scholarly journals Mechanical Properties and Thermal Conductivity of Ytterbium-Silicate-Mullite Composites

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 671 ◽  
Author(s):  
Jie Xiao ◽  
Wenbo Chen ◽  
Liangliang Wei ◽  
Wenting He ◽  
Hongbo Guo
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Crack Deflection ◽  
Additive Concentration ◽  
Environmental Barrier Coatings ◽  
Pinning Effect ◽  
Al2o3 Phase ◽  
Ytterbium Silicate ◽  
Mullite Ceramics

Various Ytterbium-Silicate-Mullite composites were successfully fabricated by adding Yb2SiO5 into mullite ceramics and then using pressureless sintering at 1550 °C. The influence of Yb2SiO5 addition on the microstructure, mechanical properties, and thermal conductivity of ytterbium-silicate-mullite composites was investigated. Results show that the composites mainly consisted of a mullite matrix and some in situ formed Yb2Si2O7 and Al2O3 phases. By the addition of Yb2SiO5, the Vickers hardness of composites reached ~9.0 at an additive concentration of 5 mol %. Fracture toughness increased to ~2.7 MPa·m1/2 at the additive concentration of 15 mol %, owing to the trans-granular fracture and crack deflection of the pinning effect of the Al2O3 phase in the composites. With the increase of the Al2O3 phase in the composite, the thermal conductivity for the 15YbAM reached around 4.0 W/(m·K) at 1200 °C. Although the thermal conductivity increased, it is still acceptable for such composites to be used as environmental barrier coatings.

scholarly journals Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Ghadami ◽  
E. Taheri-Nassaj ◽  
H. R. Baharvandi ◽  
F. Ghadami
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Relative Density ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Vacuum Atmosphere ◽  
Sic Reinforcement ◽  
Microstructural Studies ◽  
Composite Samples

AbstractHfB2, Si, and activated carbon powders were selected to fabricate 0–30 vol% SiC reinforced HfB2-based composite. Pressureless sintering process was performed at 2050 °C for 4 h under a vacuum atmosphere. Microstructural studies revealed that in situ SiC reinforcement was formed and distributed in the composite according to the following reaction: Si + C = SiC. A maximum relative density of 98% was measured for the 20 vol% SiC containing HfB2 composite. Mechanical investigations showed that the hardness and the fracture toughness of these composites were increased and reached up to 21.2 GPa for HfB2-30 vol% SiC and 4.9 MPa.m1/2 for HfB2-20 vol% SiC, respectively. Results showed that alpha-SiC reinforcements were created jagged, irregular, and elongated in shape which were in situ formed between HfB2 grains and filled the porosities. Formation of alpha-SiC contributed to improving the relative density and mechanical properties of the composite samples. By increasing SiC content, an enhanced trend of thermal conductivity was observed as well as a reduced trend for electrical conductivity.

Preparation and Characterization of In Situ Nanocomposites of Graphene Nanosheets/Polyurethane

2019 ◽  
Vol 814 ◽  
pp. 90-95 ◽  
Author(s):  
Guang Lei Lv ◽  
Yuan Yuan Li ◽  
Chen Fei ◽  
Zhi Hao Shan ◽  
Jing Gan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Tensile Strength ◽  
Graphene Nanosheets ◽  
Graphene Sheets ◽  
Microstructural Properties ◽  
Wear Performance ◽  
Polyurethane Composites

Graphene nanosheets/polyurethane (GNS/PU) was prepared in situ by polymerization technique for the manufacture of PU safety shoes soles. The graphene nanosheets/polyurethane composites were characterized for their mechanical properties, thermal conductivity and abrasion resistance, and comparison is made with those of the neat polyurethane. The microstructural properties of GNS/PU were characterized by SEM. The results show that with the increase of the amount of graphene within the range of weight-percentages analyzed, the tensile strength of the composites gradually increases. The tensile strength of the GNS/PU composites increased to 64.14 MPa with 2 wt% GNS, compared with 55.1 MPa for neat PU. When the graphene sheets reached 2 wt%, the abrasion volume reached 71 mm3. Compared with the pure PU, the wear performance of GNS/PU composites was significantly improved.

FABRICATION AND PROPERTIES OF SILICONE RUBBER/ZnO NANOCOMPOSITES VIA IN SITU SURFACE HYDROSILYLATION

2011 ◽  
Vol 18 (01n02) ◽  
pp. 33-38 ◽  
Author(s):  
ZHIJIE YUAN ◽  
WEIHUA ZHOU ◽  
TING HU ◽  
YIWANG CHEN ◽  
FAN LI ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Silicone Rubber ◽  
Zno Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Rubber Matrix ◽  
Thermal Stabilities ◽  
X Ray ◽  
Vinyl Silane

The silicone rubber (SR) nanocomposites have been successfully prepared via the in situ hydrosilylation reaction in the presence of pristine ZnO and vinyl silane modified ZnO ( SiVi@ ZnO ) nanoparticles. The structure of the pristine ZnO and SiVi @ ZnO nanoparticles were analyzed by the Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The morphology, thermal stabilities, mechanical properties and thermal conductivity of the nanocomposites were also investigated. The results showed that the SiVi @ ZnO nanoparticles exhibit a better dispersion in the silicone rubber than the pristine ZnO nanoparticles. The corresponding silicone rubber/ SiVi @ ZnO (SR/ SiVi @ ZnO ) nanocomposites showed higher mechanical properties and thermal conductivity due to the better dispersion in silicone rubber matrix.

Preparation and properties of nylon 6/sulfonated graphene composites by an in situ polymerization process

RSC Advances ◽  
2016 ◽  
Vol 6 (51) ◽  
pp. 45014-45022 ◽  
Author(s):  
Chunhua Wang ◽  
Feng Hu ◽  
Kejian Yang ◽  
Tianhui Hu ◽  
Wenzhi Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
In Situ Polymerization ◽  
Nylon 6 ◽  
High Thermal Conductivity ◽  
Polymerization Process ◽  
Sulfonated Graphene

Nylon 6/sulfonated graphene composites with high thermal conductivity, good mechanical properties and excellent processability were prepared using sulfonated graphene as a precursor by an in situ polymerization process.

scholarly journals Polydopamine-Modified Al2O3/Polyurethane Composites with Largely Improved Thermal and Mechanical Properties

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1772 ◽  
Author(s):  
Ruikui Du ◽  
Li He ◽  
Peng Li ◽  
Guizhe Zhao
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
In Situ Polymerization ◽  
Mechanical Analysis ◽  
Thermal Interface Materials ◽  
Sem Images ◽  
Elongation At Break ◽  
Polyurethane Composites ◽  
Interface Materials

Alumina/polyurethane composites were prepared via in situ polymerization and used as thermal interface materials (TIMs). The surface of alumina particles was modified using polydopamine (PDA) and then evaluated via Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and Raman spectroscopy (Raman). Scanning electron microscope (SEM) images showed that PDA-Al2O3 has better dispersion in a polyurethane (PU) matrix than Al2O3. Compared with pure PU, the 30 wt% PDA-Al2O3/PU had 95% more Young’s modulus, 128% more tensile strength, and 76% more elongation at break than the pure PU. Dynamic mechanical analysis (DMA) results showed that the storage modulus of the 30 wt% PDA-Al2O3/PU composite improved, and the glass transition temperature (Tg) shifted to higher temperatures. The thermal conductivity of the 30 wt% PDA-Al2O3/PU composite increased by 138%. Therefore, the results showed that the prepared PDA-coated alumina can simultaneously improve both the mechanical properties and thermal conductivity of PU.

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