Mehdi Mortazavi and Michael Nosonovsky

Abstract Adhesive properties of polymeric materials and modern techniques of surface modification make polymers appropriate for Green Tribology applications, which require functional surfaces and the ability to control, and modify and surface properties, such as adhesion and wetting. Polymers, along with polymer composites, are appropriate materials for coating and various biomimetic applications, such as those utilizing the Lotus and gecko effects. In this chapter, we review polymer properties...

O o C o

Fig. 16.1 Scanning electron micrograph of a Precipitatory fly ash (left), b Cenosphere fly ash (right) 20 Fig. 16.1 Scanning electron micrograph of a Precipitatory fly ash (left), b Cenosphere fly ash (right) 20 Fig. 16.2 Optical micrograph of a typical polyester cenosphere composite containing 29.5 fly ash 21 ash can improve various properties of matrix materials including stiffness, strength, and wear resistance. Cenosphere fly ash, which consists of hollow fly ash particles, can be used for...

Self Lubricating Behavior of Silver Graphite Composites

Several metal matrix composites have been designed for use in electrical contacts by combining constituents which impart excellent wear resistance with constituents which have high electrical conductivity. Apart from copper base-graphite composites, another composite which is widely used in this field include silver base-graphite composites. The friction and wear behavior under sliding in the Fig. 17.21 Variation of wear loss with sliding distance as function of a normal load, and b current 47...

Wind Turbine Theory and Designs

The term wind turbine power systems (WTPS) denotes systems that extract kinetic energy from wind and convert it into usable electrical energy. Along these lines, the size and mechanical complexity of wind turbines can range from relatively small (e.g., household wind turbines) to large, offshore wind turbines. Regardless of the size, all wind turbines incorporate airfoil blades that are pitched into and pushed by the wind, causing rotational power that is ultimately transferred to a generator....

Yaw Bearing

The yaw mechanism rotates the nacelle about its vertical axis to keep the rotors oriented into the wind. Ideally, yaw bearings should provide smooth rotation and long service life as well as yaw damping to prevent unwanted yaw oscillations. Most turbines thus employ roller bearings or ball bearings in their yaw drives, although recent interest has been directed towards gliding bearings that use low-friction synthetic sliding elements in place of balls or rollers. Ball bearing configurations are...

Fly Ash Based Composites for Friction Braking Application

Malhotra et al. 28 studied the effect of fly ash and bottom ash on the frictional behavior of a base composite matrix consisting of phenolic resin, slag fiber, and scrubber sludge. Table 16.3 shows the various fractions used to form friction composite. Figure 16.4 shows the variation of friction coefficient with time for basic matrix composite and commercial automotive brake pads. It can be seen that the commercial brake composite showed a stabilized friction value of around 0.3. However, this...

Epoxidation

Epoxidation is a chemical reaction in which an oxygen atom is joined to an olefinically unsaturated molecule to form cyclic, three-membered ether (Fig. 11.2). The products of epoxidation are known as oxirane compounds or epoxides. In the case of vegetable oils the double bonds present in the unsaturated fatty acids of triglyceride structure are potential sites for chemical modifications and can be epoxidized with hydrogen peroxide, either in acetic acid or formic acid to give epoxidized...

Recommended Oil Particle Filters

A detailed model of a wind turbine contamination control system is shown in Fig. 18.30. When available, full-flow filters rated at b5(c) C 1,000 are recommended. As shown in Fig. 18.31, bearing life can be extended 2-5 times simply by installing 5 im full-flow gear oil filters in place of the older, less-efficient 1025 im filters found in some wind turbine gearboxes. In addition, wear debris released by gear teeth, bushings, and some dynamic seals are diminished in clean oil maintained by 5 im...

Fatigue Life Prediction for Pitch and Yaw Bearings

Because pitch and yaw bearings exhibit oscillatory motion and do not spin continuously, the life estimation theory of Lundberg and Palmgren (Eq. 18.7), which predicts lifetime in terms of number of rolling cycles to probable failure, is not directly applicable. However, studies have shown that the Lundberg-almgren estimation can be modified to apply to oscillating bearings based upon the critical angle of oscillation hcrit, which is calculated as where Z is the total number of rolling elements...

Mechanical Brake

Modern wind turbines incorporate a mechanical brake on the high-speed section of the drivetrain, normally between the gearbox and the generator. This mechanical brake, which almost always is in the form of a disk brake, is primarily responsible for locking down the rotor during shutdown such that servicing and repair work can take place. Beyond functioning as a parking brake, some turbines employ the mechanical brake as a secondary braking system to complement aerodynamic braking during...

Multi Effect Distillation

Similar to MSF, multi-effect distillation (MED) involves a series of stages of successively decreasing temperature and pressure. From a thermodynamic standpoint, it is more efficient than MSF, however, performance of MED processes are directly proportional to the number of effects used. MED plants typically use an external steam supply at a temperature of around 70 C. Small capacity MED plants were used since the early 1900s for water desalination onboard ships, whereas the first land-based MED...

Qualitative Studies

The earlier works on self-organization are characterized by qualitative, rather than quantitative analysis of self-organization mechanisms. For example, it is noted in many publications that typical tribosystems possess the qualities which, according to Prigogine, are required (but not sufficient) for the self-organization, for example, the system should be thermodynamically open, nonlinear, and it should operate far from the equilibrium. Bershadsky 8 suggested a classification of various...

Effect of Surface Wettability

Next, the effects of surface wettability on the cell behaviors in growth and adhesion were studied by testing neonatal rat cardiac fibroblasts on Nanopillar samples of varying structural aspect ratios in both hydrophilic and hydrophobic surface conditions. Figures 4.9, 4.10, 4.11, 4.12 show the results of microscopy. Figure 4.9 shows the SEM images of neonatal rat cardiac fibroblasts cultured on hydrophilic samples for 2 days to 8 weeks. In 2 days, cells on Smooth Smooth Nanopillar-Low...

Surface Initiated Fatigue Spalling

The dynamic clearances between moving parts are on the order of 1 im, which is the same dimension as many hard contaminant particles. Hard particles trapped in rolling contacts indent raceway surfaces creating raised metal shoulders that act as stress risers 85-88 . The pressure increase around a dent can surpass the normal Hertzian pressure. During subsequent rolling cycles, tangential surface stress plus lubricant forced into the cracks cause the cracks to propagate beneath the surface....

K R Sathwik Chatra N H Jayadas and Satish V Kailas

Lubricants and lubrication were inherent in a machine ever since man invented machines. It was water and natural esters like vegetable oils and animal fats that were used during the early era of machines. During the late 1800s, the development of the petrochemical industry put aside the application of natural lubricants for reasons including its stability and economics. The growing awareness of the lower biodegradability and higher toxicity of petrochemical-based lubricants created the...

Wind Turbine Design and Performance

Downwind Hawt

Wind turbines are generally classified into two categories horizontal-axis wind turbines (HAWTs) and vertical-axis wind turbines (VAWTs). VAWTs incorporate a vertically oriented rotor shaft, with drivetrain components located at their base. Early VAWT designs include Savonius, Darrieus, and Giromill, or H-bar designs (Fig. 18.3). Although VAWTs have shown to have advantages over HAWTs in that they are omnidirectional and their drivetrain components easily maintained, their installation heights...

Hydrogenation

Hydrogenation changes liquid oil made of triglycerides of polyunsaturated fatty acids to one containing mostly monounsaturated fatty acids. This procedure improves the functionality and flavor stability of the oil. Hydrogenation of vegetable oils increases the stability and improves the shelf life of oils 68 . In the industry the predominantly used catalysts are heterogeneous catalysts such as carrier catalysts (palladium on activated carbon), skeleton catalysts (Raney nickel) or metal oxide...

Sliding Velocity

With increasing sliding velocity the coefficient of friction decreases. This was first reported in 1953 by Bowden 53 . Evans et al. 44 , who were the pioneers in modeling ice friction mathematically, confirmed these findings both experimentally and theoretically. Many other researchers found the same dependency using different experimental setups and materials 46, 48, 51, 54-56 . Figure 9.8 illustrates some of these results. The higher the sliding velocity the more the frictional heat produced....

Electrospinning

Multi Jet Electrospinning

Electrospinning is a process in which a high electrical field is used to fabricate fibers with diameters ranging from a few nanometers to tens of micrometers from liquid polymeric solutions. A composition of solvents can be used as well. The process is suitable for a wide variety of polymers and can be conducted at room temperature. The morphology, surface texture, and wetting properties of the fabricated fibrous mat can be controlled by changing the solution characteristics or electrospinning...

Experimental Study of WEC Device Efficiency

Patel's initial wave energy machine is a buoy that floats on top of the wave as it passes underneath. The buoy is set up in a 'teeter-totter' fashion, having the buoyant part on the leading edge of the pivot. This buoy has large arches attached over the platform, which rotate above and below an overhead shaft, creating a rotating motion. The linearization of the crankshaft movement is attained through a series of clutch bearing installed in dowels on the shaft. These...

Contact Mechanics and Adhesion

When two bodies come into contact the interacting forces across the contact boundary result in adhesion force which is the combination of different Fig. 8.5 The schematic of a sphere of radius R attached to a rigid flat surface contributions (Van der Waals force, electrostatic force, capillary force, and others). This adhesion force depends on different parameters such as the number of contributing forces, the strength of the contributing forces, area of contact between two bodies, the...

Wetting States

Where y, ySL, ySA are the surface tensions at the liquid air (vapor), solid liquid, and solid air interfaces, respectively. The contact angle of a droplet deposited on a solid depends on external parameters, such as temperature. The temperature change may stimulate the transition from the partial to complete wetting of a solid substrate. In this case we observe a wetting transition on a smooth solid surface The Young equation supplies the sole value of contact angle for a certain combination of...

Additive Drop Out

Another form of oil degradation is additive drop-out. Some gear oil additives have strong affinity for water (hydrophilic polar additive molecules). They become unavailable by congregating in and around water droplets. Furthermore, high concentrations of dissolved water can break colloidal suspensions of finely divided powders sometimes used as anti-wear additives, resulting in dumping of massive amounts of material. Not only are these additives inactivated by water, but as illustrated in Fig....

Molding by Using Silicon Templates

Patterned silicon wafer is also a suitable candidate for micro- and nano- fabrication of polymeric surfaces. However, since silicon wafer is expensive and fragile it has been used to make intermediate polymer molds which are more flexible and can be used many times. Jeong et al. 37 fabricated polymeric molds by photolithography on silicon masters. The prepared molds were then used to fabricate micro- and nanoscale roughness on a UV-curable resin by capillary molding technique. Capillary molding...

Bearing Dynamics and Wear

Micropitting Bearing

The dynamics of rolling element bearings can be idealized as that of two non-conforming solids which initially touch along a point or a line. Under a compressive load in static conditions, the surfaces deform, causing a contact region of rectangular, ellipsoidal, or spherical shape depending on the geometry of the contacting bodies. Contact of this nature can be analyzed according to Hertzian contact theory 33 . Studies have shown that the contact pressure distribution is maximum in the...

Vegetable Oils as Bioderived Lubricants Its Properties and Applications

Vegetable oils are mainly classified into two categories 1. Edible vegetable oils These oils are produced in large amounts worldwide and are mainly used for edible purposes. Examples of edible oils include coconut oil, palm oil, sunflower oil, corn oil, cottonseed oil, mustard oil, peanut groundnut oil, olive oil, sesame oil, safflower oil, rice bran oil, babassu oil, soybean oil etc. 2. Non-Edible oils These oils are mainly used for commercial purposes than for edible purpose. The commonly...

Mechanism of Alkali Catalyzed Transesterification

The first step involves the attack of the alkoxide ion to the carbonyl carbon of the triglyceride molecule, which results in the formation of a tetrahedral intermediate. The reaction of this intermediate with an alcohol produces the alkoxide ion in the second step. In the last step the rearrangement of the tetrahedral intermediate gives rise to an ester and a diglyceride. The mechanism of alkali catalysed transesteri-fication reaction is given in Fig. 11.12. The transesterification process can...

Power Control

Active Stall

Ideally, a wind turbine should be able to extract as much power as possible up to the rated power of the generator, then limit the extracted power to the rated level as the wind speed increases further. Modern wind turbines are able to maintain the desired amount of power, in part, by controlling the pitch of the rotor blades. Rotor pitch control can take place using one of the following methods Fig. 18.6 Power characteristics of fixed-speed wind turbines under a stall control, b active stall...

Tribological Behavior of Sisal Fiber Reinforced Resin Brake Composites

In automotive industry, non-asbestos fiber-based components such as brake pads and lining couplings, etc. have been in demand due to environmental and human health concerns. The alternatives to asbestos fibers include mineral fiber, metal fiber and artificial polymer fibers such as glass fiber, alumina fiber, carbon fiber, steel fiber, Fig. 12.1 Variation in friction coefficient and wear rate with sisal fiber content 16 Fig. 12.1 Variation in friction coefficient and wear rate with sisal fiber...

Thermal Vapor Compression

F35 Power Thermal Management System

As mentioned above, MVC systems mechanically compress vapor (which is later used for evaporation of saline), whereas TVC systems thermally compress vapor utilizing a steam jet compressor. The main problems associated with the TVC process are 31 1. Vapor generated in the chamber may contain some solute molecules which lead to corrosion of compressor blades and other components when drawn into the compressor. Fig. 19.9 (Left) A schematic diagram of a Thermal Vapor Compression system 32 , with the...

Modelling and Analysis Using Computational Fluid Dynamics

Extensive research has been conducted in the area of journal bearings over many years for various operating conditions and geometry, effects of different types of lubricants (oil and water), different numbers (zero, one and three) and positions of the grooves and flow of lubricants between shaft and bearing. To minimize the experimental time and cost of predicting the performance of the journal bearing operating under wide variety of conditions has led to the development of clearance volume of...

Lubricants 1431 Introduction

A lubricant is a substance (often a liquid) introduced between two moving surfaces to reduce the friction between them, improving efficiency and reducing wear. It may also have the function of dissolving or transporting foreign particles and of distributing heat. Most lubricants currently originate from petroleum base stocks that are toxic to the environment, making it increasingly difficult for safe and easy disposal. It is claimed that 50 of all lubricants sold worldwide end up in the...

Wind Turbine Tribological Components and Analysis

The tribological components in a wind turbine include rotor support bearings, intermediate gearbox rotor bearings, high-speed bearings, pitch bearings in the hub, epicyclic and parallel gears in the gearbox, a mechanical brake, a roller bearing system in the yaw mechanism, and slip rings in generator (if the generator is a doubly fed induction generator). Rolling-element bearings are incorporated to support the rotor and rotor shaft, the gearbox shafts, and the generator input shaft, with the...

Prospective Research

Based on the above review on the literatures, it can be seen that the efficient way to improve the physical properties of oil-based lubricants is to alter the chemical structure of the substances. Particularly, high degree of branching can lower viscosity index, whereas high linearity can lead to high viscosity index, and relatively poor low-temperature characteristics. In contrast, low saturation can limit oxidation stability, whereas high saturation can result in outstanding oxidation...

Waxes 1411 Introduction

The term wax is used to denote linear or branched-chain of hydrocarbon (up to about C40H82) mixed with organic and inorganic material 1 . From the applied perspective, waxes are defined as mixtures of lipophilic compounds that are solid at room temperature, range from transparent to opaque, and are ductile and easy to polish 2 . Waxes are used as additives into lubricants, adhesives, coatings, sealants, impregnation materials and adjuvants, etc. A wide range of commercial products rely on...

Introduction

Drawing Water Desalination Plants

According to the 2010 UN-Water Global Annual Assessment of Sanitation and Drinking-Water 1 , around 1.1 billion people in developing countries have inadequate access to water, while 2.6 billion lack basic sanitation. Close to half of T. G. Hurd S. Beyhaghi M. Nosonovsky (& ) Department of Mechanical Engineering, College of Engineering and Applied Science, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA e-mail nosonovs uwm.edu M. Nosonovsky and B. Bhushan (eds.), Green Tribology,...

Fly Ash Material and Characteristics

Fly ash is one of the residues created during the combustion of coal in coal-fired power plants and comprises fine particles that rise with the flue gases. In the past, fly ash produced from coal combustion was simply entrained in flue gases and Table 16.2 Historical compositions of automotive friction brake materials 1 Table 16.2 Historical compositions of automotive friction brake materials 1 Hair or cotton belting (limited by charring Molded limings with shorter chrysotile fibers, brass...

Surface Structure

While the concepts of roughness and surface structure are closely related, we distinguish between the two here, reasoning that roughness is of a more random nature than a specific structure or pattern. Itagaki et al. 43 found in their experiments that their samples with polished grooves in sliding direction showed similar low friction as highly polished sliders. Kietzig et al. 60 recently examined the influence of surface structure more closely and found that for the same roughness value Ra of...

Contamination Effects

Gear oil recirculates through wind turbine gearboxes, lubricating mating surfaces and removing heat. Unfortunately, contaminant particles suspended in the gear oil, as well as water in the parts per million (ppm) range, can significantly degrade the performance and reliability of gearboxes. Sources of contaminant particles include cutting and grinding swarf built-in from manufacturing, ingression of airborne abrasives through vents and mechanical seals, and internally generated wear debris and...

References

Anonymous, GLAAS 2010 UN-Water global annual assessment of sanitation and drinking-water (2010a), Accessed 16 May 2011 2. Anonymous, The 3rd United Nations world water development report water in a changing world (2009), Accessed 16 May 2011 3. Anonymous, United Nation news center (2011a), http www.un.org apps news story.asp NewsID 38253& Cr Population. Accessed 16 May 2011 4. K. Wangnick, IDA Worldwide Desalting Plants Inventory. Report No. 18. Wangnick Consulting, Gnarrenburg (2004) 5. K....

Self Lubricating Behavior of Magnesium Graphite Composites

Like aluminum, magnesium alloys have been used in automobile and aerospace industries due to their low density, high specific strength and stiffness, good damping characteristic, excellent machineability and castability. However, its corrosion and wear resistance limit it to be used as widely as aluminum alloy. The most commonly used magnesium alloy is AZ91 alloy. Attempts have been made to study the tribological performance of magnesiumgraphite composites. Qi 24 studied the influence of...

Self Lubricating Behavior of Copper Graphite Composites

Copper metal matrix composites reinforced with particulate graphite are the potential candidate materials for electrical sliding contact application such as brushes in the electric motor and generator 28-35 . In the case of low voltage and high current densities, typically for sliding parts of welding machines, it is required to employ materials with a very high specific electrical conductivity, good thermal conductivity and low friction coefficient. Such conditions are fulfilled only by...

Solution Method

Adjusting the crystallization time and nucleation rate for crystalline polymers, and the aggregation and precipitation rate in case of amorphous polymers have been shown to have a significant effect on the surface roughness of the films fabricated by solution casting method. Temperature and addition of non-solvent are two of the most important factors controlling the precipitation and the final morphology of the cast films. Lu et al. 58 investigated the preparation of low-density polyethylene...

R Pai and D J Hargreaves

Abstract The increasing ecological awareness and stringent requirements for environmental protection have led to the development of water lubricated bearings in many applications where oil was used as the lubricant. The chapter details the theoretical analysis to determine both the static and dynamic characteristics, including the stability (using both the linearised perturbation method and the nonlinear transient analysis) of multiple axial groove water lubricated bearings. Experimental...

Metathesis of Unsaturated Fats and Oils

The metathesis of alkenes is a metal-catalyzed exchange of alkylidenic groups ( CR2). The Greek word metathesis means rearrangement or displacement. This reaction is in principle a reversible reaction. That means that at most a 50 yield is achievable if no procedural intervention occurs. Oleochemical metathesis can be distinguished and divided into different types In self-metathesis (Fig. 11.6), the same fatty substrate reacts with itself, in the cross-metathesis a fatty substrate reacts with...

Biomimetic Surfaces

Biomimetics (also referred to as bionics or biomimicry) is the application of biological methods and systems found in nature to the study and design of engineering systems and modern technology. It is estimated that the 100 largest biomimetic products generated approximately US 1.5 billion over the years 2005-2008 and the annual sales are expected to continue to increase dramatically 14 . Many biological materials have remarkable properties which can hardly be achieved by conventional...

General Model

For a composite interface built of two fractions with the fractional areas off1 and f2 (so that f1 f2 1) the contact angle is given by the Cassie equation cos h f1 cos h1 + f2 cos h2 (7.3) where h1 and h2 are the contact angles of the fractions. If a composite material has a matrix and reinforcement with the volume fractions of fm and fr (so that fm fr 1) forming a rough surface the contact angle is then given by cos h Rfm(1 fr) cos hm + Rfrfr cos hr (7.4) where hm and hr are the contact angles...

The Relation of Green Nano Tribology and Global Challenge 13 Energy

Issue How can growing energy demand be met safely and efficiently The Millennium Projects annually publishes the State of the Future report (with few pages in print and vast information on CD) and has an extensive webpage (http www.millennium-project.org). Concise information about this global challenge as well as the Executive Summary of the 2011 State of the Future report can be accessed online at Challenges chall-13.html and at SOF2011-English.pdf. The following quotations from the...

Review of Literature

Test Litwin

The first designs of these bearings had a plain bore, but this was modified several times in order to improve the operation of the bearing. The most popular design used today is the straight fluted bearing. This design of bearing consists of a number of load-carrying lands or staves, separated by flutes orientated axially in the bearing (See Fig. 13.2). The flutes supply the bearing with lubricant, which enters at one end of the bearing and leaves at the other. The flexible rubber bearing liner...

Plasma Electron and Laser Treatment

Plasma treatment is the process of using an ionized gas to modify the surface properties of various materials. Plasma treatment of polymers changes the chemical and physical properties of the polymeric surface, and can be used to modify the wetting and adhesion properties of polymeric surfaces. Depending on the applied plasma treatment, the resultant surface can be more hydrophobic or more hydrophilic. Kim et al. 43 used an atmospheric methane plasma treatment to fabricate hydrophobic coating...

Jheai nx HXheal

Where L, M, N, H are corresponding Onsager coefficients (Fig. 3.13). The degradation force X is an externally applied thermodynamic force that causes the Fig. 3.13 Block diagram of the healing process. Deterioration is caused by an external force. The deteriorated system is brought out of equilibrium so that the restoring (healing) force is created, which is coupled with the degradation flow through the parameter M 55 degradation. In most self-healing mechanisms the system is placed out of...

Transient Loading

It must also be noted that wind turbines, unlike other forms of electricity production, are designed to generate under a spectrum of power levels 5 , and thus must contend with transient loads within their drivetrains. A commonly used means to estimate the power-producing ability and drivetrain loads is to assume that it operates under a certain wind speed distribution. The distributions that are frequently used are Weibull (Fig. 18.5) and Rayleigh distributions 23, 24 . To determine the number...

Self Lubricating Behavior of Nickel Graphite Composites

Nickel-graphite composites are widely used in the high-efficiency engine due to their excellent high-temperature performance. Considerable efforts have been made to study the effect of various operating parameters on the tribological Fig. 17.24 Variation of friction coefficients and wear rates for different a graphite content, b load, c speed, and d counterpart materials 50 Fig. 17.24 Variation of friction coefficients and wear rates for different a graphite content, b load, c speed, and d...

Rating Particle Filters

The international standard method for rating lube and hydraulic filters is the Multi-Pass Test 95 . As illustrated in Fig. 18.29, a slurry of silica particles is continuously fed into the test circuit. As particles flow into the filter under test, some are captured, and the remainder continues to recirculate. Throughout the Table 18.5 Summary of recommended contamination control practices for wind turbines removal Off-line contaminant removal Drain oil from gears directly back into the sump,...

Ice Friction Models

Figure 9.3 and the above discussion on the isolated effect of the various parameters illustrate that the matter of ice friction includes different competing processes with many interactions. Therefore, it is not surprising that no single conclusive model exists, which describes ice friction across all regimes. Nonetheless, there has been a major effort to model and thereby better understand and predict ice friction. The most interesting models are briefly introduced here. Evans et al. 44...

Drivetrain Layout

Two Opposing Rotor

The nacelle of the wind turbine is the external housing that contains the main mechanical components of the system. As shown in Fig. 18.7, these components include the rotor shaft and bearings, a gearbox assembly (if necessary), a lubricant filtration system, a mechanical braking system, a generator, and power electronics. The gearbox transmits power from the main shaft to a high-speed shaft, which, in turn, drives the generator. The drivetrain components and nacelle cover are mounted onto a...

Gear Dynamics and Wear

Scuffing Gears

The gears in the transmission experience rolling and sliding contact along the gear tooth faces. Contacting gear teeth slide and roll against one another as they come into mesh and then transition into pure rolling contact at the pitch point. As the teeth move out of mesh, the contact mode transitions back to combined rolling and sliding. Fig. 18.22 Gear tooth surfaces with scuffing damage, from 67 In the case of helical gears, it must be noted that an involute helical gear can be analyzed as a...

Modeling CA Hysteresis

Predicting CA hysteresis for a rough surface with a given topography is a difficult task. One approach is a numerical simulation however, in most cases the simulations are limited to two-dimensional (2D) topography. Kusumaatmaja and Yeomans 18 showed that contact angle hysteresis is sensitive to the details of the surface patterning. Despite that, certain conclusions about the relation of the contact angle hysteresis to roughness can be made. It is known that the energy gained for surfaces...

Definition of Contact Angle Youngs Equation

Wetting is the process of making an interface between a solid and a liquid. The primary parameter for a liquid wetting a solid is the angle at which the liquid-vapor interface meets the solid-liquid interface, called the static contact angle h as seen in Fig. 8.6. In this figure, h is the angle between the solid surface and the tangent to the liquid-vapor interface. ySG, ySL, and yLG are solid-vapor, solid-liquid and liquid-vapor interfacial energies respectively. At the equilibrium, Young's...

Effect of Nanotopography

Nanotopography

In order to examine the effects of nanotopography on the behaviors of cell growth and adhesion, human foreskin fibroblasts were first tested on the surface samples of varying patterns and structural aspect ratios, while their surface conditions were all hydrophilic. Figures 4.2, 4.3, 4.4, 4.5, 4.6, 4.7 and 4.8 show the results of microscopy. Fig. 4.1 SEM images of 3D sharp-tip nanostructures 28, 30 . Well-ordered silicon nanostruc-tures (a-c 'Nanopillar', d-f 'Nanograting') covered the surface...

Why Water Lubrication

The use of water as a bearing lubricant dates back to the earliest days of shaft-driven propellers on ships. However, as supply of good quality lignum vitae bearings diminished, ship owners pushed marine engineers for new systems with more predictable wear rates and extended periods between dockings. The result was the development of systems in the 1940s using mineral-oil-lubricated white metal bearings in a sealed stern tube. Bearing wear rates decreased, especially when operating in dirty...

Green Nano Tribology

Si-wei Zhang, past chairman of the Chinese Tribology Institution, coined the term 'Green Tribology' and launched it as an international concept in June 2009. Green tribology is the science and technology of the tribological aspects of ecological balance and of environmental and biological impacts. Its main objectives are the saving of energy and materials and the enhancement of the environment and the quality of life (Peter Jost 2009, 2 ). amoeba red blood cell cholera bacterium tobacco mosaic...

Effect of Cell Type

The dependency of cell behaviors on cell types were also studied by testing three different cells (human foreskin fibroblast, NIH-3T3, and smooth muscle cell) on both Nanopillar and Nanograting samples of a hydrophilic surface condition. Figures 4.13, 4.14, 4.15 show the results of microscopy. For the human foreskin fibroblast, the results shown in Figs. 4.2, 4.4, and 4.5 are presented in Figs. 4.13, 4.14, 4.15 again, respectively, to help the comparison. Figure 4.13 shows the fluorescent...

Power Savings

Data gathered during the trial was captured in weekly intervals due to limitations of the data recorders. There was no limitation on data available for current drawn however occasional glitches resulted in corrupted data from time to time. The result is that to ensure repeatable and consistent results, data was gathered more than once over a six month period. The graphs and tables show the average calculated power consumption for each gearbox for specific weeks during the trial from the graphs...

The Size of the Additive and the Scale Effect on the Lubrication

Mos2 Friction Coefficient

In the literature, considerable effort has been made to study the effect of powder lubricant size (micron-scale, submicron-scale, and nano-scale) on system performance 36-38, 41 . Numerous studies have indicated that sub-micron-particulate additives of graphite, MoS2, and other lamellar solids have improved the performance of base oils 36, 57-59 . Sub-micron forms of these powder lubricants have been synthesized using chemical vapor deposition, liquid precipitation, electronic Fig. 10.8...

Green Boric Acid Powder Lubricant

Efforts are being made to develop and implement powder lubricants that come from natural resources. As reported in the literature, solid lubricants such as boric acid have excellent lubrication properties without requiring expensive disposal 42-45 . Thus, boric acid is another often overlooked lamellar solid that has been found to be an effective green powder lubricant. The effectiveness of boric acid can be attributed to its low friction and shear strength values. As reported in the literature...

Summary and Conclusions

The advantages of axial groove journal bearings with water as a lubricant over less environmentally friendly oil-lubricated bearings are becoming increasingly recognised and understood. In terms of regular use, preventive maintenance and operating costs can be potentially reduced. For example, the oil in lubricating systems has to be replaced at specified intervals. The usage of oil results in sludge deposits and in accordance to preventive maintenance schedule the machine parts have to be...

UWMilwaukee Wave Energy Conversion Device

In this section we will discuss a wave energy collection device developed at the UWM, The machine is a coastline application wave energy machine, which uses a buoy and a rocker arm to change the linear, vertical motion of the wave into mechanical rotational energy. Two models of the machine were built (Fig. 21.2). The earlier model was developed in 2010 by Dr. Patel from Milwaukee (Fig. 21.2a). It used wood frame and bicycle bushing-based ratcheting mechanism, which guaranteed that the output...

Practical Applications of MQL 20441 The Aluminium Value Chain

Mql Machining Applications

Aluminium processing starts at the smelter producing molten aluminium which then goes to the cast house where it is cast in either slab or T-Bar in a horizontal casting machine or in a vertical cast into poles (Fig. 20.1). Our involvement started with mould lubrication of the casting of T-Bar material where lubrication plays an important role when just solidified T-Bar is moved from the mould and where the mould release properties of a lubricant are required to allow a smooth flow of aluminium...

The Concept of Selective Transfer

The concept of the ''selective transfer'' or the ''non-deterioration effect'' was developed by Garkunov 27 . According to his definition, the selective transfer is a type of friction which is characterized by the formation at the contact interface of a thin non-oxidized metallic film with a low shear resistance which is not able to accumulate dislocations. According to the selective transfer scheme, a selective dissolution of a component of a copper alloy occurs, followed by the transfer of the...

Pitch and Yaw Bearings

Blade pitching systems are used to control power and rotor speed, while yaw systems are used to orient the rotor perpendicular to the wind direction. The bearings that are used for pitch and yaw systems are often discussed within a similar context, as their ranges of motion and wear modes are often similar to one another. Additionally, both pitch and yaw bearings experience similar types of loading namely, an eccentrically applied thrust, which can be divided into a pure axial load and an...

Other Methods of Desalination

In addition to the thermal and membrane methods of desalination, there are also other methods that have been recently suggested. Among these include freezing desalination and various types of renewable energy-based desalination, such as solar desalination and geothermal desalination 19, 23, 39, 40 . When seawater freezes, salts initially tend to freeze with the water. However, due to mass transport in the semisolid layer the salinity throughout the layer decreases with time. As a result,...

Energy Barrier and Cassie Wenzel and Young Contact Angles

It is well established experimentally that wetting transitions are usually irreversible. This conveys the suggestion that some general reasons for such irreversibility exist. It turns out that a variety of wetting states, as well as transitions between them, may be described on the same mathematical basis that gives the possibility to elucidate their features which are independent of peculiarities of a particular substrate. Starting with the spherical model for the droplet shape, it can be...

Heterogeneous Surfaces Cassie Baxter Model

The alternative method for the heterogeneous surfaces is that of Cassie-Baxter model 10 . When the surface is composed of two different materials, the surface has a surface area fraction f1 with a contact angle h1 and a surface area fraction f2 with a contact angle 02. The contact angle for the heterogeneous interface can be expressed by the following equation cos 0 f1 cos h1 + f2 cos 02 (8.11) In the Cassie-Baxter model the liquid droplet sits on a composite surface made of solid f1 fSL) and...

Molding by Using Anodic Aluminum Oxide Templates

Anodic Aluminum Oxide (AAO) is a self-ordered nanostructureed material formed on aluminum surface from an electrochemical oxidation in acidic solutions. AAO is composed of uniform nanosized vertical nanopores with various pore diameter and pore depth. An alumina layer is formed along the pores which separate the pores from the aluminium bulk (Fig. 8.10). High aspect ratio and tunable pore dimensions make AAO a desirable material for fabrication of self-aliened materials and a commonly used...

Present RD Progress

Some vegetable oils such as SBO, linseed oil and rapeseed oil have a high degree of unsaturation, depending on the amount of linoleic and linolenic acid derivatives. As a result, the thermo-oxidative stability of these oils is poor and leads to polymerization, resulting in gummy and resinous products at elevated temperatures. Their use as lubricants without reduction of unsaturation can cause deposit formation, corrosive action, and damage with relatively short useful service life. One of the...

The Role of Boric Acid Additive Size on Green Lubricants Performance

Conservation Schematic Diagram

Based on the success of using micron-scale boric acid particles as an additive, efforts were made to determine the relative performance of sub-micron and nano scale boric acid particles in canola oil for metal forming applications. Despite several patents 66, 67 on the subject, there are no studies in the archival literature that quantitatively investigate the performance of boric acid particle additives in the colloidal size range. Recently, Lovell et al. 68 studied the tribological...

Results From Finite Difference Analysis

13.8.1.1 Nonlinear Transient Analysis The analysis gives the orbital trajectory within the clearance circle, which is not obtainable using a simplified theory linearised perturbation theory . The stability of the system was studied by simulating the journal centre trajectory and thereby estimating a stability parameter which is the function of speed. Figures i3.i8 and i3.i9 show the journal locus for constant load for different groove angles 36 and i2 . For constant load it is found that the...

Natural Vacuum Distillation

Natural Vacuum

The majority of currently used water desalination methods require a large amount of energy input in the form of heat or electricity. Use of renewable energy sources such as wind, solar, geothermal and biomasses will result in a cleaner environment and sustainable energy production. Different desalination methods can take advantage of a number of these renewable energy sources. Among these methods is a relatively new procedure which aims to mimic the natural hydrological cycle of water, known as...

Investigation of the Petal Effect

Hierarchical Structured Surface

Plant leaves and petals provide an example of surfaces with high CA and high and low CA hystereses. Bhushan and Her 4 studied two kinds of superhydrophobic rose petals 1 Rosa Hybrid Tea, cv. Bairage and 2 Rosa Hybrid Tea, 0 tilt angle 180 tilt angle Fig. 2.3 Optical micrographs of water droplets on Rosa, cv. Bairage at 0 and 180 tilt angles. Droplet is still suspended when the petal is turned upside down 4 0 tilt angle 180 tilt angle Fig. 2.3 Optical micrographs of water droplets on Rosa, cv....

Biodegradability and Eco Toxicity

ASTM D6081 127 method covers the procedures to be used in the preparation of lubricants or their components for toxicity testing in aquatic systems. This method discusses the techniques for the preparation of test materials for toxicity testing of poorly water soluble lubricants or their components under acute or chronic exposure conditions with fish, large invertebrates or algae. Other methods for aquatic toxicity are OECD fish embryo toxicity tests and OECD acute fish toxicity tests. In Fish...

Tribo Chemical Activation of Green Eco Cements

Melamine Formaldehyde Flowchart

Abstract Due to growing global demand for cement, the production of cement worldwide has significantly increased in the past 15 years, and this trend is the most significant factor affecting the technological and manufacturing advancements in the cement industry. While the increase in demand for cement reflects the growth of national economies, the production of cement clinker is ecologically harmful because it consumes considerable energy and natural resources, and it emits many pollutants...

Self Lubricating Behavior of Aluminum Graphite Composites

Aluminum alloys are promising materials in high technology automotive fields owing to their excellent specific mechanical and physical properties such as low density, good resistance to corrosion and low thermal expansion. However, their low resistance to wear under poor lubricating conditions and their severe seizure and galling under boundary lubrication conditions are the main concerns for their high performance tribological applications. With solid lubricant particle dispersion in the...