• Title/Summary/Keyword: Scratch test

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Using scratch test to evaluate cohesive bond strength of Mo composite coating

  • Koiprasert, Hathaipat;Thaiwatthana, Sirinee;Sheppard, Panadda
    • International Journal of Advanced Culture Technology
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    • v.3 no.2
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    • pp.34-41
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    • 2015
  • Bonding strength of a thermal sprayed coating is difficult to measure using a conventional pull-off test method. Scratch test is a potential alternative testing method. An adhesive and a cohesive bond strength of the coating can be measured by the pull-off test while the scratch test performed on the cross-section of the thermal sprayed coating can only demonstrate the cohesive bond strength of the coating. Nevertheless, it is still beneficial to perform the scratch testing on the cross-section of the coating for the sake of comparison thus providing an alternative to the pull-off test. The scratch test method can reduce testing time and cost in the long run due to a significant cost reduction in consumables and energy and time saving from the curing step of the glue used in the pull-off test. This research investigates the possibility of using the scratch test to measure the cohesive bond strength of Mo/NiCrBSi composite coating. The results from the pull-off test and the scratch test indicate that the cohesive bond strengths of the Mo composite coating show similar trend and that the cohesive bond strength are increased when increasing NiCrBSi content.

Finite Element Analysis of Nano Deformation for Hyper-fine Pattern Fabrication by Application of Nano-scratch Process (나노스크래치 공정을 이용하여 극미세 패턴을 제작하기 위한 나노 변형의 유한요소해석)

  • 이정우;강충길;윤성원
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.3
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    • pp.139-146
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    • 2004
  • In this study, to achieve the optimal conditions for mechanical hyper-fine pattern fabrication process, deformation behavior of the materials during indentation scratch test was studied with numerical method by ABAQUS S/W. Brittle materials (Si, Pyrex glass 7740) were used as specimens, and forming conditions to reduce the elastic recovery and pile-up were proposed. The indenter was modeled as a rigid surface. Minimum mesh sizes of specimens are 1-l0nm. Variables of the nanoindentation scratch test analysis are scratching speed, scratching load, tip radius and tip geometry. The nano-indentation scratch tests were performed by using the Berkovich pyramidal diamond indenter. Comparison between the experimental data and numerical result demonstrated that the FEM approach can be a good model of the nanoindentation scratch test. The result of the investigation will be applied to the fabrication of the hyper-fine pattern.

Characteristics and Assessment of Printer Toner Adhesion (프린터 토너의 점착력 특성 및 평가 기법)

  • Lee, Jung-Eun;Kim, Kwang-Il;Kim, Hyun-Joon;Kim, Dae-Eun
    • Transactions of the Society of Information Storage Systems
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    • v.5 no.2
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    • pp.82-88
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    • 2009
  • Understanding the adhesion behavior and characteristics of toner film is required to achieve image and text printing with high quality resolution. Toner can be considered as a thin film coating on a media such as paper or polymer film. Quantitative measurement of adhesion characteristics of the thin film is important to assess the reliability of the system. In this work the main objective was to investigate the adhesion characteristic between the toner and the media by ramp loading scratch test method. The scratch test may be used to obtain quantitative information about the adhesion of the film to the substrate. In the scratch test a diamond tip was used to scratch the surface of the toner film under an increasing normal load until the toner detached or fractured. The critical load (LC) was obtained from the experimental results. Also, the relationship between the critical load and the adhesive strength of the interface between the substrate and the toner was obtained by measuring the normal and tangential forces during the scratch test. Finally, theoretical analysis of the toner scratch characteristics was performed based on Benjamin and Weaver theory, Plowing model, and Laugier model.

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The Research of Scratch Characteristics For Non-Vinyl Pre-Coated Metal Sheet (Non-Vinyl Pre-Coated Metal의 스크래치 특성에 관한 연구)

  • 김동환;조형근;김병민
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.874-877
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    • 2000
  • Pre-coated sheet materials are a cost-effective and environmentally attractive alternative to conventional sheet materials coated after forming. At present but the high scratch sensitivity of coating used for pre-coated metal sheet is a major limitation to use of these materials. Because of high scratch sensitivity, products made by pre-coated metal sheet are not formed by conventional design method. This study has been performed to investigate scratch characteristic of non-vinyl pre-coated metal (PCM) sheet. Using the simple U-bending test equipment, three non-vinyls PCM's were tested. This paper provides the results of bending tests showing the influence of sheet surface texture, tool material and process conditions. It was found that the influence of punch, die clearance and tool material had an effect upon the scratch characteristic.

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Evaluation of Failure Modes and Adhesion of DLC Films by Scratch Test (스크래치 시험을 통한 DLC 박막 파손과 밀착 특성 평가)

  • Kim, Ju Hee;Park, Chanhyung;Ahn, Hyo Sok
    • Tribology and Lubricants
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    • v.33 no.4
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    • pp.127-133
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    • 2017
  • In order to characterize the adhesive properties and failure mechanisms of diamond-like carbon (DLC) films of two different thicknesses (130 nm and $1.2{\mu}m$), deposited by plasma-enhanced chemical vapor deposition on a Si substrate, scratch testing with a micro-indenter ($12.5{\mu}m$ tip radius) was performed under a linearly increasing load. These scratch tests were conducted under the same test conditions for both films. The critical load of each film was estimated from the scratch test results, based on a sharp increase in the coefficient of friction and a clear distinction of failure modes. The critical load was the basis for evaluating the adhesion strength of the films, and the $1.2{\mu}m-thick$ DLC film had superior adhesion strength. For better understanding of the failure modes, the following analyses were conducted: friction behavior and scratch tracks analysis using scanning electron microscopy, energy-dispersive spectroscopy, and 3-D profilometry. The scratch test results showed that failure modes were related to the thickness of the films. The 130 nm-thick DLC film underwent cohesive failure modes (cracks and chipping) before reaching to a gross failure stage. On the other hand, the thicker DLC film ($1.2{\mu}m-thick$) did not exhibit micro cracks before a sudden gross failure of the film together with the evidence of cracking and chipping of the Si substrate.

Study on Scratch Characteristics of HDD Media and ZnO Thin Films by Ramp Loading Scratch Method (Ramp Loading Scratch 방법을 이용한 상용 HDD Media와 ZnO박막소재의 Scratch 특성에 관한 연구)

  • Kim, Dae-Eun;Lee, Jung-Eun;Lin, LiYu
    • Tribology and Lubricants
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    • v.24 no.2
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    • pp.77-81
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    • 2008
  • In this work, ramp loading scratch method was used to evaluate the scratch characteristics of HDD media and ZnO thin films. Commercially available HDD media and ZnO thin films grown on silicon(100) substrate by sol-gel method were used. As for the ZnO films, the effects of annealing temperature after the film deposition process were also investigated. A custom built scratch tester was used to scratch the specimen under a ramp loading condition. The scratch track formed by ramp loading was measured by optical microscope and Atomic Force Microscopy (AFM). The wear depth and width were used to assess the scratch characteristics of the HDD Media and ZnO thin films. The results showed that ZnO film annealed at $800^{\circ}C$ had the best scratch resistance property. Also, the HDD media showed overall better scratch resistance than the ZnO films.

Quantitative Evaluation of Scratch Related Tool Life for Stamping of UHSS Using Pin-on-Flat Surface Test (Pin-on-Flat Surface Test를 이용한 초고장력강판 스탬핑 금형의 정량적 스크래치 수명평가)

  • Choi, H.S.;Kim, S.G.;Kim, B.M.;Ko, D.C.
    • Transactions of Materials Processing
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    • v.22 no.2
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    • pp.86-92
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    • 2013
  • When stamping ultra-high-strength steel (UHSS), the phenomenon of galling, which corresponds to a transfer of material from the sheet to the tool surface, occurs because of the high contact pressure between tool and workpiece. Galling leads to increased friction, unstable interface conditions, scratches on the sheet and the tool surfaces and, eventually, premature tool surface failures. Therefore, a simple and accurate evaluation method for tool scratching is necessary for the selection of tool material and coating, as well as for a better optimization of process conditions such as blank holder force and die radius. In this study, the pin-on-disc (PODT) and pin-on-flat surface (POFST) tests are conducted to quantitatively evaluate scratch-related tool life for stamping of UHSS. The variation of the friction coefficient is used as an indicator of scratch resulted from galling. The U-channel ironing test (UCIT) is performed in order to validate the results of the friction tests. This study shows that the POFST test provides a good quantitative estimation of tool life based on the occurrence of scratch.

Processability study of dental zirconia block using scratch test (스크래치 시험을 이용한 치과용 지르코니아 블록의 가공성 연구)

  • Kim, Yung-Hoon
    • Journal of Technologic Dentistry
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    • v.40 no.1
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    • pp.27-32
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    • 2018
  • Purpose: This study was performed to investigate processability of the dental zirconia block. Most of the CAD/CAM zirconia restorations utilize the partially sintered blocks, which are sintered at a temperature lower than $1100^{\circ}C$. Methods: Partially sintered zirconia samples were prepared $40{\times}30{\times}10mm$ and surface treatment by #2000 sandpaper. Scratch hardness was determined by the procedure of ASTM G171-03 using a scratch hardness tester(KS TECH, Korea) equipped with a real time load detector to measure tangential force during scratching. The scratch rate was 30 mm/min. Results: Scratch hardness(Hs) increases steeply with increase in the loads. The highest Hs was sampl 1.42 GPa and lowest was sample 0.42 GPa. Conclusion : The machinability of partially sintered CAD/CAM zirconia blocks can be optivized by manipulation of Hs.

A Study on Friction and Wear of TiN Film for the Wear-life Prediction (마모수명평가를 위한 TiN 경질박막의 마찰 및 마모특성에 관한 연구)

  • 정기훈;이영제
    • Tribology and Lubricants
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    • v.13 no.3
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    • pp.28-32
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    • 1997
  • Indentation, scratch and sliding tests were carried out in this paper to predict the critical loads and the failure modes of TiN-coated specimen. The test specimens were S20C steels with three different substrate hardness, roughness and coating thickness. The scratch test shows that the coating thickness has more dominant effect on the critical load of coated disk than the hardness and the roughness. Using the percent contact load, the ratio of sliding load to the critical scratch load, the cycles to failure are measured to predict the wear-life of TiN film. On the wear-life diagram the percent loads and the cycle to failure show the good linear relation on semi-log coordinate. With decreasing loads, the diagram shows the wear-limit at which the coated disk survives more than 4000 cycles.

Design Improvement of Carrier Finger on Sheet Metal Forming Line for the Prevention of Scratch (판재 스크래치 저감을 위한 제관 라인 이송 핑거 접촉부의 설계 개선)

  • Lee, Min;Kim, Tae Wan
    • Tribology and Lubricants
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    • v.28 no.5
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    • pp.240-245
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    • 2012
  • In this study, we developed a new carrier finger to prevent scratches in a sheet metal forming line. The developed carrier finger was designed to have a streamlined shape with a larger radius of curvature at the edges, as well as a smaller contact area. To evaluate the scratch alleviation effect, a sliding contact analysis and scratch test using the pin on a plate wear tester were conducted for both the old and new carrier fingers. The results show that, for both transverse and longitudinal movements of the strip, the newly designed carrier finger reduces both the friction and scratch depth by its streamlined shape, which decreases the pressure spike at the edge.