Good High Temperature Oxidation Research Articles

DELORO STELLITE 20

Abstract Deloro Stellite 20 is a Co-Cr-W-C alloy. It is the most abrasion resistant standard cobalt based alloy. Its high chromium content ensures good general corrosion resistance and high-temperature oxidation resistance, while the increased tungsten level provides superior high-temperature properties as compared to Stellite 6 or 12. While it has low shock resistance, it is often the only answer for some applications such as slurry pumps or chemical resistant parts. It is typically used up to a temperature of about 600 °C (1110 °F), depending on the application. This datasheet provides information on composition, physical properties, microstructure, hardness, and tensile properties. It also includes information on corrosion resistance. Filing Code: Co-135. Producer or source: Deloro Wear Solutions GmbH.

Permodur 4742

Abstract Permodur 4742 is an alloy with good high temperature strength and oxidation resistance and has an aluminum addition. The alloy is also called Ferrotherm 4742 at Edelstahlwerke Südwestfalen GmbH. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on forming, heat treating, machining, and joining. Filing Code: SS-1284. Producer or source: Deutsche Edelstahlwerke.

The influence of thermal exposure on the microstructure of a Ni3Al-based single crystal superalloy

The effect of thermal exposure on the microstructure of an Ni3Al-based single crystal superalloy was investigated. The Ni3Al-based single crystal superalloy used in this experiment contained a high content of molybdenum (Mo) and a low content of chromium (Cr), which had good high-temperature strength and oxidation resistance. The alloy was exposed at 1020–1200°C for different time periods. The microstructure after thermal exposure was examined by scanning electron microscope (SEM) and field emission microscope (FEM). The results indicated that precipitation of needle-like topologically close-packed (TCP) phases was only observed at certain intermediate temperature intervals (1020–1080°C). Moreover, once the TCP phases precipitated, they would not dissolve back even after thermal exposed for 1000 h. No precipitation phases were observed after high-temperature thermal exposure at 1100–1200°C for 25 h.

Synthesis and Characterization of Fluorinated Alkyl Substituted Disiloxane

Alkyl substituted disiloxanes demonstrated promising applications as high performance hydraulic oil, diffusion pump oil, etc. In this study, fluorinated alkyl substituted disiloxane was synthesized via Grignard reaction followed by condensation reaction. Its chemical structure was verified by FTIR and NMR. Measurement results showed that this silicon oil exhibited good high temperature performance, oxidation resistance and rust resistance.

Microstructure and Formation Mechanism of Aluminized Coatings on Nickel-Based Superalloys

Aluminized coatings prepared on nickel-based superalloys can provide good protection against high temperature oxidation and hot corrosion. This study investigated the simple aluminized and silicon-aluminized coatings on nickel-based superalloy K4104. The simple aluminized coating was prepared by pack cementation and the Al-Si coating was prepared by slurry aluminizing, respectively. The microstructure of simple aluminized and Al-Si coatings was analyzed by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA). And the formation mechanism of simple aluminized and Al-Si coatings was discussed. The results showed that the simple aluminized coating was about 49 um thick and consisted of three layers. The outer layer mainly consisted of Al-rich β-NiAl. The intermediate layer consisted of Ni-rich β-NiAl and Cr-rich. The inner diffusion layer consisted of Cr-rich and γ’-Ni3Al. The microstructure of Al-Si coating showed that the coating was about 70 um thick and consisted of five layers. The Al-Si coating consisted of CrxSiy, Al-rich β-NiAl, Ni-rich β-NiAl, Cr-rich and γ’-Ni3Al. The microstructure of simple aluminized coating was compared with that of Al-Si coating in order to find out the effect of Si. Owing to the effect of Si, there was a Transition layer in Al-Si coating. The Al-Si coating was thicker than simple aluminized coating. The declining trend of the aluminum concentration in the Al-Si coating was smoother than that of the simple aluminized coating.

SIRIUS 310

Abstract Sirius 310 is a high-temperature stainless steel with 25% Cr, 0.6% Si, and 20% Ni to provide good high-temperature strength and oxidation resistance. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and shear strength as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming and joining. Filing Code: SS-945. Producer or source: Industeel USA, LLC.

High-temperature oxidation behaviour of laser-clad NiCrAlY

Summary To achieve greater efficiency, modern industrial plants are now required to be operated under more arduous process conditions, such as operation in harsher corrosive environments at elevated temperature.1 Plant construction materials require both good high-temperature mechanical properties and better oxidation resistance. One solution has been to use composite materials and most notably surface treatment techniques. Available surface treatment techniques include PTA (plasma transferred arc welding), CVD (chemical vapour deposition), PVD (physical vapour deposition), laser cladding, etc. Laser cladding has a high energy density enabling high melting point materials or even ceramics to be overlaid on the substrate and also offers good controllability together with the advantage of low dilution from the substrate. The oxidation behaviour of laser-clad NiCrAlY layers, however, has so far been poorly documented in the literature. This paper therefore describes an investigation of the oxidation behaviour of NiCr10AlY and NiCr20AlY clad layers formed in single layers in air using prepressed powder with regard for the effect of dilution from the substrate. The effects of the Al content and heat treatment are also examined. The results obtained may be summarised as follows. 1. The oxide formed on the NiCr1OAlY and NiCr20AlY clad layers is mainly α-Al2O3, and the growth rate of the oxide obeys a parabolic rate law. 2. The parabolic rate constant of the NiCr10AlY clad layer is of the same order as that of the bulk material, and the clad layer formed in a single layer by laser cladding has an oxidation resistance equivalent to that of the bulk material. 3. The parabolic rate constant of the NiCr20AlY clad layer is 1–2 orders of magnitude greater than that of the NiCr10AlY clad layer. This is due to the formation of unstable and faster growing 0-Al2O3 during oxidation. 4. Heat treatment of the clad layers produced by laser cladding is effective for improvement of the oxidation resistance. This is due to the fact that heat treatment makes the aluminium distribution in the clad layer more homogeneous, which enhances the nucleation of Al2O3 in the initial stage of oxidation, resulting in a lower parabolic rate constant.

Magnetic moment studies on nickel coated titanium powders

Titanium aluminide intermetallics are gaining greater importance due to their low density, high melting temperature, good high temperature properties and oxidation resistance. Their brittle behaviour at low temperatures has resulted in several investigations aimed at improving their ductility. This can be improved either by suitably alloying or by microstructure control [1–5] and in some cases by both. In general, microstructural refinements developed through processing lead to improvements in both strength and ductility [6]. Thus, processing techniques that increase the range of attainable microstructures are fundamental to the development of new engineered materials. These alloys cannot be produced by the traditional metallurgical processes, because of the restricted range of the atomic percentage of the alloying elements. Conventional powder metallurgical (P=M) techniques can be used for preparing these alloys, with an additional step involving coating on the elemental powders. There are several coating methods available like vapour phase deposition techniques, spray deposition, electroplating, and electroless coating. Each of these has its advantages and disadvantages. Vapour phase deposition methods can be used for coating towbased fibres such as carbon fibres [7]. Electroplating methods can also be used for carbon fibres, for which the substrate should be a conducting material. Coating a powder with a particular element is easier by the electroless coating method because it gives a uniform coating on the substrate. The electroless plating process is an intermediate step in the fabrication of ceramic–metal and metal– metal composites, because it gives a uniform adherent metal coating on substrates. Electroless nickel can be applied to metallic surfaces as well as non-metallic materials to provide a coating of uniform thickness with excellent chemical and physical properties [8]. The production of the titanium aluminide intermetallic alloy from mixtures of the elemental powders may not produce a chemically homogeneous product under normal P=M processes. With pre-alloyed powders, the problem of heterogeneity can be largely eliminated, but it is not cost-effective. Electroless coatings on metal powders enable the coated powder to exhibit a high level of homogeneity during P=M preparation. The aim of this work was to investigate the feasibility of obtaining a satisfactory electroless nickel coating on Ti elemental powders and to analyse this coating with the help of magnetic properties. Measurement of magnetic moment is a novel idea to confirm the presence of nickel on the titanium elemental powders. The presence of nickel coating on titanium powders was further confirmed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) studies. Elemental powders of commercially pure titanium (,75 im) were used for the coating of nickel. The composition of the chemical deposition bath used for the coating of nickel on titanium powder is given in Table I. The proportion of elemental powders added to the coating bath was 70 g to 1 l. A pH of 8–9 was maintained by adding ammonia solution to the bath. With slow stirring, using a magnetic stirrer, all of the particles were allowed to come into contact with the solution. A temperature of 88 8C was maintained throughout the experiment. The coating time was varied (20, 30 and 40 min.) to increase the amount of nickel coated on the elemental powders. The coated powders were rinsed in distilled water, filtered out and dried under infrared (IR) light. Chemical analysis for the presence of nickel was done using dimethyl glyoxime dissolved in methanol. A purple precipitate confirmed the presence of nickel. The presence of coating was analysed with the help of SEM. The presence of nickel as a coating on the elemental powders was confirmed by EDS analysis. Figs 1 and 2 show the SEM micrographs of the uncoated and coated titanium powders. Fig. 3 shows the EDS analysis of nickel-coated titanium powders. Figs 2 and 3 establish the presence of nickel as a coating on the substrate. The magnetic moment test was conducted on the coated particles to confirm the increase in the coating thickness with time. The coating material and the substrate are ferromagnetic and paramagnetic, respectively. From the theory of magnetism, the magnetic moment increases directly with the increase in susceptibility of the material. This concept is used here to determine the increase in coating thickness. Fig. 4 shows magnetic moment plotted against magnetic field for different coating durations. The magnetic moment slowly increases

Effect of prior cooling rate on the grain size of fully-lamellar TiAl-base alloy developed by tempering/quenching

The near-gamma titanium aluminides are attractive for aerospace and automobile applications, because of their low density, good high-temperature strength and acceptable oxidation resistance. Investment casting appears to be the lowest cost alternative for the manufacture of near-net-shape TiAl components; but, the unavoidable remnant of coarse ingot grains in the final product deteriorates the advance of cast alloy. Recently, the authors found that the fine lamellar structure can be developed in cast TiAl-base alloy by a quenching/tempering process. By recrystallization of the quenched massive {gamma} structure at temperature above the {alpha} transus, a fine fully-lamellar structure with a grain size of 150 {micro}m can be obtained. For the engineering application of this process, it must be considered that, in some TiAl-base alloys, microcracks might be introduced during water quenching, and for thick-wall TiAl components, the cooling-rate in center region is lower than that in the surface. In this context, this paper aims to study the effect of prior cooling rate on the tempered lamellar grain size in a cast Ti48Al2W0.5Si alloy.

HAYNES ALLOY No. 718

Abstract HAYNES alloy No. 718 is a precipitation-hardening nickel-base alloy with good ductility and excellent high-temperature strength and oxidation resistance. It is produced by vacuum melting and consumable electrode remelting, either electroslag or vacuum arc. The alloy welds readily and it excels in resisting post-weld (strain-age) cracking. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, and joining. Filing Code: Ni-359. Producer or source: Haynes International Inc..

WESTINGHOUSE W545

Abstract WESTINGHOUSE W545 is a heat treatable iron-base alloy having good high temperature strength and oxidation resistance. It is corrosion and heat resistant. Temperature range of principal usage is 1100 F. to 1350 F. Made by Consumable Electrode Vacuum Arc Melting Only. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SS-87. Producer or source: Midvale-Heppenstall Company.

DISCALOY

Abstract DISCALOY is an iron-base heat treatable alloy having good high temperature strength and oxidation resistance. It is corrosion and heat resistant. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness, creep, and fatigue. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SS-50. Producer or source: Westinghouse Electric Corporation.