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무가압 어닐드한 SiC-TiB₂ 전도성 복합체의 특성에 미치는 In Situ YAG의 영향
辛龍德(Yong-Deok Shin),朱陳榮(Jin-Young Ju),高台憲(Tae-Hun Ko) 대한전기학회 2008 전기학회논문지 Vol.57 No.5
The composites were fabricated 61[vol.%] β-SiC and 39[vol.%] TiB₂ powders with the liquid forming additives of 8, 12, 16[wt%] Al₂O₃+Y₂O₃ as a sintering aid by pressureless annealing at 1650[℃] for 4 hours. The present study investigated the influence of the content of Al₂O₃+Y₂O₃ sintering additives on the microstructure, mechanical and electrical properties of the pressureless annealed SiC-TiB₂ electroconductive ceramic composites. Reactions between SiC and transition metal TiB₂ were not observed in the microstructure and the phase analysis of the pressureless annealed SiC-TiB₂ electroconductive ceramic composites. Phase analysis of SiC-TiB₂ composites by XRD revealed mostly of α -SiC(6H), β-SiC(3C), TiB₂, and In Situ YAG(Al?Y₃O₁₂). The relative density of SiC-TiB₂ composites was lowered due to gaseous products of the result of reaction between SiC and Al₂O₃+ Y₂O₃. There is another reason which pressureless annealed temperature 1650[℃] is lower 300-450[℃] than applied pressure sintering temperature 1950-2100[℃]. The relative density, the flexural strength, the Young's modulus and the Vicker's hardness showed the highest value of 82.29[%], 189.5[Mpa], 54.60[Gpa] and 2.84[Gpa] for SiC-TiB₂ composites added with 16[wt%] Al₂O₃+Y₂O₃ additives at room temperature. Abnormal grain growth takes place during phase transformation from β-SiC into α-SiC was correlated with In Situ YAG phase by reaction between Al₂O₃ and Y₂O₃ additive during sintering. The electrical resistivity showed the lowest value of 0.0117[Ω. ㎝] for 16[wt%] Al₂O₃+Y₂O₃ additives at 25[℃]. The electrical resistivity was all negative temperature coefficient resistance (NTCR) in the temperature ranges from 25℃ to 700[℃]. The resistance temperature coefficient of composite showed the lowest value of -2.3×10?³[℃]?¹ for 16[wt%] additives in the temperature ranges from 25[℃] to 100[℃].
常壓燒結한 SiC-ZrB₂ 電導性 複合體의 特性에 미치는 In Situ YAG의 影響
辛龍德(Yong-Deok Shin),朱陣榮(Jin-Young Ju),高台憲(Tae-Hun Ko),李政勳(Jung-Hoon Lee) 대한전기학회 2008 전기학회논문지 Vol.57 No.11
The effect of content of Al₂O₃+Y₂O₃ sintering additives on the densification behavior, mechanical and electrical properties of the pressureless-sintered SiC-ZrB₂ electroconductive ceramic composites was investigated. The SiC-ZrB₂ electroconductive ceramic composites were pressurless-sintered for 2 hours at 1,700[℃] temperatures with an addition of Al₂O₃+Y₂O₃(6 : 4 mixture of Al₂O₃ and Y₂O₃) as a sintering aid in the range of 8 ~ 20[wt%]. Phase analysis of SiC-ZrB₂ composites by XRD revealed mostly of α-SiC(6H), ZrB₂ and In Situ YAG(A1?Y₃O₁₂). The relative density, flexural strength, Young's modulus and vicker's hardness showed the highest value of 89.02[%], 81.58[㎫], 31.44[㎬] and l.34[㎬] for SiC-ZrB₂ composites added with 16[wt%] Al₂O₃+Y₂O₃ additives at room temperature respectively. Abnormal grain growth takes place during phase transformation from β-SiC into α-SiC was correlated with In Situ YAG phase by reaction between Al₂O₃ and Y₂O₃ additive during sintering. The electrical resistivity showed the lowest value of 3.14×10?²Ωㆍ㎝ for SiC-ZrB₂ composite added with 16[wt%] Al₂O₃+Y₂O₃ additives at 700[℃]. The electrical resistivity of the SiC-TiB₂ and SiC-ZrB₂ composite was all negative temperature coefficient resistance (NTCR) in the temperature ranges from room temperature to 700[℃]. Compositional design and optimization of processing parameters are key factors for controlling and improving the properties of SiC-based electroconductive ceramic composites.
液狀燒結한 SiC系의 傳導性 複合體의 微細構造와 特性에 미치는 Boride의 影響
辛龍德(Yong-Deok Shin),朱陳榮(Jin-Young Ju),高台憲(Tae-Hun Ko) 대한전기학회 2007 전기학회논문지 Vol.56 No.9
The composites were fabricated. respectively, using 61[vol.%] SiC-39[vol.%] TiB₂ and using 61[vol.%] SiC-39[vol.%] ZrB₂ powders with the liquid forming additives of 12[wt%] Al₂O₃+ Y₂O₃ by hot pressing annealing at 1650 [℃] for 4 hours. Reactions between SiC and transition metal TiB₂. ZrB₂ were not observed in this microstructure. The result of phase analysis of composites by XRD revealed SiC(6H. 3C), TiB₂; ZrB₂ and YAG(Al?Y₃O₁₂) crystal phase on the Liquid-Phase-Sintered(LPS) SiC-TiB₂. and SiC-ZrB₂ composite. β→a-SiC phase transformation was occurred on the SiC-TiB₂ and SiC-ZrB₂ composite. The relative density, the flexural strength and Young's modulus showed the highest value of 98.57[%], 249.42[㎫] and 91.64[㎬] in SiC-ZrB₂ composite at room temperature respectively. The electrical resistivity showed the lowest value of 7.96×10?⁴[Ωㆍ㎝] for SiC-ZrB₂ composite at 25[℃], The electrical resistivity of the SiC-TiB₂ and SiC-ZrB₂ composite was all positive temperature coefficient resistance (PTCR) in the temperature ranges from 25[℃] to 700[℃]. The resistance temperature coefficient of composite showed the lowest value of 1.319×10?³/[℃] for SiC-ZrB₂ composite in the temperature ranges from l00[℃] to 300[℃]. Compositional design and optimization of processing parameters are key factors for controlling and improving the properties of SiC-based electroconductive ceramic composites.
자기 통전식 SiC 세라믹 발열체 개발을 위한 기초 특성 연구
신용덕(Yong-Deok Shin),고태헌(Tae-Hun Ko),주진영(Jin-Young Ju) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.11
The composites were fabricated β-SiC and TiB₂ powders with the liquid forming additives of 8, 12, 16[wt%] Al₂O₃+Y₂O₃ as a sintering aid by pressureless annealing at 1,650[℃] for 4 hours. Reactions between SiC and transition metal TiB₂ were not observed in the microstructure and the phase analysis of the pressureless annealed SiC-TiB₂ electroconductive ceramic composites. The relative density, the flexural strength, the Young's modulus and the Vicker's hardness showed the highest value of 82.29[%], 189.5[㎫], 54.60[㎬] and 2.84[㎬] for SiC-TiB₂ composites added with 16[wt%] Al₂O₃+Y₂O₃ additives at room temperature. The relative density of SiC-TiB₂ composites was lowered due to gaseous products of the result of reaction between SiC and Al₂O₃+Y₂O₃. The electrical resistivity showed the lowest value of 0.012[Ω · ㎝] for 16[wt%] at 25[℃]. The electrical resistivity was all negative temperature coefficient resistance (NTCR) in the temperature ranges from 25[℃] to 700[℃].