Microstructure and mechanical properties of h-BN/Yb4Si2O7N2 composites

Abstract

A series of h-BN based composites with Yb 4 Si 2 O 7 N 2 as a secondary phase were successfully synthesized by an in situ reaction hot pressing method. It was found that the relative density and room-temperature mechanical properties monotonically increased with increasing the content of Yb 4 Si 2 O 7 N 2 from 20 to 50 vol%. When 50 vol% Yb 4 Si 2 O 7 N 2 was introduced, the relative density of the composite reached 98.75%, and its flexural strength, compressive strength, fracture toughness, and hardness reached 338±10 MPa, 803±49 MPa, 2.06±0.06 MPa•m 1/2 , and 2.69±0.10 GPa, respectively. The strengthening effect of Yb 4 Si 2 O 7 N 2 was mainly attributed to its high modulus and high hardness. Fine microstructure was also advantageous to strength and could lead to more tortuous crack propagation paths and then improve the fracture toughness of the composites simultaneously. Meanwhile, the composites maintained good machinability.

Improvement of electric field-induced strain and energy storage density properties in lead-free BNKT-based ceramics modified by BFT doping

“…2. A similar peak slightly shied by partial substitution of Ba 2+ for [Bi 0.5 (Na 0.80 K 0.20 )] 2+ and Zr 4+ for Ti 4+ was reported by Chen et al 30 in the BNKT-BZT system. They also found that the (110) peak shied to lower 2q angles could produce an increase in the lattice constant and the unit cell dimension with increasing BZT fraction.…”

Strength Analysis of Porous YSZ Ceramics With the Same Porosity and Different Pore Structure

“…Many work has been done on the relationship between strength and structure [16][17][18][19][20][21][22][23][24]. Some empirical formulas and fracture models have been proposed.…”

Texture and Anisotropy of Hot-Pressed h-BN Matrix Composite Ceramics With in Situ Formed YAG

“…The strong sp2 covalent bonds combining B and N atoms result in a very low atomic diffusion rate even at high sintering temperatures, which makes h-BN ceramics hard to be densified during sintering [15,16] [17][18][19][20][21][22][23], has been widely proven to be an effective method to improve the sinterability of h-BN ceramics as these oxides can form liquid phases at high sintering temperatures and fill these pores between plate-like h-BN grains with the "house of cards" structure.…”