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Joining NZP ceramics. Final report

Description: Objective was to assess techniques for joining NZP ceramics, a new family of ceramic materials that have low coefficient of thermal expansion, low thermal conductivity, and excellent thermal-shock resistance. Initially, the authors evaluated laser-beam welding over volatile fluxing agents (ferric oxide, copper oxide, boric acid, and boron nitride). They also examined other laser, arc-welding, brazing, and cold joining techniques. The NZP materials were capable of sustaining the thermal stresses associated with these joining processes without substantial cracking. Of the volatile fluxes, only the copper oxide promoted weld fusion. Efforts to accomplish fusion by laser-beam welding over copper, titanium, stainless steel, yttrium barium copper oxide, fused silica glass, and mullite/alumina were unsuccessful. Gas-tungsten arc welding accompanied by porosity, irregularities, and cracking was achieved on copper sheet sandwiched between NZP tiles. Attempts at conventional oxy-acetylene welding and torch brazing were unproductive. Silica-based oxide mixtures and copper oxide-based materials show potential for development into filler materials for furnace brazing, and phosphate-based cements show promise as a means of cold joining.
Date: September 26, 1995
Creator: Nicklas, K.D.; Richey, M.W.; Holcombe, C.E. Jr. & Santella, M.L.
Partner: UNT Libraries Government Documents Department

Environmental microcracking of [NZP] type ceramics

Description: NZP ceramics (sodium zirconium phosphate and its crystal structure analogs) have very low thermal expansion through a large temperature range. Some compositions, with a high degree of thermal expansion anisotropy, are prone to microcracking upon cooling to room temperature. The onset of microcracking is a function of sintering temperature and hence grain size. Subsequent thermal cycling affects the thermal expansion behavior of highly anisotropic compositions due to microcrack healing. Recently it has been determined that this microcracking behavior can be delayed or enhanced by controlling the atmosphere in which the ceramic is heated and cooled. The effects of various atmospheres on the thermal expansion of isotropic and anisotropic [NZP] compositions are presented.
Date: December 31, 1994
Creator: Jackson, T.B. & Porter, W.D.
Partner: UNT Libraries Government Documents Department

SOLUBILITY OF ZIRCONIUM DIBUTYL PHOSPHATE IN SOLVENT EXTRACTION SOLUTIONS

Description: The solubllity of zirconium dibutyl phosphate in aqueous uranyl nitrate and nitric acid solutions was found to vary from 0.35 to 159 rng of zirconium per liter, increasing with increasing uranium concentration. The solubility in 1.126 M TBP in Amsco 125-82 equilibrated with uranyl nitrate-nitric acid aqueous solutions was found to vary from 0.33 to 3.55 g of zirconium per liter. Particularly in the exbactant solutions, the solubillty of zirconium as zirconium dibutyl phosphate is well above the zirconium content of extensively burned natural uranium fuels under Purex process conditions. The zirconium dibutyl phosphate studied was prepared by direct synthesis in aqueous solution and found to have a variable composition. Precipitation from 2 M HNO/sub 3/ at 40 deg C yielded a product which had the approximate composition Zr (OH)(NO/sub 3/)(DBP)/ sub 2/. (auth)
Date: January 20, 1960
Creator: Davis, W. Jr. & Carmichael, H.H.
Partner: UNT Libraries Government Documents Department

Prototype development and testing of ultrafine grain NZP ceramics. Quarterly progress report {number_sign}4, January 28, 1996--April 27, 1996

Description: Caterpillar Inc. continues to develop a slip casting procedure for CMZP (CaMgZr phosphate) exhaust portliners for diesel engines. ZnO was used as additive. Tubes have been cast and fired and initial properties look excellent. 40 lbs of CMZP powder are being prepared for Caterpillar to complete the slip casting of 90 degree elbows.
Date: May 24, 1996
Creator: Brown, J.J.
Partner: UNT Libraries Government Documents Department

Oxidation resistant coatings for ceramic matrix composite components

Description: Corrosion resistant Ca{sub 0.6}Mg{sub 0.4}Zr{sub 4}(PO{sub 4}){sub 6} (CMZP) and Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}(PO{sub 4}){sub 6} (CS-50) coatings for fiber-reinforced SiC-matrix composite heat exchanger tubes have been developed. Aqueous slurries of both oxides were prepared with high solids loading. One coating process consisted of dipping the samples in a slip. A tape casting process has also been created that produced relatively thin and dense coatings covering a large area. A processing technique was developed, utilizing a pre-sintering step, which produced coatings with minimal cracking.
Date: November 1, 1998
Creator: Vaubert, V.M.; Stinton, D.P. & Hirschfeld, D.A.
Partner: UNT Libraries Government Documents Department

Development and testing of spheroidal inorganic sorbents

Description: The general objectives of this task are to develop, prepare, and test spheroidal inorganic ion exchangers made by the HMTA (hexamethylenetetramine) internal gelation process to remove radionuclides and heavy metals from waste streams occurring at the various DOE sites. Inorganic ion-exchange materials, such as sodium silicotitanate, sodium titanate, ammonium molybdeophosphate, phosphotungstic acid, hexacyanoferrates, titanium monohydrogen phosphate, hydrous titanium oxide, polyantimonic acid, magnesium oxide, etc. have high selectivities and efficiencies for separating and removing radionuclides (e.g., cesium, strontium, technetium, iodine, europium, cerium, ruthenium, and zirconium), actinides, and other elements (such as lead, mercury, silver, nickel, zinc, chromium, and fluoride) from aqueous waste streams. The development of cesium specific spherical sorbents for treatment of acidic, high-salt waste solutions was initiated in FY 1998. Acid-side treatment is important at INEEL and could become important if acidic sludge washing were to become a treatment option at Hanford, Savannah River, or Oak Ridge. Zirconium monohydrogen phosphates (ZrHP) embedded with ammonium molybdophosphate (AMP) was the cesium selective inorganic sorbent chosen for making microspheres. AMP is known to be a very effective sorbent for removing cesium from waste streams over a wide range of acidity and salinity, and it has very rapid loading kinetics. The cesium can also be eluted from AMP with ammonium salt solutions. AMP cannot be used as a sorbent at pHs above 7 because it decomposes. In the pH range of 1 to 7, ZrHP is also a very effective sorbent for removing Cs, Sr, Th, U(VI), Pu(IV), AM(III), Hg, and Pb from streams of lower ionic concentrations.
Date: January 29, 1998
Creator: Collins, J.L. & Anderson, K.K.
Partner: UNT Libraries Government Documents Department

Comparison of sodium zirconium phosphate-structured HLW forms and synroc for high-level nuclear waste immobilization

Description: The incorporation of (a) Cs/Sr as simulated heat-generating isotopes contained in Purex reprocessing waste, (b) simulated actinides, and (c) simulated Purex waste in sodium zirconium phosphate (NZP) has been studied. The samples were prepared by sintering, by hot pressing and by hot isostatic pressing in metal bellows containers. The short-term chemical durability of the phosphate-based material containing Purex waste was within an order of magnitude of that for Synroc-C, as measured by 7-day MCC-1 tests at 90{degrees}C. The dissolution behavior showed evidence of re-precipitation phenomena, even after times as short as 28 days. Potential for improvement of NZP-based ceramics for HLW management is discussed. 19 refs., 4 figs., 3 tabs.
Date: December 31, 1996
Creator: Zyryanov, V.N. & Vance, E.R.
Partner: UNT Libraries Government Documents Department

New molecular precursors for low-temperature routes to new oxide materials. Final progress report

Description: In this grant period, the authors have explored the single-source precursor route to silicate materials containing various main group and transition metals. They have also explored the development of polymeric precursors to zinc silicate materials. In addition, they have begun to examine precursors for phosphate materials, based on the di(tert-butyl)phosphate ligand, {minus}O{sub 2}P(O{sup t}Bu){sub 2}. A primary focus of these studies is the development of molecular precursors to homogeneous, ultrapure metal silicates and phosphates. More recently, the authors have attempted to develop template-assisted network-forming reactions that could lead to micro- or mesoporous materials. Findings are summarized below for Zr and HF systems, Al systems, Cr systems, Cu systems, metal phosphate precursors, zinc silicate luminescent materials, and syntheses of inorganic materials using dendrimeric polymers as templates.
Date: October 1, 1997
Creator: Tilley, T.D.
Partner: UNT Libraries Government Documents Department

Prototype development and testing of ultrafine grain NZP ceramics. Final report, July 28, 1995--April 27, 1997

Description: The goal of this project was to demonstrate that a new low-expanding ceramic (Ca{sub 0.6},Mg{sub 0.4})Zr{sub 4}(PO{sub 4}){sub 6}, hereafter referred to as CMZP, could be used as an exhaust manifold liner in off-road diesel engines and provide improved engine efficiency (by permitting higher engine operating temperature). This study has successfully demonstrated this improvement and further engine testing (and possible manufacturing) is presently underway at Caterpillar Inc. Laboratories. Basically this program involved two subcontracts: one to Virginia Tech to develop sintering procedures for CMZP, and one to Caterpillar, Inc. to develop slip casting procedures for CMZP. Nearly 100kg of CMZP were prepared by MATVA, Inc. and Virginia Tech for use by Caterpillar. Virginia Tech developed detailed sintering procedures for CMZP and Caterpillar developed slip casting procedures and manufactured several exhaust manifold elbows. These elbows have been cast into prototype cylinder heads and have been shown to be acceptable replacements for metal manifolds. (Caterpillar advises that a new component may require up to 6 years of testing and qualification before acceptance as standard diesel engine part).
Date: August 4, 1997
Creator: Brown, J.J.
Partner: UNT Libraries Government Documents Department

Development of Spheroidal Inorganic Sorbents for Treatment of Acidic Salt-Bearing Liquid Waste

Description: A spheroidal composite inorganic sorbent was developed for U.S. Department of Energy-Efficient Separations and Processing Crosscutting Program (USDOE-ESP) for potential use in removing radioactive cesium isotopes from acidic high-salt waste streams such as those at Idaho National Engineering and Environmental Laboratory (INEEL). The sorbent, zirconium monohydrogen phosphate (ZrHP) embedded with fine powder of ammonium molybdophosphate (AMP), was prepared using a unique internal gelation process which can be used to make porous reproducible microspheres that are structurally strong, have a low tendency for surface erosion, and improve the flow dynamics for column operations. Both ZrHP and AMP are excellent sorbent materials and, being inorganic, are stable in high radiation fields. AMP is a very effective sorbent for removing cesium from salt-bearing waste streams for a wide range of acidity. In the pH range of 2 to 10, ZrHP is also a very effective sorbent for removing Cs, Sr, Th, U(VI), Pu(IV), Am(III), Hg, and Pb from streams of lower ionic concentrations. Crucial to developing the spheroidal AMP-ZrHP sorbent was to determine the ideal weight percentage of AMP that could be embedded in the ZrHP microspheres in order to maintain the structural integrity of the microspheres and also achieve a good cesium separation. A total of 12 preparations were made. The dry weight percentage of AMP ranged from 30 to 60. Overall, the best composite microspheres prepared contained 50% AMP (by dry weight measurement). Another composite microsphere, which was composed of titanium monohydrogen phosphate (TiHP) embedded with 18 wt % (air-dried weight) potassium cobalt hexacyanoferrate (KCoCF) and developed for a different separations application, was also batch tested for comparison. It proved to be as effective in removing,the cesium as the air-dried AMP (50 wt %)-ZrHP. Granular KCoCF was also prepared and was very effective. Large samples of each of these materials were ...
Date: September 7, 2001
Creator: Collins, J.L.
Partner: UNT Libraries Government Documents Department

Zirconium-titanium phosphate acid catalysts synthesized by sol gel techniques

Description: Recently a large effort has been put into identifying solid acid materials, particularly sulfated zirconia and other sulfated metal oxides, that can be used to replace environmentally hazardous liquid acids in industrial processes. The authors are studying a group of mixed metal phosphates, some of which have also been sulfated, for their catalytic and morphological characteristics. Zirconium and titanium are the metals used in this study and the catalysts are synthesized from alkoxide starting materials with H{sub 3}PO{sub 4}, H{sub 2}O, and sometimes H{sub 2}SO{sub 4} as gelling agents. The measurement of acidity was achieved by using the isomerization of 2-methyl-2-pentene as a model reaction. The phosphate stabilized the mixed metal sulfates, preventing them from calcining to oxides boosting their initial catalytic activity. The addition of sulfate prevented the formation of the catalytically inactive mixed metal pyrophosphates when calcined at high temperatures (> 773 K).
Date: March 1, 1998
Creator: Jackson, N.B.; Thoma, S.G.; Kohler, S. & Nenoff, T.M.
Partner: UNT Libraries Government Documents Department

Prototype development and testing of ultrafine grain NZP ceramics. Quarterly technical progress report No. 3, October 28, 1995--January 27, 1996

Description: Caterpillar has been developing advanced low-heat-rejection (LHR) engine designs because by insulating the combustion chamber components for reduced heat rejection, improved fuel economy and emission reduction can be achieved. The insulation eliminates heat loss during the closed portion of the cycle and increases the combustion temperature. Increased combustion temperatures improve emissions by reducing the amount of particulate or smoke. The higher combustion temperatures also provide additional energy to drive a turbocharger that, in turn, improves the overall efficiency of the engine system and results in increased fuel economy.
Date: February 8, 1996
Creator: Brown, J.J.
Partner: UNT Libraries Government Documents Department

Development and testing of inorganic sorbents made by the internal gelation process for radionuclide and heavy metal separations

Description: The objectives of this task are to develop, prepare, and test microspheres and granular forms of inorganic ion exchangers to remove radionuclides and heavy metals from waste streams occurring at various sites. Several inorganic materials, such as hexacyanoferrates, titanates, phosphates, and oxides have high selectivities and efficiencies for separating and removing radionuclides such as uranium, technetium, cesium, and strontium, and metals such as cobalt, silver, zinc, and zirconium from aqueous waste streams. However, these sorbents frequently exist only as powders and consequently are not readily adaptable to continuous processing such as column chromatography. Making these inorganic ion exchangers as microspheres or granular forms improves the flow dynamics for column operations and expands their practical applications. Microspheres of several materials have been prepared at ORNL, and the effectiveness of zirconium monohydrogen phosphate and hydrous titanium oxide microspheres for removing radionuclides from hot cell waste solutions has been demonstrated.
Date: November 29, 1995
Creator: Egan, B. Z.; Collins, J. L.; Anderson, K. K. & Chase, C. W.
Partner: UNT Libraries Government Documents Department

The effects of thermal cycling on the physical and mechanical properties of [NZP] ceramics

Description: The [NZP] ceramics, sodium zirconium phosphate and its crystal structure analogs, are noted for their very low thermal expansion characteristics. What has not been widely studied is the effect of thermal cycling on physical and mechanical properties. Two [NZP] compositional series were selected (Ba{sub 1+x}Zr{sub 4}P{sub 6{minus}2x}Si{sub 2x}O{sub 24} and Ca{sub 1{minus}x}Sr{sub x}Zr{sub 4}P{sub 6}O{sub 24}) that exhibit varying bulk thermal expansion from positive to negative and varying degrees of thermal expansion anisotropy. The effect of thermal cycling, to 1,250 C, on the bulk thermal expansion and flexural strength of these ceramics is discussed in relationship to changes in density, thermal expansion anisotropy and microstructure.
Date: December 31, 1994
Creator: Jackson, T.B.; Limaye, S.Y. & Porter, W.D.
Partner: UNT Libraries Government Documents Department

Zirconium phosphate waste forms for low-temperature stabilization of cesium-137-containing waste streams

Description: Novel chemically bonded phosphate ceramics are being developed and fabricated for low-temperature stabilization and solidification of waste streams that are not amenable to conventional high-temperature stabilization processes because volatiles are present in the wastes. A composite of zirconium-magnesium phosphate has been developed and shown to stabilize ash waste contaminated with a radioactive surrogate of {sup 137}Cs. Excellent retainment of cesium in the phosphate matrix system was observed in Toxicity Characteristic Leaching Procedure tests. This was attributed to the capture of cesium in the layered zirconium phosphate structure by intercalation ion-exchange reaction. But because zirconium phosphate has low strength, a novel zirconium/magnesium phosphate composite waste form system was developed. The performance of these final waste forms, as indicated by compression strength and durability in aqueous environments, satisfy the regulatory criteria. Test results indicate that zirconium-magnesium-phosphate-based final waste forms present a viable technology for treatment and solidification of cesium-contaminated wastes.
Date: April 1, 1996
Creator: Singh, D.; Wagh, A.S. & Tlustochowicz
Partner: UNT Libraries Government Documents Department

Fourier Transform Photoacoustic Kinetic Spectroscopy of Solid Surfaces. Annual Progress Report, April 1-December 10, 1980

Description: A description of visible Fourier transform photoacoustic spectroscopy (PAS) has been published in two places. Application of PAS to a zirconium phosphate inorganic system has also been described. The use of visible synchrotron radiation in quantitative high frequency PAS has been attempted, and a theoretical modeling of such experiments is nearing completion. A Nicolet FTIR spectrometer is being used to perform mid-infrared PA spectroscopy on carbon samples with a view to determining the best means of ratioing out variations with wavelength in infrared source intensity.
Date: December 1, 1980
Creator: Eyring, E. M.
Partner: UNT Libraries Government Documents Department

High temperature alkali corrosion of dense SiC and Si{sub 3}N{sub 4} coated with CMZP and Mg-DOPED Al{sub 2}TiO{sub 5} in coal gas. Quarterly progress report No. 6, October 1, 1995--December 31, 1995

Description: High temperature alkali corrosion has been known to cause premature failure of ceramic components used in advanced high temperature coal combustion systems such as coal gasification and clean-up, coal fired gas turbines, and high efficiency heat engines. Non-oxide ceramics, such as SiC and Si{sub 3}N{sub 4}, are applied in HITAF systems for their well-known and desirable high temperature thermal and mechanical properties. However, these materials are prone to rapid corrosion under some types of high temperature coal combustion conditions. The objective of this research is to apply CMZP and Mg- Al{sub 2}TiO{sub 5} as coatings to SiC to improve corrosion resistance under coal combustion atmospheres as well as to improve high temperature mechanical properties. The research will not only develop and characterize CMZP and Mg-Al{sub 2}TiO{sub 5} coatings but will also strive to expand the existing knowledge of the mechanism of coal combustion corrosion of SiC in the temperature range of 1000- 4000{degrees}C.
Date: December 31, 1995
Creator: Yang, S. & Brown, J.J.
Partner: UNT Libraries Government Documents Department

Ion-exchange behavior of alkali metals on treated carbons

Description: The ion-exchange behavior of trace quantities of the alkali-metal ions sodium and cesium, on activated carbon impregnated with zirconium phosphate (referred to here as ZrP), was studied. Impregnated carbon had twice as much ion-exchange activity as unimpregnated, oxidized carbon, and 10 times as much as commercial activated carbons. The distribution coefficient of sodium increased with increasing pH; the distribution coefficient of cesium decreased with increasing pH. Sodium and cesium were separated with an electrolytic solution of 0.1 M HCl. Preliminary studies indicated that 0.2 M potassium and cesium can also be separated. Distribution coefficients of the supported ZrP were determined by the elution technique and agreed within 20% of the values for pure ZrP calculated from the literature.
Date: January 1, 1983
Creator: Mohiuddin, G.; Hata, W.Y. & Tolan, J.S.
Partner: UNT Libraries Government Documents Department

Chemically bonded phosphate ceramics for low-level mixed waste stabilization

Description: Novel chemically bonded phosphate ceramics (CBPCs) are being developed and fabricated for low-temperature stabilization and solidification of mixed waste streams which are amenable to conventional high-temperature stabilization processes due to presence of volatiles such as heavy metal chloride and fluorides and/or pyrophorics in the wastes. Phosphates of Mg, Mg-Na and Zr are being developed as candidate matrix materials. In this paper, we present the fabrication procedures of phosphate waste forms using surrogates compositions of three typical mixed wastes streams -- ash, cement sludges, and salts. The performance of the final waste forms such as compression strength, leachability of the contaminants, durability in aqueous environment were conducted. In addition, parameteric studies have been conducted to establish the optimal waste loading in a particular binder system. Based on the results, we present potential applications in the treatment of various mixed waste streams.
Date: December 31, 1994
Creator: Singh, D.; Wagh, A. S.; Cunnane, J. C. & Mayberry, J. L.
Partner: UNT Libraries Government Documents Department

Tribology of improved transformation-toughened ceramics-heat engine test

Description: A short term study has been carried out to evaluate the suitability as cam roller followers of three ceria zirconia toughened aluminas and two yttria stabilized tetragonal zirconias (YTZPs) previously enhanced in programs supported by ORNL. Norton Si{sub 3}N{sub 4} (NBD-100) was also included in this study as a reference material, because it was known from work at Northwestern University that Si{sub 3}N{sub 4} to experienced little or no wear in this application, and NBD-100 is currently a successful commercial bearing material. The tribological studies were subcontracted to the Torrington Company. They found that in cam roller follower simulated tests that there was essentially no wear after 1 hour and 5 hours of testing detectable by weighing and concluded that all of these ceramics are, therefore, candidate materials. Because of the minute amounts of wear it was not possible to identify the wear mechanism or to make any correlations with the other physical properties which were evaluated such as MOR, K{sub IC} hardness, density and grain size. Phase transformation during rolling has been of interest in the tribology of zirconia contain materials. The least stable of the ceria zirconia toughened aluminas resulted in as much as 33% monoclinic phase after testing whereas the yttria stabilized (TTZ) contained very little of this transformed phase. The results of this study show that oxide materials can now be considered as candidates for cam roller followers in heat engines.
Date: April 1, 1992
Creator: Lilley, E.; Rossi, G.A. & Pelletier, P.J. (Norton Co., Northboro, MA (United States). Advanced Ceramics Div.)
Partner: UNT Libraries Government Documents Department