Tribological Properties Improvement of Mo-Alloyed HfN Films With a High H/E Ratio at Elevated Temperatures

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Zhaoli Liu ◽  
Hang Li ◽  
Jianliang Li ◽  
Jiewen Huang ◽  
Jian Kong ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Tribological Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Structure Stability ◽  
Solid Solution Phase ◽  
High Structure ◽  
Worn Surface ◽  
The Relationship ◽  
Fcc Structure

Abstract In this study, the Mo-alloyed HfN films were prepared by DC-magnetron sputtering and studied their tribological properties at 25–600 °C under dry friction conditions. The relationship between H/E value and tribological properties at elevated temperature was illustrated. A single solid-solution phase was formed for all Hf-Mo-N films which with an FCC structure, and the H/E and H3/E2 values are increased. The film with x = 0.56 obtained a lower friction coefficient (0.4) and wear-rate (1.23 × 10−6 mm3/N m) at room temperature. At elevated temperature, this film maintained high structure stability, meanwhile, a dense and continuous oxide layer with lubrication was formed and tightly covered on the worn surface, that it obtained a lower coefficients of friction and better wear resistance.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

scholarly journals The Effect of Elemental Composition and Nanostructure of Multilayer Composite Coatings on Their Tribological Properties at Elevated Temperatures

2020 ◽  
Author(s):  
Alexey Vereschaka ◽  
Sergey Grigoriev ◽  
Vladimir Tabakov ◽  
Mars Migranov ◽  
Nikolay Sitnikov ◽  
...  
Keyword(s):  
Elemental Composition ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Elevated Temperatures ◽  
Composite Coatings ◽  
Multilayer Composite ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Tribological Parameters ◽  
Adhesion Component

The chapter discusses the tribological properties of samples with multilayer composite nanostructured Ti-TiN-(Ti,Cr,Al,Si)N, Zr-ZrN-(Nb,Zr,Cr,Al)N, and Zr-ZrN-(Zr,Al,Si)N coatings, as well as Ti-TiN-(Ti,Al,Cr)N, with different values of the nanolayer period λ. The relationship between tribological parameters, a temperature varying within a range of 20–1000°C, and λ was investigated. The studies have found that the adhesion component of the coefficient of friction (COF) varies nonlinearly with a pronounced extremum depending on temperature. The value of λ has a noticeable influence on the tribological properties of the coatings, and the nature of the mentioned influence depends on temperature. The tests found that for the coatings with all studied values of λ, an increase in temperature first caused an increase and then a decrease in COF.

Tribological Properties of Hot-Pressed SrSO4 Ceramic at Elevated Temperatures in Dry Sliding Against Alumina Ball

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Chong-Chong Mao ◽  
Yu-Feng Li
Keyword(s):  
Tribological Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Testing Temperature ◽  
Dry Sliding ◽  
Potential Candidate ◽  
Friction Behavior ◽  
Wear Rates ◽  
Brittle To Ductile Transition ◽  
Lubricating Film

SrSO4 ceramic was prepared by hot-pressed sintering and its friction behavior was investigated against the Al2O3 ball under the dry sliding condition from room temperature to 800 °C. From room temperature to 400 °C, the tribological properties of SrSO4 ceramic are quite poor with the friction coefficients of 0.65–0.83 and the wear rates of about 10−3 mm3/Nm. With the testing temperature increasing to 600 °C and 800 °C, a brittle to ductile transition of SrSO4 takes place because of the activated slip systems. The friction coefficient and wear rate of SrSO4 ceramic also obviously decrease to 0.37 and about 10−4 mm3/Nm at 800 °C. The significant improvement of the tribological properties is ascribed to the formation of a smooth and continuous SrSO4 lubricating film with excellent ductility and low shear strength at elevated temperature. SrSO4 is considered to be a potential candidate for high-temperature solid lubricant with excellent lubricity.

The Strength and Ductility of Intermetallic Compounds: Grain Size Effects

1986 ◽  
Vol 81 ◽  
Author(s):  
E.M. Schulson ◽  
I. Baker ◽  
H.J. Frost
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Intermetallic Compounds ◽  
Size Effects ◽  
Nickel Aluminide ◽  
Marked Reduction ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
The Relationship ◽  
Strength And Ductility

Since writing on this subject two years ago [1], a number of developments have occurred, particularly in relation to the mechanical properties of the L12 nickel aluminide Ni3Al. Some elucidate the nature of the yield strength and the extraordinarily beneficial effect of boron on low-temperature ductility. Some others expose, at least in part, the nature of the marked reduction in ductility at elevated temperatures. Another considers the mechanisms dominating creep deformation. Also during this period, contradictions have appeared: the relationship between the yield strength and the grain size, d, at room temperature has been contested, and opposing views of grain refinement on ductility have been reported.This paper reviews these developments. Although broadly directed at intermetallic compounds, the discussion is specific to Ni3Al. The hope is that the knowledge and understanding gained about this compound will benefit the class as a whole.

Experimental Study on the Mechanical Property and Forming Limit of Magnesium Sheet at Elevated Temperatures

2009 ◽  
Author(s):  
Y. Huang ◽  
J. Huang ◽  
J. Cao
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Dome Height ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Magnesium Sheet

Magnesium alloy sheet has received increasing attention in automotive and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. Most of work in the field has been working with the magnesium sheet after annealed around 350°C. In this paper, the as-received commercial magnesium sheet (AZ31B-H24) with thickness of 2mm has been experimentally studied without any special heat treatment. Uniaxial tensile tests at room temperature and elevated temperature were first conducted to have a better understanding of the material properties of magnesium sheet (AZ31B-H24). Then, limit dome height (LDH) tests were conducted to capture forming limits of magnesium sheet (AZ31B-H24) at elevated temperatures. An optical method has been introduced to obtain the stress-strain curve at elevated temperatures. Experimental results of the LDH tests were presented.

scholarly journals Application of a √ area -Approach for Fatigue Assessment of Cast Aluminum Alloys at Elevated Temperature

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1033 ◽  
Author(s):  
Roman Aigner ◽  
Christian Garb ◽  
Martin Leitner ◽  
Michael Stoschka ◽  
Florian Grün
Keyword(s):  
Elevated Temperature ◽  
Fatigue Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Damage Mechanism ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Cast Aluminum ◽  
Fatigue Assessment ◽  
Cast Aluminum Alloys

This paper contributes to the effect of elevated temperature on the fatigue strength of common aluminum cast alloys EN AC-46200 and EN AC-45500. The examination covers both static as well as cyclic fatigue investigations to study the damage mechanism of the as-cast and post-heat-treated alloys. The investigated fracture surfaces suggest a change in crack origin at elevated temperature of 150 ∘ C. At room temperature, most fatigue tests reveal shrinkage-based micro pores as their crack initiation, whereas large slipping areas occur at elevated temperature. Finally, a modified a r e a -based fatigue strength model for elevated temperatures is proposed. The original a r e a model was developed by Murakami and uses the square root of the projected area of fatigue fracture-initiating defects to correlate with the fatigue strength at room temperature. The adopted concept reveals a proper fit for the fatigue assessment of cast Al-Si materials at elevated temperatures; in detail, the slope of the original model according to Murakami should be decreased at higher temperatures as the spatial extent of casting imperfections becomes less dominant at elevated temperatures. This goes along with the increased long crack threshold at higher operating temperature conditions.

Measurement of the Aging of Rubber Vulcanizates

1960 ◽  
Vol 33 (2) ◽  
pp. 502-509 ◽  
Author(s):  
J. Mandel ◽  
F. L. Roth ◽  
M. N. Steel ◽  
R. D. Stiehler
Keyword(s):  
Aging Process ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Arrhenius Equation ◽  
Effective Means ◽  
Ultimate Elongation ◽  
Rubber Compounds ◽  
The Relationship

Abstract Ultimate elongation (strain at failure) can be used to assess the aging of all rubber vulcanizates. For this purpose, it appears that Equation (2) can be used to express the early part of the aging process, corresponding to a period of aging at room temperature of 10 or more years. Prediction of shelf aging from tests at two or more elevated temperatures is only possible if the relationship between aging and temperature is known. For some rubber compounds the Arrhenius equation appears to hold. In these instances, it provides an effective means for estimating shelf aging.

Preparation and Tribological Behavior of Self-Lubrication Composites Ni-W-Cr-Fe-Cu-MoS2-Graphite at Elevated Temperature

2013 ◽  
Vol 668 ◽  
pp. 3-8 ◽  
Author(s):  
Jian Rong Sun ◽  
Chang Sheng Li ◽  
Hua Tang ◽  
Zhi Cheng Guo ◽  
Jin Ying Zi Liu
Keyword(s):  
Tensile Strength ◽  
Elevated Temperature ◽  
Powder Metallurgy ◽  
Friction Coefficient ◽  
Tribological Properties ◽  
Room Temperature ◽  
Tribological Behavior ◽  
Strengthening Effect ◽  
Wear Rates ◽  
Increasing Temperature

The composites of Ni-W-Cr-Fe-Cu-MoS2-Graphite with nano-MoS2 were prepared by powder metallurgy. Its tribological properties were investigated using the UTM-2 Nano+Micro Tribometer from room temperature to 600°C. The effects of amount of MoS2 and Ni-W-Cr prealloy powder, load, and temperature on the tribological properties were investigated and discussed. The results indicated that the addition of 43~45wt.% Ni-W-Cr prealloy powder had a strengthening effect on the hardness, anti-press and tensile strength. The tensile strength of the composite decreases with the addition of Nano-MoS2 and graphite, and the friction coefficient decrease with increase of the additives over the wide temperature range of 25°C∼600°C. The friction coefficients and wear rates of the composites reach the optimization value at 2.5wt.% MoS2,While its wear rates increase with the increasing temperature and load.

Sliding Behavior of Alumina/Nickel and Alumina/Nickel Aluminide Couples at Room and Elevated Temperature

1988 ◽  
Vol 110 (4) ◽  
pp. 646-652 ◽  
Author(s):  
Peter J. Blau ◽  
Charles E. DeVore
Keyword(s):  
Elevated Temperature ◽  
Friction Coefficient ◽  
Nickel Aluminide ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Sliding Friction ◽  
Surface Damage ◽  
Polycrystalline Alumina ◽  
Ordered Intermetallic ◽  
Pin On Disk

Nickel aluminide alloys are ordered intermetallic compounds which show promise for elevated temperature applications, some of which involve sliding contact. The present investigation was conducted to develop an initial understanding of the unlubricated sliding behavior of a nickel aluminide alloy at room and elevated temperatures. In particular, the variations in the friction coefficient and the wear track morphology during the break-in stage and subsequent transitions were studied. Pin-on-disk experiments were conducted at room temperature and at 650° C (923° K) in air using fixed 9.5 mm diameter polycrystalline alumina balls as the pin material. To provide a comparison in behavior, nickel (Ni-200) disks were tested under the same conditions. The sliding friction coefficient of alumina on nickel aluminide was considerably higher than that for alumina on nickel at room temperature, but it was only slightly higher at 650° C. The wear was similar for both materials at room temperature, but the nickel aluminide exhibited relatively mild wear at 650° C, displaying less severe surface damage than the nickel. Work on identifying key friction and wear mechanisms and on evaluating the temperature limitations for future applications will continue.

scholarly journals Tribological Behavior of Si3N4/Ti3SiC2Contacts Lubricated by Lithium-Based Ionic Liquids

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Haizhong Wang ◽  
Zenghong Song ◽  
Dan Qiao ◽  
Dapeng Feng ◽  
Jinjun Lu
Keyword(s):  
Ionic Liquids ◽  
Elevated Temperature ◽  
Tribological Properties ◽  
Friction And Wear ◽  
Room Temperature ◽  
Tribological Behavior ◽  
Tribological Performance ◽  
Experimental Conditions ◽  
Thermal Stabilities ◽  
Protective Films

The tribological performance of Si3N4ball sliding against Ti3SiC2disc lubricated by lithium-based ionic liquids (ILs) was investigated using an Optimol SRV-IV oscillating reciprocating friction and wear tester at room temperature (RT) and elevated temperature (100°C). Glycerol and the conventional imidazolium-based IL 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (L-F106) were used as references under the same experimental conditions. The results show that the lithium-based ILs had higher thermal stabilities than glycerol and lower costs associated with IL preparation than L-F106. The tribotest results show that the lithium-based ILs were effective in reducing the friction and wear of Si3N4/Ti3SiC2contacts. [Li(urea)]TFSI even produced better tribological properties than glycerol and L-F106 both at RT and 100°C. The SEM/EDS and XPS results reveal that the excellent tribological endurance of Si3N4/Ti3SiC2contacts lubricated by lithium-based ILs was mainly attributed to the formation of surface protective films composed of various tribochemical products.

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