Presentasi Alumina Silicon Carbide Ekky

8/11/2019 Presentasi Alumina Silicon Carbide Ekky

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of Al2O3/SiC Composite

efractories

by Molten Aluminum andAluminum Alloy

Presented by ekky al ghazaly13707002


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Wettingcharacteristic

Effect ofmagnesium

Effect on Siand alloy in

refractory onthe wettingbehavior

disccussion

Experimental result

Wetting test

Experimental procedure

Aluminasiliconcarbide

conclusions


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Alumina-silica refractory brick is produced

from various combinations of alumina and

silica-containing materials.

The alumina-silicon carbide is manufactured by adding fine

aluminum powder to a body of silica-alumina type refractorycompound, mixing, molding and drying the resultant mixture to

obtain a green body and finally firing the green body in an

atmosphere containing predominantly a carbon oxide gas. [4]

www.google.com


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[2]

SiC has a modulus of elasticity of 410 GPa, with no

decrease in strength up to 1600C, and it does not melt at

normal

ressures but instead dissociates at 2600C. 3

Black Silicon Carbide (SiC) is an extremely

hard man made mineral that possesses high

thermal conductivity (100 W / m-K ) [3]

It also has high strength at elevated

temperatures (at 1000C, SiC is 7.5 times

stronger than Al2O3). [3]


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[5]


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Dissolution of Si ocurred in the molten

Al

Most of the past effort on

this topic was to improve the

wetting of SiC by aluminum

on modifying the aluminum

with surface active alloying

elements and/or the SiC by

surface coating.


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Tensile stress

wouldultimately

cause

cracking in

the

refaractory

Reducing the wettability

between the ceramic and liquid

metal


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[6]

Refractory plates (12 mm x 12 mm x 3 mm)

Aluminum pigs 99,99%

Aluminum alloy 5083

The sessile drop unit, schematic sketch


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sv = surface energy of the

solid sl = solid liquid interfacial

energy

lv = surface tension of liquidmetal

www.wikipedia.com


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The initial contact angle

between the TC substrate

and liquid Al was an obtuse

angle of 1250

The contact angle was found

to decrease gradually to a

value of 820during hold time

of 65 minutes.

Contact angle


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Drop height

Dropbase

diameter

Dropvolume

Contact angle


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The TC base material displayed the best wetting-resistance

performance among the three TCON substrateThe CA with pure aluminum are always higher than the

molten 5083 Al-Mg alloyMg addition in the

molten Al drop

interaction with the

metal / refractory

interface

Mg silicides or carbides


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BSE photomicrographs andmicroprobe mapping of the

cross section of the molten

aluminum 5083 alloy droplets

on (a) TQ, (b) TC,

and (c) MC substrates at 9001C

for 1 h.


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For all types showed a high concentration of silicon in

the Al drop, indicates the Si diffused from refractory

into the liquid Al drop during experiment .

Al was found to penetrate into the porosity of the the

refractory substrate.

6500

C

Chemical elements present

and distribution examined

by SEM / EPX and electron

microprobe


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Back scattering scanning electron photomicrograph of a section of the TC

substrate reacted with (a) a molten Al droplet, and (b) a molten Al 5083

alloy droplet, after 2 h at 900C.

Plenty of Si was found scattering in the Al drop, Si diffusion was driven

by the concentration gradient of Si in Al, resulting more precipitation at

the interface

This finding that interfacial regions are preferred position for the

element transferring across the interface and into the other phase


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Mg alloy

Larger drop base area

Lower drop height

Smaller contact angle

BSE photographs of the section of the aluminum 5083 alloy droplets on (a) TQ, (b)

TC, MC substrats at 900 C for 1h


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Wetting characteristic

Contact angle

can be

decreased

Increasing the surface energy of the solid

Decreasing the solid / liquid interfacial energy

Decreasing the surface tension of the liquid


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Effect of magnesium in the alloy on wetting behaviors

Add Mg to liquid drop accelerates the interaction with the substrate,beside that another investigation indicated that the one of the main

functions of Mg as a surfactant element is to reduce any aluminum

oxide that may be present in the interface

Those reactions could occurs under the experimental condition (900oc)

Mg is also capable of forming magnesium aluminum spinel

The microchemistry of these product in the interface is important from point of

view of wettability


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Lowest % of Al203 Higher wetting resistance (TC)

The grain size

Distribution

Morphology of Al2O3 particles

TCON substrate

Wettability

Particles

Round-shaped Al2O3 < angular-shaped Al2O3 ( surface area )

Check it

Angularity particles can act as point of stress concentration where mayinitiate as mechanical deformation proceeds


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Effect on Si and Al in the refractories on the wetting behaviour

Fee Si around Sic particles improve the spreading of molten

aluminum on the SiC substrate

Aluminum alloy better wet siliconized Sic substrate than not

Al adition to TCON substrate had a positive effect ini increasing

the contact angle by reducing the compotitional gradientof Al

diffusion from molten drop to TCON base, slowing down the

diffusion rate and thus resulting in better wetting resistance of thebase materials

Si

Al

To rank the wetting performance, the TCON material should

be made of Al, Si and Al2O3 conctents in TCON


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Among the three refractory substrates tested,

namely

TC, TQ, andMC, it was found that TC showed a

higher

contact angle values than TQ and MC, which

indicated

that TC shows better nonwetting performance in a

molten Al/Al alloy.

The difference in the wetting properties

among three types of refractories is

attributed to their microstructural and

compositional variations.A strong diffusion of silicon from the

substrate into the liquid metal drop was

observed

Al was found to move into the refractory.


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1. http://www.hxabrasives.com/rSiC.htm

2. http://www.cumi-murugappa.com/emd/datasheet/sic_monolithics.pdf

3. http://www.patentstorm.us/patents/4069060/fulltext.html4. http://www.sentrotech.com/silicon-carbide-products

5. Pramod Koshy, et al. Effect of Silica on High-Temperature Interfacial

Phenomena of Monolithic Refractories withAl Alloy. The Minerals, Metals &

Materials Society and ASM International.2008
http://hxrefractory.en.made-in-china.com/product/gbWEUXcVCKhu/China-Hothttp://www.hxabrasives.com/rSiC.htmhttp://www.cumi-murugappa.com/emd/datasheet/sic_monolithics.pdfhttp://www.patentstorm.us/patents/4069060/fulltext.htmlhttp://www.sentrotech.com/silicon-carbide-productshttp://www.sentrotech.com/silicon-carbide-productshttp://www.sentrotech.com/silicon-carbide-productshttp://www.sentrotech.com/silicon-carbide-productshttp://www.sentrotech.com/silicon-carbide-productshttp://www.sentrotech.com/silicon-carbide-productshttp://www.patentstorm.us/patents/4069060/fulltext.htmlhttp://www.cumi-murugappa.com/emd/datasheet/sic_monolithics.pdfhttp://www.cumi-murugappa.com/emd/datasheet/sic_monolithics.pdfhttp://www.cumi-murugappa.com/emd/datasheet/sic_monolithics.pdfhttp://www.hxabrasives.com/rSiC.htmhttp://hxrefractory.en.made-in-china.com/product/gbWEUXcVCKhu/China-Hot

Presentasi Alumina Silicon Carbide Ekky

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