SURFACE CHEMICAL PROPERTIES MODIFICATION OF LOW CARBON STEEL ST-37 WITH FLY ASH BASED GEOPOLYMER WITH ADDITION OF NANOCELLULOSE FROM RICE HUSK

• Main Author: Azarya, Yosia
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/41799
• Institution: Institut Teknologi Bandung

Corrosion is the most common problem in the use of low carbon steel in the industry. The wide field of use, good mechanical properties, and low prices are the reasons for continuing to use low carbon steel compared to stainless steel. One way to prevent corrosion is to use a coating derived from inorganic material. Fly ash-based geopolymer has the potential to be used as a coating on low carbon steel, especially the abundant availability of fly ash in Indonesia. In addition, nanocellulose and chitosan as a coupling agent can be used as geopolymer alloys to improve the performance of the resulting geopolymer coating. This study aims to determine the corrosion resistance of geopolymers as low carbon steel coatings and the effect of alloys on corrosion resistance. From the results of X-Ray Fluorescence characterization, it can be concluded that the fly ash used for geopolymer precursors is class F fly ash. Fly ash is activated by an alkaline activator solution to produce geopolymers, shown by the material undergoing setting and X-Ray Diffraction test that shows geopolymer characteristic compounds, namely Quartz and Mullite. Nanocellulose is synthesized from rice husks by acid hydrolysis method. The corrosion resistance of ST-37 coated with geopolymer and its alloys was tested by using Meteor Immersion and Electrochemical Impedance Spectroscopy (EIS). Immersion test results show that low carbon steel specimens coated with geopolymer coatings and alloys do not undergo corrosion but there is a phenomenon of leaching residual activator solution that does not react so that the corrosion rate values obtained are poor because the corrosion rate is based on calculating the weight loss. Geopolymer coating which uses chitosan as a coupling agent (G-K) shows the highest impedance value and has the best substrate-interface interface with minimal voids and good bonding due to interlocking between the Abstract Corrosion is the most common problem in the use of low carbon steel in the industry. The wide field of use, good mechanical properties, and low prices are the reasons for continuing to use low carbon steel compared to stainless steel. One way to prevent corrosion is to use a coating derived from inorganic material. Fly ash-based geopolymer has the potential to be used as a coating on low carbon steel, especially the abundant availability of fly ash in Indonesia. In addition, nanocellulose and chitosan as a coupling agent can be used as geopolymer alloys to improve the performance of the resulting geopolymer coating. This study aims to determine the corrosion resistance of geopolymers as low carbon steel coatings and the effect of alloys on corrosion resistance. From the results of X-Ray Fluorescence characterization, it can be concluded that the fly ash used for geopolymer precursors is class F fly ash. Fly ash is activated by an alkaline activator solution to produce geopolymers, shown by the material undergoing setting and X-Ray Diffraction test that shows geopolymer characteristic compounds, namely Quartz and Mullite. Nanocellulose is synthesized from rice husks by acid hydrolysis method. The corrosion resistance of ST-37 coated with geopolymer and its alloys was tested by using Meteor Immersion and Electrochemical Impedance Spectroscopy (EIS). Immersion test results show that low carbon steel specimens coated with geopolymer coatings and alloys do not undergo corrosion but there is a phenomenon of leaching residual activator solution that does not react so that the corrosion rate values obtained are poor because the corrosion rate is based on calculating the weight loss. Geopolymer coating which uses chitosan as a coupling agent (G-K) shows the highest impedance value and has the best substrate-interface interface with minimal voids and good bonding due to interlocking between the substrate and coating. Low carbon steel coated with geopolymer coating has an impedance above 10,000 ? at a frequency of 0.1 Hz. The use of nanocellulose in geopolymer coatings reduces the amount of porosity seen in SEM results. Based on corrosion testing on artificial brine solutions, it can be concluded that the use of chitosan on geopolymer coatings has the best results in increasing corrosion resistance of low carbon steel ST-37.