Seeking Low Ice Adhesion PDF Download
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Author: John M. Sayward
Publisher:
ISBN:
Category : Adhesion
Languages : en
Pages : 92
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Book Description
Icing impairs operation of helicopters and other aircraft, antennae, power and communication lines, shipping and superstructures, canal locks, etc. Prevention or easier removal of icing requires reduction of its adhesion strength. Literature study shows that adhesion results from secondary (van der Waals) forces yet exceeds normal cohesive strengths. It depends on free surface energy, low contact angle, good contact and wetting, cleanliness, and texture. Modes of adhesion testing are briefly discussed. Poor adhesion occurs with low energy surfaces or contaminants, e.g. hydrocarbons, fluorocarbons, waxes, oils, etc., particularly when textured or porous. The resulting low contact angle, poor wetting and occlusion of air at the interface weaken the bond or provide stress loci which can initiate cracks and failure. Coefficient of expansion differences may help in release of ice. Further ideas appear among the 100 abstracts presented. A survey of over 300 manufacturers produced over 100 replies. Half of them offered some 100 products deemed worth testing. These are listed with addresses and contacts.
Author: John M. Sayward
Publisher:
ISBN:
Category : Adhesion
Languages : en
Pages : 92
Get Book Here
Book Description
Icing impairs operation of helicopters and other aircraft, antennae, power and communication lines, shipping and superstructures, canal locks, etc. Prevention or easier removal of icing requires reduction of its adhesion strength. Literature study shows that adhesion results from secondary (van der Waals) forces yet exceeds normal cohesive strengths. It depends on free surface energy, low contact angle, good contact and wetting, cleanliness, and texture. Modes of adhesion testing are briefly discussed. Poor adhesion occurs with low energy surfaces or contaminants, e.g. hydrocarbons, fluorocarbons, waxes, oils, etc., particularly when textured or porous. The resulting low contact angle, poor wetting and occlusion of air at the interface weaken the bond or provide stress loci which can initiate cracks and failure. Coefficient of expansion differences may help in release of ice. Further ideas appear among the 100 abstracts presented. A survey of over 300 manufacturers produced over 100 replies. Half of them offered some 100 products deemed worth testing. These are listed with addresses and contacts.
Author: John M. Sayward
Publisher:
ISBN:
Category : Adhesion
Languages : en
Pages : 83
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Book Description
Author: K. L. Mittal
Publisher: John Wiley & Sons
ISBN: 1119640539
Category : Technology & Engineering
Languages : en
Pages : 704
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Book Description
The book containing 18 chapters is divided into three parts: Part 1: Fundamentals of Ice Formation and Ice Characteristics; Part 2: Ice Adhesion and Its Measurement; and Part 3: Methods to Mitigate Ice Adhesion. The topics covered Include: Factors influencing the formation, adhesion and friction of ice; ice nucleation on solid surfaces; physics of ice nucleation and growth on a surface; condensation frosting; defrosting properties of structured surfaces; relationship between surface free energy and ice adhesion to surfaces; metrology of ice adhesion; test methods for quantifying ice adhesion strength to surfaces; interlaboratory studies of ice adhesion strength; mechanisms of surface icing and deicing technologies; anti-icing using microstructured surfaces; durability assessment of icephobic coatings; bio-inspired icephobic coatings; challenges in rational fabrication of icephobic surfaces; protection from ice accretion on aircraft; and numerical modeling and its application to inflight icing.
Author: David N. Anderson
Publisher:
ISBN:
Category :
Languages : en
Pages : 18
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Book Description
Author: K. L. Mittal
Publisher: John Wiley & Sons
ISBN: 1119640377
Category : Technology & Engineering
Languages : en
Pages : 704
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Book Description
This unique book presents ways to mitigate the disastrous effects of snow/ice accumulation and discusses the mechanisms of new coatings deicing technologies. The strategies currently used to combat ice accumulation problems involve chemical, mechanical or electrical approaches. These are expensive and labor intensive, and the use of chemicals raises serious environmental concerns. The availability of truly icephobic surfaces or coatings will be a big boon in preventing the devastating effects of ice accumulation. Currently, there is tremendous interest in harnessing nanotechnology in rendering surfaces icephobic or in devising icephobic surface materials and coatings, and all signals indicate that such interest will continue unabated in the future. As the key issue regarding icephobic materials or coatings is their durability, much effort is being spent in developing surface materials or coatings which can be effective over a long period. With the tremendous activity in this arena, there is strong hope that in the not too distant future, durable surface materials or coatings will come to fruition. This book contains 20 chapters by subject matter experts and is divided into three parts— Part 1: Fundamentals of Ice Formation and Characterization; Part 2: Ice Adhesion and Its Measurement; and Part 3: Methods to Mitigate Ice Adhesion. The topics covered include: factors influencing the formation, adhesion and friction of ice; ice nucleation on solid surfaces; physics of ice nucleation and growth on a surface; condensation frosting; defrosting properties of structured surfaces; relationship between surface free energy and ice adhesion to surfaces; metrology of ice adhesion; test methods for quantifying ice adhesion strength to surfaces; interlaboratory studies of ice adhesion strength; mechanisms of surface icing and deicing technologies; icephobicities of superhydrophobic surfaces; anti-icing using microstructured surfaces; icephobic surfaces: features and challenges; bio-inspired anti-icing surface materials; durability of anti-icing coatings; durability of icephobic coatings; bio-inspired icephobic coatings; protection from ice accretion on aircraft; and numerical modeling and its application to inflight icing.
Author: Grant M. Schneeberger
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Author:
Publisher:
ISBN:
Category : Frozen ground
Languages : en
Pages : 62
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Book Description
Author: Raj K. Arya
Publisher: John Wiley & Sons
ISBN: 1394207298
Category : Technology & Engineering
Languages : en
Pages : 628
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Book Description
FUNCTIONAL COATINGS A must-own resource for understanding functional coatings and their revolutionary potential Functional coatings are those which provide not only the protection and performance enhancement of a conventional coating, but also offer additional properties tailored to meet the specific requirements of a given industry or application. They have applications in a huge range of sectors, including automotive, aerospace, healthcare, energy, and more. Coatings with properties like fire retardancy, antimicrobial properties, or controlled drug release have the potential to revolutionize entire industries. Functional Coatings offers a comprehensive resource for engineers and researchers looking to understand these coatings and the opportunities they provide. Beginning with an overview of the subject’s foundations and industrial significance, the book analyzes numerous coating methods and their properties, with a particular focus on anticorrosion coatings. The result is an indispensable resource for professionals in virtually any technological industry looking to understand the benefits of a cutting-edge toolkit. Functional Coatings readers will also find: Coverage of synthesis, durability, reproducibility, cost-effectiveness, specialized surface morphology, and environmental friendliness of each coating Detailed discussion of antimicrobial coatings, fire-retardant coatings, self-healing coatings, nanopowder coatings, coatings for marine applications, and many more Applications of additives, machine learning, and sophisticated characterizations, etc. as per industry requirements Functional Coatings is ideal for researchers, engineers, and industry professionals working with any area of technology where coatings have purchase.
Author: Cold Regions Research and Engineering Laboratory (U.S.)
Publisher:
ISBN:
Category : Engineering
Languages : en
Pages : 178
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Book Description
Author: Rebekah Douglass
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
In-flight ice accretion on fixed-wing aircraft and rotorcraft can be catastrophic if not mitigated. Most modern ice protection systems are active systems, which require electrical or mechanical power to remove accreted ice. Despite their proven capability to protect aircraft from ice accretion, these methods can reduce the aerodynamic efficiency of the vehicle and increase its weight, cost, and complexity. Scientists and engineers now seek passive, erosion-resistant materials and coatings with low ice adhesion strength. Ideally, such materials, when applied to vulnerable components of an aircraft, would cause any ice to shed off the surface under normal aerodynamic loading. To aid in the development of low-ice-adhesion-strength materials, the growth and structural behavior of impact ice in a wide range of atmospheric conditions must be characterized. Facilities such as the NASA Icing Research Tunnel (IRT), the Anti-Icing Materials International Laboratory (AMIL), and the Penn State Adverse Environment Research Testing Systems (AERTS) laboratory, to name a few, have spent decades investigating the relationship between ice adhesion strength, temperature, surface roughness, airspeed, and other parameters. The structural behavior of ice has been examined under pure shear, tension, and compression, and mixed-mode loading. However, one important loading consideration that has not been widely investigated on atmospheric ice is strain rate. Very few published ice adhesion studies report the strain rate applied to the ice samples. Several previous studies of laboratory-prepared ice in compression revealed that ice undergoes a ductile-to-brittle transition under high strain rate conditions, and that the adhesion strength is a power function of the strain rate. Other studies, in which lab-prepared ice was loaded in pure shear, reported similar trends. It is unclear whether the same behavior can be expected of dynamically-accreted atmospheric impact ice. Knowledge of the relationship between impact ice adhesion strength and strain rate is important because it can be used to design future ice protection systems, and it may dictate the appropriate course of action for a pilot flying through icing conditionsfor instance, whether a helicopter pilot should increase the rotor speed rapidly or slowly to induce shedding of the ice. NASA Glenn Research Center funded the design and construction of a new centrifuge-style ice adhesion test rig (AJ2) by the Penn State AERTS lab. The ice is accreted dynamically by spinning flat metal test coupons at high speed inside a simulated icing cloud environment, so the water droplet sizes and impact speed are representative of in-flight icing, without the need for a wind tunnel. The rig motor allows for user-defined acceleration rates, so the strain rate on the ice can be controlled. The adhesion strength of the ice is calculated from the voltage output of strain gauges mounted on the cantilever beams holding the test coupons. Unlike other small-scale adhesion test methods, AJ2 allows researchers to collect real-time adhesion data and control the testing environment without any direct interaction with the ice, thus preserving the fidelity of the data. As per NASA requirements, ballistic and structural analysis was performed on the rig to verify its safety. The design and analysis of the AJ2 rig is described in detail in this paper. Many experiments were performed at Penn State to investigate how the adhesion strength of impact ice related to the strain rate applied to it. Stainless steel test coupons of known surface roughness were tested in a range of environmental temperatures. The strain rates applied to the ice ranged between 5x10-7 and 5x10-5 s-1. It was discovered that a similar power function exists between strain rate and adhesion strength as found in the freezer-ice studies described in the literature. Despite scatter in the data, regression analysis determined the trends to be statistically significant. The data suggests that strain rate has a stronger effect on adhesion strength for smoother surfaces as opposed to rougher surfaces. The power 1/n for a coupon roughness of 64 nm (Sa) was double that of the 80-nm coupon; this was the case for both tested temperatures. Similarly, lower temperatures caused a higher power 1/n and coefficient c in the power function. The variation of the coefficient with temperature is consistent with Glens power law for the creep of glacier ice in compression. However, Glen did not observe a variation of the power with temperature. The value of n in the current study ranged from 2.5 for the smoothest sample at the coldest temperature, to 9.7 for the roughest sample at the warmest temperature. In most cases, n was within the range of previously-reported values in literature (1.5 to 6). These findings suggest that the creep behavior of atmospheric impact ice in shear is similarbut not identicalto freezer ice in compression. The proven strain rate testing capabilities of the AJ2 rig will aid icing research efforts by yielding baseline prediction data for future design of ice-resistant materials.
