Presentation KERAMIK 1

8/11/2019 Presentation KERAMIK 1

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1. Inggit Dwi Wismoyowati (521341202. Fitiyatun Nur Jannah (5213412006)

3. Nur Rofiah (521341204. Siti Nur Afifah (52134120


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The important characteristics of a powder canbe categorized into four groups:

1. physical characteristics,2.

chemical composition,3. phase composition, and4. surface characteristics


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Types of articles1. Primary Particles

A primary particle is a discrete, low-porosity

unit that can be either a single crystal, apolycrystalline particle, or a glass. If anypores are present, they are isolated from eachother.


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2. AgglomeratesAn agglomerate is a cluster of primaryparticles held together by surface forces, byliquid, or by a solid bridge. Agglomerates areporous, with the pores being generallyinterconnected.


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Agglomerates classified into two types:soft agglomerates .

Soft agglomerates are held together by fairlyweak surface forces and can be broken down intoprimary particles by ultrasonic agitation in aliquid.

hard agglomeratesHard agglomerates consist of primary particlesthat are chemically bonded by solid bridges; theytherefore cannot be broken down into primaryparticles by ultrasonic agitation in a liquid


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3. ParticlesParticles can be viewed as small units that moveas separate entities when the powder isdispersed by agitation and can consist of primary

particles, agglomerates, or some combination ofthe two.4. Granules

The term granules refers to large agglomerates(100 1000 m in size) that are deliberately formedby the addition of a granulating agent (e.g., apolymer-based binder) to the powder, followedby tumbling or spray drying.


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5. FlocsFlocs are clusters of particles in a liquidsuspension. The formation of flocs is undesirablebecause it decreases the packing homogeneity of

the consolidated body.6. ColloidsA colloid is any system consisting of a finelydivided phase in a fluid. A colloidal suspension(or sol) consists of fine particles dispersed in aliquid. The particles, referred to as colloidalparticles. The size range for colloidal particles isapproximately 1 nm to 1 m.


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7. AggregatesAn aggregate is a coarse constituent in amixture, which usually also contains a fineconstituent called the bond. Pebbles inconcrete are an example, with the finecement particles forming the bond.


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Definition of Particle SizeFor a spherical particle, the diameter is taken asthe size. However, the size of an irregularlyshaped particle is a rather uncertain quantity.One simple definition of the size of an irregularlyshaped particle is the diameter of the spherehaving the same volume as the particle. If anirregularly shaped particle is allowed to settle in

a liquid, its terminal velocity may be comparedwith that for a sphere of the same densitysettling under similar conditions.


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Rata- rata ukuran partikel

Dimana : Xi= ukuran partikel (diameter partikel),ni =nomor ukuran partikel


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article ShapeParticle shape influences the flow properties andpacking of powders as well as their interactionwith fluids (e.g., viscosity of a suspension)for the fairly simple geometries the quantitativecharacterization of particle shape can be fairlycomplexFor elongated particles, the most common way ofrepresenting the shape is in terms of the aspectratio, defined as the ratio of the longestdimension to the shortest dimension.


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Measurement of

Particle Size andSizeDistribution

Microscopy Sieving

Sedimentation

ElectricalSensing ZoneTechniques(the CoulterCounter)

Light Scattering

X-ray LineBroadening


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The use of sieves for separating particles intofractions with various size ranges.The particles are classified in terms of theirability or inability to pass through an aperture

with a controlled size. Sieves with openingsbetween approximately 20 m and 10 mmare constructed with wire mesh and areidentified in terms of a mesh size and a

corresponding aperture size.Sieving may be carried out in the dry or wetstate by hand or by a machine.


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In the sedimentation method, the powdermay be introduced as a thin layer on top of acolumn of clear liquid (sometimes referred toa two-layer or linestart technique), or it maybe uniformly dispersed in the liquid (thehomogeneous suspension technique). Theparticle size distribution is determined bymeasuring the change in concentration (ordensity) of the suspension as a function oftime, height along the suspension, or both.


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In the Coulter counter, the number and sizeof particles suspended in an electrolyte aremeasured by causing them to flow through anarrow orifice on either side of which anelectrode is immersedAs a particle passes through the orifice, itdisplaces an equivalent volume of theelectrolyte and causes a change in theelectrical resistance, the magnitude of whichis proportional to the volume of the particle.


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For a system of fine particles dispersed in aliquid or gas, measurement of Is provides aversatile and powerful technique for determiningparticle size data.

Large particles tend to reflect light back towardthe source in much the same way as this pagebackscatters light towards the readers eyes. The particle size is decreased towards thewavelength of the light, there is a greatertendency for the light to be scattered in theforward direction, i.e., at small angles to thedirection of the incident beam


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Because of the complexity of the generaltheory, three limiting cases, stated in termsof the ratio of the particle size x to thewavelength of the incident light, arecommonly considered:1. x >

, Fraunhofer diffraction theory


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Computerized software available with mostmodern diffractometers allow for fairly rapid andaccurate determination of the crystal size by theline broadening technique.the primary particles consist of single crystals,then the crystal size determined by x-ray linebroadening will be comparable to the particlesize determined by other methods such aselectron microscopy.For polycrystalline primary particles or

agglomerates, it willbe much smaller than the size determined byother methods.


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Techniques for measuring the surface area arebased on the phenomenon of gas adsorptionAdsorption is commonly divided into twocategories: 1. Physical adsorption in which the adsorption is brought

about by physical forces between the solid and the gasmolecules (similar in nature to the weak van der Waalsforces that bring about condensation of a vapor to aliquid)

2. Chemical adsorption or chemisorption where theadsorbed gases will have developed strong chemicalbonds with the surface


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The validity of the BET equation is commonlystated to extend over the range of relativepressures ( p/po values) of 0.05 and 0.3, butthere are numerous examples where the BETplot departs from linearity at relativepressures below 0.2.

Presentation KERAMIK 1

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