Ingenieurwissenschaften und zugeordnete Tätigkeiten
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- 2018 (19) (entfernen)
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- Zeitschriftenartikel (19) (entfernen)
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- Friction (6)
- Niobium carbide (6)
- Wear (6)
- Cermet (4)
- Mechanical properties (3)
- Sintering (3)
- Alumina (2)
- Hardness (2)
- NbC (2)
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Organisationseinheit der BAM
- 9.5 Tribologie und Verschleißschutz (19) (entfernen)
In the present work it was shown that the addition of VC or a combination of VC + Ti(C0.7N0.3) was efficient in reducing the NbC grain growth during liquid phase sintering, when compared to NbC-Ni equivalents. A finest NbC grain size of 1.48 µm was obtained in the NbC-15 Ti(C0.7N0.3)-10 Ni-7.5 VC cermet, exhibiting a hardness of 1486 +/- 7 kg/mm2 and a fracture toughness of 8.7 +/- 0.1 MPa m 1/2.
Commercial grade-1 titanium samples (Ti, 99.6%) were treated using three alternative methods, (i) femtosecond laser processing, (ii) thermal heat treatment, and (iii) electrochemical anodization, respectively, resulting in the formation of differently conditioned superficial titanium oxide layers. The laser processing (i) was carried out by a Ti:sapphire laser (pulse duration 30 fs, central wavelength 790 nm, pulse repetition rate 1 kHz) in a regime of generating laser-induced periodic surface structures (LIPSS). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning setup for the processing of several square-millimeters large surface areas covered homogeneously by these nanostructures. The differently oxidized titanium surfaces were characterized by optical microscopy, micro Raman spectroscopy, variable angle spectroscopic ellipsometry, and instrumented indentation testing. The tribological performance was characterized in the regime of mixed friction by reciprocating sliding tests against a sphere of hardened steel in fully formulated engine oil as lubricant. The specific tribological performance of the differently treated surfaces is discussed with respect to possible physical and chemical mechanisms.
In the present work an approach is presented which combines various aspects of the former models with probability considerations. It is used to simulate the impact of more than one billion Alumina particles onto a steel substrate. This approach permits the simulation of an entire erosion experiment on an average PC within about six hours.
The effects of weathering exposure on unfilled and filled thermoplastic polyurethanes (TPU) materials are described as performed under different humidity conditions. For this purpose, a weathering device was used with UV-A 340 nm lamps at a constant temperature of 40 °C. The effects of environmental (UV and humidity condition) degradation on the frictional properties of TPU materials are presented along with surface analyses to characterize the chemistry of the degradative process. Photooxidative degradation of unfilled polymer leads to deterioration of physical and mechanical properties, which affects its tribological behavior significantly. Due to crosslinking, the stiffness of the material increases, reducing drastically the friction coefficient of unfilled TPUs. The frictional behavior of glass fiber reinforced TPU is less affected by radiation.
Niobcarbid (NbC) stellt aufgrund vorteilhafter Eigenschaften, wie zum Beispiel eine geringe Diffusionsneigung, in der Zerspannung eine vielversprechende Alternative zu konventionellen Schneidstoffen wie Wolframcarbid (WC) dar. Als Substitution der Hartstoff-Phase WC im Hartmetall wird NbC in der trockenen Drehbearbeitung von eisen-basierten Werkstoffen untersucht. Diesbezüglich wurden zwei NbC-Substrate mit WC hinsichtlich ihres Werkzeugverschleißes quantitativ verglichen. Im Gegensatz zu WC-Werkzeugen wird das Potential von NbC bei zunehmender Schnittgeschwindigkeit vc durch eine steigende Prozessstabilität deutlich.
Research and development of WC grades is 90 years ahead of niobium carbide-based hard materials, which showed already as light-weight and unexplored material a very high potential for many technical applications, especially for wear protection and machining. NbC evoluted recently from lab scale to pilot scale, especially in areas where established WC-based materials are causing economic, environmental or technical concerns. Benchmark trials of NbC-based hard metals indicated already a favorable performance in machining of steel components.