The erosion characteristics of gunmetal have been evaluated practically at different operating conditions. Asymmetrical silica sand (SiO<sub>2</sub>) is taken into account as erodent within range of 300–600 <i>μ</i>m. The impact velocity within 30–50 m/sec, impact angle 15–900, and stand off distance 15–25 mm are inspected as other relevant operating test conditions. The maximum level of erosion is obtained at impact angle 15° which indicates the ductile manner of the tested gunmetal. The higher the impact velocity, the higher the erosion rate as almost linear fashion is observed. Mass loss of gunmetal reduces with the increase of stand-off distance. A dimensional analysis, erosion efficiency (<i>η</i>), and relationship between friction and erosion indicate the prominent correlation. The test results are designated using Taguchi’s and ANOVA concept. <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-2.18977pt" id="M1" height="11.4781pt" version="1.1" viewBox="-0.0498162 -9.28833 23.0523 11.4781" width="23.0523pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><path id="g50-84" d="M463 633C453 636 427 644 417 648C388 660 349 667 316 667C183 667 100 592 100 483C100 398 176 335 223 305L259 282C321 242 358 203 358 149C358 66 301 22 234 22C110 22 70 131 57 208L24 205L28 48C51 23 128 -17 215 -17C342 -17 446 60 446 174C446 262 394 310 317 361L284 383C229 420 183 455 183 515C183 569 222 628 298 628C384 628 418 563 428 481L461 487C459 527 458 593 463 633Z"/></g><g transform="matrix(.013,0,0,-0.013,6.214,0)"><path id="g50-48" d="M381 704H317L48 -163H112L381 704Z"/></g><g transform="matrix(.013,0,0,-0.013,11.796,0)"><path id="g50-79" d="M870 650H622L613 619C694 615 708 606 708 559C708 531 702 477 686 396L636 136H633L281 650H127L120 619C180 616 198 611 212 592C227 572 232 558 220 503L166 254C148 169 139 131 126 89C112 43 85 35 33 32L24 0H280L286 32C208 37 189 44 189 93C189 124 198 179 212 250L267 526H271L622 -8H655L732 396C747 477 762 532 770 556C785 600 798 616 862 619L870 650Z"/></g></svg> ratio indicates that there are 1.72% deviations that are estimated between predicted and experimental results. To elaborately analyze the results, ANN and GMDH methods are mentioned. After erosion process of tested composite, the damage propagation on surfaces is examined using SEM for the confirmation of possible nature of wear behavior. The elemental composition of eroded test samples at varying percentage of gunmetal is analyzed by EDX analysis.

Mohammad Asaduzzaman Chowdhury

Uttam Kumar Debnath

Dewan Muhammad Nuruzzaman

Md. Monirul Islam

Experimental Evaluation of Erosion of Gunmetal under Asymmetrical Shaped Sand Particle

A Ni-based alloy/nano-h-BN self-lubricating composite coating was produced on medium carbon steel by high velocity oxygen fuel (HVOF) spraying technique. The powder feedstocks for HVOF spraying were prepared by ball milling and agglomerated the nano-h-BN with Ni-based alloy powders. The microstructure and mechanical properties of coatings have been investigated. With the increasing of h-BN contents, some delaminations appeared gradually in the coatings and a continuous network with h-BN phase embedded formed in the metallic matrix. The average microhardness of the self-lubricating coating was a little lower for the addition of soft solid lubricant. The friction coefficient of coatings is in the ranges of 0.38&#x2013;0.48 and 0.38&#x2013;0.52 at ambient temperature and 400&#xb0;C, respectively. The maximum bonding strength of coatings reached 23.83&#x2009;MPa.

Xiaofeng Zhang

Long Zhang

Zhenyi Huang

Microstructure Characteristics and Properties of HVOF Sprayed Ni-Based Alloy Nano-h-BN Self-Lubricating Composite Coatings

This work aims to study the wear characterization of common types of acetal polymer gears (spur, helical, bevel, and worm) using a new TS universal test rig, in order to obtain reliable results and as a reference when compared with acetal nanocomposite gears later. The TS universal test rig consists of three different units that are connected by a main driver shaft and a pair of constantly meshing metal spur gears, which transfer power to the bevel and worm test units. The first unit is used to test the bevel gears, the second unit is used to test the spur and helical gears, and the third unit is used to test the worm gears. The loading mechanism is similarly designed to block the brake mechanism. Hobbing and milling machines were used to machine an injection-moulded polymer flanges and produce the tested gears. All gear pairs, except the worm gear, have identical gear ratios. The experiments were performed at speed 1420&#x2009;rpm and the torque was 4&#x2009;Nm. The results showed that the wear rates (in the form of weight loss) of spur gears were consistent with the previous results and the other gear types had larger wear rates.

Samy Yousef

T. A. Osman

M. Khattab

Ahmed A. Bahr

Ahmed M. Youssef

A New Design of the Universal Test Rig to Measure the Wear Characterizations of Polymer Acetal Gears (Spur, Helical, Bevel, and Worm)

Two-lobe pressure dam bearings are commonly used in high speed rotating machineries. Their use is considered more stable than plain cylindrical bearings. Such bearings have a dam in the upper half whereas the lower half is provided with a relief track. Performance of two-lobe pressure dam bearings under micropolar fluid is evaluated. Finite element method is used to solve the modified Reynolds equation. Fluid film pressures are obtained by solving modified Reynolds equation. Thus pressure obtained is used to find performance characteristics of this bearing. The dynamic performance characteristics are studied at various <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-2.2392pt" id="M2" height="11.9171pt" version="1.1" viewBox="-0.0498162 -9.6779 23.6394 11.9171" width="23.6394pt"><g transform="matrix(.0135,0,0,-0.0135,0,0)"><use xlink:href="#g113-77"/></g><g transform="matrix(.0135,0,0,-0.0135,7.488,0)"><use xlink:href="#g113-48"/></g><g transform="matrix(.0135,0,0,-0.0135,13.075,0)"><use xlink:href="#g113-69"/></g></svg> ratios. Three <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-2.2392pt" id="M3" height="11.9171pt" version="1.1" viewBox="-0.0498162 -9.6779 23.6394 11.9171" width="23.6394pt"><g transform="matrix(.0135,0,0,-0.0135,0,0)"><use xlink:href="#g113-77"/></g><g transform="matrix(.0135,0,0,-0.0135,7.488,0)"><use xlink:href="#g113-48"/></g><g transform="matrix(.0135,0,0,-0.0135,13.075,0)"><use xlink:href="#g113-69"/></g></svg> ratios are considered 1.6, 2.0, and 2.4 for the analysis purpose. Results obtained are presented for various micropolar parameters. Results show that stability of two-lobe pressure dam bearings increases with decrease in aspect ratio (<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-2.2392pt" id="M4" height="11.9171pt" version="1.1" viewBox="-0.0498162 -9.6779 23.6394 11.9171" width="23.6394pt"><g transform="matrix(.0135,0,0,-0.0135,0,0)"><use xlink:href="#g113-77"/></g><g transform="matrix(.0135,0,0,-0.0135,7.488,0)"><use xlink:href="#g113-48"/></g><g transform="matrix(.0135,0,0,-0.0135,13.075,0)"><use xlink:href="#g113-69"/></g></svg>).

Sanyam Sharma

C. M. Krishna

Effect of <svg  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-2.2392pt" height="11.9171pt" version="1.1" viewBox="-0.0498162 -9.6779 23.6394 11.9171" width="23.6394pt"><g transform="matrix(.0135,0,0,-0.0135,0,0)"><path id="g113-77" d="M541 160L512 170C485 116 462 88 439 67C411 41 376 35 318 35C272 35 238 37 224 48C207 61 205 85 212 121L290 533C305 611 308 615 391 622L397 650H139L133 622C217 615 221 612 206 533L126 118C111 41 103 34 23 26L17 0H474C489 31 528 124 541 160Z" /><glyph.data ascent="3473" descent="-2876" horiz-adv-x="553" vert-adv-y="553" /></g><g transform="matrix(.0135,0,0,-0.0135,7.488,0)"><path id="g113-48" d="M368 703H309L44 -163H104L368 703Z" /><glyph.data ascent="3473" descent="-2876" horiz-adv-x="412" vert-adv-y="412" /></g><g transform="matrix(.0135,0,0,-0.0135,13.075,0)"><path id="g113-69" d="M743 375C743 570 607 650 407 650H136L130 622C214 612 220 606 204 526L125 122C110 43 105 36 24 27L17 0H250C382 0 482 23 571 76C680 141 743 248 743 375ZM644 379C644 188 520 36 305 36C277 36 249 38 229 46C205 55 202 71 212 126L293 553C300 588 306 600 317 606C330 613 356 617 390 617C547 617 644 537 644 379Z" /><glyph.data ascent="3473" descent="-2876" horiz-adv-x="766" vert-adv-y="766" /></g></svg> Ratio on the Performance of Two-Lobe Pressure Dam Bearing: Micropolar Lubricated

The problem of couple stress squeeze films considering viscosity pressure dependence (VPD) has been analysed in a curved circular geometry. Using Stokes microcontinuum theory and the Barus formula, the Reynolds type equation has been derived. The approximate analytical expressions for the squeeze film pressure and load carrying capacity are obtained using a perturbation technique. The numerical solutions for the squeeze film pressure and load carrying capacity are presented for the sinusoidal motion of the upper curved disk, assuming an exponential form for the curvature. The effects of curvature, the non-Newtonian couple stresses, and VPD and their combined effects are investigated through the squeeze film pressure and the load carrying capacity of the squeeze film.

Vimala Ponnuswamy

Sumathi Govindaraj

Couple Stress Squeeze Films with VPD in a Curved Circular Geometry

The combined effect of surface roughness and magnetic field on the performance characteristic of the circular plates lubricated with conducting couplestress fluid (CCSF) has been studied. On the basis of the Christensen Stochastic model, the generalized stochastic Reynold&#x2019;s equation is derived. Modified equations for the nondimensional pressure, load load-carrying capacity, and squeeze film time are derived. The results are presented both numerically and graphically and compared with conducting smooth surface case. It is observed that the surface roughness effects are more pronounced for couplestresses as compared to nonconducting Newtonian fluid (NCNF) in the presence of magnetic field.

Syeda Tasneem Fathima

N. B. Naduvinamani

J. Santhosh Kumar

B. N. Hanumagowda

Effect of Surface Roughness on the Squeeze Film Characteristics of Circular Plates in the Presence of Conducting Couplestress Fluid and Transverse Magnetic Field

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<p><em>Advances in Tribology</em> publishes papers on the science of friction, wear, and lubrication. Topics covered include investigations into contact mechanics, wear and damage processes, surface and coating engineering, and lubrication technology.</p>


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Advances in Tribology - Table of contents 2015

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Advances in Tribology publishes papers on the science of friction, wear, and lubrication. Topics covered include investigations into contact mechanics, wear and damage processes, surface and coating engineering, and lubrication technology.

Advances in Tribology