ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    Oxidation characteristics of Ti-25Al-10Nb-3V-1Mo (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Static oxidation kinetics of the super-alpha 2 titanium-aluminide alloy Ti-25Al-10Nb-3V-1Mo (at. percent) were investigated in air over the temperature range of 650 to 1000 C using thermogravimetric analysis. The oxidation kinetics were complex at all exposure temperatures and displayed up to three distinct oxidation rates. Breakaway oxidation occurred after long exposure times at high temperatures. Oxidation products were determined using X-ray diffraction techniques, electron microprobe analysis, and energy dispersive X-ray analysis. Oxide scale morphology was examined by scanning electron microscopy of the surfaces and cross sections of oxidized specimens. The oxides during the parabolic stages were compact and multilayered, consisting primarily of TiO2 doped with Nb, a top layer of Al2O3, and a thin bottom layer of TiN. The transition between the second and third parabolic stage was found to be linked to the formation of a TiAl layer at the oxide-metal interface. Porosity was formed during the third stage, causing degradation of the oxide and the beginning of breakaway oxidation.
    Keywords: METALLIC MATERIALS
    Type: Oxidation of Metals (ISSN 0030-770X); 37; 3-4,; 111-124
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Thin coatings for protecting titanium aluminides in high-temperature oxidizing environments (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Titanium aluminides have high specific strengths at high temperatures but are susceptible to environmental attack. Their use in many aerospace applications would require that they be protected with coatings that, for structural efficiency, must be thin. It is conceivable that acceptable coatings might be found in several oxide systems, and consequently, oxide coatings of many compositions were prepared from sol-gels for study. Response-surface methodology was used to refine coating compositions and factorial experiments were used to develop coating strategies. Oxygen permeability diagrams of two-layer coatings for several oxide systems, an analysis of multiple-layer coatings on rough and polished surfaces, and modeling of the oxidation weight gain are presented.
    Keywords: METALLIC MATERIALS
    Type: In: Environmental effects on advanced materials (A93-13601 02-23); p. 107-121.
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Oxidation characteristics of Ti-33Al-6Nb-1.4Ta (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Static oxidation kinetics of the gamma titanium-aluminide alloy Ti-33Al-6Nb-1.4Ta (wt pct) have been investigated in air from 700 to 1000 C and in oxygen from 800 to 1000 C using thermogravimetric analysis. The oxidation kinetics were controlled by the presence of alumina for all oxygen exposures and in air below 800 C, while the kinetics in air above 800 C were more complex. Oxidation products were identified using X-ray diffraction techniques. Oxide scale morphology was examined by SEM and TEM of the surfaces and across sections of oxidized specimens. The oxidation products formed depended on the exposure: Al2O3 and TiO2 were identified on all specimens exposed in and air and oxygen; the nitride phases TiN and Ti2AlN were also found on specimens exposed in air.
    Keywords: METALLIC MATERIALS
    Type: In: Environmental effects on advanced materials (A93-13601 02-23); p. 79-89.
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Titanium aluminides - Surface composition effects as a function of temperature (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Results are presented from an AES investigation of the surface characteristics of pure Ti, Ti-14Al-21Nb (alpha-2 aluminide), and Ti-33Al-6Nb-1.4Ta (gamma aluminide) under ultrahigh vacuum conditions over the 20-1000 C temperature range. The observed variations in surface composition are noted to be dramatic and indicative of a direct relationship between the amount of retained oxygen and carbon on the surface and the quantity of Al in that surface's vicinity. While TiO2 was the main surface oxide for pure Ti and the alpha-2 and gamma aluminides, only metallic peaks were observable at 600 C; at 1000 C, metallic Al and Ti were observed.
    Keywords: METALLIC MATERIALS
    Type: Scripta Metallurgica et Materialia (ISSN 0956-716X); 25; 171-176
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    The surface variation of Ti-14Al-21Nb as a function of temperature under ultrahigh vacuum conditions (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The effect of temperature, at conditions of ultrahigh vacuum, on the surface composition of the Ti-14Al-21Nb (in wt pct) alloy was investigated in samples heated to 1000 C in 100 C increments. Results of AES spectroscopy revealed that the Ti-14Al-21Nb alloy surface is extremely sensitive to temperature. At 300 C, the carbon and oxygen began to rapidly dissolve into the alloy, and at 600 C, bulk S segregated to the surface. The variation in the surface composition was extensive and different over the temperature range studied, indicating that there may be substantial changes in the hydrogen transport.
    Keywords: METALLIC MATERIALS
    Type: Electrochemical Society, Journal (ISSN 0013-4651); 137; 1194-119
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Oxidation of commercial purity titanium (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The oxidation kinetics of commercial purity Ti-A55 exposed to laboratory air in the 593-760 C temperature range were continuously monitored by thermogravimetric analysis. The oxide thickness was measured by microscopy, and the substrate contamination was estimated from microhardness measurements. The microhardness depth profiles were converted to oxygen composition profiles using calibration depth. The oxygen diffusion coefficient in alpha-Ti appears to be approximately concentration-independent in the 1-10 at. pct oxygen range. Diffusion coefficient for oxygen in TiO2 has been estimated as a function of temperature and is found to be about 50 times the value in alpha-Ti. The metallographically prepared cross sections of the oxidized specimens revealed a 'moving boundary' in the substrate, parallel to the oxide-metal interface. This boundary was associated with a specific oxygen level of 5.0 + or - 0.5 at. pct. It occurred at a distance from the oxide-metal interface which was correlatable with temperature and time of exposure. The diffusion coefficient corresponding to the composition of this moving boundary is in excellent agreement with the effective diffusion coefficient for the substrate contamination.
    Keywords: METALLIC MATERIALS
    Type: Oxidation of Metals (ISSN 0030-770X); 26; 231-252
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Use of aluminum as an oxidation barrier for titanium (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A study is conducted of the use of aluminum coatings as oxidation retardants for Ti alloys, using room temperature normal emittance and spectral emittance as bases for the characterization of oxidation properties with and without the coatings. Thermal exposures were conducted in a thermogravimetric analysis apparatus in which specimen weight was continuously monitored. The results obtained indicate that the weight gains are proportional to the square root of the time for uncoated alloys and for 649 C-exposed aluminum-coated alloys. For the 704 C-exposed aluminum-coated alloys, weight gain exhibits a low rate for short and a high rate for long exposure times, implying that the 0.5-micron coating's protection decreases for long exposures at this temperature.
    Keywords: METALLIC MATERIALS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Residual mechanical properties of Ti-6Al-2Sn-4Zr-2Mo after simulated Space Shuttle reentry (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Oxidation and embrittlement are concerns in use of titanium foils for shielding advanced space transportation system vehicles during earth reentry. Ti-6Al-4V in 0.003 in. and 0.035 in. thicknesses were exposed to multiple cycles of simulated space transportation system ascent/reentry conditions at temperatures ranging from 1000 F to 1200 F. Residual mechanical tests and metallurgical analyses were made on the specimens after exposure. Results show that tensile elongation is the mechanical property most affected by the reentry environment. Results are presented to show a comparison of residual properties of foil specimens from static oxidation exposure and cyclic oxidation exposure.
    Keywords: METALLIC MATERIALS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Response of Inconel 617 to sea salt and re-entry conditions (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: METALLIC MATERIALS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 23; 96-101
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Effect of oxygen barrier coatings on oxidation and embrittlement of Ti-6Al-2Sn-4Zr-2Mo foil in heat shield applications (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Because of the loss of ductility with exposure to oxidizing conditions, long time applications of titanium alloys have been limited to temperatures below 700 K and short time applications have been limited to temperatures below 815 K. Oxygen barrier coatings for shielding Ti-6Al-2Sn-4Zr-2Mo alloy from oxidation during exposure to high temperatures were studied using foil gage specimens. The coatings included micrometer-thick sputtered SiO2 and chemical-vapor-deposited silicate layers both with and without an aluminum basecoat. The oxidation rates and resistance to embrittlement of the coated specimens were significantly better than those of the uncoated specimens.
    Keywords: METALLIC MATERIALS
    Type: AIAA PAPER 86-0889
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...