Lubrication at High Temperatures With Vapor-Deposited Surface Coatings

1961 ◽  
Vol 83 (2) ◽  
pp. 133-138 ◽  
Author(s):  
D. J. Baldwin ◽  
G. W. Rowe
Keyword(s):  
Experimental Study ◽  
Stainless Steel ◽  
High Temperature ◽  
Boron Nitride ◽  
High Temperatures ◽  
Indentation Test ◽  
Surface Coatings ◽  
Molybdenum Disulphide ◽  
High Coefficient ◽  
Inorganic Films

An experimental study of the friction of metals which have been coated with inorganic films by reaction with their surrounding atmosphere. The specimens are first cleaned at high temperature in vacuo and then heated in the selected reactive vapor. Many coatings will prevent seizure and give a fairly constant but high coefficient of friction up to high temperatures. Layer-lattice compounds such as MoS2, CrCl3, and TiI2 give much lower friction at all temperatures below those at which the film decomposes or evaporates (about 850 C for molybdenum disulphide). A film of boron nitride formed on boron shows a high intrinsic friction, but this can be reduced by certain vapors or by raising the temperature above about 800 C. Most of the experiments were performed with very light loads but the films are shown to be effective under kilogram loads. A simple indentation test capable of selecting lubricants under loads up to 12 tons is described. This shows that a film formed by heating stainless steel in CCl2F2 will lubricate at 400 C when the steel is deformed by over 50 per cent.

scholarly journals Characterization and modelling of both high-cycle hightemperature fatigue behaviour of Stainless Steel Grades

2018 ◽  
Vol 165 ◽  
pp. 19008
Author(s):  
Pierre-Olivier Santacreu ◽  
Cloé Prudhomme ◽  
Benoit Proult ◽  
Isabelle Evenepoel
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
High Temperatures ◽  
High Cycle Fatigue ◽  
Fatigue Cracks ◽  
Fatigue Behaviour ◽  
Cycle Fatigue ◽  
Vibration Fatigue ◽  
Steel Grades ◽  
Stress Ratios

In the same context of thermo-mechanical fatigue and high temperature applications of stainless steel, high-frequency vibration fatigue at high temperatures should be considered, in particular for automotive exhaust gas applications. In fact one of the most frequent incidents that can happen on exhaust components is an accumulation of low-cycle thermal fatigue and high-cycle fatigue. The prediction of the lifetime of a structure under such complex thermal and mechanical loading is therefore a constant challenge at high temperature due to the coupling of metallurgical, oxidation or creep effects. In order to better understand in a first approach, the high cycle fatigue of stainless steels at high temperatures, tractioncompression tests were performed on flat specimens at 25Hz, under air and in isothermal conditions from ambient temperature to 850°C. Two different stress ratios, R=-1 and 0.1, are characterized with the objective to assess a multiaxial model for high temperature. Different criteria are used to predict the ruin of a structure under high-cycle fatigue but in general for ambient-around temperatures. In particular, multiaxial and stress-based DangVan criterion is today widely used to evaluate the risk of fatigue cracks initiation and it has been implemented recently in our fatigue life processor Xhaust_Life®. Therefore the Dang Van criterion was identified from the isothermal high cycle fatigue using the 2 stress ratio and its validity is discussed especially for temperatures higher than 500°C where strain rate and creep effects have increasing influence. Results are presented for two ferritic stainless steel grades used in high temperature exhaust applications: K41X (AISI 441, EN 1.4509) and K44X (AISI 444Nb, EN 1.4521).

Instrumented Indentation Testing to Evaluate High-Temperature Material Properties

2011 ◽  
Author(s):  
Chan-Pyoung Park ◽  
Kug-Hwan Kim ◽  
Seung-Kyun Kang ◽  
Won-Je Jo ◽  
Dongil Kwon
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Material Properties ◽  
Indentation Test ◽  
Temperature Deformation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Indentation Testing ◽  
Instrumented Indentation ◽  
Uniaxial Tensile Testing

Mechanical properties must be evaluated at high temperatures to predict high-temperature deformation and fracture behavior, since high-temperature properties differ greatly from those at room temperature. A high-temperature uniaxial tensile test, a representative high-temperature test, is generally used, but it has the limitation of obtaining merely the average material properties. Recently an advanced method for evaluating tensile properties has been developed: the instrumented indentation test (IIT), which simultaneously applies a load and measures displacement. Here we use instrumented indentation testing to evaluate the flow properties (yield strength, ultimate tensile strength, etc.) of heat-resistant steel at high temperature. The contact-area determination algorithm and representative stress-representative strain approach are applied for high temperatures. We compare our experimental results to those of conventional high-temperature uniaxial tensile testing to assess the high-temperature performance of the instumented indentation test.

scholarly journals Thermomechanical fatigue behaviour of ferritic stainless steel grades for high temperatures applications

2018 ◽  
Vol 165 ◽  
pp. 16003
Author(s):  
Cloé Prudhomme ◽  
Pierre-Olivier Santacreu ◽  
Isabelle Evenepoel ◽  
Benoit Proult
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
High Temperatures ◽  
Thermal Loading ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Thermomechanical Fatigue ◽  
Compression Tests ◽  
Wide Range ◽  
Steel Grades

Nowadays high temperatures resistant materials are needed to resist to high temperature applications (up to 1000°C), such as automotive exhaust gas manifolds. Some developed stainless steel grades, including ferritic grades or austenitic refractory grades, can be used in this temperature range and both in continuous or cyclic thermal conditions. In order to predict the thermomechanical fatigue damage of stainless steel parts submitted to cyclic thermal loading and constrained bonding conditions, the elastoviscoplastic model by Chaboche is determined for a wide range of temperatures, of strain amplitudes and strain rate levels thanks to isothermal traction-compression tests. The validation procedure is performed afterward by comparison with stabilized behavior under non isothermal conditions on a dedicated thermal fatigue test performed on V-shape specimens. Results of simulation show very good fitting with the experimental curves which would lead to a more accurate fatigue life prediction. A damage model was derived from Taira’s thermal low-cycle fatigue model to include dwell-time period at high temperature and creep-oxidation effect. In this paper the example of K44X, a dedicated grade for high temperatures applications, is presented.

An Experimental Investigation of Fuel Additives in a Supercharged Boiler

1960 ◽  
Vol 82 (3) ◽  
pp. 169-178 ◽  
Author(s):  
R. J. Zoschak ◽  
R. W. Bryers
Keyword(s):  
Experimental Investigation ◽  
Stainless Steel ◽  
High Temperature ◽  
Gas Turbine ◽  
High Temperatures ◽  
Power Plants ◽  
High Temperature Corrosion ◽  
Residual Oil ◽  
Test Program ◽  
Corrosive Effect

To permit the use of high-vanadium residual oil as fuel for combined super-charged-boiler gas-turbine power plants, it is necessary to determine the treatment required to prevent the high-temperature corrosion and deposit problems associated with this fuel. A test program has been undertaken wherein a number of magnesium and aluminum-bearing additives have been injected into washed residual oil when firing a laboratory-scale, simulated supercharged boiler. Different tube arrangements within the boiler have been tried. Ash collected on the tubes at various locations has been analyzed and its corrosive effect at high temperatures on some types of stainless steel has been evaluated. The results thus far obtained are presented together with some hypotheses regarding the formation of deposits.

scholarly journals An Experimental Study of Contact Temperatures at Sealing Interface against Varying Shaft Surfaces

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 156
Author(s):  
Sarah Shabbir ◽  
Seamus D. Garvey ◽  
Sam M. Dakka ◽  
Benjamin C. Rothwell
Keyword(s):  
Experimental Study ◽  
Stainless Steel ◽  
Critical Parameter ◽  
Working Life ◽  
Surface Coatings ◽  
Operating Parameters ◽  
Contact Interface ◽  
Oxide Coatings ◽  
Chrome Oxide ◽  
Shed Light

Increased temperatures at the sealing interface between the seal and shaft can reduce the working life of a seal through elastomer aging, swelling and increased friction. Degradation of the seal due to increased temperatures can cause pre-mature failure, wear and leakage. There is no such thing as a perfect seal; each application has requirements to cater to the needs of each system. For radial oil seals in helicopter gearboxes, the contact temperatures at the sealing interface are a critical parameter to consider. In this manuscript, investigating the factors that influence the temperatures at the contact interface shed light on the operating parameters that cause an increase in contact temperatures. Four varying shaft coatings are tested against three seal spring loads for a range of sliding velocities between 5–25 ms−1 to reproduce conditions of the gearbox. The study reveals an optimum seal spring of 12 oz, with a circumferential load of 3.34 N for lowest temperatures at the interface. Higher springs of 14 oz and lower springs of 8.5 oz both cause increased temperatures at the interface. Additionally, the need for surface coatings on the shaft is re-enforced through experimental evidence demonstrated by comparing temperatures reached between a plain stainless steel shaft and three surface coated shafts. Chrome plating shafts are undesirable due to the ‘polishing’ in effect they experience. The results of this study build on this by showing that chrome plated shafts have higher temperatures at the interface, aggravating any wear or polishing in of that surface. Contact temperatures with Tungsten carbide and Chrome oxide coatings remain within the expected temperature rise. Lastly, microscopically ‘rougher’ surfaces result in increased temperatures in contrast to surface coatings within the specified range of roughness as provided by DIN 3760/61/ISO 6194.

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