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Friction Behavior (friction + behavior)
Selected AbstractsFriction Behavior of Dental Porcelain with Different Leucite Particle SizesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2008Yi Zhang The effect of leucite particle size on the friction behavior of dental ceramics was investigated using a ball-on-disc tribometer. The experimental loads were 20, 30 and 40 N and the tests were conducted unlubricated and under the lubrication of an artificial-saliva. Dental ceramics with different leucite particle sizes, i.e. 0.5±0.2, 1.2±0.3 and 5±2 ,m, were prepared by sintering the mixture of a low temperature frit and leucite powders with different average particle sizes (0.4, 1 and 5 ,m). The results showed that the leucite particle size, experimental load and lubrication media had not significant effects on the steady-state friction coefficient of the samples. However, the evolution of the friction coefficient was different, which could be generally classified into two categories, i.e. with and without an abrupt increase in the friction curve. The changes in experimental condition and leucite particle size were attributed to such difference. [source] Investigation of the sliding behavior between steel and mortar for seismic applications in structuresEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 12 2009Jason McCormick Abstract The friction developed between a steel base plate and a mortar base contributes shear resistance to the building system during a seismic event. In order to investigate the possible sliding behavior between the base plate and the mortar, a shake table study is undertaken using a large rigid mass supported by steel contact elements which rest on mortar surfaces connected to the shake table. Horizontal input accelerations are considered at various magnitudes and frequencies. The results provide a constant friction coefficient during sliding with an average value of approximately 0.78. A theoretical formulation of the friction behavior is also undertaken. The theoretical equations show that the sliding behavior is dependent on the ratio of the friction force to the input force. The addition of vertical accelerations to the system further complicates the sliding behavior as a result of the varying normal force. This results in a variable friction resistance which is a function of the amplitude, phase, and frequency of the horizontal and vertical input motions. In general, this study showed a consistent and reliable sliding behavior between steel and mortar. Copyright © 2009 John Wiley & Sons, Ltd. [source] Tribology,Structure Relationships in Silicon Oxycarbide Thin FilmsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2010Joseph V. Ryan Silicon oxycarbide is a versatile material system that is attractive for many applications because of its ability to tune properties such as chemical compatibility, refractive index, electrical conductivity, and optical band gap through changes in composition. One particularly intriguing application lies in the production of biocompatible coatings with good mechanical properties. In this paper, we report on the wide range of mechanical and tribological property values exhibited by silicon oxycarbide thin films deposited by reactive radio frequency magnetron sputtering. Through a change in oxygen partial pressure in the sputtering plasma, the composition of the films was controlled to produce relatively pure SiO2, carbon-doped SiC, and compositions between these limits. Hardness values were 8,20 GPa over this range and the elastic modulus was measured to be between 60 and 220 GPa. We call attention to the fit of the mechanical data to a simple additive bond-mixture model for property prediction. Tribological parameters were measured using a ball-on-disk apparatus and the samples exhibited the same general trends for friction coefficient and wear rate. One film is shown to produce variable low friction behavior and low wear rate, which suggests a solid-state self-lubrication process because of heterogeneity on the nanometer scale. [source] Friction Behavior of Dental Porcelain with Different Leucite Particle SizesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2008Yi Zhang The effect of leucite particle size on the friction behavior of dental ceramics was investigated using a ball-on-disc tribometer. The experimental loads were 20, 30 and 40 N and the tests were conducted unlubricated and under the lubrication of an artificial-saliva. Dental ceramics with different leucite particle sizes, i.e. 0.5±0.2, 1.2±0.3 and 5±2 ,m, were prepared by sintering the mixture of a low temperature frit and leucite powders with different average particle sizes (0.4, 1 and 5 ,m). The results showed that the leucite particle size, experimental load and lubrication media had not significant effects on the steady-state friction coefficient of the samples. However, the evolution of the friction coefficient was different, which could be generally classified into two categories, i.e. with and without an abrupt increase in the friction curve. The changes in experimental condition and leucite particle size were attributed to such difference. [source] Processing and Tribological Properties of Si3N4/Carbon Short Fiber CompositesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2003Hideki Hyuga Si3N4/carbon fiber composites were fabricated using several types of fiber. All the composites had higher fracture toughness compared with monolithic Si3N4 ceramics. Tribological properties were investigated by a ball-on-disk method under unlubricated conditions. The composite containing fibers with a high orientation of graphite layers and high graphite content indicated a low friction coefficient. It was identified, by Raman spectroscopy, that graphite was transferred from the composite to the Si3N4 ball of the counterbody during the wear test. This transferred layer was effective for producing the low friction behavior of the composite. [source] Grain-Boundary Viscosity of Preoxidized and Nitrogen-Annealed Silicon CarbidesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2001Giuseppe Pezzotti Internal friction experiments were conducted on a model SiC polycrystal prepared from preoxidized (high-purity) SiC powder. This material contained high-purity SiO2 glass at grain boundaries in addition to a free-carbon phase, which was completely removed upon powder preoxidation. Comparative tests were conducted on a SiC polycrystal, obtained from the as-received SiC powder with the addition of 2.5 vol% of high-purity SiO2. This latter SiC material was also investigated after annealing at 1900°C for 3 h in a nitrogen atmosphere. Electron microscopy observations revealed a glass-wetted interface structure in SiC polycrystals prepared from both as-received and preoxidized powders. However, the former material also showed a large fraction of interfaces coated by turbostratic graphite. Upon high-temperature annealing in nitrogen, partial glass dewetting occurred, and voids were systematically observed at multigrain junctions. The actual presence of nitrogen could only be detected in a limited number of wetted interfaces. A common feature in the internal friction behavior of the preoxidized, SiO2 -added and nitrogen-annealed SiC was a relaxation peak that resulted from grain-boundary sliding. Frequency-shift analysis revealed markedly different characteristics for this peak: both the magnitude of the intergranular glass viscosity and the activation energy for grain-boundary viscous flow were much higher in the nitrogen-annealed material. Results of torsional creep tests were consistent with these findings, with nitrogen-annealed SiC being the most creep resistant among the tested materials. [source] | ||||||||||