EFFECT OF ZIRCONIUM ADDITION ON THE CYCLIC OXIDATION RESISTANCE OF FE-14NI-9AL-7,5CR ALLOY AT TEMPERATURE OF 800, 900, AND 1000°C

• Main Author: Mufid Baihaqi, Ariza
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/47253
• Institution: Institut Teknologi Bandung

To meet the increasing need for electrical energy throughout the world, power plants that are capable of efficiently producing more electricity are needed. The efficiency of a power plant that uses a gas turbine depends on the operating temperature of the gas turbine. Efficiency of the gas turbine is increasing in line with increased operating temperature. Therefore, a gas turbine component with a material that can be used at high temperatures is needed. The Fe-14Ni-9Al-7,5Cr alloy is a material candidate for such need. One of the criteria used to determine the use of materials at high temperatures is oxidation resistance. Gas turbine operating conditions that are not fully stable cause the need for cyclic oxidation resistance. One way to increase cyclic oxidation resistance is to add zirconium (Zr) to the alloy. In this study Fe-14Ni-9Al-7,5Cr alloys added with Zr were made. The alloy was tested by cyclic oxidation to determine the effect of zirconium on the cyclic oxidation resistance and formed oxide layer. A series of experiments have been carried out to determine the effect of zirconium addition on the cyclic oxidation resistance of Fe-14Ni-9Al-7,5Cr alloys. Alloys of Fe-14Ni-9Al-7,5Cr with 0,1%, 0,5%, and 1,0% by weight addition of Zr were made. The cyclic oxidation test was carried out using muffle furnaces at atmospheric pressure and temperatures of 800, 900, and 1000°C for 50 cycles. Each oxidation cycle consists of 1 hour heating and 15 minutes cooling. Samples were weighed before being tested and after each cooling cycle. The relative oxide thickness is obtained by calculating the ratio of weight change and initial surface area of the sample. From the test the value of the relative oxide thickness against the test cycle is obtained. The cyclic oxidation rate was approached with the COSP model. The samples that were tested were characterized by XRD and SEM. Increasing the zirconium concentration or test temperature increases the thickness of the oxide formed. The oxides formed are mainly in the form of Al2O3 and ZrO2. The oxide layer quickly forms during initial cyclic oxidation. After that, the rate of oxide formation decreases until the thickness of the oxide tends to be constant. At temperatures of 1000°C the alloy Fe-14Ni-9Al-7,5Cr with 0,5%Zr has the best cyclic oxidation resistance with ???????? = 0,840931 mg2/cm4/hour and ????0 =1,522695×10-13 cm2/mg.