Pest Resistant and Low CTE MoSi2-Matrix for High Temperature Structural Applications

1994 ◽  
Vol 350 ◽  
Author(s):  
M. G. Hebsur
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Matrix Composition ◽  
Temperature Oxidation ◽  
Accelerated Oxidation ◽  
Structural Applications ◽  
Base Matrix ◽  
Sic Reinforcement

AbstractThe objective of this investigation was to identify a pest resistant MoSi2-base matrix composition having properties suitable for SiC reinforcement. A 30 vol.% addition of fine Si3N4 particulates to MoSi2 significantly improved the low temperature accelerated oxidation resistance and thereby eliminated pest failure. Addition of Si3N4 also improved the high temperature oxidation resistance, strength and more importantly lowered the CTE of MoSi2 such that cracking was eliminated in a hybrid composite consisting of 30 vol.% Si3N4 and 30 vol. % SCS-6 fibers.

The Investigation of the Interdiffusion Barrier in TiAl/MCrAlY System

2010 ◽  
Vol 654-656 ◽  
pp. 1920-1923 ◽  
Author(s):  
Wen Wang ◽  
Yu Xian Cheng ◽  
Sheng Long Zhu ◽  
Fu Hui Wang ◽  
Li Xin
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Diffusion Barrier ◽  
High Temperature Oxidation ◽  
Temperature Oxidation ◽  
The Poor ◽  
Structural Applications ◽  
Nicraly Coating ◽  
Overlay Coatings ◽  
Poor Oxidation Resistance

TiAl based alloys are promising candidates for structural applications at high temperature. However, the poor oxidation resistance above 800oC obviously restrains their applications. Although NiCrAlY overlay coatings can remarkably improve the high temperature oxidation resistance of TiAl, serious inward diffusion of Ni from the coating to the substrate occurs which could reduce the lifetime of the coating/substrate system. Apparently, the development of interdiffusion barrier could overcome the disadvantage of the NiCrAlY/TiAl system. In this work, Ta, TiN and Cr2O3 interlayers were deposited between NiCrAlY coating and γ-TiAl substrate as diffusion barrier (DB). The interdiffusion behavior of the TiAl/DB/NiCrAlY system was investigated at 1000°C. The results showed that the metallic and nitride interlayers cannot retard the interdiffusion of Ni effectively. As an active diffusion barrier, the oxide interlayer obviously suppressed the inward diffusion of Ni from the coating to the substrate by the formation of alumina-rich layers at both the TiAl/DB and DB/NiCrAlY interfaces.

Electron Probe Microanalysis (EPMA) Characterization of Scales Formed on Laves Phase Reinforced Cr Alloys at 1100°C in Air

1999 ◽  
Vol 5 (S2) ◽  
pp. 852-853
Author(s):  
L.R. Walker ◽  
M.P. Brady
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Complex Mixture ◽  
Laves Phase ◽  
Temperature Oxidation ◽  
Heat Treated ◽  
Structural Applications ◽  
Temperature Fracture

Laves phase (Cr2X) strengthened Cr solid solution [Cr(X)]-based alloys are under development for a variety of high-temperature structural applications. Among the most promising alloys are castings based on the Cr(Ta)-Cr2Ta eutectic, which exhibit room-temperature fracture toughness in the 10-12 MPa√m range and creep rupture lives in excess of 1000 h at 1000° (138 MPa) in air. These alloys exhibit superior high-temperature oxidation resistance to previously developed Cr(Nb)-Cr2 Nb based alloys despite the general similarities of Ta and Nb. In order to optimize high-temperature oxidation resistance an understanding of why the Cr(Ta)-Cr2Ta alloys are more oxidation resistant is needed. Detailed EPMA characterization of the oxidized scaleswas initiated as a first steptowards gaining this understanding.Fig. 1 shows a backscattered electron image of cast and heat treated and heat treated Cr-10Nb at.% after a 6 cycle, 120 h exposure at 1100°C in humid air. Most of the coupon was converted to a complex mixture of Cr-, Nb-, and Cr+ Nb- oxides.

OXIDATION RESISTANCE OF LOW-TEMPERATURE PACK ALUMINIZING COATINGS ON NI-BASE SUPERALLOY

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3185-3189 ◽  
Author(s):  
BIFEI YUAN ◽  
LONGWEN YU ◽  
GUIWU LU
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Aluminide Coating ◽  
Nickel Base Superalloy ◽  
Temperature Oxidation ◽  
Pack Aluminizing ◽  
Nickel Base ◽  
Base Superalloy

A nickel-base superalloy has been used to deposit the aluminide coating by low-temperature pack cementation process. The high temperature oxidation tests on aluminized alloys and the uncoated specimens are carried out at 1000°C for 10h. It is observed that a dense and protective Al 2 O 3 surface layer is produced on the aluminized alloy, and the aluminizing process has greatly enhanced the high temperature oxidation resistance of the Ni -base superalloy at 1000°C. As a contrast, the uncoated specimen begins to be failure when treated only for 6h at the same temperature.

AK STEEL 441

Alloy Digest ◽  
2006 ◽  
Vol 55 (6) ◽  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Tensile Properties ◽  
Oxidation Resistance ◽  
Ferritic Stainless Steel ◽  
High Temperature Oxidation ◽  
High Temperature Strength ◽  
Temperature Oxidation ◽  
Temperature Performance

Abstract AK Steel 441 has good high-temperature strength, an equiaxed microstructure, and good high-temperature oxidation resistance. The alloy is a niobium-bearing ferritic stainless steel. This datasheet provides information on composition, hardness, and tensile properties as well as deformation. It also includes information on high temperature performance and corrosion resistance as well as forming and joining. Filing Code: SS-965. Producer or source: AK Steel.

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