Polycrystalline boron nitride constructed from hexagonal boron nitride

RSC Advances ◽  
2014 ◽  
Vol 4 (73) ◽  
pp. 38589-38593 ◽  
Author(s):  
N. Xu ◽  
J. F. Li ◽  
B. L. Huang ◽  
B. L. Wang
Keyword(s):  
High Pressure ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Polycrystalline Structure ◽  
Shed Light

Two classes of structural families of boron nitride allotropes (named as X-BNs and L-BNs) are proposed to shed light on the polycrystalline structure of high pressure h-BN.

Tribology in Superplastic Forming Processing of 3Y-TZP/Al2O3 Ceramic at Elevated Temperatures

2007 ◽  
Vol 551-552 ◽  
pp. 507-512
Author(s):  
F. Wang ◽  
Kai Feng Zhang ◽  
Wen Bo Han
Keyword(s):  
High Pressure ◽  
Boron Nitride ◽  
Friction Factor ◽  
Elevated Temperatures ◽  
Hexagonal Boron Nitride ◽  
Superplastic Forming ◽  
Ceramic Materials ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Higher Temperature

Superplastic forming processing of ceramic materials at high temperatures and high pressure puts forward very high requests to moulds and lubricants, at which conditions seeking for appropriate lubricants is one of important preconditions in the superplastic forming of ceramic materials. Using ring compressive testing, lubricities of hexagonal boron nitride in superplastic compressive forming processing of 3Y-TZP/Al2O3 ceramic composite at elevated temperatures were investigated. Theoretical curves of friction factor were drawn according to upper bound method. Ring compressive tests were adopted at temperature of 1400 °C-1600 °C. The results indicate that when BN is used, friction factor is about 0.4, meanwhile friction factor don’t have great changes with higher temperature and increasing strain rate. X-ray diffraction shows that under high temperature and high pressure no boron nitride converts to cubic phase, which remains at room temperature.

Boron Nitride Ceramic Composite Obtained by High Pressure and High Temperature Sintering

2012 ◽  
Vol 727-728 ◽  
pp. 736-739 ◽  
Author(s):  
Ana Lucia D. Skury ◽  
Carlos A. Oliveira Monteiro ◽  
Guerold Sergueevitch Bobrovinitchii ◽  
Sérgio Neves Monteiro
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Composite Material ◽  
High Temperature ◽  
Boron Nitride ◽  
Chemical Reactions ◽  
Ceramic Composite ◽  
Sintering Process ◽  
Polycrystalline Structure ◽  
Binding Agents

In the present work, by selecting Si3N4, TiB2 and Al2O3 as binding agents as well as La3O2 as an additive, sintered wBN composites were studied. By modifying the number of sintering cycles, the composites processed at 4.5GPa and 1800°C showed improved mechanical properties. The degree of transformation of the wBN, as well as the chemical reactions during the sintering process were discussed. This new composite material was found to present polycrystalline structure that provides superior cutting properties. Moreover, owing to superior properties, the wBN composite sharpens itself during cutting.

On the choice of hexagonal boron nitride for high pressure phase transformation using the catalyst solvent process

1991 ◽  
Vol 26 (1) ◽  
pp. 196-202 ◽  
Author(s):  
M. M. Bindal ◽  
B. P. Singh ◽  
S. K. Singhal ◽  
R. K. Nayar ◽  
R. Chopra ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
High Pressure Phase ◽  
Pressure Phase

Title: Periodic Mesoporous Hexagonal Boron Nitride at High Pressure: A Route to Cubic Boron Nitride Nanocrystals and Mesoporous Cubic Boron Nitride

2017 ◽  
Vol 2 (2) ◽  
pp. 740-744 ◽  
Author(s):  
Manik Mandal ◽  
Cong Liu ◽  
Toby Sanders ◽  
Fadi Haso ◽  
Venkata Bhadram ◽  
...  
Keyword(s):  
High Pressure ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Cubic Boron Nitride
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