Fig.7. Polished Samples of Al MMC —S ns pe pas The two most suitable SiC reinforced Al MMC machined cylinders are to be chosen such that they have the minimum gap in between the joining surfaces. The faying surfaces are to be flattened by polishing them by sand papers starting from the coarsest anc ending with the finest grade. While they are polished the lubrication is done by using a mixture of kerosene anc paraffin in the ratio 1:1. The faying surfaces were soakec in acetone and dried by a hot blast of air. One of the cylinders (the bigger diameter cylinder in case the cylinders are of unequal diameters) has to be covered with cello tape and then the other cylinder (small diameter cylinder) has to be rotated on the surface of the cello tape. This is done to remove the glue from the cello to which the copper-silver power may Fig. 2. Programmable Electric Furnace (Jadavpur University) supply should be sufficient or the specimen might get oxidised. The specimen is then taken out of the furnace and cooled naturally in air for 10 minutes. Fig. 4: The fixtures for shear testing The bond centreline should be visible in between the two fixtures. This ensures that the force is exerted on the bond. The fixture along with the sample is then placed in the shear testing machine. Fig. 5: Shear Testing Machine (Jadavpur University) Fig. 7: Diamond cutter The sample is then polished in the variable speed grinder polisher with diamond paste and extender oil for lubrication to get mirror polish which is necessary for metallography. Fig.17.: Nariable speed grinder polisher (Jadavpur University) Fig. 9: The sample being cut near the circumference cut Fig.10. The sample being along the diameter Ultimate Tensile Stress = 48 MPa ‘/g. 14: Bond centreline at the central region for 9 hours holding time at 520°C at 5x magnification Fig. 78: Bond centreline at the central region for 9 hours holding time at 520°C at 20x magnification
