The Effect Of Interface Improvement On The Mechanical Properties Of A1 ₂ O _3P / Steel Matrix Composites

Due to the poor wettability between Al2O3 particles and liquid steel, in general the interface binding of Al2O3P/1065 steel composites combine is mechanical bond which result the poor mechanical properties of the composites. To promote the interfacial bond between Al2O3 particles and steel, and improve the mechanical properties of the composites, the activating substance Ni, Mn, Co, and ZrO2 powders were add into the perform and then preparated the Al2O3P/1065 steel composites.The Al2O3p/1065 steel composites which containing the activating substance Ni, Mn, Co, and ZrO2, respectively, had been fabricated by squeeze casting. The interface bonding strength, hardness and three-point bending strength were tested and the matrix and interface structure were researched. Finally, a harrowing tooth which composed by Ni activated Al2O3P/1065 steel composites was preparated by squeeze casting method successfully.To characterize the interface bonding strength of Al2O3p/1065 steel composite, this paper tested the shear strength of the composites which formed by Al2O3 ceramic pieces and 1065 steel. The results showed that by adding the Ni, Mn and ZrO2 powder into the perform, respectively, the interface bonding strength was 5.33MPa,3.31MPa and 4.54MPa, compared with that without activating substance composites increased 89.7%,17.8% and 61.6%. The interface bonding strength of the composite containing Co has not been improved, which was only 2.39MPa.The matrix structure of the composite containing Ni is pearlite, SEM photographs could not find an interface layer formed. The XRD analysis showed that the phases of the composite are Fe, Al2O3, AlNi, (Fe, Ni) and NiO, Ni may reacted with Al2O3 and generated NiO and AlNi. The presence of the interface product AlNi improved the interface binding strength. Hardness and bending strength of the composite were 43.3HRC and 695.04MPa, respectively.The matrix structure of the composite containing Mn is pearlite and ferrite, an interface layer can be found by SEM photograph. The XRD analysis showed that the phases of the composite are Fe, Al2O3 and Mn, so Mn did not react with Al2O3. Hardness and bending strength of the composite were 49HRC and 516.43MPa, respectively.The matrix structure of the composite containing Co is pearlite and ferrite, an interface layer can be found by SEM photograph. The XRD analysis showed that the phases of composite are only Fe and Al2O3. Hardness and bending strength of the composite were 41.5HRC and 486.34MPa, respectively.The matrix structure of the composite containing ZrO2 is pearlite and ferrite, an interface layer can be found by SEM photograph. The XRD analysis showed that the phases of the composite are only Fe, Al2O3 and ZrO2, ZrO2 was formed the interface layer instead of react with Al2O3. Hardness and bending strength of the composite were 44.8HRC and 733.23MPa, respectively.The mechanical properties of composite depend on the properties of the matrix and the interfacial bonding strength. By adding the Ni and ZrO2 powder into the perform, the interface bonding strength has been improved on the basis of maintaining the properties of the matrix, so the mechanical properties (hardness, bending strength) of composites are greatly improved.