Effect of welding speed on mechanical strength of friction welded joint of YSZ–alumina composite and 6061 aluminum alloy

Successful application of ceramics in many devices and structures requires some type of ceramic metal joining. All applications require a high-strength metal–ceramic bond. Even successful joint formation does not guarantee mechanical soundness of the joint. The inherent differences in physical properties between the ceramic and the metal make it extremely difficult to find an effective joining process that maintains the strength and resilience of the overall joint. However, friction welding, which is a type of easy manufacturing method, is one of the methods that have been widely used for many products. It is one of the most simple, economical and highly productive methods in joining similar and dissimilar metals. In the present study, a ceramic composite of YSZ–Al2O3 was friction welded to 6061 Al alloy. Alumina rods containing 0 and 25 wt% yttria stabilized zirconia were fabricated by slip casting process and subsequently sintered at 1600 °C. The diameter of both the ceramic and metal rods was 16 mm. Rotational speeds for friction welding were between 630 and 2500 rpm. A friction pressure was maintained at 7 MPa and friction time was kept constant. The mechanical strength of the friction welded Al2O3–YSZ to 6061 alloy was determined with a four-point bend test and fracture failure surfaces. The experimental results indicated that the mechanical strength of friction-welded ceramic composite/6061 Al alloy components was observably affected by joining at the different rotational speeds selected. The fracture surface was observed to be different for ductile and brittle failure.