The role of nanocatalyst of pearl oyster shell in pack carburizing process on mechanical and physical properties of AISI 1020 steel

Mechanical Engineering Department, Faculty of Science and Technology, Sanata Dharma University, Paingan, Maguwoharjo, Depok, Sleman, Yogyakarta

^* Corresponding author: ketut@usd.ac.id

Abstract

The most commonly used metal material in the industry today is steel. Steel is classified based on its carbon content. There are high-carbon steel, medium-carbon steel, and low-carbon steel. The steel used in this research is low-carbon steel, namely AISI 1020 steel, with a carbon content of around 0.1% to 0.3%. With a low-carbon content, the hardness is also low. Pack carburizing is carried out to overcome this issue. The media used are coconut shell nanocarbon and pearl oyster shell nanocatalyst. Specimens were made with a mixture of nanocatalyst variations given around 0%, 10%, 20%, and 30% with the use of 900º C temperature with a holding time of 60 minutes. Preparation of nano-sized media using the High Energy Milling (HEM) process using a shaker mill machine. The treated specimens were then subjected to Vickers hardness testing with 5 kg and 200 gf loading, microstructure observation, and FTIR observation. The highest Vickers macro hardness test was obtained through the 20% nanocatalyst variation, resulting in a hardness value of 255 HV. The increase that occurred compared to without treatment increased by 91%. Then the micro Vickers hardness testing resulted in a value of 399 HV. The resulting microstructure is evenly distributed pearlite grains and gradations of ferrite grains. The carburizing depth is achieved optimally through a 20% variation of pearl clam shell nanocatalyst, with a depth of ± 0.19mm. Then FTIR observation also shows the presence of new groups of vinylidene-type alkene compounds. These compounds are flammable and volatile, so they can provide additional energy in the pack carburizing process.