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Title: MOLYBDENUM DISILICIDE COMPOSITES FOR GLASS PROCESSING SENSORS

Abstract

No abstract prepared.

Authors:
; ;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
784102
Report Number(s):
LA-UR-01-4365
TRN: AH200137%%121
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Jul 2001
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; GLASS; MOLYBDENUM; LANL

Citation Formats

J. J. PETROVIC, R. G. CASTRO, and ET AL. MOLYBDENUM DISILICIDE COMPOSITES FOR GLASS PROCESSING SENSORS. United States: N. p., 2001. Web.
J. J. PETROVIC, R. G. CASTRO, & ET AL. MOLYBDENUM DISILICIDE COMPOSITES FOR GLASS PROCESSING SENSORS. United States.
J. J. PETROVIC, R. G. CASTRO, and ET AL. Sun . "MOLYBDENUM DISILICIDE COMPOSITES FOR GLASS PROCESSING SENSORS". United States. doi:. https://www.osti.gov/servlets/purl/784102.
@article{osti_784102,
title = {MOLYBDENUM DISILICIDE COMPOSITES FOR GLASS PROCESSING SENSORS},
author = {J. J. PETROVIC and R. G. CASTRO and ET AL},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jul 01 00:00:00 EDT 2001},
month = {Sun Jul 01 00:00:00 EDT 2001}
}

Conference:
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  • The effects of yttria stabilization (0-6 mol%) on the fracture toughness of molybdenum disilicide composites reinforced with 20 vol.% yttria partially stabilized zirconia (Y-PSZ) particles are presented. It is found that the fracture toughness increased from 3.8 MPa{radical}m for the monolithic MoSi{sub 2} to 4.8-5.7 MPa{radical}m for the Y-PSZ reinforced composites. Examinations of the fractured specimens, using optical interference microscopy and laser Raman spectroscopy, showed that the stress-induced martensitic transformation of the Y-PSZ particles occurred only in the plastic wake of the composite stabilized with 2 mol.% yttria. However, the fracture toughness of the 2 mol.% Y-PSZ reinforced composite wasmore » in the same range as those of the other composites which did not exhibit evidence of transformation toughening. The results are rationalized using micromechanical models for the assessment of transformation toughening and microcrack shielding mechanisms.« less
  • The intermetallic compound, molybdenum disilicide (MoSi{sub 2}) is being considered for high temperature structural applications because of its high melting point and superior oxidation resistance at elevated temperatures. The lack of high temperature strength, creep resistance and low temperature ductility has hindered its progress for structural applications. Plasma spraying of coatings and structural components of MoSi{sub 2}-based composites offers an exciting processing alternative to conventional powder processing methods due to superior flexibility and the ability to tailor properties. Laminate, discontinuous and in situ reinforced composites have been produced with secondary reinforcements of Ta, Al{sub 2}O{sub 3}, SiC, Si{sub 3}N{sub 4}more » and Mo{sub 5}Si{sub 3}. Laminate composites, in particular, have been shown to improve the damage tolerance of MoSi{sub 2} during high temperature melting operations. A review of research which as been performed at Los Alamos National Laboratory on plasma spraying of MoSi{sub 2}-based composites to improve low temperature fracture toughness, thermal shock resistance, high temperature strength and creep resistance will be discussed.« less
  • Using platinum coatings on alumina (Al{sub 2}O{sub 3}) sheaths for thermocouples is a widely used practice in the glass industry. Protection of the thermocouple wires and alumina (Al{sub 2}O{sub 3}) sheathing is necessary to avoid corrosion and dissolution of the temperature-sensing unit. The cost associated with providing platinum coatings on the Al{sub 2}O{sub 3} sheath material can be prohibitively high when taking into consideration the infrastructure needed at the glass plants to maintain and secure an inventory of available platinum. There are also issues associated with improving the performance of the platinum coated Al{sub 2}O{sub 3}. The failure rate ofmore » the thermocouples can be as high as 50%. The U.S. glass industry has been in search of alternative materials that can replace platinum and still provide the durability and performance needed to survive in an extremely corrosive glass environment. Investigations by Y.S. Park et al have shown that molybdenum disilicide (MoSi{sub 2}) has similar performance properties in molten glass as some refractory materials that are currently being used in glass processing applications. Molybdenum disilicide is a candidate high temperature material for such applications because of its high melting temperature (2030 C), relative low density (6.24g/cm{sup 3}), high thermal conductivity (52 W/mK), a brittle to ductile transition near 1000 C, and stability in a variety of corrosive and oxidative environments. Additionally, the cost of MoSi{sub 2} is significantly lower as compared to platinum coatings. Plasma spraying has been shown to be a very effective method for producing coatings and spray formed components of MoSi{sub 2} and MoSi{sub 2} composites. Investigations on plasma spray formed MoSi{sub 2}-Al{sub 2}O{sub 3} composite gas injection tubes were shown to have enhanced high temperature thermal shock resistance when immersed in molten copper and aluminum. The composite tubes outperformed high-grade graphite and Sic tubes when immersed in molten copper and had similar performance to high-density graphite and mullite when immersed in molten aluminum. Energy absorbing mechanisms such as debonding (between the MoSi{sub 2} and Al{sub 2}O{sub 3} layers) and microcracking in the Al{sub 2}O{sub 3} layer contributed to the composites ability to absorb thermal stresses and strain energy during the performance test. Molybdenum disilicide and alumina are chemically compatible and have similar thermal expansion coefficients.« less
  • Sensors for measuring the properties of molten glass require protective sensor sheaths in order to shield them from the extremely corrosive molten glass environment. MoSi{sub 2} has been shown to possess excellent corrosion resistance in molten glass, making it a candidate material for advanced sensor sheath applications. MoSi{sub 2}-coated Al{sub 2}O{sub 3} tubes, MoSi{sub 2}-Al{sub 2}O{sub 3} laminate composite tubes, and MoSi{sub 2}-Al{sub 2}O{sub 3} functionally graded composite tubes have been produced by plasma spray-forming techniques for such applications.
  • Materials research is needed to improve the performance of high temperature materials that must withstand the hostile environment of the glassmaking process and to improve the operating efficiency. Advances in materials used for sensors and controls is perhaps one of the most important requirements for improving the efficiency of the glass production process. The use of molybdenum disilicide (MoSi{sub 2}) based materials, which are corrosion resistant in glass, are being investigated for improving the performance of advance temperature sensors. Using advanced plasma spray forming techniques, laminate and functionally graded composite tubes of MoSi{sub 2} and Al{sub 2}O{sub 3} are beingmore » developed to protect advanced temperature sensors from the hostile environment of the glassmaking process.« less