Journal of the Korea Academia-Industrial cooperation Society (한국산학기술학회논문지)

The Korea Academia-Industrial cooperation Society (한국산학기술학회)
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Studies on the synthesis and characteristics of calcium sulfonate complex grease

칼슘 술폰산염 컴플렉스 그리스 합성과 특성 연구

  • Received : 2019.04.10
  • Accepted : 2019.07.05
  • Published : 2019.07.31
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Abstract

In this study, we synthesized a calcium sulfonate complex grease and a lithium complex grease to investigate their physical, rheological and tribological properties. The thermal stability of the calcium sulfonate was higher than $300^{\circ}C$ and the lithium complex grease was $245^{\circ}C$ in the dropping point test. In the grease viscosity measurement, the calcium sulfonate complex grease was measured as $7.0Pa{\cdot}s$ and the lithium complex grease was as $4.5Pa{\cdot}s$. Therefore, it was confirmed that the calcium sulfonate complex grease is superior to the lithium complex grease in terms of thermal stability and cohesiveness. In the 4-ball wear test, the calcium sulfonate complex grease was measured to be 0.43 mm and the lithium complex grease to 0.85 mm. In the 4-ball extreme pressure test, calcium sulfonate complex grease was measured as 620 kgf and the lithium complex grease was as 125 kgf. Therefore, it was confirmed that the calcium sulfonate complex grease is superior to the lithium complex grease in abrasion resistance and load-bearing property. It was found that the calcium sulfonate complex grease is more effective than the lithium complex grease in the lubrication at high temperature and high load.

본 연구에서는 칼슘 술폰산염 컴플렉스 그리스와 리튬 컴플렉스 그리스를 합성하고, 그리스의 일반 물성, 유변학적 특성 및 윤활성능을 비교하였다. 내열성 시험인 적점 시험에서 칼슘 술폰산염 컴플렉스 그리스의 열 안정성은 섭씨 300도 이상, 리튬 컴플렉스 그리스는 섭씨 245도로 측정되었다. 점도시험에서 칼슘 술폰산염 컴플렉스 그리스는 7.0 파스칼 초, 리튬 컴플렉스 그리스는 4.5 파스칼 초로 측정되었다. 따라서 칼슘 술폰산염 컴플렉스 그리스가 리튬 컴플렉스 그리스보다 내열성 및 점착성면에서 우수함을 확인하였다. 4-ball 내마모시험에서 칼슘 술폰산염 컴플럭스 그리스는 0.43 밀리미터, 리튬 컴플럭스 그리스는 0.85 밀리미터로 측정되었고, 4-ball 내하중성 시험에서 칼슘 술폰산염 컴플렉스 그리스는 620 킬로그램중, 리튬 컴플렉스 그리스는 125 킬로그램중 으로 측정되었다. 따라서, 칼슘 술폰산염 컴플렉스 그리스가 리튬 컴플렉스 그리스보다 내마모성 및 내하중성에서 우수하였다. 위 시험결과로 고온 및 고하중의 윤활에서는 칼슘 술폰산염 컴플렉스 그리스가 리튬 컴플렉스 그리스보다 더 효과적인 것을 알 수 있었다.

Keywords

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Fig. 1. Manufacturing process of calcium sulfonate complex grease.

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Fig. 2. Chemical structure of calcium sulfonate complex grease.

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Fig. 3. Manufacturing process of lithium complex grease.

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Fig. 4. Chemical structure of lithium complex grease.

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Fig. 5. FTIR-ATR spectrum of overbased calcium sulfonate before conversion.

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Fig. 6. FTIR-ATR spectrum of overbased calcium sulfonate after conversion.

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Fig. 7. Results of 4-ball wear test.

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Fig. 8. Results of 4-ball extreme pressure test.

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Fig. 9. Evaluation of rheology at sheer rate of 300 s-1; (a) calcium sulfonate complex grease and (b) lithium complex grease.

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Fig. 10. Stress sweep curves of greases; (a) G' of calcium sulfonate complex grease, (b) G'' of calcium sulfonate complex grease, (c) G' of lithium complex grease, and (d) G'' of lithium complex grease.

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Fig. 11. Stress sweep curves of greases; (a) calcium sulfonate complex grease and (b) lithium complex grease.

Table 1. Properties of base oil

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Table 2. Properties of overbased calcium sulfonate

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Table 3. Test items for grease

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Table 4. Test values of greases

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