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Microstructures of 3 mol% Y2O3-ZrO2 (3Y-TZP) with systematically varying porosity up to about 15% were produced by sintering. Hardness and fracture toughness of the ceramics as well as the amount of tetragonal, cubic and monoclinic phase were measured. Wear tests were carried out on the different self-mated microstructures under dry reciprocating sliding contact using ring-on-block geometries in air at five different contact temperatures up to 500°C. The microstructures and worn surfaces were extensively analysed using scanning electron microscopy (SEM) and X-ray diffraction techniques. The experimental results revealed a reduction of the amount of wear (independent of porosity) by more than one order of magnitude compared with room temperature if the test temperature was increased to 250°C. Between room temperature and 250°C, wear increased with increasing porosity while at 500°C the highest wear was measured on the dense structure. Microscopic observations showed that plastic deformation, surface layers consisting of compacted wear debris and also intercrystalline, transcrystalline or delamination type fracture influenced friction and wear. 相似文献
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Sadao Asanabe 《Tribology International》1987,20(6):355-364
Fine ceramics are expected to be applied as new materials to many tribological components because of their superior heat resistance and corrosion resistance and their high hardness. In this paper, wear and frictional test results from applications of these components in machines are given and the capabilities of fine ceramics are described. 相似文献
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Friction experiments were conducted on four kinds of ceramics (SiC, Si3N4, Al2O3 and ZrO2) against themselves in water under different contact pressures and sliding velocities. The variations of friction coefficients
as a function of sliding distance, and the effects of mean contact pressure and sliding velocity on friction coefficients
were shown. Friction coefficients lower than 0.03 were observed under a certain combination of mean contact pressure and sliding
velocity for each material. The friction coefficient suddenly increased when the mean contact pressure was above a threshold
value, which depended on both sliding velocity and the material of sliding pairs. SiC had a higher threshold value than the
other three ceramics at every sliding velocity investigated.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Tests on self-mated Si3N4- and SiC-based ceramics as well as ceramic-ceramic composites were performed in an Amsler-type wear tester under dry and water-lubricated rolling conditions with 10% slip. Under dry friction, wear coefficients of the materials varied by four decades. Unlubricated wear coefficients below 10−7 mm3/(N.m), defined as a practical limit for applicability, can be achieved with Si3N4-TiN below 775 MPa and with HIP-SiC below 750 MPa. HIPped Si3N4 and hot-pressed SiC-TiC under dry friction exhibit a small dependency of wear coefficient on Hertzian pressure, with wear coefficients below 10−6 mm3/(N.m). The lowest wear coefficient below 10−6 mm3/(N.m) with water lubrication was found for Si3N4-TiN and S-RBSi3N4; water reduces the variability in wear coefficient for Si3N4- and SiC-based ceramics. 相似文献
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Three sets of tests were conducted using a pin-on-disk tribometer to determine the tribological behavior of ceramics at high sliding speeds in steam. In the first set, the speed was increased from 4000rpm to 10,000rpm in 1000 rpm increments. Constant rotational speeds of 4000rpm, 6000rpm, 8000 rpm and 10,000 rpm were used in the second test series. In the third series of tests, the rotational speed was slowly increased to 10,000rpm and allowed to coast down to zero. While the coefficient of friction for silicon nitride/YTZP pair varied between 0.2 and 0.4 without a clear pattern as the speed was increased in the first two test series, it decreased from about 0.6 to 0.2 when the speed was raised to 10,000 rpm in the third test series. This behavior is attributed to the general phenomena of powder lubrication as the wear debris provides an interfacial layer leading to reduced friction at high speeds. The coefficient of friction for silicon nitride/silicon carbide pair was substantially reduced to about 0.02 as the speed was raised. The low coefficient of friction, however, increased to a high level as the speed was further increased. The drop in friction is explained based on analysis of elasto-hydrodynamic lubrication assuming that a water film containing solid particles exists at the interface. Several possible mechanisms are suggested for the transition to a higher friction as the speed is raised: thermal effects at high flash temperatures, low residence times (for water adsorption on surface), collapse of the lubricant film and starvation effects. 相似文献
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Investigation on grinding temperature in ultrasonic vibration-assisted grinding of zirconia ceramics
The feasibility of ultrasonic vibration-assisted grinding (UVAG) in machining brittle materials, such as zirconia ceramics, has been preliminarily proved. The high temperature generated in grinding processes is a main factor responsible for thermal and surface/subsurface damage. However, there are few reports about grinding temperature for zirconia ceramics by UVAG. In this study, a grinding force model is used for the analysis of grinding temperature in UVAG based on kinematic principle of ultrasonic vibration and brittle material fracture removal mechanism. Then, the heat fluxes equation during grinding process is analyzed. And the grinding temperature model is developed based on theoretical grinding force model and heat fluxes. Finally, pilot experiments are carried out to analyze influence of vibration parameters and process parameters on UVAG temperature and verify the mathematical model. The comparison results show that ultrasonic vibration has an important influence on grinding temperature with the reduction of 10.6%. In addition, there is a good consistency between mathematical model and the experimental results. The average relative error is within 10%. Therefore, the mathematical model could be used to predict the UVAG temperature. 相似文献
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Advanced structural ceramics are presently used in several tribological applications such as precision instrument bearings, water pumps, automotive engine parts and cutting tools inserts. In the present work, the tribological behaviours of colloidally processed and pressureless sintered sialon ceramics with different phases ( and ) have been studied, aiming at increasing the industrial applications of sialon ceramics. The friction and wear behaviour of sialon ceramics against steel DIN-Ck45K were investigated using a pin-on-disk tribometer under dry conditions. Scanning electron microscopy (SEM), and energy dispersion spectroscopy (EDS) were used to analyse the worn surfaces of the sialon ceramics. Under the conditions used, sialon ceramics exhibited a typical mild wear (10-6 mm3 N-1 m-1) and the dominant wear mechanisms present were adhesive and abrasion. The results confirmed that colloidal processing and pressureless sintering are effective methods to prepare wear resistant sialon ceramic components. 相似文献
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Shinya Sasaki 《Lubrication Science》1999,12(1):67-78
Friction and wear tests were used to evaluate a partially stabilised zirconia (PSZ) disc rubbing against a PSZ pin in a high-vacuum sliding tester. The surrounding atmosphere contained an organic compound vapour (either benzene, acetone, methane or methanol) at a reduced pressure. In order to understand the mechanism of the tribochemical reaction, the sliding conditions, velocity, and load were varied. During the sliding test, the friction coefficient, surface electrostatic voltage, and adsorption behaviour were measured dynamically. After the sliding test, the worn surfaces were analysed with EPMA and TOF-SIMS to characterise the components and the molecular weight of the reaction products. The formation of sticky reaction products was observed on the sliding surface in benzene and acetone vapours. These products acted as lubricants, reducing the friction coefficients and wear rates. Analysis suggested that such sticky reaction products contained molecules up to 1000 atomic mass units (AMU). 相似文献
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The aim of this paper is to illustrate the similarities and variations between friction and wear data acquired with two different types of laboratory tribological test equipment that not only operate in the gap between macro‐ and nano‐testing, but also provide test parameters that allow an overlap across the whole scale from macro‐ to nanoscale friction and wear tests. Comparative wear tests were conducted under identical test conditions in the overlap region between macro‐ and micro‐regions using an existing piece of laboratory fretting test equipment and a novel one. The experimental test data obtained with these two experimental set‐ups are discussed. 相似文献
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Chenghe Wang 《Lubrication Science》1994,11(1):45-51
With the widening use of plastics, it has become an urgent task to study their behaviour in friction systems. The present paper reviews the applications of plastics during the past decades and their function in friction systems. The paper analyses the basic differences between metals and plastics in structure and properties, and points out the limitations, or inapplicability, of using metal tribology to solve problems in plastic friction systems when even different kinds of high-molecular materials have different shapes and applications. The paper also looks at the variety of plastic surfaces, and briefly presents the mechanism, theory, and calculation of the fiction, wear, and lubrication of plastics; theories of plastic wear are summarised. Also presented are the technical functions, simple application techniques, and economic benefits of plastic friction systems. 相似文献
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On the influence of test parameters on friction and wear of ceramics in oscillating sliding contacts
Dieter Klaffke 《Lubrication Science》1995,1(4):311-320
The tribological behaviour of different ceramics in contact with steel was studied for the case of oscillating sliding motion with a ball-on-disc apparatus. The influence of several test condition parameters was investigated by a systematic variation of the stroke, frequency, and normal load at room temperature in laboratory air at different levels of relative humidity. Each of the four parameters was varied in three stages. While the coefficient of friction was only mildly influenced by the operational variables, the coefficient of wear showed great variations and depended strongly on the humidity of the surrounding air. The effect of the operational variables and of the humidity on friction and wear varied for the different materials under investigation. 相似文献
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Many ceramics wear by more than a single wear mechanism. To understand how different wear mechanisms contribute to the wear properties of ceramics, quantitative measures of those mechanisms are required. Surface slope distribution analysis was investigated as a method of quantitatively analysing wear mechanism signatures, based on a simple model of the variation of slope with wear mechanism. Slope distribution was shown to be similar for materials within the same class of ceramics, e.g. silicon carbides. However, the range of slope parameters for a mechanism overlapped with that of other mechanisms, so that a mechanism was not found to yield a unique combination of slope parameters. A comparison of wear rate and slope distribution showed that wear could be correlated with specific sections of the distribution, and that this correlation was dependent upon the ‘dominant’ wear mechanism. Secondary effects on the slope distribution, e.g. porosity, invalidated the data for that material for use in slope analysis. 相似文献
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Two formulas were derived earlier using the theory of wear of I.V. Kraguelskii to calculate the wear resistance of friction pairs. To use them it was necessary to determine the friction contact fatigue parameters. The present paper deals with the method of experimental calculated assessment of these parameters and the results of its validation using wear resistant nanostructured alloyed zirconium dioxide crystals and engineering ceramics. 相似文献
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V. G. Novytskyy 《Lubrication Science》2004,10(3):265-274
Under sliding friction, nickel (0.3–4.2 wt.%) alloyed with chromium steel (1.2 wt.% carbon; 15 wt.% chromium) exerts a fundamental influence upon the initial structure of the steel and the phase composition and structure of the near‐surface friction layers. The minimum wear of the steel occurs when there is a dynamic equilibrium between the dislocation densities in the α‐ and γ‐phases and a ratio between the γ‐ and α‐phases of 50:50 for steels after quenching and 25:75 for steels after tempering in the near‐surface friction layers. 相似文献
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This paper describes tests carried out on a tribometer functioning at high temperature and equipped to record continuously the various test parameters, namely, the normal applied load, the tangential friction force, the differential movement of the contact surfaces, and the temperature of the sample. Dry friction tests, conducted on two aluminas of different purities, showed different degradation regimes at both 20 and 800°C. Thus, three successive periods of functioning were identified and correlated with transitions in the mechanism of degradation of the surfaces or in the mechanism of interfacial adaptation in the contact. The first period corresponds basically to the adaptation mechanisms of the interfaces with no wear material generated. The two subsequent periods demonstrate the degradation mechanisms of the surfaces leading to the production of more or less wear material and resulting in different states of equilibrium between production, recirculation, and loss of wear debris through the contact. 相似文献