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Go to Editorial ManagerBrazing is one of the best methods of graphite to graphite or to metals joining. But the major problem associating the graphite brazing is the poor wetting by the conventional molten fillers. For this reason, scientists have produced a special filler metal based on active elements which interacts with graphite to form carbides. Also, recently another technique to overcome the wetting problem was introduced by H. Ohmura and T. Yoshida. It included inserting an intermediate layer of pure iron foil inside the copper filler. In the present work, another filler combination of Cu/ steel/Cu foils is proposed as new filler technique for graphite brazing. It was found that, it produced a succeeded joint with a good properties consisted of a columnar phase which resulted from the partially dissolution of iron in molten copper. Additionally, the increasing of brazing time caused reducing the thickness of the steel central layer and increasing the thickness of the columnar phase layers. The x-ray diffraction test developed that, the joints contained two carbide types, iron and copper free elements.
This experimental research depicts the role of coating hot surfaces by graphite and graphene on the process of heat dissipation from these hot surfaces. Three aluminum specimens have been prepared for test, one of theme is coated by graphite, another one by graphene a while the third is left free of coating for comparison purpose. Each specimen is tested separately in a home-made wind tunnel. A plate electrical heater is adhered on the bottom of the specimen to simulate the generated energy by a heat sink. A heat sink composed of high thermal conductivity was applied between the heater plate and the base plate of heat sink to reduce the contact resistance to heat flow. The experiments are conducted with four turbulent Reynolds number. The results reveal that the sample coated by graphene exhibits the best thermal dissipation while the uncoated specimen shows the worst thermal performance.