Oxide scales growth

Directed Oxidation of a Molten Metal. Directed oxidation of a molten metal or the Lanxide process (45,68,91) involves the reaction of a molten metal with a gaseous oxidant, eg, A1 with O2 in air, to form a porous three-dimensional oxide that grows outward from the metal/ceramic surface. The process proceeds via capillary action as the molten metal wicks into open pore channels in the oxide scale growth. Reinforced ceramic matrix composites can be formed by positioning inert filler materials, eg, fibers, whiskers, and/or particulates, in the path of the oxide scale growth. The resultant composite is comprised of both interconnected metal and ceramic. Typically 5—30 vol % metal remains after processing. The composite product maintains many of the desirable properties of a ceramic however, the presence of the metal serves to increase the fracture toughness of the composite. 

RE reducing oxide scale growth stresses (preventing scale cracking)... 

Specific Aspects of Oxide Scale Growth on Alloys. 86... 

The types of high temperature corrosion mentioned so far will be discussed in more detail in later sections. Before doing so, however, fire next section will deal with the aspect of high temperature corrosion protection and the fundamentals of oxide scale growth. The reason for this is that the key... 

It has repeatedly been confirmed that in chromia-forming alloys, the mechanism of oxide-scale growth is changed in the presence of rare-earth elements from cation to anion control, and consequently the direction of growth also changes (Hussey et al. 1989, Graham 1991). 

With a native oxide scale growth on the stmctural material, in general no degradation due to liquid metal can be observed, unless inhomogeneity, flaws, and cracks in the oxide allow contact between the steel and the liquid metal. 

K. Hack, S. Petersen, P. Koukkari and K. Penttila. CHEMSHEET - an Efficient Worksheet Tool for Thermodynamic Process Simulation. In Y. Brechet (editor), EUROMAT 99 Volume 3, Wiley-VCH Pubhshers, Weinheim, 2000, pp. 323-330. 14. U. Krupp, V. B. Trindade, P. Schmidt, H.-J. Christ, U. Buschmann and W. Wiechert. Computer-based Simulation of inward oxide scale growth on Cr-containing steels of high temperatures (OPTICORR), Chapter 32 this volume. 

Computer-based simulation of inward oxide scale growth on Cr-containing steels at high temperatures (OPTICORR)... 

Mn increases the oxide scale growth rate even if a lanthanide element is present, and preferentially forms a Cr-Mn spinel with low electrical resistance on top of a chromia scale... 

Schematic showing the effect of oxide scale growth by counterdiffusion leading to compressive intrinsic oxide growth stresses (a). If diffusion in one direction is suppressed by doping (e.g., REE) the scale grows only on one side and no intrinsic growth stresses are built up (b). (From Kofstad, P., High Temperature Corrosion, Elsevier Applied Science, London, U.K., 1988.)...

Application to the role of the oxide/metal interface during oxide scale growth... 

Pieraggi B, Rapp R A and Hirth J P (1995), Role of interface structure and interfacial defects in oxide scale growth , Oxid Met, 44(1/2), 63-79. 

R. Y. Chen, W. Y. D. Yuen and T. Mak, Oxide scale growth and its pickling characteristics of hot-roUed steel strip , 43rd MWSP Conf. Proc., ISS, 39, 287-299 (2001). 

The main consequence of the RE segregation at the oxide grain boundaries is the change in the oxide scale growth mechanism. Table 10.6 shows that the transport of oxygen becomes predominant in RE doped alumina layers [26,27,37,38,40-48,174,176-180]. 

Liu Z, Gao W, Dahm K L, Wang F, The effect of coating grain size on the selective oxidation hehaviour of Ni-Cr-Al alloy , Scripta Mater, 37 (1997) 1551-1558 Strauss D, Muller G, Schumacher G, Engelko V, Stamm W, Clemens D, Quadakkers W J, Oxide scale growth on MCrAlY bond coatings after pulsed electron beam treatment and deposition of EBPVD-TBC , Surf Coat Technol, 2001, 135(2—3), 196-201... 

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