Shock-induced reactions in ball-milled Ti-Si powder mixtures

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XI EPNM
Shock-induced reactions in ball-milled Ti-Si
powder mixtures
J. J. Liu1, N. F. Cui2, P. W. Chen2
1Faculty of Science, Beijing University of
Chemical Technology, Beijing 100029, China 2State
Key Laboratory of Explosion Science and
Technology, Beijing Institute of Technology,
Beijing, 100081, China
2012.5.4 Strausbourg France
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Outline
Introduction
Experimental
Results and discussion
Conclusions
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Introduction
Composition TiSi, TiSi2, Ti5Si3, Ti5Si4
Combustion synthesis Self-propagating
reaction Mechanical alloying Shock induced
reaction
Ti-Si system
Synthesis
Heat resistant material High hardness Microelectro
nics Photocatalyst
Application
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Ti-Si photocatalyst
Ritterskamp P., et al, Angew.Chem. Int. Ed,
467770, 2007

• As new functional materials, the light-absorption
  characteristics in UV-visible region
  (ca.360?800nm) of TiSi2 are ideal for solar
  applications and have a good photocatalytic
  activity of splitting water into hydrogen.

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Ti-Si photocatalyst
Liu J J., et al, AIP Conf.Proc., 1426 1403, 2012
The coupled photocatalyst of Ti5Si3 and Ti8O15
were shock-sythesized by adding oxidant and
exhibits superior photocatalytic activity.
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Experimental

• A planetary ball mill (Fritsch, P-7) was used for
  grinding the Ti-Si samples.

300 steel balls of 3mm diameter (?32g)and 8g of
mixed powder in 80 ml bowl At 300?900rpm for 3h
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Experimental

• .
• detonator
• (2) upper cover
• (3) booster charge
• (4) nitromethane
• (5) bottom cover
• (6) flyer
• (7) steel protection tube
• (8) copper sample container
• (9) sample
• (10) copper screw lid
• (11) PVC plastic tube
• (12) steel momentum block

Scheme of shock-loading apparatus
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Experimental conditions
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Photocatalytic test
Set-up scheme of photocatalytic evaluation 1. Hg
lamp, 2.rubber plug, 3. quartz reactor, 4.water
and photocatalyst, 5.magnetic stirrer, 6.dark
box.
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Results and discussion
Q7 The milled Ti-Si2 reacted to form little
Ti5Si3 at 900rpm. 414The next shock does not
initiate further reaction.
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Results and discussion
Q8 The milled Ti5-Si3 has not any reaction at
900rpm. 415The next shock initiated reaction to
form little Ti5Si3 .
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Results and discussion
Why?
Figure 5. XRD patterns of samples derived from
Ti-Si2 at different conditions a ? direct shock
loading at 3.37km/s without ball-mlling b ?
ball-milling after 3h at 900rpm and c ? shock
loading of sample b at 2.25km/s.
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Results and discussion
Figure 6 XRD patterns of samples derived from
Ti5-Si3 at different conditions a ? direct shock
loading at 2.25km/s without ball-mlling b ?
ball-milling after 3h at 900rpm and c ? shock
loading of sample b at 2.25km/s
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Results and discussion
Partly react
no reaction
Partly react
Obviously react
Figure.7 SEM images of samples. (a) Q7,
(b)Q8,(c)414, (d)415.
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Results and discussion
Mill-activated(agtb)
(MillShock)-activated(bgta)
Figure.8 DSC analysis of Ti-Si samples
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Photocatalytic test for producing hydrogen
Figure.9 Curves of photocatalytic activity for
Ti-Si samples
Same activity sequence shockedmilled(a)gt
shocked(c) gtmilled (b)
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Conclusions

• Milling treatment to some extent could decrease
  the threshold of shock reaction of Ti-Si and the
  reaction product is different from the designed
  one.
• The direct shock synthesis may give a designed
  Ti-Si product under heavier loading conditions.
• Both of milling and shock loading can activate
  and initiate reaction of the Ti-Si samples which
  exhibit better photocatalytic activity than that
  of only milling or shock loading.

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Thanks for your attention !