Preparation and properties of ZrB2-MoSi2-glass composite powders for plasma sprayed high temperature oxidation resistance coating on C/SiC composites

2019 ◽  
Vol 345 ◽  
pp. 544-552 ◽  
Author(s):  
Si-cong Gu ◽  
Shi-zhen Zhu ◽  
Zhuang Ma ◽  
Shou-peng Han ◽  
Yan-bo Liu
Rare Metals ◽  
2019 ◽  
Author(s):  
Jie Xiao ◽  
Hua-Yue Zhang ◽  
Sheng-Kai Gong ◽  
Hui-Bin Xu ◽  
Hong-Bo Guo

Author(s):  
Zongjun Tian ◽  
Lida Shen ◽  
Zhidong Liu ◽  
Yinhui Huang

In order to further improve the high-temperature oxidation resistance of TiAl intermetallic alloys, MCrAlY coatings were fabricated by plasma spraying and plasma spraying-laser remelting technologies. The microstructures of the as-sprayed and laser-remelted MCrAlY coatings were studied. In addition, the oxidation behaviors at 850 °C for three samples were investigated. One sample is the matrix of TiA1 intermetallic alloys, the other one is processed by plasma-spraying MCrAlY coatings, and the third one is processed by plasma-spraying and laser-remelting MCrAlY coatings. It was revealed that the oxidation resistance of TiAl intermetallics is weak due to lack of protection of Al2O3 film formed on the surface. The plasma-sprayed MCrAlY coatings have better oxidation resistance than the TiAl intermetallics although the plasma-sprayed MCrAlY coatings have high density of porosity and a typical layered structure. It is demonstrated that most of the holes can be eliminated by laser remelting, leading to the best oxidation resistance of the third sample with the laser-remelted coatings. The high oxidation resistance of the laser-remelted coatings is mainly attributed to three aspects: firstly, an Al enriched zone on the coating surface is formed during laser remelting, which is transformed into a protective Al2O3 film during oxidation process. Secondly, laser remelting eliminates most of the defects in plasma-sprayed coatings and enhances its density, thus decreases the channel of oxidation diffusion in high temperature oxidation process. Thirdly, rapid cooling of laser remelting results in a grain refinement and a preferred oxidation of Al at the initial stage, leading to a reduction of oxidation rate.


2006 ◽  
Vol 509 ◽  
pp. 129-134
Author(s):  
U. Arce-Colunga ◽  
F.A. Reyes-Valdes ◽  
A. Martínez-Villafañe ◽  
Victor M. Orozco-Carmona ◽  
F. Almeraya-Calderón ◽  
...  

The high temperature oxidation resistance of Cr-ZrO2-Al2O3 composites fabricated by mechanical alloying and spark plasma sintering (SPS) has been evaluated. Composite powders were prepared by ball milling Cr-5vol%ZrO2-50vol%Al2O3 powder mixtures. Powders were compacted by SPS in less than 5 min, so that a particular metal-ceramic interpenetrating network is obtained. High temperature oxidation tests (900-1100 0C) in air have revealed good oxidation resistance (1.8, 2.6 and 15.3 mg/cm2 at 900, 1000 and 1100 °C, respectively) due to a protective Cr2O3 layer. EDX analysis revealed that Cr diffusion takes place at 1100 oC from the bulk towards the composite surface leading to Cr depletion at near-surface zones. Chromium contained in the bulk tends to oxidize through oxygen diffusion apparently occurring along the grain boundaries.


2010 ◽  
Vol 34-35 ◽  
pp. 1876-1880
Author(s):  
Fei Chen ◽  
Hai Zhou ◽  
Jia Qing Chen ◽  
Fan Xiu Lu

The plasma sprayed gradated coating with the bottom layer of NiCrAlY and the top layer of (ZrO2+CaO) was prepared on the 1Cr18Ni9Ti steel surface by the plasma spraying technique. The phase structure and morphology of the gradated coating were analyzed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The high temperature oxidation resistance of the plasma sprayed samples at 800°C was investigated. The oxidation kinetics curve was worked out. The wear-resistance behavior of the graduated coating under dry sliding against GCr15 steel was evaluated on a ball-on-disc test rig. The results show that the thickness of gradated coating is about 320μm. The plasma sprayed gradated coating on stainless steel surface can improve the high temperature oxidation resistance of stainless steel. The oxidation rate of stainless steel is less than that of plasma sprayed gradated coating. The oxidation coating of plasma sprayed sample was very dense and is not easily exfoliated. The dense oxidation coating prevents the stainless steel from more oxidation. The friction coefficient of the 1Cr18Ni9Ti substrate was about 0.33 on dry sliding against the GCr15 steel, while the graduated coating experienced abated friction coefficient to 0.21 on the same testing condition.


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