Improvement of High-Temperature Oxidation of Titanium Alloys by Dipping in a Phosphoric Acid Solution

2008 ◽  
Vol 595-598 ◽  
pp. 17-22 ◽  
Author(s):  
S.Y. Brou ◽  
G. Bonnet ◽  
Jean Luc Grosseau-Poussard
Keyword(s):  
High Temperature ◽  
Phosphoric Acid ◽  
High Temperature Oxidation ◽  
Isothermal Oxidation ◽  
Superficial Layer ◽  
Phosphoric Acid Solution ◽  
Acid Solutions ◽  
Heating Period ◽  
Temperature Oxidation ◽  
Titanium Pyrophosphate

Gamma-TiAl samples were treated by phosphoric acid solutions at different concentrations. With 15 mol/dm3, a viscous deposit was left on the surface leading, after drying and high temperature oxidation, to a very heterogeneous surface aspect. Concentrations below 0.5 mol/dm3 were then used and allowed to greatly ameliorate the homogeneity of the superficial layer. After heating from ambient to oxidation temperature, however, cracks were always observed, due to the departure of gaseous molecules. Isothermal oxidation tests come out at 800°C and 900°C under reconstituted air showed that weight gains were strongly reduced when TiAl had been treated. A compound containing titanium, oxygen and phosphorus was detected at the end of the heating period, identified as titanium pyrophosphate, TiP2O7. This compound remained the only one detected for 100 h when oxidation was come out at 800°C, but evolved towards TiO2 when oxidation time was increased. In the case of oxidation at 900°C, the evolution from TiP2O7 to TiO2 also happened but appeared to go faster.

In situ Raman spectroscopy study on the effect of antioxidants on high temperature oxidation properties of TMPTO

2019 ◽  
Vol 71 (5) ◽  
pp. 706-711 ◽  
Author(s):  
Bingxue Cheng ◽  
Haitao Duan ◽  
Yongliang Jin ◽  
Lei Wei ◽  
Jia Dan ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
High Temperature ◽  
Thermal Oxidation ◽  
High Temperature Oxidation ◽  
Isothermal Oxidation ◽  
In Situ Raman Spectroscopy ◽  
Temperature Oxidation ◽  
Content Type ◽  
Structure Changes ◽  
Oxidation Properties

Purpose This paper aims to investigate the thermal oxidation characteristics of the unsaturated bonds (C=C) of trimethylolpropane trioleate (TMPTO) and to reveal the high temperature oxidation decay mechanism of unsaturated esters and the nature of the anti-oxidation properties of the additives. Design/methodology/approach Using a DXR laser microscopic Raman spectrometer and Linkam FTIR600 temperature control platform, the isothermal oxidation experiments of TMPTO with or without 1.0 wt. % of different antioxidants were performed. Findings The results indicated that the Raman peaks of =C-H, C=C and -CH2- weaken gradually with prolonged oxidation time, and the corresponding Raman intensities drop rapidly at higher temperatures. The aromatic amine antioxidant can decrease the attenuation of peak intensity, as it significantly reduces the rate constant of C=C thermal oxidation. The hindered phenolic antioxidant has a protective effect during the early stages of oxidation (induction period), but it may accelerate the oxidation of C=C afterwards. Originality/value Research on the structure changes of synthetic esters during oxidation by Raman spectroscopy will be of great importance in promoting the use of Raman spectroscopy to analyze the oxidation of lubricants.

Interfacial Kinetics of High Temperature Oxidation in YSZ Thermal Barrier Coatings With Bond Coatings of NiCoCrAlY With 0.25% Hf

2009 ◽  
Author(s):  
Winston Soboyejo ◽  
Patrick Mensah ◽  
Ravinder Diwan
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coatings ◽  
High Temperature Oxidation ◽  
Structural Evolution ◽  
Isothermal Oxidation ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Temperature Oxidation ◽  
Barrier Coatings ◽  
Thermally Grown

This paper presents the results of an experimental study of the high-temperature isothermal oxidation behavior and micro-structural evolution in plasma sprayed thermal barrier coatings (TBCs) at temperatures between 900 and 1200 °C. Two types of specimens were produced for testing. These include a standard and vertically cracked (VC) APS. High temperature oxidation has been carried out at 900, 1000, 1100 and 1200 °C. The experiments have been performed in air under isothermal conditions. At each temperature, the specimens are exposed for 25, 50, 75 and 100 hours. The corresponding microstructures and microchemistries of the TBC layers are then examined using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy EDS. Changes in the dimensions of the thermally grown oxide (TGO) layer are determined as functions of time and temperature. The evolution of bond coat microstructures/interdiffusion zones and thermally grown oxide (TGO) layers are compared in TBCs with standard (STD) and vertically cracked (VC) microstructures.

Properties of Sputtered NiCrAlY Used for Protective Gun Tube Coatings

2011 ◽  
Vol 686 ◽  
pp. 613-617
Author(s):  
Jian Zhang ◽  
Cean Guo ◽  
Gang Zhang ◽  
Chong Rui Wang ◽  
Shi Ming Hao
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Oxidation Process ◽  
Complex Oxide ◽  
Isothermal Oxidation ◽  
Temperature Oxidation ◽  
Steel Balls ◽  
Steel Substrates ◽  
Micro Indentation

NiCrAlY coatings were deposited on CrNi3MoVA steel substrates by means of magnetron sputtering. The coatings were characterized in terms of their microstructure, hardness, friction coefficient, high-temperature oxidation resistance. Micro-indentation and tribometer testers were employed to measure the mechanical properties of NiCrAlY coatings and CrNi3MoVA steel. The results showed that the hardness of the coatings ranged from 5.7 to 5.9 GPa, with a higher value than that of CrNi3MoVA steel(4.1-4.3 GPa). The coefficient of steady-state friction of the coatings against 45-carbon-steel balls ranged from 0.35 to 0.40, with a lower value than that of CrNi3MoVA steel(0.63-0.68). The isothermal oxidation behavior at 850°C of the coatings were studied in comparison with CrNi3MoVA steel substrates. The results indicated that NiCrAlY coatings substantially increase the high-temperature oxidation resistance of CrNi3MoVA steel and the oxidation process was retarded mainly by the presence of outer complex oxide scales and a continuous Al2O3 inner layer on the coating.

The High Temperature Oxidation Behavior of Hot-Dipping Al Coating on 0Cr18Ni10Ti Stainless Steel

2014 ◽  
Vol 905 ◽  
pp. 123-127 ◽  
Author(s):  
Jin Lou ◽  
Jie Ke Wang ◽  
Yu Bin Wang
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
High Temperature Oxidation ◽  
Cyclic Oxidation ◽  
Isothermal Oxidation ◽  
Aluminum Coating ◽  
Diffusion Annealing ◽  
Temperature Oxidation ◽  
Aluminized Steel ◽  
Oxidation Behaviors

0Cr18Ni10Ti stainless steel was coated by hot-dipping in a molten aluminum bath, and then diffusing annealing at 950°C for 2h. The high temperature isothermal oxidation behaviors of the hot-dipped aluminized steel and 0Cr18Ni10Ti steel were tested at 900 °C for 24h using Thermo gravimetric analyzer. The high temperature cyclic oxidation behaviors of the hot-dipped aluminized steel and 0Cr18Ni10Ti steel were tested at 900 °C for 24h using resistance furnace. The morphology was studied by SEM, the phase composition was characterized by EDS. The result of high temperature isothermal and cyclic oxidation test showed that the hot-dipped aluminum can dramatically improve the isothermal and cyclic oxidation of the 0Cr18Ni10Ti steel. The hot-dipping aluminum coating is consists of an outer layer of FeAl and an inner Iron solid solution with aluminum, after diffusion annealing at 950°C for 2 h. The Al2O3 oxide layer was formed on the hot-dipped aluminum coating during isothermal and cyclic oxidation process, which provides an additional protection for the steel from high temperature oxidation.

Research on the Si-Ti High Temperature Oxidation-Resistant Coatings for Tantalum Alloys

2013 ◽  
Vol 785-786 ◽  
pp. 45-51
Author(s):  
Pei Pei Song ◽  
Jun Le ◽  
Feng Ye ◽  
Xiao Cheng Sheng ◽  
Xiao Wei Zhang
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Isothermal Oxidation ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Temperature Oxidation ◽  
X Ray ◽  
Different Temperatures ◽  
Slurry Method ◽  
Sectional Structure

Si-Ti coatings were prepared on the surface of T-222 alloy by fused slurry method at different temperatures (1425-1500°C). Microstructure and composition of the coatings were characterized and analysed through scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), energy dispersive X-ray spectrometry (EDS) respectively. The coating fabricated at 1450°C exhibited excellent structure compatible with high temperature oxidation resistance. Its surface is relatively smooth with few holes and cracks and the main phase on the surface is (Ti, Ta)Si that possesses outstanding corrosion resistance. Moreover, the cross-sectional structure of the coating is smooth and compact which can effectively prevent O2 from permeation. The isothermal oxidation behaviors in pure O2 atmosphere at 1500°C for 2h finally demonstrate that the optimum coating temperature is 1450°C.

Isothermal Oxidation of Sintered β-FeSi2 in Air

2006 ◽  
Vol 522-523 ◽  
pp. 641-648 ◽  
Author(s):  
Makoto Nanko ◽  
Se Hun Chang ◽  
Koji Matsumaru ◽  
Kozo Ishizaki ◽  
Masatoshi Takeda
Keyword(s):  
High Temperature ◽  
Oxide Scale ◽  
Thermoelectric Properties ◽  
High Temperature Oxidation ◽  
Isothermal Oxidation ◽  
Amorphous Sio2 ◽  
Temperature Oxidation ◽  
Parabolic Law ◽  
Before And After ◽  
Significant Change

High-temperature oxidation of sintered β-FeSi2 doped with Mn and Co was evaluated at 800°C in air. Amorphous SiO2 was developed as an oxide scale. Granular ε-FeSi also appeared below the SiO2 scale as a result of consumption of Si in β-FeSi2. Growth of the oxide scale on doped FeSi2 followed a parabolic law and its rate was similar to oxidation of undoped samples. Thermoelectric properties of sintered β-FeSi2 were also evaluated before and after oxidation at 800°C for 7 days. There was no significant change in thermoelectric properties after high-temperature oxidation on β-FeSi2 sintered bodies.

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