Authors: Hyo Jin Kim, Do Won Seo, Jae Kyoo Lim, Toru Fujii
417
Authors: Dong Mei Zhu, Hong Na Du, Fa Luo, Wan Cheng Zhou
Abstract: Porous C/C composite with certain porosity prepared by Chemical vapor infiltration
(CVI) was chosen as the preforms to develop the C/C-SiC composites through precursor infiltration
and pyrolysis(PIP), using PCS (polycarbosilane) as the precursor and divinylbenzene as solvent and
cross-linking reagent for PCS. The effect of the infiltration solution with different PCS/DVB ratio on
the final density, microstructure, and mechanical properties of composites was investigated and the
proper PCS/DVB ratio to prepare the C/C-SiC composites was suggested. The experimental results
showed that the final densities and the mechanical properties of the composites were close related to
the PCS/DVB ratio. Higher PCS/DVB ratio resulted in higher final density and better mechanical
properties, but not the highest PCS/DVB ratio could get the best mechanical properties. The main
reason is that too high PCS/DVB ratio will make the infiltration process become difficult and lead to
the formation of lots of pores in the final composite, at last lowers the mechanical properties. It is
believed that the 50% PCS content is proper to prepare the C/C-SiC composites. The composite from
50% PCS infiltration solution could get the final density of1.696g/cm3, the flexural strength of
171Mpa, and shearing strength of 21.6Mpa, which are the best mechanical results among the obtained
materials.
1501
Authors: Sedigheh Salehi, Omer Vander Biest, Jef Vleugels
Abstract: 1.75 mol % Y2O3-stabilized ZrO2-based composites with 35-95 vol % TiN were fully
densified by hot pressing for 1 hour at 1550°C under a load of 28 MPa. The TiN grain size was
found to increase with increasing TiN content, resulting in a decreasing hardness and strength. The
best mechanical properties, i.e., an indentation toughness of 5.9 MPa.m1/2 in combination with a
Vickers hardness of 14.7 GPa and an excellent bending strength of 1674 MPa were obtained for the
composites with 40 vol % TiN. The active toughening mechanisms were identified and their
contribution to the overall composite toughness is discussed. Transformation toughening was found
to be the primary toughening mechanism in all investigated composites.
135
Authors: Tao Jiang, Hai Yun Jin, Zhi Hao Jin, Jian Feng Yang, Guan Jun Qiao
Abstract: The machinable B4C/BN ceramics composites were fabricated by hot-pressing sintering
process at 1850oC for 1h under the pressure of 30MPa. The mechanical property, thermal shock
behavior and machinability of the B4C/BN ceramics composites were investigated in this article. The
experimental results showed that the fracture strength and fracture toughness of the B4C/BN
nanocomposites were significantly improved in comparison with the B4C/BN microcomposites. The
Vickers hardness of the B4C/BN nanocomposites and B4C/BN microcomposites decreased gradually
with the increasing content of h-BN, while the machinability of the B4C/BN nanocomposites and
B4C/BN microcomposites were significantly improved. The B4C/BN ceramics composites with the
h-BN content more than 20wt% exhibited excellent machinability. The thermal shock resistances of
the B4C/BN ceramics composites were better than that of the B4C monolith, and the thermal shock
resistance of the B4C/BN nanocomposites was much better than that of the B4C/BN microcomposites.
The thermal shock temperature difference (-Tc) of B4C monolith was about 300oC, while the -Tc of
the B4C/BN microcomposites was about 500oC, the -Tc of the B4C/BN nanocomposites was about
600oC.
53
Authors: Ying Cao, Li Pan
Abstract: In the present investigation, resin transfer molding has been used to produce high quality carbon fiber epoxy composites and nanotube-reinforced carbon fiber epoxy composites. To study the influence of carbon nanotubes (CNTs) on improving the mechanical properties and fatigue life, the tension-tension fatigue test has been carried out on those two kinds of material in the fiber direction. The damage mechanism in the fiber directions was analyzed by X-ray radiography and electron microscopy. The results show that CNTs pulled out, rapture and bridged cracks during the test, the results also show that CNTs possess an obvious potential on improving the property of carbon fiber epoxy composite, especially for properties that dominated by matrix.
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