Abrasive wear of Cemented Granular Composites: Experiments and Numerical Simulations

2017 ◽

Vol 231 (8) ◽

pp. 1078-1088

Author(s):

Zhang Yong ◽

Qi Bo ◽

Sun Xinxin

Keyword(s):

Abrasive Wear ◽

Numerical Simulations ◽

Ceramic Coating ◽

Ceramic Technology ◽

Extreme Conditions ◽

Cold Welding ◽

Seal Failure ◽

Sealing Performance ◽

Different Types ◽

Pipe Joints

Spherical pipe joints are prone to cold welding and wear, which may lead to seal failure under extreme conditions. To solve this problem, the application of ceramic technology in the spherical pipe joints is discussed in this paper. Both numerical simulations and experiments were performed for different types of coating material and different coating thicknesses. The results have demonstrated that the application of a ceramic coating could improve the sealing performance of spherical pipe joints. However, the performance was even better when a fully ceramic cone was used instead. Under the same initial torque, the number of usage cycles was much higher for the fully ceramic cone than for the coated cone, and abrasive wear was very slight. The results are expected to serve as reference for improving the sealing performance of spherical pipe joints.

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Direct Numerical Simulations of Gas–Liquid Multiphase Flows

10.1017/cbo9780511975264 ◽

2001 ◽

Cited By ~ 151

Author(s):

Grétar Tryggvason ◽

Ruben Scardovelli ◽

Stéphane Zaleski

Keyword(s):

Numerical Simulations ◽

Multiphase Flows ◽

Direct Numerical Simulations

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Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038023 ◽

2020 ◽

Vol 640 ◽

pp. A53

Author(s):

L. Löhnert ◽

S. Krätschmer ◽

A. G. Peeters

Keyword(s):

Growth Rate ◽

Numerical Simulations ◽

Accretion Disks ◽

Gravitational Instability ◽

Turbulent Viscosity ◽

Radial Distance ◽

Maximum Growth ◽

Wave Number ◽

Radiative Cooling ◽

Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

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Abrasive wear of polymer/steel gear drives

Progress in Agricultural Engineering Sciences ◽

10.1556/progress.4.2008.1 ◽

2008 ◽

Vol 4 (1) ◽

pp. 1-26

Author(s):

Gábor Kalácska

Keyword(s):

Wear Resistance ◽

Abrasive Wear ◽

Material Selection ◽

Solid Particles ◽

Soil Types ◽

General View ◽

Modern Engineering ◽

Clean Environment ◽

Engineering Polymers ◽

Plastic Gears

Research was performed on the friction, wear and efficiency of plastic gears made of modern engineering polymers and their composites both in a clean environment (adhesive sliding surfaces) and in an environment contaminated with solid particles and dust (abrasive), with no lubrication at all. The purpose is to give a general view about the results of abrasive wear tests including seven soil types as abrasive media. At the first stage of the research silicious sand was applied between the meshing gears and the wear of plastic and steel gears was evaluated and analyzed from the point of different material properties (elongation at break, hardness, yield stress, modulus of elasticity) and its combinations. The different correlations between the experienced wear and material features are also introduced. At the second stage of the project the abrasive sand was replaced with different physical soil types. The abrasive wear of gears is plotted in the function of soil types. The results highlight on the considerable role of physical soil types on abrasive wear resistance and the conclusions contain the detailed wear resistance. The results offer a new tribology database for the operation and maintenance of agricultural machines with the opportunity of a better material selection according to the dominant soil type. This can finally result longer lifetime and higher reliability of wearing plastic/steel parts.

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Vanadium Additions to a High-Cr White Iron and its Effects on the Abrasive Wear Behavior.

MRS Advances ◽

10.1557/adv.2020.414 ◽

2020 ◽

Vol 5 (59-60) ◽

pp. 3077-3089

Author(s):

Alexeis Sánchez ◽

Arnoldo Bedolla-Jacuinde ◽

Francisco V. Guerra ◽

I. Mejía

Keyword(s):

Heat Treatment ◽

Abrasive Wear ◽

Volume Fraction ◽

Wear Behavior ◽

Wear Behaviour ◽

White Iron ◽

Heat Treated ◽

Bulk Hardness ◽

Abrasive Wear Behavior ◽

Vanadium Carbides

AbstractFrom the present study, vanadium additions up to 6.4% were added to a 14%Cr-3%C white iron, and the effect on the microstructure, hardness and abrasive wear were analysed. The experimental irons were melted in an open induction furnace and cast into sand moulds to obtain bars of 18, 25, and 37 mm thickness. The alloys were characterized by optical and electronic microscopy, and X-ray diffraction. Bulk hardness was measured in the as-cast conditions and after a destabilization heat treatment at 900°C for 45 min. Abrasive wear resistance tests were undertaken for the different irons according to the ASTM G65 standard in both as-cast and heat-treated conditions under a load of 60 N for 1500 m. The results show that, vanadium additions caused a decrease in the carbon content in the alloy and that some carbon is also consumed by forming primary vanadium carbides; thus, decreasing the eutectic M7C3 carbide volume fraction (CVF) from 30% for the base iron to 20% for the iron with 6.4%V;but overall CVF content (M7C3 + VC) is constant at 30%. Wear behaviour was better for the heat-treated alloys and mainly for the 6.4%V iron. Such a behaviour is discussed in terms of the CVF, the amount of vanadium carbides, the amount of martensite/austenite in matrix and the amount of secondary carbides precipitated during the destabilization heat treatment.

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