The investigation of weldability of al matrix-Al2O3 reinforced composite materials with solid state bonding methods

SUMMARY Master Thesis THE INVESTIGATION OF WELDABILITY OF AL MATRIX - AL2O3 REINFORCED COMPOSITE MATERIALS WITH SOLID STATE BONDING METHODS SONER BUYTOZ Fırat University Graduate School of Natural and Applied Sciences Department of Metallurgy Education 1999, Page: Diffusion welding is a solid state bonding method in which the matched surfaces of two similar or dissimilar materials are held at a temperature below the melting points of the materials, under a bonding pressure far below the yielding stresses of the materials for a time enough to form a metallurgical bond without effecting the properties of the materials. This method is suitable especially for the materials such as ceramics, composites and exotic materials, which can not be bonded with conventional fusion welding methods. Composites are not so much suitable to join with fusion welding because of reinforcements in their structures. Diffusion bonding seems the most convenient method to join these materials since it is performed in solid state.VI In this study an aluminum matrix AI2O.1 reinforced composite (Al/AbO.i/lOp) was bonded with diffusion welding. The composite was produced using fheological casting method. The reinforcement is AI2O.1 particles with a size of average 60 u.m. After casting it was seen that the particles were distributed homogeneously in the matrix. In the study, the specimens were prepared in the dimensions of 10x10x10 mm from the bars casted. The surfaces of the specimens were polished with 1200 mesh emery paper and diamond paste. The surface roughness were measured with Sunsurf Mitutoyo Profilometer as 0,05 u.m and 0,19 (.im for diamond paste and emery paper respectively. The polished surfaces were cleaned with ethanol and then matched using a mechanical device to apply the bonding pressure. The experiments were conducted in a tube furnace prepared by us, under an argon protective atmosphere. The bonding pressures, bonding times and surface roughness were chosen as 1 and 2 MPa, 1.5 hours and 0.05 u.m and 0.19 |.im respectively. The experiments were performed in two different temperatures as 550 °C and 600 °C. The interfaces of the joints were examined with optical microscope, SEM and EDS. As a result, the best joint was optianed in the specimen with a surface roughness of 0.05 |.im bonded at 2 MPa, 600 °C and in 90 minutes. In the firstchapter of this study the subject is introduced. In the second chapter information about the diffusion bonding, mechanisms and parameters are given comprehensively. In the third chapter, composite materials and their joining methods are dealt with. In the fourth chapter experimental studies, in the fifth chapter the results of the experiments are given. In the sixth and final chapter, the results were concluded and recommendations are given. Key Words: Diffusion Bonding, Diffusion Welding, Solid State Bonding, Al Composite.