Loading...
Investigation of the structural and mechanical properties of micro-/nano-sized Al2O3 and cBN composites prepared by spark plasma sintering
Irshad, H.M. Ahmed, B.A. Ehsan, M.A. Khan, Tahir I. Laoui, T. Yousaf, M.R. Ibrahim, A. Hakeem, A.S.
Irshad, H.M.
Ahmed, B.A.
Ehsan, M.A.
Khan, Tahir I.
Laoui, T.
Yousaf, M.R.
Ibrahim, A.
Hakeem, A.S.
Publication Date
2017-10
End of Embargo
Supervisor
Rights
Peer-Reviewed
Yes
Open Access status
Accepted for publication
2017-05-26
Institution
Department
Awarded
Embargo end date
Additional title
Abstract
Alumina-cubic boron nitride (cBN) composites were prepared using the spark plasma sintering (SPS) technique. Alpha-alumina powders with particle sizes of ∼15 µm and ∼150 nm were used as the matrix while cBN particles with and without nickel coating were used as reinforcement agents. The amount of both coated and uncoated cBN reinforcements for each type of matrix was varied between 10 to 30 wt%. The powder materials were sintered at a temperature of 1400 °C under a constant uniaxial pressure of 50 MPa. We studied the effect of the size of the starting alumina powder particles, as well as the effect of the nickel coating, on the phase transformation from cBN to hBN (hexagonal boron nitride) and on the thermo-mechanical properties of the composites. In contrast to micro-sized alumina, utilization of nano-sized alumina as the starting powder was observed to have played a pivotal role in preventing the cBN-to-hBN transformation. The composites prepared using nano-sized alumina reinforced with nickel-coated 30 wt% cBN showed the highest relative density of 99% along with the highest Vickers hardness (Hv2) value of 29 GPa. Because the compositions made with micro-sized alumina underwent the phase transformation from cBN to hBN, their relative densification as well as hardness values were relatively low (20.9–22.8 GPa). However, the nickel coating on the cBN reinforcement particles hindered the cBN-to-hBN transformation in the micro-sized alumina matrix, resulting in improved hardness values of up to 24.64 GPa.
Version
Accepted Manuscript
Citation
Irshad HM, Ahmed BA, Ehsan MA et al (2017) Investigation of the structural and mechanical properties of micro-/nano-sized Al2O3 and cBN composites prepared by spark plasma sintering. Ceramics International. 43(14): 10645-10653.
Link to publisher’s version
Link to published version
Link to Version of Record
Type
Article