zircon carburation studies: Topics by WorldWideScience.org

Study of age hardening behavior of Al-4.5wt%Cu/zircon sand composite in different quenching media - A comparative study

Characteristics of lead-zirconate-titanate (PZT) elements were studied by directly irradiating them with a 400 MeV/n Xe beam. The elements were sensitive to 10{sup 4} Xe ions and their output amplitudes were proportional to the beam intensity. An ensemble of those output amplitudes displayed a Bragg-curve-like response towards the range of 400 MeV/n Xe ion. We discuss the potential of PZT elements as a radiation detector and their application to high-intensity and high-energy detectors. (author)

2003-03-01

2

British Library Electronic Table of Contents (United Kingdom)

The age hardening behavior of Al-4.5%Cu alloy composite reinforced with zircon sand particulates and produced by stir casting route has been investigated in different quenching media viz, water, oil, and salt brine solution (7wt%). Optical microscopy of the as cast alloy composite indicates that the matrix of the composite has the cellular structure. Copper rich CuAl2 precipitates have been found near particle matrix interface. The results of ageing demonstrate that the microhardness of age hardenable Al-Cu based alloy composites depend on the quenching medium in which they are heat treated. Salt brine quenching is faster as compared to water and oil, even if higher strength is obtained but cannot be used for complex shapes and thin sections where oil quenching is the alternative due to mi...

2009-01-01

3

Sintering of nano-sized WC-Co powders produced by a gas reduction-carburization process

Sintering of nano-sized WC-Co powders produced by a gas reduction-carburization process

Nanocrystalline cemented tungsten carbide has attracted considerable interests for use in cutting tool because of its superior mechanical properties. In this study, nano-sized powders of mixed WC and Co were prepared from attrition-milled oxides by a gas reduction-carburization process. The effects of compacting pressure, heating schedule, additional ball-milling, and the presence of a grain growth inhibitor on the sintering properties of the nano-sized WC-Co powders were examined. The grain size and phases in WC-Co alloy were clearly affected by compacting pressure. Because of the trapped gases and the lower melting point of the cobalt binder, when a compact of nano-sized WC-Co powder was sintered through a heating schedule with holding steps, the sintered alloy maintained the small size of WC grains without any {eta} phase. In addition, the additional ball-milling improved the microstructure and mechanical properties of the nano-sized WC-Co ...

2006-08-10

4

EDDY CURRENT SIZING OF CASE DEPTH IN BEARING ...

Nanocrystalline cemented tungsten carbide has attracted considerable interests for use in cutting tool because of its superior mechanical properties. In this study, nano-sized powders of mixed WC and Co were prepared from attrition-milled oxides by a gas reduction-carburization process. The effects of compacting pressure, heating schedule, additional ball-milling, and the presence of a grain growth inhibitor on the sintering properties of the nano-sized WC-Co powders were examined. The grain size and phases in WC-Co alloy were clearly affected by compacting pressure. Because of the trapped gases and the lower melting point of the cobalt binder, when a compact of nano-sized WC-Co powder was sintered through a heating schedule with holding steps, the sintered alloy maintained the small size of WC grains without any #eta# phase. In addition, the additional ball-milling improved the microstructure and mechanical properties of the nano-sized WC-Co ...

2006-08-10

5

Crystal field and EPR studies of Nd{sup 3+}:YMO{sub 4}(M=V,AS,P)

... HARDENED CUP AND CARBURIZED AND HARDENED CORES HAVE BEEN PROFILED USING 2 TYPES OF EDDY CURRENT PROBES. ...

1986-07-01

6

Crystal field and EPR studies of Nd"3"+:YMO_4(M=V,AS,P)

Crystal field calculation and electron paramagnetic resonance (EPR) have been performed on zircon-type materials Nd:YMO{sub 4} (M=V, As, P). Simulation of the energy level schemes has been carried out and the wave functions composition and g tensor principal values associated to the first sub-level of the {sup 4}I{sub 9/2} manifold were calculated. A rather good correlation is obtained between crystal field calculations and the EPR measurements. Furthermore, some extra lines observed by optical spectroscopy (absorption and emission) also appear on the EPR spectra and a correlation between the two spectroscopies indicates that Nd{sup 3+}-Nd{sup 3+} exchange and dipolar interactions occur in the zircon family, even at very low doping content (less than 8 x 10{sup 19} Nd{sup 3+} ions cm{sup -3}). Nd{sup 3+}-Nd{sup 3+} pairs at distances 3.9, 5.9 and 6.3 A have been identified. (orig.) 13 refs.

1998-07-24

7

Surface durability of WC/C-coated case-hardened steel gear

Crystal field calculation and electron paramagnetic resonance (EPR) have been performed on zircon-type materials Nd:YMO_4 (M=V, As, P). Simulation of the energy level schemes has been carried out and the wave functions composition and g tensor principal values associated to the first sub-level of the "4I_9_/_2 manifold were calculated. A rather good correlation is obtained between crystal field calculations and the EPR measurements. Furthermore, some extra lines observed by optical spectroscopy (absorption and emission) also appear on the EPR spectra and a correlation between the two spectroscopies indicates that Nd"3"+-Nd"3"+ exchange and dipolar interactions occur in the zircon family, even at very low doping content (less than 8 x 10"1"9 Nd"3"+ ions cm"-"3). Nd"3"+-Nd"3"+ pairs at distances 3.9, 5.9 and 6.3 A have been identified. (orig.)

1998-07-24

8

British Library Electronic Table of Contents (United Kingdom)

The purpose of this study is to investigate the influence of tungsten carbide/carbon (WC/C) coating on the surface durability of casehardened steel gear. Two kinds of WC/C coatings were deposited on the ground gear pair made of chromium molybdenum steel with carburizing and quenching. One is the conventional WC/C coating, and the other is WC/C coating with about 1 ?m CrN interlayer. Here, the WC/C-coated test pinion and the WC/C-coated one with CrN interlayer are represented by WT and ST, respectively. Non-coated test pinion is represented by NT. The surface roughness along the tooth profile direction of WT and ST was almost the same as that of NT. A spur gear test was carried out with an IAE power circulating type gear test rig under EP gear oil lubricating condition. The fatal failure mo...

2010-01-01

9

Ion nitriding; Proceedings of the International Conference, Cleveland, OH, Sept. 15-17, 1986

Microprocessor system controlling gas-carburizing process

The present conference discusses plasma-assisted surface coating/modification processes, the applications to date of ion nitriding, the effects of nitrogen on metal surfaces, ion nitriding mechanisms in Cr, Al and Cr + Al-containing 1040 steel, ion nitriding of Al and its alloys, life enhancement for forging dies, novel anode plasma nitriding developments, and a comparative study of the pulsed and dc ion-nitriding behavior in specimens with blind holes. Also discussed are the influence of heating method on ion nitriding, surface hardening of marage steels by ion nitriding without core hardness reduction, plasma nitriding of nodular cast iron sput gears, NbN composites for superconductors, the carburization of tungsten in a glow discharge methane plasma, economic considerations concerning plasma nitriding, and the corrosion properties obtained by ion nitriding.

1987-01-01

10

Petrography, geochemistry and regional significance of crystalline klippen in the Garhwal Lesser Himalaya, India

This report introduces a microprocessor system composed of a Z-80 single-board computer controlling a gas-carburizing process. The system has 7 analogical input and output signals 24 switch signal-input and 12 switch signal-output signals, which are applicable for temperature, carbon potential, and mechanical-movement control of multipurpose sealed furnaces, or for mutiple-zone temperature, carbon potential, and mechanical-movement control of continuous gas carburizing furnaces; or for distributed control of pit-type carburizing furnaces. The setpoints of variables, such as treating time, temperature, carbon potential of carburizing period, carbon potential of diffusion period, depth of carburizing layer, P.I.D. etc., are entered by keyboard and stored into memories, and actual values are displayed by digital tubes. Furthermore, the fault of thermocouple, oxygen probe, or infrared ...

1986-01-01

11

British Library Electronic Table of Contents (United Kingdom)

Uphalda gneisses (UG) is a crystalline klippe located near Srinagar in Garhwal Himalaya. These gneisses are compared with Debguru porphyroids (DP) (?Ramgarh group) of Garhwal?Kumaun Himalaya and Baragaon mylonitic gneisses (BMG) of Himachal Himalaya. Petrographic study reveals that the deformation of UG was initiated at higher temperature (above 350?C) and continued till lowering of temperature and deformation led to the mylonitization. Geochemically, these granitic gneisses (UG, DP and BMG) exhibit similar composition. Features such as high molecular A/CNK value (>1), presence of normative corundum and absence of normative diopside, enhanced Rb/Sr, Rb/Zr ratios, enrichment of Th and containing rounded zircons support their crustally-derived S-type granitic nature. The linear plot in major...

2011-01-01

12

Memory of multiple aging stages above the freezing temperature in the Relaxor ferroelectric PLZT.

In situ isotopic analyses of U and Pb in zircon by remotely operated SHRIMP II, and Hf by LA-ICP-MS: an example of dating and genetic evolution of zircon by 176Hf/177Hf from the Ita Quarry in the Atuba Complex, SE, Brazil

The dynamic dielectric susceptibility and the elastic compliance of the relaxor ferroelectric lanthanum lead zirconate titanate (PLZT) 9/65/35 have been measured under different cooling and heating protocols in order to study aging and memory. The memory of multiple aging stages at different temperatures has been found (several dips in the susceptibility curves on heating), as in spin glass systems below the glass transition. Remarkably, in PLZT the memory of several aging stages is retained also above the freezing temperature deduced from the dynamic susceptibilities. The results are discussed in light of the existing models of aging and memory in spin and dipolar glasses. PMID:15447139

2004-08-24

13

The Study of Phosphors Efficiency and Homogeneity using a Nuclear Microprobe

Remotely-operated SHRIMP dating of zircon is an interesting alternative for dating of zircon crystals. Although it does not represent any technical progress of the geochronological method using the U-Pb system in zircon it is a very useful and cheap facility. The procedure was first used for mass spectrometric analyses involving two international laboratories in Sao Paulo, Brazil and Beijing, China. It was applied to samples of three gneiss-migmatitic rocks from the Ita quarry in the Atuba Complex (located between the Luis Alves and the Apiai Domain) to test previous controversial hypotheses about its evolution. The presence of important archaean and paleo proterozoic components in the complex is confirmed by analyses of zircon found in probably neo proterozoic leucosomes. Diorite intrusion also occurred during the neo proterozoic, associated with the 0.6Ga continental collisions involved in the ...

2009-10-01

14

Fabrication of zircon for disposition of weapons plutonium

Ion Beam Induced Luminescence (IBIL) and Ion Beam Induced Charge Collection (IBICC) have been applied in the study of the luminescence emission efficiency and investigation of the homogeneity of the luminescence emission in phosphors. The IBIL imaging was performed by using sharply focused ion beams or broad/partially-focused ion beams. The luminescence emission homogeneity in samples was examined to reveal possible distributed crystal-defects that may lead to the inhomogeneity of the luminescence emission in samples.The purpose of the study is to search for suitable luminescent thin films that have high homogeneity of luminescence emission, large IBIL efficiency under heavy ion excitation, and can be placed as a thin layer on the top of microelectronic devices to be analyzed with Ion Photon Emission Microscopy (IPEM). The emission yield was found to be low for organic materials, due to saturation of the light output dependence on the energy ...

2000-12-08

15

The influence of Ar gas in the nitriding of low temperature plasma carburized AISI304L stainless steel

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). In an effort to address the problems of long term storage and nuclear waste minimization, zircon has been proposed as a host medium for plutonium and other actinides recovered from dismantled nuclear weapons. The objective of this work is to investigate the feasibility of large scale fabrication of Pu-bearing zircon. Since PuO_2 is thermodynamically less stable than ZrO_2, it is expected that the process parameters determined for synthesizing ZrSiO_4 (zircon) would be applicable to those for PuSiO_4 (Pu-zircon). Furthermore, since the foremost concern in plutonium processing is the potential for contamination release, this work emphasizes the development of process parameters, using zircon first, to anticipate potential material problems ...

16

The Influence of CH_4 Gas Addition in the Nitriding of Low Temperature Plasma Carburized AISI304L Stainless Steel

Conventional plasma carburizing or nitriding for austenitic stainless steels results in a degradation of corrosion resistance. However, a low temperature plasma surface treatment can improve surface hardness without deteriorating the corrosion resistance. The 2-step low temperature plasma processes (the combined carburizing and post nitriding) offers the increase of both surface hardness and thickness of hardened layer and corrosion resistance than the individually processed low temperature nitriding and low temperature carburizing techniques. In the present paper, attempts have been made to investigate the influence of the introduction of Ar gas (0#approx#20%) in nitriding atmosphere during low temperature plasma nitriding at 370 .deg. C after low temperature plasma carburizing at 470 .deg. C. All treated specimens exhibited the increase of the surface hardness with increasing Ar level in the ...

2008-03-01

17

Phenomenological studies on structure and elemental composition of nanosecond and femtosecond laser-generated aerosols with implications on laser ablation inductively coupled plasma mass spectrometry

The effects of CH_4 content at nitriding step in the low temperature two-step plasma treatment (carburizing+nitriding) on the surface characteristics of AISI304L stainless steel were investigated. The low temperature plasma carburizing was carried out at 550 .deg. C for 5h in a gas mixture of H_2 Ar and CH_4. The thickness of a carburized layer increased up to about 30 #mu#m and corrosion resistance of the layer decreased due to the precipitation formed at the grain boundary. After carburizing, a low temperature plasma nitriding was subsequently performed in the same chamber at 400 .deg. C for 15h to improve corrosion resistance and to further increase the surface hardness. The surface hardness of a N-enriched layer after nitriding reached up to 1,200HV_0_._1, which is much higher than that of as-carburized layer(750 HV_0_._1). The post nitriding process had a beneficial effect on ...

2007-10-01

18

Fluorimetric determination of uranium in certain refractory minerals, environmental samples and industrial waste materials

In laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), the properties of laser-generated aerosols, such as size and composition, are crucial for matrix-independent quantification. In this study, the aerosol particle morphology and elemental composition generated by two state-of-the-art laser systems (ArF excimer nanosecond-UV laser and Ti:sapphire femtosecond-IR laser) were investigated by electron microscopic techniques. Electrostatic sampling of the aerosols directly onto transmission electron microscopy (TEM) grids allowed us to study the morphology and elemental composition of the aerosols using TEM and TEM-EDX (energy dispersive X-ray spectroscopy) analyses, respectively. The results of the electron microscopic studies were finally compared to the LA-ICPMS signals of the main matrix components. The investigations were carried out for non-conducting materials (glass and zircon), ...

19

Method for the reduction of radioactivity of some building materials

A simple sample decomposition and laser fluorimetric determination of uranium at trace level is reported in certain refractory minerals, like ilmenite, rutile, zircon and monazite; environmental samples viz. soil and sediments; industrial waste materials, such as, coal fly ash and red mud. Ilmenite sample is decomposed by heating with ammonium fluoride. Rutile, zircon and monazite minerals are decomposed by fusion using a mixture of potassium bifluoride and sodium fluoride. Environmental and industrial waste materials are brought into solution by treating with a mixture of hydrofluoric and nitric acids. The laser induced fluorimetric determination of uranium is carried out directly in rutile, zircon and in monazite minerals and after separation in other samples. The determination limit was 1 #mu#g x g"-"1 for ilmenite, soil, sediment, coal fly ash and red mud samples, and it is 5 #mu#g x g"-"1 for rutile, ...

2005-10-01

20

Electrolytic plasma processing of steel surfaces

A few industry-derived and conventional building materials have above acceptable radioactivity. An examination of some materials presently used, or with a potential for use, has shown that in phosphogypsum, fly ash, zircon kyanite tailings, red mud and brickmaking clay, the radium equivalent activities of the finer fractions (<53 #mu#) are higher than those of the larger fractions. Consequently, the radioactivity of these materials could be reduced by dry-sieving and discarding the fines. In blast furnace slag and dissociated zircon, no such reduction would occur since the radioactivity is evenly distributed in all sized fractions.

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Caburization kinetics of alloy-800 in liquid sodium at 550_0C

The thermo-chemical treatments of steels with plasma is normally carried out in low-pressure ionized gaseous atmospheres. Among the treatments used most often are: nitruration, carburization and boronized. A plasma can also generate at atmospheric pressure. One way to produce it is with an electrochemical cell that works at a relatively high inter-electrode voltage and under conditions of heavy gas generation. This type of plasma is known as electrolytic plasma. This work studies the feasibility of using electrolytic plasma for the surface processing of steels. Two processes were selected: boronized and nitruration., for the hardening of two types of steel: one with low carbon (1020) and one with low alloy (4140). In the case of the nitruration, the 1020 steel was first aluminized. The electrolytes were aqueous solutions of borax for the boronizing and urea for the nitruration. The electrolytic plasmas were classified qualitatively, in relation ...

2006-12-01

22

WASTE SOLIDIFICATION BUILDING BENCH SCALE HIGH ACTIVITY WASTE SIMULANT VARIABILITY STUDY FY2008

Preliminary observations on the isothermal carbon transfer in low-carbon Alloy-800 exposed in sodium with AISI-304 type of steel at 550_0 are reported. The alloy was found to undergo a carburization comparable or slightly lower than that observed for the AISI-304 stainless steel for carbon activities above 6 x 10 /sup -3/ at 550_0C, but was not found to decarburize below such a carbon activity value. In the examined range the chemical composition of the alloys does not affect the process out of the experimental uncertainty of measure. Conclusions concerning the effective diffusion for carbon in the alloy are formulated. Preliminary relationships were found for an empirical evaluation of the carburization of the Alloy-800 in sodium of known carbon activity.

23

The development perspectives of the alternative fuels; Les perspectives de developpement des carburants alternatifs en France

The primary objective of this task was to perform a variability study of the high activity waste (HAW) acidic feed to determine the impact of feed variability on the quality of the final grout and on the mixability of the salt solution into the dry powders. The HAW acidic feeds were processed through the neutralization/pH process, targeting a final pH of 12. These fluids were then blended with the dry materials to make the final waste forms. A secondary objective was to determine if elemental substitution for cost prohibitive or toxic elements in the simulant affects the mixing response, thus providing a more economical simulant for use in full scale tests. Though not an objective, the HAW simulant used in the full scale tests was also tested and compared to the results from this task. A statistically designed test matrix was developed based on the maximum molarity inputs used to make the acidic solutions. The maximum molarity inputs were: 7.39 HNO{sub 3}, 0.11618 ...

2009-03-20

24

Optical image storage in ion implanted PLZT ceramics

The petroleum and petroleum products increase offer a real development opportunity to the alternative fuels. In the context of the french energy accounting increase, the energy independence notion incites the government to promote these new fuels. If the LPG seems declining because of the accident risks fear, the fuel cell is not for today. Near these two sectors what is the future of the biofuels and the natural gas vehicle or the electric cars? (A.L.B.)

2006-06-15

25

Emplacement ages of Jurassic-Cretaceous South African kimberlites by the Rb-Sr method on phlogopite and whole-rock samples

We have demonstrated that optical images can be stored in transparent lead-lanthanum-zirconate-titanate (PLZT) ceramics by exposure to near-UV light with photon energies greater than the band gap energy of approx. equal to 3.35 eV. The image storage process relies on optically induced changes in the switching properties of ferroelectric domains (photoferroelectric effect). Stored images are nonvolatile but can be erased by uniform UV illumination and simultaneous application of an electric field. Although high quality images, with contrast variations of >= 100:1 and spatial resolution of approx. equal to 10 #mu#m, can be stored using the photoferroelectric effect, relatively high exposure energies (approx. equal to 100 mJ/cm"2) are required to store these images. This large exposure energy severely limits the range of possible applications of nonvolatile image storage in PLZT ceramics. We have recently found from studies of H, He and Ar ...

26

Effects of processing time and temperature on the surface properties of AISI 316L stainless steel during low temperature plasma nitriding after low temperature plasma carburizing

Rb-Sr phlogopite age determinations, interpreted as emplacement ages, are reported for 15 southern African kimberlites. Jagersfontein and Rietfontein (85 and 95 Ma) have ages typical of the majority of well-known Cretaceous kimberlites, whereas somewhat older ages of about 118 to 125 Ma have been obtained for localities in the Postmasburg, Barkly West and Boshoff districts. Previous zircon ages of 90Ma for Finsch and Roberts Victor are believed to be incorrect. Two other localities in the Barkly West area have significantly younger emplacement ages of about 114 Ma relative to most Barkly West occurrences. Two off-craton kimberlites, Uintjiesberg and Mzongwana, are 100 and 150 Ma in age respectively. Swartruggens and Elandskloof have ages of 150-160 and 165 Ma respectively. A Barkly West occurrence, Klipfontein, also has an apparent age of 160 Ma, but this result cannot be considered reliable. The emplacement ages and initial "8"7Sr/"8"6Sr ratios of southern African ...

27

Carburization and tensile behavior of alloy 800 in liquid sodium

The 2-step low temperature plasma processes (the combined carburizing and post-nitriding) were carried out for improving both the surface hardness and corrosion resistance of AISI 316L stainless steel. The effects of processing time and temperature on the surface properties during nitriding step were investigated. The expanded austenite (#gamma#N)was formed on all of the treated surface. The thickness of #gamma#N was increased up to about 20 #mu#m and the thickness of entire hardened layer was determined to be about 40 #mu#m. The surface hardness reached up to 1,200 HV_0_._1 which is about 5 times higher than that of untreated sample (250 HV_0_._1). The thickness of #gamma#N and concentration of N on the surface were increased with increasing processing time and temperature. The corrosion resistance in 2-step low temperature plasma processed austenitic stainless steels was enhanced more than that in the untreated austenitic stainless steels due to a high ...

2008-06-01

28

Carburization and tensile behavior of Alloy 800 in liquid sodium

The carbon transfer has been analyzed in the Alloy 800/sodium/stainless steel system by determining the carbon-uptake of Alloy 800 foils, which were exposed in liquid sodium of known carburizing potential. Under equilibrium condistions between 650 and 550_0C the measured total carbon concentrations in the Alloy 800 tabs were found to be roughly related to the carbon activities of the sodium environment by the equation already stated for the 18 Cr-8/10 Ni stainless steels, extrapolated to the chemical composition of the Ni-rich austenitic alloy. However the Alloy 800 was not found to undergo any decarburization in low-carbon activity environments. The carbon diffusion kinetics was determined as a function of temperature, it was found to be similar to that reported for the AISI-304 type of steel. The effects of sodium exposure on microstructural and mechanical properties of several Alloy 800 heats were examined at 550_0C as a function of the active carbon ...

29

Testing of 12Kh18N10T tube steel samples tendency to intergranular corrosion

The carbon transfer has been analyzed in the Alloy 800/sodium/stainless steel system by determining the carbon-uptake of Alloy 800 foils, which were exposed in liquid sodium of known carburizing potential. Under equilibrium conditions between 650 and 550/sup 0/C the measured total carbon concentrations in the Alloy 800 tabs were found to be roughly related to the carbon activities of the sodium environment by the equation already stated for the 18 Cr-8/10 Ni stainless steels, extrapolated to the chemical composition of the Ni-rich austenitic alloy. However the Alloy 800 was not found to undergo any decarburization in low-carbon activity environments. The carbon diffusion kinetics was determined as a function of temperature, it was found to be similar to that reported for the AISI-304 type of steel. The effects of sodium exposure on microstructural and mechanical properties of several Alloy 800 heats were examined at 550/sup 0/C as a function of the active carbon ...

1983-05-01

30

Experimental and theoretical analysis of compression ratio on Otto-cycle engines. Pt. 1

Tendency of 12Kh18N10T steel tube samples to intergranular corrosion (IGC) is investigated by an express electrochemical method in the 10% solution of H_2SO_4+0.0025 g/l of KCNS. Tendency to IGC is mainly detected on the internal surface of tube samples. It is shown that the tendency to INC under plant conditions is caused by surface carburization under its incomplete purification from the graphite lubrication.

1993-01-01

31

Thermodynamics of reactions of chemically stable ceramics formation

The increase of the compression ratio of Otto carburator engines up to epsilon = 14 was investigated by Audi in its research department at Neckarsulm. The results are presented in three partial reports. Part one describes the Audi fuel method and demonstrates the effects of the main parameters. Part two shows the influence of the current on the combustion by the help of a new measuring method developed by the Institut fuer Physikalische Elektronik at Stuttgart University. Part three provides a theoretical analysis of the data gained in the investigations.

1982-01-01

32

Method of bistable optical information storage using antiferroelectric phase PLZT ceramics

Theoretical thermodynamical calculations for the ZrO/sub 2/- Al/sub 2/O/sub 3/-SiO/sub 2/ system are given to expose the regions of the most chemically stable products of crystallization. It is established that ceramics on the base of mullite with zircon addition and containing the minimum quantity of glass phase should be preferably used in chemical media containing HCl.

1981-06-01

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Influence of lanthanum (x) concentration on the properties of x/65/35 PLZT electroceramics

A method for bistable storage of binary optical information includes an antiferroelectric (AFE) lead lanthanum zirconate titanate (PLZT) layer having a stable antiferroelectric first phase and a ferroelectric (FE) second phase obtained by applying a switching electric field across the surface of the device. Optical information is stored by illuminating selected portions of the layer to photoactivate an FE to AFE transition in those portions. Erasure of the stored information is obtained by reapplying the switching field.

1990-01-01

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Geological evolution of the center-southern portion of the Guyana shield based on the geochemical, geochronological and isotopic studies of paleoproterozoic granitoids from southeastern Roraima, Brazil; Evolucao geologica da porcao centro-sul do escudo das Guianas com base no estudo geoquimico, geocronologico e isotopico dos granitoides paleoproterozoicos do sudeste de Roraima, Brasil

Lead lanthanum zirconate titanate (PLZT) nanopowders with chemical compositions x/65/35 PLZT (x = 6 - 10 mol%) were prepared by sol-gel method. PLZT ceramics was obtained by the conventional sintering method and utilizing the hot pressing method. The investigations of dielectric and ferroelectric measurements of as obtained PLZT ceramics have revealed the influence of lanthanum concentration on the properties of PLZT electroceramics. (author)

2003-09-25

35

Early cretaceous age of orthogneiss from the Charleston Metamorphic Group, New Zealand

This study focuses the granitoids of center-southern portion of Guyana Shield, southeastern Roraima, Brazil. The region is characterized by two tectonic-stratigraphic domains, named as Central Guyana (GCD) and Uatuma-Anaua (UAD) and located probably in the limits of geochronological provinces (e.g. Ventuari-Tapajos or Tapajos-Parima, Central Amazonian and Maroni-Itacaiunas or Transamazon). The aim this doctoral thesis is to provide new petrological and lithostratigraphic constraints on the granitoid rocks and contribute to a better understanding of the origin and geo dynamic evolution of Guyana Shield. The GCD is only locally studied near to the UAD boundary, and new geological data and two single zircon Pb-evaporation ages in mylonitic biotite granodiorite (1.89 Ga) and foliated hastingsite-biotite granite (1.72 Ga) are presented. These ages of the protholiths contrast with the lithostratigraphic picture in the other areas ...

2006-07-01

36

Develop techniques for ion implantation of PLZT [lead-lanthanum-zirconate-titanate] for adaptive optics

Discordant U-Pb zircon isotopic data from amphibolite facies orthogneisses of the Charleston Metamorphic Group, western South Island, New Zealand, define a lower intercept age of 114#+-#18 m.y. that is interpreted as the crystallization age of the orthogneiss magmas. The upper intercept age of 1026#+-#97 m.y. reflects inherited components of Precambrian zircon derived from the source region of the magmas. The age, and whole rock chemical characteristics, indicate that the orthogneisses are part of the same phase of Early cretaceous magmatic activity that produced voluminous arc-related calc-alkaline plutonic rocks throughout western South Island. Previously published K-Ar and Rb-Sr mineral ages indicate uplift and cooling of the Charleston Metamorphic Group to less than 400deg C by 110-90 m.y. This uplift occurred as a consequence of low-angle normal faulting related to the Late Cretaceous breakup of Gondwana, and suggests that regional ...

37

Uranium-lead zircon ages from the Median Tectonic Zone, New Zealand

Research was conducted at Pacific Northwest Laboratory to develop high photosensitivity adaptive optical elements utilizing ion implanted lanthanum-doped lead-zirconate-titanate (PLZT). One centimeter square samples were prepared by implanting ferroelectric and anti-ferroelectric PLZT with a variety of species or combinations of species. These included Ne, O, Ni, Ne/Cr, Ne/Al, Ne/Ni, Ne/O, and Ni/O, at a variety of energies and fluences. An indium-tin oxide (ITO) electrode coating was designed to give a balance of high conductivity and optical transmission at near uv to near ir wavelengths. Samples were characterized for photosensitivity; implanted layer thickness, index of refraction, and density; electrode (ITO) conductivity; and in some cases, residual stress curvature. Thin film anti-ferroelectric PLZT was deposited in a preliminary experiment. The structure was amorphous with x-ray diffraction showing the beginnings of a structure at substrate temperatures of ...

38

PLZT electrooptic shutters: applications

The Median Tectonic Zone (MTZ) of New Zealand is a generally north trending belt of Mesozoic subduction related I-type plutonic, volcanic, and sedimentary rocks in South Island and Stewart Island that separates Permian strata of the Eastern Province Brook Street Terrane from lower to mid Gondwana margin assemblages of the Western Province. High precision isotope dilution U/Pb ages of zircons from 30 rocks are reported. Pre-digestion leaching of zircon in hydrofluoric acid yielded significantly more concordant residues by removing common Pb and dissolving more soluble high-U domains that have been more affected by relatively recent Pb loss. The results show that MTZ magmatism ranges in age from at least Early Triassic to Early Cretaceous (247-131 Ma), with a pronounced gap in the Middle Jurassic. Triassic plutons tend to occur on the eastern side of the MTZ, and they intrude volcanic/sedimentary sequences of the MTZ in Nelson and eastern ...

39

Activation method for determination of Pb, La, Zr and Ti macrocomponents in lead-lanthanum zirconate-titanate materials on a neutron generator

Advances in the development of several electrooptic shutter devices utilizing the quadratic electrooptic effect of lead lanthanum zirconate titanate (PLZT) ceramic wafers are described. Aperture sizes utilized in these PLZT devices ranged from 25 ..mu..m to 0.25 m. Practical applications of the shutters discussed in this paper include eye protection in military and industrial applications, a goggle-type device with dual synchronously operated PLZT shutters for use in a stereoscopic three-dimensional TV display, an electrically controlled variable density filter for use with vidicon tubes, a large-aperture photographic shutter for image motion compensation cameras, and a page composer for use in a holographic memory system.

1975-08-01

40

Synthetic fuels at Sasol; Les carburants de synthese chez Sasol

Instrumental neutron activation analysis is used for simultaneously determination of macrocomponents in ferroelectric materials LLZT. Pb, Zr, Ti have been determined by "2"0"3Pb, "8"9Zr and "4"8Sc nuclides created by fast neutron (14.5 MeV) activation. Application of paraffine as neutron moderator and reflector allows to simultaneously determine lanthanum by "1"4"0La nuclide. It has been shown that zirconium, titanium and lanthanum can be determined with the accuracy of #+-#0.1 mas. % and lead - #+-#0.7 mas. %.

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41

Production and characterization of ultrafine WC powders

Sasol, a South-African company, has converted coal into synthetic fuels for 40 years; in order to increase by 6 pc its annual production (40 Mt coal are processed), Sasol has launched the Sky High project and intends to replace the ancient Sasol Synthol reactors by Advanced Synthol reactors using conventional fluidized beds instead of circulating fluidized beds. Coal is first gasified under high pressure and high temperature conditions (the Secunda site uses the Fischer-Tropsch conversion process) and is then processed in the reactor through a single phase process using an iron-base catalyst, leading to significant cost reductions.

1998-11-01

42

Problematic of atmospheric pollution in Lebanon: the better stake is apprehended, the best acts are taken

The conventional Calzination-Reduction-Carburization (CRC) process offers the potential to manufacture commercial WC powders with median SEM grain sizes below 0.5 pm (ultra fine grades). Strict process control and a high degree of automation have led to increased powder uniformity and high lot-to-lot reliability. The high potential and flexibility of the CRC process is shown by the development of tailor made WC powders with regard to subsequent alloy manufacturing. R and D powders have successfully been processed in full-scale units exhibiting SEM grain sizes of 0.15 - 0.20 pm. This paper discusses the powder characteristics of various ultra fine WC powder grades, stemming from the conventional CRC process. Analytical characterization include also field-emission SEM, bright field TEM, EDX analysis and XRD-line broadening. (author)

2001-05-01

43

Photosensitivity and imaging characteristics of ion-implanted PLZT ceramics

Lebanon has imported in 1996 5000 Kt of carburants causing about 80 Kt of SO_x; 40 Kt of NO_x; 3 Kt of dusts and 3.5 million tons of CO_2. The atmospheric pollution in Lebanon is due to three main sources: - Thermal central of electric production - Industries (cement) - Transportation sector The document describes in tables: the inventory of pollutants and pollutant emissions in 1993 and 2010; industrial and heating gas oil; liquified petroleum gas commercial propane; fuel oil for EDL; consumption of energy in 1996; sectorial distribution of pollutants PPM; emissions of CO_2 per tons per habitant in 1993; consumption in 1993 broken down by use and application. Finally, three projects concerning public transportation were presented

1999-06-02

44

Direct patterning of complex oxides by pulsed laser deposition through stencils

We reported in previous papers that both the near-uv and the visible photosensitivities of ferroelectric-phase PLZT (lead lanthanum zirconate titanate) ceramics are increased by as much as four orders of magnitude by ion implantation or a combination of thermal diffusion of Al and ion implantation. New results are presented here on high-energy (1 MeV) implants of Al and Ni and coimplants of Al + Ne and Ni + Ne, and these results are compared with earlier 500 keV implants of Al and Cr and coimplants of Al + Ne and Cr + Ne as surface modification techniques for increasing the visible photosensitivity of PLZT. The important role of grain size in determining optimum contrast and resolution of stored optical information is described in terms of new experimental results.

1985-08-12

45

Comparison of sodium zirconium phosphate and Synroc matrices for immobilization of high-level waste

The possibilities to grow isolated structures of complex oxides by pulsed laser deposition through stencils were investigated. A stencil consisting of a SiN membrane with apertures of several hundred nanometers embedded in a Si chip is placed in front of a heated substrate (up to 750 degrees Celsius). Deposition through these apertures results in resistless, direct patterning by local deposition of complex oxides like ferroelectric Lead Zirconate Titanate. The created isolated structures were analyzed by AFM imaging. Under-deposition, in this work called broadening, is inevitable during stencil deposition and is depending on deposition parameters, especially pressure. Different causes of broadening are mapped and discussed.

2007-04-01

46

Historical development of alloy 800

The aims of the present work were to investigate possible compatibility between sodium zirconium phosphate (NZP) and Synroc titanate phases, to prepare NZP-based waste forms by hot-pressing rather than sintering, and to investigate the incorporation in NZP of (a) Cs/Sr as simulated heat-generating nuclides; (b) simulated actinides; and (c) simulated Purex waste. The NZP samples were prepared by methods similar to those used for Synroc. The precursor NZP phase was formed from tetrabutyl zirconate Zr(OC{sub 4}H{sub 9}){sub 4}, sodium nitrate, and 85% orthophosphoric acid. Simulated waste nitrate solutions were then mixed with the liquid precursor. After stir drying of the precursor, calcination was carried out at 700{degree}C to remove nitrates and organics.

1996-12-31

47

A review of the gas species activity and control of pulsed plasma technology during the nitriding, carburizing and carbonitriding processes

Alloy 800 was developed in 1949 by The International Nickel Company, Inc. The basic composition, nominally 32wt.%Ni, 20.5wt.%Cr and 46wt.%Fe, was designed to provide a stable, fully austenitic structure and to impart high strength combined with resistance to oxidation, carburization and corrosion in a wide variety of aggressive industrial environments at elevated temperatures. In the short span of twenty-five years, alloy 800 has earned a unique position in the family of heat- and corrosion-resistant materials. Established uses include a wide range of applications in the industrial heating field, in the petro-chemical industry, in domestic appliances and in food processing equipment. The good performance of alloy 800 in these applications has led to its use as boiler tube material both in fossil-fired plants and in HTGR and PWR nuclear power systems. Recently, it was specified for a PHW CANDU reactor and it is now being considered as heat exchanger tube material ...

48

PbZrO sub 3 -doped (Ba,Sr)TiO sub 3 -based dielectrics for high-voltage capacitor applications

The control of gas activity and process technology has developed tremendously over the past two decades. While once considered to be primitive control systems using simple PID loops with thermocouples that were suspect and unable to perform repeatedly and consistently during the arduous process of plasma nitriding and processing, developments in recent years have elevated the control of the process into what might be considered one of the most controllable processes of the latter part of this century. The advent of plasma processing technology has improved control methods by observing and harnessing each of the various process parameters into many different combinations of control systems. Some of these control systems can control the complete function of the process, thus freeing the operator entirely for other duties, except that of load and unload, to the point where the operator is intimately involved with the process. Some of the control methods report from the process to a PLC ...

1995-12-31

49

Modification of surface texture by grinding and polishing lead zirconate titanate ceramics

This paper reports that high-dielectric ceramics with the composition (94.7% {minus} x) (Ba,Sr)TiO{sub 3} + PbZrO{sub 3} + 5Bi{sub 2}Ti{sub 3}O{sub 9} + 0.3MnO{sub 2}, where the ration (Ba)/(Sr) = 1.25 and x {le} 15 mol%, have been developed for high-voltage capacitors. The dielectric constant of the ceramics is in the range 1200 to 1900 at room temperature, and the room-temperature dielectric loss, tan{delta}, is less than 0.3%, except when 15 mol% PbZrO{sub 3} is added with sintering at 1180{degrees}C to 1240{degrees}C for 2 h. Ceramics with more than 8 mol% zirconate show the Y5S characteristic of capacitance, and those with less than 8 mol% additive exhibit the Z5S characteristic. The dielectric constant gradually increases with increment in the ac signal voltage at 60 Hz, but decreases beyond a threshold value that varies with zirconate content and sintering conditions. The variation of the dielectric constant at 2 kVrms/mm (with respect ...

1991-11-01

50

Modification of surface texture by grinding and polishing lead zirconate titanate ceramics

This paper reports that grinding and polishing affected the orientation of 90[degrees] domains at the surface of lead zirconate titanate (PZT) ceramics. This was quantified by using changes in the intensity ratio of the (002) and (200) X-ray reflections. Grinding unpoled PZT with 600-grit SiC paper gave X-ray intensity ratios similar to those of poled material. This implies that 90[degrees] domain realignments had occurred in the near surface region probed by the X-rays. Grinding poled samples with 600-grit SiC further increased the X-ray intensity ratio beyond that caused by poling, indicating that additional surface reorientation of 90[degrees] domains had occurred. The effects of diamond polishing depended on the size of the diamond particles. The use of 6-[mu]m diamond had no effect on the (002)/(200) intensity ratio of either poled or unpoled samples, while polishing with 15- or 45-[mu]m diamond significantly enhanced the 90[degrees] domain rotation. In ...

1992-08-01

51

Mineralogy and geochemistry of the No. 6 Coal (Pennsylvanian) in the Junger Coalfield, Ordos Basin, China

This paper reports that grinding and polishing affected the orientation of 90 degrees domains at the surface of lead zirconate titanate (PZT) ceramics. This was quantified by using changes in the intensity ratio of the (002) and (200) X-ray reflections. Grinding unpoled PZT with 600-grit SiC paper gave X-ray intensity ratios similar to those of poled material. This implies that 90 degrees domain realignments had occurred in the near surface region probed by the X-rays. Grinding poled samples with 600-grit SiC further increased the X-ray intensity ratio beyond that caused by poling, indicating that additional surface reorientation of 90 degrees domains had occurred. The effects of diamond polishing depended on the size of the diamond particles. The use of 6-#mu#m diamond had no effect on the (002)/(200) intensity ratio of either poled or unpoled samples, while polishing with 15- or 45-#mu#m diamond significantly enhanced the 90 degrees domain rotation. In unpoled ...

1992-01-01

52

Effects of gamma-irradiation on the TL characteristics of pre-annealed natural ZrSiO{sub 4}

This paper discusses the mineralogy and geochemistry of the No. 6 Coal (Pennsylvanian) in the Junger Coalfield, Ordos Basin, China. The results show that the vitrinite reflectance (0.58%) is lowest and the proportions of inertinite and liptinite (37.4% and 7.1%, respectively) in the No. 6 Coal of the Junger Coalfield are highest among all of the Late Paleozoic coals in the Ordos Basin. The No. 6 Coal may be divided vertically into four sections based on their mineral compositions and elemental concentrations. A high boehmite content (mean 6.1%) was identified in the No. 6 Coal. The minerals associated with the boehmite in the coal include goyazite, rutile, zircon, and Pb-bearing minerals (galena, clausthalite, and selenio-galena). The boehmite is derived from weathered and oxidized bauxite in the weathered crust of the underlying Benxi Formation (Pennsylvanian). A high Pb-bearing mineral content of samples ZG6-2 and ZG6-3 is likely of hydrothermal origin. The No. 6 ...

2006-04-03

53

Effects of gamma-irradiation on the TL characteristics of pre-annealed natural ZrSiO_4

By the use of thermoluminescence (TL) technique we have investigated the effects of gamma irradiation on the TL response of pulverised natural zircon (ZrSiO{sub 4}) crystals from the Jos Plateau area of Nigeria. Samples of the mineral that have been previously annealed were artificially irradiated to moderate gamma doses ranging from 0.7 to 4.9 Gy using {sup 60}Co gamma-source of the CERD. The natural TL glow curve of the sample showed a broad peak around 250 deg. C, the peak was however, found to be completely erased following heat treatment for 2 h at 400 deg. C. The TL glow curves of the artificially irradiated samples showed two overlapping glow peaks at about 112 deg. C (peak I) and at 156 deg. C (peak II) within the dose range utilised. We note that the natural TL peak appears to be different from the two observed in the artificially irradiated sample. The TL response with dose was investigated for the two glow peaks found in the artificially irradiated ...

2005-10-15

54

Chemical solution deposition of ferroelectric lead lanthanum zirconate titanate films on base-metal foils.

By the use of thermoluminescence (TL) technique we have investigated the effects of gamma irradiation on the TL response of pulverised natural zircon (ZrSiO_4) crystals from the Jos Plateau area of Nigeria. Samples of the mineral that have been previously annealed were artificially irradiated to moderate gamma doses ranging from 0.7 to 4.9 Gy using "6"0Co gamma-source of the CERD. The natural TL glow curve of the sample showed a broad peak around 250 deg. C, the peak was however, found to be completely erased following heat treatment for 2 h at 400 deg. C. The TL glow curves of the artificially irradiated samples showed two overlapping glow peaks at about 112 deg. C (peak I) and at 156 deg. C (peak II) within the dose range utilised. We note that the natural TL peak appears to be different from the two observed in the artificially irradiated sample. The TL response with dose was investigated for the two glow peaks found in the artificially irradiated sample and in ...

2005-10-01

55

Preparation of ZrO_2/O'-sialon composites using dissociation of zircon

Development of electronic devices with better performance and smaller size requires the passive components to be embedded within a printed wire board (PWB). The 'film-on-foil' approach is the most viable method for embedding these components within a PWB. We have deposited high-permittivity ferroelectric lead lanthanum zirconate titanate (Pb{sub 0.92}La{sub 0.08}Zr{sub 0.52}Ti{sub 0.48}O{sub x}, PLZT 8/52/48) films on base metal foils by chemical solution deposition. These prefabricated capacitor sheets can be embedded into PWBs for power electronic applications. To eliminate the parasitic effect caused by the formation of a low-permittivity interfacial oxide, a conductive buffer layer of lanthanum nickel oxide (LNO) was applied by chemical solution deposition on nickel foil before the deposition of PLZT. With a {approx} 0.7-{micro}m-thick ferroelectric PLZT film grown on LNO-buffered nickel foil, we measured capacitance densities of 1.5 ...

2009-01-01

56

Observation of high permittivity in Ho substituted BaZr_0_._1Ti_0_._9O_3 ceramics

ZrO_2/O'-sialon composites were obtained via reaction sintering of ZrSiO_4 and Si_3N_4 powders at about 1700 deg C. Y_2O_3 was effective in both stabilizing of zirconia and densifying the composites. However, it is not easy to select an optimum value of the single additive to balance these two requirements simultaneously. With low Y_2O_3 addition, some tetragonal zirconia grains in the sintered samples are transformable during mechanical grinding but the full densification of the material is then sacrificed. On the other hand, addition more Y_2O_3 to achieve complete densification results in the zirconia being stabilized into undesirable t' or cubic forms. Therefore no improved toughening effects have been achieved in the composites. Heat-treatment of the materials at 1400 deg C. results in the diffusion of yttria from the grain boundary phase to zirconia and the formation of the O'-cubic zirconia composite may still provide a useful refractory material. 11 refs., 5 tabs., 2 figs.

57

High lithium ion conductive Li7La3Zr2O12 by inclusion of both Al and Si

The authors observed an extremely high permittivity (#approx#35 000 at T_C) in barium zirconate titanate (BaZr_0_._1Ti_0_._9O_3) ceramics with holmium substitution (1-5 mol %) in Ba site. Careful microstructural investigation and energy dispersive spectroscopy analysis of the 1-2 mol % of Ho substituted ceramics showed the enrichment of a Ho-phase along the grain boundaries with a composition close to the Ho_2Ti_2O_7 pyrochlore. The formation of Ho rich phase resulted in the Maxwell-Wagner polarization mechanism, which leads to this unusually high permittivity. Ceramics with 3 mol % or higher Ho content showed lesser permittivity values compared to 1-2 mol %, probably due to the increase in pyrochlore phase. These high dielectric constant ceramics are useful in nanoscale devices.

2007-07-09

58

British Library Electronic Table of Contents (United Kingdom)

High lithium-ion (Li^+) conductive garnet-structured lanthanum lithium zirconate (LLZ) solid electrolyte is prepared by incorporation of appropriate amounts of silicon (Si) and aluminum (Al). The resultant pelletized LLZ obtains total Li^+ conductivity of 6.8x10^-^4Scm^-^1 at 298K. This improved conductivity is nearly identical with the bulk Li^+ conductivity of the LLZ reported earlier, suggesting that the grain boundary resistance is effectively reduced by the incorporation of Si and Al. Microanalyses by transmission electron microscopy coupled with energy-dispersive X-ray microanalysis and electron energy-loss spectroscopy revealed the presence of amorphous Li-Al-Si-O with nano crystalline LiAlSiO4 at grain boundaries. Fast lithium-ion transport around the amorphous Li-Al-Si-O/LiAlSiO4 ...

2011-01-01

59

BNFL Report Glass Formers Characterization

Sol-gel synthesis of high-quality SrRuO{sub 3} thin film electrodes suppressing the formation of detrimental RuO{sub 2} and the dielectric properties of integrated lead lanthanum zirconate titanate films.

The objective of this task was to obtain powder property data on candidate glass former materials, sufficient to guide conceptual design and estimate the cost of glass former handling facilities as requested under Part B1 of BNFL Technical and Development Support. Twenty-nine glass forming materials were selected and obtained from vendors for the characterization of their physical properties, durability in caustic solution, and powder flow characteristics. A glass former was selected based on the characterization for each of the ten oxide classes required for Envelope A, B, and C mixtures. Three blends (A, B, and C) were prepared based on formulations provided by Vitreous State Laboratory and evaluated with the same methods employed for the glass formers. The properties obtained are presented in a series of attached Tables. It was determined that five of the ten glass formers, (kyanite, iron oxide, titania, zircon, and zinc oxide) have the potential to cause some ...

2000-07-27

60

High-pressure gas quenching in cold chambers for increased cooling capacity

A facile solution chemistry is demonstrated to fabricate high-quality polycrystalline strontium ruthenium oxide (SrRuO{sub 3}) thin film electrodes on silicon substrates suppressing the formation of undesired ruthenium oxide (RuO{sub 2}) for the deposition of dielectric and ferroelectric materials like lead lanthanum zirconate titanate (PLZT). The robust, highly crystalline SrRuO{sub 3} film fabrication process does not favor the formation of RuO{sub 2} because of molecular level modification of the precursors possessing analogous melting points, yielding homogeneous films. This chemistry is further understood and complemented by kinetic and thermodynamic analysis of the DTA data under nonisothermal conditions, with which the activation energies to form RuO{sub 2} and SrRuO{sub 3} were calculated to be 156 {+-} 17 and 96 {+-} 10 kJ/mol, respectively. The room-temperature resistivity of the SrRuO{sub 3} film was measured to be 850 {+-} 50 {mu}{Omega} cm on silicon ...

2011-01-01

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61

Effects of plastic waste injection on the cupola furnace and blast furnace process; Auswirkungen des Einblasens von Kunststoffabfaellen auf den Kupolofen- und Hochofenprozess

Gas quenching for the hardening of steel parts is a lower-pollution alternative to quenching in quenchants such as oil or salt. As the surfaces of the cooled parts remain clean after gas quenching, there is no need to wash them after heat treatment, which reduces the consumption of oils and detergents. The fire risk and ventilation requirements of oil quenching are eliminated. In addition, some trials have shown that gas quenching has a positive effect on distortion, representing a saving in finishing work and thus a reduction in costs. Today, gas quenching is used almost solely in vacuum furnaces. Quenching is normally performed in the same chamber as heating, which means that besides quenching the batch, the quenching system must also remove heat from the heating elements and insulation of the furnace. Previous trials performed by IVF have shown that gas quenching with helium of ball bearing and carburizing steels (and other steels) in sizes up to 25 mm at ...

1996-12-31

62

Geology of 1. 7 GA ( ) Baldwin gneiss in the Baldwin Lake type area, San Bernardino Mountains, southern California

On account of a raised appearing of plastic waste and shreddered light fraction (SLF) from old car utilization as well as legal handicaps experiments were carried out at the Institute of Ferrous Metallurgy (RWTH Aachen) on a laboratory rig to inject DSD (Duales System Deutschland)-plastic waste and SLF with the destination of a subsequent raw material utilization in the blast furnace and cupola furnace. The experiments on the laboratory rig with DSD plastics could verify that by injection of specific coal/plastic mixtures into the blast furnace the injection rate could be raised by an improvement in the conversion degree and therefore the amount of the inserted reducing agent can be lowered. The injection of SLF without reduction of the inert materials and of the contents on alloying elements and/or tramp elements by extensive preparation has no advantages according to the experiments for the blast furnace process. Pilot experiments on the cupola furnace showed that, assuming a certain ...

1996-01-01

63