Title: Mixture of fuels approach for the synthesis of novel oxide powders: Utility of combustion synthesize
1Mixture of fuels approach for the synthesis of
novel oxide powders Utility of combustion
synthesized nanosize powders in the development
of corrosion and wear resistant Ni-composite
coatings
S.T. ArunaSurface Engineering DivisionNational
Aerospace LaboratoriesBangalore 560 017
2Dedicated to Prof. K.C. Patil
3- Out line of the talk
- Mixture of fuels
- CeO2-Al2O3 CeAlO3
- Plasma Sprayable powders
- SOFC application
- TBC application
- Application of combustion synthesized powders
- Metal Matrix composites
- Corrosion Wear resistant coatings
- Conclusions
4Mixture of fuels approach
Brown fumes
5ZTA-urea
ZTA-ureaglycineAA
ZrO2 8 nm Al2O3 9 nm
ZrO2 34 nm Al2O3 40 nm
S.A. 2.6 m2/g
S.A. 7.7 m2/g
6Unique features of mixture of fuels approach
- No. of moles of gases will be same
- Smaller particle size, higher surface area
- Lower sintering temperature
- Lower agglomeration
7Solution combustion synthesis of CeO2-Al2O3
(CeAl46) nano-composites by mixture-of-fuels
approach
Urea fuel
Flame temp. 1100 ?C
10.91?m
Mater. Res. Bull. (2008), doi10.1016/j.materresbu
ll.2008.09.034
828 nm
9Mixture of Glycine Urea
Flame temp. 900 ?C
8 ?m
75 CeAlO3
105-25 nm
Urea
UreaGlycine
(5.82 g/cm3 )
(3.53 g/cm3)
11Mixture of fuels approach for the preparation of
CeAlO3 by solution combustion process
- CeAlO3
- Oxide with lower oxidation state and an important
catalyst - Synthesized at 1350-1500?C in a reducing
atmosphere using H3BO3 flux - Heating a mixture of CeO2 and Al2O3 in evacuated
and sealed quartz tubes at 1200?C for 48 h or
heating the constituent oxides in dynamic vacuum
at 1500?C followed by arc-melting - Heating CeO2 and Al2O3 in diluted hydrogen flow
at 1475?C for 15 h -
J. Am. Ceram. Soc. (communicated)
12Magnetic Property Paramagnetic (100K-300K) Fits
Curie-Weiss model (?p 40K) ?eff 2.2 (Ce3)
pseudo cubic
- It is possible to prepare CeAlO3 using solution
combustion process in oxidizing atmosphere - The magnetic properties are similar to that of
single crystals indicating high quality of
combustion synthesized CeAlO3
13Solution combustion approach for the preparation
of plasma sprayable powders
Ceramics International (in press)
14Plasma sprayable NiO-YSZ anode powder for SOFC
Average agglomerated particle size 10
?m Flowability 40s/50g
Intensity (a.u.)
2? (deg.)
Substrate
Anode coating
To be communicated
15Plasma sprayable La2Zr2O7 powder for TBC
Application
Average agglomerated particle size 12 ?m
Fully melted
To be communicated
Bimodal distribution
16Versatility of SCS
- Decreasing the crystallite size M-fuels
- Decreasing the sintering temperature M-fuels
- Preparation of novel oxides M-fuels
- Preparation of plasma sprayable powders
- --- SOFC application
- --- TBC application
SCS is a Pandoras Box One need to explore
!!!!!!!!!!!!!!
17Why Composite Coatings?
- Various engineering applications - machine
construction and aero-engines - Automobile industry uses electroplated Ni/SiC
for wear protection of cylinder linings and
piston rings. - Lubricant coatings for mechanical process
industries for valves, trajection molds or
sliding contacts - For corrosion protection of steel in automobile
industry - Composite coatings are produced by direct
entrapment of solid particles during the build-up
of the metal matrix - The properties of the coatings are governed by
the type and size of the particle, its content in
the coating and the mode of distribution
18Metal Matrix Nanocomposites
- Metal matrix inert particles are dispersed.
- Uses wear resistance, corrosion resistance,
high-temperature oxidation. - Improved properties compared to plain metal
coatings e.g. higher hardness. - Application aerospace, automotive,
manufacturing and chemical processing. - Ni is strong, tough metal resistant to
corrosion, wear abrasion. - Ni/Ni-Co/Ni-Zn matrix SiC, Al2O3, TiO2.
- Nanocomposites exhibit better wear corrosion
properties.
19Electrodeposition bath conditions
- 50 g/L Ni (300 g/L Nickel sulfamate)
- 10g/l nickel chloride
- 30 g/l boric acid
- 0.2 g/L 10 sodium lauryl sulphate
- Temperature RT
- PH4
- Substratebrass (2.5 cm?3.75 cm)
- Current density 0.23 A/dm2 for 20 h, 0.77 A/dm2
for 6 h,1.55 A/dm2 - for 3 h and 3.1 A/dm2 for 1.5 h
Particles studied PSZ, YSZ, Al2O3, ZTA, AZY,
CeO2, YDC, etc
20Ni/PSZ Ni/YSZ
Average particle size 28.5 nm
Vickers Hardness Ni/YSZ (10 nm) 563-618 Ni/PSZ
(30 nm) 410-430
200 VHN higher hardness for Ni-YSZ
Scripta Materialia 48 (2003) 507512
21Ni/CeO2 Ni/8YDC
YDC
Ni
Ni-YDC
22The corrosion potential, corrosion rates and
Tafel slopes
Surfaces after corrosion
Ni
Ni/8YDC
Ni
J. Appl Electrochem 7 (2007) 991-1000
23Ni-YZA Ni-ZTA composite coatings
Aim To develop a composite coating having higher
microhardness, improved corrosion resistance,
wear resistance and lower friction coefficient
compared to Ni
YZA
J. Alloys Compd. (2008), doi10.1016/j.jallcom.20
08.01.058
24Corrosion Wear resistance Properties of Ni-ZTA
Ni-YZA
Ni-YZA
25Comparison of wear corrosion resistance
properties of Ni composites
icorr (?A cm-2 )
Wear volume (mm3)
Corrosion resistance
Wear resistance
- Wherever engineering components undergo wear and
corrosion problems, Ni-YZA may be used (Patent) - Ni-YZA is also cost-effective
- One can tailor make the composite coatings based
on the application
Indian patent filed 0291NF2005 dt 28th June 2006.
26Preparation and characterisation of Ni-Al2O3
composite coatings
- Plating bath formulation and conditions
- 300 g/L of nickel sulfamate solution (50 g of
Ni/L), 10 g/L of nickel chloride, 30 g/L boric
acid, 0.2 g/L of sodium lauryl sulfate - pH4 Current densities0.23 A/dm2 for 20h, 0.77
A/dm2 for 6h, 1.55 A/dm2 for 3h and 3.1 A/dm2 for
1.5 h
Intensity (au)
(220)-Alcoa
Crystallite size 11 nm
Crystallite size 25 nm
Crystallite size 16 nm
Ni-Al2O3-SCS
Ni-Al2O3-Alcoa
Ni-Al2O3-Co-ppt
27Corrosion results
Zimag (? cm2)
Ni-Al2O3-SCS
Ni-Al2O3-Alcoa
Ni-Al2O3-Co-ppt
Z real (? cm2)
Z real (? cm2)
Z real (?
cm2)
28Ni-Al2O3-Alcoa Ni-Al2O3-Co-ppt Ni-Al2O3-SCS
- CONCLUSIONS
- ??- Al2O3 particles enhanced the
corrosion-resistance of Ni matrix - ?-Al2O3 particles enhanced the wear-resistance of
Ni matrix - Alcoa-Al2O3 did not enhance the corrosion
wear-resistance of Ni matrix
29Conclusions
- Ni-Composite coatings - combustion synthesized
nanoparticles - first time - Ni-CeO2 Ni-8YDC - improved microhardness and
corrosion resistance - Ni-ZTA - improved microhardness and wear
resistance - Ni-YZA - increased microhardness, improved wear
and corrosion resistance - In general combustion synthesized nanosize oxide
powders imparted better properties compared to
commercial powders - Tailor made composites can be prepared
30Acknowledgements
- Prof. K.C. Patil
- Director Head SED, NAL
- CTSM NMITLI (CSIR) for funding
- N. Balaji, NAL
- Dr. N. Kini, Laird technologies
- Mr.V.K.W. Grips, NAL
- Mrs. Ezhil Selvi, NAL (corrosion studies)
- Bindu, Muniprakash, Manikandanath, Dr. R. Rao,
Dr. Anjana, Mr. Venkataswamy-NAL
31Thank You