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  • 1
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    Sodium hydroxide anodization of Ti-Al-4V adherends (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The use of sodium hydroxide anodization (SHA) for Ti-6Al-4V adherends is examined. The SHA surface is evaluated using SEM, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. The SHA procedures of Kennedy et al. (1983) were employed in this experiment. The photomicrographs of the SHA (sandblasted) and PSHA (sandblasted and pickled) oxide surface reveal that the two surfaces differ. The PSHA is patchy and similar to a chromic acid anodization surface and the porosity of the PSHA is more uniform than the SHA surface. The compositions of the surfaces are studied. It is noted that SHA is an effective pretreatment for Ti-6Al-4V adherends.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: Journal of Adhesion (ISSN 0021-8464); 20; 283-291
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Adhesive evaluation of water-soluble LARC-TPI (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The water-soluble polyimide, identified as TPI(MTC)/H2O, was evaluated as a high temperature thermoplastic adhesive for bonding Ti-6Al-4V and comparing those results primarily with results reported in earlier work with the polyamic-acid/diglyme material. The lap shear strength test was the primary test performed to evaluate the adhesive before (controls) and after thermal exposure in air at 204 C for up to 5000 hours and after a 72 hour water-boil exposure. Lap shear strengths were determined at RT, 177, 204, and 232 C. The adhesive was also characterized after fracture by determining the glass transition temperature as well as defining the mode of failure by visual observation. In general, the results indicate that the TPI(MTC)/H2O retains high lap shear strengths after thermal exposure but had reduced strengths after the water-boil exposure. All failures were cohesive. The TPI(MTC)/H2O compared very well with previous data reported for the standard polyamic-acid/diglyme LARC-TPI results, and therefore, shows promise as a water-soluble adhesive for use in various applications.
    Keywords: NONMETALLIC MATERIALS
    Type: International Journal of Adhesion and Adhesives (ISSN 0143-7496); 8; 25-32
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    SEM/XPS analysis of fractured adhesively bonded graphite fibre-reinforced polyimide composites (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The surfaces of the graphite fiber-reinforced polyimide composites presently pretreated prior to bonding with polyimide adhesive contained variable amounts of a fluoropolymer, as determined by X-ray photoelectron spectroscopy. Lap shear strengths were determined for unaged samples and for those aged over 500- and 1000-hour periods at 177 and 232 C. Unaged sample lap strengths, which were the highest obtained, exhibited no variation with surface pretreatment, but a significant decrease is noted with increasing aging temperature. These thermally aged samples, however, had increased surface fluorine concentration, while a minimal concentration was found in unaged samples. SEM demonstrated a progressive shift from cohesive to adhesive failure for elevated temperature-aged composites.
    Keywords: COMPOSITE MATERIALS
    Type: Composites (ISSN 0010-4361); 16; 207-219
    Format: text
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  • 4
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    Adhesive evaluation of LARC-TPI and a water-soluble version of LARC-TPI (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The results of a study to evaluate two Langley Research Center thermoplastic polimide (TPI) materials, identified as TPI/MTC for the material from Mitsui Toatsu Chemicals Inc. and TPI/H2O for the material from United Technologies Research Center, as high temperature thermoplastic adhesives and primers for bonding titanium (6AL-4V) adherends are discussed. A limited characterization of the materials was performed using a Diffuse Reflectance-Fourier Transform Infrared Spectroscopy (DR-FTIR) technique. Thermomechanical Analysis (TMA) and torsional braid techniques were used to determine glass transition temperature. The adhesive's strength, as determined by simple lap shear tests, was used to evaluate the effects of long term thermal exposure (up to 1000 hrs) at 204 deg C and a 72-hour water-boil.
    Keywords: NONMETALLIC MATERIALS
    Type: International Journal of Adhesion and Adhesives (ISSN 0143-7496); 6; 12-20
    Format: text
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  • 5
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    Evaluation of a novel thermoplastic polyimide for bonding titanium (1986)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A novel hot-melt processable polyimide has been synthesized and characterized as an adhesive for a titanium alloy. This system shows potential for applications with service temperatures near 200 C. A bonding cycle was developed from preliminary processing studies. The bonded specimens were tested at room temperature, 177 C and 204 C both before and after aging in air at 204 C for times up to 1000 hours. There was no appreciable change in strength after aging. Bonded specimens were exposed to boiling water continuously for a 72 hour period. These specimens exhibited some loss in strength due to this rather severe exposure.
    Keywords: NONMETALLIC MATERIALS
    Type: International Journal of Adhesion and Adhesives (ISSN 0143-7496); 6; 25-30
    Format: text
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  • 6
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    Processing study of a high temperature adhesive (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An adhesive-bonding process cycle study was performed for a polyimidesulphone. The high molecular weight, linear aromatic system possesses properties which make it attractive as a processable, low-cost material for elevated temperature applications. The results of a study to better understand the parameters that affect the adhesive properties of the polymer for titanium alloy adherends are presented. These include the tape preparation, the use of a primer and press and simulated autoclave processing conditions. The polymer was characterized using Fourier transform infrared spectroscopy, glass transition temperature determination, flow measurements, and weight loss measurements. The lap shear strength of the adhesive was used to evaluate the effects of the bonding process variations.
    Keywords: NONMETALLIC MATERIALS
    Type: International Journal of Adhesion and Adhesives (ISSN 0143-7496); 4; 79-86
    Format: text
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  • 7
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    Preliminary evaluation of hybrid titanium composite laminates (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: In this study, the mechanical response of hybrid titanium composite laminates (HTCL) was evaluated at room and elevated temperatures. Also, the use of an elastic-plastic laminate analysis program for predicting the tensile response from constituent properties was verified. The improvement in mechanical properties achieved by the laminates was assessed by comparing the results of static strength and constant amplitude fatigue tests to those for monolithic titanium sheet. Two HTCL were fabricated with different fiber volume fractions, resin layer thicknesses, and resins. One panel was thicker and was more poorly bonded in comparison to other. Consequently, the former had a lower tensile strength, while fewer cracks grew in this panel and at a slower rate. Both panels showed an improvement in fatigue life of almost two orders of magnitude. The model predictions were also in good agreement with the experimental results for both HTCL panels.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-109095 , NAS 1.15:109095
    Format: application/pdf
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  • 8
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    Evaluation of Ti-6Al-4V surface treatments for use with a polyphenylquinoxaline adhesive (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Three surface treatments for Ti-6Al-4V adherends were evaluated using a thermoplastic polymer monoether polyphenylquinoxaline, MEPPQ, which had been shown in previous studies to have good potential as a high temperature adhesive for aerospace applications. Initial results based on long term thermal exposure at 232 C (450 F) using the phosphate-fluoride (PF) and chromic acid anodized (CAA) treatments with MEPPQ adhesive were not encouraging. A significant improvement in strength retention and a change in failure mode (cohesive) at 232 C (450F) was found for the SHA treated specimens compared to the PF and CAA treatments. Although an improvement in long term thermal durability was obtained with the SHA treatment of Ti-6Al-4V, an improved surface treatment with better long term durability is still required for aerospace applications.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-89045 , NAS 1.15:89045
    Format: application/pdf
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  • 9
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    Adhesive evaluation of thin films of LARC-TPI and LARC-TPI with 5 mol % ODA (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A commercially available LARC-TPI film and an experimentally prepared film of LARC-TPI with 5 mol % of 4,4'-oxydianiline (ODA), designated as LARC-TPI/ODA in the report, supplied by Mitsui Toatsu Chemicals, Incorporated (MTCI), Japan, were evaluated as thermoplastic adhesive films for bonding Ti-6Al-4V. The LARC-TPI/ODA had been shown by MTCI to possess more flow than thermoplastic LARC-TPI and was, therefore, evaluated and compared to the LARC-TPI. Lap shear strength was used to evaluate the materials as adhesives. They were characterized after fracture by determining the glass transition temperature, Tg. The mode of failure was also reported. Thermal exposure at 204C for 500 and 1000 hrs and a 72-hour water-boil were conducted on lap shear specimens prepared with the two adhesive films. Lap shear tests were conducted at RT, 177C, 204C, and 232C before and after exposures.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-87738 , NAS 1.15:87738
    Format: application/pdf
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  • 10
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    A study of oxidation kinetics of nickel metal in flowing air and oxygen-nitrogen mixtures (1964)
    In:  CASI
    Details
    Publication Date: 2019-05-23
    Description: Oxidation kinetics of nickel sheet in flowing air and gas mixtures
    Keywords: MATERIALS, METALLIC
    Type: NASA-TN-D-2224
    Format: application/pdf
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