Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (62)
- Vortrag (48)
- Beitrag zu einem Tagungsband (33)
- Beitrag zu einem Sammelband (20)
- Posterpräsentation (2)
- Forschungsbericht (2)
- Buchkapitel (1)
- Sonstiges (1)
Schlagworte
- Wear (21)
- Friction (16)
- Temperature (12)
- Fretting (9)
- Silicon carbide (7)
- Ceramics (6)
- Reibung (6)
- Alumina (4)
- Ceramic (4)
- Humidity (4)
- Oscillating sliding (4)
- Relative humidity (4)
- Titanium carbide (4)
- Contact pressure (3)
- DLC (3)
- Dispergierung (3)
- Dry sliding (3)
- Hardness (3)
- Hot steam (3)
- Lubricated sliding (3)
- Microstructure (3)
- Nanopulver (3)
- Niobium carbide (3)
- Roughness (3)
- Schwingungsverschleiß (3)
- Silicon nitride (3)
- Simulation (3)
- TiC (3)
- Titanium diboride (3)
- Tribofilm (3)
- Tribologie (3)
- Wires (3)
- Abrasion (2)
- Activation energy (2)
- Atomic force microscopy (2)
- Bearbeitbarkeit (2)
- Beschichtung (2)
- Ceramic composites (2)
- Coating (2)
- Colloidal processing (2)
- Composites (2)
- Dentalkeramik (2)
- Diamond like carbon (2)
- EDS (2)
- Folie (2)
- HIP-Simulation (2)
- High temperature (2)
- Keramik (2)
- Lubrication (2)
- Movable cellular automata (MCA) (2)
- Partial slip (2)
- Polyetherimide (2)
- Polymers (2)
- Reciprocating sliding (2)
- SiC (2)
- Sliding speed (2)
- Steel (2)
- Stick-slip (2)
- Surface temperature (2)
- TiB2 (2)
- Titanium boride (2)
- Tribology (2)
- Verbundwerkstoffe (2)
- Verschleiß (2)
- Wear mechanism (2)
- Wear particles (2)
- Zirconia (2)
- A-C:H (1)
- AFM (1)
- Abrasive wear (1)
- Abriebverhalten (1)
- Alcaline earth fluorides (1)
- Alpha-alumina (1)
- Alumina powder (1)
- Aluminium oxide (1)
- Apha-alumina (1)
- Artificial hip joint (1)
- Ball-on-disk (1)
- Bearing steel (1)
- Bending strenght (1)
- Bending strength (1)
- Binder (1)
- Biopolymers (1)
- Boundary lubrication (1)
- CNx Schichten (1)
- COF (1)
- Ca-Ba fluoride (1)
- Calculation of wear volume (1)
- Carbon nanofiber (1)
- Carbon nitride (1)
- Cast iron (1)
- Ceramic Composites (1)
- Ceramic powders (1)
- Ceramic wear (1)
- Cermet (1)
- Cermets (1)
- Coating failure (1)
- Coefficient of friction (1)
- Colloid vibration current (CVI) (1)
- Composite (1)
- Composits (1)
- Computertomography (1)
- Contact geometry (1)
- Contact geometry crossed cylinders (1)
- Contact mechanics (1)
- Correlation of measurement (1)
- Counter body material (1)
- Counterbody (1)
- Counterbody influence (1)
- Crossing angle (1)
- Deairing (1)
- Defect type (1)
- Dental ceramic (1)
- Dental materials (1)
- Diaspore (1)
- Dispergieren (1)
- Dry oscillating sliding (1)
- Dry-slidins (1)
- EPMA (1)
- Electron probe microanalysis (1)
- Elemental mapping (1)
- Energy dispersive X-ray spectroscopy (1)
- Explosive compaction (1)
- Femtosecond techniques (1)
- Festschmierstoff (1)
- Fibers (1)
- Foliengiessen (1)
- Fretting corrosion (1)
- Fretting fatigue (1)
- Fretting regime (1)
- Fretting regimes (1)
- Fretting test (1)
- Fretting wear (1)
- Gas pressure sintering (1)
- Gelcasting (1)
- Graphene oxide (1)
- Graphit (1)
- Grease (1)
- Grease lubrication (1)
- Green compaction (1)
- Green state (1)
- Gross slip fretting (1)
- Grünkörper (1)
- Gümbel (1)
- Hard carbon coatings (1)
- High purity alumina (1)
- High temperatures (1)
- Hip simulator (1)
- Hirn (1)
- Hochleistungskeramik (1)
- Hohe Temperaturen (1)
- Humidity water (1)
- Imaging (1)
- Implantat (1)
- Infiltration (1)
- Interface (1)
- Isoelectric point (IEP) (1)
- Joining (1)
- Keramische Pulver (1)
- Kompositkeramik (1)
- Kontaktmechanik (1)
- Life science (1)
- Light elements (1)
- Liquid media (1)
- Low IR-emission ceramics (1)
- Low pressure injection molding (1)
- Lubricant additives (1)
- Lubricants (1)
- Lubricated contact (1)
- Luftfeuchte (1)
- Machinability (1)
- Magnetronsputtern (1)
- Martens (1)
- Mating material (1)
- Meßverfahren (1)
- Micro positioning (1)
- Mixed fretting regime (1)
- Modellierung (1)
- Modellsystem (1)
- Modellverschleißprüfung (1)
- Nano scale (1)
- Nanoadditive (1)
- Nanocrystalline powder (1)
- Nanopartikel (1)
- Nanoscale EDX analysis (1)
- Nanoscale T-SEM (1)
- Nanosecond techniques (1)
- NbC (1)
- Nckel binder (1)
- Ni (1)
- Niobium carbide (NbC) (1)
- Null-Verschleiß (1)
- Oscillation sliding (1)
- PAEKs (1)
- PEI (1)
- PVD coatings (1)
- Paraffin oil (1)
- Particle (1)
- Particle charge detection (PCD) (1)
- Particle size (1)
- Particulate composite (1)
- Particulate composites (1)
- Performance test (1)
- Phase analysis (1)
- Piezoelectric actuator (1)
- Plastic deformation (1)
- Polyetherketone composite (1)
- Polyethylene (1)
- Polymer (1)
- Porous zirconia (1)
- Preceramic polymer (1)
- Pressureless sintering (1)
- Properties (1)
- Raman spectra/condensed matter (1)
- Raman spectroscopy (1)
- Randzone (1)
- Rauhigkeit (1)
- Reciprocating sliding test (1)
- Reciprocating sliding wear (1)
- Reibungsverhalten (1)
- Reversierender Gleitverschleiß (1)
- Running in (1)
- SEM (1)
- Shaping methods (1)
- Siliconcarbonitride (1)
- Siliziumkarbid (1)
- Sintering (1)
- Sintern (1)
- Solid content (1)
- Solid lubricant (1)
- Solid lubricants (1)
- Solid lubrication (1)
- Spectrum imaging (1)
- Stahl (1)
- Standardisierung (1)
- Steam (1)
- Stick slip (1)
- Stitching technique (1)
- Streaming potential (1)
- Stribeck (1)
- Stribeck curve (1)
- Surface roughness (1)
- Surface topography (1)
- Suspensionen (1)
- Synergieeffekte (1)
- TSEM (1)
- Test bed (1)
- Thermochemische Analyse (1)
- Thurston (1)
- Titan (1)
- Titanium nitride (1)
- Transferschmierung (1)
- Tribo-film (1)
- Tribo-oxidation (1)
- Tribochemistry (1)
- Tribooxidation (1)
- UHMWPE (1)
- Unlubricated tests (1)
- Verschleißberechnung (1)
- Verschleißfestigkeit (1)
- Verschleißmodelle (1)
- Verschleißpartikel-Analyse (1)
- Viscosity (1)
- Water lubrication (1)
- Wear infiltration (1)
- Wear mechanisms (1)
- Wear particle analysis (1)
- Wear quantities (1)
- Wear resistance (1)
- Wear scar (1)
- Wear volume (1)
- Werkstoffentwicklung (1)
- White light interferometry (1)
- XPS/surface analysis (1)
- Yttrium titanate (1)
- Zero-wear (1)
- Zeta Potenzial (1)
- Zeta potential (1)
- Zirconium titanate (1)
- Zwischenmedium (1)
- a-C:H (1)
- gebundene Filme (1)
- pH-Wert (1)
- pH-value (1)
- ta-C (1)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (48)
The tribological performance of a hydrogenated amorphous carbon coating on Ti6Al4V against ceramic balls was checked by simple reciprocating sliding tests and by more complicated tests in a hip joint simulator. 3 of 4 joints failed during hip simulator testing already after approximately 100 × 10³ cycles and possibly due to coating failures caused by insufficient polishing of the metallic acetabular cups prior to coating deposition. Since such failures occurred only occasionally, the problem was not revealed by reciprocating sliding tests which are stressing a much smaller surface area compared to the tests in the hip joint simulator. Another type of failure, pits of 12 µm in diameter distributed randomly at the coating surface, was frequently observed by Scanning Electron Microscopy and analyzed comprehensively by Focused Ion Beam technique in combination with Transmission Electron Microscopy in one case. Although not necessarily affecting wear, such small failures might cause long-term problems in vivo, by providing access of body fluid to the substratecoating interface making it susceptible to corrosion.
The tribological behaviour of different monolithic and composite ceramics was evaluated in the temperature range between room temperature and 750°C. The test method was oscillating sliding with a ball-on-disk arrangement in an SRV machine. Alumina balls were used as counter body. The friction behaviour was determined on-line, and the wear behaviour was determined from calculations on the basis of wear scar dimensions and profilometric measurements. The friction depends on temperature and shows an increase for most materials for increasing temperature; the smallest friction at all temperatures is found for monolithic TiC. The wear behaviour shows different trends for the different materials. In tests against SiC a maximum of wear is found at 500°C, for TiC at 200°C and for TiB2 at 750°C. The composite ceramics suffer the smallest wear of all materials in the range from 200°C to 500°C.
The tribological behaviour under dry sliding conditions of Magneli phase Ti4O7 and e-phase Ti2Cr2O7 with α-alumina as a sliding partner has been characterised at room temperature by oscillating sliding. The mechanical properties as well as Vickers hardness measurements do not reveal big differences between the materials, and 4-point bending strengths are around 200 MPa for both materials. Although the friction coefficients are in the medium range of 0.6 and do not differ much between the materials, the wear behaviour is very different. At room temperature, the wear coefficient of Ti2O7 is strongly dependent on relative humidity, and wear is highest under dry conditions when relative humidity is low as it is typically found for many ceramic materials. Ti2Cr2O7 shows remarkably different wear behaviour with the lowest wear in dry conditions. The measured coefficients of wear at low relative humidity of 4% are more than 2 orders of magnitude lower than those for Ti2O7.
Stribeck curve
(2014)
The importance of lubricants in virtually all fields of the engineering industry is reflected by an increasing scientific research of the basic principles. Energy efficiency and material saving are just two core objectives of the employment of high-tech lubricants. The encyclopedia presents a comprehensive overview of the current state of knowledge in the realm of lubrication. All the aspects of fundamental data, underlying concepts and use cases, as well as theoretical research and last but not least terminology are covered in hundreds of essays and definitions, authored by experts in their respective fields, from industry and academic institutes.
COMPOSITE MATERIALS OF A 99.7 % ALPHA-ALUMINA MATRIX WITH PLATELETS OF SILICON CARBIDE (SICP) HAVE BEEN PREPARED BY GELCASTING. DENSIFICATION WAS CARRIED OUT BY GAS-PRESSURE SINTERING WITHOUT FURTHER SINTERING AIDS. FIVE DIFFERENT COMPOSITIONS WITH 0, 5, 10, 15, AND 20 VOL.% SICP RESP. HAVE BEEN INVESTIGATED AND TRIBOLOGICAL PROPERTIES WERE CHARACTERIZED. INCREASING AMOUNT OF SICP AS RIGID PARTICLES IN THE FINE GRAINED MATRIX COMPLICATE THE DENSIFICATION PROCESS. WITH THE APPLICATION OF 50 BAR AR PRESSURE DURING THE FINAL SINTERING STEP AT A TEMPERATURE OF 1700 DEGREE C THE DENSITY OF THE SAMPLES COULD BE INCREASED BY 3-5%. INVESTIGATION OF THE TRIBOLOGICAL PROPERTIES AGAINST STEEL AS A COUNTERBODY UNDER UNLUBRICATED OSCILLATING SLIDING CONDITIONS SHOWED A HIGH COEFFICIENT OF FRICTION AND AN INCREASING WEAR RATE UP TO A SICP CONTENT OF 10 VOL. % . AT 15 AND 20 VOL. % SICP RESP. BOTH THE COEFFICIENT OF FRICTION AND THE COEFFICIENT OF WEAR DROP DOWN.
Influence of Slip Viscosity on the Mechanical Properties of High Purity Alumina made by Gelcasting
(1997)
The tribological behavior of different low infrared (IR) emission ceramic materials from the titanate group has been investigated at room temperature under gross slip fretting conditions against 100Cr6 ball bearing steel and α-alumina as the counterface materials. For all material pairs, friction and wear depended largely on the relative humidity of the environment. When paired with steel the low IR-emission ceramic disks showed higher wear resistance. Under dry conditions, almost no wear was found on the low IR-emission ceramic specimen. The high wear on the steel counter body is caused not only by tribo-oxidation, which is the main wear mechanism, but also by abrasion. In dry conditions a COF of 0.6 and in humid conditions a COF of 0.2 have been measured. When paired with α-alumina the results on wear are just opposite to those with steel counterbody and the low IR-emission ceramic materials show much lower wear resistance under all conditions. This is explained by the predominance of abrasion and the relatively large difference in hardness between the low IR-emission ceramic and α-alumina. In high humidity environments the results point to the formation of stable reaction layers causing lower friction and wear.
Self-mated magnesia stabilized zirconia (Mg-PSZ) ceramic sliding couples have been investigated at 100 N load (P0max= 1324 MPa) in oscillating sliding conditions in different humidity conditions in air and in hot steam. Temperatures have been varied up to 400 °C and pressures up to 6 bars. The results show that the wear behavior of MgO-ZrO2 under high Hertzian contact pressures is strongly dependent on temperature and is similar for both dry oscillating and oscillating in hot steam. However, although the evolution in wear rates on temperature is similar and the wear rates of MgO-ZrO2 plunged above 300 °C in hot steam and air by nearly three orders of magnitude, SEM micrographs revealed in hot steam at 400 °C smooth wear tracks. In contrast, hot steam enhanced the tribochemistry of self-mated alumina couples and reduced wear rates. Hot steam decreased the coefficients of friction of MgO-ZrO2 with increasing temperature, but not the wear rates.
It has been successfully demonstrated that ceramic materials can be joined in the green
state without a second phase by using low pressure injection molded parts. The investigation of the
joining interface revealed that a high quality interface can be achieved by carefully adjusting the
different manufacturing steps. The use of monomodal particle size distribution in the used powder
CT3000SG is inferior to a broader particle size distribution obtained by replacing 33% of the finer
alumina powder by coarser CT1200SG. In this way the dewaxing process is significantly improved
when the wall thickness of the part exceeds 3 mm. The investigation of the mechanical properties of
the joined and sintered parts revealed, that the bending strength of the joined specimens achieved
about 80 % of the unjoined, monolithic specimens.
Zeta potential as measured with the electrokinetic sonic amplitude (ESA) method has been compared to streaming potential as measured with the particle charge detection (PCD) method. The measurements have been carried out on identical suspensions of a-Al2O3, SiC and Si3N4 with a solids volume fraction of 1% and 10%. Zeta potential and streaming potential are related by a linear function. The correlation coefficients for this relationship are better than 0.99 for the suspensions with 1% solids loading. For the suspensions with 10% solids loading, correlation coefficients are slightly lower due to the influence of increasing viscosity. Regardless of lower correlation at the higher solids loading, the isoelectric pH is constant within the limits of accuracy of the pH measurements.
Es wird die Untersuchung des Entlüftungsvorgangs in Keramikschlickern beschrieben, die Teil des Gelcastingprozesses zur Herstellung hochfester Aluminiumoxidkeramiken sind. Ziel der Untersuchung war es, den Einfluss von Viskosität und Entlüftungszeit als prozessvariablen auf die Entstehung von bruchauslösenden Fehlern im Gefüge zu verdeutlichen.
With respect to their excellent material properties ceramics are of interest as candidate materials for tribological applications. The friction and wear behaviour of ceramics is often superior to that of metallic materials. Furthermore, an essential improvement of tribological performance will be possible by tailoring of ceramics in the process of powder preparation and sintering technique. Silicon Carbide (SiC) shows interesting friction and wear behaviour at room temperature, even under unlubricated running conditions but is very sensitive against effects of environmental humidity and shows high friction and high wear in the absence of water vapour. The tribological performance of SiC can be improved considerably by adding substantial amounts of TiC and TiB2 to the microstructure thus creating ceramic particulate composite materials.
Various composites in the quasi ternary system SiC-TiC-TiB2 were prepared by a ceramic manufacturing process including sintering temperatures up to 2180 °C. Comparative tribo tests were performed under unlubricated oscillating sliding motion in dry, normal, and moist air and under water lubrication with SiC balls and Al2O3 balls as counter bodies. The friction is affected by the relative humidity (RH) but barely at all by the composition of the composites. The wear resistance of the composites was found to be improved considerably by addition of TiB2 in the range from 20 to 60 %. The highest wear resistance of the system wear was found when Al2O3 was used as counter body material.
The friction and wear behaviour of SiC, Si3N4 and SiC/Si3N4 composite ceramics were investigated with oscillating sliding (gross slip fretting) at room temperature. The influence of counter body material and the humidity of the surrounding air was studied with a ball-on-disc configuration with different ball materials (1000Cr6, Al2O3 SiC and Si3N4). The effect of RH on friction is marginal with exception of SiC (low friction) as counter body material. The wear behaviour, however, is strongly affected by humidity, showing inverse trends for different counter body materials. Consequently, the wear behaviour of a tribo couple can be improved by selecting an adequate mating material. The results reveal the necessity to control RH in tribological tests. For estimation of the performance of tribo couples under varying environmental conditions, a variation of RH is required. In tribo couples with single phase SiC, either as ball or disc, the tribological behaviour of the system is dominated by SiC. The friction behaviour of the composite material is in between the behaviour of the two single phase materials, Si3N4 and SiC, whereas the wear behaviour is very similar to that of single phase Si3N4.
The friction and wear behaviour of a new developed, pressureless sintered TiB2 ceramic was studied in comparison to SiC against SiC and Al2O3 balls under unlubricated conditions at room temperature. Special attention was paid to the influence of relative humidity on friction and wear results. For both ceramics the coefficient of friction against both ball materials decreases with increasing humidity and is higher in tests against alumina than against SiC. The wear rate is affected significantly by humidity and decreases by one order of magnitude for Al2O3/SiC system and by 2 orders of magnitude for SiC/SiC system. For TiB2 wear rates are nearly not affected by humidity against both ball materials and are much smaller than for SiC.
Ceramics are of increasing interest for application in many branches of technique. In order to improve the tribological performance of ceramic materials, composites on the basis of silicon carbide with different amounts of titanium carbide, boron carbide, titanium diboride and free carbon in the form of graphite were manufactured by a reaction sintering process.
The friction and wear behaviour of these composites was investigated with oscillating sliding motion in unlubricated tests at room temperature on different levels of relative humidity. Additional tests were performed under water lubrication, revealing the superior behaviour of composites for special test conditions. A major influence of the free carbon on friction or wear behaviour was not observed. The tribological behaviour in air as well as under water is mainly dependant on the amount of titanium phases.
Ceramic particulate composites in the system SiC-TiC-TiB2 sliding against SiC and Al2O3 under water
(1999)
The tribological behaviour of SiC, SiC-TiC and SiC-TiC-TiB2 was determined in oscillating sliding against SiC and -Al2O3 in water at room temperature. The tribo-systems with the composite materials containing TiC and TiB2 differ significantly from the systems with the single phase SiC: The wear is reduced and the friction is increased. The wear reduction up to a factor of 10 is mainly due to the formation of an oxide film containing titanium oxides which is soft, stable in water and well adhering to the bulk material. This oxide film is transferred to the alumina ball but not to the silicon carbide ball.
The high temperature tribological performance of tetrahedral amorphous carbon coatings has been analyzed at elevated temperatures up to 250 °C in air against three different counterbody materials-steel 100Cr6, a-alumina and silicon nitride. The results show that the counterbody material influences the friction and wear behavior and therefore coating life time strongly. This effect is well known for these coatings at room temperature under dry environmental conditions, equivalent to conditions above 100 °C when water molecules desorb from the surface. However, the sharp difference in tribological performance between silicon nitride on the one hand and alumina and steel on the other hand cannot be understood in this context. Analyzing the friction behavior during the running-in phase, it is evident that only alumina and steel form a stable interface with constant low friction and relatively low wear rates. Silicon nitride forms an unstable interface with fluctuating COF and relatively high wear rates due to its own inherent tendency to tribo-oxidation.
An extended study on tribological properties of carbon nitride coatings under oscillating sliding conditions has been carried out. The coatings were prepared by reactive magnetron sputtering with graphite target using nitrogen as reactive gas in an argon/nitrogen atmosphere during the deposition process to deposit carbon nitride, CNx. Coating thickness was about 2 µm. A 200300 nm thick Ti interlayer was used to enhance adhesion. The nitrogen flow during the deposition was varied to control the amount of nitrogen in the coating. Maximum amount of N-content was about 28 at%, achieved at a maximum N2 flow rate. Other deposition parameters were target to substrate distance, substrate temperature during deposition and bias voltage. The results show a large variation of hardness depending mainly on the nitrogen content and bias voltage. Higher bias voltage produced harder coatings as did lower nitrogen content. The tribological properties were tested unlubricated and lubricated by paraffin oil under gross slip fretting conditions at room temperature against alumina as counter material. Most coatings, but not all, showed a more or less pronounced dependence of wear on relative humidity with wear rates from 10-5 to 10-6 mm3/Nm. The best coatings with regard to a low wear rate and the least dependence upon relative humidity were carbon nitride coatings deposited at elevated substrate temperatures up to 350 °C. The wear resistance of these coatings was increased under the most severe conditions by about one order of magnitude. The results are discussed on the basis of a transfer layer formation. The results show clearly that wear is not significantly correlated to the coating hardness which itself is strongly dependant on the nitrogen content. However, under lubricated conditions with paraffin oil, wear rates were generally very low with wear coefficients at about 10-8 mm3/Nm.
A new method for sampling wear particles directly from the lubricant reservoir has been developed and applied successfully for analyzing wear particles by high-resolution scanning electron microscopy in transmission mode having coupled energy-dispersive X-ray spectroscopy. The lubricated tribological testing was carried out with fully formulated as well as with non-formulated synthetic base oil. It was possible to analyze individual particles with dimensions as small as about 5–30 nm which are likely the 'primary' wear particles. A majority of the particles, however, are agglomerated and, thus, lead to the formation of larger agglomerates of up to a few micrometers. Chemical analysis led to the conclusion that most of the observed particles generated in formulated oil, especially the larger ones, are composed of the additives of the lubricant oil. In non-formulated base oil, the primary particles are of similar dimensions but contain only iron, chromium and oxygen, but most likely stem from the mating materials. This finding points to the fact that the main wear mechanism under lubricated conditions with fully formulated oil is more like a continuous shearing process rather than a catastrophic failure with the generation of larger primary particles. When the oil is non-formulated, however, several wear mechanisms act simultaneously and the wear rate is increased significantly. Generated larger primary particles are milled down to the nanoscale. When the oil is fully formulated, wear mainly takes places at the additive layer or tribofilm; thus, the steel surface is protected.
The influence of temperature and counterbody material on the tribological properties of a-C:H
coatings deposited on Cronidur 30 steel has been investigated in a lubricated ball on disk
contact situation with alpha-alumina and silicon nitride as counterbodies. The results show, that the wear volumes of the systems increase exponentially with increasing temperature, for alpha-alumina more than for silicon nitride. Two different wear mechanisms seem to have a
major influence: First, the abrasive action due to materials hardness and second, the tribo-oxidation when silicon nitride is counter material.
The influence of temperature and counterbody material on the tribological properties of a-C:H coatings deposited on Cronidur 30 steel has been investigated in a lubricated ball on disk contact situation. The results show, that the wear volumes of the system increase exponentially with increasing temperature. Two different wear mechanisms seem to have a major influence: First, the abrasive action due to materials hardness and second, the tribooxidation when silicon nitride is counter material.
In this article we demonstrate the use of atomic force microscopy (AFM) measurements for the study of macroscopic wear scars. By stitching AFM images acquired over the wear scar, the detailed structure of the scar can be characterized even when the scar is much wider than the typical maximum scan range of the AFM (50–100 µm). The results obtained by AFM are compared with those yielded by white light interferometry (WLI). The comparison validates the WLI measurements; at the same time, it shows decisive differences in the resolutions of these two methods. As a consequence, AFM measurements are necessary whenever a precise characterization of the structure of the scar is required. However, since stitching of AFM images is rather time-consuming, white light interferometry is recommended as a faster method whenever experiments are aimed at just a gross characterization of the scar and the measurement of mean quantities (e.g. the wear volume).
Fretting
(2014)
The importance of lubricants in virtually all fields of the engineering industry is reflected by an increasing scientific research of the basic principles. Energy efficiency and material saving are just two core objectives of the employment of high-tech lubricants. The encyclopedia presents a comprehensive overview of the current state of knowledge in the realm of lubrication. All the aspects of fundamental data, underlying concepts and use cases, as well as theoretical research and last but not least terminology are covered in hundreds of essays and definitions, authored by experts in their respective fields, from industry and academic institutes.
Three different contact geometries, ball on disk and two different settings with crossed cylinders have been investigated with regard to the agreement of the results of the tribological quantities determined by each method. The material combination was α-alumina as upper specimen and steel 100Cr6 as lower specimen. For each of the contact geometries 5 independent measurements were carried out and evaluated independently. The agreement between the single results of coefficient of friction and the coefficient of system wear as well as between the different groups and conditions are good. Largest scatter of the results were found in the dry air regime where both friction and wear depend strongly on the relative humidity. However, comparison of the absolute values of the coefficient of wear between the ball on disk contact geometry on one side and the 2 crossed cylinder contact geometries on the other side reveals a significant difference in that the ball on disk results are lower by about a factor of two. The results document also a high degree of repeatability of single wear tests.
Die für einen erfolgreichen Einsatz von Festschmierstoffen zur Minderung von Reibung und Verschleiß systembestimmender Parameter wie Last, Geschwindigkeit, Temperatur, umgebende Atmosphäre, Filmbildung und -haltung sowie die Anwendungstechnologien werden dargestellt, ferner Modellvorstellungen zum Verschleißverhalten von Festschmierstoffen im Hinblick auf konkrete Anwendungsfälle diskutiert.