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Articoli di riviste sul tema "Scratch tests"

Autore: Grafiati

Pubblicato: 29 marzo 2025

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1

Shi, Xin Hong, e Mei Juan Shan. "Effect of Scratch Depths on Fatigue Properties of PMMA for Aircraft Canopies". Applied Mechanics and Materials 687-691 (novembre 2014): 81–84. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.81.

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A series of fatigue tests is performed for polymethyl methacrylate (PMMA) specimens without scratches and with scratches. The scratch depth is set to be 0.2mm, 0.3mm and 0.4mm, respectively. Based on the experimental results, it can be deduced that contained fatigue limit of specimens with scratches significantly decreases compared to specimens without scratches. Besides, contained fatigue limit decreases gradually with scratch depth increasing from 0.0mm to 0.4mm. Consequently, it can be concluded that fatigue properties of PMMA will decrease when there exists scratch and for scratch depth from 0.0mm to 0.4mm, fatigue property decreases remarkably with deeper scratch.

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Shi, Xin Hong, e Mei Juan Shan. "Effect of Scratch Depths on Tensile Strength of PMMA for Aircraft Canopies". Advanced Materials Research 1056 (ottobre 2014): 8–11. http://dx.doi.org/10.4028/www.scientific.net/amr.1056.8.

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Static tensile tests of polymethyl methacrylate (PMMA) specimens without scratches and containing a scratch whose depth was set to be 0.2mm, 0.3mm and 0.4mm, respectively, were carried out to explore effect of scratch depths on tensile strength of PMMA. Based on the experimental load-displacement curves, the specimens without scratches deform most severely when the failure comes forth. The failure deformation declines gradually with higher scratch depth, namely higher scratch depth leads to lower plastic deformation. It thus follows that the scratch significantly reduces the tensile strength of PMMA while the variation of the scratch depth from 0.2mm to 0.4mm has negligible influence on the tensile strength of PMMA.

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3

Zhao, Xu, Yadong Gong, Ming Cai e Bing Han. "Numerical and Experimental Analysis of Material Removal and Surface Defect Mechanism in Scratch Tests of High Volume Fraction SiCp/Al Composites". Materials 13, n. 3 (10 febbraio 2020): 796. http://dx.doi.org/10.3390/ma13030796.

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This paper addresses a comprehensive and further insight into the sensitivity of material removal and the surface defect formation mechanism to scratch depth during single-grit scratch tests of 50 vol% SiCp/Al composites. The three-dimensional (3D) finite element model with more realistic 3D micro-structure, particle-matrix interfacial behaviors, particle-particle contact behaviors, particle-matrix contact behaviors and a Johnson-Holmquist-Beissel (JHB) model of SiC was developed. The scratch simulation conducted at scratch velocity 10 mm/min and loading rate 40 N/min revealed that the scratch depth plays a crucial role in material removal and the surface forming process. Brittle fracturing of SiC particles and surface defects become more deteriorative under a large scratch depth ranging from 0.0385 to 0.0764 μm. The above phenomenon can be attributed to the influence of scratch depth on SiC particles’ transport; the increase in the amount of SiC particle transport resulting from an increase of scratch depth raises the occurrence of particle-particle collision which provides hard support and shock for the scratched particles; therefore, brittle fracturing gradually becomes the major removal mode of SiC particles as the scratch depth increases. On the deteriorative surface, various defects are observed; i.e., lateral cracks, interfacial debonding, cavies filled with residually broken particles, etc. The von Mises stress distribution shows that SiC particles bear vast majority of load, and thus present greater stress than the surrounding Al matrix. For example: their ratio of 3 to 30 under the scratch depth of 0.011 mm. Namely, SiC particles impede stress diffusion within the Al matrix. Finally, the SEM images of the scratched surface obtained from the single-grit scratch experiments verify the numerical analysis’s results.

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4

Duan, Miaomiao, Zhufeng Yue e Qianguang Song. "Effect of Superficial Scratch Damage on Tension Properties of Carbon/Epoxy Plain Weave Laminates". Advances in Civil Engineering 2021 (31 marzo 2021): 1–8. http://dx.doi.org/10.1155/2021/5590448.

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The effect of scratch damage on the tension properties of carbon fiber plain weave laminates has been studied in detail using digital image correlation (DIC) and acoustic emission (AE). A range of scratch lengths was machined onto different laminates. The bearing capacity of the laminates was then compared with that of unaltered samples. The strain field distributions near the scratches were measured and analyzed as a function of scratch length with DIC. Initiation and propagation of damage were monitored during the tensile tests using AE. Failure sites and morphologies were observed and analyzed. The results show that superficial scratches have little effect on the strength of plain weave laminates when the scratch length is less than 80% of the specimen width. Scratches affect the distribution of strain near the scratch but not far away from the scratch or at the back face of the sample. Not all samples broke from the scratch site but instead broke from the free edge of the sample or close to the gripping region.

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5

da Silva, Dayanne Lopes, Emanuel Santos, Sérgio de Souza Camargo e Antônio Carlos de Oliveira Ruellas. "Infrared spectroscopy, nano-mechanical properties, and scratch resistance of esthetic orthodontic coated archwires". Angle Orthodontist 85, n. 5 (24 novembre 2014): 777–83. http://dx.doi.org/10.2319/070314-472.1.

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ABSTRACT Objective: To evaluate the material composition, mechanical properties (hardness and elastic modulus), and scratch resistance of the coating of four commercialized esthetic orthodontic archwires. Materials and Methods: The coating composition of esthetic archwires was assessed by Fourier-transform infrared spectroscopy (FTIR). Coating hardness and elastic modulus were analyzed with instrumented nano-indentation tests. Scratch resistance of coatings was evaluated by scratch test. Coating micromorphologic characteristics after scratch tests were observed in a scanning electron microscope. Statistical differences were investigated using analysis of variance and Tukey post hoc test. Results: The FTIR results indicate that all analyzed coatings were markedly characterized by the benzene peak at about 1500 cm−1. The coating hardness and elastic modulus average values ranged from 0.17 to 0.23 GPa and from 5.0 to 7.6 GPa, respectively. Scratch test showed a high coating elasticity after load removal with elastic recoveries >60%, but different failure features could be observed along the scratches. Conclusion: The coatings of esthetic archwires evaluated are probably a composite of polyester and polytetrafluoroethylene. Delamination, crack propagation, and debris generation could be observed along the coating scratches and could influence its durability in the oral environment.

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6

Zhang, Xianlei, Kefan Jiao, Shaoshuai Ma e Yunyun Wu. "Effect of Scratches on Mechanical Properties and Impermeability of PVC-P Geomembranes". Polymers 17, n. 3 (22 gennaio 2025): 277. https://doi.org/10.3390/polym17030277.

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Plasticized polyvinyl chloride (PVC-P) geomembranes (GMBs) are susceptible to physical scratches due to improper construction in water conservancy projects. Axial tensile tests and permeability tests were carried out to investigate the mechanical properties and impermeability of PVC-P GMBs with scratches under various combinations of scratch angles, lengths, and depths. This was achieved by evaluating the break strength, break elongation, Young’s modulus, and permeability coefficient. The results demonstrated that physical scratches weaken the mechanical properties of PVC-P GMBs, and interactions among the influencing factors were observed. The influence of scratches on the break elongation and break strength outweighed that on Young’s modulus, with scratch depth exerting the most significant effect on the mechanical properties under identical conditions. The scratches on PVC-P GMBs should be minimized in practice, while those without penetrating cracks along the thickness direction and tensile deformation have negligible effects on impermeability. The failure threshold of PVC-P GMBs with scratches was determined, along with the scratch depths, angles, and lengths affecting the operation of the project. This provides a reference for assessing whether PVC-P GMBs with scratches jeopardize the safety of projects.

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7

Leung, H. M., e Sujeet K. Sinha. "Scratch and indentation tests on seashells". Tribology International 42, n. 1 (gennaio 2009): 40–49. http://dx.doi.org/10.1016/j.triboint.2008.05.015.

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8

Lin, Jeen-Shang, e Yaneng Zhou. "Can scratch tests give fracture toughness?" Engineering Fracture Mechanics 109 (settembre 2013): 161–68. http://dx.doi.org/10.1016/j.engfracmech.2013.06.002.

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9

Richard, Thomas, Fabrice Dagrain, Edmond Poyol e Emmanuel Detournay. "Rock strength determination from scratch tests". Engineering Geology 147-148 (ottobre 2012): 91–100. http://dx.doi.org/10.1016/j.enggeo.2012.07.011.

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10

Patzelt, B., e U. Hemmann. "Scratch-Tests zur Untersuchung der Abrasionsbeständigkeit". Materialwissenschaft und Werkstofftechnik 28, n. 10 (ottobre 1997): 500–504. http://dx.doi.org/10.1002/mawe.19970281013.

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11

Tharajak, Jirasak, Tippaban Palathai e Narongrit Sombatsompop. "Scratch Resistance and Adhesion Properties of PEEK Coating Filled with h-BN Nanoparticles". Advanced Materials Research 747 (agosto 2013): 303–6. http://dx.doi.org/10.4028/www.scientific.net/amr.747.303.

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Effects of h-BN particles on mechanical properties and adhesion of semi-crystalline poly (ether-ether-ketone) (PEEK) coatings were studied. PEEK powder was mixed with various contents of h-BN nanoparticle in ethanol under ultrasonic mixing. As-mixed powders were sprayed onto low carbon steel substrate with thermal spray technique. The hardness, scratch hardness, specific scratch wear rate, prevailing deformation mechanisms and adhesion were obtained from scratch tests by varying the applied load. The damage geometry on scratched polymer surfaces and scratch wear volume loss were examined using scanning electron microscope (SEM) and surface profilometer, respectively. The results indicated that the addition of h-BN content improved the hardness of the composite. In addition, the specific scratch wear rate and the adhesion between PEEK coatings and substrate decreased with increasing h-BN content. The poor adhesion resulted from the reductions of flow-ability and viscosity between PEEK and substrate caused by heat dissipation from the h-BN particles.

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12

Niinimäki, A. "Scratch-chamber tests in food handler dermatitis". Contact Dermatitis 16, n. 1 (gennaio 1987): 11–20. http://dx.doi.org/10.1111/j.1600-0536.1987.tb02609.x.

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13

Chen, Junhai, Y. Feng, Yijin Zeng, Yannong Han, Yi Wang e Chengcheng Niu. "Continuous rock drillability measurements using scratch tests". Journal of Petroleum Science and Engineering 159 (novembre 2017): 783–90. http://dx.doi.org/10.1016/j.petrol.2017.08.030.

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14

el Saved, F., e J. Bazex. "Scratch-chamber tests in meat handler's dermatitis". Contact Dermatitis 30, n. 4 (aprile 1994): 256. http://dx.doi.org/10.1111/j.1600-0536.1994.tb00666.x.

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15

Pistor, Christoph, e Klaus Friedrich. "Scratch and indentation tests on polyoxymethylene (POM)". Journal of Applied Polymer Science 66, n. 10 (5 dicembre 1997): 1985–96. http://dx.doi.org/10.1002/(sici)1097-4628(19971205)66:10<1985::aid-app15>3.0.co;2-u.

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16

Barletta, M., A. Gisario, G. Rubino e L. Lusvarghi. "Influence of scratch load and speed in scratch tests of bilayer powder coatings". Progress in Organic Coatings 64, n. 2-3 (febbraio 2009): 247–58. http://dx.doi.org/10.1016/j.porgcoat.2008.09.007.

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17

Wu, T. W. "Microscratch and load relaxation tests for ultra-thin films". Journal of Materials Research 6, n. 2 (febbraio 1991): 407–26. http://dx.doi.org/10.1557/jmr.1991.0407.

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The microindenter has proven to be a powerful device in the characterization of the mechanical properties of thin films. The machine has both high resolution in the applied load and penetration depth measurements, as well as the versatility to perform different types of testing. The former provides the capability to deal with extremely thin films, while the latter allows for other mechanical properties, in addition to hardness, to be acquired. Four types of tests, namely indentation, scratch, load relaxation, and indentation fatigue tests can currently be conducted using the microindenter via different operating procedures. Only the scratch and load relaxation techniques will be covered in this paper. In a microscratch test, the normal load, tangential load, scratch length, and acoustic emission are monitored simultaneously during an entire scratch process for the purposes of measuring the critical load and studying the failure mechanisms of the deposited films. The adhesion strength, scratch hardness, fracture toughness, and friction are the mechanical properties which are possible to obtain by using this technique. Results from aluminum, carbon, and zirconia coatings will be discussed. The load relaxation test provides information on the creep properties of the films and results in an empirical constitutive relation between the applied stress and plastic strain rate. The creep properties of DC sputtered Al films will be used as an illustration of this.

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18

Feng, Biao. "Effects of surface roughness on scratch resistance and stress-strain fields during scratch tests". AIP Advances 7, n. 3 (marzo 2017): 035217. http://dx.doi.org/10.1063/1.4979332.

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19

Devenport, Timothy, Bernard Rolfe, Michael Pereira e James M. Griffin. "Analysis of Acoustic Emissions for Determination of the Mechanical Effects of Scratch Tests". Applied Sciences 12, n. 13 (2 luglio 2022): 6724. http://dx.doi.org/10.3390/app12136724.

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Acoustic Emission (AE) is a promising technique for measuring tool wear online and in real time. In this work, scratch tests were conducted to better understand the “pre-wear” AE response based on loading conditions that were not sufficient to generate galling. The scratch tests used the same type of indenter against two different sheet materials: aluminum and steel. The results showed that AE parameters such as the mean frequency, Centroid frequency and Shannon entropy outperformed other frequency domain techniques by discriminating between the two sheet materials in scratch tests. From the literature, the frequency region of interest was expected to be sub 300 kHz. However, in this study, activity below this threshold was found to be noise, whereas distinct frequencies were found at much higher frequencies than expected. These results are compared against single grit “SG” tests of both mild steel- and nickel-based superalloys to allow comparison of the two test methods and materials used. This comparison showed that the SG tests excited the acoustic emission in ways in which the scratch tests did not. Another factor when using acoustic emissions to monitor sheet metal forming is the differences obtained in energy–frequency mapping, where many report the galling phenomena between a certain amplitude and frequency range. Such results are specific to the setup and the materials/geometries used. Further work presented here compares different scratch tests where energy–frequency mapping is different for different materials/geometries.

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Meneses-Amador, A., L. F. Jiménez-Tinoco, C. D. Reséndiz-Calderon, A. Mouftiez, G. A. Rodríguez-Castro e I. Campos-Silva. "Numerical evaluation of scratch tests on boride layers". Surface and Coatings Technology 284 (dicembre 2015): 182–91. http://dx.doi.org/10.1016/j.surfcoat.2015.06.088.

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21

Kataruka, Amrita, Kavya Mendu, Orieka Okeoghene, Jasmine Puthuvelil e Ange-Therese Akono. "Microscopic assessment of bone toughness using scratch tests". Bone Reports 6 (giugno 2017): 17–25. http://dx.doi.org/10.1016/j.bonr.2016.12.001.

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22

LEE, SEONG-MIN. "EFFECT OF GRINDING-INDUCED SCRATCH GEOMETRY ON FRACTURE STRENGTH OF PLASTIC-ENCAPSULATED SEMICONDUCTOR DEVICES". Surface Review and Letters 17, n. 03 (giugno 2010): 323–27. http://dx.doi.org/10.1142/s0218625x10013916.

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The fracture strength of LOC (lead-on-chip) packages was measured through three-point bending tests. Metallurgical examination shows that failure in an LOC package begins at a pre-existing flaw in the form of a scratch on the bottom surface of the plastic-encapsulated silicon chip. The flexural strength of LOC packages was estimated as a function of the geometry of the grinding-induced scratches on the back surface of the chips. The major conclusion is that the fracture strength of the plastic package, including the silicon chip, can be enhanced up to 80% by changing its scratch marks from 0°, running parallel to its lateral direction, to 90°, running parallel to its longitudinal direction.

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23

Menezes, Pradeep L., Kishore e Satish V. Kailas. "Effect of Roughness Parameter and Grinding Angle on Coefficient of Friction When Sliding of Al–Mg Alloy Over EN8 Steel". Journal of Tribology 128, n. 4 (29 aprile 2006): 697–704. http://dx.doi.org/10.1115/1.2345401.

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Surface topography of harder mating surface plays an important role in metal forming operations as it predominantly controls the frictional behavior at the interface. In the present investigation, an inclined scratch tester was used to understand the effect of direction of surface grinding marks on interface friction and transfer layer formation. EN8 steel flats were ground to attain different surface roughnesses with unidirectional grinding marks. Al–Mg alloy pins were then scratched against the prepared EN8 steel flats. The grinding angle (angle between direction of scratch and grinding marks) was varied between 0 deg and 90 deg during the scratch tests. Scanning electron micrography of the contact surfaces revealed the transfer layer morphology. The coefficient of friction and transfer layer formation were observed to depend primarily on the direction of grinding marks of the harder mating surface, and independent of the surface roughness of harder mating surface. The grinding angle effect was attributed to the variation of plowing component of friction with grinding angle.

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Čtvrtlík, Radim, Lukáš Václavek e Jan Tomáštík. "WHY MONITOR ACOUSTIC EMISSIONS DURING NANOMECHANICAL TESTS?" Acta Polytechnica CTU Proceedings 27 (11 giugno 2020): 126–30. http://dx.doi.org/10.14311/app.2020.27.0126.

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Acoustic Emissions (AE) monitoring has been proved as an effective non-destructive technique at the macro scale. Nevertheless, it may also be employed at nano/micro scale during nanomechanical and nanotribological testing. Local mechanical properties of surfaces or micro object are routinely explored using nanoindentation, scratch test or dynamic impact tests that are evaluated based on analysis of depth-load-time records or microscopic observation of residual indents, scratch grooves or impact craters, respectively. Although these approaches have been proven to be sufficient in most cases for a variety of materials, there are many situations where they do not provide sufficient information for a complex understanding of the deformation response. On the other hand, analysis of AE signals generated during these tests may provide valuable complementary information and provide some insight into the dynamics of phenomena like cracking, phase transitions, plastic instabilities, etc. That means that the analysis of acoustic emissions provides a better understanding and more complex interpretation of the results obtained by the above-mentioned tests. The strength of the AE based method is demonstrated for optical thin films deposited on glass tested via scratch test. Combination of AE and nanoindentation will be presented for various types of glasses. The complementary analysis of the time and frequency domain will draw the potential of the AE extended approach. Especially dynamics of the failure and fracture processes will be distinguished and elucidated. In both cases the analysis of AE events will be correlated with standard approaches.

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Opavsky, Mary Anne. "Cat Scratch Disease: The Story Continues". Canadian Journal of Infectious Diseases 8, n. 1 (1997): 43–49. http://dx.doi.org/10.1155/1997/982908.

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OBJECTIVE: To present a perspective on the current state of knowledge of cat scratch disease (CSD), including the evidence forBartonella henselaeas the etiological agent, epidemiological and clinical characteristics of the disease, available diagnostic tests and current therapeutic options.DATA SOURCES: MEDLINE search of the literature published from 1966 to 1995 using ‘cat scratch disease’, ‘Bartonella henselae’, ‘Rochalimaea henselae’ as key words and bibliographies of selected papers.DATA EXTRACTION: Selected studies reporting data on etiology, epidemiology, clinical characteristics, diagnosis and therapy of CSD were evaluated.DATA SYNTHESIS AND CONCLUSIONS: Evidence accumulated to date supportsB henselaeas the etiological agent of CSD. The most significant risk factors for CSD are being licked on the face, scratched or bitten by a kitten and owning a kitten with fleas. Available serological tests can confirm classic CSD and identifyB henselaeas the cause of more atypical presentations, such as fever of unknown origin, granulomatous hepatitis, encephalitis and osteomyelitis. Symptomatic management is appropriate for isolated lymphadenopathy caused by CSD in healthy individuals; however, antibiotic therapy may be indicated for patients with more severe manifestations of the disease and immunocompromised hosts. Further study of CSD, in particular the epidemiology and therapy, is warranted. A better understanding of the pathogenesis ofB henselaeinfection will have important implications in both immunocompetent and immunocompromised individuals.

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Jones, V. C., I. R. Williams, D. D. Auger, W. Walsh, D. C. Barton, M. H. Stone e J. Fisher. "Quantification of third body damage to the tibial counterface in mobile bearing knees". Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 215, n. 2 (1 febbraio 2001): 171–79. http://dx.doi.org/10.1243/0954411011533733.

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Fourteen pairs of explanted low contact stress (LCS) tibial interface components: six rotating platform (RP), six meniscal (MN) and two anterior-posterior (AP) glide designs, have been analysed with particular attention paid to the condition of the tibial counterfaces. The average surface roughness, Ra, for the tibial trays ranged from 0.01 to 0.087 μm, significantly greater than the unworn control measurement of 0.008 μm. The scratch geometry analysis showed that the scratch peaks were found to be consistently of a lower aspect ratio than the scratch valleys and under 1 μm in height (average asperity height - Rp = 0.52 μm, aspect ratio Δ p = 0.01, average asperity depth Rv = 1.10 μm, Δ v = 0.05). The largest scratches were 3-4 μm in both Rp and Rv In vitro tests have shown that ultra-high molecular weight polyethylene (UHMWPE) wear increases in the presence of counterface scratches perpendicular to the direction of motion. In these explants, the unidirectional motion produced scratches parallel to the direction of sliding which is predicted to produce a smaller increase in UHMWPE wear. Other designs in mobile bearing knees have less constrained motion at the tibial counterface and this has been shown to accelerate wear; it may also lead to a further increase in wear in the presence of third body scratches. It may be possible in future knee designs to reduce this type of wear damage by introducing alternative materials or coatings which are more resistant to scratching and surface roughening.

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Lafaye, S., C. Gauthier e R. Schirrer. "Analyzing friction and scratch tests without in situ observation". Wear 265, n. 5-6 (agosto 2008): 664–73. http://dx.doi.org/10.1016/j.wear.2007.12.005.

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Hubler, Mija H., e Franz-Josef Ulm. "Size-Effect Law for Scratch Tests of Axisymmetric Shape". Journal of Engineering Mechanics 142, n. 12 (dicembre 2016): 04016094. http://dx.doi.org/10.1061/(asce)em.1943-7889.0001159.

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Akono, Ange-Therese, e Franz-Josef Ulm. "Fracture scaling relations for scratch tests of axisymmetric shape". Journal of the Mechanics and Physics of Solids 60, n. 3 (marzo 2012): 379–90. http://dx.doi.org/10.1016/j.jmps.2011.12.009.

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Akbari, Mansur, Mikhail Kliuev, Jens Boos e Konrad Wegener. "Temperature and force measurements in single diamond scratch tests". International Journal of Advanced Manufacturing Technology 96, n. 9-12 (25 marzo 2018): 4393–405. http://dx.doi.org/10.1007/s00170-018-1930-0.

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Feng, Biao. "Tribology behavior on scratch tests: Effects of yield strength". Friction 5, n. 1 (marzo 2017): 108–14. http://dx.doi.org/10.1007/s40544-017-0148-8.

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TOMITA, Kazuhiro, Naotaka YOSHIKAWA, Miwako TODA, Tomoko HIRAYAMA, Takashi MATSUOKA e Hidetoshi SOMEKAWA. "316 Microstructual evolution during nano-scratch tests in Mg". Proceedings of Conference of Kansai Branch 2014.89 (2014): _3–25_. http://dx.doi.org/10.1299/jsmekansai.2014.89._3-25_.

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Lee, Kwangmin, Karuppasamy Pandian Marimuthu, Chang-Lae Kim e Hyungyil Lee. "Scratch-tip-size effect and change of friction coefficient in nano / micro scratch tests using XFEM". Tribology International 120 (aprile 2018): 398–410. http://dx.doi.org/10.1016/j.triboint.2018.01.003.

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Santos, E., S. S. Camargo, G. A. Soares e Neide K. Kuromoto. "Tribological Characterization of Porous TiO₂ Coatings Produced by Electrodeposition". Key Engineering Materials 493-494 (ottobre 2011): 430–35. http://dx.doi.org/10.4028/www.scientific.net/kem.493-494.430.

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In this work, the resistance to scratch and wear (pin-on-flat) tests of five different porous TiO2 films were compared. Such tribological tests were carried out under dry conditions. The coatings were electrodeposited on commercially pure-Ti by anodic oxidation method in different electrolyte solutions at constant voltages. The scratch tests were conducted by applying increasing normal loads up to 400 mN. The coefficient of friction (COF) varied from 0.2 up to 0.5, and increased at larger penetrations depths. When the electrolyte concentration was changed from 0.5 into 1.0M H2SO4, the COF slightly decreased. Scanning electron microscopy indicated that the coatings produced in H2SO4/150V and Na2SO4/100V did not have their substrates revealed. In addition, the samples anodized in H2SO4/150V had the highest elastic recoveries. Therefore, such coatings seem to be more resistant to scratch tests than the others. The wear tests were carried out with Berkovich tip as counter-face under constant normal loads of 10 mN in 10 forward-backward cycles. The coatings deposited in H2SO4/150V had the lowest wear volume rates. The findings suggest that the porous Ti oxide coatings electrodeposited above their rupture voltages are more suitable to both scratch- and wear-resistance compared to those prepared at the lowest voltage (H2SO4/100V).

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Gu, W., Z. Yao e K. Li. "Evaluation of subsurface crack depth during scratch test for optical glass BK7". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, n. 12 (30 giugno 2011): 2767–74. http://dx.doi.org/10.1177/0954406211412458.

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To get insight into the deformation and fracture behavior of brittle materials during abrasive process, scratch tests with linearly increasing normal load and constant normal load were conducted on BK7 using Vickers indenters. The effect of the applied normal load on the characteristics of surface cracks as well as the square of the scratch depth was found insensitive to the two load conditions discussed here. By taking both scratch and residual depths into consideration, a model of scratch hardness for brittle material was developed. Based on this scratch hardness, the correlation between the depth of the subsurface cracks and the scratch depth was established and was found in general agreement with the experimental results.

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Sugiyama, Naohiro, Takeshi Mitani, Isaho Kamata, Tomohisa Kato, Hidekazu Tsuchida e Hajime Okumura. "Formation of Double Shockley Stacking Faults in Heavily Nitrogen Doped 4H-SiC Crystal with Reduction of Residual Stress around Scratch Damage". Materials Science Forum 1004 (luglio 2020): 427–32. http://dx.doi.org/10.4028/www.scientific.net/msf.1004.427.

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The scratch damage that caused the generation of double Shockley stacking faults (DSFs) in heavily nitrogen doped 4H-SiC crystal was investigated quantitatively. Scratch tests were carried out on 4H-SiC substrates with a nitrogen concentration of 2.6 × 1019 cm-3. A residual tensile stress of 40 MPa was detected around the scratch loaded at 30 mN with a diamond tip. DSFs were generated from this scratch by annealing at 1100°C for 2 h in Ar atmosphere. After annealing, the residual stress around the scratch was reduced to a tensile stress of 10 MPa. This result suggests that the reduction of residual stress around the scratch coincided with the formation of DSFs.

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37

Sharke, Paul. "Gears from Scratch". Mechanical Engineering 123, n. 12 (1 dicembre 2001): 40–43. http://dx.doi.org/10.1115/1.2001-dec-1.

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This article discusses plastic gears that are ideally suited to the power transmission demands of a rotary sprinkler. They operate in wet conditions without oil or grease. Despite many advances in plastic gear technology, users of metal gears have not begun trading in all their current cogs for plastic versions. In order to reduce the chance of plastic gears jumping teeth in its sprinkler head, Hunter Irrigation molded an asymmetric tooth on the pinion that drives the ring. According to an expert, mold enough of them and plastic gears eventually compete with, then surpass, the economics of metal gears. Closter, New Jersey-based Intech Corp. has developed a method of cutting gears from plastic to take advantage of the material’s strengths. LNP Engineering Plastics Inc. of Exton, Pennsylvania, makes pellets for manufacturers of plastic parts. Ed Williams, an LNP application development engineer and chairman of the AGMA Plastic Gearing Committee, said that despite limited engineering data for plastic gears, designers can find other ways to determine how well certain materials will suit an application. Compiled wear data exists for plastic based on thrust washer wear tests, for instance.

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38

Alamgir, Asad, Maxim Yashin, Andrei Bogatov, Mart Viljus, Rainer Traksmaa, Jozef Sondor, Andreas Lümkemann, Fjodor Sergejev e Vitali Podgursky. "High-Temperature Tribological Performance of Hard Multilayer TiN-AlTiN/nACo-CrN/AlCrN-AlCrO-AlTiCrN Coating Deposited on WC-Co Substrate". Coatings 10, n. 9 (22 settembre 2020): 909. http://dx.doi.org/10.3390/coatings10090909.

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Mechanical and tribological properties of the hard-multilayer TiN-AlTiN/nACo-CrN/AlCrN-AlCrO-AlTiCrN coating deposited on WC-Co substrate were investigated. The sliding tests were carried out using ball-on-disc tribometer at room (25 °C) and high temperatures (600 and 800 °C) with Al2O3 balls as counterpart. Nano-scratch tests were performed at room temperature with a sphero-conical diamond indenter. The surface morphology and chemical composition were investigated with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and in-situ high-temperature X-ray diffraction (HT-XRD). The phase transition from fcc-(Al,Cr)2O3 into α-(Al,Cr)2O3 was observed at about 800 °C. The results of the tribological tests depends on the temperature, the lowest apparent and real wear volumes were observed on the coating after the test at 800 °C along with the smallest coefficient of friction (COF). The plastic deformation of the coating was confirmed in sliding and nano-scratch tests. The nano-scratch tests revealed the dependence of COF value on the temperature of the sliding tests.

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39

Buršíková, Vilma, Jiří Buršík, Lukáš Zábranský, Pavel Souček e Petr Vašina. "Study of the Local Mechanical Properties of Magnetron Sputtered Nanolaminate Coatings". Defect and Diffusion Forum 368 (luglio 2016): 111–14. http://dx.doi.org/10.4028/www.scientific.net/ddf.368.111.

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Nanostructure coatings based on boroncarbide were prepared using magnetron sputtering technique. The mechanical properties of the coatings were tested using quasi-static and dynamic nanoindentation tests with Berkovich and cube-corner indenters. The fracture resistance of the coatings and the coating/substrate interface was studied. Moreover, the dynamic wear and scratch resistance of the coatings was evaluated by means of impact and scratch tests.

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40

Lofaj, Frantisek, e Dušan Németh. "FEM of Cracking during Nanoindentation and Scratch Testing in the Hard W-C Coating/Steel Substrate System". Key Engineering Materials 784 (ottobre 2018): 127–34. http://dx.doi.org/10.4028/www.scientific.net/kem.784.127.

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Finite element modelling (FEM) and eXtended FEM (XFEM) combined with the experimental nanoindentation and scratch tests have been used to simulate the process of cohesive cracking in W-C coating on softer and more ductile steel substrate during nanoindentation and scratch testing. The formation of single and multiple circular “frame” cohesive cracks in the sink-in zone during nanoindentation were explained by the development of high local tensile stresses in the coatings controlled by the plastic deformation of the substrate. Analogous mechanisms were successfully applied to the simulation of multiple Chevron type cracking during scratch testing. Thus, the ability of XFEM to predict the formation of different types of cohesive cracks was confirmed. It was also demonstrated that both nanoindentation and scratch tests in combination with XFEM can be used as the methods to determine the strength and fracture toughness of thin coatings.

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41

Kataria, Satender, Niranjan Kumar, Sitaram Dash e Ashok Kumar Tyagi. "Deformation of SS 304 LN during Scratch Test and Influence on Evolution of Coefficient of Friction". Advances in Tribology 2009 (2009): 1–4. http://dx.doi.org/10.1155/2009/648075.

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An AISI 304 LN nuclear grade forged, metallographically polished specimen was subjected to progressive load scratch tests using a spheroconical indenter at three different scratch speeds 1, 3, and 27 mm/min. The present study attempts to address the evolution of coefficient of friction with scratch speed invoking its correlation with scratch induced deformation in the specimen. At higher scratch speeds, plastic deformation rates were higher which caused friction coefficient to be of higher magnitude. This was correlated with dynamically obtained high resolution optical images that revealed deformation driven microstructural alterations. These alterations significantly influenced the evolution of friction coefficient which was intimately related to plasticity of the surface.

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42

OTTO, Mateusz, Sławomir ZIMOWSKI, Wojciech SIKORA e Tomasz MOSKALEWICZ. "MECHANICAL AND TRIBOLOGICAL ANALYSIS OF MONOLITH AND COATING POLYETHERETHERKETONE". Tribologia 286, n. 4 (31 agosto 2019): 73–86. http://dx.doi.org/10.5604/01.3001.0013.5967.

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In this work, a comparative analysis of the micromechanical and tribological properties of polyetheretherketone (PEEK) in bulk and coating form was performed. The PEEK 708 coating was applied on a Ti6Al4V titanium alloy flat specimen using the electrophoretic deposition method. The micromechanical properties were determined through indentation tests performed using the Vickers method and scratch tests. Based on research work, the Vickers hardness (HV), elastic modulus (E), scratch hardness (HS), and Micro Mar Resistance (MMR) were determined. The tribological properties were defined by the coefficient of friction (fs and fw), which was obtained in scratch tests and ball-on-disk tests. The results of this research indicate, despite the slightly higher Vickers hardness (HV) of the PEEK 708 coating (HV=350 MPa, HS=300 MPa) relative to PEEK bulk (HV=300 MPa, HS=210 MPa), that there is an almost 40% difference between the scratch hardness (HS) values of these PEEK forms. It appears from the result analysis in this paper that testing methods to determine the micromechanical and tribological properties of PEEK in monolith form can be used for both PEEK coatings. Under certain test conditions, the impact of the substrate properties on the results of the PEEK 708 coating was not found.

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43

Jiang, Feng, L. Yan, Y. M. Rong e Y. P. Liu. "Mechanical Modeling of Plowing Process and Experimental Validation". Key Engineering Materials 499 (gennaio 2012): 241–46. http://dx.doi.org/10.4028/www.scientific.net/kem.499.241.

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In this study, mechanical model of plowing process considering material flow process was built. Dynamic material model of workpiece (AISI D2) was included in this plowing model. The friction between diamond indenter against AISI D2 steel was obtained by the ball-on-plate test. The scratch tests with diamond indenter against AISI D2 steel were performed. The scratch morphology was investigated by white light interferometer. The scratch forces in the different loads were calculated by the mechanical model of plowing process. The calculated scratch forces showed good agreement with experimental results.

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44

Zhang, Man Chao, e Zhen Qiang Yao. "The Force in Single-Pass Scratch Tests at Variable Sliding Velocities". Applied Mechanics and Materials 281 (gennaio 2013): 465–68. http://dx.doi.org/10.4028/www.scientific.net/amm.281.465.

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To investigate the characteristics of material removal mechanism in the continuous contour control grinding. It is simplified as a variable speed single grit scratching the surface of quench hardening AISI 5140 steel. Utilizing optical microscope, optical proﬁling system and displacement transducers, the scratch morphology and force were analyzed with applied normal load (depth) and scratch separation distance. Piles-up at the sides of the groove is no obvious change with traverse speed pulse. Both the normal force and the tangential force increase with an increase in traverse speed and depth. The change of traverse speed leads to force fluctuating, and then the forces fall down rapidly to a constant value relatively.

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45

Gallego, Antolino, Jose F. Gil, J. M. Vico, Enrique Díaz Barriga-Castro, J. E. Ruzzante e Rosa Piotrkowski. "Wavelet Transform and Bispectrum Applied to Acoustic Emission Signals from Adherence Scratch-Tests on Corroded Galvanized Coatings". Advanced Materials Research 13-14 (febbraio 2006): 83–88. http://dx.doi.org/10.4028/www.scientific.net/amr.13-14.83.

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Wavelet analysis and bispectrum was applied to Acoustic Emission (AE) signals from scratch tests on corroded hot-dip galvanized samples in order to achieve the detection of corrosion products in pieces non reachable by visual inspection. AE signals were correlated with the fracture mechanisms occurring during scratch tests, while the contact force increased. Results were corroborated by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and X-Ray Diffraction (XRD).

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46

Ding, Hua, Yu Ting He, Jin Qiang Du, Li Ming Wu, Hai Wei Zhang e Qing Shao. "Local Stress-Strain Method for the Effects of Scratch on Fatigue Performances of Cabin Glass". Advanced Materials Research 299-300 (luglio 2011): 51–56. http://dx.doi.org/10.4028/www.scientific.net/amr.299-300.51.

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The three-dimensional finite element model of cabin glass with surface scratch is built using the finite element software ANSYS, which is aimed to analyze the detailed stress around the scratch route tip. Then the fatigue notch factor can be gained through utilizing of results from three-dimensional model, which is followed by the estimation of fatigue life based on local stress-strain method. It is found that the stress around scratch route tip is nearly linearly increased with the increasing of tip depth (0.2mm<h<0.8mm) and the fatigue performances of cabin glass with surface scratch are sensitive to scratch depth. Finally, fatigue tests are carried out with the specimens of different scratch route tip depths, and validation against fatigue life by local stress-strain method and experimental data shows a good agreement, which indicates that the scratch model and the local stress-strain method for the effects of scratch on cabin glass fatigue performances are valid.

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47

Kansteiner, Michael, Monika Kipp, Swetlana Herbrandt, Manuel Ferreira e Dirk Biermann. "Process Forces and Groove Development in Single Grain Scratch Tests of Concrete and Reinforced Concrete". Applied Mechanics and Materials 794 (ottobre 2015): 207–14. http://dx.doi.org/10.4028/www.scientific.net/amm.794.207.

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Diamond impregnated tools are commonly used for the machining of concrete and rocks, e.g. sawblades or core drills. These tools consist of a metal bond and randomly distributed diamonds. The grinding of inhomogeneous materials like concrete is a complex system which is interfered by a large number of influencing factors. Although simple models exist describing the material removal processes, there is still a lack of knowledge concerning the fundamental mechanisms during grinding. Thus, the optimisation and development of diamond tools are mainly based on experience and empirical methods. Concrete is described as a compound material which exhibits different phases of minerals like cement and aggregate phases. In reinforced concrete, steel is a further phase which has got highly different properties in comparison to the mineral phases. The detailed analysis of the material removal mechanisms is difficult because of the random phase composition of concrete and the random diamond distribution within the tools as well. But, the knowledge of the material removal mechanisms are of vital interest for the development of efficient tools. A fundamental understanding of material removal processes and wear mechanisms can be drawn from single grain scratch tests. Recent developments in diamond tool manufacturing provide the defined positioning of diamond grains in the tool body. This offers new possibilities based on scratch tests regarding tool development. Thus, scratch tests on concrete and reinforced concrete were conducted using single grain diamond tools. First basic understanding was achieved by scratch tests with diamond indenters by varying feed speed and analysing the resulting forces. Detailed investigations were accomplished by installing a tribometer within a scanning electron microscope (SEM). This setup allowed the analysis of the development of the resulting scratch groove.

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48

Aleksandrova, Valeriya, Neshka Manchorova e Svetlin Aleksandrov. "TRIBOLOGICAL TESTS OF RESIN-BASED COMPOSITE MATERIALS: A DESIGN STUDY". Journal of IMAB - Annual Proceeding (Scientific Papers) 27, n. 2 (21 aprile 2021): 3700–3706. http://dx.doi.org/10.5272/jimab.2021272.3700.

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Objective: The objective of our research is to study the tribological behaviour of two types of commercially available resin-based composite materials. Material and method: An original experimental model for tribological studies of dental materials in standard test conditions was applied. Two types of resin-based composite materials indicated for the treatment of dental caries in the distal area were used: a micro-hybrid resin-based composite material (Gradia Direct posterior); packable resin-based composite material (Filtek P60). Metal alloy (Duceralloy C) was used for positive control. Total 18 test samples (n=9 for each material) were subject to: micro scratch resistance test in 1N, 5N, 9N mode; friction resistance "Ball-on-Flat" test at 120,000/240,000 cycles loaded on 50N. Results: When the maximum load was applied, Gradia Direct posterior had higher values of scratch depths (40, 23 µm) than Filtek P60 (25,13 µm). The micro-hybrid composite exhibited less wear resistance that decreased with increasing time and friction cycles (13 µm after 30 min/120,000 cycles; 18 µm ether 60 min/240,000 cycles). The examined surfaces of the test specimens were visualized by optical microscopy after micro scratch and friction test and by 3D profilometry of all tested samples after 240,000 wear cycles. Conclusion: Results in this field might clarify the mechanisms of wear and provide additional information on the expected changes in the studied materials in clinical practice.

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49

de Souza, Rafael Gonçalves, Guilherme D´Aquino Pinho, F. J. P. Sousa, Márcio Celso Fredel e Orestes Estevam Alarcon. "Effect of Sense and Spacing in Parallel Scratches during Brittle Machining of Stoneware Tiles". Materials Science Forum 727-728 (agosto 2012): 640–45. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.640.

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Abstract (sommario):

Assuming that during the machining of stoneware tiles by flat grinding each grain on the abrasive wheel performs a single scratch, it is possible to simulate and analysis the effect generated by those employing esclerometry. This paper studied the effect between parallel scratches during brittle machining of stoneware tiles. Scratching tests were performed employing a CNC esclerometer; a Vickers indenter as abrasive tool; load of 10N by dead weight; three different configurations of sense in the same direction; three different configurations of spacing between the scratches incremented with a factor of 0.8, 1.0 and 1.2 times the average scratch width. The test samples were analyzed by optical microscopy and subsequent digital image analysis to quantify the worked area. The results showed variation of material removal as a function of the sense and spacing configuration. The sense configuration 1stR-3rdR-2ndR had the highest improve in material remotion. The spacing arrangement 1.2 remain with many not worked areas between the scratches, needing rework to remove this material. The configuration with 0.8 was found a redundancy of work specially when used with the sense configuration of 1stR-3rdL-2ndR.

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50

Brostow, Witold, Wunpen Chonkaew, Lev Rapoport, Yakov Soifer, Armen Verdyan e Yakov Soifer. "Grooves in scratch testing". Journal of Materials Research 22, n. 9 (settembre 2007): 2483–87. http://dx.doi.org/10.1557/jmr.2007.0307.

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Abstract (sommario):

For a number of polymers with a variety of chemical structures and different properties, we have performed scratch-resistance tests and investigated the profiles of the grooves formed using a profilometer. Three main kinds of material response are seen: plowing; cutting; and densification. The cross-sectional areas of the grooves include the groove and side top-ridge areas. The latter are smaller than the former, an indication of densification at the bottom and the sides of the groove; the effect can be connected to molecular dynamics simulations of scratch testing. The sum of the groove and top-ridge areas is the highest for Teflon, thus providing another measure of its poor scratch resistance. The Vickers hardness of the polymers was also determined. An approximate relationship exists between the hardness and the groove area. An unequivocal relationship between the hardness and the total cross-sectional area of the material displaced by the indenter is found. The resulting curve can be represented by an exponential decay function.

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