microsoft powerpoint - glass fibers and their applications_2 [compatibility mode].pdf

8/10/2019 microsoft powerpoint - glass fibers and their applications_2 [compatibility mode].pdf

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Glass fibres and theirGlass fibres and theirGlass fibres and theirGlass fibres and their applications(2)applications(2)applications(2)applications(2)

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Glass optical fiber


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Glass Fibre Bragg grating


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Supercontinuum generation due to nonlinear effects

Applications of supercontinuum generation:

- Photonic device testing

- Optical coherence tomography

Supercontinuum generation in taperedbismuth-silicate fibres

Study of ORC, Univ. Southampton, UK

-

- Low-coherence white light interferometry

- Time and Frequency Standards

* Produce clocks equal or more

accurate than best atomic clock

* GPS, secure transmission, military, etc.

Cooperation with ORC University ofSouthampton, UK


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Structure of an optical fibre

An optical fibre is thin cylindrical glass fibre that acts as a

dielectric waveguide by guiding light (electromagnetic waves)

from one end to the other

125 m

250 m8 m

Dimensions are for a typical telecom fibre (silica-based)

ncore > n claddingS.O.Kasap, Illusrated dictionary of Optoelectronics and Photonics, 1999


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Total internal reflection in an optical fibre


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Step index fibre

A step-index optical fibre has a core with constant

refractive index and a cladding with a lowerrefractive index

6.7

Saleh, Teich Fundamentals of Photonics 1991 Ed. Wiley


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Compatibility requirements for core andcladding glasses of a fiber preform:

Transition tem erature T matchin

Refractive index (n) matching

n1> n2; NA = sin () = (n12 n22)1/ 2n0

n1

2n

Core

Cladding

Cladding

T = (Tg)clad - (Tg)core< 30

Thermal expansion coefficient () matching

< 2.0

10

-6

[

-1

]


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NA of a fibre

The NA defines the light-gathering ability of a fibre

n0

n2

n1

Large acceptance angle of light: higher light-gathering ability

Fine confinement of light within the core: low bend loss

Smaller mode area and high light intensity: non linearityenhancement

Advantages ofHigh NA:

High nonlinear effect can be obtained from high NA fibre


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Low

NA

High

The NA defines the light-gathering ability of a fiber

High NA fiber

Large acceptance angle of light: higher light-gathering

abilityFine confinement the light within the core: low bend loss

Smaller mode area and high light intensity: non linearityenhancement

Advantages:


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High NA fiber

NAME COUNTRY NA MATERIAL Date

Toray JAPAN 0.63 POF before2004

Blaze Photonics UK 0.8 PCF 2006

Companies producing high NA fibres and their techniques

Sys.Concent CANADA 0.4 PCS 2004

Ceram Optec US 0.3-0.53 Silica/silica2006

Fibrehome CHINA 0.3 Silica/silica before2004

Polito ITALY 0.9 Tellurite glass 2007


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Glass fabrication

Batching powdersSample processing:

cuting and polishing

Glass annealing

Melting in Pt crucibleStirring homogeneity

Casting on a brassmould preheated

Mixing powders


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Glass fabrication

Thermal characterization and compatibility of core and cladding

DSC of TZN and TZKGeSi glass DMA of TZN and TZKGeSi glass


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FTIR characterization


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Vickers hardness measurement


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Fibre drawing


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Fibre drawing

Nitrogen gasflux

Temperatureof the furnace

Feeding speedof the Preform

Rotating speedof the drum

Moving speed

of the translator


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Fibre drawing

Drawing temperature

( furnace)()

Feeding speed

Parameters

o pre orm mm m n

Flux of nitrogen

gas(top)(cm-3/min)

Flux of nitrogen gas

(bottom)(cm-3/min))

Rotating speed

of drum(r/min)


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Fibre drawing

D2V = d2v


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Glass optical fibres for transmission


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Glass fiber for Lasers

Surgery

CD/DVD players

Engraving

Cutting/welding

Speed checkMilitary


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New Trend for optical fiber in textile


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e-health wearable systems


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Glass optical fiber applications in textile :safety

O h


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Smart/interactive textiles (SIT) are materialsand structures that sense and react toenvironmental conditions or stimuli, such as

those from mechanical, thermal, chemical,electrical, magnetic or other sources.

Others ....

SIT are no longer a science-fictionfantasy. For example, there are in themarket self-cleaning carpets, memory-shaped and environment-responsivetextiles, and anti-insomniac micro-fibers.

M i


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Processing

Trigger orStimuli

Sensing

CONTRO

The sensors provide anerve system to detectsignals

The processor analyzesand evaluates the si nals

Meccanism

ActuationResponseor Action

LING

The actuators act upon thedetected and evaluatedsignal either directly orfrom a central control unit


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For sensors - actuators:

optical fibre

photo-sensitive materials conductive polymers

thermal sensitive materials

shape memory materials intelligent coating materials

micro- and nano-materials


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Depending on the manufacturing process, textileglass fibers are subdivided into(1) glass filaments and

(2) glass staple fibers, which are defined asfollows in ISO 6355:

1. A glass filament is a textile glass fiber ofracticall unlimited len th of a iven diameter

Textile glass fibers

drawn from molten glass.2. A glass staple fiber is a textile fiber of limitedlength (spun fiber) and of a given diameter.


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The largest market (by mass) of glass fibers isin thermal insulation (wool glass).The energy required to produce thermal

insulation products from fibreglasscomparesvery favorably with the energy which can besaved in heating/cooling applications over aew years.

This makes fibreglasswool one of the mostenergy-efficient commodity product on themarket today.

This is especially important where (USA i.e.)40% of the total energy usage is in residentialand commercial buildings.


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The second largest market (by mass) for fibreglassis incomposite materials.Of all glass filamentsca. 90% are used to reinforce a matrix.

Matrices can be plastics (both thermosetting andthermoplastic), bitumen, rubber, cement, gypsum, or othermaterials.The tensile strength and elastic modulus fibre glassreinforcement are much higher than those of the matrix

polymer.When the composite do not have to sustain a big stress,the glass fibers can simply act as filler reducing the overallcost of the composite. To achieve this, the fibers are coatedwithin milliseconds of exiting the spinneret with a mixtureor emulsion of organic molecules called the sizing. Thesizing system effectively acts as an adhesive which bondthe polymer to individual glass filaments.


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On a weight basis, more than 99% glass fibersin use today are spun from silicate (containing

at least 50% SiO2 on a molar basis) glassfibers.Other glasses are chalcogenideand 100%s ca g asses, w c are ma n y use oroptical fibers. For optical communication,extremely high purity silica with preciselycontrolled concentrations of doping ions to

adjust the refractive index are utilized.


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Textile glass fibers can also be categorized bythe type of products and the diameter of thefilaments:

Textile products, such as textile glass yarnsand plied yarns with filament diameters of 513 mm. Textile products are mostly woven and

and other applications.Reinforcement products such as mats,rovings, chopped strands, and milled fiberswith filament diameters of 924 mm. Thoseproducts are used as reinforcement inplastics, cement, and other materials.


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Chemical composition of textile glass fibers


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The mechanical properties of E glass fibers are by farinferior to those of carbon fibers. In the last decade, newglass fibers have been developed to offer performances

comparable to those of carbon fibers with competitiveprice. Those special glasses are used in niche markets andfor special applications.High strength glasses typically have higher amount of

High strength glasses (R and S)

. -

Alumina-Silica glass has a tensile strength 50% higherthan that of standard E-glasses.These glasses have higher melting temperature than theconventional E-glasses. They are melt in special smallamount and very high temperature melters. As a results,

they are expensive and used only in specialty applicationswhere very high thermal durability and strength retentionare required (e.g. in containers under high internalpressure).


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The density of 2.6 g/cm3, which ishigh compared to plastics, is notsufficient for large-surface, light-weight parts (airplane construction).For such arts, fibers of lower

Properties of glass fibres

density and higher modulus ofelasticity (aramidand carbon fibers)have been developed.


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Good resistance to weathering and heat,

nonflammability, good dielectric properties,low thermal expansion, and, depending onthe type of textile glass, good resistance tocorros on, are a ona c arac er s cs o

textile glass fibers.


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The amount of glass fibers produced has

increased during the last decades. In 2011about 4 106t of textile glass fibers wereconsumed b the market worldwide.

Glass fibers are strongly used in thosesectors where lightness must be combinedwith strength and a competitive price. Glassfibers are by far the most widely used

reinforcement for plastics.


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The leadership of the market of textileglass fibers is hold by Owens Corning

OCV Reinforcements.The market has been dominated in thelast century by North America and

.

However, in the last decade a big part ofthe production has moved to emergingcountries. In 2007, three of the mostimportant producers of textile glassfibers were located in Asia, owningalmost 30% of the market share.


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The success of textile glass fibers (principally

E glass) can be explained by considering theenergy intensity of their manufacture, which isrelatively low (1332 MJ/kg) compared, forexamp e, o a o car on ers

MJ/kg).Roving constitutes about 80% of the textileglass fibers global production with an annual

growth of 7%. The remaining 20% of theproduction is represented by glass fiber yarnswith a growth of 4% (2008).


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Production of glass fibers

The manufacture of textile glass fibers needsmany steps. The most important steps arereported in the Figure.

Production of of textile glass fibers


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M l i


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There are two commercial processes for themanufacture of glass filaments: the marblemelting process and the direct melt process.In the older indirect marble melting process,the production of glass and the glassspinning process are separate. The glass is

Melting process

n a y pro uce n e orm o g ass

marbles (1520 mm diameter), which arethen re-melted in a second phase in theglass forming process (two-stage process).This process is still in use today for making

fine filament yarns.


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Fiber drawing


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The fiber-forming process involvesattenuating glass filaments continuouslyfrom a platinum (Pt)rhodium (Rh) bushingby applying a mechanical drawing force atoff-take speeds of up to 80 m/s.Typical alloys used in glass-fiber

Fiber drawing

manu ac ure are a oys. a num s

used because of its extraordinary resistanceto oxidation at high temperatures and tocorrosion in contact with the melted glass;rhodium improves the thermal stability of the

platinum.


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The rhodium additions increase the hardness andstiffness of the alloy, which significantly enhancesthe lifetime of the bushing. An additional benefit isthe increased contact angle with the molten E-glass.Bushings may have 400, 800, 1200, 1600, or more

o es o . mm ame er. s ng e amen s

drawn from each hole. The filaments are collectedinto a bundle (strand) and wound as a spun cake ordirectly processed into rovings, continuous strandmats, or chopped strands.


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Formation of the filaments involves twobasic processes:

1. Efflux of molten glass from the bushingtips under the condition that


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The term towis used to define the smallestunitary element of the strand and represents

the number of filaments drawn from a singlebushing, which was commonly equal to 200.The number of fibresin a strand is made upfrom multiples of the bushing number.A rovingis commonly produced by assemblingmultiples of 200 filaments into the required sizeof roving as a separate operation.

However, with the development 24000 nozzlebushings, direct rovingscan be formed into afinal package immediately.


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Coupling agents (e.g., silanes) are used to improve theadhesion between glass fibers and specific polymers by

modifying the fiber surface.Film formers improve the wettability, the filamentsstrength, the textile processabilityand the cohesion of

Lubricants are necessary to reduce the coefficient offriction consenting to make further processing of theyarn possible. Due to the high coefficient of friction,textile glass strands without size cannot be processedfurther since they cannot be pulled off the cakes.

Post-Processing


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After the winding process, the strands arepost-processed in order to obtain differentproducts like roving assembling, twisting,strand chopping, and air-jet texturizing.

ost ocess g

Product designation


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Glass filament and glass staple yarns have astandard form of designation.Example EC934 Z28 where

g

CD11200 Z140 where


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Staple fiber can be principally obtained by

milled glass fibers or by chopped strands.Milled textile glass fibers with fiber lengthsof 0.2 mm are suitable as reinforcement ofthermoplastics.

The chopped strands have morehomogeneous length distribution. Typicalproducts are made of chopped strands with

lengths of 3, 4.5, 6, or 12 mm and are used inthe production of molding compounds andas reinforcement of thermoplastics.


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microsoft powerpoint - glass fibers and their applications_2 [compatibility mode].pdf