scholarly journals Fabrication of Highly Transparent Y2O3 Ceramics with CaO as Sintering Aid

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 444
Author(s):  
Danlei Yin ◽  
Jun Wang ◽  
Meng Ni ◽  
Peng Liu ◽  
Zhili Dong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Microstructure Evolution ◽  
Hot Isostatic Pressing ◽  
Optical Transmittance ◽  
Densification Rate ◽  
Vacuum Sintering ◽  
Sintering Aid ◽  
Isostatic Pressing

Highly transparent Y2O3 ceramics were successfully fabricated with CaO as sintering aid. The microstructure evolution, optical transmittance, hardness and thermal conductivity of the Y2O3 ceramics were investigated. It was found that doping a small amount (0.01–0.15 wt.%) of CaO could greatly improve the densification rate of Y2O3. With an optimized CaO dosage of 0.02 wt.% combined with the low temperature vacuum sintering plus hot isostatic pressing (HIP-ing), Y2O3 ceramics with in-line transmittance of 84.87% at 1200 nm and 81.4% at 600 nm were obtained.

Hot Isostatic Pressing to Increase Thermal Conductivity of Si3N4 Ceramics

1999 ◽  
Vol 14 (4) ◽  
pp. 1538-1541 ◽  
Author(s):  
Koji Watari ◽  
Kiyoshi Hirao ◽  
Manuel E. Brito ◽  
Motohiro Toriyama ◽  
Shuzo Kanzaki
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Hot Isostatic Pressing ◽  
Tape Casting ◽  
Crystal Defects ◽  
Nitrogen Gas ◽  
Sintering Aid ◽  
Isostatic Pressing ◽  
Seed Particles ◽  
Si3n4 Ceramics

Highly anisotropic Si3N4 ceramics were successfully fabricated by tape-casting of raw α–Si3N4 powders with β–Si3N4 single-crystal particles as seed particles and Y2O3 as an effective sintering aid, followed by hot isostatic pressing at a temperature of 2773 K for 2 h under a nitrogen gas pressure of 200 MPa. The microstructure consists of very large elongated grains (diameter ~10 μm; length of ~200 μm), highly oriented in the tape-casting direction. The thermal conductivity along this direction reaches 155 W m-1K-1 at room temperature, but varies significantly between room temperature and 1273 K. This thermal conductivity is closely related to (1) formation of extremely large elongated β–Si3N4 grains with a reduced amount of crystal defects due to the high-temperature firing and to (2) orientation of β–Si3N4 grains due to addition of seed particles and to tape-casting.

Performance of Nd-Fe-B Magnets Fabricated by Hot Isostatic Pressing and Low-Temperature Sintering

2018 ◽  
Vol 28 (1) ◽  
pp. 273-277 ◽  
Author(s):  
Fang Yang ◽  
Haiying Wang ◽  
Li You ◽  
Alex A. Volinsky ◽  
Ce Zhang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Hot Isostatic Pressing ◽  
Low Temperature Sintering ◽  
Isostatic Pressing

Microstructure and thermal conductivity of Mo–TiC cermets processed by hot isostatic pressing

2008 ◽  
Vol 380 (1-3) ◽  
pp. 85-92 ◽  
Author(s):  
Marion Le Flem ◽  
Alexandre Allemand ◽  
Stéphane Urvoy ◽  
Denis Cédat ◽  
Colette Rey
Keyword(s):  
Thermal Conductivity ◽  
Hot Isostatic Pressing ◽  
Isostatic Pressing

Optical Properties and Microstructure of Mn: MgAl2O4 Transparent Ceramic after HIP Treatment

2008 ◽  
Vol 368-372 ◽  
pp. 417-419
Author(s):  
Yue Feng Sun ◽  
Tie Cheng Lu ◽  
Xue Jun Wang ◽  
Mu Yun Lei ◽  
Cun Xin Huang
Keyword(s):  
Optical Properties ◽  
Hot Isostatic Pressing ◽  
Wavelength Region ◽  
Optical Transmittance ◽  
Light Transmittance ◽  
Transparent Ceramics ◽  
Light Wavelength ◽  
Vacuum Sintering ◽  
Two Samples ◽  
Mn Doped

5.0at% and 10.0at% Mn-doped MgAl2O4 transparent ceramics have been prepared through vacuum sintering (1750°C /2h) and subsequent hot isostatic pressing (HIP) (1650°C /2h). The effect of microstructure on the light transmittance of the sintered MgAl2O4 is discussed. Results showed that the grains became dense and grain boundary became clear and most of pores inside and between grains were removed, so the transmittance of two samples increased. The optical transmittance of the 5.0at% specimens was increased by one times in the visible light wavelength region. HIP treatment has a great effect on improving the transparency of samples with low doping concentrations.

Hot Working of Ti Aluminide Made through Reaction Synthesis

2012 ◽  
Vol 710 ◽  
pp. 137-142
Author(s):  
Rohit Kumar Gupta ◽  
Bhanu Pant ◽  
Vijaya Agarwala ◽  
Parameshwar Prasad Sinha
Keyword(s):  
Microstructure Evolution ◽  
Titanium Aluminide ◽  
Hot Isostatic Pressing ◽  
Hot Working ◽  
Reaction Synthesis ◽  
Refined Grains ◽  
Isostatic Pressing ◽  
Die Forging ◽  
Open Die Forging

Hot working of titanium aluminide made through reaction synthesis (RS) has been studied. Hot isostatic pressing under argon, isothermal pressing under vacuum, open die forging and pack forging was carried out. Hot worked billet samples were characterized for density and microstructure evolution. Presence of refined grains and dynamically recrystallized grains were observed. In case of open die forging, presence of twins was also found. From the present study, near isothermal working through near conventional processes has been confirmed. However, role of isothermal working in obtaining crack free sound deformed product has also been noted.

Mechanical properties and low-temperature aging of tetragonal zirconia polycrystals processed by hot isostatic pressing

2003 ◽  
Vol 18 (10) ◽  
pp. 2415-2426 ◽  
Author(s):  
J. Muñoz-Saldaña ◽  
H. Balmori-Ramírez ◽  
D. Jaramillo-Vigueras ◽  
T. Iga ◽  
G. A. Schneider
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Low Temperature ◽  
Hot Isostatic Pressing ◽  
Tetragonal Zirconia ◽  
Hot Water ◽  
Full Density ◽  
Isostatic Pressing ◽  
Low Temperature Aging ◽  
Temperature Aging

The influence of grain size and density of yttria-tetragonal zirconia polycrystals (Y-TZPs) ceramics on mechanical properties and on low-temperature aging degradation (LTD) in air and in hot water was investigated. A TZP powder containing 3 mol% Y2O3 was consolidated by slip casting and densified by the sintering/hot isostatic pressing (HIP) method. Only the presintered samples that contained less than 0.15% open porosity reached near full density after HIP. The best conditions to reach full density were found to be attained by presintering and HIP both at 1400 °C. At these conditions, some of the best mechanical properties such as modulus of rupture and Weibull modulus reached 1397 ± 153 MPa and, 10.6, respectively. These values were clearly higher than those obtained from sintered bodies and samples hot isostatically pressed at 1600 °C. Aging degradation of 3Y-TZP materials can be avoided through microstructural design. Fully dense materials with a critical grain size <0.36 μm did not show any evidence of degradation after extreme aging conditions at pressurized autoclaving in hot water at 100, 200, and 260 °C for 8 h. We propose a criterion to predict degradation in air as well as in hot water for the characterized materials based on the microstructure and density control of the samples.

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