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thermal degradation

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Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001829
EISBN: 978-1-62708-241-9
... Abstract An investigation was conducted to better understand the time-dependent degradation of thermal barrier coated superalloy components in gas turbines. First-stage vanes are normally subjected to the highest gas velocities and temperatures during operation, and were thus the focus...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003550
EISBN: 978-1-62708-180-1
... the failure analysis. The challenge for the analyst then becomes deciding whether the degradation occurred during fabrication of the part or on exposure to an aqueous service environment. Thermal Degradation High molecular weight polymers will also break down upon exposure to elevated temperatures...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006867
EISBN: 978-1-62708-395-9
... that a reduced polymer molecular weight is discovered during failure analysis. The challenge for the analyst then becomes deciding whether the degradation occurred during fabrication of the part or upon exposure to an aqueous service environment. Thermal Degradation High molecular weight polymers...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.auto.c9001901
EISBN: 978-1-62708-218-1
... be an attractive high strength, impact-resistant, and low-moisture-absorbent polymer, thermal degradation processes can readily compromise any of its apparent advantages, as depolymerization dominates over oxidation. The additional presence of acid at or above the continuous service temperature further accelerates...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006920
EISBN: 978-1-62708-395-9
... of moisture or additives. The temperature also determines the state of the polymer (glass transition temperature, melting point). All of these influences affect the structure of a plastic material and thus also its aging behavior. In addition to photodegradation processes, purely thermal degradation processes...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006871
EISBN: 978-1-62708-395-9
...: elevated temperature over a long period of time, elevated temperature over a short period of time, and cyclic exposure to elevated and lowered temperatures, which occurs during alternating day and night exposure. Elevated temperature can lead to an increased rate of thermal degradation. It can also...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001831
EISBN: 978-1-62708-241-9
... and contact surfaces. Chemical and thermal properties of the bearing grease were also examined. The investigation revealed that the failure was caused by wear due to dry friction and impact, both of which worsened as a result of high-temperature degradation of the bearing grease. Fatigue cracks initiated...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.auto.c0090451
EISBN: 978-1-62708-218-1
... Abstract Cracking occurred within the plastic jacket (injection molded from an impact-modified, 15% glass-fiber-reinforced PET resin.) of several assemblies used in a transportation application during an engineering testing regimen which involved cyclic thermal shock (exposing the parts...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006909
EISBN: 978-1-62708-395-9
... chemical decomposition of the polymer, and thermal expansion. The overall degradation process often involves a long induction period during which little degradation is observed ( Ref 1 , 4 , 5 ). At the end of this period, there is a rapid increase in degradation, leading to a significant reduction...
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001109
EISBN: 978-1-62708-214-3
... process. The basic cause of degradation was found to be hot corrosion caused by the deposition of alkali sulfates and chlorides. However this degradation may have been aggravated by thermal cycling and abrasion. The source of the salt was impurities in the flux. Two potential solutions were proposed...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006933
EISBN: 978-1-62708-395-9
...)” indicates that the numerical temperature was determined as the inflection point on the curve. Aging, Degradation, and Thermal History As noted by Sepe ( Ref 6 ), “DSC techniques can be useful in detecting the chemical and morphological changes that accompany aging and degradation.” Semicrystalline...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c0047199
EISBN: 978-1-62708-234-1
... Abstract The lower receiver of the M16 rifle is an anodized forging of aluminum alloy 7075-T6. Degradation of the receivers was observed after three years of service in a hot, humid atmosphere. The affected areas were those in frequent contact with the user's hands. There was no question...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006931
EISBN: 978-1-62708-395-9
... with engineering thermoplastics. However, in practice, small amounts can occur as a result of thermal and oxidative degradation, or, in specific cases, they can be introduced by design in the processing operation. Fig. 2 Basic elements of engineering polymers. See Table 1 for explanation. Basic...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003525
EISBN: 978-1-62708-180-1
... of thermal oxidation, vinyl, vinylene functionality for photooxidation, and hydroxyl group formation indicating hydrolysis ( Ref 4 ). Case studies showing the effectiveness of FTIR in assessing molecular degradation are presented in examples 1 , 13 , and 15 in this article. Chemical Contact...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003555
EISBN: 978-1-62708-180-1
... sensitization stress-corrosion cracking sulfidation thermal barrier coatings WHEN FAILURES OCCUR, the unscheduled outages result in loss of reliability and increased economic costs. A failure investigation can determine the primary cause of material, component, or system degradation. Based...
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001031
EISBN: 978-1-62708-214-3
... caused ductility loss and grain-boundary separation. The excessive oxygen content in the liner was attributed to diffusion from an oxygen-rich environment that had resulted from nonuniform mixing of propellants. The internal oxygen embrittled the alloy and reduced its thermal conductivity, which resulted...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001767
EISBN: 978-1-62708-241-9
..., along with crack networks. Both FTIR and TGA analyses indicated that the surface material was in a highly degraded state, likely due to weathering and thermal and ultraviolet exposure. This, in turn, led to the formation of cracks that propagated under the cyclic forces of vibration and wind...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c9001593
EISBN: 978-1-62708-234-1
... stretched fibrils. Throughout the SEM examination, no signs were found to indicate that post-molding degradation, such as chemical attack or thermal deterioration, had occurred. Fig. 2 Scanning electron image showing brittle fracture features and beach marks suggestive of low cycle fatigue...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c0090460
EISBN: 978-1-62708-234-1
... of molecular degradation caused by the service conditions. Specifically, the part material had undergone severe chemical attack, including oxidation and hydrolysis, through contact with silver chloride. The source of the silver chloride was not established, but one potential source was photographic silver...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001771
EISBN: 978-1-62708-241-9
..., coke readily accumulates on the surface of the tubes, fueling carbon diffusion into the metal and a corresponding degradation in microstructure and loss of ductility at high temperatures. radiant tube stress rupture thermal shock heat resistant steel carbide precipitates SEM-EDS analysis...