• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.167-168
• /
• 2002

In this study, the effects of oxide layer formed on the wear tracks of TiN coated silicon wafer on friction characteristics were investigated. Silicon wafer was used for the substrate of coated disk specimens, which were prepared by depositing TiN coating with $1\;{\mu}m$ in coating thickness. AISI 52100 steel balls were used for the counterpart. The tests were performed both in air for forming oxide layer on the wear track and in nitrogen to avoid oxidation. This paper reports characterization of the oxide layer effects on friction characteristics using X-ray diffraction (XRD). scanning electron microscopy (SEM) and friction force microscope (FFM).

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.1
• /
• pp.240-247
• /
• 2003

The tribological characteristics of FDTS (1H, 1H, 2H, 2H-Perflurodecyltrichlorosilane) SAM (self-assembled monolayer) and OTS (octadecyltrichlorosilane) SAM treated by high temperature annealing have been investigated from the viewpoint of stiction, adhesion and friction in micro/nano scale. From the experimental results, it was found that OTS SAM gets destroyed at 20$0^{\circ}C$ and stiction, adhesion and friction coefficient increased, but FDTS SAM was stable up to 40$0^{\circ}C$. Also, it was found that the friction coefficient of normal OTS SAM below 20$0^{\circ}C$ is lower than that of FDTS SAM in micro/nano scale, but stiction and adhesion is vice versa. This work shows the importance of surface group of self-assembled monolayer in dictating the tribological characteristics and thermal stability.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.5
• /
• pp.171-179
• /
• 2003

An Amplitude Proportional Friction Damper (APFD) is considered in order to improve the characteristics of Coulomb friction damper. The frictional force is proportional to the amplitude in APFD system and the system is non-linear as is Coulomb damper system. A free vibration analysis on the 1-DOF system has made to demonstrate the characteristics of the APFD system. The results show that APFD system has similar damping characteristics to the viscous damper. Also, the solution for the response of a base-excited system with APFD is developed through the application of a Fourier series to represent the frictional force of APFD. It is assumed that no stick-slips occur during any portion of the steady-state oscillation.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.48 no.3
• /
• pp.277-283
• /
• 2012

The characteristics of abrasive wear on sliding speed of glass fiber reinforcement (GF/PUR) composites were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and surface roughness of these materials on sliding speed were determined experimentally. The major failure mechanisms were lapping layers, deformation of resin, ploughing, delamination, and cracking by scanning electric microscopy (SEM) photograph of the tested surface. As increasing the sliding speed the GF/PUR composites indicated higher friction coefficient. The surface roughness of the GF/PUR composites was increased as the sliding speed was higher in wear test.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.49 no.4
• /
• pp.492-499
• /
• 2013

The characteristics of abrasive wear of the rubber matrix composites filled with nano sized silica particles were investigated at ambient temperature by pin-on-disc friction test. The range of volume fraction of silica particles tested are between 11% to 25%. The cumulative wear volume and friction coefficient of these materials on particle volume fraction were determined experimentally. The major failure mechanisms were lapping layers, deformation of matrix, ploughing, deboding of particles and microcracking by scanning electric microscopy photograph of the tested surface. The cumulative wear volume showed a tendency to increase nonlinear with increase of sliding distance. As increasing the silica particles of these composites indicated higher friction coefficient.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1998.04a
• /
• pp.307-313
• /
• 1998

This paper presents the experimental results of the friction characteristics of double lip-type oil seals which show an improvement in sealing performance over single lip-type oil seals. The major differences between two oil seals are the number of contact lip and seal materials; Nitrile Butadine Rubber(NBR) and urethane rubber. The measured results show that the friction torque of double lip seals shows 12-17% increases compared with those of single lip-type seals. But the sealing performance and service life of double tip oil seals have been increased and stabilized due to an optimized design of the seal lip and material properties.

• Journal of Mechanical Science and Technology
• /
• v.16 no.4
• /
• pp.468-475
• /
• 2002

This paper reports on the friction characteristics of a piston ring pack with consideration of mixed lubrication. The analytical model is presented by using the average flow antral asperity contact model. The effect of operating condition, and design parameters on the MOFT, maximum friction force, and mean frictional power loss are investigated. Piston ring prick shows mixed and hydrodynamic lubrication characteristics. From the predicted results, it was fand that the ring tension and height of surface roughness have great influence on the frictional power losses in a ring pack. Especially, ring tension is a dominant factor for the reduction of friction loss and maintenance of oil film thickness.

• KSTLE International Journal
• /
• v.9 no.1_2
• /
• pp.31-35
• /
• 2008

DLC (Diamond Like Carbon) films have predominant tribological properties like a high hardness, low friction and high chemical resistance; therefore, DLC films are applied in a wide range of industrial fields. This paper evaluated the characteristics of DLC films deposited on bearing steel with different hardness by RF-PECVD (Radio Frequency - Plasma Enhanced Chemical Vapor Deposition) method. Si-interlayer was deposited on bearing steel to improve adhesion strength by RF-Sputtering method. The DLC film structures were analyzed with Raman spectra and Gaussian function. Adhesion strength of DLC films was measured with a scratch tester. Friction and wear test were carried out with a ball-on -disc type to investigate the tribological characteristics. Experimental results showed that DLC films deposited on bearing steel under same deposition condition have typical structure DLC films regardless of hardness of bearing steel. Adhesion strength of DLC film is increased with a hardness of bearing steel. Friction coefficient of DLC film showed lower at the high hardness of bearing steel.

• Journal of Drive and Control
• /
• v.9 no.4
• /
• pp.26-31
• /
• 2012

Friction reduction between sliding hydraulic machine components is required to improve efficiency and reliability of hydraulic machineries. It is recently reported that surface texturing on sliding bearing surfaces can reduce the friction force highly. In this paper, numerical analysis is carried out to investigate the effect of dimple numbers and inlet boundary pressures on the lubrication characteristics of a parallel sliding bearing using a commercial computational fluid dynamics (CFD) code, FLUENT. The results show that the pressure distribution, load capacity, dimensionless friction force and leakage with dimple number and their locations, and inlet pressures. The overall lubrication characteristics are highly affected by dimple numbers and boundary pressure. The numerical method adopted and results can be used in design of efficient hydraulic machine components.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.06a
• /
• pp.96-99
• /
• 2001

The fatigue life of support bearings is one of the most critical factors for the performance of a control rod driving mechanism. They are operated at high temperature and high pressure and especially lubricated with dramatically low viscosity water. The support bearing is made of standardized 440C stainless steel, and it supports thrust load including the weight of the driving system and external force. Friction and wear characteristics of this material operating under severe lubrication condition is not well known yet, although it is expected to be changed with respect to temperature and boundary pressure. So the friction characteristics are investigated in sliding conditions using the reciprocating tribometer which can simulate the operating conditions. Highly purified water is used as lubricant, and the water is heated up and pressurized. Friction farce on the reciprocating specimens is monitored by the load cells. The results of the experiments are presented in this paper.