim

Park

et al. 2017

To improve the oxidation resistance of SiC composites at high temperature, the feasibility of using Ti3SiC2 coated via electrophoretic deposition (EPD) as a SiC fiber reinforced SiC composite interphase material was studied. Through fiber pullout, Ti3SiC2, due to its lamellar structure, has the possibility of improving the fracture toughness of SiCf/SiC composites. In this study, Ti3SiC2 coating was produced by EPD on SiC fiber; using Ti3SiC2‐coated SiC fabric, SiCf/SiC composite was fabricated by hot pressing. Platelet Ti3SiC2 powder pulverized into nanoparticles through high‐energy wet ball milling was uniformly coated on the SiC fiber in a direction in which the basal plane of the particles was parallel to the fiber. In a 3‐point bending test of the SiCf/SiC composite using Ti3SiC2‐coated SiC fabric, the SiCf/SiC composite exhibited brittle fracture behavior, but an abrupt slope change in the strength‐displacement curve was observed during loading due to the Ti3SiC2 interphase. On the fracture surface, delamination between each layer of SiC fabric was observed.

“…13 It can be seen from Figure 1b that the characteristic peak of SiO 2 (1050 cm −1 ) disappears after HF etching, indicating that SiO 2 on the surface of SiC powder reacts with HF. [20][21][22] It can be seen from the zeta potential analysis that the removal of impure ions by pickling and HF etching SiO 2 , followed by calcination to form a new SiO 2 layer, is advantageous for the dispersion of SiC particles. 18,19 It can be seen from Figure 2 SEM pictures that after 2.0% HCl washing (Figure 2A), 20% HF etching ( Figure 2B), and 750°C calcination treatment ( Figure 2C), the particle size and morphology of SiC powder did not change greatly, and all of them showed irregular sheet or block structure.…”

Section: Impure Ion Analysismentioning

confidence: 99%

Influence of surface oxide layer of SiC powder on the rheological properties of its slurry

Gao

Wang

Zhao

et al. 2019

In this paper, the influence of surface oxide layer of SiC powder on the rheological behavior of its slurry was studied by acid washing, HF etching, and calcination oxidation processes. Zeta potential, particle size, inductively coupled plasma atomic emission spectrometry (ICP‐AES), energy dispersive X‐ray spectroscopy, and viscosity tests indicated the main factor that resulted in high viscosity of slurry is impure ions existing either on the powder surface or in the water phase, rather than the surface oxide layer. After the impure ions are removed, the surface oxide layer formed at a calcination temperature range of 400°C‐750°C does not cause an increase in the slurry viscosity, but contributes to an improvement in the rheological properties of SiC slurry.