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Title: Analytical and experimental evaluation of joining silicon carbide to silicon carbide and silicon nitride to silicon nitride for advanced heat engine applications Phase 2. Final report

Abstract

The purpose of joining, Phase 2 was to develop joining technologies for HIP`ed Si{sub 3}N{sub 4} with 4wt% Y{sub 2}O{sub 3} (NCX-5101) and for a siliconized SiC (NT230) for various geometries including: butt joins, curved joins and shaft to disk joins. In addition, more extensive mechanical characterization of silicon nitride joins to enhance the predictive capabilities of the analytical/numerical models for structural components in advanced heat engines was provided. Mechanical evaluation were performed by: flexure strength at 22 C and 1,370 C, stress rupture at 1,370 C, high temperature creep, 22 C tensile testing and spin tests. While the silicon nitride joins were produced with sufficient integrity for many applications, the lower join strength would limit its use in the more severe structural applications. Thus, the silicon carbide join quality was deemed unsatisfactory to advance to more complex, curved geometries. The silicon carbide joining methods covered within this contract, although not entirely successful, have emphasized the need to focus future efforts upon ways to obtain a homogeneous, well sintered parent/join interface prior to siliconization. In conclusion, the improved definition of the silicon carbide joining problem obtained by efforts during this contract have provided avenues for future work that could successfullymore » obtain heat engine quality joins.« less

Authors:
; ; ;  [1]
  1. Norton Co., Northboro, MA (United States). Advanced Ceramics Div.
Publication Date:
Research Org.:
Oak Ridge National Lab., TN (United States); Norton Co., Northboro, MA (United States). Advanced Ceramics Div.
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
28303
Report Number(s):
ORNL/Sub-87-SB045/2
ON: DE95005761; TRN: AHC29510%%108
DOE Contract Number:
AC05-84OR21400
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Oct 1994
Country of Publication:
United States
Language:
English
Subject:
33 ADVANCED PROPULSION SYSTEMS; 36 MATERIALS SCIENCE; SILICON CARBIDES; JOINING; SILICON NITRIDES; HEAT ENGINES; MANUFACTURING; PROGRESS REPORT; MECHANICAL PROPERTIES; MATHEMATICAL MODELS

Citation Formats

Sundberg, G.J., Vartabedian, A.M., Wade, J.A., and White, C.S. Analytical and experimental evaluation of joining silicon carbide to silicon carbide and silicon nitride to silicon nitride for advanced heat engine applications Phase 2. Final report. United States: N. p., 1994. Web. doi:10.2172/28303.
Sundberg, G.J., Vartabedian, A.M., Wade, J.A., & White, C.S. Analytical and experimental evaluation of joining silicon carbide to silicon carbide and silicon nitride to silicon nitride for advanced heat engine applications Phase 2. Final report. United States. doi:10.2172/28303.
Sundberg, G.J., Vartabedian, A.M., Wade, J.A., and White, C.S. Sat . "Analytical and experimental evaluation of joining silicon carbide to silicon carbide and silicon nitride to silicon nitride for advanced heat engine applications Phase 2. Final report". United States. doi:10.2172/28303. https://www.osti.gov/servlets/purl/28303.
@article{osti_28303,
title = {Analytical and experimental evaluation of joining silicon carbide to silicon carbide and silicon nitride to silicon nitride for advanced heat engine applications Phase 2. Final report},
author = {Sundberg, G.J. and Vartabedian, A.M. and Wade, J.A. and White, C.S.},
abstractNote = {The purpose of joining, Phase 2 was to develop joining technologies for HIP`ed Si{sub 3}N{sub 4} with 4wt% Y{sub 2}O{sub 3} (NCX-5101) and for a siliconized SiC (NT230) for various geometries including: butt joins, curved joins and shaft to disk joins. In addition, more extensive mechanical characterization of silicon nitride joins to enhance the predictive capabilities of the analytical/numerical models for structural components in advanced heat engines was provided. Mechanical evaluation were performed by: flexure strength at 22 C and 1,370 C, stress rupture at 1,370 C, high temperature creep, 22 C tensile testing and spin tests. While the silicon nitride joins were produced with sufficient integrity for many applications, the lower join strength would limit its use in the more severe structural applications. Thus, the silicon carbide join quality was deemed unsatisfactory to advance to more complex, curved geometries. The silicon carbide joining methods covered within this contract, although not entirely successful, have emphasized the need to focus future efforts upon ways to obtain a homogeneous, well sintered parent/join interface prior to siliconization. In conclusion, the improved definition of the silicon carbide joining problem obtained by efforts during this contract have provided avenues for future work that could successfully obtain heat engine quality joins.},
doi = {10.2172/28303},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Oct 01 00:00:00 EDT 1994},
month = {Sat Oct 01 00:00:00 EDT 1994}
}

Technical Report:

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  • Techniques were developed to produce reliable silicon nitride to silicon nitride (NCX-5101) curved joins which were used to manufacture spin test specimens as a proof of concept to simulate parts such as a simple rotor. Specimens were machined from the curved joins to measure the following properties of the join interlayer: tensile strength, shear strength, 22 C flexure strength and 1370 C flexure strength. In parallel, extensive silicon nitride tensile creep evaluation of planar butt joins provided a sufficient data base to develop models with accurate predictive capability for different geometries. Analytical models applied satisfactorily to the silicon nitride joinsmore » were Norton's Law for creep strain, a modified Norton's Law internal variable model and the Monkman-Grant relationship for failure modeling. The Theta Projection method was less successful. Attempts were also made to develop planar butt joins of siliconized silicon carbide (NT230).« less
  • This report summarizes the results of Phase 2 of Analytical and Experimental Evaluation of Joining Silicon Nitride to Metal and Silicon Carbide to Metal for Advanced Heat Engine Applications. A general methodology was developed to optimize the joint geometry and material systems for 650{degrees}C applications. Failure criteria were derived to predict the fracture of the braze and ceramic. Extensive finite element analyses (FEA) were performed to examine various joint geometries and to evaluate the affect of different interlayers on the residual stress state. Also, material systems composed of coating materials, interlayers, and braze alloys were developed for the program basedmore » on the chemical stability and strength of the joints during processing, and service. The FEA results were compared with experiments using two methods: (1) an idealized strength relationship of the ceramic, and (2) a probabilistic analysis of the ceramic strength (NASA CARES). The results showed that the measured strength of the joint reached 30--80% of the strength predicted by FEA. Also, potential high-temperature braze alloys were developed and evaluated for the high-temperature application of ceramic-metal joints. 38 tabs, 29 figs, 20 refs.« less
  • Techniques were developed to produce reliable ceramic-ceramic joins and analytical models were developed to predict the mechanical performance of the joins at room and elevated temperatures. Si{sub 3}N{sub 4}-4% Y{sub 2}O{sub 3} (Norton NCX-5100) and {beta}-Sic (Norton NCX-4500) were joined to themselves in the green state prior to final densification. The joins and controls were chemically and mechanically characterized at room and elevated temperatures to prepare the data banks for analytical modeling. Analytical models combining finite element and probabilistic software were developed that are capable of predicting the reliability of the joined components under fast fracture and creep.
  • This report summarizes the results of Phase I of Analytical and Experimental Evaluation of Joining Silicon Nitride to Metal and Silicon Carbide to Metal and Silicon Carbide to Metal for Advanced Heat Engine Applications. A general methodology was developed to optimize the joint geometry and material systems for 650 and 950{degree}C applications. Failure criteria were derived to predict the fracture of the braze and ceramic. Extensive finite element analyses (FEA), using ABAQUS code, were performed to examine various joint geometries and to evaluate the affect of different interlayers on the residual stress state. Also, material systems composed of coating materials,more » interlayers, and braze alloys were developed for the program based on the chemical stability and strength of the joints during processing and service. Finally, the FEA results were compared with experiments using an idealized strength relationship. The results showed that the measured strength of the joint reached 30--90% of the strength by predicted by FEA. Overall results demonstrated that FEA is an effective tool for designing the geometries of ceramic-metal joints and that joining by brazing is a relevant method for advanced heat engine applications. 33 refs., 54 figs., 36 tabs.« less
  • Techniques were developed to produce reliable ceramic-ceramic joins and analytical models were developed to predict the mechanical performance of the joins at room and elevated temperatures. Si{sub 3}N{sub 4}-4% Y{sub 2}O{sub 3} (Norton NCX-5100) and {beta}-Sic (Norton NCX-4500) were joined to themselves in the green state prior to final densification. The joins and controls were chemically and mechanically characterized at room and elevated temperatures to prepare the data banks for analytical modeling. Analytical models combining finite element and probabilistic software were developed that are capable of predicting the reliability of the joined components under fast fracture and creep.