• Title/Summary/Keyword: Friction properties

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A Study on the Effects of Ultrasonic Nanocrystal Surface Modification (UNSM) and Wonder Process Craft (WPC) Treatments on Tribological Properties of SUJ2 Bearing Steel (SUJ2 베어링 강의 트라이볼로지 특성에 대한 초음파나노표면개질 (UNSM) 및 원더프로세스크래프트 (WPC) 처리 효과 연구)

  • Amanov, A.;Karimbaev, R.;Cho, I.H.;Kim, E.J.
    • Tribology and Lubricants
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    • v.38 no.4
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    • pp.170-178
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    • 2022
  • 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.

Measurement of Mechanical and Physical Properties of Pepper for Particle Behavior Analysis

  • Nam, Ju-Seok;Byun, Jun-Hee;Kim, Tae-Hyeong;Kim, Myoung-Ho;Kim, Dae-Cheol
    • Journal of Biosystems Engineering
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    • v.43 no.3
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    • pp.173-184
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    • 2018
  • Purpose: This study was conducted to investigate the mechanical and physical properties of a Korean red pepper variety for particle behavior analysis. Methods: Poisson's ratio, modulus of elasticity, shear modulus, density, coefficient of restitution, and coefficient of friction were derived for "AR Legend," which is a domestic pepper variety. The modulus of elasticity and Poisson's ratio were measured through a compression test using a texture analyzer. The shear modulus was calculated from the modulus of elasticity and Poisson's ratio. The density was measured using a water pycnometer method. The coefficient of restitution was measured using a collision test, and the static and dynamic friction coefficients were measured using a inclined plane test. Each test was repeated 3-5 times except for density measurement, and the results were analyzed using mean values. Results: Poisson's ratios for the pepper fruit and pepper stem were 0.295 and 0.291, respectively. Elastic moduli of the pepper fruit and pepper stem were $1.152{\times}10^7Pa$ and $3.295{\times}10^7Pa$, respectively, and the shear moduli of the pepper fruit and pepper stem were $4.624{\times}10^6Pa$ and $1.276{\times}10^7Pa$, respectively. The density of the pepper fruit and the pepper stem were $601.8kg/m^3$ and $980.4kg/m^3$, respectively. The restitution coefficients between pepper fruits, pepper stems, a pepper fruit and a pepper stem, a pepper fruit and plastic, and a pepper stem and plastic were 0.383, 0.218, 0.277, 0.399, and 0.148, respectively. The coefficients of static friction between pepper fruits, pepper stems, a pepper fruit and a pepper stem, a pepper fruit and plastic, and a pepper stem and plastic were 0.455, 0.332, 0.306, 0.364, and 0.404, respectively. The coefficients of dynamic friction between a pepper fruit and plastic and a pepper stem and plastic were 0.043 and 0.034, respectively.

A study on the effects of Friction loss of CPVC pipe according to Roughness coefficient in a sprinkler system (스프링클러 시스템에서 조도계수에 따른 CPVC 배관 마찰손실 영향의 연구)

  • Kang, Ung Il
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.11
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    • pp.355-362
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    • 2016
  • The pipe material is selected according to the physical and chemical properties of the fluid flowing within it. Because the fluid used in fire extinguish systems is water, the various foreign substances dissolved in it cause scale to form on the pipe wall and accelerate the corrosion and aging of the pipe itself. This results in an increase in the friction loss and eventually degrades the efficiency of the pump. The use of CPVC (Chlorinated Poly-Vinyl Chloride) pipes was confirmed to reduce the friction loss compared to conventional steel pipes in the design and construction stages. The friction loss was found to be 76.64MPa with a C-value of 120 for the steel pipe and 50.72 MPa with a C-value of 150 for the CPVC pipe in an actual apartment construction environment. It was confirmed that the friction loss was improved by about 34% when using the CPVC pipe. When the steel and CPVC pipes were employed in the construction, the construction costs were 1,585,158 and 931,842 won, respectively. Therefore, it was shown that the construction cost was reduced by about 41%. We investigated the safety of the fire extinguishing system and the improvement in the economic performance due to the reduction in the total installed capacity by studying practical applications in the field.

Analytical Study on Behavior Characteristic of Shear Friction on Reinforced Concrete Shear Wall-Foundation Interface using High-Strength Reinforcing Bar (고강도 전단철근을 사용한 철근콘크리트 전단벽체-기초계면에서의 전단마찰 거동특성에 대한 해석적 연구)

  • Cheon, Ju-Hyun;Lee, Ki-Ho;Baek, Jang-Woon;Park, Hong-Gun;Shin, Hyun-Mock
    • Journal of the Korea Concrete Institute
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    • v.28 no.4
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    • pp.473-480
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    • 2016
  • The purpose of this study is to provide analytical method to reasonably evaluate the complicated failure behaviors of shear friction of reinforced concrete shear wall specimens using grade 500 MPa high-strength bars. A total of 16 test specimens with a variety of variables such as aspect ratio, friction coefficient of interface in construction joint, reinforcement details, reinforcement ratio in each direction, material properties were selected and the analysis was performed by using a non-linear finite element analysis program (RCAHEST) applying the modified shear friction constitutive equation in interface based on the concrete design code (KCI, 2012) and CEB-FIP Model code 2010. The mean and coefficient of variation for maximum load from the experiment and analysis results was predicted 1.04 and 17% respectively and properly evaluated failure mode and overall behavior characteristic until failure occur. Based on the results, the analysis program that was applied modified shear friction constitutive equation is judged as having a relatively high reliability for the analysis results.

Effect of Binders and Additives on Magnetic and Physical Properties of Ultra Fine Metal Particle Tape (자기 테이프용 초미립 자성 철 입자의 분산거동과 전자및 물리특성에 미치는 첨가제의 영향)

  • 김주호;김기호
    • Journal of the Korean Magnetics Society
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    • v.6 no.1
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    • pp.28-35
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    • 1996
  • Dispersion behavior was investigated as functions of species and arrount of addtives, binders, abrasives, lubricants, etc.. Dispersibilityand other various properties were affected by the fuctional groups of binders. Friction coefficient and surface roughness of tape were changed with lubricants, therefore duratility of magnetic tape was varied. As a result of above investigations, we concluded that dispersion behavior of particles was very sensitive for obtaining maximum properties of metal particle tape.

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Corrosion and Sliding Properties of the Nickel-Based Alloys for the Valve Seats Application

  • Honda, Tadashi
    • Corrosion Science and Technology
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    • v.7 no.2
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    • pp.92-98
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    • 2008
  • This paper describes the experiments of the corrosion and the sliding tests of the nickel-based alloys for the gate valve seating materials used at high pressure and temperature. The general corrosion rates and IGC susceptibility are tested in pressurized water at 533 K and 575 K and in Strauss test solution. The sliding tests have been done in pressurized water at 293 k, 473 K and 573 k. The alloys containing above 10% chromium may have the anti-corrosion properties that could be applied to the valve seats for the power plants. The good sliding performance and the good pressure tightness are obtained when the disc specimens that have hardness 500 to 600 Hv combined with the seat specimens that have hardness 250 to 410 Hv containing about 40 percent of iron. The large size gate valves sliding tests have certified the test results. The anti-wear properties of the seat alloy and the anti-IGC susceptibility of the disc alloy could be improved by the addition of silicon and niobium, respectively.

The change in mechanical properties of bond materials for micro-blades with the amount of lubricants (충진 윤활제의 첨가량에 따른 블레이드용 결합제의 기계적 특성)

  • Kim, Song-Hee
    • Journal of Industrial Technology
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    • v.28 no.A
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    • pp.195-198
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    • 2008
  • Graphite and $MoS_2$ were added respectively to the Cu/Sn bond materials of the same composition as a lubricant in order to find out the effect of lubricants on the mechanical properties and the increase in density of the sintered products for microblades. The addition of $MoS_2$ as a lubricant was more beneficial to strength, fracture toughness, and hardness as well as densification than graphite. $MoS_2$ seemed to be more effective in reducing the friction between the metallic powders and die wall during hot pressing process. Due to the better wettability of MoS2 with bond metal alloy, less amount of interfacial defects which is detrimental to mechanical properties use observed.

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The Physical Properties of Solo-spun Fabrics Related to The Yarn Characteristics (Solo-spun 사의 특성에 따른 직물의 물리적 성질)

  • 박수현;오봉효;김승진
    • Textile Coloration and Finishing
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    • v.14 no.1
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    • pp.58-65
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    • 2002
  • This study surveys the physical properties of Solo-spun fabrics related to the characteristics of Solo-spun yarns, which were described in previous reports. For this purposes, 6 kinds of fabrics were woven on the pilot loom. 3 kinds of Solo-spun yarns with the 3 level of twist mutiplier of Nm 1/30 and 3 kinds of conventional ring-spun yarns with the same levels of twist multipliers of the same yarn counts. The fabrics were of 2/2 twill and clear-cut finished. The physical properties were surveyed by means of KES-FB system. Solo-spun fabrics seemed to be stiffer than ring spun fabrics as showing the lower extensibility with higher tensile energy, the higher bending rigidity, and the higher shear rigidity. Solo-spun fabrics showed the lower value in surface friction coefficient and surface roughness. For fabric abrasion tests, Solo-spun fabrics showed the higher pill resistance.

Influence of Particle Properties of Crushed Sand on the Qualities of Concrete (부순모래의 입자특성이 콘크리트의 품질에 미치는 영향)

  • Yoo Seung-Yeup;Sohn Yu-Shin;Lee Seung-Hoon;Lee Gun-Cheol;Yoon Gi-Won;Han Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2005.05a
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    • pp.89-92
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    • 2005
  • This study investigates influence of particle properties of crushed sand on the duality of concrete. The test shows that an increase of fineness modulus(FM) resulted in high slump and air contents, while compressive strength decreased due to decreased adhesion with reduction of surface area. As grain shape become rounder, the slump of concrete increased, due to reduction of internal friction, and increased air contents. The reduction of adhesion by abrasion of surface declined compressive strength during the process of manufacturing crushed sand. Increase of powder contents decreased slump and it also decreased air contents due to the effect of filling air void. In addition. using powder contents increased compressive strength, but could not find any difference of bleeding and tensile strength with particle properties.

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Development of Sintered Oilless Bearing using Fluid-Dynamic Mechanism For High-RPM Application (유체동압 메카니즘을 이용한 고RPM용 소결함유베어링의 개발)

  • 최윤철
    • Journal of Powder Materials
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    • v.4 no.4
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    • pp.275-282
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    • 1997
  • Sintered oilless bearing using fluid-dynamic mechanism for high revolution of over 10,000 rpm was developed by Powder metallurgy Process. Developed bearing was composed of Fe-40-60%Cu of which inner face consisted of six-regular-prominence-and-depression. Inner face has controlled pore size and amount according to application. Jitter and friction properties were tested under assembled conditions with housing and motor. Bearing-own properties and precision were also tested because of demanding for assembled properties. Measurement-skill as well as mould-production-skill were investigated for the precision of bearing. Final precision reached 2 ${\mu}m$ in inner diameter tolerance and 5 ${\mu}m$ in coaxiality under assembled conditions.

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