수복재료에 대합되는 의치용 레진치의 마모저항성 비교

이철영,정문규,Lee, Chul-Young,Chung, Moon-Kyu 대한치과보철학회 1999 대한치과보철학회지 Vol.37 No.3

The aim of this study was to compare wear resistance of resin denture teeth opposing various restorative materials. The wear resistance of conventional acrylic resin teeth(Trubyte Biotone) and three high-strength resin teeth(Bioform IPN, Endura, SR-Orthosit-PE) opposing different restorative materials(gold alloys, dental porcelain, composite resin) was compared. Wear tests were conducted with a sliding-induced wear testing apparatus which applied 100,000 strokes to the specimen in a mesio-distal direction under conditions of 100 stroke/min and constant loading of 1Kgf/tooth. Wear resistance of the resin denture teeth was evaluated by the following criteria : 1) wear depth, 2) weight loss, and 3) SEM observation. Results were as follows. 1. When opposed to gold alloys and composite resin, high-strength resin teeth showed superior wear resistance compared to acrylic resin teeth. But, in cases opposing dental porcelain, differences between the wear of the high-strength and acrylic resin teeth were not statistically significant (p<0.05). 2. When comparing wear resistance among high-strength resin teeth, opposing gold alloys, Endura was slightly more resistant and while in cases opposing dental porcelain, SR-Orthosit-PE was showed to be slightly resistant(p<0.05). 3. The wear of high-strength resin teeth was greater by 5 to 7 times when opposing porcelain and 2 to 3 times when opposing composite resin compared to gold alloys(p<0.05). 4. SEM observations of the wear surface showed that wear of resin teeth opposing gold alloys is a fatigue type of wear and wear of resin teeth opposing dental porcelain is fatigue and abrasion type of wear. Trubyte Biotone showed more severe fatigue type of wear than high-strength resin teeth. In conclusion, the use of dental porcelain should seriously be considered as restorative material in cases opposing resin denture teeth and improvement seems to be needed on resin teeth in the areas of wear resistance.

바닥재 마모에 따른 미끄럼 저항 변화

김정수 ( Jung Soo Kim ) 한국안전학회(구 한국산업안전학회) 2013 한국안전학회지 Vol.28 No.2

All most of floors can become less slip resistant with wear. The deterioration of slip resistance can often occur rapidly. So relatively new products can become hazardous within a short period of time. The main objective of this study was the comparison of slip resistance variations caused by traffic wear and accelerative wear. The second objective was to ascertain the effect of wear, and to find out the causes of slip resistance change. Although statistical differences were observed between results of traffic wear and accelerative wear, the trend of the variations of slip resistance caused by traffic wear and accelerative wear was very similar. The measured slip resistance of tested floor changed up to 29%(and 26.5%) after 100,000 steps(and 750 cycles). As the traffic wear and accelerative wear were progressed, the surface roughness of the tested floor became smoother, and so the floor became more slippery under the wet condition. The abraded (worn out) floor surface tended to become hydrophilic surface, while the new floor surface tended to show hydrophobic nature. This phenomenon would change the wettability of floor surface, and the wettability would affect the variation of slip resistance.

Laser Cladding Novel NiCrSiFeBW–CeO2 Coating with Both High Wear and Corrosion Resistance

Min Guo,Suiyuan Chen,Fanmin Shang,Jing Liang,Tong Cui,Changsheng Liu,Mei Wang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8

In order to obtain the high wear- and corrosion-resistant nickel based alloy coatings for laser remanufacturing fretting damaged metal parts which are serviced under high-temperature corrosion and wear conditions, a novel NiCrSiFeBW–CeO2alloy powder was designed by increasing the content of B and Si, adding tungsten and CeO2 using JMatpro software onthe basis of Ni60 alloy powder composition, and the NiCrSiFeBW–CeO2 coating was successfully cladded on 45# steelunder diferent laser energy area densities. The microstructure, wear and corrosion behaviors of the NiCrSiFeBW–CeO2coatings were systematically studied. The results show that novel NiCrSiFeBW–CeO2 coating produced by laser claddingnot only has no cracks but also has both high wear resistance and corrosion resistance due to some ultra-fne compoundparticle phases in situ generated in its structure. Among these phases, the B3Cr5, CrB4, (Cr, Ni)3C2, Cr7C3, W3Cr12Si5 and(Fe, Ni)5Si3 played a signifcant role in reinforcing the wear resistance of the coating, while the B3Cr5, W3Cr12Si5 and CrB4enhanced the corrosion resistance of the coating. The novel NiCrSiFeBW–CeO2 coating prepared under 100 J/mm2EADhas the best comprehensive performance, the wear loss is 7.53×10−5 mm3/N, the Ecorr is − 0.1738 V. Compared with Ni60alloy coating, the novel Ni-based coating not only has a better laser cladded formability but also similar wear resistance andbetter corrosion-resistance. It provides a reference for repairing fretting damaged metal parts by laser cladding the nickelbased coating with high wear and corrosion resistance.

Wear Particulate Matters and Physical Properties of ENR/BR Tread Compounds with Different Ratio of Silica and Carbon Black Binary Filler Systems

( Gyeongchan Ryu ),( Donghyuk Kim ),( Sanghoon Song ),( Hyun Hee Lee ),( Jin Uk Ha ),( Wonho Kim ) 한국고무학회 2021 엘라스토머 및 콤포지트 Vol.56 No.4

The demand for truck bus radial (TBR) tires with enhanced fuel efficiency and wear resistance have grown in recent years. In addition, as the issue of particulate matter and air pollution increases, efforts are being made to reduce the generation of particulate matter. In this study, the properties of epoxidized natural rubber (ENR) containing a silica-friendly functional group were evaluated by considering it as a base rubber and varying the silica ratio in this binary filler system. The results showed that the wear resistance of the NR/BR blend compound decreased as the silica ratio increased. In contrast, the ENR/BR blend compound exhibited an increase in wear resistance as the silica ratio was increased. In particular, the ENR-50/BR blend compound showed the best wear resistance due to the presence of several epoxide groups. Furthermore, we observed that for tan δ at 60℃, higher epoxide content resulted in the higher T_g of the rubber, indicating a higher tan δ at 60℃. On the other hand, it was confirmed that increasing the silica ratio decreased the value of tan δ at 60℃ in all compounds. In addition, we measured the amount of wear particulate matters generated from the compound wear. These measurements confirmed that in the binary filler system, regardless of the filler type, the quantity of the generated wear particulate matters as the filler-rubber interaction increased. In conclusion, the silica filled ENR/BR blend compound exhibited the lowest generation of wear particulate matters.

Wear Particulate Matters and Physical Properties of Silica filled ENR/BR Tread Compounds according to the BR Contents

( Gyeongchan Ryu ),( Donghyuk Kim ),( Sanghoon Song ),( Hyun Hee Lee ),( Jin Uk Ha ),( Wonho Kim ) 한국고무학회 2021 엘라스토머 및 콤포지트 Vol.56 No.4

The demand for truck bus radial (TBR) tires with enhanced fuel efficiency and wear resistance have grown in recent years. In addition, as the issue of particulate matter and air pollution increases, efforts are being made to reduce the generation of particulate matter. In this study, we investigated the effect of varying the content of butadiene rubber (BR) on the properties of the rubber compounds and the amount of particulate matter in the TBR tire tread compound. Furthermore, we utilized carbon black in the NR/BR blend compounds owing to its excellent compatibility, and we used silica in the ENR-25/BR blend compounds because it can interact chemically with epoxide groups. The NR/BR blend compounds and the ENR-25/BR blend compounds were evaluated by varying their BR content between 20 phr and 30 phr. The results showed that the ENR-25/BR blend compounds had superior wear resistance than the NR/BR blend compounds. This was caused by the interaction between silica and ENR. In addition, it was confirmed that the increased wear resistance as the BR content increased. Furthermore, compared to the NR/BR blend compounds, ENR-25/BR blend compounds exhibited a lower tan δ value at 60°C because silica was used as filler. This indicates a higher fuel efficiency. The measurement results for wear particulate matter showed that as increasing the BR content resulted in generation of less wear particulate matter. This was caused by the increased wear resistance. Moreover, the ENR-25/BR blend compounds with excellent filler-rubber interaction exhibited lower quantities of generated wear particulate matters as compared to the NR/BR blend compounds.

대기 플라즈마 용사법으로 제조된 철계 혼합 코팅층의 마모특성

黃昞哲,安志勳,李聖鶴,吳重錫 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.3

The objective of this study is to investigate the correlation between microstructure and the wear resistance of various ferrous blend coatings applicable to cylinder bores. Seven types of ferrous spray powders, two of which were stainless steel powders and the others were blend powders of ferrous powders mixed with Al_2O_3-ZrO_2 powders, were sprayed on a low-carbon steel substrate by atmospheric plasma spraying. Microstructural analysis of the coatings showed that iron oxides were formed in the austenitic (or martensitic) matrix by oxidation during spraying, while Al_2O_3-ZrO_2 oxides were mainly formed in the matrix for the blend coatings. The wear test results revealed that the blend coatings showed the better wear resistance than the ferrous coatings because they contained a number of hard Al_2O_3-ZrO_2 oxides. However, they had rough worn surfaces because of the preferential removal of the matrix and the cracking of oxides during wear. The STS 316 coating showed the slightly worse wear resistance than the blend coatings, but they showed the excellent wear resistance to a counterpart material resulting from homogeneous wear in oxides and matrix due to the smaller hardness difference between them. In order to improve the overall wear properties with consideration of the wear resistance of a counterpart material, the hardness difference between oxides and matrix should be minimized, while the hardness should be maintained up to a certain level by forming an appropriate amount of oxides.

Wear Mechanisms of Al₂O<SUB>3f</SUB>/SiC<SUB>p</SUB> Reinforced Al Metal Matrix Composites under Dry and Lubricant Wear Conditions at Room Temperature

Yi Qi Wang,Yu Shi,Foisal Ahmand Mirza,Ali Md. Afsar,Jung Il Song(송정일) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10

This study investigates the room temperature sliding wear mechanisms of Al₂O₃<SUB>f</SUB> and SiC<SUB>p</SUB> reinforced Al metal matrix composites (MMCs). The effects of fiber orientation and fiber to particle hybrid ratio on the wear behaviors at both the dry and lubricant conditions are discussed in details. The MMC specimens were fabricated by squeeze casting method with different hybrid ratios and fiber orientations. The tests were carried out by a pin-on-disk friction and wear tester at a constant sliding speed of 0.36 ㎧ (570 rpm) against a steel counter disk. The results of dry sliding tests showed that the F20P0 (unhybrid) MMCs with normal (N) orientation of fibers had better wear behaviors than those with planer-random (PR) orientation of fibers. However, for hybrid MMCs, the wear behavior was better for PR-orientation of fibers. On the contrary, the lubricant wear behaviors of F20P0 MMCs with PR-orientation of fibers were superior to those with N-orientation of fibers and the reverse lubricant wear behaviors were observed for hybrid MMCs. Finally, the scanning electron microscope (SEM) images of the wear surface and debris were used for investigating the modes of wear.

대기 플라즈마 용사법으로 제조된 Mo 및 Mo 혼합 코팅층의 미세조직과 마모특성

황병철,안지훈,이성학 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.3

The objective of this study is to investigate the correlation between the microstructure and wear resistance of various molybdenum blend coatings applicable to automotive parts. Five types of molybdenum spray powders, one of which was pure molybdenum powders and the others were blend powders of molybdenum powders mixed with brass, bronze, and aluminum alloy powders, were sprayed on a low-carbon steel substrate by atmospheric plasma spraying. Microstructural analysis of the coatings showed that they consisted of curved lamellar structures formed by elongated splats, while hard precipitates formed during spraying were relatively homogeneously distributed in the molybdenum matrix. The wear test results revealed that the blend coatings showed the better wear resistance than the pure molybdenum coating because they contained a number of hard precipitates. In particular, the molybdenum coating blended with bronze and aluminum alloy powders showed the excellent wear resistance, together with the excellent wear resistance of a counterpart material, resulting from the presence of hard precipitates and their homogeneous wear. Therefore, in order to improve the overall wear properties with consideration of the wear resistance of a counterpart material, appropriate spray powders should be blended with molybdenum powders to form hard precipitates in the coatings of this study.

유동성 복합레진의 마모저항성에 관한 연구

윤연희,김정욱,이상훈,한세현 大韓小兒齒科學會 2002 大韓小兒齒科學會誌 Vol.29 No.2

시술시간을 줄이는데 유리한 재료인 유동성 복합레진을 유구치부에 사용하려고 고려할 때 중요한 물성 중 하나는 마모저항성이다. 이 연구의 목적은 유동성 복합레진의 마모저항성을 일반복합레진의 마모저항성을 비교하는 것이다. 실험에 사용된 유동성 복합레진으로 1군에서는 Arabesk flow (VOCO, Germany), 2군에서는 Tetric flow (Vivadent, Liechtenstein), 3군에서는 Aeliteflow (Bisco, U.S.A), 4군에서는 Filtek flow (3M Dental Co, U.S.A)을 사용하였으며 대조군으로 사용한 5군의 복합레진은 Z100 (3M Dental Co, U.S.A)이었다. 시편들(n=10)은 두께 2mm, 지름 5mm의 원통모양으로 제작하여 마모시험 전 37℃의 증류수에서 7일 동안 담가 놓았다. 제1소구치와 레진시편을 MTS 시스템에서 2Hz로 50,000회 접촉, 마모시켰다. 마모시험시 lateral excursion은 0.4mm, 교합력은 2-100N의 조건이었다. 마모시험후 마모된 부피, 최대마모깊이, 재료자체의 표면경도를 측정하였고 마모되지 않은 표면과 마모가 일어난 표면을 주사전자현미경으로 관찰하였으며 다음과 같은 결과를 얻었다. 1. 마모된 부피는 3군에서 가장 적었고 4군에서 가장 많았으며 3군<1군<2군<5군<4군의 순서로 증가하였다. 2. 3군, 1군, 2군, 5군이나 4군에 비해 통계적으로 유의하게 마모부피가 적었다(P<0.05). 그러나, 3군, 1군, 2군 사이에서와 5군, 4군 사이에서는 각각 통계적으로 유의한 차이가 없었다. 3. 최대마모깊이는 1군에서 가장 낮았고, 4군에서 가장 깊었으며 1군<3군<5군<2군<4군의 순서로 증가하였다. 4. 5군의 표면경도는 다른 유동성 복합레진군에 비해 통계적으로 유의하게 높았으나(P<0.05). 마모부피나 최대마모깊이와는 통계적으로 유의한 상관관계를 보이지 않았다. 5. 마모되지 않은 표면과 마모가 일어난 표면을 주사전자현미경으로 관찰한 결과, 유동성 복합레진군과 5군 사이에 마모양상이 다르게 나타나는 것을 볼 수 있었다. When we use the flowable resin on the primary molars for quick handling, one of the most important property is the wear resistance. This study was performed to compare the wear resistance characteristics of four flowable composite resins [Arabesk flow (group 1), Tetric flow (group 2), Aeliteflow (group 3), Filtek flow (group 4)] to that of one control composite resin [Z100 (group 5)]. Specimen discs(n=10), 10mm wide and 2mm thick, were stored in distilled water at 37℃ for 7 days prior to testing. The specimens were subjected to 50,000 strokes at 2Hz on the MTS system. During the test, the following parameters were maintained: the ;atera; excursion at 0.4mm, occlusal force at 2-100N with a force profile in the form of a half sine wave. The measurements of volume loss, depth of wear, and Vicker's hardness number of composite resins, and SEM obserbations of the polished and abraded surfaces were established. One-way ANOVA and Scheffe's multi-ple comparison test were employed to detect statistically significant differences among the flowable composite resin group and the control composite group at P<.05. The following results were obtained: 1. Group 3 showed the least volume loss, while group 4 showed the greatest. The mean volume loss increased in the following order: group 3<group 1<group 2<group 5<group 4. 2. Group 3, group 1, and group 2 showed significantly lesser volume loss compared to group 5 and group 4(p<0.05). However, There was no statistically significant difference among group 3, group 1 and group 2. There was no statistically significant difference between group 5 and group 4. 3. Group 1 showed the shallowest depth of wear, while group 4 showed the deepest. The mean depth of wear increased in the following order: group 1<group 3<group 5<group 2<group 4. 4. Group 5 showed significantly highest hardness value compared to the flowable composite resin groups(p<0.05), but there was no correlation between wear resistance and Vickers hardness number. 5. SEM observation of the unworn and worn surfaces revealed the differences in the wear appearance between the flowable composite resin groups and the control.

An analysis of the main factors on the wear of brushes for automotive small brush-type DC motor

Wae-Gyeong Shin,이수홍 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.1

Some critical components in motors and generators have sliding electrical contacts. Electrical brushes are commonly used in those contact points to conduct current between the stationary and moving parts of a motor. Brushes are exposed both to mechanical and electrical loading. In this paper, studies on the wear of brushes against copper commutator were briefly reviewed. The main influential factors of brush wear are associated with both mechanical and electrical wear. Brush wear is affected by various factors including temperature,material properties, sliding speed, contact force, and interfacial and environmental conditions. The mechanical wear of brushes is proportional to the brush spring pressure and sliding speed, while the electrical wear of brushes is associated with current and contact voltage drop. To characterize the wear, a brush wear test machine was designed, and influential factors were measured such as electrical contact resistance, temperature, wear mass loss, and so on. The wear tests were processed using a small brush type automotive DC motor. The main objective of this study is to investigate the effects of the wear behavior of copper-graphite brushes in a small brush-type DC motor. The variable conditions are with and without electrical current by changing the brush spring pressure and sliding speed, and the results are electrical contact resistance, voltage drop, brush surface temperature rise, and so on. Brush wear greatly changes with electrical current. This shows that the high current not only produces more Joule heating but also causes an increase in voltage drop, which will result in additional Joule heating.