• Design & Manufacturing
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• v.13 no.2
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• pp.44-48
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• 2019

Motor core products are used as materials for electrical steel sheets and cold-rolled steel sheets according to the performance of motors. The cemented carbide material of the mold punch applied to the motor core material causes many troubles due to abrasion and burr problem. The selection of these materials has a great effect on the production life, mass production, product quality as well as mold life. The cemented carbide applied to the products of the motor core is recognized as a very important part. In this study, cold rolled steel sheet was applied to motor core SCP-1 steel 1.0mm, and The effects of abrasion and punching oil on the shear process were investigated for the selection of cemented carbide. Experiments were conducted to select and apply cemented carbide only for the motor core punch optimized for cold rolled steel. The results showed that the cemented carbide material of $CDK3^{***}$ produced the least wear and burrs.

• Elastomers and Composites
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• v.57 no.2
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• pp.40-47
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• 2022

The effects of maleic-anhydride-grafted polypropylene (PP-g-MAH) and montmorillonite (MMT) on the wear resistance of polypropylene (PP) were investigated. The surface of MMT was modified with 3-aminopropyltriethoxysilane, and the interfacial interaction between PP and MMT was improved using PP-g-MAH. Fourier-transform infrared spectroscopy was used to confirm that silane was grafted on the surface of MMT. The Taber abrasion test and scanning electron microscopy were used to determine the wear resistance and observe the surface morphology of PP, respectively, after wear testing. Energy-dispersive X-ray spectroscopy was used to compare the effects of PP-g-MAH and silane modification of MMT on the dispersion of MMT. The results indicated that silane was successfully grafted onto the surface of MMT. Moreover, the wear resistance of PP was improved by the addition of MMT. The wear resistance of PP composites comprising silane-modified MMT and PP-g-MAH was higher than those of other PP composites. This was attributed to silane improving the interfacial interaction between MMT and PP.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.34-41
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• 2020

Ready-mixed concrete is unconsolidated concrete typically transported to construction sites by using mixer trucks. A proper rotation of concrete is necessary to prevent its solidification in mixer trucks during transport: in accordance with the manufacturing method and quality inspection prescribed in KSF4009, this movement is maintained after the manufacturing of concrete in professional production plants and the addition of water, solid materials, and admixtures. Unfortunately, mixer truck parts wear out over long periods of time. In order to improve the wear resistance of the main part of mixer trucks, we used a steel plate with good wear resistance or partially added a reinforcement plate. In this study, we first tested the properties of concrete (as required for the DEM), and then carried out mixing and discharge simulations to define the actual operating conditions of mixer trucks. For each condition, we calculated the amount and location of wear. The reliability of our results was finally verified by comparing them with the measurement values. Overall, this study provided basic data for an optimal design of mixer trucks: one that would reduce the vehicles' weight and production costs.

• Journal of Periodontal and Implant Science
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• v.29 no.1
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• pp.209-231
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• 1999

Even though titanium(Ti) and its alloys are the most used dental implant materials, there are some problems that Ti wears easily and interferes normal osteogenesis due to the metal ions. Ti coated with bioactive ceramics such as hydroxyapatite has also such problems as the exfoliation or resorption of the coated layer, Recent studies on implant materials have been proceeding to improve physical properties of the implant substrate and biocompatibility of the implant surfaces. The purpose of the present study was to examine the physical property and bone tissue compatibility of bioinert nitrides ion plated Ti, Button type specimens(14mm in diameter, 2.32rrun in height) for the abrasion test and cytotoxicity test and thread type implants(3.75mm in diameter, 6mm in length) for the animal experiments were made from Ti(grade 2) and 316LVM stainless steel. Ti specimens were ion plated with TiN, ZrN by the low temperature arc vapor deposition, and the depth profile of the TiN/Ti, ZrN/Ti ion plated surface was examined by Auger Electron Spectroscopy. Three kind of button type specimens .of TiN/Ti, ZrN/Ti and Ti were used for abrasion test, and HEPAlClC7 cells and CCD cells were cultivated for 4 days with the specimens for cytotoxicity test. Thread type implants of TiN/Ti, ZrN/Ti, Ti, 316LVM were implanted on the femur of 6 adult dogs weighing 10kg-13kg. Two dogs were sacrified for histological examination after 45 days and 90 days, and four dogs were sacrified for the removal torque test of the implant') after 90 days. The removal torque force was measured by Autograph (Shimadzu Co., AGS-1000D series, Japan). Abrasion resistance of TiN/Ti was the highest, and that of ZrN/Ti and Ti were followed. The bioinert nitride ion plated Ti had much better abrasion resistance, compared with Ti, In the cytotoxicity test, the number of both cells were increased in all specimens, and there were no significant difference in cytotoxic reaction among all groups (p>0.1), In histological examination, 316LVM showed the soft tissue engagement in interface between the implant and bone, but the other materials after 45 days noted immature new bone formation in the medullary portion along the implant surface, and those after 90 days showed implant support by new bone formation in both the cortical and the medullary portion, The removal torque force of Tilv/Ti showed significantly higher than that of Ti(p(O,05). The difference in removal torque force between TiN/Ti and ZrN/Ti was not significant(p>0.05), and that of 316LVM was lowest among all groups(p<0.05). These results suggest that bioinert nitrides ion plated Ti can resolve the existing problems of Ti and bioactive ceramics, and it may be clinically applicable to human.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.4
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• pp.21-28
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• 2014

In this study, evaluated ware the strength and durability of the vegetated water purification channel concrete to which recycled aggregates, hawang-toh and jute were applied. Box-Behnken method of response surface analysis in statistics was applied to the experimental design. Experimental variables are as follows, recycled coarse aggregates, hawang-toh, blast-furnace slag and jute fiber. In the experiment, conducted were the tests of compressive strength, chloride ion penetration, abrasion resistance and impact resistance the replacement rate effects of the recycled aggregates, blast-furnace slag and hwang-toh on the performance of vegetated water purification channel concrete were analyzed by using the response surface analysis method on the basis of the experimental results. In addition, an optimum mixing ratio of vegetated water purification channel concrete was determined by using the experimental results. The optimum mixing ratio was determined to be in 10.0% recycled coarse aggregates, 60.0% blast-furnace slag, 10.1% hwang-toh and 0.16% jute fiber. The compressive strength, chloride ion penetration, abrasion rate, and impact number of fracture test results of the optimum mixing ratio were 24.1 MPa, 999 coulombs, 10.30 g/mm3, and 20 number, respectively.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.51-56
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• 2007

Pantograph of the electric train is the important part receiving current by adhereing contact wire. Wearing rate of pantograph or contact wire is changed by the type of pantograph and material of adhering part. In special, the weather influences the relative wearing rate and wearing type of pantograph Slider and Contact wire with steep wearing in arc and life cycle of pantograph slider. Presently, the weather causes side-wearing and over-wearing of pantograph slide installed in electric train. So it is difficult to manage and operate the electric train. Although the quality of slide using in line4 vehicle was finished the test in line 2 vehicle experimentally, it has to apply after pantograph is installed in some electric trains and check the influence in it and contact wire. It is because line4 section is very different from line2 section. Experimental application is the sequence to certify the safety and abrasion resistance importantly by enlarging experimental application with increase of the experimental electric train. The lenth of line4 in Seoul Metro is 71.5[km]. It is long section. The line is mixed DC 1,500[V] section and AC 25,000[V] section. It has underground section of 41.5[km] and ground section of 30[km]. Ground section is about 42% and receives much influence in the rain during the rainy season. After experimental application we found that this pantograph slide has twice as much abrasion resistance despite a little deviation and found the occurrence probability of arc and side-wearing is decreased considerably.

• Advances in concrete construction
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• v.13 no.1
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• pp.101-111
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• 2022

The rapid development of the construction industry in the world causes a rapid increase in the consumption of aggregate resources, which leads to the depletion of existing aggregate reserves. The use of recycled aggregate in the production of concrete and mortar may be a good solution to reduce the use of natural raw materials and to reduce demolition waste in the environment. In this study investigating the use of recycled aggregate in mortar production, mortar mixtures were produced by substituting 0%, 25%, 50% and 100% fine recycled aggregate (FRA) instead of natural aggregate. The effect of 20% and 40% fly ash (FA) substitutes on cement mortar performance was also investigated. Compressive and flexural strength, drying shrinkage, abrasion resistance, water absorption and capillary water absorption were investigated on the produced mortars. The increase in the use of FRA reduced the compressive and flexural strengths of mortars. While the capillarity coefficients, water absorption, rapid chloride permeability and drying shrinkage of the mortars increased with the increase in the use of FRA, the effect of the use of fly ash on the rate of increase remained lower. The increased use of FRA has improved abrasion resistance as well.

• Korean Journal of Materials Research
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• v.12 no.5
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• pp.407-413
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• 2002

Eutectic high chromium cast irons containing 17%Cr and 26%Cr were produced for this research by making each of them solidify unidirectionally. Abrasion wear test against SiC or $Al_2$O$_3$bonded paper was carried out using test pieces cut cross-sectionally at several distances from the chill face of castings. The wear resistance was evaluated in connection with the parameters such as eutectic colony size($E_w$), area fraction of boundary region of the colony($S_B$) where comparatively large massive chromium carbides are crystallized and, average diameter of chromium carbides in the boundary region($D_c$). The wear rate($R_w$), which is a gradient of straight line of wear loss versus testing time, was influenced by the type and the particle size of the abrasives. The $R_w$ value against SiC was found to be larger than that against A1$_2$O$_3$under the similar abrasive particle size. In the case of SiC, the $R_w$ value increased with an increase in the particle size. The $R_w$ value also increased as the eutectic colony size decreased, and that of the 17%Cr iron was larger than that of the 26%Cr iron at the same $E_w$ value. Both of the $S_B$ and $D_c$ values were closely related to the $R_w$ value regardless of chromium content of the specimens. The $R_w$ values of the annealed specimens were greater than those of the as-cast specimens because of softened matrix structures. As for the relationship between wear rate and macro-hardness of the specimens, the hardness resulting in the minimum wear rate was found to be at 550 HV30.

• Journal of dental hygiene science
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• v.10 no.5
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• pp.373-378
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• 2010

To test the effects of representative fluoride vanishes-1.23% APF gel and 5% NaF Fluoride Varnish-on the surface structure of pit and fissure sealant, this study classified samples of pit and fissure sealant into five groups: Group I deposited in distilled water for ten minutes, Group II treated with APF gel for one minute, Group III treated with APF gel for four minutes, Group IV treated with Fluoride Varnish for one minute, and Group V treated with Fluoride Varnish for four minutes. An abrasion test was carried out to measure changes in weight, along with observation of the surface structure by using an optical microscope, consequently drawing the following conclusions. 1. The results of the abrasion test using pit and fissure sealant, Concise, showed that Group III had the reduction in weight more increased than Group I and that Group V had less reduction in weight (p<0.05); the results of the abrasion test using Eco-S showed Group III had the reduction in weight more increased than Group I and that Group V had less reduction in weight (p<0.05). 2. The results of observation using an optical microscope showed that application of APF gel made the filler remarkable due to loss of substrate and that Group III treated with APF gel for four minutes had the toughest surface, followed by Group II treated with APF gel for one minute, Group I deposited in distilled water for ten minutes, Group IV treated with Fluoride Varnish for one minute, and Group V treated with Fluoride Varnish for four minutes.

• Journal of the Semiconductor & Display Technology
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• v.6 no.2 s.19
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• pp.25-28
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• 2007

Electroless Ni-P coating is widely used for chemical, electronic, and semiconductor equipment parts because of its corrosion resistance. The incorporation of chemically-inert PTFE particles into the Ni-P films improves properties such as, non-stick, anti-adhesive and better corrosion resistance. However, soft PTFE particles degrade the hardness, wear and abrasion resistance. In this study, effects of PTFE and W addition to the Ni-P-coatings were compared by the XRD, SEM, sheet resistance, contact angle, and microhardness measurements. The change in sheet resistance was negligible, but contact angle was doubled by the addition of PTFE and W. The microhardness was lower for Ni-P-PTFE, but higher for Ni-P-PTFE-W coatings, compared to that of Ni-P coatings.