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.

EFFECTS OF THERMAL ENVIRONMENTS ON THE THERMAL SHOCK RESISTANCE OF ULTRA-HIGH TEMPERATURE CERAMICS

2008 ◽  
Vol 22 (14) ◽  
pp. 1375-1380 ◽  
Author(s):  
WEIGUO LI ◽  
DAINING FANG
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Thermal Environment ◽  
Transfer Condition ◽  
Ultra High Temperature Ceramics ◽  
Thermal Environments ◽  
Shock Resistance ◽  
Ultra High Temperature

In the present study, the temperature-dependent thermal shock resistance parameter of Ultra-High Temperature Ceramics (UHTCs) was measured based on the current evaluation theories of thermal shock resistance parameters, since the material parameters of UHTCs are very sensitive to the changes of temperature. The influence of some important thermal environment parameters on the thermal shock resistance and critical temperature difference of rupture of UHTCs were studied. By establishing the relation between the temperature and the thermal or mechanical properties of the UHTCs, we found that thermal shock behavior of UHTCs is strongly affected by the surface heat transfer coefficient, heat transfer condition and initial temperature of the thermal shock.

Processing Methods for Ultra High Temperature Ceramics

2013 ◽  
pp. 180-202 ◽  
Author(s):  
J.K. Sonber ◽  
T.S.R. Ch. Murthy ◽  
C. Subramanian ◽  
R.C. Hubli ◽  
A.K. Suri
Keyword(s):  
High Temperature ◽  
Elevated Temperatures ◽  
Thermal Protection ◽  
Leading Edge ◽  
Powder Synthesis ◽  
Ultra High Temperature Ceramics ◽  
Sharp Edges ◽  
The Stability ◽  
Intense Heat ◽  
Ultra High Temperature

Ultra-high-temperature ceramics (UHTCs) are a group of materials that can withstand ultra high temperatures (1600-3000 oC) which will be encountered by future hypersonic re-entry vehicles. Future re-entry vehicles will have sharp edges to improve flight performance. The sharp leading edges result in higher surface temperature than that of the actual blunt edged vehicles that could not be withstood by the conventional thermal protection system materials. To withstand the intense heat generated when these vehicles dip in and out of the upper atmosphere, UHTC materials are needed. UHTC materials are composed of borides of early transition metals. From the larger list of borides, ZrB2 and HfB2 have received the most attention as potential candidates for leading edge materials because their oxidation resistance is superior to that of other borides due to the stability of the ZrO2 and HfO2 scales that form on these materials at elevated temperatures in oxidizing environments. Processing of these materials is very difficult as these materials are very refractory in nature. In this chapter, processes available for powder synthesis, fabrication of dense bodies, and coating processes is discussed.

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.

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