Effect of thickness of oxide film on the emissivity and reflectivity of heat-resistant metals and alloys

1978 ◽  
Vol 34 (1) ◽  
pp. 20-23 ◽  
Author(s):  
G. A. Zhorov ◽  
K. A. Yagunov
Keyword(s):  
Oxide Film ◽  
Metals And Alloys ◽  
Heat Resistant ◽  
Heat Resistant Metals

Investigation of Destruction Mechanisms for Heat-Resistant Coatings in Hypersonic Flows of Air Plasma

2017 ◽  
Vol 269 ◽  
pp. 14-30 ◽  
Author(s):  
Alexey N. Astapov ◽  
Lev N. Rabinskiy
Keyword(s):  
Oxide Film ◽  
Ambient Pressure ◽  
Structural Phase ◽  
Hypersonic Flows ◽  
Oxidation Products ◽  
Protective Film ◽  
Air Plasma ◽  
Main Layer ◽  
Heat Resistant ◽  
Erosion Loss

The authors present the results of investigations of degradation processes that occur in the structure of heat-resistant coating of the Si-TiSi2-MoSi2-B-Y system in hypersonic flows of air plasma. It is found that coating operating capacity at surface temperatures Tw ≤ 1820÷1830°C is provided by the structural-phase state of its microcomposite main layer and formation on the coating surface of a heterogeneous passivating protective film. It is based on borosilicate glass reinforced by rutile microneedles. The mechanism of coating destruction at Tw ≥ 1850÷1860°C is erosion loss of oxide film as well as generation and growth of gas-filled cavities at the "coating main layer–oxide film" interface. As the pressure of saturated vapor of gaseous oxidation products (SiO, CO, MoO3 and B2O3) exceeds that of the ambient, the oxide film integrity is disrupted and oxidation process becomes active. The rates of erosion loss and sublimation grow as operating temperature increases and ambient pressure decreases.

OPERATING CAPACITY OF ANTI-OXIDIZING COATING IN HYPERSONIC FLOWS OF AIR PLASMA

2019 ◽  
Vol 26 (02) ◽  
pp. 1850145 ◽  
Author(s):  
ALEXEY N. ASTAPOV ◽  
EKATERINA L. KUZNETSOVA ◽  
LEV N. RABINSKIY
Keyword(s):  
Oxide Film ◽  
Ceramic Composites ◽  
Hypersonic Flows ◽  
Protective Film ◽  
Air Plasma ◽  
Main Layer ◽  
Operating Capacity ◽  
Heat Resistant ◽  
Wide Range ◽  
Erosion Loss

In this paper, we present the results of investigations of degradation processes that occur in the structure promising high-temperature anti-oxidizing of heat-resistant coating of the Si–TiSi2–MoSi2–B–Y system in hypersonic flows of air plasma. The coating is designed to protect a wide range of heat-resistant materials (carbon–carbon and carbon–ceramic composites, coal–graphite materials, alloys based on Nb, Mo, W, etc.). It is found that the coating operating capacity at surface temperatures [Formula: see text] 1820–1830∘C is provided by the structural-phase state of its microcomposite main layer and formation on the coating surface of a heterogeneous passivating protective film. It is based on borosilicate glass reinforced by rutile microneedles. The mechanism of coating destruction at [Formula: see text] 1850–1860∘C is erosion loss of oxide film as well as generation and growth of gas-filled cavities at the “coating main layer–oxide film” interface. As the pressure of saturated vapor of gaseous oxidation products (SiO, CO, MoO3 and B2O3) exceeds that of the ambient, the oxide film integrity is disrupted and oxidation process becomes active. The rates of erosion loss and sublimation grow as operating temperature increases and ambient pressure decreases.

High-Temperature Oxidation Behaviors of 30Cr25Ni20Si Heat-Resistant Steel in Air

2020 ◽  
Vol 861 ◽  
pp. 83-88
Author(s):  
You Yang ◽  
Xiao Dong Wang
Keyword(s):  
High Temperature ◽  
Oxide Film ◽  
High Temperature Oxidation ◽  
Film Growth ◽  
Surface Oxidation ◽  
Mass Gain ◽  
Resistant Steel ◽  
Temperature Oxidation ◽  
Heat Resistant Steel ◽  
Heat Resistant

High temperature oxidation dynamic behaviors and mechanisms for 30Cr25Ni20Si heat-resistant steel were investigated at 800, 900 and 1000°C. The oxide layers were characterized by scanning electron microscopy (SEM-EDS), X-ray diffractometer (XRD). The results showed that the oxidation rate of test alloys is increased with increasing the oxidation time. The oxidation dynamic curves at 800 and 900°C follow from liner to parabolic oxidation law. The transition point is 10 h. At 1000°C, the steel exhibits a catastrophic oxidation, and the oxidation mass gain value at 50 h is 0.77 mg/cm2. This suggests that the steel at 900°C has formed a dense protective surface oxidation film, effectively preventing the diffusion of the oxygen atoms and other corrosive gas into the alloy. Therefore, at the first stage of oxidation, chemical adsorption and reaction determine the oxide film composition and formation process. At the oxide film growth stage, oxidation is controlled by migration of ions or electrons across the oxide film. When the spinel scale forms, it acts as a compact barrier for O element and improving the oxidation resistance.

scholarly journals Corundum Molds for Investment Casting from Refractory Alloys and Metals

2010 ◽  
Vol 2010 ◽  
pp. 1-5
Author(s):  
P. A. Storozhenko ◽  
G. I. Shcherbakova ◽  
D. V. Sidorov ◽  
M. S. Varfolomeev ◽  
A. S. Murkina
Keyword(s):  
Surface Roughness ◽  
Investment Casting ◽  
High Heat ◽  
Metals And Alloys ◽  
Performance Properties ◽  
Refractory Alloys ◽  
Heat Resistant ◽  
Physical Chemical ◽  
And Performance ◽  
Reactive Metals

Production procedure, physical-chemical, and performance properties of ALUMOX silica-free binder used for the production of high-heat-resistant corundum shell molds by consumable patterns employed in the production of critical molds from superalloyed reactive metals and alloys are described. ALUMOX usage allows obtaining casts from reactive metals and alloys with surface roughness up to  m (basic casts— m), which, in its turn, increases fatigue parameters of the material (endurance, durability).

scholarly journals The refractory compositions designing for the highly-heat-resistant ceramic products in the foundry practice

2018 ◽  
pp. 18-23
Author(s):  
M. S. Varfolomeev ◽  
G. I. Shcherbakova
Keyword(s):  
Ceramic Materials ◽  
Thermal And Mechanical Properties ◽  
Heat Resistant ◽  
Magnesium Compounds ◽  
Different Temperatures ◽  
Bonding Phase ◽  
Heat Resistant Metals ◽  
Α Al2o3 ◽  
Semidry Pressing ◽  
Resistant Ceramic

The sintering peculiarities of the ceramic materials which had been prepared by means of semidry pressing are investigated in the article. The fillers were the yttrium oxide Y2O3 and the fused corundum α-Al2O3, the bonding phase was the aluminoxane addition either pure or modified by the yttrium and magnesium compounds. We investigated the processes occurring at the examined ceramics sintering at different temperatures and their influence on the obtained ceramics properties. The phase composition, the thermal and mechanical properties of the test samples at 1500 °C are presented. The produced test ceramic crucibles have advanced thermal resistance and stability against the thermal cycling. The possibility is regarded to use the developed ceramic crucibles for melting and casting of the chemically reactive highly-heat-resistant metals and alloys.

scholarly journals An Investigation of Accelerated Oxidation of Heat Resistant Metals Due to Vanadium

1955 ◽  
Vol 4 (3) ◽  
pp. 111-114,116
Author(s):  
Forest C. Monkman ◽  
Nicholas J. Grant
Keyword(s):  
Accelerated Oxidation ◽  
Heat Resistant ◽  
Heat Resistant Metals

Predicting creep deformation of heat-resistant metals

1975 ◽  
Vol 7 (7) ◽  
pp. 820-824
Author(s):  
V. I. Kovpak
Keyword(s):  
Creep Deformation ◽  
Heat Resistant ◽  
Heat Resistant Metals

Nanostructure Mechanism of Formation of Oxide Film in Heat-Resistant Fe – 25Cr – 35Ni Superalloys

2015 ◽  
Vol 56 (9-10) ◽  
pp. 531-536 ◽  
Author(s):  
S. Yu. Kondrat’ev ◽  
G. P. Anastasiadi ◽  
A. I. Rudskoy
Keyword(s):  
Oxide Film ◽  
Mechanism Of Formation ◽  
Heat Resistant

Heat-resistant metals in Mendeleev’s periodic table

2012 ◽  
Vol 57 (6) ◽  
pp. 768-772
Author(s):  
N. V. Podberezskaya
Keyword(s):  
Periodic Table ◽  
Heat Resistant ◽  
Heat Resistant Metals
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