2023, Vol.33, No.6

Journal of the Korean Crystal Growth and Crystal Technology 2023 KCI Impact Factor : 0.19

pISSN : 1225-1429 / eISSN : 2234-5078
https://journal.kci.go.kr/jkcgct

Cobalt sulfide nanocomposites were synthesized through a simple hydrothermal method as anode materials forsodium ion batteries (SIBs). In this work, a cobalt sulfide nanoparticle (CoS-NF) and a cobalt sulfide nanocompositeintegrated with reduced graphene oxide (CoS@G-NC) were fabricated for electrochemical energy storage performance ofbattery. The as-prepared CoS@G-NC electrode exhibited reversible and stable cycle performance (62 % after 30 cycles atcurrent density of 200 mA g-1). The improved electrochemical property was attributed to the small grain growth and uniformdistribution of cobalt sulfide during synthesis, which maximized the diffusion pathway for sodium ions and effectivelysuppressed the delamination and volume expansion of cobalt sulfide during the conversion reaction. The results providepromising anode materials for next-generation SIBs.

Raw mix burnability is an especially crucial factor in cement manufacturing technology, and it depends on the physical, chemical and mineralogical properties of each raw material. In this article, we compared the difference of burnability between the domestic and Japanese fly ash as cement raw materials by using Lafarge and Polysius evaluation method. Regardless of the type or amount of fly ash used, it was found to be more combustible when using fly ash. In both case, burnability improves as the amount of fly ash increases, especially the improvement in bunarbility is remarkable up to 3%. In conclusion, as the amount of fly ash increases within the range allowed by cement quality, burnability of raw materials improves, and thus the fuel cost required for the firing of clinker can also be expected to be reduced.

This paper describes the finite element analysis and die design change of cold heading punching process toincrease the cold forging tool life and reduce the tool wear and stress concentration. Through this study, the optimizationof punch tool design has been studied by an analysis of tool stress and wear distribution to improve the tool life. Plasticdeformation analysis was carried out in order to understand the cold heading process between tool and workpiece stressdistribution. Cold heading punch die design was set up to each process with different four types analysis progressing, thecold heading punch dies shapes with combination of point angle and punch edge corner radius shapes of cold forging dies,punch die material properties and frictional coefficient. The design parameters of point angle and corner radius of punchdie geometry, die material properties and frictional coefficient were selected to apply optimization with the DoE (design ofexperiment) and Taguchi method. DoE and Taguchi method was performed to optimize the cold heading punch die designparameters optimization for bolt head cold forging process, it was possible to expect an reduce the cold heading punch diewear to the 37 % compared with current using cold heading punch in the shop floor.