SUJ2 베어링 강의 트라이볼로지 특성에 대한 초음파나노표면개질 (UNSM) 및 원더프로세스크래프트 (WPC) 처리 효과 연구

AMANOVAUEZHAN,카림바예프 루슬란,조인호,김응주 한국트라이볼로지학회 2022 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.38 No.4

Mechanical surface treatment is an excellent approach widely used to modulate and improve the performance and service life of bearings, gears, and frictional joints. The main purpose of this study is to investigate and compare the effect of ultrasonic nanocrystal surface modification (UNSM) and wonder process craft (WPC) on the surface and tribological properties of SUJ2 bearing steel. The surface roughness and hardness of the untreated and treated (UNSM- and WPC-treated) specimens were measured and compared. Their tribological properties were evaluated using a micro-tribometer under grease-lubricated and dry conditions against itself. Surface hardness measurement results revealed that both the UNSM- and WPC-treated specimens had a higher hardness than that of the untreated specimen. The surface roughness of the untreated specimen was reduced after UNSM and WPC treatments. Abrasive wear mode was observed on the surface of the specimens worn under grease-lubricated conditions, while adhesive wear mode was found on the surface of the specimens worn in dry conditions. According to the tribological test results, the friction coefficient and wear rate of the untreated specimens were reduced by the application of both the UNSM and WPC treatments under grease-lubricated and dry conditions.

Effect of combined shot peening and ultrasonic nanocrystal surface modification processes on the fatigue performance of AISI 304

Amanov, Auezhan,Karimbaev, Ruslan,Maleki, Erfan,Unal, Okan,Pyun, Young-Sik,Amanov, Tileubay Elsevier 2019 Surface & coatings technology Vol.358 No.-

<P><B>Abstract</B></P> <P>In this study, the fatigue performance of AISI 304 subjected to shot peening (SP), ultrasonic nanocrystal surface modification (UNSM) and the combination of SP + UNSM processes was systematically assessed by rotary bending fatigue (RBF) tester at different stress levels. The purpose of combining SP and UNSM processes is to find out whether SP following UNSM process can further improve the fatigue life of AISI 304 in comparison with the SP and UNSM processes alone. Interestingly, the fatigue strength of AISI 304 was deteriorated by the combination of SP + UNSM processes in comparison with the UNSM process alone, but the combination of SP + UNSM processes demonstrated a higher fatigue strength in comparison with the SP process alone.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SP, UNSM and SP + UNSM processes were applied to AISI 304. </LI> <LI> UNSM process exhibited the highest surface hardness. </LI> <LI> UNSM process induced the highest compressive residual stress. </LI> <LI> SP + UNSM process exhibited better results than SP process. </LI> <LI> UNSM process demonstrated the longest fatigue life than SP and SP + UNSM processes. </LI> </UL> </P>

A Preliminary Study on Hybrid Use of Thermal Spray Coating and Ultrasonic Nanocrystalline Surface Modification Technique on the Tribological Properties of Yttria-Stabilized Zirconia Coating

Amanov, Auezhan,Pyun, Young-Sik ASME International 2016 Journal of tribology Vol.138 No.3

<P>An ultrasonic nanocrystal surface modification (UNSM) technique was applied to a thermally sprayed yttria-stabilized zirconia (YSZ) ceramic coating deposited onto a hot tool steel substrate to improve the mechanical and tribological properties. The friction test results showed that the UNSM-treated coating had a smoother surface, a lower friction, and a higher resistance to wear compared to that of the as-sprayed coating. It was also demonstrated that the UNSM technique improved the adhesion behavior of the coating by about 24%. Hence, it was found that a hybrid use of thermal spray coating (TSC) and UNSM technique is a meaningful way to bring together synergy effect of two emerging surface technologies in terms of tribology.</P>

Low friction and high strength of 316L stainless steel tubing for biomedical applications

Amanov, Auezhan,Lee, Soo–,Wohn,Pyun, Young–,Sik Elsevier 2017 Materials Science and Engineering C Vol.71 No.-

<P>We propose herein a nondestructive surface modification technique called ultrasonic nanocrystalline surface modification (UNSM) to increase the strength and to improve the tribological performance of 316L stainless steel (SS) tubing. Nanocrystallization along nearly the complete tube thickness of 200 pm was achieved by UNSM technique that was confirmed by electron backscatter diffraction (EBSD). Nano-hardness of the untreated and UNSM-treated specimens was measured using a nanoindentation. Results revealed that a substantial increase in hardness was obtained for the UNSM-treated specimen that may be attributed to the nanocrystallization and refined grains. Stress-straip behavior of the untreated and UNSM-treated specimens was assessed by a 3-point bending test. It was found that the UNSM-treated specimen exhibited a much higher strength than that of the untreated specimen. In addition, the tribological behavior of the untreated and UNSM-treated specimens with an outer diameter (OD) of 1.6 mm and an inner diameter (ID) of 1.2 mm was investigated using a cylinder-on-cylinder (crossed tubes of equal radius) tribo-tester against itself under dry conditions at ambient temperature. The friction coefficient and wear resistance of the UNSM-treated specimen were remarkably improved compared to that of the untreated specimen. The significant increase in hardness after UNSM treatment is responsible for the improved friction coefficient and wear resistance of the tubing. Thus, the UNSM technique was found to be beneficial to improving the mechanical and tribological properties of 316L SS tubing for various potential biomedical applications, in particular for coronary artery stents. (C) 2016 Elsevier B.V. All rights reserved.</P>

Improvement in Fretting Wear Damage of Annealed Inconel 718 Alloy at a Temperature of 200 °C

Amanov, Auezhan,Kim, Jun-Hyong,Pyun, Young-Sik American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.12

<P>In this study, a nanocrystalline surface layer with a thickness of about 50 mu m was produced at the top surface of annealed Inconel 718 alloy by ultrasonic nanocrystalline surface modification (UNSM) technique. The presence of nanocrystalline structure and plastically deformed layer at the top surface were characterized by electron backscatter diffraction (EBSD) and scanning electron microscopy (SEM), respectively. The hardness of the specimens before and after UNSM treatment was measured using a micro-hardness tester at a load of 300 gf for dwell time of 30 s. The effectiveness of produced nanocrystalline surface layeron the fretting wear damage was investigated at a temperature of 200 degrees C under dry fretting conditions against SAE52100 bearing steel. Results revealed that the UNSM treatment enhanced the fretting wear resistance of annealed Inconel 718 alloy compared to the untreated specimen, which may be attributed to the presence of nanocrystalline structure and deformed layer, induced compressive residual stress and increased hardness. In addition, a fretting wear mechanism of the untreated and UNSM-treated specimens was discussed.</P>

Wear and Chattering Characteristics of Rail Materials by Ultrasonic Nanocrystal Surface Modification

장세기,편영식,AMANOVAUEZHAN 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

Stick-slip wear, sliding wear, rolling contact wear, fatigue failure and chattering are persistent problems of a wheel-rail interface, especially at corner track. Generally, high strength alloy and heat-treated rail were used at corner track in order to improve the service life and chattering level, but these targets still remain as unceasing challenge subject. Ultrasonic nanocrystal surface modification (UNSM) was applied to rail materials with the aim of replacing with heat treatment and/or improving the service life of rails. In this study, the mechanical and wear properties of the untreated and UNSM-treated specimens which were prepared from normal and heat treated rails. Friction and wear tests were performed to measure the friction coefficient and the amount of wear. Results revealed that the wear performance of the UNSM-treated specimens was improved due to the increased hardness and induced compressive residual stress after UNSM treatment. The wear mechanism of the UNSM-treated specimens was explained with the changes in surface properties of rail materials.

니들 롤러 베어링의 피로 수명 향상에 대한 연구

다리스렝 스르멩닥와,AMANOVAUEZHAN,편영식 한국트라이볼로지학회 2019 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.35 No.4

Through this study, we investigate the effects of ultrasonic nanocrystal surface modification (UNSM) technology on the fatigue life of needle roller bearings. The fatigue life of untreated and UNSM-treated needle roller bearings is evaluated using a roller fatigue tester at various contact stress levels under oil-lubricated conditions. We can ascertain that the fatigue life of an UNSM-treated needle roller bearing was extended by approximately 34.3% in comparison with an untreated one, where the effectiveness of UNSM technology diminishes with increasing contact stress. The surface roughness and surface hardness of needle roller bearings before and after being treated by UNSM technology are compared and discussed to understand the role of UNSM technology in improving the fatigue life of needle roller bearings. In addition, a fractograph of the damaged bearings is observed using a scanning electron microscopy to shed light on the fracture mechanisms of bearings under different contact stress levels. We can therefore conclude that the application of UNSM technology to the needle roller bearings improves the fatigue life by reducing the friction coefficient and increasing the wear resistance; this may be attributed to a reduction in surface roughness from 0.5 to 0.149 μm and an increase in surface hardness from 58 to 62 HRc.

분말 야금에 의해 소결된 강철의 트라이볼로지 특성 향상

최세이미,카림바예프 루슬란,편영식,AMANOVAUEZHAN 한국트라이볼로지학회 2020 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.36 No.4

Materials manufactured by powder metallurgy (PM) are widely used in various applications such as water pump, shock absorber, and airplane components due to the reduction in the cost and weight. In this study, tribological properties of carbon steel subjected by surface treatment were investigated. The main purpose is to increase the strength and improve the tribological properties by reducing pores that formed by PM. Moreover, the surface treatment was carried out at room and high temperatures (RT and HT). The surface roughness of the untreated (NON) and treated (AFTER) samples was measured. It was found that the surface roughness was reduced after both the RT AFTER and HT AFTER compared to RT NON sample. The tribological properties of the samples were performed against bearing steel ball under dry conditions. The friction coefficient of the RT NON samples was reduced by 22% and 56% RT AFTER and HT AFTER, respectively. The wear volume of the RT NON sample was also reduced by 43% and 87% RT AFTER and HT AFTER, respectively. Tribocorrosion tests were also performed and it was found that the surface of the RT AFTER, HT AFTER samples was less corroded compared to RT NON sample. The HT AFTER sample demonstrated a relatively higher corrosion potential in comparison with the RT AFTER samples. Hence, it was confirmed that after surface modification the surface roughness and hardness of the samples were significantly improved resulting in improvement in tribological and tribocorrosion behaviors of PM carbon steel.

SM45C재의 UNSM 처리에 의한 트라이볼러지 특성 변화

심현보,서창민,서민수,AMANOVAUEZHAN,편영식 한국해양공학회 2018 韓國海洋工學會誌 Vol.32 No.6

The following results were obtained from a series of studies to accumulate data to reduce the coefficient of friction for press dies by performing tribological tests before and after the UNSM treatment of SM45C. The UNSM-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those for untreated materials. When loads of 5 N, 7.5 N, and 10 N were applied to the untreated material of SM45C, the coefficient of friction was approximately 0.76–0.78. With the large specimen, a value of 0.72–0.78 was maintained at a load of 50 N despite the differences in the size of the wear specimen and working load. Tribological tests of large specimens of SM45C treated with UNSM under tribological conditions of 100 N and 50 N showed that the frictional coefficient and time constant stably converged between 0.7 and 0.8. The friction coefficients of the small specimens treated with UNSM showed values between 0.78 and 0.75 under 5 N, 7.5 N, and 10 N. The friction coefficients of the SM45C treated with UNSM were comparable to each other.

Tribological Performance of Ni-Cr Composite Coating Sprayed onto AISI 4340 (SNCM439) Steel by High Velocity Oxygen Fuel

우마로프 라크마트천,편영식,AMANOVAUEZHAN 한국트라이볼로지학회 2018 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.34 No.6

In this study, we spray a Ni-Cr composite powder onto AISI 4340 steel using the high velocity oxygen fuel method. We subsequently subject the Ni-Cr coating (as-sprayed) to ultrasonic nanocrystal surface modification (UNSM) process to improve the tribological performance. This study aims at increasing the wear resistance and durability of the Ni-Cr coating by altering the surface integrity and microstructure via the UNSM process. The UNSM process reduces the surface roughness of the as-sprayed coating by about 64%, which is explained by observing the elimination of high peaks and valleys and filling up micro-pores. Furthermore, a change in the microstructure of the coating due to continuous high-frequency strikes to the surface by a tip can lead to an increase in hardness from about 48 to 60 HRC. Furthermore, we investigate the characterization of the friction and wear behavior of Ni-Cr coating by a ball-on-disc tribometer in the dry conditions. We determine that after the UNSM process, there is a significant reduction in the friction coefficient of the as-sprayed coating from approximately 1.1 to 0.75. This is owing to the increased hardness and smoothed surface roughness. In addition, we investigate the surface morphology and wear track of the coatings before and after the UNSM process using a scanning electron microscope, energy dispersive spectrometer, and three-dimensional laser scanning microscope. We observe that the wear track of the Ni-Cr coating after the UNSM process is lower than that of the as-sprayed one. Thus, we confirm that the UNSM process has a significant influence on the improvement of the tribological performance of the Ni-Cr composite coating.