Resources Recycling (자원리싸이클링)

The Korean Institute of Resources Recycling (한국자원리싸이클링학회)
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Ultrasonic Immersion-steam Cleaning and High Temperature Drying Process for Removing Cutting Oil on Titanium Turning Scraps

타이타늄 터닝 스크랩 내 절삭유 제거를 위한 초음파 침지-스팀 및 고온 건조 공정

  • Chae, Jikwang (Division of Advanced Materials Engineering, College of Engineering, Jeonbuk National University) ;
  • Yoo, Suhwan (Division of Advanced Materials Engineering, College of Engineering, Jeonbuk National University) ;
  • Oh, Jung-Min (Division of Advanced Materials Engineering, College of Engineering, Jeonbuk National University) ;
  • Lim, Jae-Won (Division of Advanced Materials Engineering, College of Engineering, Jeonbuk National University)
  • 채지광 (전북대학교 신소재공학부) ;
  • 유수환 (전북대학교 신소재공학부) ;
  • 오정민 (전북대학교 신소재공학부) ;
  • 임재원 (전북대학교 신소재공학부)
  • Received : 2020.11.23
  • Accepted : 2021.01.27
  • Published : 2021.02.28
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Abstract

The recycling of titanium turning scraps requires the removal of cutting oil and other contaminants remaining on the surface. In this study, an experiment was conducted in which titanium scraps were cleaned by a combination of ultrasonic immersion-steam cleaning and subsequent drying at high temperature. To determine the removal mechanism of cutting oil, the contact angle between titanium surface and cutting oil was measured. The result confirmed the optimum condition of the immersion solution of the titanium turning scraps. In the case of immersion cleaning of Na4P2O7 aqueous solution, the degree of carbon removed in the cutting oil was the highest at 50℃, and it was confirmed that the carbon content obtained from the combination of steam cleaning and ultrasonic immersion-steam cleaning was lower than that from steam cleaning after ultrasonic immersion. The oxidation and decomposition behaviors of cutting oil were investigated using Thermogravimetric analysis (TGA) and the result was applied in the high temperature drying process. From the results of the high temperature drying tests, it was concluded that 200℃ is the optimal drying temperature.

타이타늄 터닝 스크랩을 재활용하기 위해서는 표면에 남아있는 절삭유나 기타 오염물을 제거해야할 필요가 있다. 본 연구에서는 초음파 침지-스팀의 복합 세척 공정을 활용하여 타이타늄 스크랩을 세척하고, 건조 조건을 달리하여 절삭유를 제거하는 실험을 진행하였다. 또한 절삭유 제거 메커니즘 확인을 위한 접촉각 측정을 통해 타이타늄 터닝 스크랩의 침지 용액 최적 농도를 확인하였다. 피로인산나트륨 용액에 침지 세척 시 50℃에서 절삭유 내 탄소 제거율이 가장 높았으며, 스팀 세척-초음파 침지-스팀 세척 순으로 진행하는 것이 초음파 침지 후 스팀 세척을 실시하는 것보다 탄소 함량이 낮은 것을 확인했다. 타이타늄 스크랩의 TGA 분석을 통해 산화 및 절삭유의 분해 거동을 조사하고 고온 건조에 적용하였다. 건조 후 탄소와 산소 함량을 고려 시 200℃에서 2시간 건조를 하는 것이 최적의 조건임을 확인하였다.

Keywords

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