Year-2010
http://dspace.iitrpr.ac.in:8080/xmlui/handle/123456789/9
2024-03-29T10:03:22ZTuning the extinction coefficient for direct absorption solar thermal collector
http://dspace.iitrpr.ac.in:8080/xmlui/handle/123456789/2663
Tuning the extinction coefficient for direct absorption solar thermal collector
Otanicar, T. P.; Phelan, P. E.; Taylor, R. A.; Tyagi, H.
Direct-absorption solar thermal collectors have recently
been shown to be a promising technology for photothermal
energy conversion but many parameters affecting the overall
performance of such systems haven’t been studied in depth, yet
alone optimized. Earlier work has shown that the overall
magnitude of the extinction coefficient can play a drastic role,
with too high of an extinction coefficient actually reducing the
efficiency. This study investigates how the extinction
coefficient impacts the collector efficiency and how it can be
tuned as a function of depth to optimize the efficiency, and why
this presents a unique design over conventional solar thermal
collection systems. Three extinction profiles are investigated:
uniform, linearly increasing, and exponentially increasing
2021-09-16T00:00:00ZRole of detonation gun spray Cr3C2–NiCr coating in improving high temperature corrosion resistance of SAE–213–T22 and SAE–347H steel in presence of Na2SO4– 82%Fe2(SO4)3 salt deposits
http://dspace.iitrpr.ac.in:8080/xmlui/handle/123456789/2662
Role of detonation gun spray Cr3C2–NiCr coating in improving high temperature corrosion resistance of SAE–213–T22 and SAE–347H steel in presence of Na2SO4– 82%Fe2(SO4)3 salt deposits
Kaur, M.; Singh, H.; Prakash, S.
Cr3C2–NiCr coatings were sprayed on SAE–213–T22 and SAE–347H boiler steels by detonation
gun spray process. High temperature corrosion studies were conducted on the uncoated as well
as detonation gun sprayed specimens in a molten salt environment at 700uC under cyclic
conditions. The molten salt comprising Na2SO4–82%Fe2(SO4)3 was applied on the specimens as
a deposit. The weight change technique was used to establish kinetics of the corrosion. X-ray
diffraction, field emission scanning electron microscopy/energy dispersive spectroscopy and Xray mapping techniques were used to analyse the corrosion products. SAE–213–T22 steel
suffered an accelerated corrosion in the form of intense spalling of its oxide scale, whereas SAE–
347H steel exhibited only marginal spallation in the form of fine powder. The Cr3C2–NiCr coating
showed good adherence to the boiler steels during the exposure with no tendency for spallation
of its oxide scale. The coating was found to be successful in developing resistance against hot
corrosion in the molten salt environment, which may be attributed to the formation of oxides of
nickel and chromium.
2021-09-16T00:00:00ZRole of CeO2 coating in enhancing high temperature corrosion resistance of Ni-base superalloys as an inhibitor
http://dspace.iitrpr.ac.in:8080/xmlui/handle/123456789/2658
Role of CeO2 coating in enhancing high temperature corrosion resistance of Ni-base superalloys as an inhibitor
Gitanjaly; Singh, H.; Singh, S.; Prakash, S.
Superalloys have been used successfully to resist high temperature corrosion; however, they still lack
resistance to corrosion during longer periods of use. Inhibitors and fuel additives have been used to
reduce corrosion rates with varying degrees of success. In the present investigation, high temperature
corrosion studies were conducted on two Ni-base superalloys, namely Superni 718 and Superni 601,
in a simulated boiler environment (Na2SO4 – 60%V2O5), with and without the presence of a CeO2
coating as an inhibitor. Accelerated corrosion testing was carried out in a silicon carbide tube furnace
under cyclic conditions at 900 C for 50 cycles. Weight change measurements were made after each
cycle. The corroded samples were characterised by SEM, XRD and EPMA techniques. Superni 601
was found to be more corrosion resistant than Superni 718 in the Na2SO4 – 60%V2O5 environment.
The presence of CeO2 in the environment reduced the rate of corrosion of both the alloys, which was
attributed to the presence of unreacted CeO2 on the surfaces of the samples. The presence of a Cr2O3
layer in the oxide scale and a dense, thin Cr2O3 layer at the substrate – scale interface may also be a
contributing factor for the protection of these alloys.
2021-09-16T00:00:00ZCryoprocessing of cutting tool materials - a review
http://dspace.iitrpr.ac.in:8080/xmlui/handle/123456789/2602
Cryoprocessing of cutting tool materials - a review
Gill, S. S.; Singh, H.; Singh, R.; Singh, J.
Cryoprocessing, a supplementary process to
conventional heat treatment process, is the process of
deep-freezing materials at cryogenic temperatures to enhance the mechanical and physical properties of materials
being treated. The execution of cryoprocessing on cutting
tool materials increases wear resistance, hardness, and
dimensional stability and reduces tool consumption and
down time for the machine tool set up, thus leading to cost
reductions. The effects of cryoprocessing on tool steels and
carbides, metallurgical aspects including reduced amount of
retained austenite, precipitation of η-carbides, phase change
in carbides, improvement in wear resistance, and applications are reviewed for manufacturing industry. Although it
has been confirmed that cryogenic processing can improve
the service life of tools, the degree of improvement
experienced and the underlying mechanism remains ambiguous. The steps involved in cryoprocessing are critical
enough to account for the significant incongruity in posttreated performance.
2021-09-02T00:00:00Z