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RISS 인기검색어
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- 저자 : Baharvandi Hamid Reza (검색결과 2 건)
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Pressureless sintering of SiC matrix composites reinforced with nano-β-SiC and graphene
Razmjoo Ali,Baharvandi Hamid Reza,Ehsani Nasser 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.5
Silicon carbide (SiC) is an effective material for high-temperature engineering applications owing to its desirable properties such as high elastic modulus, high hardness, and melting temperature, high thermal conductivity, good corrosion and oxi- dation resistance, low density, and coefficient of thermal expansion compared with other advanced ceramics. Nevertheless, poor sinterability and low toughness limit its use, which can be overcome using appropriate additives. In this study, the eff ect of different amounts of nano-β-SiC (0, 5, 10, and 15 wt.%) and graphene (0, 1, 2, and 3 wt.%) particles on the sinterability behavior and microstructure of SiC composite has been investigated. After weighing, dispersing nano-β-SiC and graphene, and mixing the starting materials, milling was carried out at 180 rpm for 3 h. The materials obtained were then compressed uniaxially under a pressure of 75 MPa and then were compressed again through CIP under 150 MPa. To remove volatile products, the pyrolysis process was performed at 800 °C under Ar atmosphere. Finally, the samples were sintered at 2200 °C for 2 h by the pressureless sintering process. XRD analysis was used to investigate the phases and FESEM images were used to study the microstructure. According to the XRD patterns, β-SiC particles were converted to α-SiC, which was accompa- nied by the elongation of SiC grains. Also, no reaction was observed between graphene and the SiC matrix. According to the FESEM images, the samples containing 5 wt.% nano-β-SiC and 1 wt.% graphene showed a uniform distribution of rein- forcement particles but with increasing the amount of the reinforcement particles, agglomeration was observed. According to the results, upon increasing the nano-β-SiC up to 5 wt% and graphene up to 1 wt.%, all the measured properties including relative density, and linear shrinkage improved and reached 99.04%, and 18.01%, respectively. However, with increasing the additives, these properties deteriorated due to increasing porosity and agglomeration in the composite structure.
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Effect of TaB2 on densification and hardness of tantalum carbide/boride composites
Behzad Mehdikhani,Gholam Hossein Borhani,Saeed Reza Bakhshi,Hamid Reza Baharvandi 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.5
Tantalum carbides/boride composite were synthesized by spark plasma sintering (SPS), using the powder mixtures of TaC andB4C as the starting materials. In this work densification, phase formation, microstructures, and mechanical properties of thematerials were investigated. The densification of tantalum carbide (TaC) was enhanced by adding 2.0 wt% B4C, reaching 97%relative density by SPS at 1900 oC using a 30 MPa applied pressure. X-ray diffraction analysis identified two phases, TaC andtantalum diboride (TaB2), with no peak shifts, indicating a solid solubility was not significant at these temperatures. Densificationof TaC was enhanced while the grain growth was suppressed by adding 2 wt% B4C, which allowed mechanical properties to beanalyzed. Relative density of > 97% was achieved for TaC with B4C additions by SPS at 1900 oC. By comparison, additive-freeTaC could be sintered to only 76% relative density at 1900 oC. The effect of B4C addition and sintering temperature on hardnessmeasured by microhardness has been studied. Hardness of samples contain 2.0 wt% B4C was 15.10 vickers.
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