• 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.

• Tribology and Lubricants
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• v.37 no.3
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• pp.83-90
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• 2021

In this study, an ultrasonic nanocrystal surface modification (UNSM) was used to improve the mechanical properties, scratch resistance and tribological performance of Cu-based bimetals, which are usually used to manufacture sliding bearings and bushings for internal combustion engines (ICEs). Two different Cu-based bimetals, namely CuPb10Sn10 and CuSn10Bi7, were sintered onto a low carbon steel substrate. The mechanical properties and dry tribological performance using a tensile tester and micro-tribo tester were evaluated, respectively. The scratch resistance was assessed using a micro-scratch tester at an incremental load. The tensile test results showed that the yield strength (YS) and ultimate tensile strength (UTS) of both Cu-based bimetals increased after UNSM. Furthermore, the scratch and tribological tests results revealed that the scratch resistance and tribological performance of both Cu-based bimetals were improved by the application of UNSM. These improvements were mainly attributed to the eliminated pores, increased hardness and reduced roughness after UNSM. CuSn10Bi7 demonstrated better mechanical properties, scratch resistance and tribological performance than CuPb10Sn10. It was found that the presence of Bi in CuSn10Bi7 formed a Cu₁₁Bi₇ intermetallic phase, which is harder than Cu₃Sn. Hence, CuSn10Bi7 demonstrated higher strength and wear resistance than CuPb10Sn10. In addition, a CuSn10Bi7 formed both SnO₂ and Bi₂O₃ that prevented adhesion and improved the tribological performance. It can be expected that under dry tribological conditions, ICEs can utilize UNSM bearings and bushings made of CuSn10Bi7 instead of CuPb10Sn10 under oil-lubricated conditions.

• Tribology and Lubricants
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• v.39 no.5
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• pp.212-215
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• 2023

Diaphragm compressors play a crucial role in safely compressing large volumes of high-purity hydrogen gas without contamination or leakage, thereby ensuring quality and reliability. Diaphragm compressors use a thin, flat, triple-layered diaphragm plate that is subjected to repetitive piston pressure for compression. They are usually made of metallic materials such as stainless steel or Inconel owing to their high-pressure resistance. However, since they are consumable components, they fail due to fatigue from repetitive pressure and vibration stress. This study aims to evaluate the scratch characteristics of diaphragms in operational environments by conducting tests on three different samples: Inconel 718, AISI 301, and Teflon-coated AISI 301. The Inconel 718 sample underwent a polishing process, the AISI 301 sample used raw material, and the Teflon coating was applied to the AISI 301 substrate at a thickness of 50 ㎛. To assess the scratch resistance, reciprocating motion friction tests were performed using a tribometer, utilizing 220 and 2000 grit sandpapers as the counter materials. The results of the friction tests suggested that the Teflon-coated sample exhibited the lowest initial friction coefficient and consistently maintained the lowest average friction coefficient (0.13 and 0.11 with 220 and 2000 grit, respectively) throughout the test. Moreover, the Teflon-coated diaphragm showed minimal wear patterns, indicating superior scratch resistance than the Inconel 718 and AISI 301 samples. These findings suggest that Teflon coatings may offer an effective solution for enhancing scratch resistance in diaphragms, thereby improving compressor performance in high-pressure hydrogen applications.

• Elastomers and Composites
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• v.43 no.3
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• pp.183-190
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• 2008

In this study, we have investigated mechanical properties and scratch resistance of polypropylene compounds by two types of masterbatch with different molecular weight of PP. Masterbatches were prepared with polypropylene(PP) and polydimethylsiloxane(PDMS) by melt mixing. Mechanical properties and scratch behavior were examined with UTM and polarizing microscope. The morphology surface of grain pattern was investigated Color 3D Laser Scanning Microscope. Mechanical properties of two masterbatches containing PP compounds showed a little bit difference in accordance with amount of M/B. Scratch resistance was much improved by adding masterbatches used high-molecular weight PP. Scratch resistance was excellent when grain pattern of the surface is deep, large, round and irregular.

• Journal of Soil and Groundwater Environment
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• v.6 no.1
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• pp.53-62
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• 2001

Effects of surface defect on thermal stability and stress crack resistance of high density polyethylene geomembranes in environmental conditions were examined by comparing the mechanical properties, chemical resistance and failure times of geomembranes between defective cases under different temperatures. Artificial surface defects were added to the surface of geomembranes by scratch apparatus designed specially. The number of surface defects was increased with the smaller size of scratch induced particles, and the more scratch addition numbers at the shear rate of scratch induced mechanism, 100mm/min. The tensile strength were decreased but the tensile strain was increased with the above conditions. In chemical resistance of defective geomembranes, the tensile strength were decreased but the tensile strain was increased with the longer immersion period and the higher temperature under the same scratch induced conditions. Finally, failure times of defective geomembranes by ESCR test were shifted to the shorter time ranges by increasing temperatures.

• Polymer(Korea)
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• v.33 no.4
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• pp.273-283
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• 2009

Recent research issues on the scratch behaviors of polymeric materials has been investigated. In this study, the scratch characterization of polymeric materials with respect of experimental parameters, such as nature of the material, temperature, applied load, test speed, surface treatment, scratch number of times, polymer structure/functional groups, degree of cross-linking, and crystallinity, are reviewed. In addition, the testing standards and methodologies which could quantify the scratch behaviors are introduced and the current international standards are compared and summarized. The latest technical approaches for evaluating the scratch behaviors and improving the scratch resistance of polymers are also discussed.

• Transactions of Materials Processing
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• v.13 no.1
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• pp.59-64
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• 2004

Nano-scratch tests were performed on PMMA thin films spin-coated on a Si substrate using an atomic force microscopy (AFM) with loads ranging form 10nN to 100nN. At low loads, a ridge pattern was formed on the PMMA thin film surface. No wear particles were observed during the pattern-forming mild wear. At high loads, severe wear by plowing occurred, accompanied by wear particles. The film with the highest hardness showed the highest wear resistance. Friction force generated during the scratching was measured, which was closely related with surface deformation of the film. A simple empirical equation to deduce scratch hardness of the film from a linear fixed-distance scratch test was proposed, and scratching-speed dependency of the scratch hardness was displayed.

• Korean Journal of Materials Research
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• v.26 no.5
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• pp.229-234
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• 2016

In this study, the degree of particle melting in $Y_2O_3$ plasma spraying and its effects on coating characteristics have been investigated in terms of microstructural features, microhardness and scratch resistance. Plasma sprayed $Y_2O_3$ coatings were formed using two different powder feeding systems: a system in which the powder is fed inside the plasma gun and a system in which the powder is fed externally. The internal powder spraying method generated a well-defined lamellae structure that was characterized by a thin porous layer at the splat boundary and microcracks within individual splats. Such micro-defects were generated by the large thermal contraction of splats from fully-molten droplets. The external powder spraying method formed a relatively dense coating with a particulate deposition mode, and the deposition of a higher fraction of partially-melted droplets led to a much reduced number of inter-splat pores and intra-splat microcracks. The microhardness and scratch resistance of the $Y_2O_3$ coatings were improved by external powder spraying; this result was mainly attributed to the reduced number of micro-defects.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.5
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• pp.475-484
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• 2020

Individual curing process of each layer in two resin composites can be caused the separation between two layers. In this study, co-curing process for two resin composites is suggested to improve the inter-layer bonding. Glass fiber reinforced composites with phenolic and epoxy resins were manufactured by co-curing process, and several types of glass/phenolic composites were considered to confirm the application on two resin composites. Experiments for smoke resistance, scratch resistance and flexural strength were carried out to verify requirements corresponding to thermal and mechanical environments. It was validated that two resin composites with phenolic resin impregnated prepreg exhibits good thermal and mechanical characteristics, and it can serve as highly effective composite structures in aerospace and many industry areas.

• Journal of the Korea Furniture Society
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• v.21 no.4
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• pp.284-292
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• 2010

This research was carried out to examine the properties of fancy cherry veneer overlaid on the PF resin bonded Meranti plywood floor, which 2.5% green tea leaf powder was applied in the UV varnishes and the adhesives for scavenging the volatile organic compounds. The results were as follows: 1. The various properties of the treated samples, such as density, moisture content, thickness swelling, bending strength(MOR), adhesion shear strength, surface abrasion, curling, cyclic delamination test with boiling water, boiling property, cold-resistance and heat resistance, acid resistance and alkali resistance, and anti-contamination property showed no significant difference between the properties of the control samples. 2.5% green tea leaf powder treated floor gave a little better results than the control for surface scratch test. 2. In case of QUV and weathering test, no difference between the treated sample and control was found. 3. The floor was discolored by adding 10% green tea leaf powder to UV coating, and the floor was also discolored to light green during by the soaking test. The color of floor was not changed up to 5% addition level.