scholarly journals Tribological properties of experimental hard alloys in conditions of friction on structural steel without lubricant

2018 ◽  
Vol 226 ◽  
pp. 01006
Author(s):  
Evgeniy V. Fominoff ◽  
Constantine G. Shuchev ◽  
Igor A. Khozyaev ◽  
Yuriy A. Tsarev ◽  
Viktor B. Rykov
Keyword(s):  
Tribological Properties ◽  
Base Alloy ◽  
Shielding Effect ◽  
Hard Alloys ◽  
Friction Forces ◽  
Friction Zone ◽  
High Entropy ◽  
Binding Phase ◽  
Welding Bridges

Tribological properties of the experimental grades of high entropy hard alloys with modified binding phase on cobalt, which are characterized by minimal value of absolute t.m.f. to carbide phase, were experimentally investigated. It was established experimentally that new grades obtain better friction characteristics in comparison with the base alloy grade VK8 because friction processes of these materials in contact with structural steels are characterized by lower friction forces and lower temperatures in the friction zones. The ‘third body’ which is thicker than for the base alloy grade VK8, obtains a positive gradient of mechanical properties in friction zone, has a shielding effect, reduces the rate of generation of adhesive joints (welding bridges), and, perhaps, performs the role of dry lubrication.

scholarly journals Influence of Aluminum and Molybdenum on the Microstructure and Corrosion Behavior of Thermally Sprayed High-Entropy Alloy Coatings

2021 ◽  
Author(s):  
Martin Löbel ◽  
Thomas Lindner ◽  
Maximilian Grimm ◽  
Lisa-Marie Rymer ◽  
Thomas Lampke
Keyword(s):  
Corrosion Resistance ◽  
Protective Coatings ◽  
Base Alloy ◽  
Alloy System ◽  
High Entropy Alloy ◽  
Oxide Content ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Structural And Functional Properties ◽  
Wide Range

AbstractHigh-entropy alloys (HEAs) have shown a wide range of promising structural and functional properties. By the application of coating technology, an economical exploitation can be achieved. The high wear and corrosion resistance of HEAs make them particularly interesting for the application as protective coatings. Especially for alloys with a high chromium content, a high corrosion resistance has been revealed. For the current investigations, the equimolar HEA CrFeCoNi with a single-phase face centered cubic structure is considered as a base alloy system. To increase the corrosion resistance as well as the hardness and strength, the influence of the alloying elements aluminum and molybdenum is analyzed. For the current investigations, the high kinetic process high-velocity oxygen fuel thermal spraying (HVOF) has been considered to produce coatings with a low porosity and oxide content. Feedstock is produced by inert gas atomization. The influence of the alloy composition on the microstructure, phase formation and resulting property profile is studied in detail. A detailed analysis of the corrosion resistance and underlying mechanisms is conducted. The pitting and passivation behavior are investigated by potentiodynamic polarization measurements in NaCl and H2SO4 electrolyte. A distinct improvement of the corrosion resistance can be achieved for the alloy Al0.3CrFeCoNiMo0.2.

Model-Based Analysis of Friction-Induced Sub-Synchronous Whirl for a Rotor Contacting With Clearance Bearings Under Axial Load

2015 ◽  
Author(s):  
Matthew O. T. Cole ◽  
Lawrence Hawkins
Keyword(s):  
Axial Load ◽  
Coulomb Friction ◽  
Friction Forces ◽  
Root Finding ◽  
Model Based ◽  
Simple Physical Interpretation ◽  
Level Of Agreement ◽  
Model Based Analysis

For rotors supported by active magnetic bearings (AMBs), clearance bearings are commonly used to provide backup support under loss of AMB functionality. Test data from real machines shows that rotor vibration during touchdown on backup bearings may involve steady forward whirling at a sub-synchronous frequency. This excitation is believed to be due to friction forces transmitted between the rotor and a bearing end-face under axial load. This paper proposes a new analytical approach to model and predict such friction-driven forward whirl behaviors. A set of constraint equations are derived that relate a circular whirl motion of arbitrary orbital speed to the frequency response functions of the rotor-housing structure. This model is coupled with an evaluation of Coulomb friction associated with slip between the rotor and the supporting end-face of a thrust bearing. The resulting equations can be used to compute a set of possible whirl motions via a root-finding procedure. A case study is undertaken for a 140 kW energy storage flywheel. Model-based predictions are compared with measured data from spin-down tests and show a good level of agreement. The study confirms the role of friction-related forces in driving forward-whirl response behaviors. It also highlights the key role of housing and machine support characteristics in response behavior. This influence is shown to be complex and not open to simple physical interpretation. Therefore, the proposed analytical method is seen as a useful tool to investigate this influence while avoiding the need for time consuming numerical simulations.

scholarly journals Role of Graphene oxide and addition of MoS2 in HDPE matrix for improved tribological properties

2018 ◽  
Vol 376 ◽  
pp. 012077
Author(s):  
G J Naveen ◽  
P SampathKumaran ◽  
Prajwal Badrinath ◽  
S Vynatheya ◽  
R R N Sailaja ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Tribological Properties

Determining role of individual cations in high entropy oxides: Structure and reversible tuning of optical properties

2022 ◽  
Vol 207 ◽  
pp. 114273
Author(s):  
Abhishek Sarkar ◽  
Pavan Kumar Mannava ◽  
Leonardo Velasco ◽  
Chittaranjan Das ◽  
Ben Breitung ◽  
...  
Keyword(s):  
Optical Properties ◽  
High Entropy
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