FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W147298774> ?p ?o ?g. }

• W147298774 abstract "Ultra-high-temperature ceramics (UHTC) are a group of materials consisting of zirconium diboride (ZrB2) or hafnium diboride (HfB2) plus silicon carbide (SiC), and in some instances, carbon (C). They offer a combination of properties that make them candidates for airframe leading edges on sharp-bodied reentry vehicles. These UHTCs perform well in the environment for such applications (i.e., air at low pressures). The purpose of this study at the NASA Glenn Research Center was to examine three of these materials under conditions more representative of a propulsion environment: that is, higher oxygen partial pressure and total pressure. Relatively long, multiple-exposure cycles were emphasized. We completed an in-house study of ZrB2 plus 20 vol% SiC (abbreviated as ZS), ZrB2 plus 14 vol% SiC and 30 vol% C (ZSC), and SCS-9a SiC fiber-reinforced ZrB2 plus 20 vol% SiC (ZSS). HfB2-based compositions were not included in the study because of their high cost. The capability of UHTC for propulsion applications must be compared with that of mature, available, and commercially used ceramics such as silicon nitride (e.g., AS-800) to put things in proper perspective. In terms of mechanical properties, UHTCs fall short in terms of strength and fracture toughness. At about 1300 C, the creep resistance of ZS appears to be superior to the creep resistance reported for AS-800. However, the stress rupture life for Si3N4 under stress and temperature conditions similar to those used in this study is measured in hundreds of hours. Because of oxidation, ZS could not achieve such lives. In terms of oxidation resistance, acceptable amounts of material recession in 1 hour to thousands of hours, depending on the specific propulsion application, are on the order of 100 to 300 mm. This converts to an acceptable range of parabolic recession rate constants kp of approximately less than or equal to 10(exp -1) to 10(exp -2) square millimeters per hour for a 1-hr application. For a 100-hr application, an acceptable range of kp would be less than or equal to those values divided by 100. For the more oxidation resistant ZS material, measured parabolic recession rate constants were 4.7 x 10(exp -3) millimeters per hour at 1327 C, 7.8 x 10(exp -2) square millimeters per hour at 1627 C, and 1.3 millimeters per hour at 1927 C. Thus, recession rate constants for ZS are acceptable at 1327 C for a 1-hr application, but here silicon nitride is a superior material. At 1627 C, ZS oxidation is marginal for a 1-hr application, but dimensional growth would be an issue. In a 100-hr application, ZS cannot be considered at any temperature. Our cursory examination of thermal shock, both from a theoretical and experimental viewpoint, indicated that the ZS and ZSC UHTCs are inferior to AS-800 silicon nitride. On the basis of this limited study, UHTCs are not ready to be considered as aeropropulsion materials for any applications longer than a few minutes. Current materials suffer from aggressive oxidation and moisture attack (Quynhgiao Nguyen, NASA Glenn, and Raymond C. Robinson, QSS Group, Inc., Cleveland, OH, 2002, private communication), and they are susceptible to thermal shock. For long-term propulsion applications, major improvements in environmental durability are needed. Work is in progress to improve the oxidation resistance of UHTC materials." @default.
• W147298774 created "2016-06-24" @default.
• W147298774 creator A5016816539 @default.
• W147298774 creator A5022991784 @default.
• W147298774 creator A5034195907 @default.
• W147298774 creator A5071704895 @default.
• W147298774 creator A5077982234 @default.
• W147298774 creator A5079079718 @default.
• W147298774 date "2003-03-01" @default.
• W147298774 modified "2023-09-23" @default.
• W147298774 title "Ultra-High-Temperature Ceramics Evaluated for Aeropropulsion Use" @default.
• W147298774 hasPublicationYear "2003" @default.
• W147298774 type Work @default.
• W147298774 sameAs 147298774 @default.
• W147298774 citedByCount "0" @default.
• W147298774 crossrefType "journal-article" @default.
• W147298774 hasAuthorship W147298774A5016816539 @default.
• W147298774 hasAuthorship W147298774A5022991784 @default.
• W147298774 hasAuthorship W147298774A5034195907 @default.
• W147298774 hasAuthorship W147298774A5071704895 @default.
• W147298774 hasAuthorship W147298774A5077982234 @default.
• W147298774 hasAuthorship W147298774A5079079718 @default.
• W147298774 hasConcept C134132462 @default.
• W147298774 hasConcept C149912024 @default.
• W147298774 hasConcept C159985019 @default.
• W147298774 hasConcept C191897082 @default.
• W147298774 hasConcept C192562407 @default.
• W147298774 hasConcept C2776853252 @default.
• W147298774 hasConcept C2777431650 @default.
• W147298774 hasConcept C2780722187 @default.
• W147298774 hasConcept C5335593 @default.
• W147298774 hasConcept C534791751 @default.
• W147298774 hasConcept C544956773 @default.
• W147298774 hasConcept C546638069 @default.
• W147298774 hasConcept C97549433 @default.
• W147298774 hasConcept C99595764 @default.
• W147298774 hasConceptScore W147298774C134132462 @default.
• W147298774 hasConceptScore W147298774C149912024 @default.
• W147298774 hasConceptScore W147298774C159985019 @default.
• W147298774 hasConceptScore W147298774C191897082 @default.
• W147298774 hasConceptScore W147298774C192562407 @default.
• W147298774 hasConceptScore W147298774C2776853252 @default.
• W147298774 hasConceptScore W147298774C2777431650 @default.
• W147298774 hasConceptScore W147298774C2780722187 @default.
• W147298774 hasConceptScore W147298774C5335593 @default.
• W147298774 hasConceptScore W147298774C534791751 @default.
• W147298774 hasConceptScore W147298774C544956773 @default.
• W147298774 hasConceptScore W147298774C546638069 @default.
• W147298774 hasConceptScore W147298774C97549433 @default.
• W147298774 hasConceptScore W147298774C99595764 @default.
• W147298774 hasLocation W1472987741 @default.
• W147298774 hasOpenAccess W147298774 @default.
• W147298774 hasPrimaryLocation W1472987741 @default.
• W147298774 hasRelatedWork W1974938837 @default.
• W147298774 hasRelatedWork W2065166408 @default.
• W147298774 hasRelatedWork W2125914822 @default.
• W147298774 hasRelatedWork W2169481316 @default.
• W147298774 hasRelatedWork W2272837418 @default.
• W147298774 hasRelatedWork W93459836 @default.
• W147298774 isParatext "false" @default.
• W147298774 isRetracted "false" @default.
• W147298774 magId "147298774" @default.
• W147298774 workType "article" @default.