Journals / İTÜ Dergisi Seri D: Mühendislik / 2004 / Cilt: 3 - Sayı: 1
The microstructure effects on fracture toughness of pressureless sintered silicon carbide
- Pages
- 98–104
- DOI
- —
Abstract
In this study, eight group silicon carbide compositions were prepared and pressed using by uni-axially and cold isostatically pressing techniques. Green density has been observed for the pressed sample and Pyrolysing process is used as pro-process for carbonizing the Phenolic resins. Phenolic resins have been used to avoid the decomposition of silicon carbide and stabilize the structure. Solid state and liquid phase sintering techniques have been used for the sintering. Temperature and time are used as sintering parameters. Densities and porosity have been measured by Archimedes method and fracture toughness have been tested by indentation fracture toughness. CAB12 Coded composition (B4C + Al2O3+Y2O3 + carbon) sintered at 2150 °C. The density of samples has been measured as 3.02 gr/cm3 indentation fracture toughness were obtained 4.57 $MPa.m^{1/2}$ after sintering. CAJ09 Coded composition (HP1 SiC + Al2O3 + Y2O3 + carbon additives) has been sintered at 2000 °C. The density of sintered samples was measured as 3.12 gr/cm and 4,39 $MPa.m^{1/2}$ indentation fracture toughness values were obtained after sintering. Al2O3 and Y2O3 reaction resulted in a phase being Y5Al3 observed by XRD analysis. CAK01- CAK07 Coded compositions (#70 SiC + HP1 SiC + Al2O3 + Y2O3 + carbon additive) has been sintered at 2000 °C. The density of sintered samples was measured as 2.48 - 2.62 gr/cm3. Fracture toughness cannot be measured due to the 20.61 - 24.76 % porosity of the sample. Al2O3 and Y2O3 reaction resulted in a phase being Al5.Y3.O12 observed by XRD analysis. The obtained results have been observed in a good harmony compared to literature survey.
Özet
Bu çalışmada, farklı içerikte SiC karışımlar hazırlanmış, tek yönlü ve soğuk izostatik presleme tekniği ile preslenmelerdir. Şekillendirilen numunelerin yaş yoğunlukları tespit edilmiş, piroliz işlemi silisyum karbür numunelerde sinterleme öncesi ara işlem olarak kullanılmıştır. Numuneler, katı - katı ve katı - sıvı difüzyonu tekniği ile açık atmosfer ve argon gaz atmosferinde farklı sıcaklık ve sürelerde sinterlenerek üretilmişlerdir. Elde edilen numunelerin sinterleme sonrasında sahip oldukları, parazite, yoğunluk, sinterleme küçülmesi, sertlik ve kırılma tokluğu ölçümleri yapılmıştır. Elde edilen sonuçların literatürde verilen değerlerle uyum içinde olduğu belirlenmiştir