• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1436-1440
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• 1996

The wear mechanism of material is an important mechanic property to select a material's life and a optimum work condition. Although there are many researches about a wear mechanism of material, the pin-on-disc type tribotester is widely known to us. It is difficult to add a variable and heavy load in the existing pin-on-disc type tribotester to estimate this wear mechanism. And due to a rotation of a disc, it is impossible to add a constant force. But we can solve this problem by using a hydraulic servo system. Therefore, in order to investigate a wear mechanism of materials, it is necessary to design a hydraulic pin-on-disc type tribotester and construct a controller against a variable disturbance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.285-291
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• 1998

A hydraulic pin-on-disk type tribotester was developed and it's performance was investigated experimentally. The estimate of the performance was accomplished by comparing those of the pneumatic and the dead-weight loading method. The reliability to the performance was conformed. By hydraulic loading method more accra'ate friction coefficient could be got.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.170.1-170
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• 2001

This paper developed the model for electro hydraulic force control system by identification method via ARMAX model. Implementation of Identification is performed on Pin-On-Disk type tribotester. The wear mechanism is an important mechanic property to select a material´s life and a optimum work condition. Pin-on-disk type tribotester is popular wear analysis experimental equipment and its mechanism is that adding a force on a rotating disk to simplify two surface contact´s wear experimental condition. Material´s rotating velocity and eccentricity rotation makes disturbance and it affects adding constant force. To get a high performance of force adding part, DDV(Direct Drive Valve) which has pressure control loop is used. To obtain a tribotester´ s ARMAX model, prediction error method(PEM) is used in case force adding part and rotating part is ...

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.4
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• pp.39-43
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• 2006

A computer-controlled micro tribotester has been developed to investigate the friction and wear characteristics of thin coatings, which can be applied to silicon-based materials. In the developed system, a step motor gives a reciprocating movement and an electromagnet applies a load between a ball and a plate specimen. Test results confirmed that the application of load in the range of $0.03{\sim}1.8N$ and with a sliding speed of $4.44{\sim}7.70mm/s$ was successfully accomplished. Advantages of the developed micro tribotester are: (1) realization of micro load and displacement applicable to micro electromechanical systems(MEMS) using DC motor and electromagnet (2) continuously variable load and reciprocating speed; and (3) high reliability, which allows for unattended use for long periods.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.194-199
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• 1999

For the purpose of improving accuracy in friction and wear test, a hydraulic pin-on-disk type tribotester was developed and its performance was evaluated experimentally. The performance estimation of the tribotesrer was accomplished by comparing both the consistency of the applied normal load and the robustness of the control against the mechanical disturbances with those of the pneumatic and the dead weight loading method respectively. The developed hydraulic pin-on-disk type tribotester showed the better reliability in the performance and the hydraulic loading method provided the more accurate friction coefficient.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.205-211
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• 2000

Friction control is highly desirable for optimization of tribological systems. In this work, the effect of geometric structure of the solid surface on friction is investigated using a Scanning Electron Microscope equipped with a tribotester. Silicon and silicon oxide specimens were used and undulations on the surface were fabricated by mechanical and chemical methods. It is shown that the friction coefficient depends on the relative dimensions of the ball and the width of undualation. By optimizing the geometry of the undulation, friction reduction may be achieved.

• Tribology and Lubricants
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• v.20 no.5
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• pp.237-244
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• 2004

Micro/nano tribological characteristics of PTFE coating films were experimentally studied. PTFE (polytetrafluoroethylene) modified polyethylene and low molecular weight PTFE were used as a coating materials. These films were deposited on Si-wafer (100) by IBAD (ion beam assisted deposition) method. The Ar ion beam sputtering was performed to change the surface topography of films using a hollow cathode ion gun under different Ar ion dose conditions in a vacuum chamber. Micro/nano tribological characteristics, water wetting angles and roughness were measured with a micro tribotester, SPM (scanning probe microscope), contact anglemeter and profilometer, respectively. The durability of the films were measured with macro tribotester. Results showed that the PTFE coating surfaces were converted to hydrophobic. The water contact angle of coated surfaces and surface roughness increased with the coating thickness. Adhesion and friction in micro and nano scale were governed by magnitude of normal load in soft material such as PTFE films. As the increase of sputtering time on low molecular weight PTFE films, the surface roughness was increased and nano adhesion and friction were decreased. The nano tribological characteristics of surfaces are mainly improved by chemical modification such as PTFE coating and given a synergy effect by the physical modification such as topographic modification.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.2
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• pp.219-225
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• 2013

In this study, the tribological characteristics of silver films that were deposited on a glass substrate by electroless plating were investigated. The electroless-plating method has many notable advantages. It is easy and economical to obtain solid films using this coating process, and it can be applied to both nonconducting and conducting substrates. In this study, silver was selected as the electroless-plating material because it is one of the most common materials used as a solid lubricant. The mechanical properties of silver electroless-plated specimens were investigated for various coating conditions. The thickness of the coating could be controlled by varying the electroless-plating time. The properties of the coatings were investigated using AFM, SEM, and a tribotester.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.19-23
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• 2000

Stiction is an undesirable phenomenon that can be encountered often in Micro-Electro Mechanical Systems (MEMS) applications, In order to minimize this effect, Self-Assembled Monolayers (SAM) are commonly used. In this work the frictional characteristics of SAM are investigated using both micro-tribotester and SPM. It was found that the performance of SAM is quite sensitive to coating condition. The experimental results show promise for SAM to be used in sliding applications of micro systems.

• Tribology and Lubricants
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• v.24 no.4
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• pp.190-195
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• 2008

Many researchers have tried to improve the tribological characteristics of lubricant by adding various nano particles in the base lubricant. But the reliability evaluation of the lubricants are rarely performed in its real operation condition. In this study, the physical property and the tribological characteristics of the graphite nano lubricant were evaluated and compared with raw lubricant after thermal degrading. In order to evaluate the tirbological characteristics, the disk-on-disk tribotester was adopted to measure the friction coefficient of the graphite nano lubricants. Also the temperature variations of friction surfaces were measured by the thermocouple installed on the fixed plate in the test chamber of the tribotester. The kinematic viscosity was measured using a capillary viscometer on the temperatures of 40, 60 and $80^{\circ}C$. The results showed that the graphite nano lubricant had lower friction coefficient and less wear on the friction surfaces than raw lubricant. After thermally degrading, the friction coefficients of graphite nano lubricant increased, but the friction coefficients after thermal degradation were still maintained lower than those of raw lubricant.