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Journal of Materials Science and Nanotechnology | Volume 3
October 07-08, 2019 | Frankfurt, Germany
Materials Science and Engineering
3
rd
International Conference on
Mater Sci Nanotechnol, Volume 3
T
he microstructure and high-temperature oxidation-
resistant performance of four silicide coatings prepared
respectively at 1250°C for 8 h by pack siliconizing process,
Si-Y co-deposition process and Si-Al-Y co-deposition process
(with different Al contents in the packs) on an Nb-Si based
alloy were revealed. The results showed that the purely
siliconized coating was composed of a (Ti,Nb)5Si
3
ouer layer,
a (Nb,X)Si
2
(X represents Ti, Cr and Hf elements) middle layer
and a (Ti,Nb)5Si
4
inner layer. A thicker and more compact
double-layer structure including a (Nb,X)Si
2
outer layer and a
(Ti,Nb)5Si
4
inner layer was observed in the Si-Y co-deposition
coating. In addition, a higher Y content (about 0.34 at. %)
in the outer layer of the Si-Y co-deposition coating was
obtained, while the Y content was only about 0.06 at. % in the
purely siliconized coating. The Si-Al-Y co-deposition coating
possessed a (Nb,X)Si
2
outer layer, a (Ti,Nb)5Si
4
middle layer
and an Al, Cr-rich inner layer. A suitable addition of Al powders
(5 wt. %) in the packs was beneficial to thicken the (Nb,X)Si
2
outer layer, while a sharp reduction in the coating thickness
was found when excess Al powders (10 wt. %) was added
in the packs. The thickness and microstructure of the scales
formed on above four coatings upon oxidation at 1250°C
for either 5 h or 100 h were comparatively investigated.
The oxidation resistance of these silicide-type coatings was
notably enhanced by the addition of Y and Al. The Si-Al-Y
co-deposition coating prepared with 5 wt. % Al powders in
the pack, possessed the best oxidation resistance due to its
optimum dense and continuous scale and compact coating
remained.
Speaker Biography
XipingGuohascompletedhisPhD in1992fromNorthwesternPolytechnical
University,China.HeistheprofessorofNorthwesternPolytechnicalUniversity,
China. His research interests are in the fields of ultrahigh temperature
structural metallic materials, oxidation resistant coating technologies
and directional solidification techniques. He has over 260 publications
that have been cited over 1300 times, and his publication H-index is 20.
e:
xpguo@nwpu.edu.cnXiping Guo
Jing Li
Northwestern Polytechnical University, China
Microstructure and high-temperature oxidation-resistant
performance of four silicide coatings on Nb-Ti-Si based alloy
prepared by pack cementation process