Friction Welding of 6061 Aluminum Alloy with YSZ-Alumina Composite for Improved Mechanical and Thermal Properties
In the present work, three main dissimilar materials were used in friction welding i.e. 6061 aluminum alloy joined to pure alumina, alumina-25 wt. % YSZ and alumina-50 wt. % YSZ. The ceramic systems were fabricated by slip casting and subsequently sintered at 1600 ºC, while the metal aluminum alloy...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2013
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| Subjects: | |
| Online Access: | http://eprints.usm.my/41109/1/UDAY_M._BASHEER_24_Pages.pdf http://eprints.usm.my/41109/ |
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| Institution: | Universiti Sains Malaysia |
| Language: | English |
| Summary: | In the present work, three main dissimilar materials were used in friction welding i.e. 6061 aluminum alloy joined to pure alumina, alumina-25 wt. % YSZ and alumina-50 wt. % YSZ. The ceramic systems were fabricated by slip casting and subsequently sintered at 1600 ºC, while the metal aluminum alloy was cut and polished. The diameter of both the ceramic and metal rods was 16 mm. The effects of friction welding process parameters (rotational speed, friction time, joint geometry and applied pressure) on the dissimilar material joints characteristics were evaluated. The thermal analysis of base materials plays an important role in the possibility of friction heat generation and increasing the friction temperature between two surfaces. The results in this study showed that pure alumina was able to be friction welded to 6061 aluminum alloy at rotational speeds between 1250 and 2500 rpm, while alumina-25, 50 wt. % YSZ were joined at lower rotational speeds (630 rpm to 900 rpm). It was also observed that joint between alumina – 25 wt % YSZ composite and 6061 aluminum alloy at lower rotational speed of 630 rpm produced the highest joint strength but lower microhardness with good microstructure as compared to the other ceramic components joint. On the other hand, the mechanical strength of friction-welded pure alumina / 6061 aluminum alloy components was affected by the rotational speed which increases in strength with increasing rotational speed. The effect of rotation speed, joint geometry, friction time, applied friction pressure and degree of deformation appears to be high on the 6061 aluminum alloy than on the ceramic part. The effect of increasing rotational speed over
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the friction-welding joint was that both the temperature gradient and the axial shortening increased as a result of more mass being transferred out of the welding interface. The results also indicated that the friction time and ceramic face geometries have a significant effect on the joint microstructure, microhardness and bending strength. The XRD data showed that changes in metal alloy crystallite size, density and lattice parameters occurred over the test distances at different rotational speeds. The grains were fine and dynamically recrystallized near the weld interface and elongated after different distances. The fracture surfaces were different with different parameters giving either ductile or brittle failure. |
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