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Al-Amin Md.,Mumu Homayra Tabassum,Sarker Saugata,Alam Md. Zahangir,Gafur M. A. 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.1
The effects of sintering temperature and ZrO2 addition on the hardness and fracture toughness of zirconia toughened alumina (ZTA)–MgO–TiO2 composite was investigated. 5 wt.% CeO2 was added to ZTA containing 5 wt.% of MgO and 5 wt.% of TiO2. Two sets of composition A5ZMTC and A15ZMTC were used consisting of 5 wt.% and 15 wt.% of 3YSZ, respectively, to analyze the effect of CeO2 on the base composition. The powders were pressed into pellets and sintered at different temperatures of 1450 °C, 1500 °C, 1600 °C and 1650 °C for 3 h. Density, hardness and fracture toughness increased to a maximum value and then decreased. From the XRD analysis, Ce0.7Zr0.3O2 in only A5ZMTC and CeAl11O18 in only A15ZMTC are evident. The highest fracture toughness of 12.03 MPam1/2 (Casellas) was achieved at 1500 °C in A15ZMTC and maximum hardness of 14.15 GPa was obtained in A5ZMTC sintered at 1450 °C.
Taimur-Al-Mobarak,M. F. Mina,M. A. Gafur,A. N. Ahmed,S. A. Dhar 한국섬유공학회 2018 Fibers and polymers Vol.19 No.1
Sponge-gourd (SG) natural fibers obtained from Luffa cylindrica plant were chemically treated separately using alkali (5, 10, and 15 wt%), acetic anhydride (5, 10, and 15 wt%), and benzoyl chloride (5, 10, and 15 wt%). Both untreated and chemically treated SG fibers (SGFs) were subsequently characterized using a field emission scanning electronmicroscope, a Fourier transform infrared spectrometer, an X-ray diffractometer, a universal testing machine, and a thermogravimetric analyzer. Surface analysis by scanning electron microscopy shows that the alkali treatments promote better outer surface layer than other treatments of the SGF with the exposition of inner fibrillar structure, thereby increasing roughness of the fiber surface. Alkali treatment also improves the crystallinity and exhibits new chemical bond formation inthe SGF. The tensile strength and Young’s modulus have been analyzed through a two-parameter Weibull distribution model, where a significant increase in mechanical property of benzoylated fibers has been observed. The thermal stability of the modified fibers is also found to increase by acetic anhydride treatment.