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Hei Y.,Qiqihar Northern Machine Co. | Chen R.,China North Engine Institute | Song B.,Beijing Beifang Hengli Technology Development Co.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2011

Through CASTsoft CAD/CAE technology calculating casting billet modulus, processing hot spot, gating-riser system, filling and solidification, processing design and possible defects in the castings were analyzed. Based on analyzed results, the optimized design was presented. The results show that the numerical simulation can effectively reduce or eliminate possible defects, decreasing trial-production process, improving the reliability of the technology.


Gao P.H.,Xi'an Technological University | Li J.P.,Xi'an Technological University | Yang Z.,Xi'an Technological University | Guo Y.C.,Xi'an Technological University | And 4 more authors.
Applied Mechanics and Materials | Year: 2013

In this paper, MCrAlY bonding layer was prepared through high velocity-oxygen fuel spray on the AZ91 magnesium alloy surface. 8wt%YSZ ceramic layer was deposited on the surface of bonding layer through atmospheric plasma spraying. The coatings were characterized by XRD and SEM. The hardness of the coating was tested. The coefficients of thermal expansion of the coating were measured through TMA. It was found that there were un-melted 8YSZ particles surrounded by melted particles layer by layer. Parts of ZrO2 transited from cubic to tetragonal. The microhardness of the YSZ coating and bonding layer were 832.1Hvo.3 and 700.3Hvo.3, respectively. The coefficients of thermal expansion of the magnesium alloy, MCrAlY layer and YSZ coating were 42.46 x 10-6 k-1, 15.26 x 10-6 k-1, 9.28x 10-6 k-1, respectively. The bonding coat matched the magnesium alloy substrate and the YSZ coating well. The dimension of AZ91 magnesium alloy sample was very stabilized before and after coating deposition. © (2013) Trans Tech Publications, Switzerland.


Gao P.,Xi'an Technological University | Li J.,Xi'an Technological University | Yang Z.,Xi'an Technological University | Guo Y.,Xi'an Technological University | Wang Y.,China North Engine Institute
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2015

Al/SiC composite coatings were deposited on the surface of aluminum alloy by atmospheric plasma spraying. The effects of SiC volume in Al/SiC composite powders on the deposition behavior and the properties of the Al/SiC coatings were investigated. It is found that the decarburization and oxidation of pure SiC powder occur in the plasma flame. With the increase of SiC content, the deposition of the Al/SiC composite powder becomes more difficult through plasma spraying. There exist cracks between the bond coat and the aluminum alloy substrate resulting in poor adhesion between them. The hardness of the composite coating becomes higher with the increase of SiC content. The Al/SiC (50:50) deposit with a thickness of 70 μm and a hardness of 3690 MPa can strengthen the surface of aluminum alloy. Copyright © 2015, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.


Gao P.H.,Xi'an Technological University | Li J.P.,Xi'an Technological University | Yang Z.,Xi'an Technological University | Guo Y.C.,Xi'an Technological University | Wang Y.R.,China North Engine Institute
Materials Science Forum | Year: 2013

In this study, Al-12Si alloy coatings with different thickness were prepared through flame spray on the surface of the AZ91 magnesium alloy to improve its corrosion resistance. The corrosion resistance was characterized through corrosion potential using electrochemical methods. The Al-12Si alloy coatings were heat treated at 100 °C, 200 °C and 300 °C for 6, 12, 18 and 24 hours. The effects of heat treatment temperature and time on the coatings' corrosion resistance were discussed. It was found that there were no phase changes during the deposition of Al-12Si coatings through flame spray and heat treatment. The greater the coating thickness was, the higher the corrosion potential was. After annealing, the inner microstructure of the Al-12Si coating was densified furtherly and the annealed coatings had higher corrosion potential and better corrosion resistance. The coating annealed at 100 °C for 18 hours had the highest corrosion potential and the best corrosion resistance in the same coating thickness. © (2013) Trans Tech Publications, Switzerland.


Gao P.-H.,Xi'an Technological University | Cao S.-T.,Xi'an Technological University | Li J.-P.,Xi'an Technological University | Yang Z.,Xi'an Technological University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2016

M42C stainless steel coatings were deposited on the surface of cast iron through atmospheric plasma spray with different plasma arc powers of 30 kW, 35 kW and 40 kW to obtain higher oxidation resistance than that of cast iron. The high temperature oxidation tests were carried out at 400 °C, 530 °C and 700 °C. It was found that the oxidation mass gains of the M42C coatings were much lower than those of cast irons during initial oxidation. With the increase of oxidation temperature and time, the oxidation mass gains of cast irons increased much more quickly than those of the M42C coatings. At 400 °C and 530 °C, the oxidation mass gains of the M42C coatings were higher than that of the M42C bulk. When the temperature reached 700 °C, the oxidation mass gains of the M42C coatings were just a little higher than that of the M42C bulk. Chromite spinel FeCr2O4 were formed which could hinder the further oxidation in the M42C coating. During the service of the M42C coatings at 700 °C, the oxidation resistance of the M42C coating was increased to the level close to that of the bulk. © 2016 Elsevier B.V. All rights reserved.

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