scholarly journals Oxidation Behavior of Multilayer Hard Coatings (TiCN/Al2O3/TiN) in Process of Recycling Coated Multicomponent Hardmetal Scrap

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1796 ◽  
Author(s):  
Hai Kuang ◽  
Dunqiang Tan ◽  
Wen He ◽  
Zhiqiang Yi ◽  
Zhihang Zou ◽  
...  
Keyword(s):  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Hard Coatings ◽  
Hard Alloys ◽  
Al2o3 Layer ◽  
Good Oxidation Resistance ◽  
Element Diffusion ◽  
Negative Effect ◽  
Al2o3 Phase

The coating is one of the biggest problems in the recycling of coated multicomponent hardmetal scraps. The isothermal oxidation behavior of WC-Co multicomponent cemented carbide inserts with a TiCN/Al2O3/TiN hard coating in the recycling process was investigated. The oxidation rate slowed down as the protective coating blocked element diffusion. A rapid oxidation rate was obtained when they were milled into powders and isothermally oxidized at 900 °C. A rapid path for element diffusion was provided by the defects, which were promoted by stress, expansion, and gas volatilization. Both the TiN and TiCN layers were oxidized to a porous TiO2 scale, while the Al2O3 phase remained and the dense Al2O3 layer acted as a barrier for its good oxidation resistance. Pieces of the Al2O3 layer were obviously seen in the final oxides. This provides critical information to reduce the negative effect of coatings and improve the performance of recycled WC powders and hard alloys.

Oxidation Behavior of K38 Superalloy with Different Amounts of Yttrium Addition at 1173K in Air

2011 ◽  
Vol 366 ◽  
pp. 40-44 ◽  
Author(s):  
Ping Yu ◽  
Long Shi ◽  
Wen Wang ◽  
Fu Hui Wang
Keyword(s):  
Oxidation Resistance ◽  
Selective Oxidation ◽  
Internal Oxidation ◽  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Rich Phase ◽  
Al2o3 Scales ◽  
Yttrium Addition ◽  
Negative Effect ◽  
Cast Alloys

The oxidation behavior of K38 alloy with 0, 0.05, 0.1, 0.5wt% yttrium concentrations has been investigated during exposures in air at 1173K for 100 hours. The results indicated that Cr2O3 and TiO2 scale mainly formed on the surface of the alloy without yttrium. Yttrium addition promoted the selective oxidation of aluminum and reduced the internal oxidation. The alloy with 0.1 wt.% yttrium addition exhibits excellent oxidation behavior among the four types of the alloys for its decreasing the oxidation rate and forming more continuous and compact Al2O3 scales. Yttrium-rich phase formed in the alloy with 0.5wt.% yttrium, result in a negative effect on the oxidation resistance of cast alloys.

Isothermal Oxidation Behavior of Ni Base Superalloy DM02 for High Temperature Dies

2007 ◽  
Vol 546-549 ◽  
pp. 1253-1256
Author(s):  
Qing Li ◽  
Jin Xia Song ◽  
Cheng Bo Xiao ◽  
Shi Yu Qu ◽  
Ding Gang Wang ◽  
...  
Keyword(s):  
Weight Gain ◽  
High Temperature ◽  
Oxide Scale ◽  
Oxidation Resistance ◽  
Growth Mechanism ◽  
Oxidation Kinetics ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Good Oxidation Resistance ◽  
Base Superalloy

The isothermal oxidation behavior of a new developed Ni base superalloy named DM02 for high temperature dies was studied in this paper. The dynamic curve was achieved by monitoring weight gain of the alloy as a function of time. The results showed that the alloy had fairly good oxidation resistance at 1050°C and 1100°C. The oxidation kinetics at both 1050°C and 1100°C followed parabolic rules in segment. It has been found that the oxidation of the alloy was controlled by multi-oxides of (Ni, Co)O, (Ni, Co)Al2O4, and NiWO4, growth mechanism in the primary stage, and by Al2O3, NiAl2O4 growth mechanism in the following stage. After oxidation at 1050°C for 100h, the oxide scale of the alloy was mainly composed of two areas. Some were thin uniform (Ni， Co)Al2O4(outer)/Al2O3 (inner) composites scale and others were multi-layer oxide scale of ( Ni,Co)O / multi-oxides (mainly NiWO4、NiO and NiAl2O4.) /Al2O3.

Element diffusion during fabrication of EB-PVD NiAl coating and its 1100 °C isothermal oxidation behavior (II)

2007 ◽  
Vol 201 (15) ◽  
pp. 6589-6592 ◽  
Author(s):  
Hefei Li ◽  
Shufeng Tao ◽  
Zhaohui Zhou ◽  
Lidong Sun ◽  
Hesnawi.A ◽  
...  
Keyword(s):  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Element Diffusion

Isothermal Oxidation Behavior of AlN-TiB2 Ceramics Synthesized by SHS-HIP

2013 ◽  
Vol 575-576 ◽  
pp. 170-173
Author(s):  
Li Juan Zhou ◽  
Yun Xia Zhao ◽  
Hong Bo Li ◽  
Yong Ting Zheng ◽  
Fan Tao Meng
Keyword(s):  
High Temperature ◽  
Oxidation Behavior ◽  
Hot Isostatic Pressing ◽  
Isothermal Oxidation ◽  
Oxidation Products ◽  
Aluminum Borate ◽  
Temperature Synthesis ◽  
Good Oxidation Resistance ◽  
High Temperature Synthesis ◽  
Conductive Ceramics

sothermal oxidation behavior of the AlN-TiB2 conductive ceramics prepared by self-propagating high-temperature synthesis and hot isostatic pressing (SHS-HIP) was evaluated in a temperature range from 900 to 1400 °C for exposure times from 1 to 16 h in air. The oxidation experimental results show that the conductive ceramics have a good oxidation resistance below 1200 °C. The oxidation products on the sample surfaces are mainly composed of Al2TiO5, TiO2 and aluminum borate phases.

Improvement of Oxidation Resistance of A NiAl Eutectic Alloy Doping with Dy

2010 ◽  
Vol 34-35 ◽  
pp. 1263-1268
Author(s):  
Guang Ye Zhang ◽  
Jin Lin Wang ◽  
You Ming Chen ◽  
Long Fei Liu ◽  
Yuan Jun Guo
Keyword(s):  
Oxidation Resistance ◽  
Eutectic Alloy ◽  
Transition Layer ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Al2o3 Layer

The isothermal oxidation behavior of NiAl-30.9Cr-3Mo-0.1Dy alloy has been investigated in the paper. The results reveal that Dy-addition significantly improves the oxidation resistance, which is attributed to the formation of continuously compact Al2O3 layer and rich-Cr transition layer on the surface of the tested alloy.

scholarly journals Investigation on Optimal Ta/Cr Ratio of a Single Crystal Ni-Base Superalloy in View of the Isothermal Oxidation Behavior

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1421
Author(s):  
Jianxiu Chang ◽  
Wenhao Feng ◽  
Wenwen Zhao ◽  
Hongmin Jia ◽  
Yanming Liu ◽  
...  
Keyword(s):  
Single Crystal ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Nitride Layer ◽  
Oxidation Products ◽  
Competitive Growth ◽  
X Ray Diffraction ◽  
Al2o3 Layer ◽  
Oxidation Performance

The relative content of strengthening element tantalum (Ta) and oxidation-resistant element chromium (Cr) is an essential value for superalloys to obtain an excellent combination of oxidation resistance and mechanical properties. In the present paper, the isothermal oxidation behavior of several single crystal Ni-base superalloys with different Ta/Cr (wt. %, similarly hereinafter) ratios at 1000 °C in static air has been systematically investigated to explore the optimal Ta/Cr for excellent oxidation resistance. A detailed microstructure study using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and an electro-probe microanalyzer (EPMA) was performed to reveal the oxidation products and mechanisms. For all alloys, a three-layer structured scale consisting of an outer (Cr, Al, Ti, Ni, Ta)-O layer, an inner Al2O3 layer and an inner nitride layer was formed. As Ta/Cr increased, the amounts of Ta-containing products, cracks, holes and inner nitride increased. Meanwhile, the completeness of the Al2O3 layer got worse. It was shown that if Ta/Cr ≤ 0.5, Ta increased the growth rate of Cr2O3 via the doping effect induced by Ta cations. If Ta/Cr > 0.5, Ta reduced the completeness of Cr2O3 through competitive growth of Ta2O5 and Cr2O3. A good oxidation performance can be expected with the value Ta/Cr ≤ 0.5.

scholarly journals Effect of Y on the Oxidation Behavior of a Directionally Solidified Ni-based Single Crystal Superalloy

2020 ◽  
Author(s):  
Zihan Zhao ◽  
Kai Guan ◽  
Renjie Cui ◽  
Jianchao Qin ◽  
Zhaohui Huang
Keyword(s):  
Weight Gain ◽  
Single Crystal ◽  
Oxide Scale ◽  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Oxidation Products ◽  
Single Crystal Superalloy ◽  
Directionally Solidified ◽  
Oxidation Weight Gain

Abstract The effect of Y addition on the oxidation behavior of a Ni-based directionally solidified single crystal superalloy was investigated. Isothermal oxidation test for the samples with different-level Y addition was conducted at 1100℃ in air. The Y content of the samples was demarcated by the actual pickup amount resulted from ICP-AES test. It was found that the addition of Y increased the oxide resistance by an adhesive double-layer oxide scale which was composed of Al2O3 and spinel Ni(Cr,Al)2O4. With 70ppm Y addition, the oxidation weight gain was decreased from 12.6g/m2 for the alloy without Y addition to 5.3g/m2, and the oxidation rate was significantly decreased. Besides, the internal nitride also disappeared after Y doping because of the increasing oxidation scale adherence and the decreasing of oxidation products. In this study, 660ppm Y addition alloy showed the best oxidation resistance.

Oxidation Behavior of Pt+Hf-Modified γ-Ni +γ'-Ni3Al Alloys

2006 ◽  
Vol 522-523 ◽  
pp. 221-228 ◽  
Author(s):  
Takeshi Izumi ◽  
Brian Gleeson
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Al2o3 Layer ◽  
Cross Sectional ◽  
Good Oxidation Resistance ◽  
Beneficial Effects ◽  
Nial Alloy ◽  
Oxide Spallation ◽  
Co Addition ◽  
Α Al2o3

The oxidation behavior of Pt+Hf-modified γ-Ni+γ′-Ni3Al alloys containing up to 20 at.% Pt and either 15 or 20 at.% Al was studied by oxidizing the alloys in air at 1150°C under both isothermal and thermal cycling conditions. It was found that the co-addition of Pt and Hf was extremely beneficial to oxidation resistance, to the extent that Ni-20Al-20Pt-Hf and Ni-20Al-10Pt-Hf alloys (all compositions are in at.%) oxidized at significantly slower rates than that of a Ni-50Al-15Pt β-NiAl alloy. A Ni-20Al-5Pt-Hf alloy also showed good oxidation resistance, with the steady-state oxidation rate being almost the same as that obtained for the β alloy. Over a period of up to 500 one-hour oxidation cycles, no oxide spallation from the modified γ+γ′ alloys was observed. From cross-sectional SEM examination coupled with X-ray diffraction analyses, it was found that a compact and planar exclusive scale layer of α-Al2O3 formed on the Ni-20Al-20Pt-Hf alloy. By contrast, the Ni-20Al-10Pt-Hf and Ni-20Al-5Pt-Hf alloys formed a very thin outer layer of NiAl2O4 and a planar inner layer of α-Al2O3. The thickness of the inner Al2O3 layer increased with increasing oxidation time relative to that of the NiAl2O4 layer, meaning that the latter primarily formed during the initial stages of scale formation. Both NiO and NiAl2O4 were found in the scales formed on the Ni-20Al-Hf and Ni-15Al-0~10Pt-Hf alloys, with the thickness of these oxide layers decreasing with increasing Pt content in the alloys. Further, it was found that the extent of internal HfO2 formation decreased significantly with increasing Pt content, to the extent that no HfO2 was found in the oxidized Ni-20Al-20Pt-Hf alloy. Inferences for the observed beneficial effects of Pt promoting protective Al2O3 formation and decreasing the tendency for Hf to oxidize in γ+γ′ alloys are discussed.

Effect of the Amorphous Silica Coating Derived by Sol-Gel Processing on the Oxidation Behavior of Ni

2009 ◽  
Vol 79-82 ◽  
pp. 671-674
Author(s):  
B.Y. Ren ◽  
Y.H. Gao ◽  
S.J. Wang ◽  
X.J. Zhang ◽  
N.X. Feng
Keyword(s):  
Thin Film ◽  
Amorphous Silica ◽  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Sol Gel ◽  
Silica Coating ◽  
Isothermal Oxidation ◽  
Dip Coating ◽  
Silica Sol ◽  
Gel Processing

Amorphous silica coating was deposited on the surface of Ni by dip-coating processing from commercial silica sol. Isothermal oxidation of the coated and uncoated specimens at 973 K to 1173 K in air was conducted to investigate the effect of the silica coating on the oxidation behavior of Ni by TGA, SEM and XRD. Results of the oxidation tests showed that the oxidation rate of Ni was reduced greatly due to the applied thin film. The possible mechanism of the effect of thin film on the oxidation of Ni was discussed.

Fabrication and Isothermal Oxidation Behavior of the Co-Deposited EB-PVD (NiAl + YSZ) Coating

2007 ◽  
Vol 336-338 ◽  
pp. 1767-1769
Author(s):  
Sheng Kai Gong ◽  
He Fei Li ◽  
Hesnawi A ◽  
Kuo Jiang ◽  
Li Dong Sun
Keyword(s):  
Bond Coat ◽  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Bond Coatings ◽  
Ysz Coating

The influence of YSZ addition on isothermal oxidation behavior of EB-PVD NiAl bond coatings on Ni based superalloy was investigated. The oxidation rate of the YSZ doped bond coat is almost the same as the bond coat without the doping of YSZ. Four different areas exist on the surface of the coating after 100 h oxidation, including the spalled area, the high Al-contained area, the high Cr&Ni-contained area and the high Ti-contained area.

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