Microstructure and tribological properties of pulsed electric current sintered alumina–zirconia nanocomposites with different solid lubricants

Abstract Dense Al 2 O 3 -15 wt% (ZrO 2 -3 mol%Y 2 O 3 ) nanocomposites modified with 3 wt% of self-lubricating component (CaF 2 , BaF 2 , MoS 2 , WS 2 , h-BN, or graphite) were consolidated by pulsed electric current sintering. Their microstructure as well as mechanical and tribological properties were evaluated. During consolidation composition of the self-lubricating components was conserved except for BaF 2 , which partially melted. The Al 2 O 3 /ZrO 2 (3 mol%Y 2 O 3 ) matrix showed hardness of 20.35 GPa and Young’s modulus of 320 GPa determined by Vickers indentation. All solid lubricant additives led to a decrease in hardness of the composite. Solid lubricant additives lowered the coefficient of friction (CoF) against alumina at room temperature. In pin-on-disc tests CoF of 0.38–0.42 was measured for all the materials against alumina ball. The lowest CoF of 0.043 was measured for Al 2 O 3 /ZrO 2 (3 mol%Y 2 O 3 )/CaF 2 in the scratch test against diamond stylus while the matrix material showed lower friction than other materials. The measured wear rates were in the order of 10 −12 for Al 2 O 3 /ZrO 2 (3 mol%Y 2 O 3 )/CaF 2 , Al 2 O 3 /ZrO 2 (3 mol%Y 2 O 3 )/MoS 2 , and Al 2 O 3 /ZrO 2 (3 mol%Y 2 O 3 )/WS 2 .