• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.1
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• pp.19-27
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• 1983

This paper deals with hardness and wear characteristics of ion-nitrided metal, and with ion-nitride processing which is concerned with the effects of added carbon content in gas atmosphere. A small optimal amount of carbon content in gas atmosphere increase compound layer thickness, as well as to increase diffusion layer thickness and hardness, and reduces wear rate when the applied wear load is small. It is found in the analysis that under small applied wear load, the critical depth where voids and cracks may be created and propagated is located at the compound layer, so that the abrasive wear where hardness is an important factor, is created and the existence of compound layer reduces the amount of wear. When the load becomes large, the critical depth is located below nucleation and propagation, is created and the existence of compound layer increase wear rate.

• Tribology and Lubricants
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• v.15 no.2
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• pp.141-149
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• 1999

Fracture, fatigue and wear characteristics of Al-Si alloy used for compressor are experimentally studied. Plane strain fracture toughness test is carried out using three point bending specimen. Fatigue test is performed under constant loading condition and wear test is carried out as a function of sliding velocity and applied load. To obtain the crack propagation characteristics and wear mechanism of Al-Si alloy, fracture and worn surfaces are investigated using SEM. It is verified that fracture and fatigue strength of Al-Si alloy are improved by the fine microstructure of alloy. The wear behavior and specific wear amount of Al-Si alloy are not dependent on the microstructure but on a function of the silicon content. Anodizing on the surface of Al-Si alloy, surface hardness and wear characteristics are improved.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.2
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• pp.210-230
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• 1995

To compare the wear resistance of four kinds of commercial acrylic resin teeth [SR-Orthosit PosterioresR(Ivoclar Co., Liechtenstein), Endura PosteriorR(Shofu Inc. Japan), trubyte IPN teethR(Dentsply International Inc., York,), Trubyte BiotoneR(dentsply Inermational Inc. Brazil) by means of the toothbrush abrasion method, the artificial resin teeth were embedded in epoxy resin with the occlusal surfaces aligned in one plane for a total of 40 blocks. There after, each lock was mounted in the arm of the toothbrush abrasion machine(K 236, Japan). Wear measurements were made on the three preconditioned states. Those were as follows : no treatment specimens, thermocycled specimens, and thermocycled specimens which were immeresed applied load of 400g during the buring the brushing cycle. At the end of the 30,000-stroke cycle, each specimen was removed, and weighed. The microhardness of four kinds of commercial resin teeth were determined by means of microhardness tester. Microhardness tests were performed on te no treatment specimens, thermocycled specimens, and thermocycled specimens with immersion in the denture cleansing solution. Finally, the comparison of thermal properties were perfomed using differential scanning calorimeter(DSC-1500). The following results were obtained : 1. In the case of no treatment teeth, the wear amount of endura Posterior(EN) was the greatest among the others(p<0.01), and the wear amount of three kinds of artificial resin teeth was increased in the order of Trubyte IPN teeth(IN), Trubyte Biotone(BN), SR-Orthosit Posteriores(SN) but there was no statistic significance(p>0.01). 2. The wear amount of Trubyte IPN teeth(IT) and Trubyte Biotone(BT), was increased due to thermocycling effect, but that of Endura Posteriores(ET) was decreased conversely(p<0.01). 3. Except for the SR-Orthosit Posteriores(STC), the wear amount of three kinds of artificial resing teeth(that is, ETC, ITC, BTC) was increased due to denture cleansing solution$(Cledent^R)$, but there was no statistic significance(p>0.01). But the wear amount of the SR-Orthosit Posteriores(STC) was the greatest among the others(p<0.01). 4. The wear amount of toothbrush was the greatest in case of contact with occlusal surface of SROrthosit Posteriores resin teeth(p<0.01). 5. the microhardness values(KHN) of the SR-Orthosit Posteriores was the highest among the experimental artificial resin teeth(p<0.01). 6. There was no relationship between microhardness valuse(KHN) and wear amount of four kinds of experimental artificial resin teeth(p<0.01). 7. The differential canning calorimetric property of four kinds of artificial resin teeth did not show endothermal or exothermal peak in the range of $100^{\circ}C$

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.1
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• pp.74-88
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• 1985

The wear becomes the most complicated cause of making various machineries short lives. In the studies by many scholors so far, the accurate and perfect methods to eliminate it completely are not found yet owing to many affected factors. On this view point of Depositional Wear, the wear test with seven different specimens from the part of frequent usage of which are carbon steel, nickel, copper, aluminum, zinc, lead and tin was attempted to make clear the relation between the wear of different metals and their melting point, crystal structure, sliding speed, load and lattice factors. The results of this study are summerized as follows; 1) Worn amount of each metal is maximum when each metal is same quality. 2) The easier becomes the the formation of solid solution in the course of friction proceeding, the more it results in worn amount of each metal. 3) The samer is each metal in crystal structure as well as lattice factor, the more it results in worn amount of each metal. These results might be of use in designing machineries, selecting materials and operating machineries.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.103-108
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• 2004

Carbon fiber reinforced composites(CFRP) were fabricated with phenolic resin matrix by hot press molding, and its surface was modified by the ion-assisted reaction process. When we tested the friction coefficient and wear rate variation and observed the effect of fibers with respect to friction and wear characteristics, the amount of pitch based carbon fiber was 45wt% and the average friction coefficient was the lowest at 0.12. When the amount of ion-irradiation was $1\times10^{l6}ions/cm^2$, the friction coefficient of the composites was about 0.12 and the wear mode was stable, whereas, the friction coefficient of the non-treated composites was about 0.16 and the wear mode was very unstable. But if the amount of ion-irradiation was $5\times10^{l6}ions/cm^2$$1\times10^{l6}ions/cm^2$ion-irradiation case.

• Anatomy and Cell Biology
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• v.51 no.4
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• pp.251-259
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• 2018

The aim of this study is to examine the correlation between tooth wear and age by quantitatively measuring maxillary first molar wear in children. A total of 150 maxillary dental models were analyzed in 30 subjects (male, 11; female, 19) with an age range of 6-14 years. Maxillary first molar wear were assessed based on area, volume and the shortest distance from the buccal occlusal plane to the central pit point (BCPH). The area and volume of the tooth cusps were measured at four different offset-plane heights (0.2, 0.4, 0.6, and 0.8 mm). Relationship between age and the amount of wear or BCPH were statistically analyzed. Correlation and regression analyses were also performed, and age estimation was obtained with linear regression analysis. Repeated measures analysis of variance (ANOVA) revealed significant differences between age and the amount of wear based on area, volume, and offset-plane height. Except age of 8 and 10, 12 and 14's 0.2-mm offset-plane-measured volume, all area and volume measurement of all ages and offset-plane height showed a significant amount of increase. Wear speeds were calculated using the BCPH. Among age and measurement variables, the correlation coefficient was strongest when the volume was measured from the 0.4-mm offset-plane. As age increases, the amount of wear, as quantified by area and volume measurements, also increases. According to this study, a regression equation that can be used for age estimation is follows: Age $(y)=0.16{\times}0.4V+0.85$ ($R^2=0.490$) using volume.

• Transactions of Materials Processing
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• v.26 no.3
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• pp.137-143
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• 2017

In this study, a wear test method was proposed to predict the wear life of the CrN layer coated on the surface of the press tools for manufacturing the auto-parts with ultra high strength steel (UHSS) with a tensile strength of 1.5 GPa. The pin-on-disc type wear test was carried out to confirm the feasibility and the reproducibility of the wear amount according to the test conditions such as the normal force, the sliding velocity, and the sliding speed. The test conditions were obtained from the finite element stamping analysis and the wear simulation. With the wear amount from the wear test, a prediction model of the wear depth in the CrN coating layer was proposed according to the test conditions with the design of experiments such as Taguchi method and the response surface method. The derived prediction model was then compared to the result of the Archard wear model, fully describing that the proposed model can effectively predict the wear life of the press tools for the auto-parts with UHSS.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.1
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• pp.96-104
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• 2001

This study was performed to compare the abrasiveness and wear resistance of several restorative materials occluding enamel and gold alloy. Intact labial surface of bovine incisor and the plain portion of type III gold alloy were used as plate specimens, and pin specimens were fabricated using $Artglass^{(R)},\;Targis^{(R)},\;Sculpture^{(R)}$. After two-body wear test using pin and plate model, amount of vertical height loss of plate and pin specimens were measured and statically analyzed. The amount of vertical height loss of plate specimens against pin specimens were measured by a roughness measurement instrument. The amount of vertical height loss of pin specimens against plate specimens were measured by an image analyzing program after taking scanning electron micrographs of pin specimens. The results were as following. 1. As fir the amount of enamel wear. gold group showed least amount of wear. There was no significant difference among Sculpture, Targis and Artglass groups(p<0.05). 2. As for the amount of gold wear Sculpture group standed first and Targis and Artglass group followed respectively, and there was significant difference between Sculpture and Artglass groups(p<0.05). 3. As for the amount of restorative materials against enamel, Artglass group showed greatest, and there was no significant difference among gold. Sculpture, Targis groups(p<0.05). 4. As for the amount of restorative materials against gold, Artglass group standed first and Targis and Sculpture group followed respectively, and there was significant difference among each groups(p<0.05).

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.143-150
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• 2007

Ring and cylinder bore wear may not be a problem in most current automotive engines. However, a small change in ring face and cylinder bore diameter can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blow-by and oil consumption in an engine. Therefore, by predicting the wear of piston ring face and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Here, the oil amount through top ring gap into combustion chamber is estimated as engine oil consumption. Furthermore, the wear theories of ring and cylinder bore are included. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. The wear data of rings and cylinder bore are obtained from three engines after engine durability test. The calculated wear data of each part are turn out to be around the band of averaged test values or a little below. It is shown that the important factor regarding oil consumption increasement is the wear of ring face.

• Transactions of Materials Processing
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• v.31 no.1
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• pp.11-16
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• 2022

In this paper, wear characteristics of PVD coatings were compared on the die surface for cold stamping of MART1470 steel sheet with the finite element analysis and the pin-on-disc wear test. Three types of PVD coatings (CrN, TiAlCrN, and MoS2TiCr(W)N) were considered for the tool surface made of STD11 material. The stamping process of an auto-body part was analyzed with the finite element method. Ranges of process variables for the wear test such as contact pressure, relative speed, and sliding distance were predicted from analysis results. In order to quantitatively analyze wear characteristics of each coating, the amount of wear was measured and compared according to process variables with the pin-on-disc wear test. The influence of each process variable was investigated and the wear characteristics of the three coating layers were quantitatively compared. It was confirmed that the wear characteristics of MoS₂TiCr(W)N coating were better than those of CrN and TiAlCrN. It was noted that the proposed prediction approach could predict and respond to the wear phenomenon occurring in the stamping process.