Abstract
SiC fiber reinforced SiBCN ceramic matrix composites (CMCs) have been prepared by mechanical alloying and consolidated by hot pressing. During the sintering process, amorphous SiC fibers crystallized seriously and transformed into β-SiC. Meanwhile, the interfacial carbothermal reactions caused the strong bonding between the matrix and fibers. As a result, SiCf/SiBCN fractured in a typical catastrophic manner. Room-temperature mechanical properties reached the maximums for the CMC samples sintered at 1900 °C/60 MPa/30 min. The density, flexural strength, Young’s modulus and fracture toughness are 2.56±0.02 g/cm3, 284.3±17.9 MPa, 183.5±11.1 GPa and 2.78±0.14 MPa·m1/2, respectively.
Highlights
SiBCNceramicshavebeenwidelyinvestigateddueto their better high-temperature properties such as oxidation[1,2,3]andcreepresistance[4,5], whichare expected to be applied in aerospace and anti-ablation structuresinthefuture
Ltd., Beijing, China) and graphite powder(8.7 m, 99.5%inpurity, Qingdao HuaTai LubricantSealing S&TCo.Ltd.,China)wereusedasstarting materials intheexperiment.Thecomposition wasdesignedas Si:C:BN=2:3:1 in molar ratio. This designation depended on the literature and our previous research to compare with precursor derived ceramics[20]
X-ray diffractometer (40kV/100mA,D/max- BCuK,RigakuCorporation, Japan)wasusedtoobtaintheX-raydiffraction(XRD) spectra at 2 =10°–90° with a scanning speed of 4(°)/min.Theas-milledSiBCNpowderandfracture morphologies of the ceramics were observed by scanningelectron microscopy(SEM,30kV, Quanta 200FEG, FEI Co., USA)
Summary
SiBCNceramicshavebeenwidelyinvestigateddueto their better high-temperature properties such as oxidation[1,2,3]andcreepresistance[4,5], whichare expected to be applied in aerospace and anti-ablation structuresinthefuture. Various methodsto fabricate these novel ceramics have been attempted such as precursor infiltration and pyrolysis (PIP) [6,7], physical vapor decomposition (PVD) [8,9] and mechanicalalloyingandhotpressing(MA–HP)[10]. Amongthe reinforcements for precursor derived ceramics, fibers have been widely used in. JAdvCeram2015,4(1): properties, silicon carbide fibers have been chosen as the reinforcement of SiBCN matrixin our recent research [17]. SiCf/SiBCN CMCs have been prepared by mechanical alloying and hot pressing. Mechanical properties and microstructures of the CMCs werecarefullystudied,especiallythebehavior of carbon diffusion in the adjacent area of fibers. These resultsmaybehelpfulforthechoiceofcoatingonSiC fibers and applications offiberreinforced SiBCN composites
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