ANALISIS SIFAT KOROSI HASIL COR TERHADAP TEMPERATUR PEMBUATAN PROPELLER PERAHU MENGGUNAKAN METODE SAND CASTING

The propeller is one of the engine components that plays an important role in the construction of water transportation (ships). The propeller has a very large function
because the speed of the ship is determined by the condition of the propeller. Propeller advantage is needed to minimize or reduce the occurrence of damage (broken). Making propellers by casting with aluminum scrap and using sand molds with pouring temperature variations of 400°C, 500°C and 550°C. The tests carried out were chemical composition tests (spectrometer), microstructural observations,
and corrosion tests (potentialodynamic polarization). The results of the chemical composition test (spectrometer) showed that the elements contained were Al-Si
alloy with a percentage of 92.92% Al, then 3.84% Si. The results of microstructural observations showed that the largest porosity was obtained at a temperature of
500°C with an average porosity value of 9.69 μm compared to a temperature of 550°C with the smallest porosity value obtained with an average of 7.17 μm the higher the pouring temperature, the higher the porosity value decreasing. Then it can be seen the results of the potentiodynamic corrosion test on 3.5 wt% NaCl media from the tested 450°C, 500°C, 550°C samples. The higher the pouring temperature, the greater the corrosion current (Icorr) and corrosion rate (Ecorr). If the lower the value of the corrosion rate, the corrosion resistance increases. So
that the smaller the shaft size, the corrosion resistance increases.

Keywords: Casting, Corrosion, Propeller, Microstructure, Spectrometer, Temperature.