scholarly journals Tribo-corrosion Behaviour of Bare and Nano-coated Foils Used on High-speed Air Foil Bearings

2021 ◽  
Author(s):  
Khotso Khoele ◽  
Monday Ama Onoyivwe ◽  
Ray Suprakas ◽  
Ambimbola Patricia Popoola ◽  
David Desai ◽  
...  
Keyword(s):  
High Speed ◽  
Corrosion Behaviour ◽  
Testing Machine ◽  
Young Modulus ◽  
Wear Rates ◽  
Foil Bearings ◽  
Frictional Wear ◽  
Wear And Friction ◽  
Surface Morphologies ◽  
Temperature Surface

Abstract Irrespective of applying lubricants between high-speed machinery’s shafts and Air-foil bearings (AFBs), wear and friction remain troublesome. Hence, the present study sought novel bare foil and equivalent nanocomposites to form a coating system that could mitigatly lower frictional wear between high-speed machinery’s shafts and Air-foil bearings (AFBs). Bare and coated foils were supplied on rectengular dimensions of 15 × 15 × 5mm3. Mechanical properties were characterized by Instron 3384 testing machine. Universal Tribometer s/n : RTEC2441, USA was utilized for tribological measurements at room temperature. Surface morphologies were examined by Scanning electron microscopy (SEM). Higher hardness and young modulus values were recorded from coated foils. On the other hand, specific wear rates were relatively low from coated foils. Furthermore, abrasive wear index was higher from the F2 coated foil. Friction coeffients were also lower from the coated foils under all engaged tribological conditions. Highly ruptured SEM morphologies were noticed from the bare foil. Nonetheless, mild and negligible aggressions were discovered from the surfaces of nano-coated foils.

Wear and Friction Properties of TiN,TiAlN and CrAlN PVD Coatings

2011 ◽  
Vol 697-698 ◽  
pp. 436-439
Author(s):  
Ai Hua Liu ◽  
Jian Xin Deng ◽  
Hui Zhang ◽  
Yun Song Lian ◽  
Jun Zhao
Keyword(s):  
High Speed ◽  
Test System ◽  
Hard Coatings ◽  
Wear Behaviour ◽  
Test Results ◽  
Pvd Coatings ◽  
Wear Rates ◽  
Wear And Friction ◽  
Wear Tests ◽  
Ball On Disc

The paper reports a comparative study of the tribological properties of the most employed hard coatings like TiN, TiAlN and CrAlN. Ball-on-disc wear tests were performed on the CETR UMT-2 test system against Si3N4balls with a relatively high speed of 100m/min. The coating character and test results were obtained through SEM, XRD and Wyko surface profilometer. The results are as follows: The friction coefficients of the three coatings are relatively high because of the superabundant wear debris during tests. The wear behaviour and wear tracks exist distinct differences for different coatings. As for wear rates, the sequence of three coatings is TiN>TiAlN>CrAlN, the combination property of CrAlN is the best.

Tribological Properties of Fe-Cu-MoS2 and Self-Lubricating Behaviors

2011 ◽  
Vol 268-270 ◽  
pp. 389-394 ◽  
Author(s):  
Chuan Qi Fu ◽  
Jun Cai Sun ◽  
Zhou Wang
Keyword(s):  
Tribological Properties ◽  
Testing Machine ◽  
High Wear Resistance ◽  
Solid Solution Alloy ◽  
Wear Properties ◽  
Wear Rates ◽  
Mechanical And Tribological Properties ◽  
Temperature Load ◽  
Surface Morphologies ◽  
Hot Press Sintering

The Fe-Cu-MoS2composites with different adding amount of MoS2as lubricant were prepared by induction sintering method. Their mechanical and tribological properties from room temperature (RT) to 800°C were tested by universal testing machine and high temperature tribometer. The effects of amounts of MoS2, temperature, load and sliding distance on the friction and wear properties of composite were discussed. The structure of the composite was analyzed by XRD and worm surface morphologies were observed by SEM. It was found that MoS2was decomposed during the hot-press sintering process. Meanwhile, solid solution alloy of Mo and Fe, and sulfides were formed in composite, which were responsible for low-friction and high wear-resistance at elevated temperature, respectively. Hardness and anti-compress strength can be improved by adding 8 wt. % MoS2. The friction coefficients and wear rates of composites decrease with the increase of adding amount of MoS2until a critical value of 8 wt. %. The composite with 8 wt. % MoS2shows the optimum tribological properties over the temperature range of RT~800°C.

Magne´li-Type Phases for Dry High-Speed Sliding Applications Up to 800°C

2005 ◽  
Author(s):  
M. Woydt ◽  
N. Ko¨hler ◽  
N. Kelling
Keyword(s):  
Boundary Lubrication ◽  
High Speed ◽  
Mixed Boundary ◽  
Operating Conditions ◽  
Thermal Cycles ◽  
Wear Rates ◽  
Foil Bearings ◽  
Foil Bearing

The wear rates established up to 800°C and 7,5 m/s qualify the new and non-commercial available metallurgical concepts (Ti,Mo)(C,N) and Tin-2Cr2O2n-1 qualify both metallurgical concepts for radial and axial air foil bearings in small jet turbines, APUs and turbochargers, but are not limited to these, as well as the values of wear rates are comparable to those typically attributed under mixed/boundary lubrication of liquid lubricated tribosystems. The selection between (Ti,Mo)(C,N) and Tin-2Cr2O2n-1 under tribological considerations depends from the operating conditions and thermal cycles of the regarded foil bearing.

Study on Frictional Wear Property of the High Vanadium High Speed Steel

2010 ◽  
Vol 458 ◽  
pp. 252-257 ◽  
Author(s):  
Hui Min Chen ◽  
Liu Jie Xu
Keyword(s):  
Carbon Content ◽  
Retained Austenite ◽  
High Speed ◽  
Testing Machine ◽  
High Speed Steel ◽  
Frictional Resistance ◽  
Wear Testing ◽  
Wear Property ◽  
Frictional Wear ◽  
The Matrix

The frictional resistance and abrasion mechanism of high vanadium high speed steel were studied by the self-made friction wear testing machine under the conditions of 10% slip-roll ratio. Results show that the frictional resistance increases with the increase of carbon content and is optimal when the carbon content is 2.92%. The carbon content affect the wear resistance by changing the amount of the retained austenite and the shapes of carbides, the moderate quantities of retained austenite makes the matrix have better impact toughness and hardness; The spherical VC can prevent the initiation and expansion of cracks forming and make the frictional resistance increase. The abrasion mechanism is fatigue flake under the condition of rolling and sliding.

Tribotechnical characteristics of hard alloys in sliding friction units

2020 ◽  
pp. 87-97
Author(s):  
K. D. Khromushkin ◽  
B. G. Ushakov ◽  
A. V. Kochergin ◽  
R. A. Suleev ◽  
O. N. Parmenova
Keyword(s):  
Experimental Data ◽  
Sliding Friction ◽  
Heating Temperature ◽  
Hard Alloys ◽  
Friction Units ◽  
Wear And Friction ◽  
Friction Path ◽  
Friction Parameters ◽  
Tribotechnical Characteristics ◽  
Temperature Surface

The paper presents experimental data on the study of the friction parameters of hard alloys in sliding friction units, including the heating temperature, surface roughness, wear and friction coefficient, depending on the duration of the test and the friction path.

Rotordynamic Performance of a Rotor Supported on Bump Type Foil Gas Bearings: Experiments and Predictions

2006 ◽  
Vol 129 (3) ◽  
pp. 850-857 ◽  
Author(s):  
Luis San Andrés ◽  
Dario Rubio ◽  
Tae Ho Kim
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Load Capacity ◽  
Test System ◽  
Foil Bearings ◽  
Rotor Imbalance ◽  
Synchronous Motion ◽  
Damping Characteristics ◽  
Rotor Surface ◽  
Stiffness And Damping

Gas foil bearings (GFBs) satisfy the requirements for oil-free turbomachinery, i.e., simple construction and ensuring low drag friction and reliable high speed operation. However, GFBs have a limited load capacity and minimal damping, as well as frequency and amplitude dependent stiffness and damping characteristics. This paper provides experimental results of the rotordynamic performance of a small rotor supported on two bump-type GFBs of length and diameter equal to 38.10mm. Coast down rotor responses from 25krpm to rest are recorded for various imbalance conditions and increasing air feed pressures. The peak amplitudes of rotor synchronous motion at the system critical speed are not proportional to the imbalance introduced. Furthermore, for the largest imbalance, the test system shows subsynchronous motions from 20.5krpm to 15krpm with a whirl frequency at ∼50% of shaft speed. Rotor imbalance exacerbates the severity of subsynchronous motions, thus denoting a forced nonlinearity in the GFBs. The rotor dynamic analysis with calculated GFB force coefficients predicts a critical speed at 8.5krpm, as in the experiments; and importantly enough, unstable operation in the same speed range as the test results for the largest imbalance. Predicted imbalance responses do not agree with the rotor measurements while crossing the critical speed, except for the lowest imbalance case. Gas pressurization through the bearings’ side ameliorates rotor subsynchronous motions and reduces the peak amplitudes at the critical speed. Posttest inspection reveal wear spots on the top foils and rotor surface.

An experimental investigation of a microturbine simulated rotor supported on multileaf gas foil bearings with backing bump foils

2017 ◽  
Vol 232 (9) ◽  
pp. 1169-1180 ◽  
Author(s):  
Bo Zhang ◽  
Shemiao Qi ◽  
Sheng Feng ◽  
Haipeng Geng ◽  
Yanhua Sun ◽  
...  
Keyword(s):  
High Speed ◽  
Preliminary Test ◽  
Journal Bearings ◽  
Rotating Machinery ◽  
System Stability ◽  
Test Rig ◽  
Thrust Bearings ◽  
Foil Bearings ◽  
Simulated System ◽  
First Time

Two multileaf gas foil journal bearings with backing bump foils and one set of gas foil thrust bearings were designed, fabricated, and used in a 100 kW class microturbine simulated rotor system to ensure stability of the system. Meanwhile, a preliminary test rig had been built to verify the simulated system stability. The rotor synchronous and subsynchronous responses were well controlled by using of the gas foil bearings. It is on the multileaf gas foil bearings with backing bump foils that the test was conducted and verified for the first time in open literatures. The success in the experiments shows that the design and fabrication of the rotor and the gas foil bearings can provide a useful guide to the development of the advanced high speed rotating machinery.

Analysis of high speed permanent magnet synchronous motor rotor supported by air foil bearings

2019 ◽  
Vol 59 (2) ◽  
pp. 755-764
Author(s):  
Hao Lin ◽  
Haipeng Geng ◽  
Tingchen Du ◽  
Xiangming Xu ◽  
Yanyan Zhang ◽  
...  
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Permanent Magnet Synchronous Motor ◽  
Synchronous Motor ◽  
Foil Bearings

Effect of Methane Flow Rate on the Microstructural and Mechanical Properties of Silicon Carbide Thin Films Deposited by Reactive DC Magnetron Sputtering

2010 ◽  
Vol 66 ◽  
pp. 35-40 ◽  
Author(s):  
Erdem Baskurt ◽  
Tolga Tavşanoğlu ◽  
Yücel Onüralp
Keyword(s):  
Magnetron Sputtering ◽  
High Speed ◽  
Profile Analysis ◽  
High Speed Steel ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Cross Sectional ◽  
Methane Flow Rate ◽  
Surface Morphologies ◽  
Sic Films

SiC films were deposited by reactive DC magnetron sputtering of high purity (99.999%) Si target. 3 types of substrates, AISI M2 grade high speed steel, glass and Si (100) wafer were used in each deposition. The effect of different CH4 flow rates on the microstructural properties and surface morphologies were characterized by cross-sectional FE-SEM (Field-Emission Scanning Electron Microscope) observations. SIMS (Secondary Ion Mass Spectrometer) depth profile analysis showed that the elemental film composition was constant over the whole film depth. XRD (X-Ray Diffraction) results indicated that films were amorphous. Nanomechanical properties of SiC films were also investigated.

Rotordynamics Performance of Hybrid Foil Bearing Under Forced Vibration Input

2017 ◽  
Author(s):  
Daejong Kim ◽  
Brian Nicholson ◽  
Lewis Rosado ◽  
Garry Givan
Keyword(s):  
Impulse Response ◽  
High Speed ◽  
Load Capacity ◽  
Supply System ◽  
Forced Response ◽  
Experimental Results ◽  
Lateral Acceleration ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Gas Supply

Foil bearings are one type of hydrodynamic air/gas bearings but with a compliant bearing surface supported by structural material that provides stiffness and damping to the bearing. The hybrid foil bearing (HFB) in this paper is a combination of a traditional hydrodynamic foil bearing with externally-pressurized air/gas supply system to enhance load capacity during the start and to improve thermal stability of the bearing. The HFB is more suitable for relatively large and heavy rotors where rotor weight is comparable to the load capacity of the bearing at full speed and extra air/gas supply system is not a major added cost. With 4,448N∼22,240N thrust class turbine aircraft engines in mind, the test rotor is supported by HFB in one end and duplex rolling element bearings in the other end. This paper presents experimental work on HFB with diameter of 102mm performed at the US Air force Research Laboratory. Experimental works include: measurement of impulse response of the bearing to the external load corresponding to rotor’s lateral acceleration of 5.55g, forced response to external subsynchronous excitation, and high speed imbalance response. A non-linear rotordynamic simulation model was also applied to predict the impulse response and forced subsynchronous response. The simulation results agree well with experimental results. Based on the experimental results and subsequent simulations, an improved HFB design is also suggested for higher impulse load capability up to 10g and rotordynamics stability up to 30,000rpm under subsynchronous excitation.

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