Effect of substrate surface roughness on the wear of molybdenum disulphate coated rolling contact bearings

2021 ◽  
Vol 63 (9) ◽  
pp. 848-854
Author(s):  
Bahar Gokce ◽  
Necdet Geren ◽  
Mahmut Izciler
Keyword(s):  
High Temperature ◽  
Molybdenum Disulfide ◽  
Substrate Surface ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Wear Testing ◽  
Wear Depth ◽  
Phosphate Coating ◽  
Depth Measurement ◽  
Friction Moment

Abstract The objective of the present experimental work is to investigate the influence of subsurface roughness on the friction and wear performance of high-temperature ball bearing. Bearings, which are used in high-temperature applications, are affected by several operating conditions. Some factors under high-temperature conditions such as short grease life, thin-film thickness at low speed, and insufficient internal clearance can drastically reduce bearing service life due to an increase in surface friction. For this reason, rolling contact bearings are coated with molybdenum disulfide. Before the molybdenum disulfide (MoS2) coating, phosphatization is applied to the bearings. Because the phosphate layer is micro-porous, it assures that molybdenum disulfide is entrapped in the interstitials between the phosphates. Also, phosphate coating provides a much larger surface area for the lubricant to attach to. In this study, several process steps, sandblasting, manganese phosphate coating, molybdenum disulfide coating, friction moment testing, wear testing, wear depth measurement, SEM, and XRD analyses were carried out. Wear tests and friction moment tests were applied to the rings of bearings of varied raceway roughness. This process ultimately provides molybdenum disulfide coated bearings optimum raceway roughness parameters for good wear resistance and optimum boundary lubrication.

Numerical prediction of the development of rail wear on high-speed railways

2019 ◽  
Vol 234 (9) ◽  
pp. 927-944
Author(s):  
Pu Wang ◽  
Shuguo Wang ◽  
Liang Gao
Keyword(s):  
High Speed ◽  
Numerical Prediction ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Wear Depth ◽  
Curve Section ◽  
High Speed Railway ◽  
Rail Wear ◽  
The Difference ◽  
Circular Curve

In this paper, a numerical prediction model was established to investigate the development of rail wear on high-speed railways, and a corresponding program was written using Matlab. According to Archard’s material wear theory, the wear depth distribution in the wheel–rail contact patch and along the rail profile was calculated based on a simulation of vehicle–track dynamics and a wheel–rail rolling contact analysis. In the dynamics model, various structural components and the complex nonlinear interactions between components were precisely simulated to ensure consistency with reality. Simulations were then conducted for every possible load case, and dimensionless weight factors were introduced to model the diverse operating conditions of a high-speed railway. An adaptive step algorithm was adopted to iteratively update the rail profile and reduce cumulative deviation or errors, improving the stability and reliability of the numerical model. Finally, a case study was conducted to investigate the development of wear in different track sections on a high-speed railway using the developed model. The results indicated that in the circular curve and transition sections, the side wear of the outer rail was obvious, and the wear of the inner rail was relatively smaller and mostly distributed in the middle of the railhead. The wear of the outer rail was more severe in the circular curve section compared to that in the transition sections. The closer to the rail shoulder, the greater the difference between the wear in the circular curve section and that in the transition section. In the tangent section, the wear of both rails was similarly distributed in the middle of the railhead and far less severe than in either the circular curve or transition sections. The agreement between the calculated results and field observations verified the rationality of the established rail wear model, which shows promise for improving the maintenance planning of high-speed railways and furthering the understanding of the rail wear processes.

Trends in the development of flexible thermal protection systems for modern aircraft

2020 ◽  
pp. 10-21
Author(s):  
V. G. Babashov ◽  
◽  
N. M. Varrik ◽  
Keyword(s):  
High Temperature ◽  
Thermal Protection ◽  
Heat Removal ◽  
Operating Conditions ◽  
Passive Protection ◽  
Thermal Protection Systems ◽  
Heat Protection ◽  
Protection Systems ◽  
Protected Surface ◽  
Flexible Panels

The emergence of new types of space and aviation technology necessitates the development of new types of thermal protection systems capable of operating at high temperature and long operating times. There are several types of thermal protection systems for different operating conditions: active thermal protection systems using forced supply of coolant to the protected surface, passive thermal protection systems using materials with low thermal conductivity without additional heat removal, high-temperature systems, which are simultaneously elements of the bearing structure and provide thermal protection, ablation materials. Heat protection systems in the form of rigid tiles and flexible panels, felt and mats are most common kind of heat protecting systems. This article examines the trends of development of flexible reusable heat protection systems intended for passive protection of aircraft structural structures from overheating.

UNITEMP HX

Alloy Digest ◽  
1964 ◽  
Vol 13 (5) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Base Material ◽  
Heat Treating ◽  
Operating Conditions ◽  
High Temperature Strength ◽  
Temperature Performance ◽  
Nickel Base

Abstract Unitemp-HX is a nickel-base material recommended for high temperature applications. It has outstanding oxidation resistance at high temperatures under most operating conditions, and good high-temperature strength. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-91. Producer or source: Universal Cyclops Steel Corporation.

HASTELLOY ALLOY X

Alloy Digest ◽  
1954 ◽  
Vol 3 (12) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Heat Treating ◽  
Operating Conditions ◽  
Molybdenum Alloy ◽  
High Temperature Strength ◽  
Nickel Chromium

Abstract HASTELLOY Alloy X is a nickel-chromium-iron-molybdenum alloy recommended for high-temperature applications. It has outstanding oxidation resistance at high temperatures under most operating conditions, and good high-temperature strength. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on forming, heat treating, and machining. Filing Code: Ni-14. Producer or source: Haynes Stellite Company.

REMANIT 4306

Alloy Digest ◽  
1997 ◽  
Vol 46 (4) ◽  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Austenitic Stainless Steel ◽  
Cold Working ◽  
Heat Treating ◽  
Operating Conditions ◽  
Low Carbon ◽  
Corrosion Resistant ◽  
Temperature Performance

Abstract Remanit 4306 is a low-carbon chromium nickel austenitic stainless steel that is superior in corrosion resistance to type 302 (see Alloy Digest SS-99, revised September 1998). Due to its low carbon content, Remanit 4306 is intergranular corrosion resistant under continuous operating conditions up to 350 C (652 F). This grade is particular suitable for high degrees of cold working and for sequential drawing. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-679. Producer or source: Thyssen Stahl AG.

A NEW WELDING MATERIAL FOR REGENERATION IN THE WELDING TECHNOLOGY BASED ON NICKEL. ANALYSIS OF THE COMPOSITION AND PROPERTIES OF DEFORMABLE HEAT-RESISTANT HIGH-CHROMIUM NICKEL-BASED ALLOYS FOR WELDED PARTS. ANALYSIS OF EXISTING FUELLING STATIONS TYPES AND VEHICLES USING HYDROGEN, HYDROGEN PRODUCTION AND STORING METHODS

2019 ◽  
pp. 43-48
Author(s):  
Ben Nengjun ◽  
Zhou Pengfei ◽  
Oleksandr Labartkava ◽  
Mykhailo Samokhin
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Nickel Alloys ◽  
Total Content ◽  
Operating Conditions ◽  
High Temperature Strength ◽  
High Chromium ◽  
Salt Corrosion ◽  
Tcp Phases ◽  
The Impact

This work involves an analysis of high-chromium high-temperature deformable wieldable nickel alloys for use in GTE repair assemblies. It is shown that the alloys EP868 (VZh98) and Haynes 230 can be used in welded assemblies with an operating temperature of 800-1100 °C. The alloys Nimonic 81, Nimonic 91, IN 935, IN 939, and Nicrotan 2100 GT also have a high potential for use in welded assemblies. They are characterized by a combination of good weldability, high-temperature strength, and resistance to scaling. There have been conducted studies on high-temperature salt corrosion of model nickel alloys. They allowed establishing the patterns of the impact of base metal alloying with chromium, aluminum, titanium, cobalt, tungsten, molybdenum, niobium, tantalum and rare earth metals on the critical temperature of the start of salt corrosion Tcor and the alloy mass loss. It has been established that alloys with a moderate concentration (13-16%) of chromium can possess satisfactory hightemperature corrosion resistance (HTC resistance) under the operating conditions of ship GTE. The HTC resistance of CrAl-Ti alloys improves upon reaching the ratio Ti/Al ˃ 1. Meanwhile, the ratio Ti/Al ˂ 1 promotes the formation of corrosion products with low protective properties. The positive effect of tantalum on the HTC resistance of alloys is manifested at higher test temperatures than that of titanium, and the total content of molybdenum and tungsten in alloys is limited by the condition 8Mo2 – 2W2 = 89. The presence of refractory elements stabilizes the strengthening phase and prevents formation of the ɳ-phase. However, their excess promotes formation of the embrittling topologically close packed (TCP) phases and boundary carbides of an unfavorable morphology. Based on the studies of the HTC resistance, there has been identified a class of model high-temperature corrosionresistant nickel alloys with a moderate or high chromium content (30%), Ti/Al ˃ 1, and a balanced content of refractory and rare-earth elements.

Effect of Carbide Content on Temper Embrittlement of 2.25Cr1Mo Steel

2016 ◽  
Author(s):  
Yian Wang ◽  
Guoshan Xie ◽  
Zheng Zhang ◽  
Xiaolong Qian ◽  
Yufeng Zhou ◽  
...  
Keyword(s):  
High Temperature ◽  
Pressure Vessel ◽  
High Stress ◽  
Temper Embrittlement ◽  
Damage Mechanism ◽  
Pressure Vessels ◽  
Nondestructive Method ◽  
Operating Conditions ◽  
Low Alloy Steels ◽  
Carbide Content

Temper embrittlement is a common damage mechanism of pressure vessels in the chemical and petrochemical industry serviced in high temperature, which results in the reduction of roughness due to metallurgical change in some low alloy steels. Pressure vessels that are temper embrittled may be susceptible to brittle fracture under certain operating conditions which cause high stress by thermal gradients, e.g., during start-up and shutdown. 2.25Cr1-Mo steel is widely used to make hydrogenation reactor due to its superior combination of high mechanical strength, good weldability, excellent high temperature hydrogen attack (HTHA) and oxidation-resistance. However, 2.25Cr-1Mo steel is particularly susceptible to temper embrittlement. In this paper, the effect of carbide on temper embrittlement of 2.25Cr-1Mo steel was investigated. Mechanical properties and the ductile-brittle transition temperature (DBTT) of 2.25Cr-1Mo steel were measured by tensile test and impact test. The tests were performed at two positions (base metal and weld metal) and three states (original, step cooling treated and in-service for a hundred thousand hours). The content and distribution of carbides were analyzed by scanning electron microscope (SEM). The content of Cr and Mo elements in carbide was measured by energy dispersive X-ray analysis (EDS). The results showed that the embrittlement could increase the strength and reduce the plasticity. Higher carbide contents appear to be responsible for the higher DBTT. The in-service 2.25Cr-1Mo steel showed the highest DBTT and carbide content, followed by step cooling treated 2.25Cr-1Mo steel, while the as-received 2.25Cr-1Mo steel has the minimum DBTT and carbide content. At the same time, the Cr and Mo contents in carbide increased with the increasing of DBTT. It is well known that the specimen analyzed by SEM is very small in size, sampling SEM specimen is convenient and nondestructive to pressure vessel. Therefore, the relationship between DBTT and the content of carbide offers a feasible nondestructive method for quantitative measuring the temper embrittlement of 2.25Cr-1Mo steel pressure vessel.

Applications of vibro-acoustic measurement and analysis in conjunction with tribological parameters to assess surface fatigue wear developed in the roller-bearing system

2021 ◽  
pp. 135065012098246
Author(s):  
Shashikant Pandey ◽  
Muniyappa Amarnath
Keyword(s):  
Roller Bearing ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Stribeck Curve ◽  
Fatigue Wear ◽  
Surface Fatigue ◽  
Rolling Element ◽  
Measurement And Analysis ◽  
Contact Surfaces ◽  
Bearing System

Rolling-element bearings are the most commonly used components in all rotating machinery. The variations in the operating conditions such as an increase in the number of operating cycles, load, speed, service temperature, and lubricant degradation result in the development of various defects such as pitting, spalling, scuffing, scoring, etc. The defects that appeared on rolling contact surfaces cause surface deterioration and change in the vibration and sound levels of the bearing system. The present experimental investigations are aimed at assessing the surface fatigue wear that appears on the contact surfaces of roller bearings. The studies considered the estimation of specific film thickness, analysis of surface fatigue wear developed on the rolling-element surfaces, surface roughness analysis, grease degradation analysis using Fourier transform infrared radiation, and vibration and sound signal measurement and analysis. The results obtained from the experimental investigation provide a good correlation between surface wear, vibration, and sound signals with a transition in the lubrication regimes in the Stribeck curve.

scholarly journals Measurements and Analysis of AC Losses in HTS Windings of Electrical Machine for Different Operation Modes

2021 ◽  
Vol 11 (6) ◽  
pp. 2741
Author(s):  
Sergey Zanegin ◽  
Nikolay Ivanov ◽  
Vasily Zubko ◽  
Konstantin Kovalev ◽  
Ivan Shishov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
High Temperature Superconductor ◽  
High Temperature Superconductors ◽  
Transport Current ◽  
Operating Conditions ◽  
Ac Losses ◽  
Electrical Machine ◽  
2Nd Generation ◽  
Motor Mode

The article is devoted to the study of losses in devices based on high-temperature superconductors of the 2nd generation. The complexity of the devices under study increases from a single rack coil to a winding assembled from several coils, and finally to an electric machine operating in generator mode. This is the way to experimentally study the behavior of 2nd generation high temperature superconductor (2G HTS) carrying a transport current in various conditions: self-field, external DC, and AC magnetic field. Attention is also paid to the losses in the winding during its operation from the inverter, which simulates the operating conditions in the motor mode of a propulsion system.

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