Ramification of thermal expansion mismatch and phase transformation in TiC-particulate/SiC-matrix ceramic composite

Abstract

This article presents a microstructural study on the role of incipient residual stress relaxation in TiC-particulate/SiC-matrix ceramic composite toughened by thermal expansion mismatch and phase transformation toughening. Exhaustive microstructural studies was undertaken using scanning electron microscopy and transmission electron microscopy following a wear test. It was found that the superposition of hydrostatic tensile stress induced at the surface following the sliding contact on the inherent residual stresses locked in the composite led to a relaxation and/or reduction in the residual stresses. Stress relaxation presented a wider implication for the tribological properties of this ceramic matrix composite (CMC) in the form of a grain-scale rippling microstructural phenomena. Dear Editor,Many thanks for the opportunity to address the reviewers comments and recommendations. All latest corrections that have been carried out in the manuscript are highlighted in red text below the reviewers comment. Reviewers' comments:1. In the article title, SiC-TiC ceramic matrix could be added to clarify the research object of this article.This has now been included in the title as advised 2. It was suggested some references that research on SiC based ceramic matrix could be added, like Ceramics International 46 (2020) 5159-5167 and so on.This reference has now been included as advised 3. Please confirm if there is any sintering additive during the SPS process.No sintering additives was employed and this has now been stated in the manuscript 4. Please add the heating rate of SPS process.Heating rate 100 °C/min was employed and has been stated in the manuscript 5. It was suggested that a XRD result can be added in the article to investigate the phase transformation in larger scale than TEM.XRD result has now been added to highlight phase transformation 6. It was suggested that the thermal expansion data of SiC and TiC could be added in the article.A table showing thermal expansion data of all the phases in the composite system has now been added to the manuscript

Slurry‐impregnating hot‐press sintered silicon carbide nanofiber/silicon carbide composites with Al‐B‐C as sintering additives

“…32 Figure 7B shows the crack extension pictures of the composites which were prepared at lower temperatures and pressure, it is consistent with the weak interfacial crack extension mode, indicating that the amount of SiC powder infiltrated into the SiC nf layer is less at this temperature and pressure, the bonding strength between the SiC matrix layer and the SiC nf layer is low, and the sectional morphology of the composites is rougher, which is consistent with the sectional morphology of Figure 7E. As shown in Figure 7C, crack twisting occurs within the composite when the interfacial bonding strength is high, there was the existence of residual stresses between neighboring layers because of the thermal mismatch, 33 it will provide additional resistance during crack extension to improve apparent fracture toughness at the material interface. Figure 7D shows the crack extension pictures and sectional morphology of the composites prepared at higher temperatures and pressure, the bonding strength of the SiC matrix layer and the SiC nf layer are high at this temperature and pressure, and the sectional morphology of the composites is relatively flat, as shown in Figure 7F, SiC nf binds more tightly to the SiC matrix, so the mechanical strength of the composite is enhanced.…”

Microstructure and mechanical properties of CuZn-Al2O3 nanocomposites produced by friction stir processing

“…Furthermore, the difference between thermal coefficient of matrix and reinforcements cause to production of dislocations during cooling cycle of process, which is called usually thermal mismatch mechanism ( Δ TM ) . Thermal mismatch mechanism is one of the main mechanisms causing higher yield strength in composites in which the generated geometrically necessary dislocations results in work hardening [23]. Moreover, the Orowan mechanism ( Δ OR ) can also contribute in strengthening of composites.…”