• Title/Summary/Keyword: The surface hardness

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An effect of load on surface roughness in surface rolling (표면 Rolling시 가압력이 표면 조도에 미치는 영향)

  • 강명순
    • Journal of the korean Society of Automotive Engineers
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    • v.9 no.5
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    • pp.57-65
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    • 1987
  • The surface rolling method which is one of the plastic deformation processes increases the surface roughness with reduction of diameter and hardness. In this study, three NACHI 6000 ZZ bearing were used for surface rolling tool on a mild steel The following results have been obtained with the mild steel. 1) The load is major factor in getting fine surface roughness of roller finishing after grinding The optimal surface roughness of SS41 steel can be obtained at the contact pressure of 210 kgf/cm$^{2}$. 2) At the contact pressure range of 200kgf/cm$^{2}$-210kgf/cm$^{2}$ for optimal surface roughness, The surface hardness increased to Hv200-Hv240 from Hv 125 before surface rolling. 3) Within the diameter variation of 13 .mu.m the surface roughness and the surface hardness were increased, but out of variation of 14.mu.m. The surface roughness become worse and the surface hardness was increased.

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Effect of the bath composition on the surface appearance and the hardness of zinc deposits from the chloride bath (염화물욕에서 아연도금층의 표면외관과 경도에 미치는 욕조성의 영향)

  • 김영근;김명수
    • Journal of the Korean institute of surface engineering
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    • v.33 no.5
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    • pp.339-348
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    • 2000
  • The study was conducted on the effect of bath composition on the surface appearance, the hardness and the crystal orientation of zinc electrodeposits from the chloride bath. (1) The hardness of the zinc electrodeposits from the chloride bath was increased by suppressing mass transfer of zinc through adding the organic additives and the chlorine ion in the electrolyte. (2) The surface whiteness of zinc deposits was decreased due to the change of the preferred orientation from (002) , (103) to (101) , (100) through increasing the organic additives and chlorine ion in the electrolyte. (3) The addition of Cu, Sn, Ni or Co in the chloride bath elevated the hardness of the zinc deposits but darkened the surface whiteness. (4) The optimum condition of the organic additives and the chlorine ion for increasing the hardness of zinc deposits and preventing dark surface ranges 0.3 m1/1 to 0.4 m1/1 and 6.5 mol/1 to 6.8mol/l respectively.

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Surface Hardness Measurement of Anodic Oxide Films on AA2024 based an Ink-Impregnation Method

  • Moon, Sungmo;Rha, Jong-joo
    • Journal of the Korean institute of surface engineering
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    • v.53 no.2
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    • pp.80-86
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    • 2020
  • This paper is concerned with type of imperfections present within the anodic oxide films on AA2024 and surface hardness of the anodic film measured after ink-impregnation. The anodic oxide films were formed for 25 min at 40 mA/㎠ and 15±0.5℃ and 300 rpm of magnet stirring rate in 20% sulfuric acid solution. The ink-impregnation allows clear observations of not only the imperfections within the anodic oxide films but also an indentation mark on the oxide film surface made by a pyramidal-diamond penetrator for the hardness measurement. There were observed four different regions in the anodic oxide films on AA2024 and the surface hardness of the anodic oxide films appeared to be crucially dependent on the type of defects, showing 60~100 Hv on the oxide surface region I with large size black defect, 100~140 Hv on the oxide surface region II with large size grey defect, 140~170 Hv on the oxide surface region III with mall size black and/or grey defects and 170~190 Hv on the oxide surface region IV without defects. The pyramidal indentation marks were observed to be distorted in the regions with a large size black and grey defects, while no distortion of the indentation mark was observed in the regions with small size defects and without visible defects.

A comparison of surface hardness and microstructural characteristics between a type IV stone with and without die hardening treatment, and a polyurethane resin die material (IV형 경석고와 경화처리된 IV형 경석고 그리고 폴리우레탄 수지 치형재의 표면경도와 미세구조 특성의 비교)

  • Lee, Wan-Sun;Kim, Ji-Hwan;Kim, Tae-Suk;Kim, Nam-Sic;Yu, Chin-Ho
    • Journal of Technologic Dentistry
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    • v.34 no.3
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    • pp.227-235
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    • 2012
  • Purpose: This study compared the surface hardness (Vickers) and microstructural characteristics between a type IV stone with and without die hardening treatment, a polyurethane die material. Methods: Materials used were a type IV stone(MG Crystal Rock), two die hardeners (Hardening bath, Epox-it), and a polyurethane resin material(Polyluck). Six specimens per group were prepared according to manufacturer's directions. The prepared specimens were tested by means of hardness test, one-way ANOVA analysis, scanning electron microscopic(SEM) observations and energy dispersive spectroscopic(EDS) analysis. Results: In the hardness test and its statistical analysis, there was no significant difference in the surface hardness between a type IV stone and type IV stone with die hardener coating, type IV stone mixed with an epoxy like material instead of water. In contrast, polyurethane resin material exhibited significantly greater surface hardness than other specimen groups (p<0.05). Conclusion: By considering the results of the hardness test, SEM observations and EDS analysis, although the die hardeners on type IV stone did not show remarkable improvement in surface hardness, the die hardener coating on the surface of type IV stone material did show decrease of microporous and improvement of surface defects.

Effect of surface Treatment on Piston Wear in the Oil Hydraulic Piston Pump

  • Kim, Jong Ki;Park, Kyung Min;Oh, Seok Hyung;Jung, Jae Youn
    • KSTLE International Journal
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    • v.2 no.1
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    • pp.17-21
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    • 2001
  • Surface treatment technologies are frequently used to improve mechanical properties of surface layers of machinery components in many practical situations. Surface hardness of piston in the oil hydraulic piston pumps is very important about wear resistance. To improve hardness, wear resistance of the oil hydraulic axial piston pump, it is needed to know the surface layer characteristics in the sliding contact parts. This paper reports an experimental study on surface treatment characteristics in the piston of the oil hydraulic axial piston pump. We investigated the surface wear of a piston between untreated and nitriding-treated surfaces. We obviously observed that the surface hardness of piston in the oil hydraulic axial piston pump plays an important role to have wear resistance and remain a longer life.

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Characteristics of Hardness and Wear-Resistance of Plasma-Nitrided and Nitrocarburized Carbon Steels (플라즈마질화 및 침질탄화처리한 탄소강의 경도와 내마모특성)

  • Kim, M.K.;Jung, B.H.;Park, H.S.;Lee, B.C.;Shin, S.H.;Lee, J.S.
    • Journal of the Korean Society for Heat Treatment
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    • v.12 no.2
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    • pp.166-173
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    • 1999
  • Commercial carbon steels containing 0.2~0.55 wt.----C were plasma-nitrided or plasma nitrocarburized at $550^{\circ}C$ for 21.6Ks using $H_2-N_2$ or $H_2-N_2$-CO mixed gas respectively. The characteristics of hardening and wear-resistance of each treatment were studied and compared. And also microstructure of nitrided layer and nitrides formed in compound layer near surface were studied. All plasma-nitrided steels investigated showed remarkable increase of surface hardness with the increase of carbon content. But nitrocarburized steels resulted in higher surface-hardness than plasma-nitrided steels, which means that nitrocarburized has higher surface-hardening effect. Plasma-nitrided steels showed hardness increase in through-thickness direction near surface. And also nitrocarburized steels showed similar hardness distribution in through-thickness direction to that of plasma-nitrided steel. However, nitrocarburized steels had higher cross-sectional maximum-hardness than plasma-nitrided steels as much as 100Hv. Wear test showed that the amount of specific wear was reduced by both plasma-nitriding and nitrocarburized, showing that the amount of specific wear was not related to the hardness. But non-treated specimen showed that the amount of specific wear was related to the hardness.

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Evaluation of the Vickers hardness on denture acrylic resins by glaze color (글레이즈 컬러를 적용한 의치상 레진의 비커스 경도 평가)

  • Yong-Woon Im
    • Journal of Technologic Dentistry
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    • v.44 no.4
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    • pp.111-117
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    • 2022
  • Purpose: This study was conducted to compare the Vickers hardness on the denture acrylic resins using the glaze color system. Methods: The specimens (20×2 mm) were prepared by mixing according to the manufacturer's protocols through thermal polymerization and self-polymerization. The surface roughness was measured using a testing machine after water-soaking for 48 hours. For the Vickers hardness measurement, the completed specimen was soaked in water for 48 hours and then applied at 200 gf for 30 seconds. Was the specimen immersed after being soaked in water for 48 hours at temperatures of 5℃ and 55℃, respectively, for 30 seconds for the thermos-cycling treatment, and it was carried out 5,000 times. Results: Surface roughness was higher in the more glazing group than in the control group. A significant difference was observed in all groups, except for the Retec Don 2000 and Luciton 199 groups (p<0.05). As a result of measuring the Vickers hardness, the treatment by glaze color showed slightly lower but the thermo-cycling treatment group appeared higher than control group in all. Conclusion: Therefore, the glaze color was found to affect the surface roughness and showed a significant difference. The surface glaze color showed a very high Vickers hardness after the thermo-cycling treatment, indicating that the surface-strengthening effect is greater in the oral environment.

Influence of Deposition Parameters on Film Hardness for Newly Synthesized BON Thin Film by Low Frequency R.F. PEMOCVD

  • G.C. Chen;J.-H. Boo;Kim, Y.J.;J.G. Han
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2001.06a
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    • pp.73-73
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    • 2001
  • Boron-containing materials have several excellent properties, such as superlnardness, insulation and non-Rinear optical property. Recently, oxynitride compounds, such as Si(ON), Ti(ON), became the promising materials applied in diffusion barrier layer and solar cell. With the expectation of obtaining the hybrid property, we have firstly grown the BON thin film by radio frequency (R.F.) plasma enhanced metalorganic chemical vapm deposition (PEMOCVD) with 100 kHz frequency and trimethyl borate precursor. The plasma source gases used in this study were Ar and $H_2$, and two kinds of nhmgen source gases, $N_2$ and <$NH_3$, were also employed. The as-grown films were characterized by XPS, IR, SEM and Knoop microlhardness tester. The relationship between the films hardness and the growth rate indicated that the hardness of the film was dependent on several factors such as nitrogen source gas, substrate temperature and film thickness due to the variation of the composition and the structure of the film. Both nitrogen and carbon content could raise the film hardness, on which nitrogen content did stronger effect than carbon. The smooth morphology and continuous structure was benefit of obtaining high hardness. The maximum hardness of BON film was about 10 GPa.

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An Effect of surface treatment on a Protection Ballistic Limits in armor material (표면처리가 장갑재료의 방호한계에 미치는 영향)

  • 손세원;김희재;이두성;홍성희;유명재
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.12
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    • pp.126-134
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    • 2003
  • In order to investigate the effect of surface treatment in Aluminium alloy and Titanium alloy which are used to armor material during ballistic impact, a ballistic testing was conducted. Anodizing was used to achieve higher surface hardness of Aluminium alloy and Iron plating in PVD(Physical Vapor Deposition) method was used to achieve higher surface hardness of Titanium alloy. Surface hardness test were conducted using a Micro victor's hardness tester. Ballistic resistance of these materials was measured by protection ballistic limit(V-50), a statical velocity with 50% probability penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are respectfully observed from the results of V-50 test and Projectile Through Plates (PTP) test at velocities greater than V-50. PTP tests were conducted with 0$^{\circ}$obliquity at room temperature using 5.56mm ball projectile. V-50 tests were conducted with 0$^{\circ}$obliquity at room temperature with projectiles that were able to achieve near or complete penetration during PTP tests. Surface hardness, resistance to penetration. and penetration modes of surface treated alloy laminates are compared to those of surface non-treated alloy laminates. A high speed photography was used to analyze the dynamic perforation phenomena of the test materials.

Surface Hardness Improvement of Larch Wood Using Thermal-Compression (열압밀화를 이용한 낙엽송의 표면경도 개선)

  • Hwang, Sung-Wook;Park, Sang-Bum;Suh, Jin-Suk;Kim, Jong-In;Hong, Seong-Cheol;Lee, Won-Hee
    • Journal of the Korea Furniture Society
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    • v.23 no.4
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    • pp.460-466
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    • 2012
  • This study was conducted to investigate the surface hardness of thermally-compressed larch wood by compression set and temperature. The surface hardness of thermally-compressed larch wood increased with increasing compression set and temperature. For compression set 60%, the specific gravity was increased as 0.93. However, the surface hardness was lower value as 31.1 N/$mm^2$ compared with a similar specific gravity of the tropical timber. For density profile, less than compression set 40%, compression was observed mainly surface area. On the other hand, more than 50%, density profile variation was reduced by compression of central part. Results of this study indicate that thermally-compressed larch wood can be replace some imported hardwoods such as oak or cherry. However, thermally-compressed larch wood was difficult to replace the tropical timber being imported in terms of surface hardness.

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