Ablation Resistant of Pressureless Sintered ZrB2-Based Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 199-202 ◽  
Author(s):  
Chang Ling Zhou ◽  
Yan Yan Wang ◽  
Zhi Qiang Cheng ◽  
Chong Hai Wang ◽  
Jie Fan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Energy Dispersive Spectrometry ◽  
Argon Atmosphere ◽  
Pressureless Sintering ◽  
Ultra High Temperature Ceramics ◽  
Ablation Resistance ◽  
Linear Ablation ◽  
Scanning Electron ◽  
Ultra High Temperature

ZrB2-SiC and ZrB2-SiC-C ultra-high temperature ceramics (UHTCs) were fabricated by pressureless sintering under an argon atmosphere. The mass and linear ablation rates were tested in an oxyacetylene flame with high velocity. The microstructure and phase transformation of the ZrB2-based UHTCs were characterized by scanning electron microscopy along with energy dispersive spectrometry. Results show that the UHTCs have excellent properties of ablation resistance at ultra-high temperature. The values of mass and linear ablation rates were lower in the ZrB2-SiC UHTCs than those measured for ZrB2-SiC-C. The effect of C addition on the ablation resistant was not obvious but it influenced the microstructure of the ZrB2-SiC UHTCs. And the ablation resistant mechanisms of ZrB2-based UHTCs were discussed according to microstructure analysis.

Pressureless Sintering of ZrB2 with β-SiC Addition

2015 ◽  
Vol 820 ◽  
pp. 250-255 ◽  
Author(s):  
Mariah Oliveira Juliani ◽  
Carolyne Davi Oliveria ◽  
Rosa Maria Rocha
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Zirconium Diboride ◽  
Theoretical Density ◽  
Pressureless Sintering ◽  
Ultra High Temperature Ceramics ◽  
Ultra High Temperature

Zirconium diboride (ZrB2) is a covalent compound that leads the category of ultra high temperature ceramics materials owing to its unique properties. In this work, the effect of addition of beta-silicon carbide (β-SiC) in pressureless sintering of ZrB2 was investigated. Four compositions were prepared with 0, 10, 20 e 30 vol% of SiC. ZrB2 powder and mixtures were prepared in by planetary milling with SiC spheres at 4 h. Two sintering temperatures were used, one at 2050 oC/1h and other at 2150 °C/1h. The addition of SiC has promoted an increasing in densification with the increasing of SiC content. The total densification of sample sintered at 2050 oC was 90% of theoretical density for sample with 30 vol% of SiC, while the maximum densification for temperature of 2150 oC was 91,0 %TD.

Pressureless Sintering of Ultra-High Temperature ZrB2-SiC Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 1746-1749 ◽  
Author(s):  
Zhi Qiang Cheng ◽  
Chang Ling Zhou ◽  
Ting Yan Tian ◽  
Cheng Gong Sun ◽  
Zhi Hong Shi ◽  
...  
Keyword(s):  
High Temperature ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Ablation Rate ◽  
Ultra High Temperature Ceramics ◽  
Sintering Additive ◽  
Sic Ceramics ◽  
Ablation Resistance ◽  
Sic Ceramic ◽  
Ultra High Temperature

ZrB2-SiC ultra-high temperature ceramics (UHTCs) were pressureless sintered with Y2O3-Al2O3 as the sintering additives. The effects of sintering additive and crystallization annealing on the microstructure and properties of ZrB2-SiC UHTCs were investigated. Sintering was activated by producing liquid phase of Y2O3 and Al2O3. The relative density of sintered ZrB2-20wt%SiC ceramic could reach 96% when the content of sintering additive was 6% and the sintering temperature was 1750°C and its bending strength, Vickers hardness, and fracture toughness were 412 MPa, 13 GPa, and 6.0 MPa•m1/2, respectively. The crystallization annealing can result in YAG phase from grain boundary and enhance the high temperature properties of the UHTCs. The UHTCs have excellent ablation resistance at ultra-high temperatures, and a very low ablation rate of 0.0006 mm/s after ablation for 900s at 2800°C.

scholarly journals Advances in ultra-high temperature ceramics, composites, and coatings

2021 ◽  
Vol 11 (1) ◽  
pp. 1-56
Author(s):  
Dewei Ni ◽  
Yuan Cheng ◽  
Jiaping Zhang ◽  
Ji-Xuan Liu ◽  
Ji Zou ◽  
...  
Keyword(s):  
High Temperature ◽  
Elevated Temperatures ◽  
Future Directions ◽  
Ultra High Temperature Ceramics ◽  
High Temperature Materials ◽  
Ablation Resistance ◽  
Structural Applications ◽  
Shock Resistance ◽  
Engine Components ◽  
Ultra High Temperature

AbstractUltra-high temperature ceramics (UHTCs) are generally referred to the carbides, nitrides, and borides of the transition metals, with the Group IVB compounds (Zr & Hf) and TaC as the main focus. The UHTCs are endowed with ultra-high melting points, excellent mechanical properties, and ablation resistance at elevated temperatures. These unique combinations of properties make them promising materials for extremely environmental structural applications in rocket and hypersonic vehicles, particularly nozzles, leading edges, and engine components, etc. In addition to bulk UHTCs, UHTC coatings and fiber reinforced UHTC composites are extensively developed and applied to avoid the intrinsic brittleness and poor thermal shock resistance of bulk ceramics. Recently, highentropy UHTCs are developed rapidly and attract a lot of attention as an emerging direction for ultra-high temperature materials. This review presents the state of the art of processing approaches, microstructure design and properties of UHTCs from bulk materials to composites and coatings, as well as the future directions.

Synthesize Ti3SiC2 from TiH2 by Pressureless Sintering

2012 ◽  
Vol 512-515 ◽  
pp. 676-680 ◽  
Author(s):  
Liang Li ◽  
Ai Guo Zhou ◽  
Li Bo Wang ◽  
Fei Xiang Hu
Keyword(s):  
Electron Microscopy ◽  
Single Phase ◽  
Argon Atmosphere ◽  
Pressureless Sintering ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
Titanium Silicon Carbide ◽  
X Ray ◽  
Titanium Silicon ◽  
Scanning Electron

In this paper, titanium silicon carbide (Ti3SiC2) powders were synthesized from TiH2 as Ti source by pressureless sintering in flowing argon atmosphere without preliminary dehydrogenation. Starting materials are powder mixtures with the mole ratio of 3TiH2/Si/2C or 3TiH2/SiC/C. Both kinds of starting materials were sintered in a tube furnace at the temperature range from 1300°C to 1500°C for 10~180min in flowing argon atmosphere. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the phase compositions and morphology of the products after different treatments. It was showed that almost single phase Ti3SiC2 powder (94.7 wt.%) can be synthesized by pressureless sintering from 3TiH2/Si/2C powders at 1400~1425°C for about 180min or from 3TiH2/SiC/C powders at 1425~1500°C for about 180min. From SEM micrographs, as-synthesized samples were porous. Most plate-like grains were about 5~10 μm in diameter and 1~2 μm in thickness. The speed of temperature increasing is an important factor to affect the purity of as-synthesized Ti3SiC2.

scholarly journals Analytical study of Buddha sculptures in Jingyin temple of Taiyuan, China

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Xiaojian Bai ◽  
Chen Jia ◽  
Zhigen Chen ◽  
Yuxuan Gong ◽  
Huwei Cheng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Analytical Study ◽  
Energy Dispersive Spectrometry ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Ancient China ◽  
X Ray ◽  
Unique Style ◽  
Scanning Electron

AbstractWith exquisite design and unique style, the painted sculptures of Tutang Buddha and two attendants Buddha in Jingyin Temple are precious cultural heritages of China. The sculpture of Tutang Buddha, which was carved from a mound and painted by ancient craftsmen, was rarely found in ancient China. However, due to natural and human factors, the sculptures were severely damaged. Obviously, they require urgent and appropriate protection and restoration. In this study, samples taken from the sculptures were analysed through multiple analytical techniques, including scanning electron microscopy with energy dispersive spectrometry (SEM–EDS), Raman spectroscopy, X-ray diffraction (XRD), optical microscopy (OM) and granulometry. The analysis results enable us to infer the techniques used by the craftsmen in making the sculptures and provide a reliable evidence for the conservation and future protection of these and similar sculptures.

Sign in / Sign up

Export Citation Format

Share Document