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Stainless steel is an alloy steel with corrosion (rust) resistance properties. However, the good corrosion and wear resistance properties of stainless steel also require continuous improvement in its performance and service life, especially in highly aggressive environments. One approach to changing the material structure is by using a mixture based on natural carbon, such as robusta coffee grounds. Robusta coffee grounds will be converted into carbon using a pyrolysis process at a temperature of 1000°C with a holding time of 1 hour. This carbon will be used as a coating material on 316L stainless steel with a variety of pack carburizing and quenching processes and temperatures with a holding time of 1 hour, then it will undergo a testing process that includes: thermal conductivity testing, and corrosion rate testing. In the quenching process, the thermal conductivity value of 900°C has a thermal conductivity value of 20.556 W/m°C, 800°C has a thermal conductivity value of 19.669 W/m°C and a temperature of 700°C with a thermal conductivity value of 18.930 W/m°C. while in the pack carburizing process, the temperature of 900°C has a thermal conductivity value of 20.101 W/m°C, and 800° has a thermal conductivity value of 19.54684 W/m°C, while at 700°C the thermal conductivity value is 18.916 W/m°C. At the raw corrosion rate has a corrosion rate value of 7.614 mm/year, in the quenching process of 700°C has a corrosion rate of 12.781 mm/year, while the temperature of 900°C with a corrosion rate value of 18.401 mm/year, and in the pack carburizing process of 700°C has a corrosion rate value of 9.699 mm/year temperature 900°C with a corrosion rate value of 13.234 mm/year. The better process in thermal conductivity is quenching, because it has a faster time but has a high conductivity value, while for the best corrosion rate is the pack carburizing process because it has a smaller corrosion rate value compared to the quenching process

His study aims to investigate the effect of temperature variation in pack carburizing and quenching processes on the microstructure and surface hardness of Stainless Steel 316L. The pack carburizing process was conducted using activated carbon derived from robusta coffee grounds at temperatures of 700°C, 800°C, and 900°C with a holding time of 60 minutes. Subsequently, a quenching process was carried out using oil mixed with activated carbon to lock the diffused carbon. The material was tested for mass change, microstructure (via SEM), and surface hardness (using the Vickers method). The results show that increasing temperature significantly affects carbon diffusion and hardness improvement. The highest hardness value was obtained from the quenching process at 900°C with 330 HV, while pack carburizing at the same temperature resulted in 292 HV. The microstructure revealed more dominant Martensitic formation in the quenching process. Therefore, heat treatment with rapid cooling proves to be more effective in enhancing hardness and modifying the microstructure of Stainless Steel 316L.    

Along with the times, the availability of fossil energy is decreasing, especially natural gas and coal, before using fossil energy, humans have used biomass as an energy source. Indonesia has many plantation commodities, one of which is coffee which is the fourth largest coffee producer in the world. Coffee grounds are the main waste produced by coffee shops and are usually only thrown away. The main ingredients in this study were arabica coffee grounds and robusta. By using robusta composition 60% arabica 40%, robusta 50% arabica 50% robusta 40% arabica 60%. In addition, briquettes are tested for hardness by making points on the surface of the briquettes using a durometer shore A tool of 30 points, then a calorimeter bomb test is carried out to obtain the calorific value content. The result obtained from the highest hardness value is briquettes with a robusta mixture of 50% arabica 50% with a value of 23.7 HA, while the highest calorific value is found in a robusta mixture of 60% arabica 40% with a value of 4526.85 cal / gram.

Coffee grounds are waste produced from making coffee drinks, most of which are produced by coffee shops and usually this waste is just thrown away. Careless disposal of coffee grounds waste will certainly cause environmental damage, therefore one of the uses of coffee grounds waste in this research is as briquettes. The main ingredients used are robusta and arabica coffee grounds with mixed variations using the composition of 60% robusta, 40% arabica, 50% robusta 50% arabica and 40% arabica 60% robusta. The theoretical heating value calculation method is carried out through the results of heating water using a variety of briquettes, while the actual heating value is obtained from the results of the bomb calorimeter test. From the calculation and testing results, it was found that the theoretical heating value was identical to the test results, where the highest heating value was obtained in briquettes of the 40% Arabica 60% Robusta variation, amounting to 4919.835 cal/g for theoretical calculations and 4526.85 cal/g for bomb calorimeter test results. The theoretical calculation error rate for each comparative variation is 13.07% for the 60% Arabica 40% Robusta variation, 7.97% for the 50% Arabica 50% Robusta variation, and 8.68% for the 60% Arabica 40% Robusta variation