Silicon nitride/boron nitride ceramic composites fabricated by reactive pressureless sintering

2009 ◽  
Vol 35 (6) ◽  
pp. 2155-2159 ◽  
Author(s):  
Bo Yuan ◽  
Ji-Xuan Liu ◽  
Guo-Jun Zhang ◽  
Yan-Mei Kan ◽  
Pei-Ling Wang
Keyword(s):  
Silicon Nitride ◽  
Boron Nitride ◽  
Ceramic Composites ◽  
Pressureless Sintering

scholarly journals Preparation and Characterization of Si3N4-BN Ceramic Composites by Gelcasting

2016 ◽  
Vol 13 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Nagaveni Thallapalli ◽  
K. Kishore Kumar ◽  
C. S. P. Rao
Keyword(s):  
Composite Material ◽  
Silicon Nitride ◽  
Boron Nitride ◽  
Aqueous Media ◽  
Ceramic Composites ◽  
Solution Ph ◽  
Gel Casting ◽  
Novel Method ◽  
Faceted Particles

In this work, a novel method for the preparation of colloids has been studied for the fabrication of silicon nitride –Boron nitride composites. In the present work, the dispersion of mixed silicon nitride –Boron nitride powders in aqueous media was studied with the changes dispersant concentration, solution pH etc. Polyethylenimine (PEI) additive as a dispersant were used for Si3N4 and BN powders in aqueous media. Well-dispersed Si3N4 and BN powders in aqueous media were attained atthe 1 wt% PEI and pH 9. 40 vol% covered Si3N4/BN slurries with varying BN content was adapted for gel casting. The gel casted material waspreheated at normal room temperature, debindered at 6000C and sintered at 17000C. The sintered composite material composed mainly of alpha-Si3N4, beta-Si3N4, and h-BN. The prepared composite material shows uniform microstructure with faceted particles, α-Si3N4 and abundant pores.

Strengthening Effect of In-Situ Dispersed Hexagonal Boron Nitride in Ceramic Composites

2006 ◽  
Vol 317-318 ◽  
pp. 163-166
Author(s):  
Guo Jun Zhang ◽  
Hideki Kita ◽  
Naoki Kondo ◽  
Tatsuki Ohji
Keyword(s):  
Grain Size ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
High Strength ◽  
Ceramic Composites ◽  
Strengthening Effect ◽  
Mechanical Shock ◽  
Metallic Particles ◽  
Reactive Hot Pressing

High strength particulate ceramic composites are in general reinforced by strong dispersoids, such as strong ceramic particles (SiC, TiB2, ZrO2, et al) and strong metallic particles (Mo, W, et al). In this work high strength ceramic composites with in-situ synthesized hexagonal boron nitride (h-BN) have been prepared and characterized. As an example, we manufactured mullite-BN composites by reactive hot pressing (RHP) using aluminum borates (9Al2O3·2B2O3 and 2Al2O3·B2O3) and silicon nitride as starting materials. The obtained material RHPed at 1800°C showed a strength of 540 MPa, which was 1.64 times higher than that of the monolithic mullite ceramics. TEM observation revealed that the composite had an isotropic microstructure with a fine mullite matrix grain size of less than 1 μm and a nano-sized h-BN platelets of about 200 nm in length and 60∼80 nm in thickness. The high strength was suggested to be from the reduced matrix grain size and the small toughening effect by the h-BN platelets. In addition, this kind of ceramic composite demonstrates low Young’s modulus that is beneficial to the thermal/mechanical shock resistance, and excellent machinability.

scholarly journals Synthesis of "in situ" reinforced silicon nitride composites

2004 ◽  
Vol 69 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Aleksandra Vuckovic ◽  
Snezana Boskovic ◽  
Ljiljana Zivkovic
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Pressureless Sintering ◽  
Sintering Additives ◽  
Sintering Time

The objective of this work was to investigate the effect of two different sintering additives (CeO2 and Y2O3 + Al2O3), sintering time and amount of ?-Si3N4 seeds on the densification, mechanical properties and microstructure of self-reinforced Si3N4 based composites obtained by pressureless sintering. Preparation of ?-Si3N4 seeds, also obtained by a pressureless sintering procedure, is described. Samples without seeds were prepared for comparison. The results imply that self-reinforced silicon nitride based composites with densities close to the theoretical values and with fracture toughness of 9.3MPa m1/2 can be obtained using a presureless sintering procedure.

Microstructure and properties of silicon nitride-matrix ceramic composites

1998 ◽  
Vol 39 (1) ◽  
pp. 22-25
Author(s):  
I. Yu. Kelina ◽  
V. A. Drobinskaya ◽  
L. A. Plyasunkova
Keyword(s):  
Silicon Nitride ◽  
Ceramic Composites ◽  
Microstructure And Properties
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