Thermal Shock Resistance of Plasma-Sprayed Ceramic Coatings With Two- and Three-Layers

Author(s):  
Y.-G. Kweon ◽  
H.-J. Kim

Abstract Several plasma-sprayed ceramic coatings with two- and three-layers were characterized and tested for the application of cooling tube coatings at the steel making factory. Thermal cycling tests using a torch heating with compressed air cooling were carried out and characterized before and after the tests. The effects of bond coat as well as top coat were also studied. Possible failure mechanisms with low carbon steel substrate were assessed in term of microstructure, porosity, bond strength, thermal expansion coefficient, and the phase transformation. Finally, the results of field tests at the oxygen convert gas recovery system are also discussed.

2007 ◽  
Vol 345-346 ◽  
pp. 641-644 ◽  
Author(s):  
Jee Hoon Ahn ◽  
Eun Pil Song ◽  
Sung Hak Lee ◽  
Nack J. Kim

Wear resistance of Al2O3-8wt.%TiO2 coatings plasma-sprayed using nanopowders was investigated. Four types of nanostructured Al2O3-8wt.%TiO2 powders were plasma-sprayed on a low-carbon steel substrate by using different critical plasma spray parameters (CPSP). The coatings consisted of completely melted and partially melted regions. The hardness of the coatings increased with increasing CPSP, while the wear resistance was the highest for the coating sprayed with the lowest CPSP. The main wear mechanism was a delamination mode in the coating sprayed with the high CPSP, but was changed to an abrasive mode in the coating sprayed with the low CPSP. According to this change in the wear mechanism, the wear resistance was the best in the coating sprayed with lowest CPSP, while its hardness was lowest.


2013 ◽  
Vol 734-737 ◽  
pp. 2269-2272
Author(s):  
Hong Mei Zhu ◽  
Shu Mei Lei ◽  
Tong Chun Kuang

In this paper, a low carbon steel was used as the substrate to prepare the carbon nanostructural materials by the oxygen-acetylene flame method. The experimental results show that the composite products including nodular carbon nanoparticles and amorphous carbon were obtained on the substrate after a mechanical polishing pretreatment. Comparatively, the short tubular carbon nanofibers with the diameter of around 100 nm were deposited on the substrate pretreated by dipping in the concentrated nitric acid solution. The possible mechanism for the growth of such carbon nanofibers was discussed.


2021 ◽  
Vol 886 ◽  
pp. 168-174
Author(s):  
Mohanad N. Al-Shroofy ◽  
Hanna A. Al-Kaisy ◽  
Rabab Chalaby

Powder spray coating was used for many applications such as paint decoration and protection against corrosive environments. The electrostatic spray method is used to lower the manufacturing cost and the environmental effect during the production process. It is done by electrostatic device and spray gun to create a layer on the substrate to play a protective role. Different dry powders were mixed to form a composite mixture consisted of Al2O3 and SiC or ZrSiO4 with Al powder as a binder. The powders mixture was deposited by electrostatic spray technique with a high voltage of 15 kV on a low carbon steel substrate of (40 x 10 x 4) mm in dimensions. Two groups of mixtures were used to form the coating layers. Powders of Al2O3 with (20 and 40) weight percent (wt%) of SiC as the first group and (20 and 40) wt% of ZrSiO4 as the second group were used. 5 wt% of Al powder was added as a binder, and the samples were heat treated at 900 C° for 2 hours. A detailed characterization of the composite coating layers was performed using XRD, SEM, and EDX, as well as, micro-hardness measurements. The obtained surface composite layers were smooth and having good particle distribution which leads to enhance roughness values (Ra). Furthermore, the hardness increased with increasing the amount of carbide and zirconia, and the obtained layers show no presence of defects or cracks.


2016 ◽  
Vol 286 ◽  
pp. 383-387 ◽  
Author(s):  
S. Mohammadkhani ◽  
E. Jajarmi ◽  
H. Nasiri ◽  
J. Vahdati-Khaki ◽  
M. Haddad-Sabzevar

Author(s):  
V. V. Savinkov ◽  
I. A. Kovaleva

With the aim of obtaining scale with a high degree possibility of mechanical removal under the conditions of the section rolling shop No. 1, at the mill «150» JSC «Belarusian Metallurgical Works – Management Company of Holding «BMC» developed technological modes of production of wire rods made of low-carbon steel grades.The peculiarities of scale formation were studied, namely, the factors influencing the removability, obtaining the optimal thickness and its phase components on the wire rod diameter 5.5–6.5 mm in the cooling process immediately after rolling, intended for wire production.To obtain the necessary ratio of the phase constituents of the scales on the surface of the wire rod, the following factors was taken into account: the temperature of the layout of the turns on the roller table in the air cooling line; (uniformity along the length of the turn), the cooling conditions of the helix of the turns (prevention of the 4FeO = Fe3O4-Fe decay), where the condition of cooling the wire rod from 600 to 250 °С, not exceeding 100 s, must be observed.The results of metallographic studies of scale on the wire surface are presented. The introduced technological regimes provided the optimal thickness and the FeO / Fe3O4 ratio after the experimental rolling of the metal. Exhausted cooling regimes allowed to reduce the consumption of fiber for all types of wire.


1992 ◽  
Vol 52 (2) ◽  
pp. 141-144 ◽  
Author(s):  
Wang Aihua ◽  
Tao Zengyi ◽  
Zhu Beidi ◽  
Fu Jiangmin ◽  
Ma Xianyao ◽  
...  

2012 ◽  
Vol 57 (2) ◽  
pp. 517 ◽  
Author(s):  
M. Żelechower ◽  
J. Kliś ◽  
E. Augustyn ◽  
J. Grzonka ◽  
D. Stróż ◽  
...  

The Microstructure of AnnealedGalfanCoating on Steel SubstrateThe commercially availableGalfancoating containing 5-7wt.% of Al deposited on the low carbon steel substrate by hot dipping has been examined with respect to the microstructure of the coating/substrate interface area. The application of several experimental techniques (SEM/EDS, XRD, TEM/AEM/EDS/ED) allowed demonstrating the two-phase structure of the alloy coating in non-treated, commercially availableGalfansamples: Zn-rich pre-eutectoidηphase grains are surrounded by lamellar eutectics ofβ-Al andη-Zn. The transition layer between the alloy coating and steel substrate with the considerably higher Al content (SEM/EDS, TEM/EDS) has been found in both non-treated and annealed samples (600°C/5 minutes). Only the monoclinic FeAl3Znxphase however was revealed in the annealed sample (TEM/electron diffraction) remaining uncertain the presence of the orthorhombic Fe2Al5Znxphase, reported by several authors.


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