Temperature effects on the dry sliding wear of Al₂O_3f/SiC_p/Al MMCs with different fiber orientations and hybrid ratios

Wang, Y.Q.,Song, J.I. Elsevier 2011 Wear: An international journal on the science and Vol.270 No.7

<P><B>Abstract</B></P><P>Al<SUB>2</SUB>O<SUB>3</SUB> fiber (Al<SUB>2</SUB>O<SUB>3f</SUB>) and SiC particle (SiC<SUB>p</SUB>) hybrid metal matrix composites (MMCs) were manufactured in a squeeze casting method and investigated for their mechanical and wear properties at elevated temperatures of 100°C and 150°C. The pin specimens had different ratios of fiber to particle content but their total weight fraction was constant at 20wt.%. Dry sliding wear tests were conducted with a pin-on-disk friction and wear tester. The morphologies of the worn surfaces were examined using a scanning electron microscope (SEM) to observe the wear characteristics and investigate the wear mechanism. An optical microscope (OM) was used to examine the precipitations of the MMCs after wear tests under different temperatures. The grown precipitations improved the hardness of the matrix material during the wear tests at 150°C. Thus, the wear resistance was enhanced at 150°C due to the precipitation strengthening of the FeSiAl<SUB>5</SUB>. Furthermore, the tests results revealed that the wear resistance of normal (N) MMCs was superior to that of planer random (PR) MMCs as the PR-fibers were easily pulled out whole from the worn surface. The results of this investigation showed that the wear resistance of dry sliding wear decreased as the SiC<SUB>p</SUB> content and increased at 100°C and 150°C, independently of the fiber orientation.</P>

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.

Harris-Galante 비구컵의 polyethylene liner 마모

장준동 ( Jun Dong Chang ),정수원 ( Soo Won Jeong ),최수중 ( Soo Joong Choi ),장호근 ( Ho Guen Chang ),이창주 ( Chang Ju Lee ) 대한고관절학회 1997 Hip and Pelvis Vol.9 No.2

There were many investigations about the polyethyiene wear rate and the factors which influence the wear. However, wear rate was different among studies and the factors that predispose to rapid wear are not definitely determined as well. Purposes of the study were to measure the amount and rate per year of linear wear of the polyethylene(PE) of the Harris-Galante porous(HGP) cups using the computer base technique and to evaluate the factors which influence the linear wear rate and the influence of the linear wear rate to the resu)t of the THA. Wear amount, wear direction, and cup position were measured. From the standard AP radiograph, two center points are selected at the head and the margin of the cup using a digitizer. Linear wear was defined as distance from the center of the head to the center of the outer shell. The computer system and software convert the data points after correction for magnification into two circles. The measurement of wear using the computer base technique was effective and the mean rate of linear wear was 0.15+0.18mm. Linear wear rate correlated with age, size of cup, thickness of liner, inclination of cup, and osteolysis, but not with the weight, diagnosis, sex, and site. The incidence of osteolysis of the femur was significantly higher in the cups which had 0.15mm/year of wear or more. It is necessary to observe more carefully the patients who had 0.15mm/year of wear or more. Our study aiso suggested that the alternatives of the bearing surface should be considered in younger patients.

치과용도재에 의한 법랑질 마모에 관한 연구

이영국,이선형,양재호,정헌영,Lee, Young-Kook,Lee, Sun-Hyung,Yang, Jae-Ho,Chung, Hun-Young 대한치과보철학회 1999 대한치과보철학회지 Vol.37 No.1

Dental porcelain is one of the materials of choice for restoration where esthetics is of concern, but has a considerable potentials of wear. The wear of enamel is variable when opposed by different porcelain systems and surface conditions, and the exposed dentine and opaque porcelain due to clinical failure is expected to have high potentials of wear. The purpose of this study was to investigate the wear effects of self-glazed, polished incisal porcelain. polished dentine and opaque porcelain against human enamel in the laboratory by use of a pin-on-disk type wear tester. 4 types of dental porcelain($Vita-{\Omega}$, Ceramco-II, Vintage powder $Vita-{\alpha}$ of In-Ceram system) and type IV gold alloy as cotrol group were used for test specimens. Intact buccal cusps of maxillary premolar were used for enamel specimens, and the cusp converged to a point and was devoid of visible abrasion, caries, decalcification. The upper part was the cusp of a maxillary premolar and the lower part was a porcelain specimen. The enamel wear was deter-mined by weighing the cusp before and after each test. Surface profilometer was used to quantitate wear of the porcelain specimens. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces. The results were as follows : 1 Self-glazed porcelain produced more enamel wear than polished porcelain, especially the enamel wear of $Vita-{\alpha}$ self-glazed porcelain was 3.2 times more than that of other groups. 2. Opaque porcelain produced least porcelain wear, $Vita-{\alpha}$ self-glazed porcelain produce greatest porcelain wear, but there was no statistically significant difference between the groups(p>0.05). 3. The enamel wear of dentine porcelain was 3.8 times more than that of polished inisal porcelain(p<0.05), and the enamel wear of opaque porcelain was 1.9 times more than that of polished inisal porcelain, but there was no statistically significant difference between the groups(p>0.05) 4. Overglazed porcelain produced less enamel wear than self-glazed porcelain, and more enamel wear than polished porcelain, but there was no statistically significant difference between the groups(P>0.05). 5. The hardness number of $Vita-{\Omega}$ dentine and Ceramco-II opaque porcelain was larger, but that of Vintage dentine and $Vita-{\alpha}$ self-glazed porcelain was similar to other groups. 6. Examination of SEM photographs revealed that overglazed porcelain had smoother surface than self-glazed porcelain, and self-glazed porcelain had smoother surface than polished porcelain. Much polishing scratches and larger porosities were observed on the opaque porcelain specimen, and much polishing scratchess and small porosities were observed on the dentine porcelain specimen.

Wear depth model for thin tubes with supports

Kim, Hyung-Kyu,Lee, Young-Ho Elsevier 2007 Wear: An international journal on the science and Vol.263 No.1

<P><B>Abstract</B></P><P>A wear depth prediction model is proposed for thin tubes worn by a contact with supports. It has the form of D˙=Kw˙ where D˙ and w˙ are the wear depth and the energy density rates, respectively; <I>K</I> is a wear coefficient with the unit of Pa<SUP>−1</SUP>. Two kinds of experiments, i.e. sliding and sliding/impact are conducted with the fuel rod tubes and the transversely concave-contoured supports under room temperature and air/water environments. The applied sliding amplitude was 50–100μm and the contact normal force was 10–50N in the sliding wear experiment. Impact force of around 30N was applied in the sliding/impact wear experiment. It was found that a linearity between D˙ and w˙ exists at the same contact normal force condition. In the sliding wear experiments, <I>K</I> is larger in the air than in the water environment. It was verified that the addition of an impact is detrimental to a wear failure than a sliding wear only. It is thought that <I>K</I> can represent a wear resistance parameter in the point of the wear depth when the wear mechanism is similar. The influence of wear debris dispersion behaviour on the present model is discussed.</P>

에어로빅복의 착용감에 관한 연구

오순,박승순 경원전문대학 1995 論文集 Vol.17 No.1

To investigate the physiological responses of the human body and the subjective Sensation in accordance with material for aerobic apparel, its worn area and exercise experiences, this study conducted the experimentation of the wearing of aerobic wear manufactured of two kinds of textile material, such as nylon/Polyurethan(N/PU), and cotton/polyurethan/aclylic(C/PU/AC), which were marketed, under the conditions of the winter room environment such as 17+2C at temperature, 65+5% /R.H at humidity, and 0.25 +l.Om/sec at air current. This study was intended for the group of women in the 30s. 1. In point of the entire distribution of their skin temperature rose as the amount of their exercise increased, droped at time of sweating, and then showed an increasing trend at time of rest again. C/PU/AC showed a little higher distribution of skin temperature on the human body in terms of materials for aerobic wear. In relation to whether or not they were wearing underpanties, the women wearing underpanties showed a low skin temperature. Temperature inside underpanties showed a tendency similar to the skin temperature. 2. The amount of local sweating absorbed on filter paper was shown to be in order of forehead>large pectoral muscle>forearm>femoral. And it was shown to be in order of aerobic wear materials. In conjuntion with whether or not woman were wearing underpanties, those woman were wearing underpanties showed a higher amount of sweating. 3. A thermal sensation was shown to have a high positive correlation with a humid sensation. Senses associated with the comfort sensation are thermal sensation, humid sensation, touch. As a result, it can be seen that those wearing aerobics wear feel hot if its humidity is high and they feel uncomfortable in case its touch is bad.

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.

A real time wear measurement system for tripod type constant velocity joints

Kim, Seong Han,Kim, Dong Wan,Chu, Chong Nam Elsevier 2019 Precision engineering Vol.56 No.-

<P><B>Abstract</B></P> <P>A real-time wear measurement system for tripod type Constant Velocity (CV) joints is proposed in this study. Adhesive wear on tripod type CV joints is very crucial to the life time of CV joints but it is very difficult to measure the wear depth of a tripod type CV joint separate from the drive shaft assembly. The wear measurement system developed in this study can measure the wear depth of a tripod type CV joint in real-time as it applies kinematics and forces to the CV joint.</P> <P>In order to apply the same motions as the motions of an actual CV joint, kinematics of the CV joint has been analyzed. As a result, reciprocating stroke and yaw motions have been completely implemented in the system. The wear measurement system comprises four parts. The first part is for applying normal forces to a set of spherical roller and housing track. One servo motor, spur gear and ball screw sets were employed to generate and augment the normal forces. The second and third parts are for applying reciprocating stroke and yaw motions, respectively. These parts synchronize with each other to make the same motion profiles as the actual CV joint. The fourth part is for measurement. This part consists of load cell and rotary encoder to measure the surge normal forces caused by the flaking phenomena and the wear depth caused by the adhesive wear. In the case of the encoder, the wear depth is augmented by the ball screw and spur gear sets so 0.18°/μm of measurement resolution can be achieved.</P> <P>For the validation of the system, a tripod type CV joint was selected, and its wear depth was measured by the system and the results were compared with the wear depth measured by a profilometer.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The real time measurement system is able to perfectly implement the motion of CV joints. </LI> <LI> The same kinematics and forces of a tripod type CV joint can be applied to the system. </LI> <LI> The set of spur gear and ball screw was employed to augment the wear depth. </LI> <LI> 0.18 degree/μm wear depth accuracy can be achieved by the system. </LI> <LI> Compared to the wear depth results by a profilometer, the system provides very accurate wear depth results. </LI> </UL> </P>

Effect of impact frequency on the wear behavior of spring-supported tubes in room and high temperature distilled water

Lee, Young-Ho,Kim, Hyung-Kyu,Jung, Youn-Ho Elsevier 2005 Wear: An international journal on the science and Vol.259 No.1

<P><B>Abstract</B></P><P>Sliding and impact/sliding wear tests have been performed in order to evaluate the wear properties of nuclear fuel rods in room and high temperature distilled water. In this study, tests have been conducted at a normal load of 10N, sliding amplitudes of 10–100μm and four impacting frequencies of 0, 5, 10 and 30Hz by using a spacer grid spring of fuel assemblies. The results indicated that the wear volume of the fuel rods is rapidly increased with an increasing impact frequency and slip amplitude. This is mainly concerned with the behavior of the generated wear particles on the worn surfaces, which is affected by the impacting frequency of the spring specimen. Based on the observations of the worn area, the wear particles in the room temperature water remained in the contact surfaces below 10Hz of an impact frequency even though the water fluctuation at the contact surfaces due to the impact motion was expected to easily remove the wear particles. However, the wear volume was decreased by increasing the test temperature. This seems to be closely related to the changed properties of the spring stiffness in the high temperature water and the formation of the load-bearing layers rather than the changed material properties on the worn surface. Based on the present results, the detailed mechanisms of the wear particle behavior according to the test conditions were investigated and the relationship between the spring characteristics and the wear behaviors in high temperature distilled water is discussed.</P>

Effect of the worn status of wheel/rail profiles on wheel wear over curved tracks

Jie Kou,Jimin Zhang,Hechao Zhou,Chengping Wang,Lixia Sun 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3

The worn status of wheel/rail profiles could change the wheel-rail contact and influence the wear rates of the wheel and rail. Worn wheel profiles of a Chinese intercity train and the worn rail profile of curved tracks were taken into account in this work. According to the dynamics model of the vehicle, teh wheel-rail three-dimensional steady-state rolling contact model, and the Archard wear model, a new fast calculation method of wheel wear rate was proposed. Simulation results show that obviously severe wear would distribute in the flange when the wheel and rail were worn. The side wear of rail gauge corner will seriously aggravate the wear of new wheel flange. The wear of the wheel is serious for teh worn wheel in the initial phase of service. Therefore, the re-profiling of wheels and rails should be scheduled cooperatively, and the wear of flange in the initial phase of service should addressed.