| The Effects of Oxidation-Induced Failures on Thermal Barrier Coatings with Platinum Aluminide and NiCoCrAlY Bond Coats |
01 DEC 2001 |
59 pages |
| Authors:
N. M. Yanar; G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
 | This program has been directed at determining the mechanisms by which oxidation causes failure of thermal barrier coatings (TBCs) and developing modified systems with improved resistance to Oxidation-induced failures. The thermal barrier coating was yttria stabilized zirconia (YSZ) deposited via electron beam vapor deposition (EBPVD). This TBC was deposited on both platinum aluminide and NiCoCrA1Y bond coats which in turn were deposited on superalloy substrates of Rare N5. The oxidation ... |
|
| Cross-Disciplinary Materials Research Program |
31 JUL 97 |
210 pages |
| Authors:
F. S. Pettit; J. T. Yates Jr; PITTSBURGH UNIV PA
|
| This Final Report describes the research progress in the Cross- Disciplinary Materials Program at the University of Pittsburgh during the period February 1, 1995 through April 30, 1997. Research has been Undertaken in three technical areas; High Performance Materials, Optoelectronics, and Catalysis. The projects in High Performance Materials include studies on the oxidation of superalloys, coatings, and other intermetallics, the thermoprocessing of near gamma-TiAl, the wear of diamond films and ... |
|
| Anomalous Oxidation of Intermetallics |
1995 |
|
| Authors:
D. A. Berztiss; F. S. Pettit; G. H. Meier; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
 | This paper concerned metals in some important way and contained information about, utilized, or discussed these subjects: basic topics: experimental materials and material types: al2o3, mosi2, nial, sio2, ti-48al, ti-48al-12cr, ti-48al-4cr, tial, ticral materials related terms: aluminum addition, chromium addition, intermetallic containing alloys, isothermal oxidation, mass spectrometry, oxidation, oxygen addition, sem, silicon addition, single crystal, x-ray diffraction, x-ray spectroscopy parameter values relevant to the data: temp 1200 c and above, ... |
|
| Materials Research Center, University of Pittsburgh |
29 APR 94 |
364 pages |
| Authors:
D. M. Hercules; F. S. Pettit; G. Mayer; PITTSBURGH UNIV PA
|
| The research and related activities at the Materials Research Center (MRC) of the University of Pittsburgh under AFOSR Grant 91-0441 are summarized. The research program has progressed in four technical areas. Nine projects under the heading of High-Performance Materials are discussed and include degradation of intermetallics and composites at elevated temperatures, deformation behavior of alloys during processing and service, and development of polymers with improved mechanical properties through microstructure control. ... |
|
| Platinum-Modified Diffusion Aluminide Coatings on Nickel-Base Superalloys |
MAR 93 |
32 pages |
| Authors:
G. M. Kim; G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Conventional and platinum modified diffusion aluminide coatings on some state-of-theart single crystal and polycrystalline nickel-base superalloys have been compared in tests designed to establish conditions representative of those existing in gas turbines operating over a range of applications. Resistance of these coatings to oxidation, high temperature hot corrosion, and low temperature hot corrosion have been compared. Platinum has been found to significantly improve the resistance of diffusion aluminides to all ... |
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| Spalling Types and Mechanisms in the Erosion-Corrosion of Metals at High Temperature |
1993 |
|
| Authors:
D. M. Rishel; F. S. Pettit; N. Birks; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| An overview of isothermal erosion-corrosion in typical metals is presented. |
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| The Oxidation and Embrittlement of Alpha2 (Ti3Al) Titanium Aluminides |
1993 |
|
| Authors:
J. Rakowski; D. Monceau; F. S. Pettit; G. H. Meier; R. A. Perkins; PITTSBURGH UNIV PA
|
|
| Hot Corrosion of Alumina |
93 |
|
| Authors:
M. G. Lawson; F. S. Pettit; J. R. Blachere; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The hot corrosion of single crystal and polycrystalline aluminas has been investigated in SO2-SO3-O2 environments and in the presence of molten Na2SO4-based deposits at temperatures of 700 and 1000 C. The effect of microstructure and impurities on the corrosion has been emphasized. Weight changes and wetting angles were determined, and the evolution of the morphology of the exposed substrates and the reaction products was investigated in detail. The corrosion was ... |
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| High Temperature Oxidation and Corrosion of Intermetallic Compounds |
92 |
|
| Authors:
G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| A description of the selective oxidation of intermetallic compounds is presented. The development of protective external scales and the process of 'pesting' in relation to temperature are studied. The effects of gas composition on the morphology, oxidation rate, and formation of volatile reaction products are examined. These results are illustrated using selected compounds proposed for high-temperature use. Corrosion behavior of intermetallic compounds in complex environments is studied. |
|
| Oxidation of MoSi2 and Comparison With Other Silicide Materials |
92 |
|
| Authors:
D. A. Berztiss; R. R. Cerchiara; E. A. Gulbransen; F. S. Pettit; G. H. Meier; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The oxidation behavior of MoSi2 in three fabrication conditions has been studied in oxygen and in air. The cast material was studied at 500-1400 C, the hot isostatically pressed (HIP) material at 500 and 1000 C, and single crystals at 500 C. The cast material showed three regimes of behavior. Above 1000 C a continuous protective silica scale formed. Between 600 and 1000 C a silica scale formed, but formation ... |
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| The Oxidation Behavior of Intermetallic Compounds |
92 |
|
| Authors:
G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The selective oxidation of intermetallic compounds is described; it is shown that the fundamental concepts developed for the oxidation of conventional alloys (e.g., iron- and nickel-base alloys) pertain also to the oxidation of intermetallics with slight modifications; the effects of temperature on the development of protective external scales and on the occurrence of "pesting" are considered; the effects of third element additions on the oxidation mechanisms and influence of gas ... |
|
| Oxidation of Low Sulfur Single Crystal Nickel-Base Superalloys |
92 |
|
| Authors:
R. V. McVay; P. Williams; G. H. Meier; F. S. Pettit; J. L. Smialek; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| An investigation on the effects of Hf, Y, and S concentrations on the oxidation resistance of single crystal PWA 1480, PWA 1484, and PWA 1487 Ni alloys was conducted at 1100 C in air. Sulfur was removed from some of the specimens by heating them in dry flowing hydrogen at 1200 C. Results of the oxidation tests show that oxidation resistance was significantly improved by removing sulfur. Hf and Y ... |
|
| Oxidation of MoSi2 and Comparison with Other Silicide Materials |
92 |
|
| Authors:
D. A. Berztiss; R. R. Cerchiara; E. A. Gulbransen; F. S. Pettit; G. H. Meier; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Oxidation behavior of MoSi2 in three fabrication conditions has been studied in oxygen and air. The cast material was studied over a temperature range 500-1400 C, the hot isostatically pressed (HIP) material was studied at 500 and 1000 C and the single crystals were studied at 500 C. The cast material exhibited three regimes of behavior. Above 1000 C a continuous protective silica scale formed. Between 600 and 1000 C ... |
|
| Some Principal Mechanisms in the Simultaneous Erosion and Corrosion Attack of Metals at High Temperatures |
91 |
|
| Authors:
D. M. Rishel; F. S. Pettit; N. Birks; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Combined erosion-corrosion conditions can cause especially severe degradation of materials because the erosive component often adversely affects the protective properties of the corrosion product; this paper describes the various ways that erosive and corrosive processes may interact with one another; depending upon the magnitudes of these components a number of regimes are described for metals and alloys; the pure erosion and pure corrosion regimes prevail when the corrosion component or ... |
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| Oxidation Resistance of Intermetallic Compounds Containing Niobium or Tantalum |
91 |
|
| Authors:
R. R. Cerchiara; G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| Intermetallic compounds of the Nb-Al, NB-Si and Ta-Si systems have been oxidized in oxygen and in air between 800 and 1400C; it was not possible to selectively oxidize aluminum or silicon even in the intermetallics most rich in these two elements; at temperatures in the vicinity of 800C some of the intermetallics degraded via a pest type of oxidation; the oxidation behavior of the intermetallic compounds in these systems is ... |
|
| Oxidation Behavior of Gamma-TiAl |
91 |
|
| Authors:
G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| The oxidation behavior of gamma-TiAl has been studied from 750 to 1100C for aluminum contents which essentially cover the homogeneity range of TiAl (50 to 56 at % Al); exposures were carried out in pure oxygen and various oxygen-nitrogen mixtures; it was discovered that the oxidation behavior depended on temperature, aluminum content, and the composition of the oxidizing gas; protective alumina scales formed in pure oxygen up to a critical ... |
|
| Oxidation Behavior of MoSi2 |
91 |
|
| Authors:
D. A. Berztiss; F. S. Pettit; G. H. Meier; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| The oxidation behavior of MoSi2 in two fabrication conditions (cast and HIPed) has been examined in oxygen and in air from 500 to 1400C; the cast material exhibited three regimes of behavior; above 1000C a continuous protective silica scale formed; Between 600 and 1000C a silica scale formed, but formation of silica down grain boundaries, which are believed to be cracked, was observed; at temperatures near 500C accelerated linear oxidation, ... |
|
| High Temperature Oxidation and Corrosion of Intermetallic Compounds |
91 |
|
| Authors:
G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The oxidation and corrosion behavior of intermetallic compounds at high temperatures has been reviewed. The development of protective oxide scales, pesting, the effect of gas composition on oxidation rates and morphology are discussed. |
|
| Environmental Effects During Application of Materials at Temperatures Above 1200 Degrees C |
91 |
|
| Authors:
N. Birks; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The materials which may have properties for use at temperatures above 1200 C are examined and shown to be some refractory metal alloys, a few intermetallics, a number of ceramics, and composites. It is shown that the most important form of environmentally induced degradation of these materials at temperatures above 1200 C is oxidation. The oxidation of each of these types of material is then examined. It is shown that ... |
|
| Effect of Angle of Incidence on the Combined Erosion-Oxidation Attack of Nickel and Cobalt |
90 |
|
| Authors:
S. L. Chang; F. S. Pettit; N. Birks; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The combined erosion-oxidation of cobalt and nickel at 600 and 780 C over a range of particle-impact angles has been studied by using weight change vs time measurements and extensive morphological and microstructural characterization of exposed specimens; the oxidation process has been found to affect the angular dependence of the degradation rates; the effect is especially significant at low-impact angles where ripples and flakes are developed upon the surfaces of ... |
|
| Some Interactions in the Erosion-Oxidation of Alloys |
90 |
|
| Authors:
S. L. Chang; F. S. Pettit; N. Birks; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The modes of interaction of erosion and high-temperature oxidation, occurring simultaneously on an alloy surface, have been studied using Ni-30Cr, MA754, Ni-20Al, and Co-22Cr-11Al-0.2Y alloys to examine the influence of chromia and alumina scale formation on the erosion of nickel and cobalt base alloys; the results have shown that, in the presence of a rapidly flowing oxidizing gas stream, the evaporation of volatile metal oxides becomes important at lower temperatures ... |
|
| High-Temperature Corrosion of Alumina-Forming Coatings for Superalloys |
01 DEC 89 |
|
| Authors:
G. H. Meier; F. S. Pettit
|
| Diffusion aluminide and CoCrAlY-overlay coatings were examined on PWA 1480, IN-738 and CMSX3 substrates under hot corrosion (1000 C to RT cycled hourly with sodium sulfate applied every 20 h) and dry air isothermal and cyclic oxidation conditions. The isothermal tests were performed at 1100 C and the cyclic tests were run at 1100, 1135 and 1200 C. The influence of platinum addition to the aluminide coatings and yttrium and ... |
|
| Program to Study the Oxidation of Carbon-Carbon Composites and Coatings on These Materials |
30 SEP 89 |
209 pages |
| Authors:
J. Cullinan; J. Schaeffer; E. A. Gulbransen; G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The oxidation of carbon-carbon composites and coatings on these composites in oxygen at temperatures between 300 to 1400 C has been investigated. State-of-the art systems have been characterized prior to the oxidation studies by using optical and scanning electron microscopy. It has been determined that uncoated carbon-carbon composites cannot be used at temperatures above about 400 C for extended periods of time because of oxidation. Oxidation does occur at temperatures ... |
|
| Microscopy of the Corrosion of High-Temperature Coatings |
89 |
|
| Authors:
G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Microscopy is used to study the morphology and hot corrosion properties of diffusion aluminide, zirconia thermal barrier, and CoCrAlY overlay coatings; the results of adding platinum to the diffusion aluminide coating are examined in detail. |
|
| Program to Study the Oxidation of Carbon-Carbon Composites and Coatings on These Materials |
31 AUG 88 |
76 pages |
| Authors:
J. Cullinan; J. Schaeffer; E. A. Gulbransen; G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Carbon carbon composites are being considered for aerospace applications due to their light weight and excellent mechanical properties. Depending upon the application, carbon carbon composites are expected to be used for periods ranging from about 10 hours to a few thousand hours at temperatures above 1000 C and approaching 2200 C. A major problem in using such materials in oxidizing environments is that carbon reacts with oxygen forming gaseous carbon ... |
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| High Temperature Corrosion of Ceramics |
30 DEC 87 |
|
| Authors:
J. R. Blachere; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The materials investigated were silica, alumina, silicon nitride and silicon carbide. In addition to the purer single crystals or CVD materials typical engineering materials of various purities were included in the study except for the silica which was vitreous. The corrosion conditions were 'hot corrosion' in which gaseous corrosion was enhanced by sodium sulfate deposits. Some gaseous corrosion and oxidation experiments were also performed mostly as baseline for comparison with ... |
|
| Study of the Erosion Corrosion of Alloys and Coatings |
DEC 87 |
|
| Authors:
N. Birks; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Apparatus has been developed that allows the erodent size, speed and impact angle on the target to be varied independently. The apparatus also allows temperature and atmosphere composition to be selected. Reliable and reproducible kinetic data have been obtained for the exposure of samples of a range of metals and alloys in the apparatus. When erosion and oxidation processes interact in the degradation of a specimen, an acceleration in the ... |
|
| Transmission Electron Microscopy Characterization of the Microstructure of a CoCrAlY Electron Beam Physical Vapor Deposition Coating on IN738 |
NOV 86 |
|
| Authors:
J. R. Caola; G. H. Meier; F. S. Pettit
|
| The microstructures of commercially prepared electron beam physical vapor deposition CoCrAlY coatings on drop cast IN738LC substrates were studied using a technique developed for preparing cross-sectional transmission electron microscope (TEM) specimens of exceptional mechanical stability. The microstructure was found to vary as a function of processing condition, starting as a fine dispersion of the alpha, beta, and epsilon phases, after coating, distinguishable only with the aid of a TEM. This ... |
|
| Advanced High Temperature Coating Systems Beyond Current State of the Art Systems |
15 APR 86 |
|
| Authors:
A. Ashary; G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Alpha-Al2O3 and the SiO2 are the two most effective reaction product barriers that can be used to protect alloys from oxidation at temperatures above 1000 C. In the present work the techniques to improve the adherence of Al2O3 scales on MCrA1 coating alloys are studied and the characteristics of SiO2 scales formed on Ni-Si alloys are investigated. The theoretical aspects of oxide-metal adhesion are examined and the factors which affect ... |
|
| High Temperature Corrosion of Ceramics, |
MAR 1985 |
|
| Authors:
J. R. Blachere; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| This report focusses on the high temperature corrosion of silicon nitride, SiC, alumina and silica in presence of sodium sulfate deposits. High purity materials as well as selected engineering material are under study. Detailed results are presented for the hot corrosion of silicon carbide and silicon nitride under basic conditions. Features of the hot corrosion of silica and alumina under both acid and basic corrosion and some new experiments are ... |
|
| Research Directed Advanced High Temperature Coating System Beyond Current State-of-the Art Systems |
DEC 84 |
|
| Authors:
A. Ashary; G. H meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| Alloy systems have been investigated to determine the reaction product barriers that can be used to provide optimum resistance to high temperature oxidation. The reaction product barriers which can be used are Al(2) O(3), Cr(2)O(3), and SiO(2) with the use Cr(2)O(3), being restricted to below about 1000 C due to formation of volatile products. The oxidation of nickel- silicon alloys has been studied over the internal 900-1100 C. Compositions of ... |
|
| Oxidation and Hot Corrosion of Superalloys |
OCT 84 |
|
| Authors:
F. S. Pettit; G. H. Meier; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| The oxidation, mixed gas corrosion and hot corrosion of nickel-, cobalt- and iron-base superalloys at temperatures above about 600 C are examined. The times for which such oxide reaction product barriers are stable upon the surfaces of superalloys is discussed by first considering how these oxide scales are formed and then how they are destroyed in use. For oxidation environments that these oxide scales are degraded primarily via cracking and ... |
|
| High-Temperature Corrosion of Ceramics |
JUN 84 |
|
| Authors:
J. R. Blachere; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| The program has given significant results which are beginning to appear in a number of presentations and publications. The materials under study have been alumina, silicon nitride and silicon carbide with various microstructures and impurity levels. They range from high purity single crystals and CVD materials to relatively improve engineering materials. A high purity silicon dioxide glass was studied also. The investigation emphasizes the fundamental understanding of the high temperature ... |
|
| Interactions between Erosion and Corrosion of Metals and Alloys at Elevated Temperatures |
APR 1984 |
|
| Authors:
N. Birks; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| Structural alloys and coating alloys have been developed that successfully resist high temperature oxidation and, to a lesser extent, hot corrosion-depending on conditions. Such protection depends upon the maintenance of a surface layer of oxide that effectively separates the metal from the reactive environment. The oxide protective coatings may however be damaged by erosion by solid particles in the gas flow, the effect being worse when the velocity of the ... |
|
| High Temperature Corrosion of Ceramics, |
FEB 1984 |
|
| Authors:
J. R. Blachere; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| This report focuses on the hot corrosion of silicon nitride and silicon carbide at 1000 C in sulfur dioxide-sulfur trioxide-oxygen and oxygen atmospheres. The materials under study are, high purity and impure engineering materials, silicon nitride and silicon carbide. The oxidation was studied as a preoxidation treatment at 1400 C for the corrosion studies and in general the results are in good agreement with published data, in particular for the ... |
|
| Field Test of Two High Pressure, Direct Contact Downhole Steam Generators, Volume III: Metallurgical Analyses |
OCT 83 |
|
| Authors:
J. F. Muir; L. J. Weirick; F. S. Pettit; SANDIA NATIONAL LABS ALBUQUERQUE NM
|
| Two prototype downhole steam generator systems were operated in an oil field environment during a test in Long Beach, CA, from June 1981 through March 1982. One generator burned diesel fuel in air and was located downhole, the other burned diesel in oxygen and was operated on the surface. Components of the two systems experienced varying degrees of corrosion during the test. Materials examined included plain carbon steel (API Grade ... |
|
| Fundamental Research Directed to Advanced High Temperature Coating Systems Beyond the Current State-of-the-Art Systems |
07 JUN 1983 |
|
| Authors:
G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| The oxidation in air of nickel-silicon alloys with compositions extending from 5 to 20 weight-silicon have been studied over the temperature interval between 900 and 1100 degs C. In the case of alloys with less than 20% silicon, the silicon is not oxidized internally nevertheless the rates of oxidation are greater than those for alloys upon which alumina scales are formed. The alloy with 20% silicon exhibited oxidation rates less ... |
|
| ACOUSTIC EMISSION STUDY OF OXIDE CRACKING DURING ALLOY OXIDATION |
MAR 83 |
|
| Authors:
A. Ashary; G. H. Meier; F. S. Pettit
|
| a major factor in the life of oxidation resistant alloys and coatings is the extent to which they accomodate stresses generated both during isothermal oxidation and thermal cycling. the cracking and spalling of oxides on both cr(sub 2)o(sub 3)-forming alloys (ni-30cr, ni-50cr) and al(sub 2)o(sub 3)- forming alloys (ni-20cr-10ai, co-20cr-10al) have been studied during isothermal and cyclic exposure using an acoustic emission technique. these results have been correlated with standard ... |
|
| High-Temperature Corrosion of Ceramics |
FEB 83 |
|
| Authors:
J. R. Blachere; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| In this program, the corrosion of ceramics is studied from a mechanistic point of view. In an integrated fundamental approach the gaseous corrosion investigation is followed by that of deposit-modified gaseous corrosion and eventually by deep melt corrosion. The study of the gaseous corrosion of alumina and silicon dioxide at temperatures of 700, 1000 and 1400 C in atmospheres of water-hydrogen, carbon dioxide and sulfur dioxide-SO(sub 3) is almost completed. ... |
|
| Fundamental Research Directed to Advanced High Temperature Coating Systems Beyond the Current State-of-the-Art Systems |
01 APR 1982 |
|
| Authors:
G. H. Meier; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| The oxidation behavoir of Ni-7.5 Si alloys has been studied in oxygen over the temperature range from 950 to 1150 deg C. The alloys exhibit significant transient oxidation but following this period oxidize at rates which are similar to those for A1203-forming systems. This slow rate is apparently due to the formation of sealing layer of Si02 at the alloy/scale interface. The sealing layer appears to be slightly permeable to ... |
|
| High-Temperature Corrosion of Ceramics |
FEB 82 |
|
| Authors:
J. R. Blachere; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| A program of research on the high-temperature corrosion of ceramics is in its first year. The program of research is fundamental in nature and emphasizes an integrated approach which considers gaseous, deposit-modified gas- induced and eventually deep-melt corrosion. However, the focus is on deposit- modified corrosion. The materials under study are silica in bulk and as a scale on Si(sub 3)N(sub 4) and SiC; Al(sub 2)O(sub 3), Cr(sub 2)0(sub 3) ... |
|
| High-Temperature Corrosion of Ceramics. |
1982 |
|
| Authors:
J. R. Blanchere; F. S. Pettit; PITTSBURGH UNIV PA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| A program of research on the high-temperature corrosion of ceramics in its first year, is described. The program of research is fundamental in nature and emphasizes an integrated approach which considers gaseous, deposit-modified gas-induced and eventually deep-melt corrosion. However, the focus is on deposit-modified corrosion. The materials under study are silica in bulk and as a scale on silicon nitride, silicon carbide, alumina, chromium oxide and alumina-chromium oxide solid solutions ... |
|
| Corrosion of Metals and Alloys in Mixed Gas Environments at Elevated Temperatures |
OCT 80 |
|
| Authors:
C. S. Giggins; F. S. Pettit
|
| The attack of nickel, cobalt, iron, and alloys of these metals containing chromium and aluminum, by gases containing sulfur-oxygen, carbon- oxygen, and nitrogen-oxygen has been studied at temperatures of 600 and 900 C. The degradation of these metals and alloys was characterized by using standard analytical techniques with emphasis on optical metallography. Three types of accelerated degradation were identified for the attack of alloys by gases containing another oxidant in ... |
|
| Materials Problems in Fluidized-Bed Combustion Systems--High-Temperature Erosion-Corrosion by High-Velocity (200m/s) Particles |
MAY 80 |
|
| Authors:
R. H. Barkalow; J. A. Goebel; F. S. Pettit; PRATT AND WHITNEY AIRCRAFT MIDDLETOWN CONN
|
| The response of (IN-738, MA-754, X-40, HA-188), aluminide coatings for these alloys, and silicon nitride to erosion-oxidation and erosion-hot corrosion conditions has been studied at 871 C in a high velocity gas stream 200 m/sec. The experiments were performed in a dynamic combustor (burner rig) operated on aircraft - grade jet fuel and compressed air. Erosive conditions were achieved by injecting abrasive powder into the burner rig. Alumina powders with ... |
|
| Erosion/Hot Corrosion Laboratory Evaluation of Metallic Alloys and Coatings |
DEC 79 |
|
| Authors:
R. H. Barkalow; F. S. Pettit; PRATT AND WHITNEY AIRCRAFT GROUP EAST HARTFORD CONN COMMERCIAL PRODUCTS DIV
|
| Of the possible degradation mechanisms due to particle-laden gas streams in alternate fuel capable turbine engines, the two most serious appear to be erosion-hot corrosion interactions and mechanical or chemical effects of ash fouling. The solution to these problems will undoubtedly involve both materials and design considerations. Materials must be as resistant as possible, then the gas clean-up system must be as good as necessary, at the expense of capital ... |
|
| Mechanisms of Hot Corrosion Attack of Ceramic Coating Materials |
DEC 79 |
|
| Authors:
R. H. Barkalow; F. S. Pettit; PRATT AND WHITNEY AIRCRAFT GROUP EAST HARTFORD CONN COMMERCIAL PRODUCTS DIV
|
| As in the case of metallic systems, ceramics can undergo hot corrosion attack via either acidic or basic reactions. Yttria stabilized zirconia, for example, is susceptible to selective removal of yttria by an acidic reaction, while silica-containing or silica-forming ceramics exposed to the same environmental conditions can degrade by a basic reaction. An important difference from the behavior of metals, however, is that hot corrosion of oxide ceramics appears to ... |
|
| Marine Gas Turbine Hot Corrosion Dependence on Ingested Salt Levels. |
16 APR 1979 |
|
| Authors:
R. H. Barkalow; F. S. Pettit; PRATT AND WHITNEY AIRCRAFT GROUP WEST PALM BEACH FL GOVERNMENT PRODUCTS DIV
|
| Turbine section hardware in marine engines is susceptible to hot corrosion attack induced by salt deposition. In attempting to control this type of materials degradation, it is necessary to examine the dependence of hot corrosion on ingested salt level and to determine the deposition rate below which hot corrosion attack will be negligible. Test specimens (uncoated and aluminized Mar-M509 and IN792, CoCrAlY-coated IN 792) were exposed at 700 and 900 ... |
|
| Degradation of Coating Alloys in Simulated Marine Environments. |
15 JUN 1978 |
|
| Authors:
R. H. Barkalow; F. S. Pettit; PRATT AND WHITNEY AIRCRAFT GROUP EAST HARTFORD CT MATERIALS ENGINEERING AND RESEARCH LAB
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| Chloride- and SO3 induced hot corrosion of state-of-the-art and developmental coatings were studied in a program of laboratory hot corrosion testing correlated with metallographic examination of service hardware. Laboratory furnace tests showed that CoCrAlY coatings are highly susceptible to degradation by chloride-containing salt deposits; the mechanism of attack involves dealloying of aluminum via formation of an interconnected network of coarse and fine pores. Sputtered platinum overlayers are an effective means ... |
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| The Effects Produced by Platinum in High Temperature Metallic Coatings |
78 |
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| Authors:
J. A. Goebel; R. H. Barkalow; F. S. Pettit; PRATT AND WHITNEY AIRCRAFT MIDDLETOWN CONN
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| Techniques by which platinum can be added to diffusion aluminide and MCrAlY overlay coatings are discussed. It is shown that platinum improves the oxidation resistance of aluminide coatings by inhibiting the cracking and spalling of the alpha-Al(sub 2)O(sub 3) scales. Platinum can affect the resistance of coatings to certain types of hot corrosion attack. Platinum overlayers on CoCrAlY were found to be very effective in inhibiting the hot corrosion attack ... |
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| THE ADHESION OF AL(SUB 2)O(SUB 3) SCALES ON ALLOYS |
SEP 75 |
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| Authors:
C. S. Giggins; E. J. Felten; F. S. Pettit; PRATT AND WHITNEY AIRCRAFT MIDDLETOWN CONN
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