Densification and Mechanical Properties of B₄C with Al₂O₃ as a Sintering Aid

Abstract

The densification behavior and mechanical properties of B 4 C hot-pressed at 2000°C for 1 h with additions of Al 2 O 3 up to 10 vol% were investigated. Sinterability was greatly improved by the addition of a small amount of Al 2 O 3 . The improvement was attributed to the enhanced mobility of elements through the Al 2 O 3 near the melting temperature or a reaction product formed at the grain boundaries. As a result of this improvement in the density, mechanical properties, such as hardness, elastic modulus, strength, and fracture toughness, increased remarkably. However, when the amount of Al 2 O 3 exceeded 5 vol%, the level of improvement in the mechanical properties, except for fracture toughness, was reduced presumably because of the high thermal mismatch between B 4 C and Al 2 O 3 .

Investigation on Addition of Kaolinite on Sintering Behavior and Mechanical Properties of B4C

“…It is suggested that the lower hardness of the samples having higher amount of kaolinite is related to higher amount of Al 2 O 3 and MgB 2 in such samples. The effect of density on improvement of mechanical properties has been reported by Kim for B 4 C samples having 5 wt.% alumina [19].…”

“…3b and 4b), which is due to enhanced mass transport within these phases or reaction products at the grain boundaries. This improves such properties as hardness and fracture toughness (Ref 19). The effect of kaolinite addition on relative density of the samples sintered at 2050 and 2150°C as a function of kaolinite percentage is shown in Fig.…”

Moagem de pós de carbeto de silício em moinho planetário

“…A separação do SiC dos demais elementos, sob a pura ótica de análise de moagem, a qual pode ser feita através de decantação, seria muito interessante para que a eficiência do processo pudesse ser avaliada com parâmetros reais. Do ponto de vista de efeito da alteração química sobre a sinterabilidade do SiC, cabe citar que a presença de aditivos pode beneficiar o processo de sinterização, sendo o caso mais típico a adição de carbono e boro na sinterização do SiC [20][21][22] e de ZrO 2 melhorando a sinterabilidade do B 4 C através da formação de ZrB [23]. Como os trabalhos termodinâmicos de Negita [24] colocam a ZrO 2 próximo ao campo de sinterabilidade do SiC e como não foi encontrado na literatura situação similar a esta, procedeu-se os estudos de sinterabilidade e tenacidade à fratura dos presentes materiais.…”

Processing and Mechanical Properties of Boron Carbide–Titanium Diboride Ceramic Matrix Composites

“…In other words, B 4 C reacts with other oxides during sintering to form new compounds that might be detrimental to the unique properties of B 4 C. However, it has been observed that the addition of small amounts of Al 2 O 3 can increase the sinterability of B 4 C remarkably [21]. In addition to the increases in density, the mechanical properties, such as hardness, flexural strength, and fracture toughness, were also improved significantly.…”