Microstructure and mechanical properties of AlN–hBN based machinable ceramics prepared by pressureless sintering

Anisotropy of elastic properties and thermal conductivity of Al2O3/h-BN composites

“…In addition, Broniszewski et al [18] used an attritor-type mill for homogenization, which resulted with good deagglomeration effect for small solid lubricate content (as in the case of this study), but they did not mentioned about h-BN quantities higher than 10 vol.%. Cho et al [22] noticed the formation of high porosity BN pockets in sintered bodies of AlN-hBN composites, where the starting powders were mixed with the use of simple ball milling method. They connected this effect for example with significant decrease of bending strength for higher h-BN content.…”

Spark plasma sintering of TiN–TiB2–hBN composites and their properties

“…The relative density of B 4 ChBN prepared by the same group decreased from 99% to 92% as the hBN content increased from 0 to 37.5 vol% [20]. Additives such as Y 2 O 3 and Al 2 O 3 have been added in the sintering processes of AlN-hBN [10,11] and Si 3 N 3 -hBN [7]. The TiNTiB 2 -hBN composites in the present study were prepared at a lower temperature (i.e.…”

“…At 2073 K, TiN slightly reacts with hBN, forming a small amount of TiB 2 in hBN-TiN composites [18]. To avoid this reaction, the TiN-TiB 2 -hBN composites were sintered at 1973 K. two methods; pressureless sintering [11] and hot pressing [10]. As the hBN content increased from 0 to 30 vol%, the relative density of their AlN-hBN composites prepared by pressureless sintering decreased from 99% to 86% [11], while that of composites prepared by hot pressing remained high (i.e.…”

“…This configuration confers anisotropic mechanical and thermal properties. hBN addition is widely reported to improve the mechanical and thermal properties of composite materials [6][7][8][9][10][11][12][13]. Sun et al reported that the highest flexural strength of Si 3 N 4 -hBN composite is 650 MPa at 4 vol% hBN, while the fracture toughness decreases from 10.5 to 7.0 MPa m 1/2 as the hBN content increases from 0 to 8 vol% [8].…”

“…Sun et al reported that the highest flexural strength of Si 3 N 4 -hBN composite is 650 MPa at 4 vol% hBN, while the fracture toughness decreases from 10.5 to 7.0 MPa m 1/2 as the hBN content increases from 0 to 8 vol% [8]. Cho et al reported that the hardness of AlN-hBN composites decreases from 13.7 to 2.9 GPa as the hBN content increases from 0 to 15 vol%, whereas the fracture toughness (3 MPa m 1/2 ) is independent of hBN content [11]. Gouriot-Launay et al increased the hBN content of Al 2 O 3 -AlON-hBN composites from 0 to 30 vol% and reported that thermal shock resistance increases with increasing hBN content, while the maximum flexural strength (530 MPa) is achieved at 10 vol% hBN [12].…”