• Tribology and Lubricants
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• 제24권4호
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• pp.186-189
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• 2008

The flow induced vibration in the nuclear fuel assembly causes the fretting wear between the fuel cladding tubes and the supporting grids. The reduction in tube thickness due to the fretting wear could be related to the serious damage on nuclear fuel assembly. In this paper, the effect of the water flow on fretting wear of nuclear fuel cladding tube against supporting grid was investigated through the fretting wear tester with water spout equipment. The test results were compared with the data conducted in the stationary water. At stationary water environment the wear debris was trapped between fretting surfaces, and then the fretting wear occurred by three-body abrasion. However, in the case of water flow, the two-body abrasive wear was the dominant wear mechanism, because the wear debris was easily removed by water flow.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.263-268
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• 2000

The fretting damage of the contact between Zircaloy-4 and Inconel 600 have Investigated. A fretting wear tester was designed to be suitable for this fretting test. In this study, the number of cycles, slip amplitude and normal load were selected as main factors of fretting wear. As the result of this research the wear volume increased with the increase of loads, slip amplitudes and the number of cycles and was more affected by slip amplitudes rather than by load. According to SEM, stick, partial slip, gross slip were observed on the surface of both specimens and wavy worn surfaces as the typical fretting damage were also Investigated due to accumulation of plastic flow.

• Tribology and Lubricants
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• 제14권4호
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• pp.88-94
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• 1998

The fretting wear characteristics of Zircaloy-4 tube in light water were investigated experimentally. A fretting wear tester was designed to be suitable for this fretting test. This study was focused on the effects due to the combination of normal load, slip amplitude and number of cycles as the main factors of fretting. The results of this study showed that the wear volume increased abruptly at slip amplitude above 100 ${\mu}{\textrm}{m}$, which is defined as critical slip amplitude of Zircaloy-4 tube in light water, and that under 160 ${\mu}{\textrm}{m}$ the wear volume decreased as load increased at the same slip amplitude.

• Tribology and Lubricants
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• 제15권1호
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• pp.83-89
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• 1999

The fretting wear behaviour of Zircaloy-4 tube used as the fuel rod cladding in PWR nuclear power plants has been investigated at the different test environment, in light water and in air as a function of slip amplitude, normal load, test duration and frequency. Zircaloy-4 tubes were used for both of oscillating and stationary specimens. A fretting wear tester was designed to be suitable for this fretting test. The wear volume and specific wear rate of Zircaloy-4 tube in water was greater than those in air under various slip amplitude. Delaminates and surface cracks were observed at low slip amplitude and high load of fretting test in water, but the traces of adhesion and plowing were observed at and above 200 Um. The water accelerates the wear of Zircaloy-4 tube at lower slip amplitude in fretting.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.71-77
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• 1999

The fretting wear characteristics of STS304 steel in seawater were investigated experimentally. A fretting wear tester was designed to be suitable for this fretting test. This study was focused on the effects due to the combination of normal load, slip amplitude and number of cycles and corrosive environment as the main factors of fretting. The results of this study showed that the wear volume increased abruptly at slip amplitude between 70${\mu}{\textrm}{m}$~ 100${\mu}{\textrm}{m}$ by fracture of oxide layers but above that slip amplitude the wear volume increased steadily.

• KSTLE International Journal
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• 제10권1_2호
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• pp.33-36
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• 2009

The nuclear steam generator is composed of a bundle of tubes. The length of these tubes is very long, but their diameter is small. Fluid exists inside of the steam generator and its flow causes vibration, therefore these tubes are supported by anti-vibration bars. The wear damage due to the vibration is known as fretting wear, which should be minimized to ensure the safety of the plants. Research needs to be done about decreasing the amount of fretting wear. Hard coatings have proven to be very effective in reducing the amount of wear. The commercial coatings of TiN and CrN have excellent wear resistance and are used to protect the Inconel tube from fretting wear. The tube-on-flat type tester was used for conducting the fretting wear tests. It was found that the wear amounts of the coated tubes decreased depending on the coating thickness. CrN was found to be very effective in reducing the wear, while the wear amounts were dependent on the coating thickness in the case of TiN and a thick coating of TiN was very effective on wear resistance.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제27회 춘계학술대회
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• pp.55-63
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• 1998

The fretting wear characteristics of Zircaloy-4 tube in light water were investigated experimentally. A fretting wear tester was designed to be suitable for this fretting test. This study was focused on the effects due to the combination of normal load, slip amplitude and number of cycles as the main factors of fretting. The results of this study showed that the wear volume increased abruptly at slip amplitude above 100$\mu$m, which is defined as critical slip amplitude of Zircaloy-4 tube in light water, and that under 160$\mu$m the wear volume decreased as load increased at the same slip amplitude.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.111-116
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• 2004

Li-complex and urea type greases (each 10 species) which were furnished by Chang-Am LS, analyzed anti-wear performance into fretting wear tester & four-bail wear tester. from the results of fretting wear test, the wear volume of Li-complex greases are $4.6\~8.9mg\;and\;8.3\~14.4mg$ with the test of urea greases. The anti-wear performance for 4-ball wear test of greases produced results around 0.5mm at the value of WSD. The grease life performance were evaluated by SKF-ROF Grease Tester and wheel bearing life tester. From the results of SKF-ROF tester, the life performance evaluated by whole working time produced results $50\~300hr$ with the Li-complex greases and 100-1000hr with the urea greases. That is to say, in spite of severe condition at the higher of $10^{\circ}C$ reaction temp, the life performance with Urea type greases are much superior to Li-complex type greases. Prior to wheel bearing life tester, the grease selected performance evaluation(=anti-wear test) are tested by wheel bearing tester. In this results, we can confirm results those are similar with SKF-ROF tester. In this study, we can draw two major conclusions, one is that Li-complex greases are superior to urea greases with anti-wear properties and the other is that urea greases are much superior to Li-complex greases with life performance.

• Tribology and Lubricants
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• 제24권5호
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• pp.250-254
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• 2008

The steam generator of nuclear power plant is composed with the bundles of long tubes. It is exposed fluid flow and weak in the vibration. The tubes are supported by anti-vibration bars. Due to vibration the wear damage is called as the fretting wear. It should be minimized for the safety of the plants. The hard coatings are very effective to reduce the amount of wear. The coatings of TiN and CrN are introduced in this study to protect the fretting surfaces. The tube-on-flat type tester was used for fretting wear tests. The results show that the wear amounts of the coated tubes were decreased depending on coating thickness. CrN was very effective to reduce the wear. In case of TiN the wear amounts were dependent on the coating thickness. Thick coating of TiN was very effective for wear resistance.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.73-79
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• 2002

상온 공기분위기에서 두 가지 형태의 스프링에 대한 연료봉 피복관의 마멸실험을 수행하였으며 다음과 같은 결론을 얻었다. (1) 가장 큰 마멸부피는 스프링 형상이 오목할 경우 틈이 존재할 때 발생하였으며, 형상이 볼록한 경우에는 접촉하중이 존재할 때 마멸부피가 크게 나타났다. (2) 접촉형상이 오목한 형태로 연료봉을 감싸고 있는 경우, 마멸입자의 방출은 다소 어렵게 되며 이에 따라 마열거동은 표면에서 생성되는 마멸입자가 외부로 방출되는 용이성에 따라 최종적으로 마멸부피는 결정된다. (3) 볼록한 형상의 스프링의 경우, 충격마모에 대하여 저항성을 보였으나, 접촉하중이 존재할 경우 높은 마멸량을 보이고 있다. (4) 오목한 형태의 스프링 조건에서 축 방향의 마멸보다는 횡 방향의 마멸량이 더 낮게 나타났다. 이것의 주된 원인은 오목한 형태의 스프링이 충격하중에 있어 가이드역할을 할 가능성이 있는 것으로 나타났다. 또한, 양 방향 모두 마멸입자의 고착 흔적이 나타났으나 횡 방향의 경우 연삭에 의한 경향이 보다 뚜렷이 나타났다.