Investıgatıon of productıon parameters of porous copper surfaces used on heat exchangers

In this study, it has been investigated that the effects of production parameters on the porosity of surfaces have been produced from copper powders used on heat exchangers.In this context, with several experiments done, it has been achieved that -140/+105, -105/+75, -75/+53 and -53/+44 µm dendritic copper powders respectively bonded to a 0,1 mm copper substrate by hot compaction under 250 and 550 oC temperature and 5, 15, 50 MPa compaction pressures. Total amount of 47 test specimens have been obtained, however it has been observed that some of them did not bond to the substrate and their green density could not reach to a reasonable value. Two types of punches have been used, one of them with a flat surface and, the other one with a profile surface.Test specimens of 55 mm diameter, obtained from hot compaction tests, have been exposed to sintering process at 860 oC for 30 minutes. They have been mounted after being cut into 10x20 mm sections, then they have been observed on the surface by optical microscope to measure the porosity by using the image processing software called Image-J. After then, surface morphology of the specimens have been analyzed by scanning electron microscope. As the result of the observations, the production parameters have been compared considering the porosity levels of the test specimens, and optimum requirements of manufacturing parameters are listed for the usage in heat exchangers. Consequently, % 34 porosity for the flat surface by -140/+105 µm powder size, 350 oC ve 5 MPa whereas % 29 for the profile surface by -105/+75 µm powder size 350 oC and 15 MPa have been achieved.