• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.6 no.2
• /
• pp.76-82
• /
• 1997

The discrimination of flaw shape and sizing is very important subject in the material evaluation for semiconductor and new materials. The aim of this paper is to investigate the spectrum analysis of artificial defect signal captured from steel ball embedded in the resin. The results show that it can be evaluated quantitatively the size of artificial defect, from the amplitude variation of same frequency if the probe with same diameter and focal length is used. Comparing with the amplitude variation of the high frequency component and low frequency component obtained from the distance of defect center position, it can be estimated steel ball and flat bottm defect.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.23 no.1
• /
• pp.62-66
• /
• 2015

In this paper, a fretting testing machine is developed using ball-on-flat test apparatus. Precise micro-slip motion is produced by a linear stage. A relative displacement between a ball and a flat specimen is measured with a laser displacement sensor. Dry friction tests are conducted with AISI 52100 steel balls and cold-rolled high strength steel plates at room temperature and ambient humidity. The evolution of the kinetic friction coefficient is determined. Comparison between measured friction coefficients and those found in the literature is then carried out. Fretting tests with an electro-deposited coating are employed at an amplitude of 0.05 mm. Slip regime is identified with slip ratio. It is demonstrated that a developed testing machine allows determining the friction coefficient under fretting condition.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.2 no.6
• /
• pp.66-75
• /
• 1994

In this paper, the effects of temperature change on the impact damages of CF/PEEK laminates are experimentally investigated. Composite laminates used in this experiment are CF/PEEK orthotropic laminated plates, which have two-interfaces$[0^{\circ}_4/90^{\circ}_4]_{9+} A steel ball launched by the air gun collides against CFRP laminates to generate impact damage. The delamination damages are oberved by a scanning acoustic microscope. And various relations are experimentally observed including the impact energy vs. delamination area, the specimen temperature vs. transverse crack, and the impact energy vs. residual bending strength of carbon fiber peek composite laminates subjected to FOD(Foreign Object Damage) under high temperatures.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.06a
• /
• pp.401-405
• /
• 2001

The effects of oxide layer formed on TiN coated ball and counter-body have been investigated from the frictional point of view during sliding tests. AISI52100 steel ball was used for the substrate of coated specimens. Two types of coated specimens were prepared by depositing TiN coating with 1 and 4$\mu\textrm{m}$ in coating thickness. AISI1045 steel was used for the disk type counter-body. To investigate the effect of oxide layer on the contact parts of two materials, the tests were performed both in ambient for forming oxide layer on the contact parts and in nitrogen environment to avoid oxidation.

• Tribology and Lubricants
• /
• v.39 no.6
• /
• pp.228-234
• /
• 2023

In this study, reciprocating wear tests are performed on AISI 52100 bearing steel to investigate its tribological behavior in a hexagonal boron nitride (h-BN) water solution. The h-BN-based aqueous lubricant is prepared using an atoxic procedure called ultrasonic sonication in pure water. Ball-on-flat reciprocating sliding experiments are conducted, where the ball is slewed on a fixed flat at 50-㎛ displacement. The lubricating behavior of h-BN is compared with that of deionized (DI) water. Results show that the friction coefficient is higher in h-BN testing than that in DI tests, but the results are equalized as the friction coefficient reaches a stable level. Scanning electron microscopic images reveal significant material loss in the center and mild abrasion on the edge of the wear scar in h-BN tests. However, these effects are minor in DI water situations. The results of energy-dispersive X-ray spectroscopy show that considerable oxidation occurs in the central zone of the wear scar in h-BN cases with strong adhesion and material removal. These findings reveal the importance of determining ideal circumstances that can tolerate material friction and wear.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2002.10a
• /
• pp.301.1-301
• /
• 2002

• 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.

• Corrosion Science and Technology
• /
• v.5 no.2
• /
• pp.52-61
• /
• 2006

Recently, much of the current development in surface modification engineering are focused on multilayered coatings. Multilayered coatings have the potential to improve the tribological properties. Four different multilayered coatings were deposited on AISI D2 steel. The prepared samples are designed as $WC-Ti_{0.6}Al_{0.4}N$, $WC-Ti_{0.53}Al_{0.47}N$, $WC-Ti_{0.5}Al_{0.5}N$ and $WC-Ti_{0.43}Al_{0.57}N$. The multilayered coatings were investigated with respect to coating surface and cross-sectional morphology, roughness, adhesion, hardness, porosity and tribological behavior. Especially, wear tests of four multilayered coatings were performed by using a ball-on-disc configuration with a linear sliding speed of 0.017 m/sec, 5.38 N load. The tests were carried out at room temperature in air by employing AISI 52100 steel ball ($H_R=66$) having a diameter of 10 mm. The surface morphology, and topography of the wear scars of samples and balls have been determined by using scanning electron spectroscopy (SEM). Results have showed an improved wear resistance of the $WC-Ti_{1-x}Al_xN$ coatings with increasing of Al concentration. $WC-Ti_{0.43}Al_{0.57}N$ coating with the lower surface roughness and porosity with good adhesion enhanced wear resistance.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2001.11a
• /
• pp.31-32
• /
• 2001

Recently, many of the current development in surface modification engineering are focused on multilayered coatings. Multilayered coatings have the potential to improve the tribological and corrosion properties of tools and components. By using cathodic arc deposition, $WC-Ti_{1-x}Al_xN$ multilayers were deposited on steel substrates. Wear tests of four multiplayer coatings were performed using a ball-on-disc configuration with a linear sliding speed of 0.1m/s, 5N load. The tests were carried out at room temperature in airby employing AISI 52100 steel ball ($H_v=848N$) of 11mm in diameter. Electrochemical tests were performed using the potentiodynamic and electrochemical impedance spectroscopy (EIS) measurements. The surface morphology and topography of the wear scars of tribo-element and the corroded specimen have been determined by using scanning electron spectroscopy (SEM). Also, wear mechanism was determined by using SEM coupled with EDS. Results have showed an improved wear resistance and corrosion resistance of the $WC-Ti_{1-x}Al_xN$ coatings.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.22 no.3
• /
• pp.529-539
• /
• 1998

A quantitative study of impact damage of ${Al_2}}O_3}-TiO_2$ plasma coated soda-lime glasses was carried out and compared with that of the uncoated smooth glass specimen. The shape of cracks by the impact of steel ball was observed by stereo-microscope and the decrease of the bending strength due to the impact of steel ball was measured through the 4-point bending test. At the low velocity, cone cracks were occurred. As the impact velocity increases, initial lateral cracks were propagated on the slanting surface of a cone crack, and radial cracks were generated at the crushed site. When the impact velocity of steel ball exceeds the critical velocity, the contact site of specimen was crushed due to plastic deformation and then radial and lateral cracks were largely grown. Crack length of coated specimens was smaller than that of uncoated smooth specimen due to the effect of coating layer on the substrate surface. According to impact velocity, the bending strength of coated specimens had no significant difference, compared with that of the uncoated smooth specimen. But this represents that the bending strength of coated specimens was increased, considering the effect of sand blasting damage which was performed to increase the adhesion force of coating layer.