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Sample records for sinter forging bi-2223

  1. Critical current densities in Bi-2223 sinter forgings.

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, U.; Fisher, B. L.; Goretta, K. C.; Harris, N. C.; Murayama, N.

    1999-07-23

    (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223) bars, prepared by sinter forging, exhibited good phase purity and strong textures with the c axes of the Bi-2223 grains parallel to the forging direction. The initial zero-field critical current density (J{sub c}) of the bars was 10{sup 3} A/cm{sup 2}, but because the forged bars were uncoated, this value decreased with repeated thermal cycling. J{sub c} as a function of applied magnetic field magnitude and direction roughly followed the dependencies exhibited by Ag-sheathed Bi-2223 tapes, but the forged bars were more strongly dependent on field strength and less strongly dependent on field angle.

  2. Fabrication of Bi2223 bulks with high critical current properties sintered in Ag tubes

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Yasuaki, E-mail: ytakeda@g.ecc.u-tokyo.ac.jp [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Shimoyama, Jun-ichi; Motoki, Takanori [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258 (Japan); Kishio, Kohji [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nakashima, Takayoshi; Kagiyama, Tomohiro; Kobayashi, Shin-ichi; Hayashi, Kazuhiko [Sumitomo Electric Industries, Ltd. 1-1-3 Shimaya, Konohana-ku, Osaka 554-0024 (Japan)

    2017-03-15

    Highlights: • Fabrication conditions of Bi2223 bulks was reconsidered in terms of high J{sub c}. • Pressure of uniaxial pressing and heat treatment conditions were investigated. • The best sample showed higher J{sub c} than that of practically used Bi2223 bulks. - Abstract: Randomly grain oriented Bi2223 sintered bulks are one of the representative superconducting materials having weak-link problem due to very short coherence length particularly along the c-axis, resulting in poor intergrain J{sub c} properties. In our previous studies, sintering and/or post-annealing under moderately reducing atmospheres were found to be effective for improving grain coupling in Bi2223 sintered bulks. Further optimizations of the synthesis process for Bi2223 sintered bulks were attempted in the present study to enhance their intergrain J{sub c}. Effects of applied pressure of uniaxial pressing and sintering conditions on microstructure and superconducting properties have been systematically investigated. The best sample showed intergrain J{sub c} of 2.0 kA cm{sup −2} at 77 K and 8.2 kA cm{sup −2} at 20 K, while its relative density was low ∼65%. These values are quite high as for a randomly oriented sintered bulk of cuprate superconductors.

  3. Effect of the variation-temperature-sintering on microstructure and superconducting properties of Bi-2223/Ag tapes in high magnetic fields

    International Nuclear Information System (INIS)

    Lu, X.Y.; Watanabe, K.; Yi, D.; Chen, H.; Nagata, A.

    2011-01-01

    The microstructure and superconducting properties of Bi-2223/Ag tapes fabricated in the variation-temperature-sintering process during high magnetic fields were investigated. The flat tapes 0.6 mm in thickness and 3 mm in width set on the an isolite holder were sintered in following conditions for 120 h in 10 T magnetic fields in air: (1) isothermal-temperature-sintering at 835 deg. C, (2) variation-temperature-sintering from 840 to 835 deg. C, (3) variation-temperature-sintering from 845 to 835 deg. C, (4) variation-temperature-sintering from 850 to 835 deg. C, (5) variation-temperature- sintering from 835 to 840 deg. C. The results show that the tapes variation-temperature-sintered from high temperature to low temperature show stronger c-axis alignment of the Bi-2223 phase and higher J c value than that isothermal-temperature-sintered and variation-temperature-sintered from low temperature to high temperature. However, the starting temperature (above 850 deg. C) of the variation-temperature-sintering from high temperature to low temperature is too high, the proportion of Bi-2223 phase decreases largely. The tape variation-temperature-sintered from 845 to 835 deg. C in a 10 T magnetic fields shows a strong c-axis alignment of the Bi-2223 phase, a high proportion of Bi-2223 phase, and the highest J c value.

  4. Sintering and densification; new techniques: sinter forging

    International Nuclear Information System (INIS)

    Winnubst, A.J.A.

    1998-01-01

    In this chapter pressure assisted sintering methods will be described. Attention will mainly be paid to sinter forging as a die-wall free uniaxial pressure sintering technique, where large creep strains are possible. Sinter forging is an effective tool to reduce sintering temperature and time and to obtain a nearly theoretically dense ceramic. In this way grain size in tetragonal zirconia ceramics can be reduced down to 100 nm. Another important phenomenon is the reduction of the number density and size of cracks and flaws resulting in higher strength and improved reliability, which is of utmost importance for engineering ceramics. The creep deformation during sinter forging causes a rearrangement of the grains resulting in a reduction of interatomic spaces between grains, while grain boundary (glassy) phases can be removed. The toughness and in some cases the wear resistance is enhanced after sinter forging as a result of the grain-boundary-morphology improvement. (orig.)

  5. Processing of bulk Bi-2223 high-temperature superconductor

    Directory of Open Access Journals (Sweden)

    Alexander Polasek

    2005-12-01

    Full Text Available The Bi2Sr2Ca2Cu3 O10+x (Bi-2223 is one of the main high temperature superconductors for applications. One of these applications is the Superconductor Fault Current Limiter (SCFCL, which is a very promising high temperature superconducting device. SCFCL's can be improved by using bulk superconductors with high critical currents, which requires a sufficiently dense and textured material. In the present work, a process for improving the microstructure of Bi-2223 bulk samples is investigated. Pressed precursor blocks are processed by sintering with a further partial melting step, in order to enhance the Bi-2223 grain texture and to healing cracks induced by pressing. In order to improve the microstructure, the precursor is mixed with silver powder before pressing. Samples with and without silver powder have been studied, with the aim of investigating the influence of silver on the microstructure evolution. The phase contents and the microstructure obtained have been analyzed through XRD and SEM/EDS. The electromagnetic characterization has been performed by Magnetic Susceptibility Analysis. We present and discuss the process and the properties of the superconducting blocks. High fractions of textured Bi-2223 grains have been obtained.

  6. (Bi, Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} superconductor and method of making same utilizing sinter-forging

    Science.gov (United States)

    Chen, N.; Goretta, K.C.; Lanagan, M.T.

    1998-10-13

    A (BiPb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x}(Bi223) superconductor with high J{sub c}, phase purity, density and mechanical strength is formed from Bi2223 powder which is synthesized from a mixture of Bi{sub 2}O{sub 3}, PbO, SrCO{sub 3}, CaCo{sub 3} and CuO. The mixture is milled, then dried and calcined to synthesize the Bi2223 powder with the desired phase purity. The calcination is performed by heating the dried mixture for 50 hours at 840 C. The partially synthesized powder is then milled for 1--4 hours before calcining further for another 50 hours at 855 C to complete the synthesis. After calcination, the Bi2223 powder is cold pressed to a predetermined density and sinter forged under controlled temperature and time to form a Bi2223 superconductor with the desired superconducting properties. 5 figs.

  7. Electro sinter forging of titanium disks

    DEFF Research Database (Denmark)

    Cannella, Emanuele; Nielsen, Chris Valentin; Bay, Niels Oluf

    Electro sinter forging (ESF) is a new sintering process based on the principle of electrical Joule heating. In the present work, middle frequency direct current (MFDC) was flowing through the powder compact, which was under mechanical pressure. The main parameters are the high electrical current,...

  8. Effect of Ag in structural, electrical and magnetic properties of Ag-sheated Bi-2223 wires

    Directory of Open Access Journals (Sweden)

    D Sohrabi

    2009-08-01

    Full Text Available  In this study, the superconducting properties of Bi-2223/Ag wires, made by the PIT method have been studied. Powder samples were prepared using conventional solid state reaction method. After calcination, samples with different Ag percent (0, 5, 10, 15, 20, and 25 prepared and sintered at 830 °C. It was shown that Ag addition has not only affected the formation of the desired Bi-2223 phase and the microstructure of these wires, but also influenced on the critical current density (JC and critical temperature.

  9. Higher critical current density achieved in Bi-2223 High-Tc superconductors

    Directory of Open Access Journals (Sweden)

    M.S. Shalaby

    2016-07-01

    Full Text Available Bi2Sr2Ca2Cu3Ox (Bi-2223 were prepared using a solid state reaction method at different sintering times and temperatures. Structural phase identifications have been done using X-Ray analysis and refinement by Reitveld method which proves the coexistence of Bi-2223 and Bi-2212 phases. The critical transition temperature Tc and critical current density Jc values were measured using superconducting quantum interference device magnetometer (SQUID and by the magneto-optics technique. A remarkable rapid decrease to the diamagnetic signal in the magnetization versus temperature M(T at 110 K and Jc around 1.2 × 107 A/m2 at 5 K are confirmed for the Bi-2223 compound.

  10. Gd-substituted Bi-2223 superconductor

    Indian Academy of Sciences (India)

    The effects of gadolinium doping at calcium site on the normal and super- conducting properties of Bi-2223 system were ... quantities of the metal oxides and the carbonates were taken and thoroughly mixed. The calcination of the mixture after .... Therefore, Gd has higher solubility in (BiPb)-2223 as compared to Pr, and is, ...

  11. Magnetization studies of Bi-2223 tapes

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, K.H.; Andrikidis, C. [CSIRO, Sydney, NSW (Australia). Division of Applied Physics; Liu, H.K.; Dou, S.X. [University of Wollongong, NSW (Australia). Centre for Superconducting and Electronic Materials

    1996-12-31

    Full text: Superconducting Bi-2223 silver sheathed tapes show a critical current density large enough for power transmission line applications where the magnetic fields involved are small. Unfortunately, the performance of these tapes at 77 K in large fields is quite poor and a better understanding of magnetization data might help to elucidate the reasons for the limitation of the tape`s current carrying capacity. We have investigated by means of magnetic moment measurements on monofilamentary Bi-2223 tapes, using a Quantum Design SQUID magnetometer, the correlation between intergranular critical current density J{sub c}{sup J} which is flowing over the entire tape, and the intragranular critical current density J{sub c}{sup G} which is flowing inside grains. The experimental data reveal that J{sub c}{sup G} depends strongly on the magnetic history of grains and the value of J{sub c}{sup G}. The anomalous peak seen in magnetization loops of tapes correlates well with the peak seen in the critical current density measured electrically in a decreasing magnetic field. The position of the anomalous peak does not shift further to higher fields when the applied field exceeds the field of full grain penetration. By separating the silver cladding from the superconductor we found that, opposite to common believe, the current does not flow mainly near the superconductor-silver interface but is more homogeneously distributed throughout the filament

  12. Synthesis of Pb-doped Bi-2223 from Pb-doped Bi-2212, Ca2CuO3, and CuO Above the Glass Transition Temperature of Bi-2212

    Directory of Open Access Journals (Sweden)

    Marvin U. Herrera

    2002-12-01

    Full Text Available Synthesis of Pb-doped Bi-2223 from Pb-doped Bi-2212 (Pb=0.3, Ca2CuO3, and CuO was done by sintering at the glass-phase temperature of Pb-doped Bi-2212. The sample sintered at 850°C possesses nearly 100% Pb-doped Bi-2223, as revealed from the XRD pattern and magnetic susceptibility data. The presence of holes, terrace-like features, and magma-like flow features in the SE< micrographs of the sample strongly support a glass-state Pb-doped Bi-2223 formation.

  13. Tool design and materials for electro sinter forging (ESF)

    DEFF Research Database (Denmark)

    Cannella, Emanuele; Nielsen, Chris Valentin

    A near net-shape forming process represents a suitable solution to obtain the final product by avoiding secondary machining processes. In this field, electro sinter forging is capable of accomplishing the advantages of sintering in a reduced amount of time. Classified as a high field mode (HFM...

  14. Transmission electron microscopy investigation of Bi-2223/Ag tapes

    DEFF Research Database (Denmark)

    Andersen, L.G.; Bals, S.; Tendeloo, G. Van

    2001-01-01

    The microstructure of (Bi,Pb)(2)Sr2Ca2CuOx (Bi-2223) tapes has been investigated by means of transmission electron microscopy (TEM) and high-resolution TEM. The emphasis has been placed on: (1) an examination of the grain morphology and size, (2) grain and colony boundary angles, which are formed...

  15. Role of vanadium in Bi-2223 ceramics

    Indian Academy of Sciences (India)

    of substituting element more than just a sintering agent as reflected in the more rapid decrease in Мc at Cu-site and further in the ... with other elements [2] are being attempted for the further improvements in these materials especially if we ..... Other specimen (not shown) have mixed grain growth of needle shaped as well as ...

  16. Large Scale Assembly and Characterization of BI-2223 HTS Conductors

    CERN Document Server

    Ballarino, Amalia; Mathot, Serge; Taylor, T; Brambilla, R

    2007-01-01

    The powering of the LHC machine requires more than 1000 High Temperature Superconducting (HTS) current leads. These leads contain, at their cold end, HTS conductors made of stacks of Bi-2223 tape with gold-doped silver matrix. CERN specified and purchased 31 km of this material, which was delivered on spools in unit lengths of 100 to 300 m. On reception the tape was inspected, cut into short length and vacuum soldered into stacks. All stacks were characterized in liquid nitrogen using a measuring procedure and set-up specifically developed for this purpose. Contact resistance values and critical currents at different electric field criteria were measured, from which the n-values have been extrapolated from the experimental V-I characteristics. This paper reports on the assembly and electrical characterization (up to 800 A) of more than ten thousand Bi-2223 stacks. Three types of stack were made from tape from two manufacturers. The assembly and soldering procedures and the set-up for the series electrical cha...

  17. Optimization of precursor powders for manufacturing Bi-2223/Ag tapes

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, C H [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang (China); Yoo, J M [Materials Engineering Department, Korea Institute of Machinery and Materials, 66 Sangnam-Dong, Changwon (Korea, Republic of); Ko, J W [Materials Engineering Department, Korea Institute of Machinery and Materials, 66 Sangnam-Dong, Changwon (Korea, Republic of); Chung, H S [Department of Molecular Science and Technology, Ajou University (Korea, Republic of); Qiao, G W [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang (China)

    2003-01-01

    The phase assemblage and particle sizes of precursor powders have been optimized in a sequence for fabricating Ag/BSCCO-2223 composite tapes. Firstly, an optimal calcination temperature was determined based on the experimental results. Then, the precursors calcined at the optimal temperature were ball-milled for different dwell times to obtain varied particle sizes. The effects of both the phase assemblages and particle sizes of the precursor powder on the phase formation, microstructure and transport J{sub c} of Bi-2223/Ag tapes have been investigated. The results show that the precursor phase assemblage has a large impact on the reaction routes, microstructure, and J{sub c} property. Meanwhile, a fine powder is beneficial for the grain growth, alignment, and J{sub c} enhancement in fully reacted tapes. The best J{sub c} was achieved in the tape made from the powder after optimizing the phase assemblage and particle size.

  18. Optimization of multilayered Bi-2223/Ag-Au conductors for current lead applications

    International Nuclear Information System (INIS)

    Martini, L.; Barberis, F.; Berti, R.; Bigoni, L.; Curcio, F.; Volpini, G.

    1999-01-01

    Multilayered Bi-2223 composite conductors fabricated by means of the Accordion folding method appear to be suitable for applications as current leads (CL). In this work, the authors report on the results of electrical characterization of silver-gold alloy sheathed Bi-2223 conductors up to 400 mm long, having a DC overall critical current density J ceng exceeding 3000 A/cm 2 at 77 K. The I c evolution from the first to the third thermal treatment as well as the uniformity along the specimen length has been monitored. Lastly, calculations of the magnetic field profile across stacked multilayered Bi-2223 conductors are reported and discussed

  19. Ba2ErNbO6: A new perovskite ceramic substrate for Bi (2223 ...

    Indian Academy of Sciences (India)

    Barium erbium niobate (Ba2ErNbO6) has been developed as a new substrate for (Bi,Pb)2Sr2Ca2Cu3O [Bi(2223)] superconductor film. Ba2ErNbO6 (BENO) has a cubic perovskite structure with lattice constant, = 8.318 Å. The Bi(2223) superconductor does not show any detectable chemical reaction with BENO even ...

  20. Losses of new type HTS wires with transposed Bi-2223 filaments; Fuiramento ten'igata Bi-2223 tashin senzai no sonshitsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Watabe, K.; Yamashita, K.; Sumiyoshi, F. [Kagoshima Univ., Kagoshima (Japan); Hayashi, H.; Irie, F. [Kyushu Electric Power Co. Inc., Fukuoka (Japan)

    2000-05-29

    In Bi-2223 multifilamentary wire, large hysteresis loss occurs by 'self-magnetic field effect' where transport current flows on the surface. To prevent from this, uniformity of transport current distribution by filament transposition is effective. Round wire with two layers of helical coil around Ag core material by four Bi-2223 multifilamentary wires was fabricated as trial. Uniform condition of current distribution was explored and twist angle was found to be an important parameter. Hysteresis loss of wound wire in a reverse direction was reduced by 1/3 compared with one of wound wire in a same direction and known wire. (NEDO)

  1. Surface morphology and physical properties of partially melt textured Mn doped Bi-2223

    Directory of Open Access Journals (Sweden)

    Indu Verma

    2011-09-01

    Full Text Available The samples of Bi2Sr2Ca2Cu3-xMnxO10+δ (x = 0.0 to 0.30 were prepared by the standard solid-state reaction method. The phase identification characteristics of synthesized (HTSC materials were explored through powder X-ray diffractometer reveals that all the samples crystallize in orthorhombic structure with lattice parameters a = 5.4053 Å, b = 5.4110 Å and c = 37.0642 Å up to Mn concentration of x = 0.30. The critical temperature (Tc measured by standard four probe method has been found to depress from 108 K to 70 K as Mn content (x increases from 0.00 to 0.30. The effects of sintering temperature on the surface morphology of Bi2Sr2Ca2Cu3-xMnxO10+δ have also been investigated. The surface morphology investigated through scanning electron microscope and atomic force microscopy (SEM & AFM results that voids are decreasing but grains size increases as the Mn concentration increases besides, nanosphere like structures on the surface of the Mn doped Bi2Sr2Ca2Cu3-xMnxO10+δ (Bi-2223 samples.

  2. AC loss characteristics of Bi-2223 HTS tapes under bending

    International Nuclear Information System (INIS)

    Kim, Hae-Joon; Kim, J.H.; Cho, J.W.; Sim, K.D.; Kim, S.; Oh, S.S.; Kwag, D.S.; Kim, H.J.; Bae, J.H.; Seong, K.C.

    2006-01-01

    Superconductor is developed for applications in high-power devices such as power-transmission cables, transformers, motors and generators. In such applications, HTS tapes are subjected to various kinds of stress or strain. AC loss is also important consideration for many large-scale superconducting devices. In the fabrication of the devices, the critical current (I c ) of the high temperature superconductor degrades due to many reasons including the tension applied by bending and thermal contraction. These mechanical loads reduce the I c of superconducting wire and the I c degradation affects the AC loss of the wire. The I c degradation and AC loss of Bi-2223 HTS tape were measured under tension and bending conditions at 77 K and self-field. Moreover, the frequency characteristics of AC loss was measured at the 30-480 Hz. As a result, self-field penetrates the deeper into the conductor at the lower frequency, which means higher self-field losses per cycle

  3. Self-field AC losses in Bi-2223 superconducting tapes

    International Nuclear Information System (INIS)

    Mueller, K. H.; Leslie, K.E.

    1996-01-01

    Full text: The self-field AC loss in Bi-2223 silver sheathed tapes for AC currents of up to 100 A was measured at 77 K and frequencies of 60 Hz and 600 Hz using a lock-in amplifier. The frequency dependence indicated a purely hysteretic loss which can be well described in terms of the critical state model for a flat superconducting strip. The only parameter needed to predict the self-field AC loss is the critical current of the critical state. Because the loss voltage is extremely small compared with the inductive voltage, a very high accuracy of the lock-in amplifier phase setting is required. Unlike in loss measurements on cylindrical superconducting samples, in the case of the tape the measuring circuit leads have to be brought out from the surface forming a loop where the changing magnetic field induces an additional voltage. Only if the loop formed by the leads at the voltage tabs is large enough will the apparent power dissipation approach the real AC loss associated with the length of the sample probed

  4. Development and fabrication of a Bi-2223 racetrack coil for generator applications

    International Nuclear Information System (INIS)

    Herd, K.G.; Salasoo, L.; Laskaris, E.T.; Ranze, R.A.; King, C.G.

    1996-01-01

    The development and fabrication of a layer-wound, epoxy-impregnated Bi-2223 high-temperature superconducting (HTS) racetrack coil which generates 40,000 ampere-turns of magnetomotive force (MMF) at 25 K is described. The coil was wound using Ag-sheathed Bi-2223 tape conductor laminated with copper foils for strength enhancement and insulated using a paper-wrap method. After epoxy impregnation, the coil was tested over a range of 16--25 K in a vacuum dewar using a closed-cycle helium refrigeration system. Descriptions of the tape lamination and insulation processing, the coil winding and impregnation, and the experimental test setup are given

  5. Microstructural dynamics of Bi-2223/Ag tapes annealed in 8% O2

    DEFF Research Database (Denmark)

    Andersen, L.G.; Poulsen, H.F.; Abrahamsen, A.B.

    2002-01-01

    The microstructural dynamics of Bi-2223 tapes are investigated in situ during annealing in 8% O-2 by means of 100 keV x-ray diffraction. A green mono- and a green multi-filamentary tape are annealed at 829.5 degreesC. During ramp-up (Ca,Sr)(2)PbO4 decomposes above 750 degreesC, resulting...... degreesC on quenched tapes shows a reaction over 3 weeks, whereby randomly oriented 3222 grains are formed and Bi-2223 is depleted of Pb. Simultaneously, the critical current decreases by a factor of 2....

  6. Improvement of mechanical strength of sintered Mo alloyed steel by optimization of sintering and cold-forging processes with densification

    Science.gov (United States)

    Kamakoshi, Y.; Shohji, I.; Inoue, Y.; Fukuda, S.

    2017-10-01

    Powder metallurgy (P/M) materials have been expected to be spread in automotive industry. Generally, since sintered materials using P/M ones contain many pores and voids, mechanical properties of them are inferior to those of conventional wrought materials. To improve mechanical properties of the sintered materials, densification is effective. The aim of this study is to improve mechanical strength of sintered Mo-alloyed steel by optimizing conditions in sintering and cold-forging processes. Mo-alloyed steel powder was compacted. Then, pre-sintering (PS) using a vacuum sintering furnace was conducted. Subsequently, coldforging (CF) by a backward extrusion method was conducted to the pre-sintered specimen. Moreover, the cold-forged specimen was heat treated by carburizing, tempering and quenching (CQT). Afterwards, mechanical properties were investigated. As a result, it was found that the density of the PS specimen is required to be more than 7.4 Mg/m3 to strengthen the specimen by heat treatment after CF. Furthermore, density and the microstructure of the PS specimen are most important factors to make the high density and strength material by CF. At the CF load of 1200 kN, the maximum density ratio reached approximately 99% by the use of the PS specimen with proper density and microstructure. At the CF load of 900 kN, although density ratio was high like more than 97.8%, transverse rupture strength decreased sharply. Since densification caused high shear stress and stress concentration in the surface layer, microcracks occurred by the damages of inter-particle sintered connection of the surface layer. On the contrary, in case of the CF load of 1200 kN, ultra-densification of the surface layer occurred by a sufficient plastic flow. Such sufficient compressed specimens regenerated the sintered connections by high temperature heat treatment and thus the high strength densified material was obtained. These processes can be applicable to near net shape manufacturing

  7. Optimum working temperature of power devices based on Bi-2223 superconductors

    International Nuclear Information System (INIS)

    Oomen, M.P.; Haken, B. ten; Leghissa, M.; Rieger, J.

    2000-01-01

    Transformers, motors and magnets based on Bi-2223 tapes have an optimum working temperature where the um of investment and exploitation costs has a minimum. The investment cost is lower at temperatures below 77 K due to the higher critical current of the superconductor. The exploitation cost is mainly determined by the ac loss, which is dominated by the magnetization loss. The magnetization loss of a Bi-2223 tape at 48 Hz is measured for various temperatures between 65 and 77 K. The temperature dependence of the magnetization loss is fully explained by the change in critical current and agrees with the critical-state model. At high magnetic-field amplitudes the magnetization loss normalized with the critical current is independent of the temperature. Nevertheless, at lower temperatures the exploitation cost is higher due to the higher cooling penalty factor. A relation for the optimum temperature is developed, based on realistic expressions for the cooling penalty factor and the critical current as a function of the temperature. The influence of the other relevant parameters is summarized into a single dimensionless number. It is concluded that the optimum temperature of a power device based on Bi-2223 tapes is in the range 65-75 K. (author)

  8. Acid-base equilibrium. A thermodynamic study of formation and stability of the Bi-2223 phase

    International Nuclear Information System (INIS)

    Xi, Z.; Zhou, L.

    1993-01-01

    A general acid-base equilibrium theory was proposed to explain the formation and stability of the Bi-2223 phase based on the Lewis acid base theory and principle of metallurgical physical chemistry. The acid-base nature of oxide was defined according to the electrostatic force between cation and oxygen anion. A series of experimental facts were systematically explained based on the theory: substitution of Bi for Ca in the Pb-free 2223 phase, and the effect of substitution of the high-valent cation for Bi 3+ ; oxygen-pressure atmosphere, and the heat-schocking technique on the formation and stability of the 2223 phase. 14 refs., 2 tabs

  9. The Effect of Temperature Dependence of AC Losses in a Bi-2223/Ag Insert of an 8-T Superconducting Magnet

    DEFF Research Database (Denmark)

    Wang, Lei; Wang, Qiuliang; Wang, Hui

    2016-01-01

    A conduction-cooled split-gap superconducting magnet system with a center field of 8 T has been designed and fabricated in the Institute of Electrical Engineering, Chinese Academy of Sciences. The system consists of two Bi-2223/Ag coils and six NbTi coils. Due to a large aspect ratio of the high......-temperature superconducting tape, there will be large ac losses when the magnet is ramped up and down. An accurate estimation of the total ac losses in the high-temperature superconducting coils is essential for the cryogenic system design. In the Bi-2223/Ag coils, the total ac losses mainly originate from two parts: One...... is transport loss caused by the variation of transport current with respect to time, and the other is magnetization loss due to alternating external magnetic field. In this paper, the effect of temperature variation on ac losses generated in the Bi-2223/Ag coils is studied. The magnetic field and temperature...

  10. Bending strain study of Bi-2223/Ag tapes using Hall sensor magnetometry

    International Nuclear Information System (INIS)

    Lahtinen, M.; Paasi, J.; Sarkaniemi, J.; Han, Z.; Freltoft, T.

    1996-01-01

    The influence of room temperature bending on critical current (I c ) of Bi-2223/Ag tapes is studied by Hall sensor magnetometry, four-point method and scanning electron microscopy. Hall sensor magnetometry allows one to assess tape homogeneity and the amount of mechanical damage caused by bending. The microstructure of the Bi-2223 ceramic is found to strongly affect the tape behavior under bending strain. In a tape with moderate I c = 6.1 A at 77 K and a porous ceramic core, crack propagation took place normal to the Ag-ceramic interface, whereas in tapes with dense core, I c above 10 A at 77 K, cracks propagated in the tape plane. In monofilamentary tapes core homogeneity correlated with good bending strain performance. In multifilamentary tapes crack propagation between filaments was prohibited by the Ag matrix, thus leading to enhanced strain tolerance. In the high I c tapes studied, bending to 25 mm radius resulted in 1%--2% I c degradation

  11. Finite element method analysis of cold forging for deformation and densification of Mo alloyed sintered steel

    Science.gov (United States)

    Kamakoshi, Y.; Nishida, S.; Kanbe, K.; Shohji, I.

    2017-10-01

    In recent years, powder metallurgy (P/M) materials have been expected to be applied to automobile products. Then, not only high cost performance but also more strength, wear resistance, long-life and so on are required for P/M materials. As an improvement method of mechanical properties of P/M materials, a densification is expected to be one of effective processes. In this study, to examine behaviours of the densification of Mo-alloyed sintered steel in a cold-forging process, finite element method (FEM) analysis was performed. Firstly, a columnar specimen was cut out from the inner part of a sintered specimen and a load-stroke diagram was obtained by the compression test. 2D FEM analysis was performed using the obtained load-stroke diagram. To correct the errors of stress between the porous mode and the rigid-elastic mode of analysis software, the analysis of a polynominal approximation was performed. As a result, the modified true stress-true strain diagram was obtained for the sintered steel with the densification. Afterwards, 3D FEM analysis of backward extrusion was carried out using the modified true stress-true strain diagram. It was confirmed that both the shape and density of the sintered steel analyzed by new FEM analysis that we suggest correspond well with experimental ones.

  12. AC loss in stacks of Bi-2223/Ag tapes modified with ferromagnetic covers at the edges

    Energy Technology Data Exchange (ETDEWEB)

    Safran, S; Goemoery, F [Institute of Electrical Engineering, Slovak Academy of Sciences, Dubravska cesta 9, 842 39 Bratislava (Slovakia); Gencer, Ali [Physics Department, Faculty of Sciences, Ankara University, Tandogan, 06100 Ankara (Turkey)

    2010-10-15

    We investigated the magnetization loss of stacked Bi-2223/Ag tapes with a ferromagnetic cover on the edges. Such modification has been found recently to reduce the AC loss of a single tape; however, the behavior in a coil winding could be different. With experiments and numerical calculations we show that a ferromagnetic cover on the edges of a superconducting tape could reduce its magnetization loss also when the tapes are arranged in a stack. The effect is weaker for larger numbers of tapes but nevertheless remained significant in a stack of four tapes, which was the maximum number studied here. The effects observed experimentally are nicely explained by the results of numerical calculations.

  13. Processing and transport properties of high Jc silver clad Bi-2223 tapes and coils

    International Nuclear Information System (INIS)

    Haldar, P.; Hoehn, J.G. Jr.; Balachandran, U.

    1993-02-01

    The powder-in-tube process has been used to fabricate long lengths of flexible, high J c , silver clad Bi-2223 HTS conductors. By improving thermo-mechanical processing and precursor powder preparationwe have succeeded in achieving J c 's exceeding 4 x 10 4 A/cm 2 at liquid nitrogen (77K) and > 10 5 A/cm 2 at liquid helium (4.2K) and liquid neon (27K) temperatures for short tapesamples. Detailed measurements with high applied magnetic fields are reported. Several long tapes up to 10 meters in length have also been fabricated and co-wound into small superconducting pancake coils using the ''wind-and-react'' approach. Transport measurements at 77K and 4.2K for these coils are also reported

  14. AC-loss properties of Bi-2223 multifilamentary taped wires with a central insulation layer

    Energy Technology Data Exchange (ETDEWEB)

    Funaki, K., E-mail: funaki@sc.kyushu-u.ac.jp [Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Nogami, K.; Kawasaki, M.; Iwakuma, M. [Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Ayai, N.; Kobayashi, S.; Kikuchi, M.; Hayashi, K. [Sumitomo Electric Industries Ltd., 1-1-3, Shimaya, Konohana-ku, Osaka 554-0024 (Japan)

    2011-11-15

    We develop twisted Bi-2223 multifilamentary taped wires with a central insulator layer. We measure the AC losses in a perpendicular magnetic field configuration. The coupling loss will be decreased by effects of twisting and the central insulator layer. The hysteresis loss in filaments will be also decreased by effects of twisting. Further efforts will be expected for increase in the current capacity. We have been developing twisted Bi-2223 multifilamentary taped wires to suppress the AC losses in perpendicular-field configuration for industrial-production process. It is confirmed that the hysteretic losses in the filamentary region can be reduced by twisting in a same manner as in situ Nb{sub 3}Sn multifilamentary ones, while the coupling loss remains in unsatisfactory situation for commercial frequency uses. As one of practical methods for further reduction of the coupling loss, we propose an advanced multifilamentary structure of the taped wires in which an insulation layer is arranged in the central region of the tape to effectively restrict the main part of the coupling current in the perpendicular-field configuration instead of an insulation barrier around each filament that may be not usually suitable to the practical production process. We have designed and fabricated prototype wires with the proposed structure, and measured the AC loss properties in the perpendicular-field configuration. The experimental results suggest that the central insulation barrier has a function to suppress the coupling loss remarkably. We also discuss improvement in the structural design for the further reduction of the AC losses.

  15. Mechanical and physical properties of Bi-2223 and Nb3Sn superconducting materials between 300 K and 7 K

    International Nuclear Information System (INIS)

    Nyilas, Arman; Osamura, Kozo; Sugano, Michinaka

    2003-01-01

    Within the framework of IEC/TC90-WG5 and VAMAS/TWA16, superconducting (SC) materials are investigated with respect to their mechanical properties between 300 K and 7 K. Besides the mechanical tests, physical and electrical properties are also determined for high T c SC-tapes. The mechanical tests comprised the characterization of tensile properties at ambient temperature as well as at 7 K of Nb 3 Sn-reacted strands, Bi2223 tapes, pure silver tapes, silver bars, silver alloy tapes and bare filaments extracted from Bi-2223 tapes. All these investigations are carried out using a variable temperature helium gas flow cryostat equipped with a servo hydraulic tensile machine (MTS, model 810). For the load measurements specially developed, highly sensitive cryogenic proof in situ working load cells are used. For the strain determination of the wires, a high resolution ultra-light double extensometer system with a specially developed low noise signal conditioner is used. The engineering parameters such as yield strength and elastic modulus are evaluated using the obtained data with newly developed software. For the tiny and brittle filaments load versus displacement data are obtained. A determined master line (Young's modulus versus machine compliance) established by thin 0.125 mm O wires of different pure metals is used for the Young's modulus estimation of filaments. For the 4 K electrical voltage-current measurements under magnetic fields of up to 13 T, an existing test facility is used for the high T c tapes. No dependency between applied strain up to 0.3% and the critical current under magnetic field could be observed for the selected specific Bi-2223 tapes. In addition, thermal expansion curves of Bi-2223 tapes along with pure silver and silver alloy (AgMg) are determined between 290 K and 7 K using in situ working extensometers. The coefficient of thermal expansion is evaluated by the determined thermal expansion versus temperature curve

  16. Effect of lead content on phase evolution and microstructural development in Ag-clad Bi-2223 composite conductors

    International Nuclear Information System (INIS)

    Merchant, N.N.; Maroni, V.A.; Fischer, A.K.; Dorris, S.E.; Zhong, W.; Ashcom, N.

    1997-02-01

    A two powder process was used to prepare silver-sheathed monofilamentary Bi 1.8 Pb x Sr 1.98 Ca 1.97 Cu 3.08 O y (Bi-2223) tapes with varying lead contents, x, from 0.2 to 0.5. The resulting tapes were subjected to thermomechanical processing and then characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray analysis (EDX). Layered phase texture was accessed using image analysis software on scanned SEM micrographs. Transport currents were measured at 77 K and zero field by the four-probe method. It was found that tapes with low lead content (X = 0.2 and 0.25) showed incomplete conversion to Bi-2223, had small grain size and poor c-axis texture. Tapes having higher lead content (x = 0.4 and 0.5) also showed incomplete conversion and the presence of lead-rich secondary phases. Tapes with lead content x = 0.3 and 0.35 showed complete conversion to Bi-2223, and had the least amount of secondary phases, the best c-axis texture, and the highest transport current (j c ). The carbon content of the precursor powder also had a strong influence on secondary-phase chemistry

  17. Strain reduced critical current in Bi-2223/Ag superconductors under axial tension and compression

    International Nuclear Information System (INIS)

    Haken, B. ten; Godeke, A.; Kate, H.H.J. ten

    1997-01-01

    The critical current of Ag sheathed Bi(Pb)SrCaCuO-2223 tape conductors is investigated as a function of various strain components. A reduction of the critical current occurs due to both tensile or a compressive strain. The critical current reduction is qualitatively similar with the results as observed in Bi-2212 conductors. An axial compression leads to an immediate critical current reduction. The critical current in an axially elongated sample remains nearly constant up to a certain limit typically close to 0.3% strain. For a larger elongation the critical current reduces rapidly. A transverse pressure acting on the tape surface leads also to an irreversible critical current reduction. This behavior is compared with the influence of an axial compression with an effective Young's modulus. The deformation induced critical current reductions in Bi-2223 conductors can be described by a model that is already proposed for Bi-2212 conductors. This model is based on the irreversible nature of the critical current reduction due to a certain deformation

  18. Electrical and mechanical properties of Bi-2223/Ag/barrier/Ag composite tapes

    International Nuclear Information System (INIS)

    Kovac, P.; Husek, I.; Goemoery, F.; Oduleye, O.O.; Alford, N.McN.; Pachla, W.; Diduszko, R.

    2000-01-01

    Bi-2223/Ag/barrier/Ag single-core tapes with various oxide barrier materials (BaZrO 3 , SrCO 3 , ZrO 2 and Al 2 O 3 ) have been prepared by PIT. The I-V curves and ac susceptibility measurements have been performed for tapes with identical heat treatment history. Young's moduli of these tape samples have been evaluated by three-point bending and the structure of barrier powders and BSCCO cores was analysed by SEM and XRD, respectively. It was found that the shape of I-V curves, the current transfer lengths and the mechanical properties of tapes are all affected by the oxide barrier type and the barrier thickness, as well as by its porosity and uniformity. This is because the oxide barrier controls the oxygen diffusion during the tape heat treatment and simultaneously the HTS phase formation kinetics, its purity and content within the superconducting core. On the base of the results obtained for single-core tapes, two kinds of multifilamentary composite were made and tested. (author)

  19. High-temperature superconducting magnets and coils from silver-sheathed Bi-2223 tapes

    International Nuclear Information System (INIS)

    Haldar, P.; Hoehn, J.G. Jr.; Motowidlo, L.R.; Balachandran, U.

    1994-01-01

    Long lengths (30 to 100 m) of silver-sheathed Bi-2223 tapes with high critical current density(J c ) were fabricated by the conventional powder-in-tube technique and used to make compact and robust coils by the wind-and-react approach. The tapes were insulated, co-wound in parallel, and heat treated to produce a fused conductor of larger cross section in the form of pancake coils that were stacked in series to make test magnets. The coils and test magnets were characterized at liquid nitrogen (77 K) and liquid helium (4.2 K) temperatures. The highest field generated by the test magnets was 0.36 T at 77 K and 2.6 T at 4.2 K. Progress in the prototype manufacturing of long lengths of HTS tape conductor is also discussed. Lengths of 30 to 100 m are now being made, and 70 m lengths were observed to carry 23 A (J c ∼ 15,000 A/cm 2 ) when immersed in liquid nitrogen

  20. Phase relations study on the melting and crystallization regions of the Bi-2223 high temperature superconductor

    Directory of Open Access Journals (Sweden)

    Polasek Alexander

    2004-01-01

    Full Text Available The melting and solidification behavior of Bi2Sr2Ca2Cu3 O10 (Bi-2223 precursors has been studied. Nominal compositions corresponding to excess of liquid, Ca2CuO3 and CuO have been investigated. Each sample was made by packing a precursor powder into a silver crucible, in order to approximately simulate the situation found in 2223 silver-sheathed tapes. The samples were partially melted and then slow-cooled, being quenched from different temperatures and analyzed through X-ray diffraction (XRD and scanning electron microscopy (SEM/EDS. The precursors decomposed peritectically during melting, forming liquid and solid phases. Very long plates with compositions falling in the vicinity of the 2223 primary phase field formed upon slow-cooling. The 2223 phase may have been formed and the results suggest that long grains of this phase might be obtained by melting and crystallization if the exact peritectic region and the optimum processing conditions are found.

  1. Geometry dependence of magnetic and transport AC losses in Bi-2223/Ag tapes with different aspect ratios

    International Nuclear Information System (INIS)

    Fang, J; Luo, X M; Chen, D X; Alamgir, A K M; Collings, E W; Lee, E; Sumption, M D; Fang, J G; Yi, H P; Song, X H; Guo, S Q; Liu, M L; Xin, Y; Han, Z

    2004-01-01

    On five Bi-2223/Ag tapes with different aspect ratios from 5 to 26, AC losses have been measured at 77 K while a parallel AC magnetic field or a perpendicular AC magnetic field or a longitudinal AC transport current is applied. It has been found that at any frequency the perpendicular magnetic losses per cycle increase, but the parallel magnetic losses per cycle and the transport losses per cycle decrease as the aspect ratio increases. These experimental results are in accord with theoretical results. Meanwhile, we investigated the geometry dependence of the decay time constant of coupling current and that of full penetration field

  2. Geometry dependence of magnetic and transport AC losses in Bi-2223/Ag tapes with different aspect ratios

    Energy Technology Data Exchange (ETDEWEB)

    Fang, J [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Luo, X M [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Chen, D X [ICREA and Grup Electromagnetisme, Departament de Fisica, Universitat Autonoma Barcelona, 08193 Bellaterra (Spain); Alamgir, A K M [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Collings, E W [MSE, Ohio State University, Columbus, OH 43210 (United States); Lee, E [MSE, Ohio State University, Columbus, OH 43210 (United States); Sumption, M D [MSE, Ohio State University, Columbus, OH 43210 (United States); Fang, J G [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Yi, H P [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Song, X H [Innova Superconductor Technology Co., Ltd, 7 Rongchang Dongjie, Longsheng Industrial Park, Beijing Economic and Technological Development Area, 100176 (China); Guo, S Q [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Liu, M L [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Xin, Y [Innopower Superconductor Cable Co., Ltd, 7 Rongchang Dongjie, Longsheng Industrial Park, Beijing Economic and Technological Development Area, 100176 (China); Han, Z [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China)

    2004-10-01

    On five Bi-2223/Ag tapes with different aspect ratios from 5 to 26, AC losses have been measured at 77 K while a parallel AC magnetic field or a perpendicular AC magnetic field or a longitudinal AC transport current is applied. It has been found that at any frequency the perpendicular magnetic losses per cycle increase, but the parallel magnetic losses per cycle and the transport losses per cycle decrease as the aspect ratio increases. These experimental results are in accord with theoretical results. Meanwhile, we investigated the geometry dependence of the decay time constant of coupling current and that of full penetration field.

  3. Strain control of composite superconductors to prevent degradation of superconducting magnets due to a quench: II. High-strength, laminated Ag-sheathed Bi-2223 tapes

    Science.gov (United States)

    Shen, Tengming; Ye, Liyang; Higley, Hugh

    2018-01-01

    In article I of this series, we described a spiral coil quench technique for probing the influence of the superconductor stress and strain state during normal operation on its margin to degradation during a quench and applied to a Bi-2212 round wire. Here we extend this technique to study the failure mechanisms and limits of high-strength Bi-2223 tapes experiencing a quench while carrying a large current in a high magnetic field. In contrast to Bi-2212 magnets made via a wind-and-react technique for which bending strains can be ignored, Bi-2223 magnets are made with a react-and-wind technique for which bending strain is significant. The critical tensile stress of Bi-2223 tapes (type HT-NX) decreases from >440 MPa for straight samples to 185 MPa after being bent to a diameter D of 50 mm. For HT-NX tapes with D = 50 mm, the quench degradation limit, measured using maximum allowable temperature during a quench T allowable, is greater than 300 K for axial tensile stress {σ }a < 94 MPa; it decreases with increasing tensile axial stress {σ }a nonlinearly, dropping to 230 K for {σ }a = 125 MPa. T allow able ({σ }a) experimental data at D = 50 mm is consistently predicted by a general strain model that assumes that quench degradation in NX/Bi-2223 is driven by axial tensile strain in Bi-2223 filaments exceeding the irreversible strain limit. The T allowable ({σ }a) is then predicted for various D including D = 80 mm important for NMR magnets. The given T allowable (D,{σ }a) is easy to use and important for finding the balance between operation stress, and therefore magnetic field generation efficiency, and operation margin when designing a superconducting magnet using Bi-2223 tapes.

  4. The impact of Fe doping on J sub c behavior of Bi2223/Ag tapes under magnetic field

    CERN Document Server

    Xiao, H; Song, W H; Du, J J; Sun, Y P

    2002-01-01

    Bi sub 1 sub . sub 8 Pb sub 0 sub . sub 4 Sr sub 2 Ca sub 2 sub . sub 2 Cu sub 3 sub - sub x Fe sub x O sub y silver-sheathed (Bi2223/Ag) tapes with different Fe-doping amounts, x=0.001, 0.002, 0.003, 0.004, were fabricated by powder-in-tube (PIT) technique. It is found that the magnetic field dependence of critical current density J sub c (H) is improved for samples with Fe-doping amounts of x=0.001, 0.002, and 0.003 at high magnetic fields, while the J sub c (H) behavior deteriorates with Fe-doping level increasing further. X-ray diffraction analyses manifest that a small amount of Fe-doping has little effect on the phase composition of Bi2223/Ag tapes. Scanning electron microscopy (SEM) observations do not show an obvious difference between un-doped and Fe-doped samples. It is concluded that the enhanced flux pinning originates from the introduction of effective pinning centers due to Fe ions partial substitution for Cu ions. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  5. An upper bound solution for closed die sinter forging of hexagonal ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    It is expected that the present work will be of great importance for the assessment of die load during the forging of metal powder preforms. 2. Interfacial friction law. In investigation of the plastic deformation of metal-powder preforms, it is evident that with the application of compressive hydrostatic stress the pores close and ...

  6. Ba2ErNbO6: A new perovskite ceramic substrate for Bi(2223 ...

    Indian Academy of Sciences (India)

    Unknown

    110 K and current density of ~ 4 × 103 A cm–2 at 77 K and zero magnetic field. Keywords. Barium erbium niobate; perovskite; substrate; sintering; superconducting film. 1. Introduction. High-Tc superconducting thick films have wide ... The physical properties of BENO are sum- marized in table 1. *Author for correspondence ...

  7. Soldering of Bi-2223/Ag high temperature superconducting tapes with Sn-Pb-Bi-Ag alloy paste

    Energy Technology Data Exchange (ETDEWEB)

    Guo Wei, E-mail: gwei@tsinghua.edu.c [Department of Mechanical Engineering, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Tsinghua University, Ministry of Education of PR China, Beijing 100084 (China); School of Mechanical Engineering and Automation, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Zou Guisheng; Wu Aiping; Bai Hailin; Ren Jialie [Department of Mechanical Engineering, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Tsinghua University, Ministry of Education of PR China, Beijing 100084 (China)

    2010-01-15

    Soldered joints of Bi-2223/Ag-sheathed high temperature superconducting multifilamentary tapes were fabricated using 63 wt.%Sn-34 wt.%Pb-1 wt.%Bi-2 wt.%Ag paste. The soldered joints were observed by scanning electron microscope (SEM) and X-ray diffraction (XRD). Moreover, the electrical properties of joints were evaluated by current-voltage curves, and the tensile strengths of the joints were also tested. The results show that the soldered joint consists of Ag sheath - Ag{sub 3}Sn compound layer - PbSn{sub 2} and Ag{sub 3}Sn solder layer - Ag{sub 3}Sn compound layer - Ag sheath. The joints are obeyed with Ohms Law and the magnitude of the joint resistance, which deceases with the increase of the overlap length, can reach the order of 10{sup -8} OMEGA. The tensile strength of the joints with a brittle fracture mode is a little lower than that of the original tapes.

  8. Fabrication, properties, and microstructures of high Tc tapes and coils made from Ag-clad Bi-2223 superconductors

    International Nuclear Information System (INIS)

    Balachandran, U.; Iyer, A.N.; Youngdahl, C.A.; Motowidlo, L.R.; Hoehn, J.G.; Haldar, P.

    1993-07-01

    Bi-2223 precursor powders were prepared via a solid-state reaction using carbonates and oxides of Bi, Pb, Sr, Ca, and Cu. Results indicate that an in-situ reaction between constituent phases with tho formation of a transient liquid that is consumed during final heat treatment, is essential to obtain increased density with greater connectivity between the 2223 grains. Relative amounts of the constituent phases were adjusted in the powder by varying the calcination conditions, and the powder was then used to fabricate Ag-clad tapes by a powder-in-tube technique. By improving process conditions, transport critical current density (J c ) values greater than 4 x 10 4 A/cm 2 at 77 K and 2 x 10 5 A/cm 2 at 4.2 and 27 K have been obtained in short tape samples. Long tapes were cut into lengths upto 10 m long and used in parallel to fabricate small superconducting pancake coils. The coils were characterized at 77, 27 and 4.2 K and results are discussed

  9. A round robin test for pre-standardization of a saddle-shaped pickup coil method to measure AC losses in Bi-2223 Ag-sheathed tapes

    Energy Technology Data Exchange (ETDEWEB)

    Funaki, K. [Research Institute of Superconductor Science and Systems, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan)], E-mail: funaki@sc.kyushu-u.ac.jp; Iwakuma, M.; Sueyoshi, T. [Research Institute of Superconductor Science and Systems, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Fujikami, J.; Ayai, N.; Ishida, T. [Sumitomo Electric Industries Ltd., 1-1-3, Shimaya, Konohana-ku, Osaka 554-0024 (Japan); Tanaka, Y. [International Superconductivity Technology Center, 5-34-3 Shinbashi, Minato-ku, Tokyo 105-0004 (Japan); Osamura, K. [Research Institute for Applied Sciences, 49 Tanaka Ohicho, Sakyo-ku, Kyoto 606-8202 (Japan)

    2008-09-15

    We performed a round robin test to measure AC losses in Bi-2223 Ag-sheathed tapes with saddle-shaped pickup coils in an alternating perpendicular magnetic field at liquid nitrogen temperature. Two laboratories participated in the round robin test with each system of the pickup coil and the measurement circuit. Short specimens of a Bi-2223 tape and a copper magnet to generate the alternating magnetic field were used for common conditions in the test. The saddle-shaped pickup coils were made under recommended conditions for the structure and the sizes that give a calibration coefficient around unity. The signals of the magnetic moment from the pickup coils were calibrated by using a standard hairpin copper tape. AC losses of the common specimen of the Bi-2223 tape were measured in the round robin test in the ranges of frequency up to 60 Hz and the amplitude up to 0.2 T of perpendicular magnetic field. While we had only two participants in the test, we obtained the following results in a pre-standardization process of the AC loss measurement with the saddle-shaped pickup coil (i) it was suggested from the calibration procedure using hairpin copper tape that the deviations from numerical simulation for an ideal pickup coil and a sufficiently long specimen is within 3% on an average, (ii) the values of COV for the AC losses measured at 1 Hz and 10 Hz are less than about 3% in the range of the field amplitude between 0.02 T and 0.2 T.

  10. Locating of normal transitions in a Bi2223 high temperature superconducting coil by using capacitor type voltage terminals and the active power method

    Science.gov (United States)

    Nanato, N.; Okura, K.; Kumagai, H.; Aoyama, H.

    2017-07-01

    It is important to locate positions of normal transitions in a high temperature superconducting (HTS) coil for identifying its design and fabrication weakness. In this paper, the authors propose a locating method by using capacitor type voltage terminals and the active power method. The former is a method to measure voltage in a HTS coil without electric contact and the latter is a method to detect the normal transitions by measuring active power dissipated in the coil. Combination of the two methods can achieve precise location of the normal transitions. The authors show usefulness of the method through experimental results for a Bi2223 HTS coil.

  11. (119) Bi-2223 thin films grown by MOCVD on (100) NdGaO3 and (110) SrTiO3

    Science.gov (United States)

    Endo, Kazuhiro; Badica, P.

    2002-11-01

    In high temperature superconductors (HTS) the coherence length along non-c axis directions is longer. This feature can be useful wh en designing electronics devices based on HTS. Therefore growth and characterization of non-c axis oriented thin HTS films is of great interest. In this paper we present a short review of our data regarding (119) Bi-2223 thin films grown by MOCVD on (100) NdGaO3 and (110) SrTiO3. The emphasis is made on improvement and control of the quality of the films by the "two-temperature" technological approach and/or use of the vicinal substrates. Phase and morphology evolution for different processing conditions, substrate's type and off-angle are presented. The highest critical temperatures of Tc0=67.2 K and Tc0=74 K for the "single" and "two-"temperature routes were obtained on vicinal SrTiO3 with the off-angle of 20°. A higher off-angle promoted the formation of a specific step-like morphology with lower roughness. For the films grown on flat substrates the morphology was of mountain-range shape. Surface morphology as a result of two types of growth mechanisms (two-dimensional (2D), assisted by a so-called "twin"-growth and step-flow growth) for the (119)Bi-2223 filmes are discussed.

  12. Basic study for a large AC current supply with a single phase air-core Bi2223 high temperature superconducting transformer

    Science.gov (United States)

    Nanato, N.; Kishi, N.; Tanaka, Y.; Kondo, M.

    2017-07-01

    The authors have been developing a compact power supply with a single-phase Bi2223 high temperature superconducting (HTS) transformer. The conventional transformer has an iron-core for enhancing magnetic coupling between its primary coil and secondary one. However, the iron-core has great majority of size and weight of the transformer and therefore it is desirable to be removed for a smaller and lighter transformer. In this paper, the authors propose an air-core HTS transformer for a more compact power supply than the conventional one. As experimental results, it is shown that appropriate design of the air-core transformer has a possibility to decrease the weight and volume of the large AC current supply.

  13. Effect of ion-irradiation on the microstructure and microhardness of the W-2Y2O3 composite materials fabricated by sintering and hot forging

    International Nuclear Information System (INIS)

    Battabyal, M.; Spätig, P.; Baluc, N.

    2013-01-01

    Highlights: • W-2Y 2 O 3 material is fabricated using sintering and hot forging method with 99.3 vol.% density. • Microstructure and microhardness of the material after heavy ion irradiation are almost similar irrespective of the sample holder heating temperatures. • Dislocation loops are found on the W grains of irradiated sample where as radiation induced fine voids are observed on yttria particles. • We also observe few radiation loops on yttria particles. • No surface crack at the grain boundary is observed and significant difference in radiation hardening is confirmed. -- Abstract: A W-2Y 2 O 3 material was developed in collaboration with the Plansee Company (Austria). An ingot of the material having approximate dimension of 95 mm × 20 mm was fabricated by mixing the elemental powders followed by pressing, sintering and hot forging. The microstructure of the W-2Y 2 O 3 composite was investigated using transmission electron microscopy (TEM). The microhardness was studied using nano-indentation technique. We observed that the W-grains having a mean size of about 1 μm already formed and these grains contain very low density of dislocations. The size of the yttria particles was between 300 nm and 1 μm and the Berkovich hardness was about 4.8 GPa. The specimens were irradiated/implanted with Fe and He ions at JANNuS facility located at Orsay/Saclay, France. The TEM disks kept were irradiated/implanted at 300 and 700 °C using Fe and He ions with an energy of 24 and 2 MeV, respectively. The calculated radiation dose was about 5 dpa produced by Fe ions and total He content is 75 appm at both 300 and 700 °C. From the TEM investigation of irradiated samples, few radiation loops are present on the W grains, whereas on yttria particles, the radiation induced damages appear as voids. Berkovich hardness of the irradiated sample is higher than that of the non-irradiated sample. Results on the microstructure and microhardness of the ion-irradiated W-2Y 2 O 3

  14. Study of ac loss in Bi-2223/Ag tape under the simultaneous action of ac transport current and ac magnetic field shifted in phase

    International Nuclear Information System (INIS)

    Vojenciak, M; Souc, J; Ceballos, J M; Goemoery, F; Klincok, B; Pardo, E; Grilli, F

    2006-01-01

    Investigation of ac loss under the simultaneous action of the transport ac current and the external ac magnetic field is of prime importance for the reliable prediction of dissipation in electric power devices such as motors/generators, transformers and transmission cables. An experimental rig allowing us to perform ac loss measurements in such conditions, on short (10 cm) tape samples of high-temperature superconductor Bi-2223/Ag, was designed and tested. Both the electromagnetic and thermal methods were incorporated, allowing us to combine the better sensitivity of the former and the higher reliability of the latter. Our main aim was to see how the ac loss depends on the phase shift between the transport current and the external magnetic field. Such a shift could have different values in various applications. While in a transformer winding, the maximum phase shift at full load will probably not exceed a few degrees, in a three phase transmission cable in tri-axial configuration it is around 120 0 . Therefore, we explored the whole range of phase shifts from 0 to 360 0 . Surprisingly, the maxima of dissipation did not coincide with zero shift as expected from qualitative considerations

  15. Significant reduction in AC transport self-field losses of Ag-sheathed Bi2223 tapes achieved by changing filament arrangements

    Science.gov (United States)

    Oota, A.; Inada, R.; Inagaki, N.; Ogawa, Y.; Nakamura, Y.; Fukunaga, T.; Zhang, P. X.

    2004-05-01

    Significant reduction in AC transport self-field losses has been achieved at 77 K for Ag-sheathed Bi2223 multifilamentary tapes with m × n (m,n = 3 or 5) filament arrangements, fabricated via a rectangular deformation process using two-axis rollers. This achievement is not effected by introducing resistive barriers but by changing filament arrangements. Despite the main contribution being the hysteresis loss of the superconductor, the loss values are decreased by approximately 50-70%, compared with the values for multifilamentary tapes obtained by a standard powder-in-tube process. More complicated filament arrangements achieved via a rectangular deformation process lead to further reduction in the loss values. On the basis of numerical calculations, the loss reduction is mainly ascribed to a division of the field-free core in the filament groups near the tape edge under AC current transmission. The study should pave the way to removing an obstacle to loss reduction and to developing tape strands with low loss values satisfying practical demands.

  16. Significant reduction in AC transport self-field losses of Ag-sheathed Bi2223 tapes achieved by changing filament arrangements

    International Nuclear Information System (INIS)

    Oota, A; Inada, R; Inagaki, N; Ogawa, Y; Nakamura, Y; Fukunaga, T; Zhang, P X

    2004-01-01

    Significant reduction in AC transport self-field losses has been achieved at 77 K for Ag-sheathed Bi2223 multifilamentary tapes with m x n (m,n = 3 or 5) filament arrangements, fabricated via a rectangular deformation process using two-axis rollers. This achievement is not effected by introducing resistive barriers but by changing filament arrangements. Despite the main contribution being the hysteresis loss of the superconductor, the loss values are decreased by approximately 50-70%, compared with the values for multifilamentary tapes obtained by a standard powder-in-tube process. More complicated filament arrangements achieved via a rectangular deformation process lead to further reduction in the loss values. On the basis of numerical calculations, the loss reduction is mainly ascribed to a division of the field-free core in the filament groups near the tape edge under AC current transmission. The study should pave the way to removing an obstacle to loss reduction and to developing tape strands with low loss values satisfying practical demands

  17. Conceptual design of a forced-flow-cooled 20-kA current lead using Ag-alloy-sheathed Bi-2223 high-temperature superconductors

    International Nuclear Information System (INIS)

    Heller, R.

    1994-11-01

    The use of high-temperature superconductors in current leads to reduce refrigeration power has been investigated by many groups in the past. Most used YBCO and Bi-2212 bulk superconductors, although their critical current density is not very high. In this paper, BI-2223 HTSC tapes sheathed with Ag alloys are used in the design of a 20-kA current lead because of their higher critical current in medium magnetic fields. The lead current of 20 kA is related to the coil current of the planned stellarator WENDELSTEIN 7-X. Forced-now helium cooling has been used in the design, allowing position-independent and well-controlled operation. The design characteristics of the lead are presented and 4-K helium cooling of the whole lead, as well as 60-K helium cooling of the copper part of the lead, is discussed. The power consumption at zero current, and the lead's behaviour in case of loss of coolant flow, are given, The results of the design allow extrapolation to current leads of the 50-kA range

  18. Effect of Fast Neutron Irradiation on the Properties of a Superconducting (Bi-2223+0.8% 238U)/Ag-Tape

    CERN Document Server

    Goncharov, I N; Voloshin, I F; Kalinov, A V; Fisher, L M

    2001-01-01

    The critical current density (J_c) of a high temperature superconductor doped with uranium can be significantly increased due to neutron irradiation which results in the production of fission fragment tracks. The disadvantages of such a method in case of enriched U introducing into the Bi-2223/Ag-tape are analysed in this paper. The main of them is a high level of long-lived radioactivity after thermal neutron irradiation. The alternative method, in which unenriched uranium introduced into HTS is irradiated with fast neutrons of a>1.4 MeV energy has been checked experimentally. There was a very small fraction of slow neutrons in the reactor beam. At liquid nitrogen temperatures, increasing J_c was found to be observed only at B>0.5 T and for low enough fluences F_n (as compared with the calculated optimum one). For higher F_n, the values of J_c degraded at any B though the radioactivity level is much lower than in the method, where thermal neutrons are used.

  19. Influence of powder pre-annealing on the phase formation and critical current of Bi-2223/Ag tapes

    DEFF Research Database (Denmark)

    Chen, X.P.; Grivel, Jean-Claude; Li, M.Y.

    2004-01-01

    the precursor with Ca2PbO4 phase (tape T1) had lower transformation rate of 2223 phase than tapes fabricated using the precursor with 3321 phase (tape T2). SEM results show that a large fraction of secondary phases with big particle size was formed in the tape T1 during the subsequent sintering, which might....... The effects of different precursors were investigated by XRD, SEM/EDS and critical current measurements. It has been found that both the microstructure and phase formation depended strongly on the different lead-rich phases, which determined the reactivity of the precursor. Tapes fabricated using...... degrade the critical current of the tapes. On the contrary, a small amount of secondary phases with small particle size was formed in the tape T2. Consequently, the critical current of tape T1 was lower than that of tape T2. (C) 2004 Elsevier B.V. All rights reserved....

  20. Liquid helium boil-off measurements of heat leakage from sinter-forged BSCCO current leads under DC and AC conditions

    International Nuclear Information System (INIS)

    Cha, Y.S.; Niemann, R.C.; Hull, J.R.; Youngdahl, C.A.; Lanagan, M.T.; Nakade, M.; Hara, T.

    1995-06-01

    Liquid helium boil-off experiments are conducted to determine the heat leakage rate of a pair of BSCCO 2223 high-temperature superconductor current leads made by sinter forging. The experiments are carried out in both DC and AC conditions and with and without an intermediate heat intercept. Current ranges are from 0-500 A for DC tests and 0-1,000 A rms for AC tests. The leads are self-cooled. Results show that magnetic hysteresis (AC) losses for both the BSCCO leads and the low-temperature superconductor current jumper are small for the current range. It is shown that significant reduction in heat leakage rate (liquid helium boil-off rate) is realized by using the BSCCO superconductor leads. At 100 A, the heat leakage rate of the BSCCO/copper binary lead is approximately 29% of that of the conventional copper lead. Further reduction in liquid helium boil-off rate can be achieved by using an intermediate heat intercept. For example, at 500 K, the heat leakage rate of the BSCCO/copper binary lead is only 7% of that of the conventional copper lead when an intermediate heat intercept is used

  1. A 13 kA current lead, measuring 1.5 m in length. The lower part consists of a high-temperature superconductor (Bi-2223), operating at between 50 K and 4.5 K, while the heat-exchanger upper part allows the current to be brought from room temperature to 50 K.

    CERN Multimedia

    2004-01-01

    A 13 kA current lead, measuring 1.5 m in length. The lower part consists of a high-temperature superconductor (Bi-2223), operating at between 50 K and 4.5 K, while the heat-exchanger upper part allows the current to be brought from room temperature to 50 K.

  2. The changes on microstructure and electrical properties of Bi:2223/Ag composite as a function of the granulation and the content of the added silver powder

    International Nuclear Information System (INIS)

    Santos, D.I. dos; Zanata, L.A.G.; Nunes, C.C.; Saeki, M.J.

    2005-01-01

    The Bi-Sr-Ca-Cu-O system has been one of the most studied superconducting ceramic materials for industry applications. The most of the studies with this aim are on silver/ceramic composites, due to the benefits and great compatibility of this metal with the oxide. In this paper we describe a systematic and comparative study on Ag/BSCCO composite, made by the citrate route, in which the ceramic pellets are sintered in the presence of silver powder using several proportions and having several granulations. It was observed that the introduction of fine (0.5 and 2 μm) silver powder in the proportions of 5 wt.% always implies in a better critical current density compared to the no silver pellet. According to the results, the silver powder in excess of 5 wt.% may not promote best electrical properties, depending on the size of the silver particles. (orig.)

  3. Improvement of Bi-2223/Ag tape performances through the control of the Pb-rich phases present in the precursors powders

    DEFF Research Database (Denmark)

    Chen, X.P.; Grivel, Jean-Claude; Li, M.Y.

    2004-01-01

    Precursor powders containing different lead-rich phases: (a) Ca2PbO4, (b) Pb-3(Sr,Bi)(3)Ca2CuOy (3321), were prepared by controlling the calcination temperature and atmosphere. Monofilament tapes were fabricated using those two powders. It has been found that both the microstructure and critical...... current depended strongly on the nature of the lead-rich phase. Tapes fabricated using the precursor with the Ca2PbO4 phase (tape T1) had a much lower optimum sintering temperature and a narrower temperature window than tapes fabricated using the precursor with the 3321 phase (tape T2). The critical...... current density J(c), of tape T2 is improved by a factor 1.5-2. SEM results show that a large fraction of secondary phases with big particle size was formed in the fully reacted tape TI, which might degrade the critical current of these tapes. On the contrary, little and small secondary phases were formed...

  4. Role of vanadium in Bi-2223 ceramics

    Indian Academy of Sciences (India)

    Previous reports ([1–7] and also, [9]) on V-substituted samples of Bi2Sr2Ca2Cu3Os have mostly pointed out that V ... Two series of V-substituted samples were prepared by partial replacement of V at two different sites; viz. the ..... also evaluated the phase composition on the basis of our susceptibility plots. This has also.

  5. Gd-substituted Bi-2223 superconductor

    Indian Academy of Sciences (India)

    resistivity with a view to study metal-to-insulator transition, (2) the XRD patterns of the specimens with a view to study the .... values [4] of the transition temperatures for Gd-substituted (BiPb)-2212 specimens. The specimens of Batches I and II with x > 0.4 .... (retd) P N Dheer and Dr R G Sharma. 540. Pramana – J. Phys., Vol.

  6. Modeling of Closed-Die Forging for Estimating Forging Load

    Science.gov (United States)

    Sheth, Debashish; Das, Santanu; Chatterjee, Avik; Bhattacharya, Anirban

    2017-02-01

    Closed die forging is one common metal forming process used for making a range of products. Enough load is to exert on the billet for deforming the material. This forging load is dependent on work material property and frictional characteristics of the work material with the punch and die. Several researchers worked on estimation of forging load for specific products under different process variables. Experimental data on deformation resistance and friction were used to calculate the load. In this work, theoretical estimation of forging load is made to compare this value with that obtained through LS-DYNA model facilitating the finite element analysis. Theoretical work uses slab method to assess forging load for an axi-symmetric upsetting job made of lead. Theoretical forging load estimate shows slightly higher value than the experimental one; however, simulation shows quite close matching with experimental forging load, indicating possibility of wide use of this simulation software.

  7. Sinterable powders

    International Nuclear Information System (INIS)

    Zanghi, J.S.; Kasprzyk, M.R.

    1979-01-01

    A description is given of sinterable powders and methods of producing sintered products using such powders. The powders consist of (a) a particulate ceramic material, e.g. SiC, having specified particle size and surface area; (b) a carbon source material, e.g. sugar or a phenol-formaldehyde resin; and (c) a residue from a solution of H 3 BO 3 , B 2 O 3 , or mixtures of these as sintering aid. (U.K.)

  8. A new method to fabricate Fe-TiC composite using conventional sintering and steam hammer

    OpenAIRE

    LAHOUEL, Ali; BOUDEBANE, Saïd; IOST, Alain; MONTAGNE, Alex

    2017-01-01

    International audience; The aim of this research paper is to fabricate a Fe-TiC composite by a novel and simple manufacturing method. The latter is based on two cumulative processes; a conventional sintering (transient liquid phase sintering) and a hot forging with steam hammer respectively. The blinder phase of the studied simples is varied from carbon steel to high alloy steel using alloying additive powders. The obtained outcomes showed that after the sintering process, the relative densit...

  9. New Trends in Forging Technologies

    Science.gov (United States)

    Behrens, B.-A.; Hagen, T.; Knigge, J.; Elgaly, I.; Hadifi, T.; Bouguecha, A.

    2011-05-01

    Limited natural resources increase the demand on highly efficient machinery and transportation means. New energy-saving mobility concepts call for design optimisation through downsizing of components and choice of corrosion resistant materials possessing high strength to density ratios. Component downsizing can be performed either by constructive structural optimisation or by substituting heavy materials with lighter high-strength ones. In this context, forging plays an important role in manufacturing load-optimised structural components. At the Institute of Metal Forming and Metal-Forming Machines (IFUM) various innovative forging technologies have been developed. With regard to structural optimisation, different strategies for localised reinforcement of components were investigated. Locally induced strain hardening by means of cold forging under a superimposed hydrostatic pressure could be realised. In addition, controlled martensitic zones could be created through forming induced phase conversion in metastable austenitic steels. Other research focused on the replacement of heavy steel parts with high-strength nonferrous alloys or hybrid material compounds. Several forging processes of magnesium, aluminium and titanium alloys for different aeronautical and automotive applications were developed. The whole process chain from material characterisation via simulation-based process design to the production of the parts has been considered. The feasibility of forging complex shaped geometries using these alloys was confirmed. In spite of the difficulties encountered due to machine noise and high temperature, acoustic emission (AE) technique has been successfully applied for online monitoring of forging defects. New AE analysis algorithm has been developed, so that different signal patterns due to various events such as product/die cracking or die wear could be detected and classified. Further, the feasibility of the mentioned forging technologies was proven by means

  10. Predicting sintering deformation of ceramic film constrained by rigid substrate using anisotropic constitutive law

    International Nuclear Information System (INIS)

    Li Fan; Pan Jingzhe; Guillon, Olivier; Cocks, Alan

    2010-01-01

    Sintering of ceramic films on a solid substrate is an important technology for fabricating a range of products, including solid oxide fuel cells, micro-electronic PZT films and protective coatings. There is clear evidence that the constrained sintering process is anisotropic in nature. This paper presents a study of the constrained sintering deformation using an anisotropic constitutive law. The state of the material is described using the sintering strains rather than the relative density. In the limiting case of free sintering, the constitutive law reduces to a conventional isotropic constitutive law. The anisotropic constitutive law is used to calculate sintering deformation of a constrained film bonded to a rigid substrate and the compressive stress required in a sinter-forging experiment to achieve zero lateral shrinkage. The results are compared with experimental data in the literature. It is shown that the anisotropic constitutive law can capture the behaviour of the materials observed in the sintering experiments.

  11. Instant forgedUI starter

    CERN Document Server

    Luiz, Joseandro

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks.The book is a Starter guide to learning ForgedUI. This book will start by unfolding the installation and creating a simple application using Titanium and ForgedUI, followed by taking you through the features to model an engaging UI and generate multi-platform code with Titanium, while covering the best design practice for Apple and Android application development. Last but not least, you will also come across the available resources where you can

  12. 29 CFR 1910.218 - Forging machines.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 5 2010-07-01 2010-07-01 false Forging machines. 1910.218 Section 1910.218 Labor... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.218 Forging machines. (a... other identifier, for the forging machine which was inspected. (ii) Scheduling and recording the...

  13. Precision forging technology for aluminum alloy

    Science.gov (United States)

    Deng, Lei; Wang, Xinyun; Jin, Junsong; Xia, Juchen

    2018-03-01

    Aluminum alloy is a preferred metal material for lightweight part manufacturing in aerospace, automobile, and weapon industries due to its good physical properties, such as low density, high specific strength, and good corrosion resistance. However, during forging processes, underfilling, folding, broken streamline, crack, coarse grain, and other macro- or microdefects are easily generated because of the deformation characteristics of aluminum alloys, including narrow forgeable temperature region, fast heat dissipation to dies, strong adhesion, high strain rate sensitivity, and large flow resistance. Thus, it is seriously restricted for the forged part to obtain precision shape and enhanced property. In this paper, progresses in precision forging technologies of aluminum alloy parts were reviewed. Several advanced precision forging technologies have been developed, including closed die forging, isothermal die forging, local loading forging, metal flow forging with relief cavity, auxiliary force or vibration loading, casting-forging hybrid forming, and stamping-forging hybrid forming. High-precision aluminum alloy parts can be realized by controlling the forging processes and parameters or combining precision forging technologies with other forming technologies. The development of these technologies is beneficial to promote the application of aluminum alloys in manufacturing of lightweight parts.

  14. Modelling of defects in ingot forging

    DEFF Research Database (Denmark)

    Christiansen, Peter

    The present report presents an investigation of the ingot forging process with special emphasis on modelling the influence of die geometry on the soundness of the ingot after hot forging. An investigation on how to model damage is also performed. The influence of the lower die angle is quantified...... angle of 130o-140o giving rise to the largest centreline porosity closure regardless of material hardening behaviour applied. Friction was found only to have minor influence on the optimum. Multi stroke forging operations have also been modelled since the ingot forging process consists of many forging...

  15. Reactor pressure vessel with forged nozzles

    Science.gov (United States)

    Desai, Dilip R.

    1993-01-01

    Inlet nozzles for a gravity-driven cooling system (GDCS) are forged with a cylindrical reactor pressure vessel (RPV) section to which a support skirt for the RPV is attached. The forging provides enhanced RPV integrity around the nozzle and substantial reduction of in-service inspection costs by eliminating GDCS nozzle-to-RPV welds.

  16. Experimental and finite element modeling study of co-sintering of multilayer, multifunctional ceramics

    Science.gov (United States)

    Wu, Kuan

    2007-12-01

    The co-sintering behavior of low temperature co-fired ceramics (LTCC) is investigated by combining experiment and simulation methods. The numerical method offers a way to provide quantitative information regarding the final sintered shape of multilayer ceramics, which can be used to optimize the design of multilayer, multifunctional components and help reduce tedious and expensive empirical design iterations. To predict the sintering behavior of LTCC, parameters in the viscoplastic constitutive equations for single materials (such as shear viscosity G, bulk viscosity K, and sintering stress sigma s, etc.) need to be known. An apparatus was constructed for in situ measurements of the longitudinal and radial shrinkage during free sintering and sinter forging experiments. Cylindrical samples of individual LTCC materials (DuPont 951AX, Heraeus CT-800, Ferro A6-S) were made. Free sintering and sinter-forging experiments have been performed at various heating rates and under different intermittently applied axial loads. Various methods for analyzing the data were used to extract those parameters and their dependence on temperature and relative density. The constitutive parameters obtained from experiments were then implemented in the user subroutine UMAT of the general-purpose finite element program ABAQUS to simulate the free sintering behavior of bi-layer structures (DU951/CT800) with different thickness ratios. The simulation results were then compared with the actual experimental results, which were obtained by free co-sintering bi-layer planar samples with different thickness ratios. Simulation results showed the finite element analysis was successful in predicting the shape changes and the stresses at different positions during sintering of bi-layer structures. This finite element model was also used to examine the sensitivity to various parameters of the sintering results, such as elastic Poisson's ratio v, Young's modulus E, sintering stress sigmas, shear and

  17. Optimization of the Hot Forging Processing Parameters for Powder Metallurgy Fe-Cu-C Connecting Rods Based on Finite Element Simulation

    Science.gov (United States)

    Li, Fengxian; Yi, Jianhong; Eckert, Jürgen

    2017-12-01

    Powder forged connecting rods have the problem of non-uniform density distributions because of their complex geometric shape. The densification behaviors of powder metallurgy (PM) connecting rod preforms during hot forging processes play a significant role in optimizing the connecting rod quality. The deformation behaviors of a connecting rod preform, a Fe-3Cu-0.5C (wt pct) alloy compacted and sintered by the powder metallurgy route (PM Fe-Cu-C), were investigated using the finite element method, while damage and friction behaviors of the material were considered in the complicated forging process. The calculated results agree well with the experimental results. The relationship between the processing parameters of hot forging and the relative density of the connecting rod was revealed. The results showed that the relative density of the hot forged connecting rod at the central shank changed significantly compared with the relative density at the big end and at the small end. Moreover, the relative density of the connecting rod was sensitive to the processing parameters such as the forging velocity and the initial density of the preform. The optimum forging processing parameters were determined and presented by using an orthogonal design method. This work suggests that the processing parameters can be optimized to prepare a connecting rod with uniform density distribution and can help to better meet the requirements of the connecting rod industry.

  18. Forging process design for risk reduction

    Science.gov (United States)

    Mao, Yongning

    In this dissertation, forging process design has been investigated with the primary concern on risk reduction. Different forged components have been studied, especially those ones that could cause catastrophic loss if failure occurs. As an effective modeling methodology, finite element analysis is applied extensively in this work. Three examples, titanium compressor disk, superalloy turbine disk, and titanium hip prosthesis, have been discussed to demonstrate this approach. Discrete defects such as hard alpha anomalies are known to cause disastrous failure if they are present in those stress critical components. In this research, hard-alpha inclusion movement during forging of titanium compressor disk is studied by finite element analysis. By combining the results from Finite Element Method (FEM), regression modeling and Monte Carlo simulation, it is shown that changing the forging path is able to mitigate the failure risk of the components during the service. The second example goes with a turbine disk made of superalloy IN 718. The effect of forging on microstructure is the main consideration in this study. Microstructure defines the as-forged disk properties. Considering specific forging conditions, preform has its own effect on the microstructure. Through a sensitivity study it is found that forging temperature and speed have significant influence on the microstructure. In order to choose the processing parameters to optimize the microstructure, the dependence of microstructure on die speed and temperature is thoroughly studied using design of numerical experiments. For various desired goals, optimal solutions are determined. The narrow processing window of titanium alloy makes the isothermal forging a preferred way to produce forged parts without forging defects. However, the cost of isothermal forging (dies at the same temperature as the workpiece) limits its wide application. In this research, it has been demonstrated that with proper process design, the die

  19. International cooperation in cold forging technology

    DEFF Research Database (Denmark)

    Bay, Niels; Lange, K

    1992-01-01

    International cooperation in the field of cold forging technology started in 1961 by formation of the OECD Group of Experts on Metal Forming. In 1967 this group was transformed into the International Cold Forging Group, ICFG, an independent body which has now been operative for 25 years. Members...... by cooperative activities or by instigating national research. These subgroups have produced 9 data sheets and 7 guidelines on subjects such as materials, tool design and construction, calculation methods for cold forging tools, manufacture of slugs, lubrication aspects and small quantity production. Plenary...

  20. Forging of FeAl intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Flores, O.; Juarez, J.; Campillo, B.; Martinez, L. [UNAM, Cuernavaca (Mexico). Lab. de Cuernavaca; Schneibel, J.H. [Oak Ridge National Lab., TN (United States)

    1994-09-01

    Much activity has been concentrated on the development of intermetallic compounds with the aim of improving tensile ductility, fracture toughness and high notch sensitivity in order to develop an attractive combination of properties for high and low temperature applications. This paper reports experience in processing and forging of FeAl intermetallic of B2 type. During the experiments two different temperatures were employed, and the specimens were forged after annealing in air, 10{sup {minus}2} torr vacuum and argon. From the results it was learned that annealing FeAl in argon atmosphere prior to forging resulted in better deformation behavior than for the other two environments. For the higher forging temperature used in the experiments (700C), the as-cast microstructure becomes partially recrystallized.

  1. Mechanical Testing Development for Reservoir Forgings

    Energy Technology Data Exchange (ETDEWEB)

    Wenski, E.G.

    2000-05-22

    The goal of this project was to determine the machining techniques and testing capabilities required for mechanical property evaluation of commercially procured reservoir forgings. Due to the small size of these specific forgings, specialized methods are required to adequately machine and test these sub-miniature samples in accordance with the requirements of ASTM-E8 and ASTM-E9. At the time of project initiation, no capability existed at Federal Manufacturing & Technologies (FM&T) to verify the physical properties of these reservoirs as required on the drawing specifications. The project determined the sample definitions, machining processes, and testing procedures to verify the physical properties of the reservoir forgings; specifically, tensile strength, yield strength, reduction of area, and elongation. In addition, a compression test method was also developed to minimize sample preparation time and provide a more easily machined test sample while maintaining the physical validation of the forging.

  2. Effect of Sintering Time on Superconducting Wire Bi-Pb-Sr-Ca-Cu-O With Dopant MgO Sheated Ag Using Powder in Tube Method

    Directory of Open Access Journals (Sweden)

    Hariyati Lubis

    2018-01-01

      DAFTAR PUSTAKA Abbas M.M., Abass L.K and Salman U., (2012, Influences of Sintering Time on the Tc of Bi2-xCuxPb0.3Sr2Ca2Cu3010+ High Temperature Superconductors, Energy Procedia 18, 215-224  Abbas, M.M., Abbas, L.K., Bahedh, H.S. 2015. Superconducting Properties of Bi2-SbxPb0,3Sr1,9Ba0,1Ca2Cu3O10+δ Compounds. Journal of Applied Science Research. 11. 22: 164-172 Darsono, N., Imaduddin, A., Raju, K., Yoon, D.H., (2015, Synthesis and Characterization of Bi1.6Pb0.4Sr2Ca2Cu3O7 Superconducting Oxide by High-Energy Milling, J Supercond Nov Magn. E. Chew,. (2010, Superconducting Transformer Design And Construction, University of Canterbury, Christchurch, New Zealand. March Hamadneh, I., Halim, S. A., dan Lee, C. K., (2006,  Characterization of Bi1.6Pb0.4Sr2Ca2Cu3Oy Ceramic Superconductor Prepared Via Coprecipitation Method at Different Sintering Time, J. Mater. Sci, 41: 5526-5530. Hermiz G.Y., Aljurani B.A., Beayaty M.A., (2014, Effect of Mn Substitution on the Superconducting Properties of Bi1.7Pb0,3Sr2Ca2-xMnxCu3O10+, International Journal Of Engineering and Advanced Technology (IJEAT. 3. 4: 213-217 John R Hull, (2003, Applications of high-temperature superconductors in power technology, Reports on Progress in Physics, Volume 66, Number 11 Lu, X.Y., Yi, D., Chen, H., Nagata, A. 2016. Effect of Sn, MgO and Ag2O mix-doping on the formation and superconducting properties of Bi-2223 Ag/tapes. Physics Procedia. 81: 129-132 Meretliev Sh., Sadykov K.B., Berkeliev A., (2000, Doping of High Temperature Superconductors, Turk J Phy.24: 39-48 Mohammed, N. H., Ramadhan A., Ali I. A., Ibrahim, I. H., dan Hassan, M. S, (2012, Optimizing the Preparation Conditions of Bi-2223 Superconducting Phase Using PbO and PbO2, Materials Sciences and Applications, 3: 224-233. Roumie, M., Marhaba, S., Awad R., Kork M., Hassan I., Mawassi R., (2014, Effect of Fe2O3 Nano-Oxide Addition on the Superconducting Properties of the (Bi,Pb-2223 Phase, Journal of Supercond Nov Magn, 27: 143-153 Serkan

  3. Effect of nickel addition on mechanical properties of powder forged Fe-Cu-C

    Science.gov (United States)

    Archana Barla, Nikki

    2018-03-01

    Fe-Cu-C system is very popular in P/M industry for its good compressibility and dimensional stability with high strength. Fe-Cu-C is a structural material and is used where high strength with high hardness is required. The composition of powder metallurgy steel plays a vital role in the microstructure and physical properties of the sintered component. Fe-2Cu-0.7C-Ni alloy with varying nickel composition (0%, 0.5%, 1.0%, 1.5%, 2.0%, and 3.0%) wt. % was prepared by powder metallurgy (P/M) sinter forging process. The present work discuss the effect of varying nickel content on microstructure and mechanical properties.

  4. Sintering of nonstoichiometric UO2

    International Nuclear Information System (INIS)

    Susnik, D.; Holc, J.

    1983-01-01

    Activated sintering of UO 2 pellets at 1100 deg C is described. In CO 2 atmosphere is UO 2 is nonstoichiometric and pellets from active UO 2 powders sinter at 900 deg C to high density. At 1100 deg C the final sintered density is practically achieved at heating on sintering temperature. After reduction and cooling in H 2 atmosphere which is followed sintering in CO 2 the structure is identical to the structured UO 2 pellets sintered at high temperature in H 2 . Density of activated sintered UO 2 pellets is stable, even after additional sintering at 1800 deg C. (author)

  5. Laser Sintered Calcium Phosphate Bone

    National Research Council Canada - National Science Library

    Vail, Neil

    1999-01-01

    ...) technology selective laser sintering (SLS). BME has successfully implemented a pilot facility to fabricate calcium phosphate implants using anatomical data coupled with the selective laser sintering process...

  6. A method for sintering

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention provides a method for sintering, comprising in the following order the steps of: providing a body in the green state or in the pre-sintered state on a support; providing a load on at least one spacer on the support such that the load is located above said body in the green...

  7. Sintering of beryllium oxide

    International Nuclear Information System (INIS)

    Caillat, R.; Pointud, R.

    1955-01-01

    This study had for origin to find a process permitting to manufacture bricks of beryllium oxide of pure nuclear grade, with a density as elevated as possible and with standardized shape. The sintering under load was the technique kept for the manufacture of the bricks. Because of the important toxicity of the beryllium oxide, the general features for the preliminary study of the sintering, have been determined while using alumina. The obtained results will be able to act as general indication for ulterior studies with sintering under load. (M.B.) [fr

  8. 76 FR 50755 - Heavy Forged Hand Tools From China

    Science.gov (United States)

    2011-08-16

    ... COMMISSION Heavy Forged Hand Tools From China Determinations On the basis of the record \\1\\ developed in the... antidumping duty orders on heavy forged hand tools from China would be likely to lead to continuation or... Forged Hand Tools From China: Investigation Nos. 731-TA-457-A-D (Third Review). Issued: August 10, 2011...

  9. Die forging of the alloys Az80 and Zk60

    NARCIS (Netherlands)

    Kurz, G.; Clauw, B.; Sillekens, W.H.; Letzig, D.

    2009-01-01

    Overall goal of the MagForge project is to provide tailored and cost-effective technologies for the industrial manufacturing of magnesium forged components. Scientific and technological aspects are new alloys/feedstock materials with improved performance, forging process modeling and design tools

  10. Modelling and Testing of Friction in Forging

    DEFF Research Database (Denmark)

    Bay, Niels

    2007-01-01

    Knowledge about friction is still limited in forging. The theoretical models applied presently for process analysis are not satisfactory compared to the advanced and detailed studies possible to carry out by plastic FEM analyses and more refined models have to be based on experimental testing....... The paper presents an overview of tests reported in literature and gives examples on the authors own test results....

  11. Forging national integrarion through philosophic interrogation of ...

    African Journals Online (AJOL)

    This paper argues that the recipe is philosophical re-orientation towards instituting liberalism (in the original sense of the word) as national ethos. It is also argued that liberalism is a philosophy of freedom and justice upon which anvil great civilizations have been forged and great civilizations broken when they turned ...

  12. Stainless steel forgings for nuclear chemical plants

    International Nuclear Information System (INIS)

    1982-02-01

    This Specification covers detailed requirements for the supply of austenitic stainless steel forgings used in radioactive and corrosive areas within the Nuclear Industry. With the exception of 316S51 the materials specified are all suitable for contact with nitric acid, 316S51 being included as suitable for use in contact with sodium and other alkali metals at elevated temperatures. (author)

  13. Morphological analysis and modelling of sintering and of sintered materials

    International Nuclear Information System (INIS)

    Jernot, Jean-Paul

    1982-01-01

    This research thesis addresses the study of solid phase sintering of metallic powders, and aims at describing as precisely as possible the different involved matter transport mechanisms, first by using a thermodynamic approach to sintering. Sintering diagrams are also used to determine prevailing mechanisms. The microstructure of sintered materials has been studied by using image quantitative analysis, thus by using a morphological approach to sintering. Morphological parameters allow, on the one hand, the evolution of powders during sintering to be followed, and, on the other hand, sintered products to be correctly characterised. Moreover, the author reports the study of the evolution of some physical properties of sintered materials with respect to their microstructure parameters. This leads to the development of a modelling of the behaviour of these materials [fr

  14. Sintering of Synroc D

    International Nuclear Information System (INIS)

    Robinson, G.

    1982-01-01

    Sintering has been investigated as a method for the mineralization and densification of high-level nuclear defense waste powder. Studies have been conducted on Synroc D composite powder LS04. Optimal densification has been found to be highly dependent on the characteristics of the starting material. Powder subjected to milling, which was believed to reduce the level of agglomeration and possibly particle size, was found to densify better than powder not subjected to this milling. Densities of greater than 95% of theoretical could be achieved for samples sintered at 1150 to 1200 0 C. Mineralogy was found to be as expected for Synroc D for samples sintered in a CO 2 /CO atmosphere where the Fe +2 /Fe +3 ratio was maintained at 1.0 to 5.75. In a more oxidizing, pure CO 2 atmosphere a new phase, not previously identified in Synroc D, was found

  15. SinterHab

    Science.gov (United States)

    Rousek, Tomáš; Eriksson, Katarina; Doule, Ondřej

    2012-05-01

    This project describes a design study for a core module on a Lunar South Pole outpost, constructed by 3D printing technology with the use of in-situ resources and equipped with a bio-regenerative life support system. The module would be a hybrid of deployable (CLASS II) and in-situ built (CLASS III) structures. It would combine deployable membrane structures and pre-integrated rigid elements with a sintered regolith shell for enhanced radiation and micrometeorite shielding. The closed loop ecological system would support a sustainable presence on the Moon with particular focus on research activities. The core module accommodates from four to eight people, and provides laboratories as a test bed for development of new lunar technologies directly in the environment where they will be used. SinterHab also includes an experimental garden for development of new bio-regenerative life support system elements. The project explores these various concepts from an architectural point-of-view particularly, as they constitute the building, construction and interior elements. The construction method for SinterHab is based on 3D printing by sintering of the lunar regolith. Sinterator robotics 3D printing technology proposed by NASA JPL enables construction of future generations of large lunar settlements with little imported material and the use of solar energy. The regolith is processed, placed and sintered by the Sinterator robotics system which combines the NASA ATHLETE and the Chariot remotely controlled rovers. Microwave sintering creates a rigid structure in the form of walls, vaults and other architectural elements. The interior is coated with a layer of inflatable membranes inspired by the TransHab project. The life-support system is mainly bio-regenerative and several parts of the system are intrinsically multifunctional and serve more than one purpose. The plants for food production are also an efficient part of atmosphere revitalization and water treatment. Moreover

  16. 2014 Accomplishments-Tritium aging studies on stainless steel: Fracture toughness properties of forged stainless steels-Effect of hydrogen, forging strain rate, and forging temperature

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Michael J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-02-01

    Forged stainless steels are used as the materials of construction for tritium reservoirs. During service, tritium diffuses into the reservoir walls and radioactively decays to helium-3. Tritium and decay helium cause a higher propensity for cracking which could lead to a tritium leak or delayed failure of a tritium reservoir. The factors that affect the tendency for crack formation and propagation include: Environment; steel type and microstructure; and, vessel configuration (geometry, pressure, residual stress). Fracture toughness properties are needed for evaluating the long-term effects of tritium on their structural properties. Until now, these effects have been characterized by measuring the effects of tritium on the tensile and fracture toughness properties of specimens fabricated from experimental forgings in the form of forward-extruded cylinders. A key result of those studies is that the long-term cracking resistance of stainless steels in tritium service depends greatly on the interaction between decay helium and the steels’ forged microstructure. New experimental research programs are underway and are designed to measure tritium and decay helium effects on the cracking properties of stainless steels using actual tritium reservoir forgings instead of the experimental forgings of past programs. The properties measured should be more representative of actual reservoir properties because the microstructure of the specimens tested will be more like that of the tritium reservoirs. The programs are designed to measure the effects of key forging variables on tritium compatibility and include three stainless steels, multiple yield strengths, and four different forging processes. The effects on fracture toughness of hydrogen and crack orientation were measured for type 316L forgings. In addition, hydrogen effects on toughness were measured for Type 304L block forgings having two different yield strengths. Finally, fracture toughness properties of type 304L

  17. Microstructure Evolution and Surface Cracking Behavior of Superheavy Forgings during Hot Forging

    Directory of Open Access Journals (Sweden)

    Zhenhua Wang

    2018-01-01

    Full Text Available In recent years, superheavy forgings that are manufactured from 600 t grade ingots have been applied in the latest generation of nuclear power plants to provide good safety. However, component production is pushing the limits of the current free-forging industry. Large initial grain sizes and a low strain rate are the main factors that contribute to the deformation of superheavy forgings during forging. In this study, 18Mn18Cr0.6N steel with a coarse grain structure was selected as a model material. Hot compression and hot tension tests were conducted at a strain rate of 10−4·s−1. The essential nucleation mechanism of the dynamic recrystallization involved low-angle grain boundary formation and subgrain rotation, which was independent of the original high-angle grain boundary bulging and the presence of twins. Twins were formed during the growth of dynamic recrystallization grains. The grain refinement was not obvious at 1150°C. A lowering of the deformation temperature to 1050°C resulted in a fine grain structure; however, the stress increased significantly. Crack-propagation paths included high-angle grain boundaries, twin boundaries, and the insides of grains, in that order. For superheavy forging, the ingot should have a larger height and a smaller diameter.

  18. Ba2ErNbO6: A new perovskite ceramic substrate for Bi(2223 ...

    Indian Academy of Sciences (India)

    Unknown

    The differential thermal analysis of BENO was carried out in the temperature range 30–1100°C. Differential scan- ning calorimetric studies were carried out and specific heat capacity of the material was deducted from differen- tial power curve. The thermal diffusivity of BENO was carried out by photoacoustic technique.

  19. In situ observations of crack formation in multi-filament Bi-2223 HTS tapes

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Horsewell, Andy; Skov-Hansen, P.

    2002-01-01

    High temperature superconducting tapes (BSCCO filaments embedded in Ag) were subjected to Uniaxial tension in an environmental scanning electron microscope, allowing in situ observation of cracking of the ceramic filaments. The first cracks were found to appear in the ceramic filaments at a strain...... around 0.15%, More cracks formed with increasing strain. The cracks covered the entire thickness of the filament. but did not Continue into the surrounding (ductile) Ag matrix. These 'tunnel cracks' appeared somewhat zigzag, indicating intergranular cracking mode. At low strains, crack blunting occurred...... at the ceramic/Ag interfaces of the tunnel cracks, At higher strain 'split cracks' formed at the tunnel cracks. The split cracks ran parallel with the ceramic/Ag interface just inside the ceramic layer....

  20. High critical current Ag and Ag alloy sheathed multifilament Bi-2223 tapes

    DEFF Research Database (Denmark)

    Wang, W.G.; Han, Z.; Skov-Hansen, P.

    1999-01-01

    of 0.16x2.8 mm(2) and silver/superconductor ratios of 4.4:1. By reducing the silver ratio, a J(e) of 14 kA/cm(2) with an I, of 38 A has been obtained in 55 filament tapes and an I-c of 84 A has been obtained in a tape with dimensions of 4x0.23 mm(2). A record J(c) of more than 30 kA/cm(2) with an I...

  1. Synthesis of superconductor Bi-2223 and its properties after partial oxygen substitution,

    Czech Academy of Sciences Publication Activity Database

    Jakeš, V.; Sýkorová, D.; Smrčková, O.; Vašek, Petr

    2006-01-01

    Roč. 3, č. 9 (2006), s. 3077-3080 ISSN 1610-1634 R&D Projects: GA ČR GA203/05/0114 Grant - others:Institute of Chemical Technology(CZ) 101 08 0015 Institutional research plan: CEZ:AV0Z10100521 Keywords : substitution of oxygen * superconductor * doping by fluorine Subject RIV: BM - Solid Matter Physics ; Magnetism

  2. Magnetic and structural properties of Bi(2223doped by pb and Sb

    Directory of Open Access Journals (Sweden)

    H. Salamati

    1998-04-01

    Full Text Available   In a systematic approach, we have investigated the effect of the presence of Pb and Sb in the Bi site in a BSCCO (2223 phase superconductor. There are some contradictory reports in substitution of Sb in the Bi site. Some researchers report an increase in the Tc of these materials. So, we have made an accurate stoichiometry of these superconductors and selected extra pure starting materials with appropriate ratios of Pb+Sb.   The susceptility of these samples have been measured and the structures of the systems have been studied by SEM and XRD. The results of this investigation show that, Although the presence of Pb is essential for formation of (2223 phase, but addition of small amount of Sb helps to stabilize and enhance the ratio of higher phase. Our results show that, presence of Sb would raise the critical current density, but would not affect the Tc of these superconductors.

  3. Current distribution and enhancement of the engineering critical current density in multifilament Bi-2223 tapes

    DEFF Research Database (Denmark)

    Wang, W.G.; Jensen, M.B.; Kindl, B.

    2000-01-01

    microstructure with a great amount of secondary phases. Local variation of Jc was measured within the centre segment of the tape. This indicates the influence of other factors on Jc, such as filament shape, connectivity of the filaments, and sausaging. Enhancement of Je has been pursued in which average Je of 12...

  4. Magnetic AC loss in multi-filamentary Bi-2223/Ag tapes

    NARCIS (Netherlands)

    Oomen, M.P.; Rieger, J.; Leghissa, M.; ten Kate, Herman H.J.

    1997-01-01

    The ac loss in high-Tc superconducting tapes with twisted and non-twisted filaments has been studied by a magnetic method. A brief overview of the theoretical background and the experimental set-up is presented. Measurements were made at 77 K in a magnetic field of 50 Hz frequency and 0.001-0.7 T

  5. Grain dynamics in Bi-2223 tapes measured by the 3DXRD microscope

    DEFF Research Database (Denmark)

    Poulsen, H.F.; Andersen, N.H.; Andersen, L.G.

    2002-01-01

    It is demonstrated how a novel X-ray diffraction method can provide information on the structural dynamics of the individual grains inside a Bi-222-3/Ag tape. A microfocused beam of 80 keV X-rays provides both the necessary spatial resolution and penetration power for in situ studies. In a feasib...

  6. Microstructural evolution at the initial stages of annealing in a Bi-2223 multifilament tape

    DEFF Research Database (Denmark)

    Liu, Y.L.; Grivel, J.-C.; Wang, W.G.

    2001-01-01

    C, as well as after 1, 2, 5, 10, 30 and 52 h at 830 degreesC. It was found that the initial liquid formation was associated with alkaline-earth cuprate (AEC) particles such as (Ca,Sr)(14)Cu24Oz and (Ca,Sr)(2)CuO3. The liquid is rich of Pb and the AEC particles dissolve and supply Cu and Ca into the liquid...... through direct contact. The 2223 kinetics are well correlated with the structural parameters of liquid and AEC particles. During the first hour the liquid activity is confined to the neighbourhood of AEC particles and the rate of 2223 formation is very low. Between 2 and 10 h the liquid amount increases...

  7. Evaluation of anisotropy of J c in silver-sheathed Bi-2223 tape

    International Nuclear Information System (INIS)

    Himeda, Y.; Kiuchi, M.; Otabe, E.S.; Matsushita, T.

    2005-01-01

    The magnetic field angle dependence of J c was measured by four probe method and DC magnetization method. The latter measurement was used for the specimen before and after bending to break the intergrain current in order to investigate only the intragrain current. It was found that the intragrain critical current density could be increased by a factor 2.7 in a parallel magnetic field when the c-axis misorientation could be improved. From the field angle dependence of the intragrain critical current density, the anisotropy parameter was estimated as 20.4

  8. Wear Analysis of Die Inserts in the Hot Forging Process of a Forked Type Forging Using Reverse Scanning Techniques

    Directory of Open Access Journals (Sweden)

    Łukasz Dworzak

    2017-12-01

    Full Text Available This article presents a wear analysis of die inserts used in the hot forging process of a forked forging (yoke, an element applied in steering systems of passenger vehicles. Studies involved the application of an original reverse scanning method intended for rapid and reliable wear analysis of forging tools (with complicated shape affording easy assessment without the need to dismount tools from the forging unit. The developed method involves analysis of progressive wear of forging tools based on measurements (scanning of forgings periodically collected from the process and constitutes a useful tool for measurement and testing. As the authors’ earlier works have demonstrated, the proposed new approach to analysis of tool wear with the application of reverse 3D scanning has proven successful in multiple instances in the case of axially symmetrical objects. The presented results of studies indicate that it is possible to utilize the expanded method to analyze the lifetime of forging tools, including tools with complex geometry. Application of the reverse scanning method allows for continuous and practical monitoring of the condition of forging tools over the course of the forging process and should have a positive impact on improving production output and reducing production costs.

  9. Sintering of B4C by pressureless liquid phase sintering

    International Nuclear Information System (INIS)

    Rocha, Rosa Maria da; Melo, Francisco Cristovao Lourenco de

    2009-01-01

    The effect of three different sintering additive systems on densification of boron carbide powder was investigated. The sintering additives were Al 2 O 3 :Y 2 O 3 , AlN:Y 2 O 3 and BN:Y 2 O 3 compositions. Powder mixtures were prepared with 10 vol% of sintering aids following conventional powder technology processes. Samples were sintered by pressureless sintering at 2050 deg C/30min in argon atmosphere. Sintered samples were compared to a sintered B 4 C without sintering additive. Samples were characterized by XRD to analyze the crystalline phases after sintering and SEM to observe the microstructure and the second phase distribution. YB 4 and YB 2 C 2 were identified in all samples, indicating a reaction between Y 2 O 3 , B 4 C and B 2 O 3 present at the B 4 C particle surface. The best densification result was achieved with Al 2 O 3 :Y 2 O 3 additive system, showing 92.0 % of theoretical density, low porosity and 15.2 % of linear shrinkage. But this sample showed the highest weight loss. (author)

  10. An upper bound solution for closed die sinter forging of hexagonal ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    industry, as they are used successfully in a wide range of applications. ... logical aspects of the industrial processing of metal-powder preforms (Jha & Kumar 1983, ..... percentage reduction in height of preform (figure 4). Again, it increases with increasing value of D/t (figure 5). 0.0. 0.5. 1.0. 1.5. 2.0. 2.5. 2.0. 2.5. 3.0. 3.5. 4.0.

  11. The Influence of Forging Temperature on Mechanical Properties of Al-V Titanium Alloys,

    Science.gov (United States)

    Titanium alloys, *Forging, Aluminum alloys, Vanadium alloys, Mechanical properties, Heat treatment, High temperature, Press forging, Quenching, Toughness, Charpy impact tests , Notch toughness, Resistance

  12. Examples on cold forged aluminium components in automotive industry

    DEFF Research Database (Denmark)

    Bay, Niels; Kolsgaard, A.

    2000-01-01

    The present paper describes the possibilites of applying cold forging for manufacturing of light weight components in aluminium. A short description of the basic cold forming processes forms the basis for describing the great variety in design of cold forged components. Examples are mainly taken ...... from automotive industry but in a few cases also from other industrial sectors to show the possibilities....

  13. Kinematics at the Main Mechanism of a Railbound Forging Manipulator

    Directory of Open Access Journals (Sweden)

    Florian Ion Tiberiu Petrescu

    2015-09-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Heavy payload forging manipulators are mainly characterized by large load output and large capacitive load input. The relationship between outputs and inputs will greatly influence the control and the reliability. Forging manipulators have become more prevalent in the industry today. They are used to manipulate objects to be forged. The most common forging manipulators are moving on a railway to have a greater precision and stability. They have been called the railbound forging manipulators. In this paper we analyze the general kinematics of the main mechanism from a such manipulator. Kinematic scheme shows a typical forging manipulator, with the basic motions in operation process: walking, motion of the tong and buffering. The lifting mechanism consists of several parts including linkages, hydraulic drives and motion pairs. The principle of type design from the viewpoints of the relationship between output characteristics and actuator inputs is discussed. An idea of establishing the incidence relationship between output characteristics and actuator inputs is proposed. These novel forging manipulators which satisfy certain functional requirements provide an effective help for the design of forging manipulators.

  14. Forging Links for Health Research: Perspectives from the Council on ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2001-10-09

    Forging Links for Health Research: Perspectives from the Council on Health Research for Development. Book cover Forging Links for Health Research: Perspectives from the Council on Health Research for. Editor(s):. Victor Neufeld and Nancy Johnson. Publisher(s):. IDRC. October 9, 2001. ISBN: Out of print. 260 pages.

  15. The State of the Art in Cold Forging Lubrication

    DEFF Research Database (Denmark)

    Bay, Niels

    1994-01-01

    a detailed description of the state of art for lubricant systems for cold forging of C-steels and low alloy steels as well as aluminium alloys including all the basic operations such as cleaning of the slugs, application of eventual conversion coating and lubrication. As regards cold forging of steel...

  16. Development and efficiency assessment of process lubrication for hot forging

    Science.gov (United States)

    Kargin, S.; Artyukh, Viktor; Ignatovich, I.; Dikareva, Varvara

    2017-10-01

    The article considers innovative technologies in testing and production of process lubricants for hot bulk forging. There were developed new compositions of eco-friendly water-graphite process lubricants for hot extrusion and forging. New approaches to efficiency assessment of process lubricants are developed and described in the following article. Laboratory and field results are presented.

  17. Medium carbon vanadium steels for closed die forging

    International Nuclear Information System (INIS)

    Jeszensky, Gabor; Plaut, Ronald Lesley

    1993-01-01

    This work analyses the medium carbon micro alloyed vanadium potential for closed die forged production. The steels reach the mechanical resistance requests during cooling after forging, eliminating the subsequent thermal treatment. Those steels also present good fatigue resistance and machinability. The industrial scale experiments are also reported

  18. Recent development of drastically innovative BSCCO wire (DI-BISCCO)

    International Nuclear Information System (INIS)

    Kikuchi, M.; Kato, T.; Ohkura, K.; Ayai, N.; Fujikami, J.; Fujino, K.; Kobayashi, S.; Ueno, E.; Yamazaki, K.; Yamade, S.; Hayashi, K.; Sato, K.; Nagai, T.; Matsui, Y.

    2006-01-01

    Up to this day, Ag-sheathed Bi2223 superconducting wires have been widely investigated and the long wires about 1000 m have been produced by using powder-in-tube (PIT) method on a commercial basis in the various facilities or companies. Although the wires are used for some applications such as HTS cables, magnets, motor and so on, the Bi2223 wires not only require much more improvements of the superconducting properties such as critical current, mechanical properties, but also longer and more uniform wires. Recently, the performances of Bi2223 wires have been drastically improved by using Controlled Over Pressure (CT-OP) sintering process. CT-OP process increased critical current (I c ) by more than 60% at 77 K and self field and improved the mechanical strength by more than 70%. The maximum I c was increased up to 166 A. These drastic improvements were caused by the higher density of Bi2223 filament up to almost 100% and better connectivity of the Bi2223 grains. The dense structure of the Bi2223 filaments prevents the ballooning phenomenon which is caused by the gasification of the trapped liquid nitrogen during temperature rise. Additionally, higher uniformity and higher production yield of long length wire were also achieved by exterminating defects during sintering. These high performance levels in CT-OP wires have contributed commercial level applications. We call as Drastically Innovative BSCCO (DI-BSCCO)

  19. Boric oxide or boric acid sintering aid for sintering ceramics

    International Nuclear Information System (INIS)

    Lawler, H.A.

    1979-01-01

    The invention described relates to the use of liquid sintering aid in processes involving sintering of ceramic materials to produce dense, hard articles having industrial uses. Although the invention is specifically discussed in regard to compositions containing silicon carbide as the ceramic material, other sinterable carbides, for example, titanium carbide, may be utilized as the ceramic material. A liquid sintering aid for densifying ceramic material is selected from solutions of H 3 BO 3 , B 2 O 3 and mixtures of these solutions. In sintering ceramic articles, e.g. silicon carbide, a shaped green body is formed from a particulate ceramic material and a resin binder, and the green body is baked at a temperature of 500 to 1000 0 C to form a porous body. The liquid sintering aid of B 2 O 3 and/or H 3 BO 3 is then dispersed through the porous body and the treated body is sintered at a temperature of 1900 to 2200 0 C to produce the sintered ceramic article. (U.K.)

  20. Sintering of magnesia: effect of additives

    Indian Academy of Sciences (India)

    % was studied on the sinter- ing and microstructural developments of the chemically pure magnesia using the pressureless sintering technique between 1500 and 1600◦C. Sintering was evaluated by per cent densification and microstructural ...

  1. Processing and properties of mechanically alloyed sintered steels with hard inclusions

    International Nuclear Information System (INIS)

    Gutsfeld, C.

    1991-10-01

    The aim of this work was the development of mechanically alloyed sintered steels with inert hard inclusions and their characterisation concerning the mechanical properties and the sliding wear behaviour. For this material concept the hard materials NbC, TiC, TiN and Al 2 O 3 were chosen with volume contents upto 20%. Mechanical alloying of the raw powders is a necessary prerequisit for an extreme fine and homogeneous microstructure and good mechanical and wear properties. Through a connecting powder annealing a conventional powder metallurgical processing with cold pressing and sintering is possible. For the consolidation pressureless liquid phase sintering initiated through phosphorus contents of 0,6% is suitable. Because of the strong hampering of grain growth through the included hard particles sintering densities upto 99% TD are possible with extreme fine microstructures. The mechanical properties can be varied in wide ranges. So tensile strengths of 1150 MPa, elongations at fracture of 17%, hardness of over 800 HV and fatigue strengths of 370 MPa have been reached. Throughout HIP or sinter forging the mechanical properties can be improved furthermore. (orig.) [de

  2. Laser sintering of copper nanoparticles

    International Nuclear Information System (INIS)

    Zenou, Michael; Saar, Amir; Ermak, Oleg; Kotler, Zvi

    2014-01-01

    Copper nanoparticle (NP) inks serve as an attractive potential replacement to silver NP inks in functional printing applications. However their tendency to rapidly oxidize has so far limited their wider use. In this work we have studied the conditions for laser sintering of Cu-NP inks in ambient conditions while avoiding oxidation. We have determined the regime for stable, low-resistivity copper (< ×3 bulk resistivity value) generation in terms of laser irradiance and exposure duration and have indicated the limits on fast processing. The role of pre-drying conditions on sintering outcome has also been studied. A method, based on spectral reflectivity measurements, was used for non-contact monitoring of the sintering process evolution. It also indicates preferred spectral regions for sintering. Finally, we illustrated how selective laser sintering can generate high-quality, fine line (<5 µm wide) and dense copper circuits. (paper)

  3. Stress corrosion of low alloy steel forgings

    International Nuclear Information System (INIS)

    Thornton, D.V.; Mould, P.B.; Patrick, E.C.

    1976-01-01

    The catastrophic failure of a steam turbine rotor disc at Hinkley Point 'A' Power station was shown to have been caused by the growth of a stress corrosion crack to critical dimensions. This failure has promoted great interest in the stress corrosion susceptibility of medium strength low alloy steel forgings in steam environments. Consequently, initiation and growth of stress corrosion cracks of typical disc steels have been investigated in steam and also in water at 95 0 C. Cracking has been shown to occur, predominantly in an intergranular manner, with growth rates of between 10 -9 and 10 -7 mm sec. -1 . It is observed that corrosion pitting and oxide penetration prior to the establishment of a stress corrosion crack in the plain samples. (author)

  4. Designing a Tool System for Lowering Friction during the Ejection of In-Die Sintered Micro Gears

    DEFF Research Database (Denmark)

    Cannella, Emanuele; Nielsen, Emil Krabbe; Stolfi, Alessandro

    2017-01-01

    is affected by the influence of friction during the ejection phase, caused by radial expansion of the compacted and sintered powder. This paper presents the development of a pre-stressed tool system for the manufacture of micro gears made of aluminum. By using the hot isostatic pressing (HIP) sintering......The continuous improvements in micro-forging technologies generally involve process, material, and tool design. The field assisted sintering technique (FAST) is a process that makes possible the manufacture of near-net-shape components in a closed-die setup. However, the final part quality...... process and different combinations of process parameters, the designed tool system was compared to a similar tool system designed without a pre-stressing strategy. The comparison between the two tool systems was based on the ejection force and part fidelity. The ejection force was measured during...

  5. Models of current sintering

    Science.gov (United States)

    Angst, Sebastian; Engelke, Lukas; Winterer, Markus; Wolf, Dietrich E.

    2017-06-01

    Densification of (semi-)conducting particle agglomerates with the help of an electrical current is much faster and more energy efficient than traditional thermal sintering or powder compression. Therefore, this method becomes more and more common among experimentalists, engineers, and in industry. The mechanisms at work at the particle scale are highly complex because of the mutual feedback between current and pore structure. This paper extends previous modelling approaches in order to study mixtures of particles of two different materials. In addition to the delivery of Joule heat throughout the sample, especially in current bottlenecks, thermoelectric effects must be taken into account. They lead to segregation or spatial correlations in the particle arrangement. Various model extensions are possible and will be discussed.

  6. Study on the isothermal forging process of MB26 magnesium alloy adaptor

    Directory of Open Access Journals (Sweden)

    Xu Wenchen

    2015-01-01

    Full Text Available The isothermal forging process is an effective method to manufacture complex-shaped components of hard-to-work materials, such as magnesium alloys. This study investigates the isothermal forging process of an MB26 magnesium alloy adaptor with three branches. The results show that two-step forging process is appropriate to form the adaptor forging, which not only improves the filling quality but also reduces the forging load compared with one-step forging process. Moreover, the flow line is distributed along the contour of the complex-shaped adaptor forging.

  7. Production of pure sintered alumina

    International Nuclear Information System (INIS)

    Rocha, J.C. da; Huebner, H.W.

    1982-01-01

    With the aim of optimizing the sintering parameters, the strength of a large number of alumina samples was determined which were produced under widely varying sintering conditions and with different amounts of MgO content. The strength as a function of sintering time or temperature was found to go through a maximum. With increasing time, this maximum is shifted to lower temperatures, and with decreasing temperature to longer times. Data pairs of sintering times and temperatures which yeld the strength maximum were determined. The value of the strength at the maximum remains unchanged. The strength is high (= 400 MN/m 2 , at a grain size of 3 um and a porosity of 2 per cent) and comparable to foreign aluminas produced for commercial purposes, or even higher. The increase in the sintering time from 1 h to 16 h permits a reduction of the sintering temperature from 1600 to 1450 0 C without losing strength. The practical importance of this fact for a production of sintered alumina on a large scale is emphasized. (Author) [pt

  8. The effect of forming stresses on the sintering of ultra-fine Ce0.9Gd0.1O2-δ powders

    DEFF Research Database (Denmark)

    Glasscock, Julie; Esposito, Vincenzo; Foghmoes, Søren Preben Vagn

    2013-01-01

    formed with techniques that apply low levels of stress had a particle arrangement which significantly enhanced sintering at low temperature, compared to those prepared by high stress techniques. The sample geometry, heat treatment for organic removal and the initial density of the green body had......The effect of particle and pore arrangement on sintering and densification of ultra-fine (∼130nm) Ce0.9Gd0.1O2-δ powder was evaluated. The common understanding that higher initial density of a ceramic network leads to a higher sintered density is not valid for fine powders, which have extremely...... good sinterability when there is a favourable particle packing. The effect of the applied stresses during forming (which produce different particle packing arrangements) was investigated by forging green bodies by different shaping techniques, including casting, and cold isostatic pressing. Samples...

  9. Applying "Spark Plasma Sintering" Technology to Enhance the Resistance to Contact Fatigue of Sintered Steel Based on Astaloy CRL

    Science.gov (United States)

    Rodziňák, D.; Čerňan, J.; Puchý, V.

    2017-12-01

    The article deals with the effect of porosity on the contact fatigue of sintered material type Astaloy CrL with 0.3 and 0.4% C. Sets of samples were used with densities beginning from the value of 7000 kg.m-3 to the value of almost 7859 kg.m-3 which represents almost zero porosity (compact material). It has been found out that the increase of compacting pressure applied simultaneously with temperature results in the reduction of porosity from the value of 9.10% to 0.0005% and increase in hardness from 145 to 193 HV10, depending on the carbon content. Logically there is also an increase in the fatigue life by the contact fatigue tests for the value of 50×106 cycles from the value of 900 MPa to 1150 MPa for samples with 0.3% of C and from 900 MPa to 1300 MPa for samples with 0.4% C. These investigations were also carried out in the past, but to achieve the reduction of porosity, different technonologies were used at each level such as double pressing, hot pressing, saturation, hot forging, etc. In this case, the single technology of "spark plasma sintering" making use of compacting at high temperatures is capable to continuously reduce porosity to zero.

  10. THEORETICAL ANALYSIS OF THE FORGING PROCESS FOR PRODUCING HOLLOW BALLS

    Directory of Open Access Journals (Sweden)

    Grzegorz Winiarski

    2013-06-01

    Full Text Available Hollow balls are used in the production of various machines and devices. The technology for producing hollow balls by metal forming technologies poses numerous difficulties connected with the forming of a hollow billet. The billet, which is usually in a form of a rod, is a subject to such processes as forging, helical rolling or cross-wedge rolling. The paper discusses a new method and conditions for producing a hollow ball. It was assumed that the ball would be produced in two forging operations: an initial forging operation and finishing forging operation. The presented results are based on the FEM numerical analysis conducted using DEFORM-3D. It was assumed that the billet material was made of AISI 304 stainless steel used to produce balls for ball valves. Both the shape progression during the forging process and variations in the forming force were analyzed. Based on the conducted analyses, it can be claimed that hollow balls can be produced using the proposed forging method.

  11. The sintering of nitrogen ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Hampshire, S.

    1986-01-01

    The mechanism of densification with oxide additives and the role of the ..cap alpha..-BETA phase transformation is investigated in a detailed kinetic study. Selected compositions in the Si-Al-O-N system are detailed, with and without additives. Although the work is mainly concerned with the identification of the mechanisms of sintering, some property measurements on a sintered BETA-sialon are reported and the feasibility of preparing pure ..cap alpha..-sialon phases is explored.

  12. Method of sintering ceramic materials

    Science.gov (United States)

    Holcombe, Cressie E.; Dykes, Norman L.

    1992-01-01

    A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density.

  13. Mechanical properties of the as-forged and the forged-and-milled steels for reactor pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Bong Sang; Yoon, Ji Hyun; Kim, Joo Hak; Oh, Yong Jun; Hong, Jun Hwa [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2001-04-01

    The mechanical properties of the as-forged and the forged and milled SA508-Gr.3 reactor pressure vessel steels were evaluated. The full Charpy impact curves obtained for four different locations in test materials. The various data including yield strengths, tensile strengths, elongations were obtained from the tensile strengths, elongations were obtained from the tensile test results for two locations in test materials. The detailed test results were integrated and analysed in this report. 6 refs., 7 figs., 5 tabs. (Author)

  14. Mannes of Forging and Perspectives of Knuckle Joint Presses Modernization

    Directory of Open Access Journals (Sweden)

    A. A. Antsifirov

    2014-01-01

    Full Text Available The article raises an issue to enhance technological forging capabilities on the known knuckle joint presses. It provides an illustrated overview of main design types of presses with crank-knuckle, toggle-knuckle, and knuckle joint mechanisms. The article also shows the advantages of the modernization way and improvement just of the active press equipment in terms of quality-to-price ratio, for example, as compared to the similar new foreign press equipment.It gives an overview of features, which provide forging processes owing to kinetic energy accumulated with the moving parts of the known designs of the knuckle joint presses depending on the drive actuating mechanism. Focused attention is drawn to forging on the knuckle joint presses for a time of contact with a work piece to be comparable with the duration of the work piece deformation process on hydraulic forging hammers. This allows us to forge thin-wall products with process automation compared to the forging hammers.Analysis of accumulating processes of kinetic energy by the moving parts of the knuckle joint presses has shown that presses driven by hydraulic cylinders or two screw hydraulic cylinder are the most optimal for technological operations as evidenced by references to domestic and foreign invention certificates and patents. The article presents disadvantages of forging on presses with hydraulic or pneumatic drive. It is a dependence of the deformation force, caused, mainly, by a force of the drive cylinder. The article gives linear movement rate quantities of press moving members depending on the drives of the actuating mechanism. Based on the above analysis of the features to manufacture work pieces on the knuckle joint presses, the article gives the rationale for the relevance of forging in a short period of time, provided that the moving parts of the press accumulate the required kinetic energy. This can be achieved only through modernization and improvement of forging

  15. Sintering diagrams of UO2

    International Nuclear Information System (INIS)

    Mohan, A.; Soni, N.C.; Moorthy, V.K.

    1979-01-01

    Ashby's method (see Acta Met., vol. 22, p. 275, 1974) of constructing sintering diagrams has been modified to obtain contribution diagrams directly from the computer. The interplay of sintering variables and mechanisms are studied and the factors that affect the participation of mechanisms in UO 2 are determined. By studying the physical properties, it emerges that the order of inaccuracies is small in most cases and do not affect the diagrams. On the other hand, even a 10% error in activation energies, which is quite plausible, would make a significant difference to the diagram. The main criticism of Ashby's approach is that the numerous properties and equations used, communicate their inaccuracies to the diagrams and make them unreliable. The present study has considerably reduced the number of factors that need to be refined to make the sintering diagrams more meaningful. (Auth.)

  16. Recycling of mill scale in sintering process

    Directory of Open Access Journals (Sweden)

    El-Hussiny N.A.

    2011-01-01

    Full Text Available This investigation deals with the effect of replacing some amount of Baharia high barite iron ore concentrate by mill scale waste which was characterized by high iron oxide content on the parameters of the sintering process., and investigation the effect of different amount of coke breeze added on sintering process parameters when using 5% mill scale waste with 95% iron ore concentrate. The results of this work show that, replacement of iron ore concentrate with mill scale increases the amount of ready made sinter, sinter strength and productivity of the sinter machine and productivity at blast furnace yard. Also, the increase of coke breeze leads to an increase the ready made sinter and productivity of the sintering machine at blast furnace yard. The productivity of the sintering machine after 5% decreased slightly due to the decrease of vertical velocity.

  17. Measurement of wisdom forging force using piezoelectric materials

    Directory of Open Access Journals (Sweden)

    Hsia Shao-Yi

    2017-01-01

    Full Text Available Aiming at forging machines for bolts and nuts with up to 61% market share, adding piezoelectric sensing units to the mold forging is discussed in this study. In the research process, it attempts to develop a sensing element with low cost, practicable limited space, acceptable performance stability, and real-time measurement of forging load by a five-stage forming system for special nuts matched with the theory of plastic forming, the CAD/CAE design and numerical analysis, and the installation of a piezoelectric unit. It aims to assist fastener businesses in the intelligentization, networking, and systemization of machines and further integrate into the Internet service manufacturing system to enhance the overall competitiveness of fastener industry.

  18. An empirical model for friction in cold forging

    DEFF Research Database (Denmark)

    Bay, Niels; Eriksen, Morten; Tan, Xincai

    2002-01-01

    With a system of simulative tribology tests for cold forging the friction stress for aluminum, steel and stainless steel provided with typical lubricants for cold forging has been determined for varying normal pressure, surface expansion, sliding length and tool/work piece interface temperature....... The results show, that friction is strongly influenced by normal pressure and tool/work piece interface temperature, whereas the other process parameters investigated show minor influence on friction. Based on the experimental results a mathematical model has been established for friction as a function...... of normal pressure and tool/work piece interface temperature. The model is verified by process testing measuring friction at varying reductions in cold forward rod extrusion. KEY WORDS: empirical friction model, cold forging, simulative friction tests....

  19. SUSCEPTOBILITY TO THERMAL FATIGUE OF CLOSED DIE HOT FORGING DIES

    Directory of Open Access Journals (Sweden)

    Frederico de Castro Magalhães

    2014-06-01

    Full Text Available Hot forging dies providing high productive performance reduce production costs. The lifetime of the dies is expressed by the number of forgings (production cycle produced before being rejected by the presence of a failure mechanism, associated with unacceptable dimensions and or geometry of the end product or even breakage of the dies. One of the failure mechanisms of hot forging dies is thermal fatigue, caused by cyclic heating and cooling. A subroutine, based on the work of Maim and Norstrom [1], was developed for the DEFORM 2D numerical software, using the finite element method, in order to predict die regions susceptible to thermal fatigue. The use of adequate coefficients for the description of the heat transfer phenomena allowed the validation of the proposed subroutine.

  20. Phosphorus containing sintered alloys (review)

    International Nuclear Information System (INIS)

    Muchnik, S.V.

    1984-01-01

    Phosphorus additives are considered for their effect on the properties of sintered alloys of different applications: structural, antifriction, friction, magnetic, hard, superhard, heavy etc. Data are presented on compositions and properties of phosphorus-containing materials produced by the powder metallurgy method. Phosphorus is shown to be an effective activator of sintering in some cases. When its concentration in the material is optimal it imparts the material such properties as strength, viscosity, hardness, wear resistance. Problems concerning powder metallurgy of amorphous phosphorus-containing alloys are reported

  1. Process model development for optimization of forged disk manufacturing processes

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, C.E.; Gunasekera, J.S. [Ohio Univ., Athens, OH (United States). Center for Advanced Materials Processing; Malas, J.C. [Wright Labs., Wright Patterson AFB, OH (United States). Materials Directorate

    1997-12-31

    This paper addresses the development of a system which will enable the optimization of an entire processing sequence for a forged part. Typically such a sequence may involve several stages and alternative routes of manufacturing a given part. It is important that such a system be optimized globally, (rather than locally, as is the current practice) in order to achieve improvements in affordability, producibility, and performance. This paper demonstrates the development of a simplified forging model, discussion techniques for searching and reducing a very large design space, and an objective function to evaluate the cost of a design sequence.

  2. Enhancement of mechanical properties of alloy steels on hot forging

    International Nuclear Information System (INIS)

    Radkevich, M.M.

    1993-01-01

    The paper present the results of an investigation into the effects of the basic parameters of high-temperature thermomechanical treatment (HTTMT) under hot forging. It is shown that forging in open dies of 45Kh, 20Kh13 and 08Kh18N10T steel blanks following the established HTTMT modes improves the ultimate strength by 46, 56 and 2% respectively, and yield limit - by 65, 66 and 14%, as compared with their production in compliance with factory modes, preserving the level of ductility and impact strength

  3. A numerical solution for a closed die forging process

    Directory of Open Access Journals (Sweden)

    Luca Dorin

    2017-01-01

    Full Text Available One of the manufacturing processes that can be permanent improved is plastic deformation of metallic materials, as incorporating reserves on the manufacture of products with reduced material and energy consumptions. This paper presents finite element analysis for a closed die forging process, showing the stresses, strains and temperature into deformed part and stresses in the working tools. The analysis of obtained results for different flash dimensions of the working tools has enabled optimization of the forging process studied. To be able to validate the numerical results obtained, experimental tests were conducted. The compared data series show a good agreement between the numerical and experimental data.

  4. Sintering of ultra high molecular weight polyethylene

    Indian Academy of Sciences (India)

    ... involves compaction of polymeric powder under pressure and sintering of the preforms at temperature above its melting point. In this study, we report our results on compaction and sintering behaviour of two grades of UHMWPE with reference to the powder morphology, sintering temperatures and strength development.

  5. Influence of alloying elements and density on aqueous corrosion behaviour of some sintered low alloy steels

    International Nuclear Information System (INIS)

    Kandavel, T.K.; Chandramouli, R.; Karthikeyan, P.

    2012-01-01

    Highlights: ► Corrosion of low alloy P/M steels under HCl acid pickling environment has been studied. ► Influence of density, strain and alloying elements on the rate of corrosion of the steels has been investigated. ► Residual porosity has significant effect on acid corrosion. ► Addition of the alloying elements Cu, Mo and Ti reduces the corrosion rate significantly. ► Carbide forming elements Mo and Ti improve further the resistance of the steels to aqueous corrosion. -- Abstract: Low alloy steels produced through powder metallurgy route of sintering followed by forging are promising candidate materials for high strength small components. Porosity in such steels poses a real challenge during acid pickling treatment, which is one of the processing steps during manufacturing. The present research work attempts to investigate the mechanism underlying the acid corrosion behaviour of some sintered low alloy steels under induced acid pickling conditions. Sintered-forged low alloy steel samples containing molybdenum (Mo), copper (Cu) and titanium (Ti) were subjected to aqueous corrosion attack by immersing the samples in 18% HCl (Hydrochloric acid) solution for 25 h. Sample weight loss and Fe (Iron) loss were estimated for the corroded samples. The morphology of the corroded surfaces was studied through metallography and scanning electron microscopy. Higher porosity alloys underwent enhanced corrosion rates. Both corrosion rate and iron loss are found to decrease linearly with reduction in porosity in all cases of the alloys. The alloying elements Mo, Ti and Cu, when added in combination, have played a complementary role in the reduction of corrosion rate by almost one order of magnitude compared to unalloyed steel. Presence of carbides of the carbide forming elements Mo and Ti played a positive role on the corrosion behaviour of the low alloy steels.

  6. Master Sintering Surface: A practical approach to its construction and utilization for Spark Plasma Sintering prediction

    Directory of Open Access Journals (Sweden)

    Pouchly V.

    2012-01-01

    Full Text Available The sintering is a complex thermally activated process, thus any prediction of sintering behaviour is very welcome not only for industrial purposes. Presented paper shows the possibility of densification prediction based on concept of Master Sintering Surface (MSS for pressure assisted Spark Plasma Sintering (SPS. User friendly software for evaluation of the MSS is presented. The concept was used for densification prediction of alumina ceramics sintered by SPS.

  7. Sintering additives for zirconia ceramics

    International Nuclear Information System (INIS)

    Wu, S.

    1986-01-01

    This book is an overview of sintering science and its application to zirconia materials including CaO, MgO, and Y/sub 2/O/sub 3/-CeO/sub 2/ doped materials. This book is a reference for first-time exposure to zirconia materials technology, particularly densification

  8. Sintering additives for zirconia ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wu, S.

    1986-01-01

    This book is an overview of sintering science and its application to zirconia materials including CaO, MgO, and Y/sub 2/O/sub 3/-CeO/sub 2/ doped materials. This book is a reference for first-time exposure to zirconia materials technology, particularly densification.

  9. 76 FR 30200 - Forging Machines; Extension of the Office of Management and Budget's (OMB) Approval of...

    Science.gov (United States)

    2011-05-24

    ...] Forging Machines; Extension of the Office of Management and Budget's (OMB) Approval of Information... extend OMB approval of the information collection requirements contained in the Forging Machines Standard... to reduce employees' risk of death or serious injury by ensuring that forging machines used by them...

  10. 75 FR 70689 - Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum-Greenwood Forge Division; Currently...

    Science.gov (United States)

    2010-11-18

    ... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-70,376] Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum- Greenwood Forge Division; Currently Known As Contech Forgings, LLC..., applicable to workers of Kaiser Aluminum Fabricated Products, LLC, Kaiser Aluminum-Greenwood Forge Division...

  11. Manufacturing technique and properties of integral type forgings for steam generator of nuclear power plant

    International Nuclear Information System (INIS)

    Suzuki, Komei; Sato, Ikuo; Murai, Etsuo

    1992-01-01

    The use of integral type steel forgings for the construction of pressure vessel enhances the structural integrity of components and makes the fabrication of components and the execution of in-service inspection (ISI) easier than those fabrication from plate and casting materials. Such steel forgings have been realized for steam generator (SG) for nuclear power plant as follows: (1) Forged shell ring: change from welding fabrication of formed plates to forging; (2) Forged conical shell ring: ditto; (3) Forged head integral with nozzles(s) : (i) Primary head: change from casting to forging; (ii) Secondary head: change from welding fabrication of formed plates to forging. These steel forgings have been realized by recent development in manufacturing technologies, such as steel making, forging processes and heat treatment which are vital to the quality of steel forgings. Some examples of recent typical high quality steel forgings developed by the Japan Steel Works, Ltd. (JSW) are introduced, and the main points of the manufacturing technique and the quality attained are also described. (author)

  12. Family Health and Financial Literacy--Forging the Connection

    Science.gov (United States)

    Braun, Bonnie; Kim, Jinhee; Anderson, Elaine A.

    2009-01-01

    Families are at-risk of or experiencing a diminished quality of living and life in current economic times and difficult decisions are required. Health and financial literacy are the basis for wise personal and public decision making. Family and consumer sciences (FCS) professionals can forge connections between health and financial literacy to…

  13. Forged Signature Distinction Using Convolutional Neural Network for Feature Extraction

    Directory of Open Access Journals (Sweden)

    Seungsoo Nam

    2018-01-01

    Full Text Available This paper proposes a dynamic verification scheme for finger-drawn signatures in smartphones. As a dynamic feature, the movement of a smartphone is recorded with accelerometer sensors in the smartphone, in addition to the moving coordinates of the signature. To extract high-level longitudinal and topological features, the proposed scheme uses a convolution neural network (CNN for feature extraction, and not as a conventional classifier. We assume that a CNN trained with forged signatures can extract effective features (called S-vector, which are common in forging activities such as hesitation and delay before drawing the complicated part. The proposed scheme also exploits an autoencoder (AE as a classifier, and the S-vector is used as the input vector to the AE. An AE has high accuracy for the one-class distinction problem such as signature verification, and is also greatly dependent on the accuracy of input data. S-vector is valuable as the input of AE, and, consequently, could lead to improved verification accuracy especially for distinguishing forged signatures. Compared to the previous work, i.e., the MLP-based finger-drawn signature verification scheme, the proposed scheme decreases the equal error rate by 13.7%, specifically, from 18.1% to 4.4%, for discriminating forged signatures.

  14. Fractography analysis of tool samples used for cold forging

    DEFF Research Database (Denmark)

    Dahl, K.V.

    2002-01-01

    Three fractured tool dies used for industrial cold forging have been investigated using light optical microscopy and scanning electron microscopy. Two of the specimens were produced using the traditional Böhler P/M steel grade s790, while the lastspecimen was a third generation P/M steel produced...... resistance towards abrasive wear compared with the traditional P/M steel....

  15. Small & medium Scale Casting and Forging Industry in India: an ...

    African Journals Online (AJOL)

    The ambient noise, temperature and dust exposure were assessed at different sections like; casting, moulding, forging, grinding, machining, and barreling. The results of the study revealed that 78% of the workers are not using PPE. Hence, the workers are exposed to high noise, temperature and dust. Occupational safety ...

  16. Numerical modelling of damage evolution in ingot forging

    DEFF Research Database (Denmark)

    Christiansen, Peter; Martins, Paulo A.F.; Bay, Niels Oluf

    2015-01-01

    The ingot forging process is numerically simulated applying both the Shima-Oyane porous plasticity model as a coupled damage model and the uncoupled normalized Cockcroft & Latham criterion. Four different cases including two different lower die angles (120º and 180º) and two different sizes of feed...

  17. Highlight: Forging the new Indonesia-Canada partnership | CRDI ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    15 avr. 2016 ... Canada's Centre for International Governance Innovation and Indonesia's Centre for Strategic and International Studies organized the Indonesia-Canada Bilateral Forum, Innovation and Change: Forging the New Indonesia-Canada Partnership. IDRC co-sponsored the meeting, held May 26-27, 2015.

  18. Fatigue in cold-forging dies: Tool life analysis

    DEFF Research Database (Denmark)

    Skov-Hansen, P.; Bay, Niels; Grønbæk, J.

    1999-01-01

    In the present investigation it is shown how the tool life of heavily loaded cold-forging dies can be predicted. Low-cycle fatigue and fatigue crack growth testing of the tool materials are used in combination with finite element modelling to obtain predictions of tool lives. In the models...... is reported. (C) 1999 Elsevier Science S.A. All rights reserved....

  19. Strain-enhanced sintering of iron powders

    Energy Technology Data Exchange (ETDEWEB)

    Amador, D.R.; Torralba, J.M. [Universidad Carlos III de Madrid, Departamento de Ciencias de Materiales e Ingenieria Metalurgica, Leganes, Madrid (Spain); Monge, M.A.; Pareja, R. [Universidad Carlos III de Madrid, Departamento de Fisica, Madrid (Spain)

    2005-02-01

    Sintering of ball-milled and un-milled Fe powders has been investigated using dilatometry, X-ray, density, and positron annihilation techniques. A considerable sintering enhancement is found in milled powders showing apparent activation energies that range between 0.44 and 0.80 eV/at. The positron annihilation results, combined with the evolution of the shrinkage rate with sintering temperature, indicate generation of lattice defects during the sintering process of milled and un-milled powders. The sintering enhancement is attributed to pipe diffusion along the core of moving dislocations in the presence of the vacancy excess produced by plastic deformation. Positron annihilation results do not reveal the presence of sintering-induced defects in un-milled powders sintered above 1200 K, the apparent activation energy being in good agreement with that for grain-boundary diffusion in {gamma}-Fe. (orig.)

  20. Influence of performance improvement of AP1000 nuclear island main equipment forging on manufacturing

    International Nuclear Information System (INIS)

    Liu Zhiying

    2013-01-01

    In order to comply with the 60-year design life of an AP1000 nuclear power station, higher strength and ductility requirements have been made on AP1000 nuclear island SG forgings than on CPR1000 nuclear island main equipment. In addition, bigger size of AP1000 nuclear island SG forgings increases the difficulty of manufacturing them. Insufficient recognition of these changes may cause unstable quality of forgings and possible quality problems in follow-up welding procedure. On the basis of comparison and analysis of AP1000 nuclear island SG forgings and CPR1000 nuclear island forgings, this thesis suggests clear directions for the actions we need to take. (author)

  1. Evaluation of the hot forging adjustment to the manufacture of forged parts: criteria of viability and optimization

    International Nuclear Information System (INIS)

    Arenas Reina, J. M.; Sebastian Perez, M. A.; Gonzalez Gaya, C.; Nunez Lopez, P. J.

    2000-01-01

    The design of industrial parts is a clear example of integrative effort that, with a focus of several disciplines, requires a detailed analysis of the different scientific and technological knowledge implied in its conception and development. Inside this performance context, the present work approaches the problem of the project of hot forging parts, proposing the use of criteria of viability and optimization that, based in technical and economical considerations, allow to valuate the adjusting degree of various alternative to the forge process, facilitating with it the selection of the most appropriate. Fixed these bases and with object of shortening times of answer analysis in an application corresponding to parts with revolution symmetry, a computerized system has been introduced that, taking as started data the design of the part, geometrically simulates the forge process, allowing to calculate the adaptation coefficients in those morphologies that are possible according to the criteria of viability criteria. This system also provides a graphic representation of machined part, the forged part and the finished stamp. (Author) 22 refs

  2. Sintered wire cesium dispenser photocathode

    Science.gov (United States)

    Montgomery, Eric J; Ives, R. Lawrence; Falce, Louis R

    2014-03-04

    A photoelectric cathode has a work function lowering material such as cesium placed into an enclosure which couples a thermal energy from a heater to the work function lowering material. The enclosure directs the work function lowering material in vapor form through a low diffusion layer, through a free space layer, and through a uniform porosity layer, one side of which also forms a photoelectric cathode surface. The low diffusion layer may be formed from sintered powdered metal, such as tungsten, and the uniform porosity layer may be formed from wires which are sintered together to form pores between the wires which are continuous from the a back surface to a front surface which is also the photoelectric surface.

  3. Nuclear tracks in sinterized gemstones

    International Nuclear Information System (INIS)

    Espinosa, G.; Rodriguez, L.V.; Golzarri, J.I.; Castano, V.M.

    1993-01-01

    The responses of sinterized gemstones to alpha particles attempt analyzed with the objective of finding new materials for SSNTD, and also to understand their interaction with radiation and the formation of tracks. In this work we present the results of the characterization of these materials as SSNTD. The micro structural changes observed by electron microscopy. The preparation, etching solution concentration, etching time and effects of temperature are discussed. (Author)

  4. Microwave sintering of ceramic materials

    Science.gov (United States)

    Karayannis, V. G.

    2016-11-01

    In the present study, the potential of microwave irradiation as an innovative energy- efficient alternative to conventional heating technologies in ceramic manufacturing is reviewed, addressing the advantages/disadvantages, while also commenting on future applications of possible commercial interest. Ceramic materials have been extensively studied and used due to several advantages they exhibit. Sintering ceramics using microwave radiation, a novel technology widely employed in various fields, can be an efficient, economic and environmentally-friendlier approach, to improve the consolidation efficiency and reduce the processing cycle-time, in order to attain substantial energy and cost savings. Microwave sintering provides efficient internal heating, as energy is supplied directly and penetrates the material. Since energy transfer occurs at a molecular level, heat is generated throughout the material, thus avoiding significant temperature gradients between the surface and the interior, which are frequently encountered at high heating rates upon conventional sintering. Thus, rapid, volumetric and uniform heating of various raw materials and secondary resources for ceramic production is possible, with limited grain coarsening, leading to accelerated densification, and uniform and fine-grained microstructures, with enhanced mechanical performance. This is particularly important for manufacturing large-size ceramic products of quality, and also for specialty ceramic materials such as bioceramics and electroceramics. Critical parameters for the process optimization, including the electromagnetic field distribution, microwave-material interaction, heat transfer mechanisms and material transformations, should be taken into consideration.

  5. Titanium Powder Sintering in a Graphite Furnace and Mechanical Properties of Sintered Parts

    OpenAIRE

    Changzhou Yu; Peng Cao; Mark Ian Jones

    2017-01-01

    Recent accreditation of titanium powder products for commercial aircraft applications marks a milestone in titanium powder metallurgy. Currently, powder metallurgical titanium production primarily relies on vacuum sintering. This work reported on the feasibility of powder sintering in a non-vacuum furnace and the tensile properties of the as-sintered Ti. Specifically, we investigated atmospheric sintering of commercially pure (C.P.) titanium in a graphite furnace backfilled with argon and stu...

  6. Production of sintered alumina from powder; optimization of the sinterized parameters for the maximum mechanical resistence

    International Nuclear Information System (INIS)

    Rocha, J.C. da.

    1981-02-01

    Pure, sinterized alumina and the optimization of the parameters of sinterization in order to obtain the highest mechanical resistence are discussed. Test materials are sinterized from a fine powder of pure alumina (Al 2 O 3 ), α phase, at different temperatures and times, in air. The microstructures are analysed concerning porosity and grain size. Depending on the temperature or the time of sinterization, there is a maximum for the mechanical resistence. (A.R.H.) [pt

  7. Hot forging of roll-cast high aluminum content magnesium alloys

    Science.gov (United States)

    Kishi, Tomohiro; Watari, Hisaki; Suzuki, Mayumi; Haga, Toshio

    2017-10-01

    This paper reports on hot forging of high aluminum content magnesium alloy sheets manufactured using horizontal twin-roll casting. AZ111 and AZ131 were applied for twin-roll casting, and a hot-forging test was performed to manufacture high-strength magnesium alloy components economically. For twin-roll casting, the casting conditions of a thick sheet for hot forging were investigated. It was found that twin-roll casting of a 10mm-thick magnesium alloy sheet was possible at a roll speed of 2.5m/min. The grain size of the cast strip was 50 to 70µm. In the hot-forging test, blank material was obtained from as-cast strip. A servo press machine with a servo die cushion was used to investigate appropriate forging conditions (e.g., temperature, forging load, and back pressure) for twin-roll casts (TRCs) AZ111 and AZ131. It was determined that high aluminum content magnesium alloy sheets manufactured using twin-roll casting could be forged with a forging load of 150t and a back pressure of 3t at 420 to 430°C. Applying back pressure during hot forging effectively forged a pin-shaped product.

  8. Increasing of the lifetime of large forging dies by repairwelding

    Science.gov (United States)

    Duchek, M.; Koukolikova, M.; Kotous, J.; Majer, M.

    2018-02-01

    Repair welding is often used for rebuilding discarded or failed forging dies. It saves the cost of new tools. Increased useful life of repaired dies is another motivation for repair welding. This article focuses on the development of new filler materials for this purpose. The main goal was to prolong the life of tools of DIN 1.2714 material. Filler wires of two chemistries were made and several samples were experimentally welded. Metallographic and tribological analyses were carried out.

  9. A Probabilistic Analysis of the Nxt Forging Algorithm

    Directory of Open Access Journals (Sweden)

    Serguei Popov

    2016-12-01

    Full Text Available We discuss the forging algorithm of Nxt from a probabilistic point of view, and obtain explicit formulas and estimates for several important quantities, such as the probability that an account generates a block, the length of the longest sequence of consecutive blocks generated by one account, and the probability that one concurrent blockchain wins over an- other one. Also, we discuss some attack vectors related to splitting an account into many smaller ones.

  10. Alternative sintering methods compared to conventional thermal sintering for inkjet printed silver nanoparticle ink

    NARCIS (Netherlands)

    Niittynen, J.; Abbel, R.; Mäntysalo, M.; Perelaer, J.; Schubert, U.S.; Lupo, D.

    2014-01-01

    In this contribution several alternative sintering methods are compared to traditional thermal sintering as high temperature and long process time of thermal sintering are increasing the costs of inkjet-printing and preventing the use of this technology in large scale manufacturing. Alternative

  11. Protocol for Ultralow-Temperature Ceramic Sintering: An Integration of Nanotechnology and the Cold Sintering Process.

    Science.gov (United States)

    Guo, Hanzheng; Baker, Amanda; Guo, Jing; Randall, Clive A

    2016-11-22

    The sintering process is an essential step in taking particulate materials into dense ceramic materials. Although a number of sintering techniques have emerged over the past few years, the sintering process is still performed at high temperatures. Here we establish a protocol to achieve dense ceramic solids at extremely low temperatures (sustainable manufacturing practices.

  12. The effect of the ceramic core initial phase composition on the Ag-sheathed Bi-2223 tapes critical properties

    International Nuclear Information System (INIS)

    Nikulin, A.D.; Shikov, A.K.; Khlebova, N.E.; Antipova, E.V.; Dontsova, E.V.; Kazakov, E.G.; Medvedev, M.I.; Kozlenkova, N.I.; Shishov, V.N.; Akimov, I.I.

    1993-01-01

    Ag - sheathed superconducting tapes were fabricated using ''powder-in-tube'' method with powders of Bi 1.6 Pb 0.4 Sr 2 Ca 2 Cu 3.2 O x chemical composition prepared by the ''freeze-drying'' tecnique and taken as a core materials. The effect of ceramic core initial phase composition: the mixture of oxide non-superconducting phases - OP (typeI) and 50% OP + 50% OP ''2212''- phase (type II) on the critical current density was investigated as well as the ''annealing - cold pressing'' parameters. Multifilamentary superconducting tapes and the pancake coils were fabricated. (orig.)

  13. The FORGE (Fate Of Repository Gases) pan European project

    International Nuclear Information System (INIS)

    Shaw, Richard

    2010-01-01

    Document available in extended abstract form only. Full text of publication follows: The multiple barrier concept is the cornerstone of all proposed schemes for underground disposal of radioactive wastes. The concept invokes a series of barriers, both engineered and natural, between the waste and the surface. Achieving this concept is the primary objective of all disposal programmes, from site appraisal and characterisation to repository design and construction. However, the performance of the repository as a whole (waste, buffer, engineering disturbed zone, host rock), and in particular its gas transport properties, are still poorly understood. Issues still to be adequately examined that relate to understanding basic processes include: dilational versus visco-capillary flow mechanisms; long-term integrity of seals, in particular gas flow along contacts; role of the EDZ as a conduit for preferential flow; laboratory to field up-scaling. Understanding gas generation and migration is thus vital in the quantitative assessment of repositories and is the focus of the research in this proposal for an integrated, multidisciplinary project. The FORGE project is a pan-European project with links to international radioactive waste management organisations, regulators and academia, specifically designed to tackle the key research issues associated with the generation and movement of repository gasses with partners from 24 organisations in 12 European countries. It is supported by funding under the European Commission FP7 Euratom programme and runs from 2009 to 2013. Of particular importance are the long-term performance of bentonite buffers, plastic clays, indurated mud-rocks and crystalline formations. Further experimental data are required to reduce uncertainty relating to the quantitative treatment of gas in performance assessment. FORGE will address these issues through a series of laboratory and field-scale experiments, including the development of new methods for up

  14. Effect of Laser Preheating AISI 4140 Specimens for Micro-Forging

    Directory of Open Access Journals (Sweden)

    Jung C.

    2017-06-01

    Full Text Available Many high performance and permanent service parts require suitable material characteristics-high fatigue strength is one of the most important characteristics. For this reason, surface treatment processes are essential to increase the material performance and avoid the use of costly ineffective material. There exist various surface treatment processes for various applications. Each process has advantages and disadvantages and hybridization can solve various problems. The micro-forging process delivers a controlled and uniform surface hardness, but the depth of the forged surface is limited. On the other hand, laser heat treatment can increase the hardness drastically, but the surface may become brittle, which reduces the fatigue life. Laser-assisted micro-forging is a novel hybrid process of laser heat treatment and micro-forging that has the potential to increase the forging depth and relax the stress caused by the high temperature of the forging process.

  15. Investigation of the influence of hybrid layers on the life time of hot forging dies

    Directory of Open Access Journals (Sweden)

    S. Legutko

    2013-04-01

    Full Text Available The paper deals with the issues related in the process of drop forging with special attention paid to the durability of forging tools. It presents the results of industrial investigation of the influence of hybrid layers on hot forging dies. The effectiveness of hybrid layers type nitrided layer/PVD coating applied for extending the life of forging tools whose working surfaces are exposed to such complex exploitation conditions as, among others, cyclically varying high thermal and mechanical loads, as well as intensive abrasion at raised temperature. The examination has been performed on a set of forging tools made of Unimax steel and intended for forging steel rings of gear box synchronizer in the factory FAS in Swarzedz (Poland.

  16. Research on Integrated Casting and Forging Process of Aluminum Automobile Wheel

    Directory of Open Access Journals (Sweden)

    Qi Zhang

    2014-07-01

    Full Text Available Integrated casting and forging process (ICFP is a new manufacturing method combining the advantages of both casting and forging. Aluminum structure parts, such as aluminum alloy automobile wheel, with complex shape and excellent mechanical properties can be produced by this process. The effects of different process parameters on the ICFP of the automobile wheel were simulated by Forge software. Microstructure of forging region and the nonforging region were studied by experiment. The results show that die temperature, static pressure of the injection piston, forging speed, and material flow have significant influences on the process. Compared with nonforging region, the microstructure of forging region becomes finer, more uniform, and denser. Meanwhile, the casting defects can be removed and mechanical properties improved.

  17. Development of Profile Forging for Channel Head of Ap/Acp Steam Generator

    Science.gov (United States)

    Bao-zhong, Wang; Ying, Liu; Yi, Guo; Kai-quan, Liu; De-li, Zhao; Ling-ling, Zhao

    The AP/CAP Steam Generator has the most complex structure in current nuclear power plant forgings. In order to improve material utilization and nozzle Properties, China First Heavy Industries (CFHI) have carried out the study on profile and blocker-type forging for Channel Head. The numerical and physical Simulations verify that the channel head can be forged step by step in profiling dies with 100 150MN hydraulic press. The achievement has been applied firstly in the AP1000 project of Xian Ning 1#. On this basis, the optimizations of forging process and die structure have been completed. Through process optimizations above, the nozzles of different shapes have obtained uniform deformation and the full-size channel head forging (Including main forging and samples) of CAP1400 steam generator has been manufactured successfully. And the mechanical properties indicate that the toughness has been improved obviously and the gas content has been reduced effectively in nozzle regions.

  18. Master sintering curves of two different alumina powder compacts

    Directory of Open Access Journals (Sweden)

    Vaclav Pouchly

    2009-12-01

    Full Text Available Concept of Master Sintering Curve is a strong tool for optimizing sintering schedule. The sintering behaviour can be predicted, and sintering activation energy can be calculated with the help of few dilatometric measurements. In this paper an automatic procedure was used to calculate Master Sintering Curves of two different alumina compacts. The sintering activation energies were determined as 640 kJ/mol for alumina with particle size of 240 nm, respective 770 kJ/mol for alumina with particle size of 110 nm. The possibility to predict sintering behaviour with the help of Master Sintering Curve was verified.

  19. PACVD Duplex Coating for Hot Forging of High Strength Steels for Automotive Applications

    OpenAIRE

    LESKOVŠEK, Vojteh; JENKO, Monika; PODGORNIK, Bojan

    2011-01-01

    The tribological load is the load on forging tools resulting from the relative motions between the plastically deformed workpiece and the die. In comparison to many other forming processes hot die forging has an especially disadvantageous tribological system. The advantages of the application of hard coatings, which are well known for cutting tools, are to a much lesser extent explored for casting, extrusion, moulding and forging tools. Increasing the lifetime of these tools...

  20. Controlled austempering of hammer forgings aimed at pseudo normalized microstructure directly after deformation

    Directory of Open Access Journals (Sweden)

    P. Skubisz

    2017-01-01

    Full Text Available The study concerns cost-effective realization of controlled thermomechanical processing (CTMP of medium-carbon and HSLA steel aimed at producing microstructure and properties equivalent to normalized condition directly after forging. The results of theoretical and physical modeling of hot forging with subsequent heat treating adopted for industrial realization in continuous manner were verified in semi-industrial conditions of a forge plant.

  1. Sintering characteristics of nano-ceramic coatings

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Popma, R.

    2003-01-01

    This paper concentrates on sintering characteristics of nano-sized ceramic SiO2 particles. The sintering process is studied as a function of temperature using a conventional furnace and using a laser beam. The underlying idea is to combine the nanoceramic sol-gel concept with inkjet technology and

  2. Mechanical characteristics of microwave sintered silicon carbide

    Indian Academy of Sciences (India)

    In firing of products by conventionally sintered process, SiC grain gets oxidized producing SiO2 (∼ 32 wt%) and deteriorates the quality of the product substantially. Partially sintered silicon carbide by such a method is a useful material for a varieties of applications ranging from kiln furniture to membrane material.

  3. Kinetic analysis of boron carbide sintering

    International Nuclear Information System (INIS)

    Borchert, W.; Kerler, A.R.

    1975-01-01

    The kinetics of the sintering of boron carbide were investigated by shrinkage measurements with a high-temperature dilatometer under argon atmosphere in dependence on temperature, grain size, and pressure. The activation energies and the reaction mechanisms of the different stages of sintering were determined. (orig.) [de

  4. Sintering of ultra high molecular weight polyethylene

    Indian Academy of Sciences (India)

    Abstract. Ultra high molecular weight polyethylene (UHMWPE) is a high performance polymer having low coefficient of friction, good abrasion resistance, good chemical ... In this study, we report our results on compaction and sintering behaviour of two grades of UHMWPE with reference to the powder morphology, sintering ...

  5. Sintered-to-size FBR fuel

    International Nuclear Information System (INIS)

    Rasmussen, D.E.; Schaus, P.S.

    1984-04-01

    Fabrication of sintered-to-size PuO 2 -UO 2 fuel pellets was completed for testing of proposed FBR product specifications. Approximately 6000 pellets were fabricated to two nominal diameters and two densities by cold pressing and sintering to size. Process control and correlation between test and production batches are discussed

  6. Sintering of zirconia in high-pressure

    International Nuclear Information System (INIS)

    Kunrath, A.O.; Strohaecker, T.R.; Pereira, A.S.; Jornada, J.A.H. da; Piermarini, G.J.

    1989-01-01

    A systematic study about the sintering of zirconia hyperfines powders in high-pressure is presented. The differents conditions effect of sintering in microstructure and in hardness and tenacity properties of zirconia samples with a very fine grain is also studied. (C.G.C.) [pt

  7. Modeling the microstructural evolution during constrained sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Frandsen, Henrik Lund; Tikare, V.

    A numerical model able to simulate solid state constrained sintering of a powder compact is presented. The model couples an existing kinetic Monte Carlo (kMC) model for free sintering with a finite element (FE) method for calculating stresses on a microstructural level. The microstructural respon...

  8. Modeling the Microstructural Evolution During Constrained Sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Frandsen, Henrik Lund; Pryds, Nini

    2015-01-01

    A numerical model able to simulate solid-state constrained sintering is presented. The model couples an existing kinetic Monte Carlo model for free sintering with a finite element model (FEM) for calculating stresses on a microstructural level. The microstructural response to the local stress as ...

  9. Mechanical characteristics of microwave sintered silicon carbide

    Indian Academy of Sciences (India)

    Unknown

    Central Glass and Ceramic Research Institute, Kolkata 700 032, India. Abstract. The present work deals with the sintering of ... recently become an attractive area of research and deve- lopment. The major advantages of ... without the usage of sintering aids (Lee and Case 1999;. Goldstein et al 1999). Several studies have ...

  10. THE POLARIZING EFFECTS IN SINTERED KAOLIN

    African Journals Online (AJOL)

    compacted and sintered density of the ceramic have been studied, and a density — pressure relationship for before- and after-sintering conditions obtained. INTRODUCTION. Ceramics have been known to mankind for thousands of years, and have been used in construction materials. In many applications, ceramics have.

  11. The Influence of Sintering Temperature of Reactive Sintered (Ti, MoC-Ni Cermets

    Directory of Open Access Journals (Sweden)

    Marek Jõeleht

    2015-09-01

    Full Text Available Titanium-molybdenum carbide nickel cermets ((Ti, MoC-Ni were produced using high energy milling and reactive sintering process. Compared to conventional TiC-NiMo cermet sintering the parameters for reactive sintered cermets vary since additional processes are present such as carbide synthesis. Therefore, it is essential to acquire information about the suitable sintering regime for reactive sintered cermets. One of the key parameters is the final sintering temperature when the liquid binder Ni forms the final matrix and vacancies inside the material are removed. The influence of the final sintering temperature is analyzed by scanning electron microscopy. Mechanical properties of the material are characterized by transverse rupture strength, hardness and fracture toughness.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7179

  12. Sintered ceramics having controlled density and porosity

    International Nuclear Information System (INIS)

    Brassfield, H.C.; DeHollander, W.R.; Nivas, Y.

    1980-01-01

    A new method was developed for sintering ceramic uranium dioxide powders, in which ammonium oxalate is admixed with the powder prior to being pressed into a cylindrical green body, so that the end-point density of the final nuclear-reactor fuel product can be controlled. When the green body is heated, the ammonium oxalate decomposes and leaves discrete porosity in the sintered body, which corresponds to the ammonium oxalate regions in the green body. Thus the end-point density of the sintered body is a function of the amount of ammonium oxalate added. The final density of the sintered product is about 90-97% of the theoretical. The addition of ammonium oxalate also allows control of the pore size and distribution throughout the fuel. The process leaves substantially no impurities in the sintered strucuture. (DN)

  13. Residual Stresses in 21-6-9 Stainless Steel Warm Forgings

    Energy Technology Data Exchange (ETDEWEB)

    Everhart, Wesley A.; Lee, Jordan D.; Broecker, Daniel J.; Bartow, John P.; McQueen, Jamie M.; Switzner, Nathan T.; Neidt, Tod M.; Sisneros, Thomas A.; Brown, Donald W.

    2012-11-14

    Forging residual stresses are detrimental to the production and performance of derived machined parts due to machining distortions, corrosion drivers and fatigue crack drivers. Residual strains in a 21-6-9 stainless steel warm High Energy Rate Forging (HERF) were measured via neutron diffraction. The finite element analysis (FEA) method was used to predict the residual stresses that occur during forging and water quenching. The experimentally measured residual strains were used to calibrate simulations of the three-dimensional residual stress state of the forging. ABAQUS simulation tools predicted residual strains that tend to match with experimental results when varying yield strength is considered.

  14. Physical modeling and numerical simulation of V-die forging ingot with central void

    DEFF Research Database (Denmark)

    Christiansen, Peter; Hattel, Jesper Henri; Bay, Niels

    2014-01-01

    of the lower V-die angle on porosity closure and forging load requirements of large cast ingots. Results show that a lower V-die angle of 120 provides the best closure of centerline porosity without demanding the highest forging loads or developing unreasonably asymmetric shapes that may create difficulties......Numerical simulation and physical modeling performed on small-scale ingots made from pure lead, having a hole drilled through their centerline to mimic porosity, are utilized to characterize the deformation mechanics of a single open die forging compression stage and to identify the influence...... in multi-stage open die forging procedures....

  15. Titanium Powder Sintering in a Graphite Furnace and Mechanical Properties of Sintered Parts

    Directory of Open Access Journals (Sweden)

    Changzhou Yu

    2017-02-01

    Full Text Available Recent accreditation of titanium powder products for commercial aircraft applications marks a milestone in titanium powder metallurgy. Currently, powder metallurgical titanium production primarily relies on vacuum sintering. This work reported on the feasibility of powder sintering in a non-vacuum furnace and the tensile properties of the as-sintered Ti. Specifically, we investigated atmospheric sintering of commercially pure (C.P. titanium in a graphite furnace backfilled with argon and studied the effects of common contaminants (C, O, N on sintering densification of titanium. It is found that on the surface of the as-sintered titanium, a severely contaminated porous scale was formed and identified as titanium oxycarbonitride. Despite the porous surface, the sintered density in the sample interiors increased with increasing sintering temperature and holding time. Tensile specimens cut from different positions within a large sintered cylinder reveal different tensile properties, strongly dependent on the impurity level mainly carbon and oxygen. Depending on where the specimen is taken from the sintered compact, ultimate tensile strength varied from 300 to 580 MPa. An average tensile elongation of 5% to 7% was observed. Largely depending on the interstitial contents, the fracture modes from typical brittle intergranular fracture to typical ductile fracture.

  16. Modeling Cavitation in ICE Pistons Made with Isothermal Forging

    Directory of Open Access Journals (Sweden)

    V.V. Astanin

    2014-07-01

    Full Text Available Possible causes for cavitations in parts made with an Al-Si eutectic alloy AK12D (AlSi12 were explored with mathematical and physical modeling with involved acoustic emission. Pores were formed from micro-cracks, which appear during the early stages of a deformation process, with the help of micro-stresses appearing at phase boundaries (Al/Si interface due to thermal expansion. At the design stage of isothermal forgings of such products it is recommended to provide a scheme of the deformed shape, which is under uniform compression, to compensate for the inter-phase stresses.

  17. Manufacturing involving forging of multiple objects in contact

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Zhang, W.; Martins, P.A.F.

    Finite element modeling of multi-object manufacturing processes is presented with supporting experiments. The underlying finite element implementation is based on the flow formulation and further coupled with thermal and electrical models to accomplish electro-thermo-mechanical simulation. All...... and dissimilar materials. While being plastically deformed against each other under increasing forging load, the parts dynamically develop their mutual contact interfaces. Comparisons of the final geometry as well as force-displacement curves are evaluated. The potential of simulated applications are discussed...

  18. A new Friction and Lubrication Test for Cold Forging

    DEFF Research Database (Denmark)

    Bay, Niels; Wibom, Ole; Aalborg Nielsen, J

    1995-01-01

    This paper presents a new friction and lubrication test for cold forging. The test allows controlled variation of the surface expansion in the range 0-2000%, the tool temperature in the range 20-270°C and the sliding length between 0 and infinite. Friction is decreasing with increasing temperature...... in the range 30-150°C. Above this temperature range friction increases. As regards lubricant performance Lubrication Limit Curves (LLC) are plotted in a sliding length-surface enlargement diagram with the tool temperature as a parameter. Larger tool temperature implies lower acceptable surface expansion...

  19. Environmentally Benign Lubricant Systems For Cold, Warm And Hot Forging

    DEFF Research Database (Denmark)

    Bay, Niels

    2010-01-01

    The growing awareness of environmental issues and the requirements to establish solutions diminishing the impact on working environment as well as external environment has initiated ever increasing efforts to develop new, environmentally benign tribological systems for metal forming. The present...... paper gives an overview of these efforts substituting environmentally hazardous lubricants in cold, warm and hot forging. The paper is an extract of the keynote paper [3] written by the author together with eight co-authors referring to collected papers and other information from more than 30 different...

  20. Thermodynamics and mechanisms of sintering

    International Nuclear Information System (INIS)

    Pask, J.A.

    1978-10-01

    A phenomenological overview and exploration of the thermodynamic and geometric factors play a role in the process of densification of model compact systems consisting of crystalline spheres of uniform size in regular and irregular packing that form grain boundaries at every contact point. A further assumption is the presence of isotropic surface and grain boundary energies. Although such systems are unrealistic in comparison with normal powder compacts, their potential sintering behavior can be analyzed and provided with a limiting set of behavior conditions which can be looked upon as one boundary condition. This approach is logically realistic since it is easier to understand and provide a basis for understanding the more complex real powder systems

  1. Melting and Sintering of Ashes

    DEFF Research Database (Denmark)

    Hansen, Lone Aslaug

    1997-01-01

    , the biggest deviations being found for salt rich (i.e. straw derived) ashes.A simple model assuming proportionality between fly ash fusion and deposit formation was found to be capable of ranking deposition rates for the different straw derived fly ashes, whereas for the fly ashes from coal/straw co......-firing, the model only had a qualitative agreement with the measured ash deposit formation rates.Sintering measurements were carried out by means of compression strength testing of ash pellets. This method showed to not be applicable for the salt rich fly ash derived from straw combustion. For the fly ashes...... have been employed in a simple model for prediction of ash deposit formation, the results of which have been compared to ash deposition formation rates measured at the respective boilers.The ash fusion results were found to directly reflect the ash compositional data:a) Fly ashes and deposits from...

  2. Science of sintering and its future

    International Nuclear Information System (INIS)

    Ristic, M.M.

    1975-01-01

    Some new books published by M.Yu. Baljshin, V.A. Ivensen, V.V. Skorohod and others are characterized by the wish to give a complete approach to the problems of sintering theory. Bearing just this in mind while writing the book ''An Essay on the Generalization of Sintering Theory'' (G.V.Samsonov, M.M. Ristic with the collaborators) an idea was born: to ask the most eminent scientists in this field to present their own opinions on the theme ''The Science of Sintering and Modern Views on its Future''. There were formed 18 questions, given in the appendix to be answered. The received answers were presented in 10 chapters of this book. The fourth part of the book consists of papers of eminent scientists engaged in the field of sintering science (some of which were published here for the first time). This material is published in the book with the consent of the authors and these original contributions provide a more profound knowledge of sintering. The initial idea, that the book should have a monograph character and in which the answers would serve as some data on the latest notions of the science of sintering, was somewhat changed since the original opinions of individual scientists are given in the book and these, are sometimes very contradictory. This, in fact, gives the book a special charm because the unsolved problems in the science of sintering are most evidently stressed in this way

  3. Trial production of titanium orthodontic brackets fabricated by metal injection molding (MIM) with sintering.

    Science.gov (United States)

    Deguchi, T; Ito, M; Obata, A; Koh, Y; Yamagishi, T; Oshida, Y

    1996-07-01

    Safety and esthetics are two indispensable factors to consider when fabricating orthodontic brackets. However, these factors are not easily achieved when conventional techniques (including forging and casting) are used in the mass production of titanium brackets, albeit the brackets exhibit excellent biocompatibility. In the present study, orthodontic brackets were manufactured by metal powder injection molding with sintering. Brackets with three different base designs were made and subjected to compression shear tests for evaluation of their bonding strength to enamel substrate. The shapes given to the dimple of the base were spherical, oval, and grooved. The maximum shear forces for each type were 11.1 kgf, 7.6 kgf, and 18.5 kgf, respectively. The bonding strengths of the titanium bracket were equivalent to those obtained with conventional stainless steel brackets. Moreover, uniform distribution of Vickers hardness values (average, 240 +/- 40 Hv) measured at three locations indicated that the titanium bracket was uniformly sintered. Accordingly, titanium brackets thus fabricated exhibit a potential for clinical application.

  4. Immobilization of Uranium Silicides in Sintered Glass

    International Nuclear Information System (INIS)

    Mateos, P.; Russo, D.O.; Heredia, A.D.; Sanfilippo, M.

    2003-01-01

    High activity nuclear spent fuels vitrification by fusion is a well known technology which has industrial scale in France, England, Japan, EEUU. Borosilicates glasses are used in this process.Sintered glasses are an alternative to the immobilization task in which there is also a wide experience around the world.The available technics are: cold pressing and sintering , hot-pressing and hot isostatic pressing.This work compares Borosilicates and Iron silicates sintered glasses behaviour when different ammounts of nuclear simulated waste is added

  5. Solidification of HLLW into sintered ceramics

    International Nuclear Information System (INIS)

    O-Oka, K.; Ohta, T.; Masuda, S.; Tsunoda, N.

    1979-01-01

    Simulated HLLW from the PNC reprocessing plant at Tokai was solidified into sintered ceramics by normal sintering or hot-pressing with addition of some oxides. Among various ceramic products obtained so far, the most preferable was nepheline-type sintered solids formed with addition of SiO 2 and Al 2 O 3 to the simulated waste calcine. The solid shows advantageous properties in leach rate and mechanical strength, which suggest that the ceramic solids were prepared with additions of ZrO 2 or MnO 2 , and some of them showed good characteristics

  6. Effect of sintering temperature and heating mode on consolidation of ...

    Indian Academy of Sciences (India)

    Microwave sintering was performed in 2.45 GHz multimode microwave furnace at temperatures ranging from 570–630 °C. Microwave sintering at a heating rate of as high as 22°C/min resulted in ∼55% reduction of processing time as compared to conventional sintering. A lower sintered density observed in the case of ...

  7. Sintering of nano crystalline o silicon carbide doping with

    Indian Academy of Sciences (India)

    Sinterable silicon carbide powders were prepared by attrition milling and chemical processing of an acheson type -SiC. Pressureless sintering of these powders was achieved by addition of aluminium nitride together with carbon. Nearly 99% sintered density was obtained. The mechanism of sintering was studied by ...

  8. 40 CFR 467.40 - Applicability; description of the forging subcategory.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Applicability; description of the forging subcategory. 467.40 Section 467.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 467.40 Applicability; description of the forging subcategory. This subpart applies to discharges of...

  9. Research on Double CCD Dimensional Metrology Applying in Large Forge Piece

    International Nuclear Information System (INIS)

    Hu, C H; Xiong, Z

    2006-01-01

    As development of computer vision, stereoscopic vision sensors have been used more and more widely, and double CCD vision sensor with its simplicity of operator, highaccuracy and high-efficiency has been used in many spheres. It can be used in dimensional metrology of large forge piece, which greatly improves the efficiency and accuracy of large forge piece measurement

  10. MM 99.58 Physical modelling of Hammerhead forging, Vertical and Lateral load history

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Eriksen, Morten; Wanheim, Tarras

    1999-01-01

    The present report presents a laboratory setup with hammerhead forging, where the vertical and lateral force history is obtained under different process conditions......The present report presents a laboratory setup with hammerhead forging, where the vertical and lateral force history is obtained under different process conditions...

  11. CoPEH-Can forges links and places students in the forefront | CRDI ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    La CPE-Can forge des liens et place les étudiants au premier rang. Chercheuses et chercheurs principaux, Communauté de pratique en écosanté-Canada (CP. Voir davantageLa CPE-Can forge des liens et place les étudiants au premier rang ...

  12. Improved compaction of ZnO nano-powder triggered by the presence of acetate and its effect on sintering

    International Nuclear Information System (INIS)

    Dargatz, Benjamin; Gonzalez-Julian, Jesus; Guillon, Olivier

    2015-01-01

    The retention of nanocrystallinity in dense ceramic materials is still a challenge, even with the application of external pressure during sintering. The compaction behavior of high purity and acetate enriched zinc oxide (ZnO) nano-powders was investigated. It was found that acetate in combination with water plays a key role during the compaction into green bodies at moderate temperatures. Application of constant pressure resulted in a homogeneous green body with superior packing density (86% of theoretical value) at moderate temperature (85 °C) in the presence of water. In contrast, no improvement in density could be achieved if pure ZnO powder was used. This compaction behavior offers superior packing of the particles, resulting in a high relative density of the consolidated compact with negligible coarsening. Dissolution accompanying creep diffusion based matter transport is suggested to strongly support reorientation of ZnO particles towards densities beyond the theoretical limit for packing of ideal monosized spheres. Finally, the sintering trajectory reveals that grain growth is retarded compared to conventional processing up to 90% of theoretical density. Moreover, nearly no radial shrinkage was observed after sinter-forging for bodies performed with this advanced processing method. (paper)

  13. Characterization of a Viking Blade Fabricated by Traditional Forging Techniques

    Science.gov (United States)

    Vo, H.; Frazer, D.; Bailey, N.; Traylor, R.; Austin, J.; Pringle, J.; Bickel, J.; Connick, R.; Connick, W.; Hosemann, P.

    2016-12-01

    A team of students from the University of California, Berkeley, participated in a blade-smithing competition hosted by the Minerals, Metals, and Materials Society at the TMS 2015 144th annual meeting and exhibition. Motivated by ancient forging methods, the UC Berkeley team chose to fabricate our blade from historical smithing techniques utilizing naturally-occurring deposits of iron ore. This approach resulted in receiving the "Best Example of a Traditional Blade Process/Ore Smelting Technique" award for our blade named "Berkelium." First, iron-enriched sand was collected from local beaches. Magnetite (Fe3O4) was then extracted from the sand and smelted into individual high- and low-carbon steel ingots. Layers of high- and low-carbon steels were forge-welded together, predominantly by hand, to form a composite material. Optical microscopy, energy dispersive spectroscopy, and Vickers hardness mechanical testing were conducted at different stages throughout the blade-making process to evaluate the microstructure and hardness evolution during formation. It was found that the pre-heat-treated blade microstructure was composed of ferrite and pearlite, and contained many nonmetallic inclusions. A final heat treatment was performed, which caused the average hardness of the blade edge to increase by more than a factor of two, indicating a martensitic transformation.

  14. Fatigue and fracture behavior of low alloy ferritic forged steels

    International Nuclear Information System (INIS)

    Chaudhry, V.; Sharma, A.K.; Muktibodh, U.C.; Borwankar, Neeraj; Singh, D.K.; Srinivasan, K.N.; Kulkarni, R.G.

    2016-01-01

    Low alloy ferritic steels are widely used in nuclear industry for the construction of pressure vessels. Pressure vessel forged low alloy steels 20MnMoNi55 (modified) have been developed indigenously. Experiments have been carried out to study the Low Cycle Fatigue (LCF) and fracture behavior of these forged steels. Fully reversed strain controlled LCF testing at room temperature and at 350 °C has been carried out at a constant strain rate, and for different axial strain amplitude levels. LCF material behavior has been studied from cyclic stress-strain responses and the strain-life relationships. Fracture behavior of the steel has been studied based on tests carried out for crack growth rate and fracture toughness (J-R curve). Further, responses of fatigue crack growth rate tests have been compared with the rate evaluated from fatigue precracking carried out for fracture toughness (J-R) tests. Fractography of the samples have been carried out to reveal dominant damage mechanisms in crack propagation and fracture. The fatigue and fracture properties of indigenously developed low alloy steel 20MnMoNi55 (modified) steels are comparable with similar class of steels. (author)

  15. HYDROGEN-ASSISTED FRACTURE IN FORGED TYPE 304L AUSTENITIC STAINLESS STEEL

    Energy Technology Data Exchange (ETDEWEB)

    Switzner, Nathan; Neidt, Ted; Hollenbeck, John; Knutson, J.; Everhart, Wes; Hanlin, R. [University of Missouri-Kansas City; Bergen, R. [Precision Metal Products; Balch, D. K. [Sandia Natl Laboratory

    2012-09-06

    Austenitic stainless steels generally have good resistance to hydrogen-assisted fracture; however, structural designs for high-pressure gaseous hydrogen are constrained by the low strength of this class of material. Forging is used to increase the low strength of austenitic stainless steels, thus improving the efficiency of structural designs. Hydrogen-assisted racture, however, depends on microstructural details associated with manufacturing. In this study, hydrogen-assisted fracture of forged type 304L austenitic stainless steel is investigated. Microstructural variation in multi-step forged 304L was achieved by forging at different rates and temperatures, and by process annealing. High internal hydrogen content in forged type 304L austenitic stainless steel is achieved by thermal precharging in gaseous hydrogen and results in as much as 50% reduction of tensile ductility.

  16. Research on orbital cold forging for the edge cam of automobile fuel injection pump

    Science.gov (United States)

    Chi, Zhang; Bo, Xu

    2005-12-01

    The experimental investigation and theoretical analysis of an orbital cold forging of an edge cam was explored. The effects of blank shape and the process parameters on the edge cam forming are discussed. Photoplastic technology was successfully applied to the simulation of an orbital cold forging process applied to an edge cam. The China-made polycarbonate (PCBA) was used as a simulation material, and a 3-D strain distribution was obtained inside the model materials, which provided theoretical guidance for optimizing process parameters on the orbital cold forging of the edge cam. The factors that caused a crack were identified and the deformation laws in orbital cold forging of an edge cam were clarified. The metal flow line, hardness, microstructures and accuracy of the orbital cold forged edge cam were found to meet the required service properties of the product.

  17. U3O8 microspheres sintering kinetics

    International Nuclear Information System (INIS)

    Godoy, A.L.E.

    1986-01-01

    U 3 O 8 microspheres sintering kinetics was determined using a hot-stage optical microscopy apparatus, able to reach temperature up to 1350 0 C in controlled atmospheres. The sintered material had its microstructure analysed by optical and electron microscopy. The microspheres were characterized initialy utilizing X-ray diffractometry and thermogravimetry. The equation which describes the microspheres shrinkage in function of the time was obtained using finite difference analysis X-ray diffractometry indicated hexagonal structure for the microspheres main starting material, ammonium diuranate thermogravimetric analysis showed reduction of this material to U 3 O 8 at 600 0 C. Ceramography results showed 5 hours sintered microspheres grain sizes G vary with the temperature. Sintered U 3 O 8 micrographs compared with published results for UO 2 , indicate similar homogeneity microstructural characteristics and suggest the processed micorspheres to be potentially useful as nuclear fuels. (Author) [pt

  18. Thermal barrier coating resistant to sintering

    Science.gov (United States)

    Subramanian, Ramesh; Seth, Brij B.

    2004-06-29

    A device (10) is made, having a ceramic thermal barrier coating layer (16) characterized by a microstructure having gaps (18) with a sintering inhibiting material (22) disposed on the columns (20) within the gaps (18). The sintering resistant material (22) is stable over the range of operating temperatures of the device (10), is not soluble with the underlying ceramic layer (16) and is applied by a process that is not an electron beam physical vapor deposition process.

  19. Analysis of Laser Sintering Technology

    Directory of Open Access Journals (Sweden)

    Vladislav Markovič

    2014-02-01

    Full Text Available The new, high-tech development and customization is one ofthe most important factors in promoting the country‘s economicgrowth indicators. The economic downturn in the industryrequires technology and equipment using a minimumof raw materials and providing maximum performance. Thisstatement perfectly describes the innovative, forward-looking,cost-effective laser powder sintering (SLS technology. Here,thanks to the latest engineering achievements, product surfacesare modified and improved, they gain new characteristics. SLSis viable in automobile, engineering, construction, aerospace,aircraft, printing, medical and other areas.In order to create a product which meets the standards andtechnical documentation it is necessary to use and ensure highquality of raw materials, high-end equipment, qualified personnel,the working environment with proper climatic conditions, ergonomics,etc. But all of these, the quality of the product becomesthe decisive indicators meaningless if know how to properly selectthe laser processing operation. Scanning speed, beam power,pulse frequency, protective gases, powder layer thickness – allof them are the physical and mechanical characteristics of thechange in a small range changes the quality of the product of thefuture, the field of application and performance characteristics.

  20. Discrimination symbol applying method for sintered nuclear fuel product

    International Nuclear Information System (INIS)

    Ishizaki, Jin

    1998-01-01

    The present invention provides a symbol applying method for applying discrimination information such as an enrichment degree on the end face of a sintered nuclear product. Namely, discrimination symbols of information of powders are applied by a sintering aid to the end face of a molded member formed by molding nuclear fuel powders under pressure. Then, the molded product is sintered. The sintering aid comprises aluminum oxide, a mixture of aluminum oxide and silicon dioxide, aluminum hydride or aluminum stearate alone or in admixture. As an applying means of the sintering aid, discrimination symbols of information of powders are drawn by an isostearic acid on the end face of the molded product, and the sintering aid is sprayed thereto, or the sintering aid is applied directly, or the sintering aid is suspended in isostearic acid, and the suspension is applied with a brush. As a result, visible discrimination information can be applied to the sintered member easily. (N.H.)

  1. Solid-state sintering of tungsten heavy alloys

    International Nuclear Information System (INIS)

    Gurwell, W.E.

    1994-10-01

    Solid-state sintering is a technologically important step in the fabrication of tungsten heavy alloys. This work addresses practical variables affecting the sinterability: powder particle size, powder mixing, and sintering temperature and time. Compositions containing 1 to 10 micrometer (μM) tungsten (W) powders can be fully densified at temperatures near the matrix solidus. Blending with an intensifier bar provided good dispersion of elemental powders and good as-sintered mechanical properties under adequate sintering conditions. Additional ball milling increases powder bulk density which primarily benefits mold and die filling. Although fine, 1 μm W powder blends have high sinterability, higher as-sintered ductilities are reached in shorter sintering times with coarser, 5 μm W powder blends; 10μm W powder blends promise the highest as-sintered ductilities due to their coarse microstructural W

  2. Modelling of Damage During Hot Forging of Ingots

    DEFF Research Database (Denmark)

    Christiansen, Peter; Hattel, Jesper Henri; Bay, Niels

    2013-01-01

    Ductile damage modelling in the ingot forging process is discussed. Advantages and disadvantages of both coupled and uncoupled ductile damage models are presented. Some uncoupled damage models are examined in greater detail regarding their applicability to different processes, where hydrostatic...... compression as well as tension, combined with shear stresses, are present. It is shown that the numerical implementation can influence the results substantially and therefore lead to software user dependent conclusions. It may be advantageous for the user of commercial finite element programs to base...... the damage analysis on the Cockcroft & Latham criterion, since this with changing cut-off value does not inconsistently change the location of damage, in contradiction to the other investigated criteria, and since it is able to predict damage in processes, which are slightly compressive....

  3. Developments of New Lubricants for Cold Forging of Stainless Steel

    DEFF Research Database (Denmark)

    Steenberg, Thomas; Christensen, Erik; Olesen, P.

    1997-01-01

    Two new lubricant systems for cold forging of stainless steel have been developed. The main component of these systems are FeCl3 and ZnCa2(PO4)2, respectively. Both lubricant systems have been tested using a backward extrusion test. The results show excellent lubricating properties with respect...... to obtainable height of cup and friction. It is proposed that the formation of FeCl2 plays an important role in the lubrication mechanism of FeCl3. The ZnCa2(PO4)2 coating have been lubricated with sodium stearate and MoS2 and the best results were obtained with sodium stearate....

  4. Numerical optimization of die geometry in open die forging

    DEFF Research Database (Denmark)

    Christiansen, Peter; Hattel, Jesper Henri; Bay, Niels

    2013-01-01

    This paper deals with numerical optimization of open die forging of large metallic ingots made by casting implying risk of defects, e.g. central pores. Different material hardening properties and die geometries are combined in order to investigate, which geometry gives rise to maximum closure...... of a centreline hole in a single compression operation. Friction is also taken into account. The numerical analysis indicates that a lower die angle of approximately 140o results in the largest centreline hole closure for a wide range of material hardening. The value of optimum die angle is not influenced...... by friction, which was found only to change the degree of centreline porosity closure in case of small lower die angle....

  5. Experimentation and numerical modeling of forging induced bending (FIB) process

    Science.gov (United States)

    Naseem, S.; van den Boogaard, A. H.

    2016-10-01

    Accurate prediction of the final shape using numerical modeling has been a top priority in the field of sheet and bulk forming. Better shape prediction is the result of a better estimation of the physical stress and strain state. For experimental and numerical investigations of such estimations, simple benchmark processes are used. In this paper a benchmark process involving forging (flattening) of sheet metal between punch and die with negative clearance is proposed. The introduced material flow results in bending. Easy measurability of the angle of this bend makes this process suitable for validation purpose. Physical experiments are performed to characterize this bending angle due to flattening. Furthermore a numerical model is developed to capture this phenomenon. The main focus of this paper is the validation of the numerical model in terms of accurate prediction of the physical results.

  6. Effect of Cold Forging on Microstructure and MechanicalProperties of Al/SiC Composites

    Science.gov (United States)

    Hanamantraygouda, M. B.; Shivakumar, B. P., Dr; Siddappa, P. N.; Sampathkumar, L.; Prashanth, L.

    2018-02-01

    The objective of this work was to investigate the effect of cold forging on mechanical properties and microstructural study of Al MMCs, at different wt% of SiC and forging cycle. The Al-SiC composite material was fabricated by stir casting method at different weight percentage of SiC such as 2.5, 5, 7.5 and 10%. Further, the deformation characteristics during open-die forging of Al-SiC composite at cold conditions was investigated. Cast and forged composite material was subjected to hardness test, tensile test and impact test. The grain size, microstructure behaviour was investigated using optical microscope. The results show that hardness and strength of Al-SiC composite increases and ductility decreases as compared to Al alloy in both as-cast and forged conditions. Optical microscope images showed that the distribution of SiC in Al matrix was more homogeneous in a forged composite as compared to cast one and reduction of porosity was found. Further, it showed that due to forging cycle the grain size was reduced by 30% to 35% from initial size.

  7. Study on Manufacturing Process of Hollow Main Shaft by Open Die Forging

    International Nuclear Information System (INIS)

    Kwon, Yong Chul; Kang, Jong Hun; Kim, Sang Sik

    2016-01-01

    The main shaft is one of the key components connecting the rotor hub and gear box of a wind power generator. Typically, main shafts are manufactured by open die forging method. However, the main shaft for large MW class wind generators is designed to be hollow in order to reduce the weight. Additionally, the main shafts are manufactured by a casting process. This study aims to develop a manufacturing process for hollow main shafts by the open die forging method. The design of a forging process for a solid main shaft and hollow shaft was prepared by an open die forging process design scheme. Finite element analyses were performed to obtain the flow stress by a hot compression test at different temperature and strain rates. The control parameters of each forging process, such as temperature and effective strain, were obtained and compared to predict the suitability of the hollow main shaft forging process. Finally, high productivity reflecting material utilization ratio, internal quality, shape, and dimension was verified by the prototypes manufactured by the proposed forging process for hollow main shafts

  8. Hot Superplastic Powder Forging for Transparent nanocrystalline Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, W. Roger

    2006-05-22

    The program explored a completely new, economical method of manufacturing nanocrystalline ceramics, Hot Superplastic Powder Forging (HSPF). The goal of the work was the development of nanocrystalline/low porosity optically transparent zirconia/alumina. The high optical transparency should result from lack of grain boundary scattering since grains will be smaller than one tenth the wavelength of light and from elimination of porosity. An important technological potential for this process is manufacturing of envelopes for high-pressure sodium vapor lamps. The technique for fabricating monolithic nanocrystalline material does not begin with powder whose particle diameter is <100 nm as is commonly done. Instead it begins with powder whose particle diameter is on the order of 10-100 microns but contains nanocrystalline crystallites <<100 nm. Spherical particles are quenched from a melt and heat treated to achieve the desired microstructure. Under a moderate pressure within a die or a mold at temperatures of 1100C to 1300C densification is by plastic flow of superplastic particles. A nanocrystalline microstructure results, though some features are greater than 100nm. It was found, for instance, that in the fully dense Al2O3-ZrO2 eutectic specimens that a bicontinuous microstructure exists containing <100 nm ZrO2 particles in a matrix of Al2O3 grains extending over 1-2 microns. Crystallization, growth, phase development and creep during hot pressing and forging were studied for several compositions and so provided some details on development of polycrystalline microstructure from heating quenched ceramics.

  9. Follow-up of hearing thresholds among forge hammering workers

    Energy Technology Data Exchange (ETDEWEB)

    Kamal, A.A.; Mikael, R.A.; Faris, R. (Ain Shams Univ., Abbasia, Cairo (Egypt))

    1989-01-01

    Hearing threshold was reexamined in a group of forge hammering workers investigated 8 years ago with consideration of the age effect and of auditory symptoms. Workers were exposed to impact noise that ranged from 112 to 139 dB(A)--at an irregular rate of 20 to 50 drop/minute--and a continuous background noise that ranged from 90 to 94 dB(A). Similar to what was observed 8 years ago, the present permanent threshold shift (PTS) showed a maximum notch at the frequency of 6 kHz and considerable elevations at the frequencies of 0.25-1 kHz. The age-corrected PTS and the postexposure hearing threshold were significantly higher than the corresponding previous values at the frequencies 0.25, 0.5, 1, and 8 kHz only. The rise was more evident at the low than at the high frequencies. Temporary threshold shift (TTS) values were significantly less than those 8 years ago. Contrary to the previous TTS, the present TTS were higher at low than at high frequencies. Although progression of PTS at the frequencies 0.25 and 0.5 kHz was continuous throughout the observed durations of exposure, progression at higher frequencies occurred essentially in the first 10 to 15 years of exposure. Thereafter, it followed a much slower rate. Tinnitus was significantly associated with difficulty in hearing the human voice and with elevation of PTS at all the tested frequencies, while acoustic after-image was significantly associated with increment of PTS at the frequencies 0.25-2 kHz. No relation between PTS and smoking was found. PTS at low frequencies may provide an indication of progression of hearing damage when the sensitivity at 6 and 4 kHz diminishes after prolonged years of exposure. Tinnitus and acoustic after-image are related to the auditory effect of forge hammering noise.

  10. Preparation and characterization of a homemade Josephson junction prepared from a thin film sintered in a domestic microwave oven

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Gustavo Quereza; Moreto, Jeferson Aparecido [Instituto Federal de Educacao, Ciencia e Tecnologia Goiano (IFGO), Rio Verde, GO (Brazil); Zadorosny, Rafael; Silveira, Joao Borsil; Carvalho, Claudio Luiz [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Ilha Solteira, SP (Brazil); Cena, Cicero Rafael, E-mail: gustavoquereza@yahoo.com.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Sao Paulo (IFSP), Birigui, SP (Brazil)

    2016-03-15

    A homemade Josephson junction was successfully obtained using a superconductor thin film of the BSCCO system. The film was deposited on a lanthanum aluminate, produced from a commercial powder with a nominal composition Bi{sub 1.8}Pb{sub 0.4}Sr{sub 2}CaCu{sub 2}O{sub x}, was thermally treated by a domestic microwave oven. The XRD analysis of the film indicated the coexistence of Bi-2212 and Bi-2223 phases and SEM images revealed that a typical superconductor plate-like morphology was formed. From the electrical characterization, performed using DC four probes technique, it was observed an onset superconducting transition temperature measured around 81K. At the current-voltage characteristics curve, a step of electric current at zero-voltage could be observed, an indicative that the tunneling Josephson occurred. (author)

  11. Effect of Technical Quality of Thermomechanical Die Forging of AA2099 Alloy

    Directory of Open Access Journals (Sweden)

    Łukaszek-Sołek A.

    2014-10-01

    Full Text Available The paper presents the results of investigations of a multicomponent third-generation aluminium alloy, classified as AA2099. The actual forging conditions were determined basing on the assessment of the quality of side surface of specimens subjected to compression in Gleeble 3800 simulator and on flow curves of the alloy, as well as numerical modelling of forging process performed with application of QForm 3D v.7 software. Compression tests were realized at temperatures 400-500 °C, with a strain rate of 0.001-100 s-1, up to a specified constant true strain value of 0.9. Microstructure examination in as-delivered state was performed with application of Leica DM 4000M optical microscope. The obtained results of isothermal deformation of specimens were correlated with the analysis of a characteristic layered pancake-type microstructure. The simulation of die forging of a complex-shape forging (high-current contact tip used in power engineering at the temperature 500 °C, was performed. The shape of a forging makes it possible to fully analyse the influence of thermomechanical process conditions on technical quality of a product. The simulation of forging process showed full correctness of material flow, with no signs of instability. At the same time, the analysis of investigations allowed to prepare and realize the industrial forging trials for a forging of a very complex shape, in a single step, at the temperature 500 °C, with application of thermomechanical treatment. The forging attained high quality of shape and surface. Directional specimens were taken, in order to be subjected to microstructure examination and hardness testing. The data obtained from industrial tests, combined with the results of testing using Gleeble simulator as well as from numerical modelling, make up the guidelines for mechanical processing of AA2099 alloy at the temperatures 470-500 °C.

  12. Effects of sintering atmosphere and initial particle size on sintering of gadolinia-doped ceria

    International Nuclear Information System (INIS)

    Batista, Rafael Morgado

    2014-01-01

    The effects of the sintering atmosphere and initial particle size on the sintering of ceria containing 10 mol% gadolinia (GdO 1.5 ) were systematically investigated. The main physical parameter was the specific surface area of the initial powders. Nanometric powders with three different specific surface areas were utilized, 210 m 2 /g, 36,2 m 2 /g e 7,4 m 2 /g. The influence on the densification, and micro structural evolution were evaluated. The starting sintering temperature was verified to decrease with increasing on the specific surface area of raw powders. The densification was accelerated for the materials with smaller particle size. Sintering paths for crystallite growth were obtained. Master sintering curves for gadolinium-doped ceria were constructed for all initial powders. A computational program was developed for this purpose. The results for apparent activation energy showed noticeable dependence with specific surface area. In this work, the apparent activation energy for densification increased with the initial particle size of powders. The evolution of the particle size distributions on non isothermal sintering was investigated by WPPM method. It was verified that the grain growth controlling mechanism on gadolinia doped ceria is the pore drag for initial stage and beginning of intermediate stage. The effects of the sintering atmosphere on the stoichiometry deviation of ceria, densification, microstructure evolution, and electrical conductivity were analyzed. Inert, oxidizing, and reducing atmospheres were utilized on this work. Deviations on ceria stoichiometry were verified on the bulk materials. The deviation verified was dependent of the specific surface area and sintering atmosphere. Higher reduction potential atmospheres increase Ce 3+ bulk concentration after sintering. Accelerated grain growth and lower electrical conductivities were verified when reduction reactions are significantly present on sintering. (author)

  13. Qualitative Research of AZ31 Magnesium Alloy Aircraft Brackets Produced by a New Forging Method

    Directory of Open Access Journals (Sweden)

    Dziubińska A.

    2016-06-01

    Full Text Available The paper reports a selection of numerical and experimental results of a new closed-die forging method for producing AZ31 magnesium alloy aircraft brackets with one rib. The numerical modelling of the new forming process was performed by the finite element method.The distributions of stresses, strains, temperature and forces were examined. The numerical results confirmed that the forgings produced by the new forming method are correct. For this reason, the new forming process was verified experimentally. The experimental results showed good agreement with the numerical results. The produced forgings of AZ31 magnesium alloy aircraft brackets with one rib were then subjected to qualitative tests.

  14. Forge, Arquillian, Swarm and Spring Boot: All play and no effort makes Simon a productive boy

    CERN Document Server

    CERN. Geneva

    2017-01-01

    During this live coding session, Simon will shine some light on a range productivity tools that make software development a pleasure rather than a chore. Simon will live code 2 applications; a Java EE application, with JBoss Forge which uses JPA, Bean Validation, REST and Angular. We’ll test this application using Arquillian from within JBoss Forge. We’ll also show how a Java EE microservice can be developed in Forge and run using JBoss Swarm. The second application will be developed on Spring Boot and using JRebel we’ll rapidly develop and run a Spring application. Attendees will learn how to write code productively using tools designed for developers.

  15. Application of the CAB process for the manufacture of high-grade forgings

    International Nuclear Information System (INIS)

    Grimm, W.; Feller, J.; Plaul, H.U.

    1981-01-01

    The suitability of the ladle metallurgy CAB process (deoxidation and desulphurization with calcium and degassing with argon) is investigated for the manufacture of high-grade forgings for the construction of power-generating machines. The primary function of the CAB metallurgy, the improvement of the sulphide and oxide cleanness, was combined with established casting parameters so that the macrosegregates too in large forging ingots could be minimized. A comparison of various methods for the manufacture of large forging ingots revealed that the CAB metallurgy can meet demands, which so far could be satisfied by remelting technologies only. (orig.) [de

  16. Master sintering curve: A practical approach to its construction

    Directory of Open Access Journals (Sweden)

    Pouchly V.

    2010-01-01

    Full Text Available The concept of a Master Sintering Curve (MSC is a strong tool for optimizing the sintering process. However, constructing the MSC from sintering data involves complicated and time-consuming calculations. A practical method for the construction of a MSC is presented in the paper. With the help of a few dilatometric sintering experiments the newly developed software calculates the MSC and finds the optimal activation energy of a given material. The software, which also enables sintering prediction, was verified by sintering tetragonal and cubic zirconia, and alumina of two different particle sizes.

  17. Calcium Hex aluminate reaction sintering by Spark Plasma Sintering; Sinterizacion reactiva de Hexaluminato de Calcio mediante Spark Plasma Sintering

    Energy Technology Data Exchange (ETDEWEB)

    Iglesia, P. G. de la; Garcia-Moreno, O.; Torrecillas, R.; Menendez, J. L.

    2012-11-01

    Calcium hex aluminate (CaAl{sub 1}2O{sub 1}9) is the most alumina-rich intermediate compound of the CaO-Al{sub 2}O{sub 3} system. The formation of this aluminate is produced by the reaction between calcium oxide and alumina with the consequent formation of intermediates compounds with lower alumina content with increasing temperature (CaAl{sub 2}O{sub 4}, CaAl4O{sub 7}). In this study we studied the variation of sintering parameters for obtaining dense and pure calcium hex aluminate by reaction sintering by Spark Plasma Sintering (SPS). A mixing of Al{sub 2}O{sub 3} and CaCO{sub 3} were used as reactive. Final densities close to the theoretical and phase transformation over 93% were achieved by this method. (Author) 22 refs.

  18. Integrated analysis of oxide nuclear fuel sintering

    International Nuclear Information System (INIS)

    Baranov, V.; Kuzmin, R.; Tenishev, A.; Timoshin, I.; Khlunov, A.; Ivanov, A.; Petrov, I.

    2011-01-01

    Dilatometric and thermal-gravimetric investigations have been carried out for the sintering process of oxide nuclear fuel in gaseous Ar - 8% H 2 atmosphere at temperatures up to 1600 0 C. The pressed compacts were fabricated under real production conditions of the OAO MSZ with application of two different technologies, so called 'dry' and 'wet' technologies. Effects of the grain size growth after the heating to different temperatures were observed. In order to investigate the effects produced by rate of heating on properties of sintered fuel pellets, the heating rates were varied from 1 to 8 0 C per minute. Time of isothermal overexposure at maximal temperature (1600 0 C) was about 8 hours. Real production conditions were imitated. The results showed that the sintering process of the fuel pellets produced by two technologies differs. The samples sintered under different heating rates were studied with application of scanning electronic microscopy analysis for determination of mean grain size. A simulation of heating profile for industrial furnaces was performed to reduce the beam cycles and estimate the effects of variation of the isothermal overexposure temperatures. Based on this data, an optimization of the sintering conditions was performed in operations terms of OAO MSZ. (authors)

  19. New materials through a variety of sintering methods

    Science.gov (United States)

    Jaworska, L.; Cyboroń, J.; Cygan, S.; Laszkiewicz-Łukasik, J.; Podsiadło, M.; Novak, P.; Holovenko, Y.

    2018-03-01

    New sintering techniques make it possible to obtain materials with special properties that are impossible to obtain by conventional sintering techniques. This issue is especially important for ceramic materials for application under extreme conditions. Following the tendency to limit critical materials in manufacturing processes, the use of W, Si, B, Co, Cr should be limited, also. One of the cheapest and widely available materials is aluminum oxide, which shows differences in phase composition, grain size, hardness, strain and fracture toughness of the same type of powder, sintered via various methods. In this paper the alumina was sintered using the conventional free sintering process, microwave sintering, Spark Plasma Sintering (SPS), high pressure-high temperature method (HP-HT) and High Pressure Spark Plasma Sintering (HP SPS). Phase composition analysis, by X-ray diffraction of the alumina materials sintered using various methods, was carried out. For the conventional sintering method, compacts are composed of α-Al2O3 and θ-Al2O3. For compacts sintered using SPS, microwave and HP-HT methods, χ-Al2O3 and γ-Al2O3 phases were additionally present. Mechanical and physical properties of the obtained materials were compared between the methods of sintering. On the basis of images from scanning electron microscope quantitative analysis was performed to determine the degree of grain growth of alumina after sintering.

  20. High coercivity, anisotropic, heavy rare earth-free Nd-Fe-B by Flash Spark Plasma Sintering.

    Science.gov (United States)

    Castle, Elinor; Sheridan, Richard; Zhou, Wei; Grasso, Salvatore; Walton, Allan; Reece, Michael J

    2017-09-11

    In the drive to reduce the critical Heavy Rare Earth (HRE) content of magnets for green technologies, HRE-free Nd-Fe-B has become an attractive option. HRE is added to Nd-Fe-B to enhance the high temperature performance of the magnets. To produce similar high temperature properties without HRE, a crystallographically textured nanoscale grain structure is ideal; and this conventionally requires expensive "die upset" processing routes. Here, a Flash Spark Plasma Sintering (FSPS) process has been applied to a Dy-free Nd 30.0 Fe 61.8 Co 5.8 Ga 0.6 Al 0.1 B 0.9 melt spun powder (MQU-F, neo Magnequench). Rapid sinter-forging of a green compact to near theoretical density was achieved during the 10 s process, and therefore represents a quick and efficient means of producing die-upset Nd-Fe-B material. The microstructure of the FSPS samples was investigated by SEM and TEM imaging, and the observations were used to guide the optimisation of the process. The most optimal sample is compared directly to commercially die-upset forged (MQIII-F) material made from the same MQU-F powder. It is shown that the grain size of the FSPS material is halved in comparison to the MQIII-F material, leading to a 14% increase in coercivity (1438 kA m -1 ) and matched remanence (1.16 T) giving a BH max of 230 kJ m -3 .

  1. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.G.

    1975-01-01

    This patent describes a sintered product having substantially stable permanent magnet properties in air at room temperature. It comprises compacted particulate cobalt--rare earth alloy consisting essentially of a Co 5 R intermetallic phase and a CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase, where R is a rare earth metal. The Co 5 R intermetallic phase is present in an amount of at least 65 percent by weight of the sintered product and the CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase is present in a positive amount having a value ranging up to about 35 percent by weight of the product. The sintered product has a density of at least 87 percent and has pores which are substantially noninterconnecting and wherein the component grains have an average size less than 30 microns

  2. Method of manufacturing sintered nuclear fuel

    International Nuclear Information System (INIS)

    Watarumi, Kazutoshi.

    1984-01-01

    Purpose: To obtain composite pellets with an improved strength. Method: A core mainly composed of fuel materials is previously prepared, embedded into the central portion of a pellet, silted therearound with cladding material, and then pressmolded and sintered. For instance, a rugby-ball like core body with the maximum outer diameter of 6 mm and the height of 6 mm is made by compressive molding with uranium dioxide powder, then coating material comprising the same powder incorporated with 0.1 % by weight of SiC fibers is filled around the core body, which is molded into a composite pellet by means of pressing and then sintered at 1600 0 C, to obtain a sintered pellet of 93.5 % theoretical density. As the result of the compression test for the pellet, it showed a strength greater by 15 % than that of the similar mono-layer pellet. (Kamimura, M.)

  3. Sintering of nickel steam reforming catalysts

    DEFF Research Database (Denmark)

    Sehested, Jens; Larsen, Niels Wessel; Falsig, Hanne

    2014-01-01

    The lifetimes of heterogeneous catalysts in many widely used industrial processes are determined by the loss of active surface area. In this context, the underlying physical sintering mechanism and quantitative information about the rate of sintering at industrial conditions are relevant....... In this paper, particle migration and coalescence in nickel steam reforming catalysts is studied. Density functional theory calculations indicate that Ni-OH dominate nickel transport at nickel surfaces in the presence of steam and hydrogen as Ni-OH has the lowest combined energies of formation and diffusion...... compared to other potential nickel transport species. The relation between experimental catalyst sintering data and the effective mass diffusion constant for Ni-OH is established by numerical modelling of the particle migration and coalescence process. Using this relation, the effective mass diffusion...

  4. Design of sintering-stable heterogeneous catalysts

    DEFF Research Database (Denmark)

    Gallas-Hulin, Agata

    the crystalline framework of a zeolite creates a steric hindrance against agglomeration into larger clusters. In the present study, experimental protocols for encapsulation of metal nanoparticles inside zeolites were developed. Two different methodologies were proposed to encapsulate gold, palladium and platinum......One of the major issues in the use of metal nanoparticles in heterogeneous catalysis is sintering. Sintering occurs at elevated temperatures because of increased mobility of nanoparticles, leading to their agglomeration and, as a consequence, to the deactivation of the catalyst. It is an emerging...... problem especially for the noble metals-based catalysis. These metals being expensive and scarce, it is worth developing catalyst systems which preserve their activity over time. Encapsulation of nanoparticles inside zeolites is one of the ways to prevent sintering. Entrapment of nanoparticles inside...

  5. Fabrication of 200 mm Diameter Sintering Body of Skutterudite Thermoelectric Material by Spark Plasma Sintering

    Science.gov (United States)

    Tomida, T.; Sumiyoshi, A.; Nie, G.; Ochi, T.; Suzuki, S.; Kikuchi, M.; Mukaiyama, K.; Guo, J. Q.

    2017-05-01

    Filled skutterudite is a promising material for thermoelectric power generation because its ZT value is relatively high. However, mass production of high-performance thermoelectric materials remains a challenge. This study focused on the sintering process of thermoelectric materials. Large-diameter n-type (Yb or La, Ca, Al, Ga, In)0.8(Co, Fe)4Sb12 skutterudite sintering bodies with a small thickness were successfully produced by the spark plasma sintering (SPS) method. When direct current flows through the thermoelectric sintering body during the SPS pulse, the Peltier effect causes a temperature difference within the sintering body. To eliminate the Peltier effect, an electrical insulating material was inserted between the punch (electrode) and the sintering body. In this way, an n-type La-filled skutterudite sample with a diameter of 200 mm, thickness of 21 mm, and weight of 5 kg was successfully produced. The thermoelectric properties and microstructures of the sample were almost the same throughout the whole sintering body, and the dimensionless figure of merit reached 1.0 at 773 K.

  6. PRODUCTION OF WELDMENTS FROM SINTERED TITANIUM ALLOYS

    Directory of Open Access Journals (Sweden)

    A. YE. Kapustyan

    2014-04-01

    Full Text Available Purpose. Limited application of details from powder titanium alloys is connected with the difficulties in obtaining of long-length blanks, details of complex shape and large size. We can solve these problems by applying the welding production technology. For this it is necessary to conduct a research of the structure and mechanical properties of welded joints of sintered titanium alloys produced by flash welding. Methodology. Titanium industrial powders, type PT5-1 were used as original substance. Forming of blanks, whose chemical composition corresponded to BT1-0 alloy, was carried out using the powder metallurgy method. Compounds were obtained by flash welding without preheating. Microstructural investigations and mechanical tests were carried out. To compare the results investigations of BT1-0 cast alloy were conducted. Findings. Samples of welded joints of sintered titanium blanks from VT1-0 alloy using the flash butt welding method were obtained. During welding the microstructure of basic metal consisting of grains of an a-phase, with sizes 40...70 mkm, is transformed for the seam weld and HAZ into the lamellar structure of an a-phase. The remaining pores in seam weld were practically absent; in the HAZ their size was up to 2 mkm, with 30 mkm in the basic metal. Attainable level of mechanical properties of the welded joint in sintered titanium alloys is comparable to the basic metal. Originality. Structure qualitative changes and attainable property complex of compounds of sintered titanium alloys, formed as a result of flash butt welding were found out. Practical value. The principal possibility of high-quality compounds obtaining of sintered titanium alloys by flash welding is shown. This gives a basis for wider application of sintered titanium alloys due to long-length blanks production that are correspond to deformable strand semi finished product.

  7. Application of CAD/CAE/CAM in forging process: a review

    International Nuclear Information System (INIS)

    Ahmad Baharuddin Abdullah; Hamouda, A.M.S.

    2005-01-01

    Forging can be described as the process in which metal is plastically deformed with application of huge pressure. The process not only changes the shape but also improves the properties of the forged parts due to grain size refinement. Conventionally, the empirical trial and error method has been applied, but recently there are various tools are employed to improved product quality and economic of the process. For example, Computer Aided Design (CAD) is widely used in modeling of the process, while Computer Aided Engineering (CAE) tools have been utilized in analyzing the process. To physically demonstrate the process, Computer Aided Manufacturing (CAM) such as CNC machine has been exploited. In order to improve forging process efficiency, an integrated system that combines all advantages of CAD, CAM and CAE need to be developed. This paper presents an overview of computer aided simulation such as CAD, CAE and CAM application in forging process. (Author)

  8. Numerical die life estimation of a crack susceptible industrial hot forging process

    Science.gov (United States)

    Bouguecha, A.; Behrens, B.-A.; Bonk, C.; Rosenbusch, D.; Kazhai, M.

    2017-10-01

    In industrial hot forging processes, the forging dies underlie cyclic thermo-mechanical loads, which can lead to failure of the tools. Besides die wear (abrasive and adhesive) on the surface, fatigue crack initiation with a following fracture of the tool is one of the most frequent failures occurring in hot forging processes. In this study an industrial hot forging process is considered for fatigue analysis. Tool geometry is designed for a defined life time until crack initiated failure of the tool. Material characterization tests in form of tensile tests as well as cylindrical compression tests and low cycle fatigue tests were carried out. The data will be implemented in a commercial software-system to realize a qualitative good prediction of die life regarding crack wiation.

  9. Phase characterisation in spark plasma sintered TiPt alloy

    CSIR Research Space (South Africa)

    Chikosha, S

    2011-12-01

    Full Text Available The conclusions drawn from this presentation are that Spark Plasma Sintering (SPS) of equiatomic BE TiPt powder produces fully sintered specimens, with incomplete homogenisation. There is a need for improved furnace atmosphere control so...

  10. Process for microwave sintering boron carbide

    Science.gov (United States)

    Holcombe, C.E.; Morrow, M.S.

    1993-10-12

    A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

  11. Fusibility and sintering characteristics of ash

    International Nuclear Information System (INIS)

    Ots, A. A.

    2012-01-01

    The temperature characteristics of ash fusibility are studied for a wide range of bituminous and brown coals, lignites, and shales with ratios R B/A of their alkaline and acid components between 0.03 and 4. Acritical value of R B/A is found at which the fusion temperatures are minimal. The sintering properties of the ashes are determined by measuring the force required to fracture a cylindrical sample. It is found that the strength of the samples increases sharply at certain temperatures. The alkali metal content of the ashes has a strong effect on their sintering characteristics.

  12. Manufacturing technology of large integrated forgings supporting to global Nuclear Renaissance

    International Nuclear Information System (INIS)

    Sato, Ikuo; Iwamoto, Takashi

    2009-01-01

    Currently, nuclear power is reevaluated as clean energy to reduce greenhouse gas emission in worldwide and so called Nuclear Renaissance. At the start or under planning of construction of new nuclear power plants, it is important to turn round the development and manufacturing of large integrated forgings to improve the safety and reliability of components. In order to support the Nuclear Renaissance, it is necessary to increase the manufacturing capability for forgings. (author)

  13. Development of strategies for saving energy by temperature reduction in warm forging processes

    Science.gov (United States)

    Varela, Sonia; Santos, Maite; Vadillo, Leire; Idoyaga, Zuriñe; Valbuena, Óscar

    2016-10-01

    This paper is associated to the European policy of increasing efficiency in raw material and energy usage. This policy becomes even more important in sectors consuming high amount of resources, like hot forging industry, where material costs sums up to 50% of component price and energy ones are continuously raising. The warm forging shows a clear potential of raw material reduction (near-net-shape components) and also of energy saving (forging temperature under 1000°C). However and due to the increment of the energy costs, new solutions are required by the forging sector in order to reduce the temperature below 900°C. The reported research is based on several approaches to reduce the forging temperature applied to a flanged shaft of the automotive sector as demonstration case. The developed investigations have included several aspects: raw material, process parameters, tools and dies behavior during forging process and also metallographic evaluation of the forged parts. This paper summarizes analysis of the ductility and the admissible forces of the flanged shaft material Ck45 in as-supplied state (as-rolled) and also in two additional heat treated states. Hot compression and tensile tests using a GLEEBLE 3800C Thermo mechanical simulator have been performed pursuing this target. In the same way, a coupled numerical model based on Finite Element Method (FEM) has been developed to predict the material flow, the forging loads and the stresses on the tools at lower temperature with the new heat treatments of the raw material. In order to validate the previous development, experimental trials at 850 °C and 750 °C were carried out in a mechanical press and the results were very promising.

  14. Deformation, recrystallization, strength, and fracture of press-forged ceramic crystals.

    Science.gov (United States)

    Rice, R. W.

    1972-01-01

    Sapphire and ruby were very difficult to press-forge because they deformed without cracking only in a limited temperature range before they melted. Spinel crystals were somewhat easier and MgO, CaO, and TiC crystals much easier to forge. The degree of recrystallization that occurred during forging (which was related to the ease and type of slip intersections) varied from essentially zero in Al2O3 to complete (i.e., random polycrystalline bodies were produced) in CaO. Forging of bi- and polycrystalline bodies produced incoherent bodies as a result of grain-boundary sliding. Strengths of the forged crystals were comparable to those of dense polycrystalline bodies of similar grain size. However, forged and recrystallized CaO crystals were ductile at lower temperatures than dense hot-pressed CaO. This behavior is attributed to reduced grain-boundary impurities and porosity. Fracture origins could be located, indicating that fracture in the CaO occurs internally as a result of surface work hardening caused by machining.-

  15. Sintering of dioxide pellets in an oxidizing atmosphere (CO2)

    International Nuclear Information System (INIS)

    Santos, G.R.T.

    1992-01-01

    This work consists in the study of the sintering process of U O 2 pellets in an oxidizing atmosphere. Sintering tests were performed in an CO 2 atmosphere and the influence of temperature and time on the pellets density and microstructure were verified. The results obtained were compared to those from the conventional sintering process and its efficiency was confirmed. (author)

  16. Effect of increasing lanthanum substitution and the sintering ...

    Indian Academy of Sciences (India)

    Administrator

    Young's modulus of the microwave sintered samples (8.8–12.5 and 160–180 GPa) are higher than that for conventional sintered (8–10 and 135–155 GPa) samples. Keywords. Microwave sintering; La-substituted SBTi ceramics; mechanical properties. 1. Introduction. In recent years, bismuth layer-structured ferroelectrics.

  17. Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

    International Nuclear Information System (INIS)

    Wang, G.P.; Liu, W.Q.; Huang, Y.L.; Ma, S.C.; Zhong, Z.C.

    2014-01-01

    Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively

  18. Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G.P., E-mail: wgp@jxnu.edu.cn [College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022 (China); Liu, W.Q. [Key Laboratory of Advanced Functional Materials Science and Engineering, Ministry of Education, Beijing University of Technology, Beijing 100022 (China); Huang, Y.L.; Ma, S.C.; Zhong, Z.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2014-01-15

    Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively.

  19. Movement Synchrony Forges Social Bonds Across Group Divides

    Directory of Open Access Journals (Sweden)

    Bahar eTuncgenc

    2016-05-01

    Full Text Available Group dynamics play an important role in the social interactions of both children and adults. A large amount of research has shown that merely being allocated to arbitrarily defined groups can evoke disproportionately positive attitudes toward one’s in-group and negative attitudes toward out-groups, and that these biases emerge in early childhood. This prompts important empirical questions with far-reaching theoretical and applied significance. How robust are these inter-group biases? Can biases be mitigated by behaviors known to bond individuals and groups together? How can bonds be forged across existing group divides? To explore these questions, we examined the bonding effects of interpersonal synchrony on minimally constructed groups in a controlled experiment. In-group and out-group bonding were assessed using questionnaires administered before and after a task in which groups performed movements either synchronously or non-synchronously in a between-participants design. We also developed an implicit behavioral measure, the Island Game, in which physical proximity was used as an indirect measure of interpersonal closeness. Self-report and behavioral measures showed increased bonding between groups after synchronous movement. Bonding with the out-group was significantly higher in the condition in which movements were performed synchronously than when movements were performed non-synchronously between groups. The findings are discussed in terms of their importance for the developmental social psychology of group dynamics as well as their implications for applied intervention programs.

  20. Forged seal detection based on the seal overlay metric.

    Science.gov (United States)

    Lee, Joong; Kong, Seong G; Lee, Young-Soo; Moon, Ki-Woong; Jeon, Oc-Yeub; Han, Jong Hyun; Lee, Bong-Woo; Seo, Joong-Suk

    2012-01-10

    This paper describes a method for verifying the authenticity of a seal impression imprinted on a document based on the seal overlay metric, which refers to the ratio of an effective seal impression pattern and the noise in the neighborhood of the reference impression region. A reference seal pattern is obtained by taking the average of a number of high-quality impressions of a genuine seal. A target seal impression to be examined, often on paper with some background texts and lines, is segmented out from the background by an adaptive threshold applied to the histogram of color components. The segmented target seal impression is then spatially aligned with the reference by maximizing the count of matching pixels. Then the seal overlay metric is computed for the reference and the target. If the overlay metric of a target seal is below a predetermined limit for the similarity to the genuine, then the target is classified as a forged seal. To further reduce the misclassification rate, the seal overlay metric is adjusted by the filling rate, which reflects the quality of inked pattern of the target seal. Experiment results demonstrate that the proposed method can detect elaborate seal impressions created by advanced forgery techniques such as lithography and computer-aided manufacturing. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  1. Mechanical characteristics of microwave sintered silicon carbide

    Indian Academy of Sciences (India)

    Unknown

    tions ranging from kiln furniture to membrane material. Keywords. Microwave sintering; biaxial flexure; silicon carbide. 1. Introduction. Silicon carbide (SiC) ceramics is a very well known candidate material for a structural application. However, due to (i) poor densification due to highly directional bonding, (ii) susceptibility of ...

  2. Sintering behavior of LZSA glass-ceramics

    Directory of Open Access Journals (Sweden)

    Oscar Rubem Klegues Montedo

    2009-06-01

    Full Text Available The LZSA glass-ceramic system (Li2O-ZrO2-SiO2-Al2O 3 shows interesting properties, such as good chemical resistance, low thermal expansion, high abrasion resistance, and a low dielectric constant. However, in order to obtain a high performance material for specific applications, the sintering behavior must be better understood so that the porosity may be reduced and other properties improved. In this context, a sintering investigation for a specific LZSA glass-ceramic system composition was carried out. A 18.8Li2O-8.3ZrO2-64.2SiO2-8.7Al 2O3 glass was prepared by melting the solids, quenching the melt in water, and grinding the resulting solid in order to obtain a powder (3.68 μm average particle diameter. Subsequently, the glass powder was characterized (chemical analysis and determination of thermal properties and the sintering behavior was investigated using optical non-contact dilatometry measurements. The results showed that the crystallization process strongly reduced the sintering in the temperature interval from 785 to 940 °C, and a maximum thermal shrinkage of 15.4% was obtained with operating conditions of 1020 °C and 180 minutes.

  3. Low temperature sintering of hyperstoichiometric uranium dioxide

    International Nuclear Information System (INIS)

    Chevrel, H.

    1991-12-01

    In the lattice of uranium dioxide with hyperstoichiometric oxygen content (UO 2+x ), each additional oxygen atoms is introduced by shifting two anions from normal sites to interstitial ones, thereby creating two oxygen vacancies. The point defects then combine to form complex defects comprising several interstitials and vacancies. The group of anions (3x) in the interstitial position participate in equilibria promoting the creation of uranium vacancies thereby considerably increasing uranium self-diffusion. However, uranium grain boundaries diffusion governs densification during the first two stages of sintering of uranium dioxide with hyperstoichiometric oxygen content, i.e., up to 93% of the theoretical density. Surface diffusion and evaporation-condensation, which are considerably accentuated by the hyperstoichiometric deviation, play an active role during sintering by promoting crystalline growth during the second and third stages of sintering. U 8 O 8 can be added to adjust the stoichiometry and to form a finely porous structure and thus increase the pore area subjected to surface phenomena. The composition with an O/U ratio equal to 2.25 is found to densify the best, despite a linear growth in sintering activation energy with hyperstoichiometric oxygen content, increasing from 300 kj.mol -1 for UO 2.10 to 440 kJ.mol -1 for UO 2.25 . Seeds can be introduced to obtain original microstructures, for example the presence of large grains in small-grain matrix

  4. Study of ceramics sintering under high pressures

    International Nuclear Information System (INIS)

    Kunrath Neto, A.O.

    1990-01-01

    A systematic study was made on high pressure sintering of ceramics in order to obtain materials with controlled microstructure, which are not accessible by conventional methods. Some aspects with particular interest were: to achieve very low porosity, with fine grains; to produce dispersed metastable and denser phases which can act as toughening agents; the study of new possibilities for toughening enhancement. (author)

  5. Deformation behavior of sintered nanocrystalline silver layers

    International Nuclear Information System (INIS)

    Zabihzadeh, S.; Van Petegem, S.; Duarte, L.I.; Mokso, R.; Cervellino, A.; Van Swygenhoven, H.

    2015-01-01

    The microstructure of porous silver layers produced under different low temperature pressure-assisted sintering conditions is characterized and linked with the mechanical behavior studied in situ during X-ray diffraction. Peak profile analysis reveals important strain recovery and hardening mechanism during cyclic deformation. The competition between both mechanisms is discussed in terms of porosity and grain size

  6. Air-sintering mechanisms of chromites

    Energy Technology Data Exchange (ETDEWEB)

    Chick, L.A.; Bates, J.L.; Maupin, G.D.

    1991-07-01

    The sintering behaviors of La{sub 1-x}Sr{sub x}CrO{sub 3} and Y{sub 1-x}Ca{sub x}CrO{sub 3} in air at 1550{degrees}C are described as functions of alkaline earth concentration and chromium enrichment or depletion. Vapor-, liquid-, and solid-phase mass transport mechanisms appear to be operative in both systems. Liquid-phase sintering appears dominant an Y{sub 1-x}Ca{sub x}CrO{sub 3} with x = 0.15 to 0.40, especially with Cr enrichment. Either vapor- or solid-phase transport may dominate in the La{sub 1-x}Sr{sub x}CrO{sub 3} system. Slight depletion or enrichment of Cr in both systems has dramatic effects on air-sintered density and microstructure, probably due to modulation of vapor-phase transport and liquid-phase formation. Substantial Cr depletion enhances sintering. 10 refs., 9 figs.

  7. Mechanical characterization of microwave sintered zinc oxide

    Indian Academy of Sciences (India)

    Unknown

    Keywords. Zinc oxide; microwave sintering; microhardness. 1. Introduction. The application of microwave energy for the processing of ceramics has become an attractive area of research and innovation recently. The major advantages of the micro- wave processing of ceramic materials are accelerated densification rate as a ...

  8. Laser Sintering Technology and Balling Phenomenon.

    Science.gov (United States)

    Oyar, Perihan

    2018-02-01

    The aim of this review was to evaluate the balling phenomenon which occurs typically in Selective Laser Sintering (SLS). The balling phenomenon is a typical SLS defect, and observed in laser sintered powder, significantly reduces the quality of SLS, and hinders the further development of SLS Technology. Electronic database searches were performed using Google Scholar. The keywords "laser sintering, selective laser sintering, direct metal laser melting, and balling phenomenon" were searched in title/abstract of publications, limited to December 31, 2016. The inclusion criteria were SLS, balling phenomenon, some alloys (such as Cr-Co, iron, stainless steel, and Cu-based alloys) mechanical properties, microstructure and bond strength between metal-ceramic crown, laboratory studies, full text, and in English language. A total of 100 articles were found the initial search and yielded a total of 50 studies, 30 of which did not fulfill the inclusion criteria and were therefore excluded. In addition, 20 studies were found by screening the reference list of all included publications. Finally, 40 studies were selected for this review. The method in question is regulated by powder material characteristics and the conditions of laser processing. The procedure of formation, affecting factors, and the mechanism of the balling effect are very complex.

  9. Sintering of silicon nitride ceramics with magnesium silicon nitride and yttrium oxide as sintering aids

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, J; Xu, J Y [Shanghai Institute of Technology, Shanghai 200235 (China); Peng, G H [Guangxi Normal University, Guilin 541004, Guangxi (China); Zhuang, H R; Li, W L; Xu, S Y [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Mao, Y J, E-mail: guojianjiang@sit.edu.cn [Shanghai University, Shanghai 200444 (China)

    2011-10-29

    Silicon nitride (Si{sub 3}N{sub 4}) ceramics had been produced through pressureless sintering and hot-pressing sintering with MgSiN{sub 2}-Y{sub 2}O{sub 3} or only MgSiN{sub 2} as sintering aids. The influences of the amount of MgSiN{sub 2} and Y{sub 2}O{sub 3} and sintering methods on the properties of Si{sub 3}N{sub 4} ceramics were investigated. The results show that the bend strength of Si{sub 3}N{sub 4} ceramic fabricated through pressureless sintering at 1820 deg. C for 4 h with 5.6 wt.% MgSiN{sub 2}-15.8 wt.% Y{sub 2}O{sub 3} as sintering additive could achieve 839 MPa. However, the bend strength of Si{sub 3}N{sub 4} ceramic produced by hot-pressing sintering at 1750 deg. C for 1 h under uniaxial pressure of 20 MPa with 4.76 wt.% MgSiN{sub 2} was 1149 MPa. The thermal conductivity of the Si{sub 3}N{sub 4} ceramic 2 3 4 could reach to 129 W{center_dot}m{sup -1{center_dot}}K{sup 1}. The present work demonstrated that MgSiN{sub 2} aids and hot-pressing sintering were effective to improve the thermal conductivity of Si{sub 3}N{sub 4} ceramic.

  10. Yttrium oxide transparent ceramics by low-temperature microwave sintering

    International Nuclear Information System (INIS)

    Luo, Junming; Zhong, Zhenchen; Xu, Jilin

    2012-01-01

    Graphical abstract: The figure shows the SEM photos of the surfaces of the Y 2 O 3 transparent ceramic samples obtained by microwave sintering and vacuum sintering. It is clearly demonstrated that the grain distribution of the vacuum sintering sample is not uniform with the smallest and the largest particle size at about 2 μm and 15 μm respectively, while the grain distribution of microwave sintering sample is uniform with the average diameter at about 2–4 μm (the smallest reported so far) and with no abnormal growth-up or coarsening phenomenon. We have further found out that the smaller the grain size, the higher the mechanical and optical properties. Display Omitted Highlights: ► The microwave sintering temperature of the sample is lower compared with vacuum. ► The microwave sintering time of the sample is shorter compared with vacuum. ► The mechanical properties of the microwave sintering sample is improved greatly. ► The Y 2 O 3 grain of microwave sintering sample is the smallest reported so far. -- Abstract: Yttrium oxide (Y 2 O 3 ) transparent ceramics samples have been successfully fabricated by microwave sintering processing at relatively low temperatures. In comparison with the vacuum sintering processing, Y 2 O 3 transparent ceramics can be obtained by microwave sintering at lower sintering temperature and shorter sintering time, and they possess higher transmittances and mechanical properties. The technologies of low-temperature microwave sintering and the relationships of the microstructures and properties of the specified samples have been investigated in detail. We have found out that the low-temperature microwave sintering technique has its obvious advantages over the conventional methods in manufacturing yttrium oxide transparent ceramics.

  11. TiO2 doped UO2 fuels sintered by spark plasma sintering

    Science.gov (United States)

    Yao, Tiankai; Scott, Spencer M.; Xin, Guoqing; Lian, Jie

    2016-02-01

    UO2 fuels doped with oxide additives Cr2O3 and TiO2 display larger grain size, improving fission product retention capability and thus accident tolerance. Spark plasma sintering (SPS) was applied to consolidate TiO2-doped UO2 fuel pellets with 0.5 wt % dopant concentration, above its solubility, in order to induce eutectic phase formation and promote sintering kinetics. The grain size can reach 80 μm by sintering at 1700 °C for 20 min, and liquid U-Ti-O eutectic phase occurs at the triple junction of grain boundaries and significantly improves grain growth during sintering. The oxide additive also impedes the reduction of the initial hyperstoichiometric fuel powders to more stoichiometric fuel pellets upon SPS process. Thermal-mechanical properties of the sintered doped fuel pellets including thermal conductivity and hardness are measured and compared with undoped fuel pellets. The enlarged grain size (80 μm) and densification within short sintering duration highlight the immense possibility of SPS in fabricating large grained UO2 fuel pellets to improve fuel performance.

  12. Comparison of pitting fatigue life of ausforged and standard forged AISI M-50 and AISI 9310 spur gears

    Science.gov (United States)

    Townsend, D. P.; Bamberger, E. N.; Zaretsky, E. V.

    1975-01-01

    Standard forged and ausforged spur gears made of vacuum-induction-melted, consumable-electrode, vacuum-arc-remelted AISI M-50 steel were tested under conditions that produced fatigue pitting. The gears were 8.89 cm (3.5 in.) in pitch diameter and had tip relief. The M-50 standard forged and ausforged test results were compared with each other. They were then compared with results for machined vacuum-arc-remelted AISI 9310 gears tested under identical conditions. Both types of M-50 gears had lives approximately five times that of the 9310 gears. The life at which 10 percent of the M-50 ausforged gears failed was slightly less than that at which the M-50 standard forged gears failed. The ausforged gears had a slightly greater tendency to fail by tooth fracture than did the standard forged gears, most likely because of the better forging and grain flow pattern of standard forged gears.

  13. Sintering uranium oxide using a preheating step

    International Nuclear Information System (INIS)

    Jensen, N.J.; Nivas, Y.; Packard, D.R.

    1977-01-01

    Compacted pellets of uranium oxide or uranium oxide with one or more additives are heated in a kiln in a process having a preheating step, a sintering step, a reduction step, and a cooling step in a controlled atmosphere. The process is practiced to give a range of temperature and atmosphere conditions for obtaining optimum fluoride removal from the compacted pellets along with optimum sintering in a single process. The preheating step of this process is conducted in a temperature range of about 600 0 to about 900 0 C and the pellets are held for at least twenty min, and preferably about 60 min, in an atmosphere having a composition in the range of about 10 to about 75 vol % hydrogen with the balance being carbon dioxide. The sintering step is conducted at a temperature in the range of about 900 0 C to 1500 0 C in the presence of an atmosphere having a composition in the range of about 0.5 to about 90 vol % hydrogen with the balance being carbon dioxide. The reduction step reduces the oxygen to metal ratio of the pellets to a range of about 1.98 to 2.10:1 and this is accomplished by gradually cooling the pellets for about 30 to about 120 min from the temperature of the sintering step to about 1100 0 C in an atmosphere of about 10 to 90 vol % hydrogen with the balance being carbon dioxide. Thereafter the pellets are cooled to about 100 0 C under a protective atmosphere, and in one preferred practice the same atmosphere used in the reduction step is used in the cooling step. The preheating, sintering and reduction steps may also be conducted with their respective atmospheres having an initial additional component of water vapor and the water vapor can comprise up to about 20 vol %

  14. Comparative sinterability of combustion synthesized and commercial titanium carbides

    International Nuclear Information System (INIS)

    Manley, B.W.

    1984-11-01

    The influence of various parameters on the sinterability of combustion synthesized titanium carbide was investigaged. Titanium carbide powders, prepared by the combustion synthesis process, were sintered in the temperature range 1150 to 1600 0 C. Incomplete combustion and high oxygen contents were found to be the cause of reduced shrinkage during sintering of the combustion syntheized powders when compared to the shrinkage of commercial TiC. Free carbon was shown to inhibit shrinkage. The activation energy for sintering was found to depend on stoichiometry (C/Ti). With decreasing C/Ti, the rate of sintering increased. 29 references, 16 figures, 13 tables

  15. Phase transformation of NiTi alloys during vacuum sintering

    Science.gov (United States)

    Wang, Jun; Hu, Kuang

    2017-05-01

    The aim of this study is to ascertain the Phase transformation of NiTi alloys during vacuum sintering. NiTi shape memory alloys (SMA) of atomic ratio 1:1 were prepared through press forming and vacuum sintering with the mixture of Ni and Ti powders. Different samples were prepared by changing the sintering time and the sintering temperature. Phase and porosity of the samples were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that in the process of sintering NiTi2 and Ni3Ti phases are formed firstly and then transform into NiTi phase. The quantity of NiTi2 and Ni3Ti phases gradually decreased but not eliminate completely with increase of sintering time. The porosity of specimen sintering at 900°C decreases slightly with increase of sintering time. With increase of sintering time the porosity of specimen sintering at 1050°C decreased firstly and then increased because of generation rich titanium liquid in the process of sintering.

  16. Spark plasma sintering of hydrothermally synthesized bismuth ferrite

    Directory of Open Access Journals (Sweden)

    Zorica Branković

    2016-12-01

    Full Text Available Bismuth ferrite, BiFeO3 (BFO, powder was synthesized by hydrothermal method from Bi(NO33·5 H2O and Fe(NO33·9 H2O as precursors. The synthesized powder was further sintered using spark plasma sintering (SPS. The sintering conditions were optimized in order to achieve high density, minimal amount of secondary phases and improved ferroelectric and magnetic properties. The optimal structure and properties were achieved after spark plasma sintering at 630 °C for 20 min, under uniaxial pressure of 90 MPa. The composition, microstructure, ferroelectric and magnetic properties of the SPS samples were characterized and compared to those of conventionally sintered ceramics obtained from the same powder. Although the samples sintered using conventional method showed slightly lower amount of secondary phases, the spark plasma sintered samples exhibited favourable microstructure and better ferroelectric properties.

  17. Making randomised trials more efficient: report of the first meeting to discuss the Trial Forge platform.

    Science.gov (United States)

    Treweek, Shaun; Altman, Doug G; Bower, Peter; Campbell, Marion; Chalmers, Iain; Cotton, Seonaidh; Craig, Peter; Crosby, David; Davidson, Peter; Devane, Declan; Duley, Lelia; Dunn, Janet; Elbourne, Diana; Farrell, Barbara; Gamble, Carrol; Gillies, Katie; Hood, Kerry; Lang, Trudie; Littleford, Roberta; Loudon, Kirsty; McDonald, Alison; McPherson, Gladys; Nelson, Annmarie; Norrie, John; Ramsay, Craig; Sandercock, Peter; Shanahan, Daniel R; Summerskill, William; Sydes, Matt; Williamson, Paula; Clarke, Mike

    2015-06-05

    Randomised trials are at the heart of evidence-based healthcare, but the methods and infrastructure for conducting these sometimes complex studies are largely evidence free. Trial Forge ( www.trialforge.org ) is an initiative that aims to increase the evidence base for trial decision making and, in doing so, to improve trial efficiency.This paper summarises a one-day workshop held in Edinburgh on 10 July 2014 to discuss Trial Forge and how to advance this initiative. We first outline the problem of inefficiency in randomised trials and go on to describe Trial Forge. We present participants' views on the processes in the life of a randomised trial that should be covered by Trial Forge.General support existed at the workshop for the Trial Forge approach to increase the evidence base for making randomised trial decisions and for improving trial efficiency. Agreed upon key processes included choosing the right research question; logistical planning for delivery, training of staff, recruitment, and retention; data management and dissemination; and close down. The process of linking to existing initiatives where possible was considered crucial. Trial Forge will not be a guideline or a checklist but a 'go to' website for research on randomised trials methods, with a linked programme of applied methodology research, coupled to an effective evidence-dissemination process. Moreover, it will support an informal network of interested trialists who meet virtually (online) and occasionally in person to build capacity and knowledge in the design and conduct of efficient randomised trials.Some of the resources invested in randomised trials are wasted because of limited evidence upon which to base many aspects of design, conduct, analysis, and reporting of clinical trials. Trial Forge will help to address this lack of evidence.

  18. Optimization and mechanical accuracy reliability of a new type of forging manipulator

    Science.gov (United States)

    Chen, Kang; Ma, Chunxiang; Zheng, Maoqi; Gao, Feng

    2015-03-01

    Researches on forging manipulator have enormous influence on the development of the forging industry and national economy. Clamp device and lifting mechanism are the core parts of forging manipulator, and have been studied for longer time. However, the optimization and mechanical accuracy reliability of them are less analyzed. Based on General Function( G F) set and parallel mechanism theory, proper configuration of 10t forging manipulator is selected firstly. A new type of forging manipulator driven by cylinders is proposed. After solved mechanical analysis of manipulator's core mechanisms, expressions of force of cylinders are carried out. In order to achieve smaller force afforded by cylinders and better mechanical characteristics, some particular sizes of core mechanisms are optimized intuitively through the combined use of the genetic algorithms(GA) and GUI interface in MATLAB. Comparing with the original mechanisms, optimized clamp saves at least 8 percent efforts and optimized lifting mechanism 20 percent under maximum working condition. Finally, considering the existed manufacture error of components, mechanical accuracy reliability of optimized clamp, lifting mechanism and whole manipulator are demonstrated respectively based on fuzzy reliability theory. Obtained results show that the accuracy reliability of optimized clamp is bigger than 0.991 and that of optimized lifting mechanism is 0.995. To the whole manipulator under maximum working condition, that value exceeds 0.986 4, which means that optimized manipulator has high motion accuracy and is reliable. A new intuitive method is created to optimize forging manipulator sizes efficiently and more practical theory is utilized to analyze mechanical accuracy reliability of forging manipulator precisely.

  19. Effects of LaB{sub 6} additions on the microstructure and mechanical properties of a sintered and hot worked P/M Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Jia; Gabbitas, Brian, E-mail: briang@waikato.ac.nz; Yang, Fei; Raynova, Stella; Lu, Huiyang

    2016-07-25

    A trace amount of LaB{sub 6} powder was added to P/M Ti and Ti–6Al–4V alloy to improve mechanical properties and refine the microstructure. After sintering, TiB whiskers and La{sub 2}O{sub 3} dispersoids had formed in the microstructure. In a CP Ti alloy, the generation of secondary phases leads to a much refined microstructure, but the alignment of TiB whiskers led to a variation in mechanical properties. Open die forging (ODF) or powder compact extrusion (PCE) was carried out on sintered Ti–6Al–4V alloy to further improve the mechanical properties. This caused severe deformation and re-alignment of the TiB whiskers. Comparing the properties of hot worked Ti–6Al–4V alloy and Ti–6Al–4V alloy with boron additions, an addition of LaB{sub 6} leads to slightly lower strength but gives significant better ductility. - Highlights: • LaB{sub 6} powder was added to sintered and hot worked Ti and Ti–6Al–4V alloy. • TiB whiskers and La{sub 2}O{sub 3} dispersoids formed in the microstructure. • Different alignments of TiB{sub w} led to a variation in mechanical properties. • Hot working caused severe deformation and re-alignment of TiB{sub w}. • An addition of LaB{sub 6} is better than pure boron additions.

  20. Microstructural heterogeneities and fatigue anisotropy of forged steels

    International Nuclear Information System (INIS)

    Pessard, Etienne; Morel, Franck; Verdu, Catherine; Flaceliere, Laurent; Baudry, Gilles

    2011-01-01

    Highlights: → Tomography result: fibering is composed of non-metallic inclusions bands. → Elongated inclusions decreases the: ductility, fracture toughness and fatigue limit. → Cracks initiate from both inclusion clusters and from the bainitic matrix. → The classical self-heating method does not predict the effect of the inclusions. - Abstract: In this study, various experimental methods are employed to determine the anisotropic fatigue behavior of a 25MnCrSiVB6 forged steel (Metasco MC). This material has a bainitic microstructure and contains many elongated non-metallic inclusions in the rolled direction, which are grouped into clusters. Specimens with different orientations relative to the rolling direction have been extracted from a hot rolled bar and the ability of certain experimental techniques to capture the fatigue anisotropy has been tested. Results obtained from monotonic tensile tests and Charpy impact tests show that the material has isotropic fracture strength and anisotropic ductility. The influence of the 'inclusion clusters' is clearly demonstrated via observation of the fracture surfaces. Concerning the fatigue behavior, results from a classical staircase experimental procedure are compared to results from self-heating fatigue tests. For specimens orientated at 0 o relative to the rolled direction, microcrack initiation is controlled by the material matrix and the prediction of the fatigue strength with the self-heating method has been observed to be correct. For specimens orientated at 45 o and 90 o , the elongated manganese sulfide inclusion clusters are the origin of crack initiation and the fatigue strength drops significantly. For this case, it appears that the self-heating method has difficulty predicting the fatigue behavior.

  1. Numerical simulation of electric field assisted sintering

    Science.gov (United States)

    McWilliams, Brandon A.

    A fully coupled thermal-electric-sintering finite element model was developed and implemented to explore electric field assisted sintering techniques (FAST). FAST is a single step processing operation for producing bulk materials from powders, in which the powder is heated by the application of electric current under pressure. This process differs from other powder processing techniques such as hot isostatic pressing (HIP) and traditional press and sinter operations where the powder or compact is heated externally, in that the powder is heated directly as a result of internal Joule heating (for conductive powders) and/or by direct conduction from the die and punches. The overall result is much more efficient heating which allows heating rates of >1000°C/min to be achieved which is desirable for sintering bulk nanocrystalline and other novel high performance materials. Previous modeling efforts on FAST have only considered the thermal-electric aspect of the problem and have neglected densification. In addition to the introduction of a sintering model, a detailed thermal-electric study of process parameters was carried out in order to identify key system variables and quantify their effect on the overall system response and subsequent thermal history of a consolidated sample. This analysis was compared to empirical data from a parallel experimental study and shown to satisfactorily predict the observed trends. This model was then integrated with a phenomenologically based sintering model to capture the densification of the sample. This fully coupled model was used to predict densification kinetics under FAST like conditions and examine the evolution of material properties as the sample transitions from a loose powder to a fully dense compact and the resulting effect on the electrical and thermal fields within the compact. This model was also used to explore the effect of non-uniform thermal, electrical, stress and density fields on the final geometry and local

  2. New design of process for cold forging to improve multi-stage gas fitting

    Directory of Open Access Journals (Sweden)

    Han-Sung Huang

    2016-04-01

    Full Text Available This work develops a process that solves the problem of the formation of cracks inside forged gas fittings in the cold forging process that arises from poor forging process design. DEFORM-3D forming software was utilized, and macroscopic experiments with optical microscopy and scanning electron microscopy were conducted to investigate the processed structures and the distribution therein of metal flow lines, and to find the internal micro-cracks to determine whether the cold forging process is reasonable. Analytical results herein demonstrate that the stress and strain inside the gas fitting can be elucidated using metal forming software. Together with experimental results, they demonstrate that a concentration of stress damages the workpiece in the forming process. Moreover, as metal flow lines become narrower, the workpiece becomes more easily damaged. Consequently, the improved cold forging process that is described in this work should be utilized to reduce the occurrence of fine cracks and defects. Planning for proper die design and production, increasing the quality of products, and reducing the number of defective products promote industrial competitiveness.

  3. Numerical Simulation and Experimental Investigation on Multi-direction Forging Behaviors of High Purity Aluminum

    Directory of Open Access Journals (Sweden)

    ZHU Qing-feng

    2017-04-01

    Full Text Available The effect of forging pass on the deformation structure of high purity aluminum at room temperature during multi-direction forging process was investigated by experiment. The multi-direction forging process was analyzed by using software of DEFORM-3D. The results show that an X-shape fine grain zone (in the center of the sample and four coarse grain zones (near the end surface of the sample are initially formed on the cross section of the sample as forging passes increase to 3. With a further increasing the passes to 9, this X-shape zone tends to spread the whole sample. However, the grain difference between the coarse grain zone and fine grain zone still exists on the sample forged by 9 passes. Limitation in the structural refinement is observed in the center of the sample with the increment of equivalent strain. The grains size in the center is refined to a certain size (about 70μm as equivalent strain reaches 2.5, and no further grain refinement in the center with increasing the equivalent strain to 6.0. However, the grains size in the area near the surface is continuously refined with the increasing the equivalent strain to 4.0. This indicates that the local deformation state and the equivalent strain are two important factors that affect the grain size.

  4. Multiobjective Optimization of Precision Forging Process Parameters Based on Response Surface Method

    Directory of Open Access Journals (Sweden)

    Fayuan Zhu

    2015-01-01

    Full Text Available In order to control the precision forging forming quality and improve the service life of die, a multiobjective optimization method for process parameters design was presented by applying Latin hypercube design method and response surface model approach. Meanwhile the deformation homogeneity and material damage of forging parts were proposed for evaluating the forming quality. The forming load of die was proposed for evaluating the service life of die. Then as a case of study, the radial precision forging for a hollow shaft with variable cross section and wall thickness was carried out. The 3D rigid-plastic finite element (FE model of the hollow shaft radial precision forging was established. The multiobjective optimization forecast model was established by adopting finite element results and response surface methodology. Nondominated sorting genetic algorithm-II (NSGA-II was adopted to obtain the Pareto-optimal solutions. A compromise solution was selected from the Pareto solutions by using the mapping method. In the finite element study on the forming quality of forging parts and the service life of dies by multiobjective optimization process parameters, the feasibility of the multiobjective optimization method presented by this work was verified.

  5. Test report: effect of specimen orientation and location on the tensile properties of GTS forging 1472859

    Energy Technology Data Exchange (ETDEWEB)

    Melcher, Ryan J [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2008-02-12

    ASTM standardized tensile tests were performed on GTS WR-quality 1472859 forging (21-6- 9 material) to determine the dependence of tensile properties on specimen orientation (longitudinal vs. transverse) with respect to forging ‘grain flow’ and location within the forging. Statistical analyses of the results show that location has a statistically measurable effect on the longitudinal tensile properties (as compared to the error involved in tensile testing). However, this dependence of the properties with location, especially in the circumferential orientation, causes large variability in the results that clouds the statistical determination of any orientation effect. As a result, this forging is determined to be inhomogeneous along the forging length, with a significant range in properties observed (e.g. yield strengths from 85 to 117 ksi) and highest strength/lowest ductility in the spherical region. Additional specimens should be tested to acquire a higher resolution view of this inhomogeneity if the end use of the data is structural integrity analyses using spatially dependent properties; however, sufficient data is provided in this study to extract a statistical lower bound for conservative, homogeneous structural analysis.

  6. Influence of the Constitutive Flow Law in FEM Simulation of the Radial Forging Process

    Directory of Open Access Journals (Sweden)

    Olivier Pantalé

    2013-01-01

    Full Text Available Radial forging is a widely used forming process for manufacturing hollow products in transport industry. As the deformation of the workpiece, during the process, is a consequence of a large number of high-speed strokes, the Johnson-Cook constitutive law (taking into account the strain rate seems to be well adapted for representing the material behavior even if the process is performed under cold conditions. But numerous contributions concerning radial forging analysis, in the literature, are based on a simple elastic-plastic formulation. As far as we know, this assumption has yet not been validated for the radial forging process. Because of the importance of the flow law in the effectiveness of the model, our purpose in this paper is to analyze the influence of the use of an elastic-viscoplastic formulation instead of an elastic-plastic one for modeling the cold radial forging process. In this paper we have selected two different laws for the simulations: the Johnson-Cook and the Ludwik ones, and we have compared the results in terms of forging force, product's thickness, strains, stresses, and CPU time. For the presented study we use an AISI 4140 steel, and we denote a fairly good agreement between the results obtained using both laws.

  7. Identification of forged Bank of England £20 banknotes using IR spectroscopy

    Science.gov (United States)

    Sonnex, Emily; Almond, Matthew J.; Baum, John V.; Bond, John W.

    2014-01-01

    Bank of England notes of £20 denomination have been studied using infrared spectroscopy in order to generate a method to identify forged notes. An aim of this work was to develop a non-destructive method so that a small, compact Fourier transform infrared spectrometer (FT-IR) instrument could be used by bank workers, police departments or others such as shop assistants to identify forged notes in a non-lab setting. The ease of use of the instrument is the key to this method, as well as the relatively low cost. The presence of a peak at 1400 cm-1 arising from νasym (CO32-) from the blank paper section of a forged note proved to be a successful indicator of the note's illegality for the notes that we studied. Moreover, differences between the spectra of forged and genuine £20 notes were observed in the ν(OH) (ca. 3500 cm-1), ν(Csbnd H) (ca. 2900 cm-1) and ν(Cdbnd O) (ca. 1750 cm-1) regions of the IR spectrum recorded for the polymer film covering the holographic strip. In cases where these simple tests fail, we have shown how an infrared microscope can be used to further differentiate genuine and forged banknotes by producing infrared maps of selected areas of the note contrasting inks with background paper.

  8. Identification of Forged Bank of England 20 Gbp Banknotes Using IR Spectroscopy

    Science.gov (United States)

    Sonnex, Emily

    2014-06-01

    Bank of England notes of 20 GBP denomination have been studied using infrared spectroscopy in order to generate a method to identify forged notes. A principal aim of this work was to develop a method so that a small, compact ATR FTIR instrument could be used by bank workers, police departments or others such as shop assistants to identify forged notes in a non-lab setting. The ease of use of the instrument is the key to this method, as well as the relatively low cost. The presence of a peak at 1400 wn from the blank paper section of a forged note proved to be a successful indicator of the note's illegality for the notes that we studied. Moreover, differences between the spectra of forged and genuine 20 GBP notes were observed in the ν(OH) (ca. 3500 wn), ν(C-H) (ca. 2900 wn) and ν(C=O) (ca. 1750 wn) regions of the IR spectrum recorded for the polymer film covering the holographic strip. In cases where these simple tests fail, we have shown how an infrared microscope can be used to further differentiate genuine and forged banknotes by producing infrared maps of selected areas of the note contrasting inks with background paper. Further to this, with an announcement by the Bank of England to produce polymer banknotes in the future, the work has been extended using Australian polymer banknotes to show that the method would be transferable.

  9. Manufacturing of Nanostructured Rings from Previously ECAE-Processed AA5083 Alloy by Isothermal Forging

    Directory of Open Access Journals (Sweden)

    C. J. Luis

    2013-01-01

    Full Text Available The manufacturing of a functional hollow mechanical element or ring of the AA5083 alloy previously equal channel angular extrusion (ECAE processed, which presents a submicrometric microstructure, is dealt with. For this purpose, the design of two isothermal forging dies (preform and final shape is carried out using the design of experiments (DOE methodology. Moreover, after manufacturing the dies and carrying out tests so as to achieve real rings, the mechanical properties of these rings are analysed as well as their microstructure. Furthermore, a comparison between the different forged rings is made from ECAE-processed material subjected to different heat treatments, previous to the forging stage. On the other hand, the ring forging process is modelled through the use of finite element simulation in order to improve the die design and to study the force required for the isothermal forging, the damage value, and the strain the material predeformed by ECAE has undergone. With this present research work, it is intended to improve the knowledge about the mechanical properties of nanostructured material and the applicability of this material to industrial processes that allow the manufacturing of functional parts.

  10. Reheating of zinc-titanate sintered specimens

    Directory of Open Access Journals (Sweden)

    Labus N.

    2015-01-01

    Full Text Available The scope of this work was observing dimensional and heat transfer changes in ZnTiO3 samples during heating in nitrogen and air atmosphere. Interactions of bulk specimens with gaseous surrounding induce microstructure changes during heating. Sintered ZnTiO3 nanopowder samples were submitted to subsequent heating. Dilatation curves and thermogravimetric with simultaneous differential thermal analysis TGA/DTA curves were recorded. Reheating was performed in air and nitrogen atmospheres. Reheated samples obtained at different characteristic temperatures in air were analyzed by X-ray diffraction (XRD. Microstructures obtained by scanning electron microscopy (SEM of reheated sintered samples are presented and compared. Reheating in a different atmosphere induced different microstructures. The goal was indicating possible causes leading to the microstructure changes. [Projekat Ministarstva nauke Republike Srbije, br. OI172057 i br. III45014

  11. Foaming Glass Using High Pressure Sintering

    DEFF Research Database (Denmark)

    Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

    Foam glass is a high added value product which contributes to waste recycling and energy efficiency through heat insulation. The foaming can be initiated by a chemical or physical process. Chemical foaming with aid of a foaming agent is the dominant industrial process. Physical foaming has two...... variations. One way is by saturation of glass melts with gas. The other involves sintering of powdered glass under a high gas pressure resulting in glass pellets with high pressure bubbles entrapped. Reheating the glass pellets above the glass transition temperature under ambient pressure allows the bubbles...... to expand. After heat-treatment foam glass can be obtained with porosities of 80–90 %. In this study we conduct physical foaming of cathode ray tube (CRT) panel glass by sintering under high pressure (5-25 MPa) using helium, nitrogen, or argon at 640 °C (~108 Pa s). Reheating a sample in a heating...

  12. Sintering techniques for microstructure control in ceramics

    Science.gov (United States)

    Rosenberger, Andrew T.

    Sintering techniques can be manipulated to enhance densification in difficult to sinter materials and to produce property enhancing microstructures. However, the interplay between materials, sintering techniques, and end properties is not fully understood in many material systems, and some fundamental aspects of sintering such as the nature of the effects of electric fields remains unknown. The processing property relationships were examined in two classes of materials; zirconium diboride ultra high temperature ceramic composites, and all solid lithium-ion battery phosphate materials. Investigation of zirconium diboride ceramics focused on the effects of zirconium carbide as a secondary or tertiary phase in ZrB2 and ZrB2 -- SiC. Addition of zirconium carbide was observed to increase flexural strength of composites up to 590MPa at 50wt% ZrC, significantly higher than the flexural strength of 380MPa observed in similarly prepared ZrB2 -- SiC. This difference was attributed to the absence of CTE mismatch induced residual stresses in the ZrB2 -- ZrC composites. A high temperature reaction between ZrB2 and TiC producing Zr1-xTixB2 -- ZrC composites was discovered and found to enhance densification while reducing the average grain size to as small as 1.4mum, lower than the starting powder size of 1.8mum. While a high flexural strength of 670MPa was observed, a strength dependence on the ZrC grain size indicative of CTE mismatch residual stresses was also seen. Finally, the oxidation and ablation resistance of ZrB2 -- ZrC -- SiC composites as a function of ZrC fraction and ZrC:SiC ratio was investigated. Above 5vol% ZrC, the oxidation and ablation resistance of the composites was significantly reduced due to ZrC oxidation, regardless of SiC content. While ZrC can significantly enhance the mechanical properties of the composite, the volume fraction must be kept low to avoid an undesirable reduction in the oxidation resistance. The influence of applied electrical fields

  13. Reaction sintering of ceramic-metal composites

    International Nuclear Information System (INIS)

    Botta Filho, W.J.; Rodrigues, J.A.; Tomasi, R.; Pandolfelli, V.C.; Passos, J.F.S.S.; Folgueras, M.V.

    1990-01-01

    Reaction sintering experiments have been carried out in the system Al 2 O 3 -ZrAl 2 -Nb 2 O 5 with the objective of producing ceramic-metal composites of improved toughness. The sintering treatments have been done in the temperature range of 700 0 C to 1400 0 C under different conditions of vacuum and in air and argon atmospheres. The treated samples have been analysed by X-ray diffraction and analytical electron microscopy. The results are discussed in function of the degree of reaction, the development of microstructure and the densification. These results have shown that although an exchange reaction can occur to produce a composite, the control of the reaction to obtain a dense microstructure has not been possible yet. (author) [pt

  14. Sintering Behavior, Microstructure, and Mechanical Properties: A Comparison among Pressureless Sintered Ultra-Refractory Carbides

    Directory of Open Access Journals (Sweden)

    Laura Silvestroni

    2010-01-01

    Full Text Available Nearly fully dense carbides of zirconium, hafnium, and tantalum were obtained by pressureless sintering at 1950°C with the addition of 5–20 vol% of MoSi2. Increasing the amount of sintering aid, the final density increased too, thanks to the formation of small amounts of liquid phase constituted by M-Mo-Si-O-C, where M is either Zr, Hf, or Ta. The matrices of the composites obtained with the standard procedure showed faceted squared grains; when an ultrasonication step was introduced in the powder treatment, the grains were more rounded and no exaggerated grains growth occurred. Other secondary phases observed in the microstructure were SiC and mixed silicides of the transition metals. Among the three carbides prepared by pressurless sintering, TaC-based composites had the highest mechanical properties at room temperature (strength 590 MPa, Young's modulus 480 GPa, toughness 3.8 MPa·m1/2. HfC-based materials showed the highest sinterability (in terms of final density versus amount of sintering aid and the highest high-temperature strength (300 MPa at 1500  °C.

  15. Fabrication of Sintered Annular Fuel Pellet

    International Nuclear Information System (INIS)

    Rhee, Young Woo; Kim, Dong Joo; Kim, Jong Hun; Yang, Jae Ho; Kim, Keon Sik; Kang, Ki Won; Song, Kun Woo

    2010-01-01

    A dual cooled annular fuel has been seriously considered as a favorable option for uprating the power density of a Pressurized Water Reactor fuel assembly. An annular fuel has a geometrically inherent advantage such as an increased heat transfer area and a thin pellet thickness. It results in a lot of advantages from the point of a fuel safety and its economy. In order to actualize the dual cooled fuel, an essential element is the annular pellet with precisely controlled diametric tolerance. However, the unique shape of annular fuel pellet causes challenging difficulties to satisfy a diametric tolerance specification. Because of an inhomogeneous green density distribution along the compact height, an hour-glassing usually occurred in a sintered cylindrical PWR fuel pellet fabricated by a conventional doubleacting press. Thus, a sintered pellet usually undergoes a centerless grinding process in order to secure a pellet's specifications. In the case of an annular pellet fabrication using a conventional double-acting press, the same hour-glass shape would probably occur. The outer diameter tolerance of an annular pellet can be controlled easily similar to that of a conventional cylindrical PWR pellet through a centerless grinding. However, it appears not to be simple in the case of an inner surface grinding. It would be the best way to satisfy the specifications for the inner diameter in an as-fabricated pellet. In the present study, we are trying to find a way to minimize the diametric tolerance of the sintered annular pellet without inner surface grinding. This paper deals with a new approach that we have tried to reduce the diametric tolerance of the sintered annular pellet

  16. Sintering of titanium alloy by powder metallurgy

    Energy Technology Data Exchange (ETDEWEB)

    Cosme, C.R.M. [Universidade de Brasilia (UnB), DF (Brazil); Henriques, V.A.R.; Cairo, C.A.A.; Taddei, E.B. [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil)

    2009-07-01

    Full text: Titanium alloys are suitable for biomaterial applications, considering its biocompatibility and low elastic modulus compared to steel. Bone resorption in this case can be reduced by load sharing between the implant and natural bone.Starting powders were obtained by hydride method, carried out under positive hydrogen pressure at 500 deg C for titanium and 800 deg C for Nb, Zr and Ta powders. After reaching the nominal temperature, the material was held for 3h, with subsequent cooling to room temperature and milling of the friable hydride. Samples were produce by mixing of initial metallic powders followed by and cold isostatic pressing. Subsequent densification by sintering was performed at temperature range between 900 and 1700 deg C. Characterization was carried out with scanning electron microscopy, X-ray diffractometry and microhardness measurements. Microstructural examinations revealed higher amount of &⧣946;-phase for higher sintering temperature and dissolution of Ta and NB particles. In vitro tests revealed low cytotoxicity of sintered samples. (author)

  17. Sintering and deformation of nanocrystalline ceramics

    International Nuclear Information System (INIS)

    Hahn, H.; Averback, R.S.; Hofler, H.J.; Logas, J.

    1991-01-01

    Nanocrystalline ceramics have been produced by the method of inert gas condensation of ultra-small particles and in situ consolidation. Sintering characteristics and microstructural parameter such as grain size, porosity and pore size distributions have been investigated by a variety of techniques, including: X-ray diffraction, gravimetry, nitrogen adsorption, scanning electron microscopy and small angle neutron scattering. In pure TiO 2 , the sintering temperatures are drastically lowered compared to conventional ceramics, however, extensive grain growth occurs before full densification is achieved. High density, nanocrystalline ceramics can be prepared by pressure assisted sintering, doping and additions of second phases. High temperature microhardness and creep deformation in compression were measured and it was found that creep processes occur at lower temperatures than in ceramics with larger grain sizes. Nanocrystalline TiO 2 with densities >99% can be deformed plastically without fracture at temperatures below half the melting point. The total strains exceed 0.6 at strain rates as high as 10 -3 s -l . The stress exponent of the strain rate, n, is approximately 3 and the grain size dependence is G -q with q in the range of 1-1.5. In this paper it is concluded that the creep deformation occurs by an interface reaction controlled mechanism

  18. Numerical simulation of the dynamic recrystallization behaviour in hot precision forging helical gears

    Directory of Open Access Journals (Sweden)

    Feng Wei

    2015-01-01

    Full Text Available In hot precision forging helical gears, the dynamic recrystallization phenomena will occur, which affect the microstructure of the formed part and in turn decide their mechanical properties. To investigate the effect of deformation temperature on the dynamic recrystallization in hot precision forging helical gears, a three dimensional (3D finite element (FE model was created by coupling the thermo-mechanical model with the microstructure evolution model developed based on the hot compressive experimental data of 20CrMnTiH steel. The hot precision forging process was simulated and the effect laws of the deformation temperature on the microstructure evolution the formed part were investigated. The results show that the dynamic recrystallization volume fraction and the average grain sizes increased with the increasing deformation temperature and the higher deformation temperature is beneficial to dynamic recrystallization and grain refinement.

  19. The Investigations of Friction under Die Surface Vibration in Cold Forging Process

    DEFF Research Database (Denmark)

    Jinming, Sha

    of the application of ultrasonic vibration on drawing, rolling and other metal forming process show that the load and friction coefficient would be decreased with the presence of ultrasonic vibration. Investigations on forging processes and under low frequency, especially the quantitative analysis of friction......The objective of this thesis is to fundamentally study the influence of die surface vibration on friction under low frequency in metal forging processes. The research includes vibrating tool system design for metal forming, theoretical and experimental investigations, and finite element simulations...... on die surface vibration in forging process. After a general introduction to friction mechanisms and friction test techniques in metal forming, the application of ultrasonic vibration in metal forming, the influence of sliding velocity on friction is described. Some earlier investigations...

  20. Effects of Forging Stream Line on Tensile Strength Using FEM Simulation

    Directory of Open Access Journals (Sweden)

    Ching-Wei Shih

    2014-03-01

    Full Text Available Because bolt usages always have the requirement of tensile strength, with a view to reach the requirement of tensile strength, the material property or forming method and dies design can be used to obtain it. The study aims at the forming method and dies design to perform the multistage analysis of bolt to realize the effect of forging stream line continuity on tensile strength. The study uses Simufact-FEM software to do the multistage forming simulation to modify the dies design and forming method. The amount of broken forging stream line can be used to identify whether the bolt is good or not. From the comparison of realistic forging product, the results can verify the acceptance of FEM simulation.

  1. A two-step superplastic forging forming of semi-continuously cast AZ70 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Pan Wang

    2015-03-01

    Full Text Available A two-step technology combined forging with superplastic forming has been developed to enhance the forgeability of semi-continuously cast AZ70 magnesium alloy and realize the application of the as-cast magnesium alloy in large deformation bullet shell. In the first step, fine-grained microstructure preforms that are suitable for superplastic forming were obtained by reasonably designing the size of the initial blanks with the specific height-to-diameter ratio, upsetting the blanks and subsequent annealing. In the second step, the heat treated preforms were forged into the end products at the superplastic conditions. The end products exhibit high quality surface and satisfied microstructure. Consequently, this forming technology that not only avoids complicating the material preparation but also utilizes higher strain rate superplastic provides a near net-shaped novel method on magnesium forging forming technology using as-cast billet.

  2. What history reveals about Forge River pollution on Long Island, New York's south shore.

    Science.gov (United States)

    Swanson, R Lawrence; Brownawell, B; Wilson, Robert E; O'Connell, Christine

    2010-06-01

    Fifty years ago, the Forge River and Moriches Bay, of Long Island's south shore lagoonal system, achieved notoriety when their polluted conditions were alluded to in a report of the US President's Science Advisory Committee (1965). The Woods Hole Oceanographic Institution investigated the bay throughout the 1950s, identifying duck farming as the cause of "objectionable", "highly contaminated" conditions of these waters. Much has changed: duck farming declined; the river was dredged to remove polluted sediments, improve navigation; and barrier island inlets stabilized. Yet, the river remains seasonally eutrophic. Why? This paper reviews what occurred in the Forge River watershed. While governments aggressively curtailed the impacts of duck pollution, they failed to manage development and sewage pollution. The Forge experience indicates that watershed management is a continuing governmental responsibility as development accelerates. Otherwise, we will always be looking for that instantaneous remediation that is usually not affordable and is socially contentious.

  3. Process routes for die forging of hybrid bevel gears and bearing bushings

    Science.gov (United States)

    Behrens, Bernd-Arno; Bouguecha, Anas; Frischkorn, Conrad; Huskic, Adis; Chugreeva, Anna

    2017-10-01

    This paper describes two process routes with focus on the die forging of coaxial hybrid workpieces. Using the example of two multi-material demonstrators, a bevel gear and a bearing bushing, two fundamental principles of hybrid-forged components will be presented. A cost-effective construction is realized for the bevel gear by means of a high-strength steel combined with a low-cost steel in the areas where high strength is not required. In contrast, the bearing bushing consisting of a steel-aluminium combination offers new potentials in terms of lightweight construction, saving component weight while featuring equal durability. In addition, forging tooling systems and tailored heating strategies for both demonstrators are presented and discussed.

  4. Basic characteristics of Australian iron ore concentrate and its effects on sinter properties during the high-limonite sintering process

    Science.gov (United States)

    Liu, Dong-hui; Liu, Hao; Zhang, Jian-liang; Liu, Zheng-jian; Xue, Xun; Wang, Guang-wei; Kang, Qing-feng

    2017-09-01

    The basic characteristics of Australian iron ore concentrate (Ore-A) and its effects on sinter properties during a high-limonite sintering process were studied using micro-sinter and sinter pot methods. The results show that the Ore-A exhibits good granulation properties, strong liquid flow capability, high bonding phase strength and crystal strength, but poor assimilability. With increasing Ore-A ratio, the tumbler index and the reduction index (RI) of the sinter first increase and then decrease, whereas the softening interval (Δ T) and the softening start temperature ( T 10%) of the sinter exhibit the opposite behavior; the reduction degradation index (RDI+3.15) of the sinter increases linearly, but the sinter yield exhibits no obvious effects. With increasing Ore-A ratio, the distribution and crystallization of the minerals are improved, the main bonding phase first changes from silico-ferrite of calcium and aluminum (SFCA) to kirschsteinite, silicate, and SFCA and then transforms to 2CaO·SiO2 and SFCA. Given the utilization of Ore-A and the improvement of the sinter properties, the Ore-A ratio in the high-limonite sintering process is suggested to be controlled at approximately 6wt%.

  5. Mechanical properties and thermal shock performance of W-Y2O3 composite prepared by high-energy-rate forging

    Science.gov (United States)

    Lian, Youyun; Liu, Xiang; Feng, Fan; Song, Jiupeng; Yan, Binyou; Wang, Yingmin; Wang, Jianbao; Chen, Jiming

    2017-12-01

    The effects of the addition of Y2O3 and hot-deformation on the mechanical properties of tungsten (W) have been studied. The processing route comprises a doping technique for the distribution of Y2O3 particles in a tungsten matrix, conventional sintering in a hydrogen environment, and high-energy-rate forging (HERF). The microstructure of the composite was characterized by using transmission electron microscopy and electron backscattering diffraction imaging technique, and its mechanical properties were studied by means of tensile testing. The thermal shock response of the HERF processed W-Y2O3 was evaluated by applying edge-localized mode-like loads (100 pulses) with a pulse duration of 1 ms and an absorbed power density of up to 1 GW m‑2 at various temperatures between room temperature and 200 °C. HERF processing has produced elongated W grains with preferred orientations and a high density of structure defects in the composite. The composite material exhibits high tensile strength and good ductility, and a thermal shock cracking threshold lower than 100 °C.

  6. Co-Sintering behaviour of zirconia-ferritic steel composites

    Directory of Open Access Journals (Sweden)

    Alexander Michaelis

    2016-08-01

    Full Text Available The combination of metallic and ceramic materials allows the combination of positive properties of both and can be applied in various industrial fields. At the moment, the deployment of these composites faces difficult and complex manufacturing. One attempt, which offers a short process route and a high degree of flexibility regarding design is a combined shaping (co-shaping with a combined sintering (co-sintering. The article will show co-sintering results of different metal-ceramic symmetric and asymmetric multi-layered tapes, consisting of yttria stabilized zirconia combined with a ferritic iron chromium steel. Focus is on the densification and co-sintering behaviour of ceramic layers depending on the sintering behaviour of metallic layers. Co-sintered composites were characterized by field emission scanning electron microscopy, x-ray diffraction measurements and in terms of adhesive tensile strength.

  7. The development of reactor vessel internal heavy forging for 1000 MW pressurized-water reactor nuclear power plant

    International Nuclear Information System (INIS)

    Zhang Zhifeng; Chen Yongbo; Ding Xiuping; Zhang Lingfang

    2012-01-01

    This Paper introduced the development of Reactor Vessel Internal (RVI) heavy forgings for 1000 MW Pressurized Water Reactor (PWR) nuclear power plant, analyzed the manufacture difficulties and technical countermeasures. The testing result of the product indicated that the performance of RVI heavy forgings manufactured by Shanghai Heavy Machinery Plant Ld. (SHMP) is outstanding and entirely satisfy the technical requirements for RVI product. (authors)

  8. A friction model for cold forging of aluminum, steel and stainless steel provided with conversion coating and solid film lubricant

    DEFF Research Database (Denmark)

    Bay, Niels; Eriksen, Morten; Tan, Xincai

    2011-01-01

    Adopting a simulative tribology test system for cold forging the friction stress for aluminum, steel and stainless steel provided with typical lubricants for cold forging has been determined for varying normal pressure, surface expansion, sliding length and tool/work piece interface temperature...

  9. 31 CFR 370.40 - Can I be held accountable if my negligence contributes to a forged signature?

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Can I be held accountable if my negligence contributes to a forged signature? 370.40 Section 370.40 Money and Finance: Treasury Regulations... if my negligence contributes to a forged signature? (a) General. If your failure to exercise ordinary...

  10. 76 FR 52313 - Heavy Forged Hand Tools (i.e., Axes & Adzes, Bars & Wedges, Hammers & Sledges, and Picks...

    Science.gov (United States)

    2011-08-22

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-803] Heavy Forged Hand Tools (i.e... Administration, Department of Commerce. SUMMARY: As a result of the determinations by the Department of Commerce... on heavy forged hand tools (i.e., [[Page 52314

  11. Medium carbon vanadium steels for closed die forging; Acos de medio carbono microligados ao vanadio para forjaria em matriz fechada

    Energy Technology Data Exchange (ETDEWEB)

    Jeszensky, Gabor; Plaut, Ronald Lesley

    1993-12-31

    This work analyses the medium carbon micro alloyed vanadium potential for closed die forged production. The steels reach the mechanical resistance requests during cooling after forging, eliminating the subsequent thermal treatment. Those steels also present good fatigue resistance and machinability. The industrial scale experiments are also reported 16 refs., 21 figs.

  12. Manufacturing techniques and material properties of forged integral closure head for PWRRV

    International Nuclear Information System (INIS)

    Kataoka, Hideo; Kutomi, Yasuhiro; Iwamura, Toshihiko; Kawaguchi, Seiichi; Nagasako, Hiroyuki; Funakoshi, Yoshihiko; Tokuno, Katsuhiko.

    1997-01-01

    A prototype forged integral closure head for PWR Reactor Vessels was manufactured, and evaluation tests on material properties were carried out in order to verify that an integral closure head for nuclear use can be manufactured. As a result of this work, the key techniques and quality assurance activities on the manufacturing of an integral closure head were verified and the reliability of the material properties was confirmed. Based on these results, the integral closure head was applied to the Reactor Vessel head replacement of Takahama Unit No.2 Nuclear Power Plant. This paper describes the manufacturing techniques and material properties of the forged integral closure head for PWR Reactor Vessels. (author)

  13. Study on antioxidant experiment on forged steel tube sheet and tube hole for steam generator

    International Nuclear Information System (INIS)

    Zong Hai; Wang Detai; Ding Yang

    2012-01-01

    Antioxidant experiment on forged steel tube sheet and tube hole for steam generator was studied and the influence of different simulated heat treatments on the antioxidant performance of tube sheet and tube hole was made. The influence of different antioxidant methods on the size of tube hole was drawn. Furthermore, the change of size and weight of 18MnD5 forged steel tube sheet on the condition of different simulated heat treatments was also studied. The analytical results have proved reference information for the use of 18MnD5 material and for key processes of processing tube hole and wearing and expanding U-style tube. (authors)

  14. Application of directional solidification ingot (LSD) in forging of PWR reactor vessel heads

    International Nuclear Information System (INIS)

    Benhamou, C.; Poitrault, I.

    1985-09-01

    Creusot-Loire Industrie uses this type of ingot for manufacture of Framatome 1300 and 1450 MW 4-loop PWR reactor vessel heads. This type of ingot offers a number advantages: improved internal soundness; greater chemical, structural and mechanical homogeneity of the finished part; simplified forging process. After a brief description of the pouring and solidification processes, this paper presents an analysis of the results of examinations performed on the prototype forging, as well as review of results obtained during industrial fabrication of dished heads from LSD ingots. The advantages of the LSD ingot over conventional ingots are discussed in conclusion

  15. On evaluating the quality of the rotor forgings of steam-turbine generators

    International Nuclear Information System (INIS)

    Yamaya, Yoshiyuki

    1978-01-01

    With rapid advances in manufacturing technology, it has become possible to produce rotor forgings of high quality and prodigious size for steam-turbine generators. In terms of quality, emphasis falls specifically on two points-increased toughness and reduction of internal flaws. The article gives an overview of the present situation regarding forging quality; on the subject of actual sand-inclusion flaws, it presents an example of an evaluation and describes an improved method of ultrasonic inspection using crescent-shaped grooves. (auth.)

  16. Reactive Sintering of Bimodal WC-Co Hardmetals

    OpenAIRE

    Marek Tarraste; Kristjan Juhani; Jüri Pirso; Mart Viljus

    2015-01-01

    Bimodal WC-Co hardmetals were produced using novel technology - reactive sintering. Milled and activated tungsten and graphite powders were mixed with commercial coarse grained WC-Co powder and then sintered. The microstructure of produced materials was free of defects and consisted of evenly distributed coarse and fine tungsten carbide grains in cobalt binder. The microstructure, hardness and fracture toughness of reactive sintered bimodal WC-Co hardmetals is exhibited. Developed bimodal har...

  17. Sintering of Lead-Free Piezoelectric Sodium Potassium Niobate Ceramics

    Directory of Open Access Journals (Sweden)

    Barbara Malič

    2015-12-01

    Full Text Available The potassium sodium niobate, K0.5Na0.5NbO3, solid solution (KNN is considered as one of the most promising, environment-friendly, lead-free candidates to replace highly efficient, lead-based piezoelectrics. Since the first reports of KNN, it has been recognized that obtaining phase-pure materials with a high density and a uniform, fine-grained microstructure is a major challenge. For this reason the present paper reviews the different methods for consolidating KNN ceramics. The difficulties involved in the solid-state synthesis of KNN powder, i.e., obtaining phase purity, the stoichiometry of the perovskite phase, and the chemical homogeneity, are discussed. The solid-state sintering of stoichiometric KNN is characterized by poor densification and an extremely narrow sintering-temperature range, which is close to the solidus temperature. A study of the initial sintering stage revealed that coarsening of the microstructure without densification contributes to a reduction of the driving force for sintering. The influences of the (K + Na/Nb molar ratio, the presence of a liquid phase, chemical modifications (doping, complex solid solutions and different atmospheres (i.e., defect chemistry on the sintering are discussed. Special sintering techniques, such as pressure-assisted sintering and spark-plasma sintering, can be effective methods for enhancing the density of KNN ceramics. The sintering behavior of KNN is compared to that of a representative piezoelectric lead zirconate titanate (PZT.

  18. Sintering of Lead-Free Piezoelectric Sodium Potassium Niobate Ceramics

    Science.gov (United States)

    Malič, Barbara; Koruza, Jurij; Hreščak, Jitka; Bernard, Janez; Wang, Ke; Fisher, John G.; Benčan, Andreja

    2015-01-01

    The potassium sodium niobate, K0.5Na0.5NbO3, solid solution (KNN) is considered as one of the most promising, environment-friendly, lead-free candidates to replace highly efficient, lead-based piezoelectrics. Since the first reports of KNN, it has been recognized that obtaining phase-pure materials with a high density and a uniform, fine-grained microstructure is a major challenge. For this reason the present paper reviews the different methods for consolidating KNN ceramics. The difficulties involved in the solid-state synthesis of KNN powder, i.e., obtaining phase purity, the stoichiometry of the perovskite phase, and the chemical homogeneity, are discussed. The solid-state sintering of stoichiometric KNN is characterized by poor densification and an extremely narrow sintering-temperature range, which is close to the solidus temperature. A study of the initial sintering stage revealed that coarsening of the microstructure without densification contributes to a reduction of the driving force for sintering. The influences of the (K + Na)/Nb molar ratio, the presence of a liquid phase, chemical modifications (doping, complex solid solutions) and different atmospheres (i.e., defect chemistry) on the sintering are discussed. Special sintering techniques, such as pressure-assisted sintering and spark-plasma sintering, can be effective methods for enhancing the density of KNN ceramics. The sintering behavior of KNN is compared to that of a representative piezoelectric lead zirconate titanate (PZT). PMID:28793702

  19. The electric conductivity of some forms of sintered synthetic zeolites

    International Nuclear Information System (INIS)

    Susic, M.; Petrovic, V.; Ristic, M.; Petranovic, N.

    1978-01-01

    Some forms of synthetic zeolites were sintered and their electric conductivity was measured. The conductivity was observed in correlation with the conductivity of non-sintered pressed samples. Also the change in microstructural constituents in the course of the process of sintering was observed with an optical microscope. It has been found that there is a considerable change in conductivity due to sintering as well as a change in the activation energy for conduction. Also the porosity is noticeably changed. A marked affect of the nature of counter ions on the electric conductivity is shown

  20. Sintering, microstructural and dilatometric studies of combustion synthesized Synroc phases

    International Nuclear Information System (INIS)

    Muthuraman, M.; Patil, K.C.; Senbagaraman, S.; Umarji, A.M.

    1996-01-01

    Sintering, microstructure, and linear thermal expansion properties of Synroc-B and constituent phases, viz. perovskite CaTiO 3 , zirconolite ZrTi 2 O 7 , hollandite (ideal formula BaAl2Ti 6 O 16 ) have been investigated. Synroc-B powder when pelletized and sintered at 1250 C for 2 h achieved >95% theoretical density. Sintered Synroc-B has a linear thermal expansion coefficient α of 8.72 x 10 -6 K -1 and Vicker's microhardness 9.88 GPa. The linear thermal expansion curves did not show any hysteresis indicating the absence of microcracking in the sintered bodies

  1. Rapid laser sintering of metal nano-particles inks.

    Science.gov (United States)

    Ermak, Oleg; Zenou, Michael; Toker, Gil Bernstein; Ankri, Jonathan; Shacham-Diamand, Yosi; Kotler, Zvi

    2016-09-23

    Fast sintering is of importance in additive metallization processes and especially on sensitive substrates. This work explores the mechanisms which set limits to the laser sintering rate of metal nano-particle inks. A comparison of sintering behavior of three different ink compositions with laser exposure times from micro-seconds to seconds reveals the dominant factor to be the organic content (OC) in the ink. With a low OC silver ink, of 2% only, sintering time falls below 100 μs with resistivity <×4 bulk silver. Still shorter exposure times result in line delamination and deformation with a similar outcome when the OC is increased.

  2. Interpretation of Frenkel’s theory of sintering considering evolution of activated pores: III. Determination of equilibrium sintering time

    Directory of Open Access Journals (Sweden)

    Yu C.L.

    2015-01-01

    Full Text Available In this article, the Frenkel’s theory of liquid-phase sintering was interpreted regarding pores as the activated volume. The mathematical model established by Nikolić et al. was used to infer the equilibrium sintering time at varied sintering temperatures during the isothermal sintering of codierite glass by Giess et al. Through the calculation, the equilibrium time at 800ºC, 820ºC, 840ºC and 860ºC is inferred to be 7014.42mins, 1569.65mins, 368.92mins and 114.61mins, respectively. The equilibrium time decreases as the temperature increases. And the theoretical value is in good accordance with the experimental results. Thus, the model established by Nikolić et al. can be applied successfully to predict the equilibrium sintering time of the cordierite glass at varied temperatures during isothermal sintering.

  3. Residual stresses in a co-sintered SOC half-cell during post-sintering cooling

    DEFF Research Database (Denmark)

    Charlas, Benoit; Chatzichristodoulou, Christodoulos; Brodersen, Karen

    2014-01-01

    Due to the thermal expansion mismatch between the layers of a Solid Oxide Cell, residual stresses (thermal stresses) develop during the cooling after sintering. Residual stresses can induce cell curvature for asymmetric cells but more importantly they also result in more fragile cells. Depending...

  4. Powder densification maps in Selective Laser Sintering

    International Nuclear Information System (INIS)

    Bourell, D.; Wohlert, M.; Harlan, N.; Beaman, J.; Das, S.

    2002-01-01

    Selective Laser Sintering (SLS) is a manufacturing process in which a part is produced without the need for part-specific tooling. It competes effectively with other manufacturing processes when part geometry is complex and the production run is not large. Traditionally, this was limited to prototype production, although tooling applications are now appearing. This paper describes several applications of powder densification maps to advance solutions in direct SLS of metallic and ceramic powders. Time-dependent plasticity issues arise in pre-processing of powder to make it suitable for SLS and in post-processing of SLS parts to obtain desired density. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  5. Computer Modeling of Direct Metal Laser Sintering

    Science.gov (United States)

    Cross, Matthew

    2014-01-01

    A computational approach to modeling direct metal laser sintering (DMLS) additive manufacturing process is presented. The primary application of the model is for determining the temperature history of parts fabricated using DMLS to evaluate residual stresses found in finished pieces and to assess manufacturing process strategies to reduce part slumping. The model utilizes MSC SINDA as a heat transfer solver with imbedded FORTRAN computer code to direct laser motion, apply laser heating as a boundary condition, and simulate the addition of metal powder layers during part fabrication. Model results are compared to available data collected during in situ DMLS part manufacture.

  6. Selective laser sintering in biomedical engineering.

    Science.gov (United States)

    Mazzoli, Alida

    2013-03-01

    Selective laser sintering (SLS) is a solid freeform fabrication technique, developed by Carl Deckard for his master's thesis at the University of Texas, patented in 1989. SLS manufacturing is a technique that produces physical models through a selective solidification of a variety of fine powders. SLS technology is getting a great amount of attention in the clinical field. In this paper the characteristics features of SLS and the materials that have been developed for are reviewed together with a discussion on the principles of the above-mentioned manufacturing technique. The applications of SLS in tissue engineering, and at-large in the biomedical field, are reviewed and discussed.

  7. SEM hot stage sintering of UO2

    International Nuclear Information System (INIS)

    Miller, D.J.

    1976-06-01

    The sintering of hyperstoichiometric uranium dioxide powder compacts, in the hot stage of a scanning electron microscope, was continuously monitored using 16 mm time lapse movies. From alumina microspheres placed on the surface of the compacts, shrinkage measurements were obtained. Converting shrinkage measurements into densification profiles indicates that a maximum densification rate is reached at a critical density, independent of the constant heating rates. At temperatures above 1350 0 C, the movement of the reference microspheres made shrinkage measurements impossible. It is believed the evolution of UO 3 gas from hyperstoichiometric UO 2 is the cause of this limitation

  8. Characterization of Cracking and Crack Growth Properties of the C5A Aircraft Tie-Box Forging

    Science.gov (United States)

    Piascik, Robert S.; Smith, Stephen W.; Newman, John A.; Willard, Scott A.

    2003-01-01

    Detailed destructive examinations were conducted to characterize the integrity and material properties of two aluminum alloy (7075-T6) horizontal stabilizer tie box forgings removed.from US. Air Force C5A and C5B transport aircraft. The C5B tie box forging was,found to contain no evidence of cracking. Thirteen cracks were found in the CSA,forging. All but one of the cracks observed in the C5A component were located along the top cap region (one crack was located in the bottom cap region). The cracks in the C5A component initiated at fastener holes and propagated along a highly tunneled intergranular crack path. The tunneled crack growth configuration is a likelv result of surface compressive stress produced during peening of the .forging suijace. The tie box forging ,fatigue crack growth, fracture and stress corrosion cracking (SCC) properties were characterized. Reported herein are the results of laboratory air ,fatigue crack growth tests and 95% relative humidity SCC tests conducted using specimens machined from the C5A ,forging. SCC test results revealed that the C5A ,forging material was susceptible to intergranular environmental assisted cracking: the C5A forging material exhibited a SCC crack-tip stress-intensity factor threshold of less than 6 MPadn. Fracture toughness tests revealed that the C5A forging material exhibited a fracture toughness that was 25% less than the C5B forging. The C5A forging exhibited rapid laboratory air fatigue crack growth rates having a threshold crack-tip stress-intensity factor range of less than 0.8 MPa sup m. Detailed fractographic examinations revealed that the ,fatigue crack intergranular growth crack path was similar to the cracking observed in the C5A tie box forging. Because both fatigue crack propagation and SCC exhibit similar intergranular crack path behavior, the damage mechanism resulting in multi-site cracking of tie box forgings cannot be determined unless local cyclic stresses can be quantified.

  9. Modelling the void deformation and closure by hot forging of ingot castings

    DEFF Research Database (Denmark)

    Christiansen, Peter; Hattel, Jesper Henri; Kotas, Petr

    2012-01-01

    After solidification and cooling cast ingots contain voids due to improper feeding and volume shrinkage. Such voids are normally unwanted, so besides of forming the ingot to the desired shape, one of the purposes of the post processing of the ingot by hot forging is to close such voids by mechani...

  10. Path planning and kinematics simulation of surfacing cladding for hot forging die

    Directory of Open Access Journals (Sweden)

    Wang Huajun

    2015-01-01

    Full Text Available During the course of their work, a variety of damage and failure of hot forging die occurs and seriously affect the service life. Multi-layer metal hot forging die with functionally graded material structure can effectively extend the service life. In this paper, According to the needs of strengthening forging cavity, the CAD model of surfacing forming center was designed. Based on technological requirements of surface cladding for die cavity, the coupled movement equation of weld torch was established, and the trajectory of welding positioner and Cartesian robot kinematics was solved. The weld torch path was planned, according to the typical methods used in plane welding, and the surfacing path data was extracted by the secondary development of UG/OPEN. Then the kinematics solver program, which can output the control function of motion simulation, was written in MATLAB to solve the kinematics equation. Finally, in UG NX7.5, the kinematics simulation model was built to verify the correctness of mathematical model and the rationality of welding path planning. The above studies can provide a technical support for the die repair and manufacturing of a multilayer metal forging die.

  11. Strain Evolution in Cold-Warm Forged Steel Components Studied by Means of EBSD Technique.

    Science.gov (United States)

    Ferro, Paolo; Bonollo, Franco; Bassan, Fabio; Berto, Filippo

    2017-12-18

    Electron BackScatter Diffraction (EBSD) in conjunction with Field-Emission Environmental Scanning Electron Microscopy (FEG-ESEM) has been used to evaluate the microstructural and local plastic strain evolution in different alloys (AISI 1005, AISI 304L and Duplex 2205) deformed by a single-stage cold and warm forging process. The present work is aimed to describe the different behavior of the austenite and ferrite during plastic deformation as a function of different forging temperatures. Several topological EBSD maps have been measured on the deformed and undeformed states. Then, image quality factor, distributions of the grain size and misorientation have been analyzed in detail. In the austenitic stainless steel, the γ-phase has been found to harden more easily, then α-phase and γ-phase in AISI 1005 and in duplex stainless steel, sequentially. Compared to the high fraction of continuous dynamic recrystallized austenitic zones observed in stainless steels samples forged at low temperatures, the austenitic microstructure of samples forged at higher temperatures, 600-700 °C, has been found to be mainly characterized by large and elongated grains with some colonies of fine nearly-equiaxed grains attributed to discontinuous dynamic recrystallization.

  12. Preform design optimization for forging process based on the topological approach

    Science.gov (United States)

    Shao, Yong; Lu, Bin; Ou, Hengan; Cui, Zhenshan

    2013-05-01

    Preform design plays an important role in forging design especially for parts with complex shapes. In this paper, an attempt was made to develop a topological approach in the preform design of bulk metal forming processes based on the Bi-direction evolutionary structural optimization (BESO) strategy. In this approach, a new element addition and removal criteria based on the equivalent strain have been proposed for evaluating and optimizing the material flow in the forging process. To obtain a smooth preform boundary, a closed B-spline curve based on the least square approximation algorithm is employed to approximate the uneven surface of updated preform. An inhouse developed C♯ program has been employed to integrate the FE simluation, shape optimsation and surface approximation process. A 2D blade forging perform design problem are evaluate using the developed method. The results suggest that the optimized preform has shown better performance in improving the material flow and deformation uniformity during the forging. The results also demonstrate the robustness and efficiency of the developed preform design optimization method.

  13. Surface durability of powder-forged roller treated by shot peening

    International Nuclear Information System (INIS)

    Seki, Masanori; Fujii, Masahiro; Kobayashi, Yuji; Sato, Masaaki; Yoshida, Akira

    2010-01-01

    To investigate the influence of shot peening on the surface durability of powder-forged rollers, the case-hardened powder-forged rollers with a forging density of 7.5 g/cm 3 treated by the single shot peening and the double shot peening were fatigue-tested under a slidingrolling contact condition. The surface roughness, the surface hardness and the surface compressive residual stress of the rollers were increased by the shot peening. In addition, the pores near the roller surface were deformed by the shot peening. The failure mode of all the test rollers was spalling due to subsurface cracking. The fatigue lives of all the test rollers were improved by the shot peening, and that of the test roller S08, which was shot-peened with the hardest steel shots in this experimental range, was especially improved. The surface durability of the test roller S08 was also most improved by the shot peening. Cracks became difficult to occur and propagate under the roller surface since the pores near the roller surface were deformed by the stronger shot peening. In this study, double shot peening, which generally restrains the increase in surface roughness, was not particularly effective for the improvement in the surface durability of the powder-forged rollers, because the influence of tangential force on fatigue was not always great in a case of subsurface cracking

  14. The Ties That Bind: How Social Capital Is Forged and Forfeited in Teacher Communities

    Science.gov (United States)

    Bridwell-Mitchell, E. N.; Cooc, North

    2016-01-01

    The effects of social capital on school improvement make it important to understand how teachers forge, maintain, or forfeit collegial relationships. Two common explanations focused on formal organizational features and individual characteristics do not address how social capital accrues from informal dynamics of teachers' interactions in…

  15. Forgings made of austenitic chromium-nickel steels for the low temperature range

    International Nuclear Information System (INIS)

    Gruendler, O.; Schwarz, W.; Koren, M.

    1981-01-01

    The authors discuss the low temperature application of austenitic chromium-nickel steels for energy production and process techniques. Material requirements are presented, and the behaviour, mechanical and physical properties of such steels are discussed. The manufacture of forgings is considered and test results presented. (Auth.)

  16. Forgings made of austenitic chromium-nickel steels for the low temperature range

    Energy Technology Data Exchange (ETDEWEB)

    Gruendler, O.; Schwarz, W.; Koren, M. (Vereinigte Edelstahlwerke A.G. (VEW), Kapfenberg (Austria))

    1981-09-01

    The authors discuss the low temperature application of austenitic chromium-nickel steels for energy production and process techniques. Material requirements are presented, and the behaviour, mechanical and physical properties of such steels are discussed. The manufacture of forgings is considered and test results presented.

  17. A life study of ausforged, standard forged, and standard machined AISI M-50 spur gears

    Science.gov (United States)

    Townsend, D. P.; Zaretsky, E. V.; Bamberger, E. N.

    1975-01-01

    Tests were conducted at 350 K with three groups of 8.9 cm pitch diameter spur gears made of vacuum-induction melted (VIM), vacuum-arc remelted (VAR), AISI M-50 steel and one group of vacuum-arc remelted (VAR) AISI 9310 steel. The pitting fatigue life of the standard forged and ausforged gears was approximately five times that of the VAR AISI 9310 gears and ten times that of the bending fatigue life of the standard machined VIM-VAR AISI M-50 gears run under identical conditions. There was a slight decrease in the 10-percent life of the ausforged gears from that for the standard forged gears. However, the difference is not statistically significant. The standard machined gears failed primarily by gear tooth fracture while the forged and ausforged VIM-VAR AISI M-50 and the VAR AISI 9310 gears failed primarily by surface pitting fatigue. The ausforged gears had a slightly greater tendency to fail by tooth fracture than the standard forged gears.

  18. Influence of the hydrostatic stress component on critical surface expansion in forging compound products

    DEFF Research Database (Denmark)

    Vorm, T; Bay, Niels; Wanheim, Tarras

    1974-01-01

    of a superimposed hydrostatic pressure on the critical surface expansion during a forging process. The critical surface expansion appears to decrease with increasing hydrostatic pressure. This may be due to the fact that the close contact between the materials necessary to obtain bonding is created by a micro...

  19. Social Work and Engineering Collaboration: Forging Innovative Global Community Development Education

    Science.gov (United States)

    Gilbert, Dorie J.

    2014-01-01

    Interdisciplinary programs in schools of social work are growing in scope and number. This article reports on collaboration between a school of social work and a school of engineering, which is forging a new area of interdisciplinary education. The program engages social work students working alongside engineering students in a team approach to…

  20. Effect of interfacial friction during forging of solid powder discs of ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Effect of interfacial friction during forging of solid powder ... deformation. Hence, friction in plastic deformation is essentially different from sliding friction in machine parts. Direct metal-to-metal contact between the die and the ..... Rooks B W 1974 The effect of die temperature on metal flow and die wear during high speed hot.

  1. Influence of forming velocity on the uniformity of microstructure of semisolid die forging 7075 alloy

    Directory of Open Access Journals (Sweden)

    Jianbo TAN

    2016-12-01

    Full Text Available Liquid phase segregation frequently occurs in the process of semi solid die forging, which makes the parts appear "weak point" or "weak region", and usually, the "weak point" or "weak area" is the reason of crack and service condition failure. In order to analyze the influence factors of the liquid phase segregation of the semi solid die forging, DEFORM-3D is used for the numerical simulation of semi-solid die forging forming process of 7075 aluminum alloy, to study the influence rule of forming velocity on the forming process of cup part. Based on the simulation results, the rheological die forging forming of 7075 aluminum alloythe part is conducted to research the influence of forming velocity on the uniformity of microstructure by means of press machine and cup mould. The simulation and experimental results show that as the filling velocity is faster, the forming process is more unstable; under the condition of head temperature of 400 ℃, the forming pressure of 50 MPa, and the alloy temperature 628 ℃, as the forming velocity increases, the liquid phase segregation degree of cup part increases, and the microstructure is far from uniformity. The segregation degree is up to 18.2% as the forming velocity is 5 mm/s.

  2. 76 FR 8773 - Forged Stainless Steel Flanges From India and Taiwan

    Science.gov (United States)

    2011-02-15

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Forged Stainless Steel Flanges From India and Taiwan AGENCY: United States International Trade... steel flanges from India and Taiwan would be likely to lead to continuation or recurrence of material...

  3. 75 FR 67110 - Forged Stainless Steel Flanges From India and Taiwan

    Science.gov (United States)

    2010-11-01

    ... COMMISSION Forged Stainless Steel Flanges From India and Taiwan AGENCY: United States International Trade... stainless steel flanges from India and Taiwan. SUMMARY: The Commission hereby gives notice that it has... Taiwan would be likely to lead to continuation or recurrence of material injury. Pursuant to section 751...

  4. Developments of steel fabrication processes for castings and ingots for forgings

    International Nuclear Information System (INIS)

    Fernandez, S.

    1980-01-01

    This chapter deals with a series of technological developments in the manufacture of steels which have occurred during the last years, in particular reporting the results obtained in Reinosa with some of these methods in the fabrication of castings as well as forgings and rolled products. (author)

  5. Fatigue properties of high-strength materials used in cold-forging tools

    DEFF Research Database (Denmark)

    Brøndsted, P.; Skov-Hansen, P.

    1998-01-01

    In the present work classical analytical models are used to describe the static stress–strain curves, low-cycle fatigue properties and fatigue crack growth behaviour of high-strength materials for use in tools for metal-forming processes such as cold forging and extrusion. The paper describes...

  6. Investigation of the Effect of Forging Temperature on the Microstructure of Grade 5 Titanium ELI

    Directory of Open Access Journals (Sweden)

    Anna Dziubińska

    2017-12-01

    Full Text Available The paper reports the experimental results of an investigation of the effect of forging temperature on the microstructure and hardness of Grade 5 titanium ELI. A growing interest in the use of titanium alloys in implantology results from their unique properties. Grade 5 titanium ELI is widely used in medicine for producing a variety of implants and medical tools such as hip, knee and shoulder joints; bone plates; pacemaker casing and its components; screws; nails; dental materials and tools. In the first part of the paper the properties of Grade 5 titanium ELI are described and examples of medical applications of this alloy are given. In a subsequent section of the paper, forging tests performed on this biomaterial in a temperature range from 750°C to 1100°C are described. Following the forging process, the results of the titanium alloy’s microstructure and hardness are reported. The experimental results are used to determine the most suitable forging temperature range for Grade 5 titanium ELI with respect to its microstructure.

  7. Effect of Forging Allowance Value on the Power Consumption of Machining Process

    Directory of Open Access Journals (Sweden)

    L. D. Mal'kova

    2015-01-01

    Full Text Available The paper aim is to develop and study possible energy-efficiency measures for machined forgings drawing on analysis of the impact of the allowance for machining and its scatter.The most sophisticated option to take into consideration the effect of the cut depth is the work-piece machining in which the forging allowance value results from the blank production.Research of power consumption was conducted for turning the cylindrical surface of 144 mm length and  1,5 33 0,5   diameter on forgings of the work-pieces "screw of steering control" made from steel 60PP. A radial dimension allowance at said cylindrical surface at six points of the five sections was sized to assess the allowance value dispersion. The size of the sample measurements at the control points was n = 600. Statistic processing has shown normal law of distribution and sample homogeneity.To analyze the results of experiments was calculated a range of allowances for this workpiece. Calculated minimum and maximum allowance per one side for rough lathing were, respectively, 0.905 mm and 1.905mm. It was found that 77% points under control lie in calculated range of allowance values. And there are no points out of the range on lesser side that proves a lack of rejects; but there are points out of the range on the bigger side, that will require additional costs for machining the specified surface, including the cost of electricity.There were three power consumption calculations based on factory- recommended duty: for processing the entire sample of forgings with an average allowance, for machining forgings allowances of which are within the recommended design range of allowance, and for processing the entire sample of forgings with a minimum value of allowance.It was found that elimination of allowance values which are outside the recommended range enables to reduce the power consumption, at least, by 6%, and the overall power consumption for processing the measured forgings

  8. Direct metal laser sintering: a digitised metal casting technology.

    Science.gov (United States)

    Venkatesh, K Vijay; Nandini, V Vidyashree

    2013-12-01

    Dental technology is undergoing advancements at a fast pace and technology is being imported from various other fields. One such imported technology is direct metal laser sintering technology for casting metal crowns. This article will discuss the process of laser sintering for making metal crowns and fixed partial dentures with a understanding of their pros and cons.

  9. Monitoring Sintering Burn-Through Point Using Infrared Thermography

    Directory of Open Access Journals (Sweden)

    Francisco G. Bulnes

    2013-08-01

    Full Text Available Sintering is a complex industrial process that applies heat to fine particles of iron ore and other materials to produce sinter, a solidified porous material used in blast furnaces. The sintering process needs to be carefully adjusted, so that the combustion zone reaches the bottom of the material just before the discharge end. This is known as the burnthrough point. Many different parameters need to be finely tuned, including the speed and the quantities of the materials mixed. However, in order to achieve good results, sintering control requires precise feedback to adjust these parameters. This work presents a sensor to monitor the sintering burn-through point based on infrared thermography. The proposed procedure is based on the acquisition of infrared images at the end of the sintering process. At this position, infrared images contain the cross-section temperatures of the mixture. The objective of this work is to process this information to extract relevant features about the sintering process. The proposed procedure is based on four steps: key frame detection, region of interest detection, segmentation and feature extraction. The results indicate that the proposed procedure is very robust and reliable, providing features that can be used effectively to control the sintering process.

  10. Monitoring sintering burn-through point using infrared thermography.

    Science.gov (United States)

    Usamentiaga, Rubén; Molleda, Julio; Garcia, Daniel F; Bulnes, Francisco G

    2013-08-09

    Sintering is a complex industrial process that applies heat to fine particles of iron ore and other materials to produce sinter, a solidified porous material used in blast furnaces. The sintering process needs to be carefully adjusted, so that the combustion zone reaches the bottom of the material just before the discharge end. This is known as the burn-through point. Many different parameters need to be finely tuned, including the speed and the quantities of the materials mixed. However, in order to achieve good results, sintering control requires precise feedback to adjust these parameters. This work presents a sensor to monitor the sintering burn-through point based on infrared thermography. The proposed procedure is based on the acquisition of infrared images at the end of the sintering process. At this position, infrared images contain the cross-section temperatures of the mixture. The objective of this work is to process this information to extract relevant features about the sintering process. The proposed procedure is based on four steps: key frame detection, region of interest detection, segmentation and feature extraction. The results indicate that the proposed procedure is very robust and reliable, providing features that can be used effectively to control the sintering process.

  11. Effects of Sintering Temperature on the Density And Porosity of ...

    African Journals Online (AJOL)

    Effects of sintering temperature on the density and porosity of sodium chloride preforms for alu- minium foam manufacturing have been investigated. Cold pressed salt preforms were sintered at 30, 760 and 790 and di erent times ranging between 6- 18 hours in a carbolite furnace at a heating rate of 5/minute. The Results of ...

  12. Monitoring Sintering Burn-Through Point Using Infrared Thermography

    Science.gov (United States)

    Usamentiaga, Rubén; Molleda, Julio; Garcia, Daniel F.; Bulnes, Francisco G.

    2013-01-01

    Sintering is a complex industrial process that applies heat to fine particles of iron ore and other materials to produce sinter, a solidified porous material used in blast furnaces. The sintering process needs to be carefully adjusted, so that the combustion zone reaches the bottom of the material just before the discharge end. This is known as the burn-through point. Many different parameters need to be finely tuned, including the speed and the quantities of the materials mixed. However, in order to achieve good results, sintering control requires precise feedback to adjust these parameters. This work presents a sensor to monitor the sintering burn-through point based on infrared thermography. The proposed procedure is based on the acquisition of infrared images at the end of the sintering process. At this position, infrared images contain the cross-section temperatures of the mixture. The objective of this work is to process this information to extract relevant features about the sintering process. The proposed procedure is based on four steps: key frame detection, region of interest detection, segmentation and feature extraction. The results indicate that the proposed procedure is very robust and reliable, providing features that can be used effectively to control the sintering process. PMID:23939585

  13. Effect of sintering temperature on structural and electrical properties ...

    Indian Academy of Sciences (India)

    TECS

    vity measurement. The crystallinity and surface morphology of the samples improved with sintering tempera- ture. Further, the electrical conductivity measurement indicated that the conduction mechanism is mainly ionic. The conductivity of samples sintered at 1673 K and 1773 K at 800°C are of the order of 0⋅1 S-cm. –1.

  14. The sintering behavior of close-packed spheres

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Tikare, V.; Frandsen, Henrik Lund

    2012-01-01

    The sintering behavior of close-packed spheres is investigated using a numerical model. The investigated systems are the body-centered cubic (bcc), face-centered cubic (fcc) and hexagonal close-packed spheres (hcp). The sintering behavior is found to be ideal, with no grain growth until full dens...

  15. Field assisted hot pressing of sintering Inconel 718 MIM samples

    Science.gov (United States)

    Dugauguez, Olivier; Torralba, Jose Manuel; Barriere, Thierry; Gelin, Jean-Claude

    2016-10-01

    In this investigation on samples obtained by Metal Injection Molding (MIM), the conventional way of sintering in a furnace will be compared to Field Assisted Hot pressing (FAHP) sintering. The difficulty of this method is to be able to control the shrinkage of the sample and so its shape. It has yet not been investigated with a super alloy powder and so, the effects of a high sintering rate. By accelerating the sintering kinetics, the thermal behavior may be modified. Hence, the behavior of the Inconel 718 sintered by FAHP has been investigated. The sintered samples were all injected from a feedstock composed of a fine particle Inconel powder and a binder principally composed of Cellulose Acetate Butyrate CAB and Poly-Ethylene Glycol PEG. The effects of the two methods on the microstructure and the mechanical properties are then compared. There was no difference in distribution of pores between the conventional sintering and the FAHP sintering but a finer grain size showed better hardness.

  16. Sintering of Multilayered Porous Structures: Part I-Constitutive Models

    DEFF Research Database (Denmark)

    Olevsky, Eugene; Tadesse Molla, Tesfaye; Frandsen, Henrik Lund

    2013-01-01

    Theoretical analyses of shrinkage and distortion kinetics during sintering of bilayered porous structures are carried out. The developed modeling framework is based on the continuum theory of sintering; it enables the direct assessment of the cofiring process outcomes and of the impact of process...

  17. Microstructure and properties of sintered mullite developed from ...

    Indian Academy of Sciences (India)

    Dense mullite aggregates with 72% Al2O3 have been synthesized by reaction sintering of two varieties of Indian bauxite and silica sol. The bauxites used are of inferior grade with different levels of accessory impurities such as Fe2O3, TiO2, CaO. The phase and microstructure development of sintered samples were ...

  18. Sintering, camber development of layer composites and a new ...

    Indian Academy of Sciences (India)

    NiZnCu hexagonal ferrite (abbreviated as ZT/NZC) composite samples were prepared successfully by using restricted shrinkage sintering process (RSS) (Liu et al 2009a, b). But the electromagnetic performance degra- dation of co-sintered layer ...

  19. Corrosion behaviour of sintered duplex stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Utrilla, M. Victoria; Urena, Alejandro; Otero, Enrique; Munez, Claudio Jose [Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, C/ Tulipan s/n, 28933 Mostoles, Madrid (Spain)

    2004-07-01

    Duplex austenite-ferrite stainless steels were prepared by mixing austenitic (316L) and ferritic (434L) atomized powders. Although different 316L/434L ratios were prepared, present work centred its study on 50% ferrite - 50% austenite sintered steel. The powders were mixed and pressed at 700 MPa and sintered at 1250 deg. C for 30 min in vacuum. The cooling rate was 5 deg. C/min. Solution treatment was carried out to homogenize the microstructure at 1100 deg. C during 20 min. A microstructural study of the material in solution was performed, evaluating the microstructure, proportion and shape of porosity, and ferrite percentage. This last was measured by two methods, quantitative metallography and Fischer ferrito-metry. The materials were heat treated in the range of 700 to 1000 deg. C, for 10, 30 and 60 min and water quenched, to study the microstructural changes and the influence on the intergranular corrosion resistance. The method used to evaluate the sensitization to the intergranular corrosion was the electrochemical potentio-kinetic reactivation procedure (EPR). The test solution was 0.5 M H{sub 2}SO{sub 4} + 0,01 M KSCN at 30 deg. C. The criterion used to evaluate the sensitization was the ratio between the maximum reactivation density (Ir) and the maximum activation density (Ia). The results of the electrochemical tests were discussed in relation with the microstructures observed at the different heat treatments. (authors)

  20. The Emergence of Quantitative Sintering Theory from 1945 to 1955

    Science.gov (United States)

    German, Randall M.

    2017-04-01

    Particles flow and pack under stress, allowing shaping of the particles into target engineering geometries. Subsequently, in a process termed sintering, the particles are heated to induce bonding that results in a strong solid. Although first practiced 26,000 years ago, sintering was largely unexplained until recent times. Sintering science moved from an empirical and largely qualitative notion into a quantitative theory over a relatively short time period following World War II. That conceptual transition took place just as commercial applications for sintered materials underwent significant growth. This article highlights the key changes in sintering concepts that occurred in the 1945-1955 time period. This time span starts with the first quantitative neck growth model from Frenkel and ends with the quantitative shrinkage model from Kingery and Berg that includes several transport mechanisms.

  1. Preliminary investigation of liquid phase sintering in ferrous systems

    International Nuclear Information System (INIS)

    Klein, J.

    1975-04-01

    Liquid phase sintering was utilized to achieve, by a simple compaction and sintering procedure involving short times and moderate temperatures, a virtually full dense high carbon Fe:C alloy and high boron Fe:B alloy. Parameters such as powder characteristics and mixing, compacting pressure, heating program and the liquid phase fraction were found to influence the sintered density. The response of the Fe:C alloy to a heat treatment is reported along with preliminary experiments in the iron base ternary system Fe:W:C. Residual porosities observed in microstructures of certain liquid phase sintered compacts were accounted for by a proposed capillary flow of the liquid phase and a local densification competing against an overall densification. Some general recommendations are made for liquid phase sintering of powder aggregates. 15 fig., 7 tables

  2. Sintering with a chemical reaction as applied to uranium monocarbide

    International Nuclear Information System (INIS)

    Accary, A.; Caillat, R.

    1960-01-01

    The present paper provides a survey of different investigations whose aim was the preparation and fabrication of uranium monocarbide for nuclear use. If a chemical reaction takes place in the sample during the sintering operation, it may be expected that the atom rearrangements involved in this reaction should favour the sintering process and thereby lower the temperature needed to yield a body of a given density. With this hypothesis in mind, the following methods have been studied: - Sintering of U-C mixtures; - Sintering of UO 2 -C mixtures; - Hot pressing of U-C mixtures; - Extrusion of U-C mixtures. To generalize our result, it could be said that a chemical reaction does not lead to high densification, if one depends on a simple contact between discrete particles. On the contrary, a chemical reaction can help sintering if, as our hot pressing experiments shows, the densification can be achieved prior to the reaction. (author) [fr

  3. Sintered silver joints via controlled topography of electronic packaging subcomponents

    Science.gov (United States)

    Wereszczak, Andrew A.

    2014-09-02

    Disclosed are sintered silver bonded electronic package subcomponents and methods for making the same. Embodiments of the sintered silver bonded EPSs include topography modification of one or more metal surfaces of semiconductor devices bonded together by the sintered silver joint. The sintered silver bonded EPSs include a first semiconductor device having a first metal surface, the first metal surface having a modified topography that has been chemically etched, grit blasted, uniaxial ground and/or grid sliced connected to a second semiconductor device which may also include a first metal surface with a modified topography, a silver plating layer on the first metal surface of the first semiconductor device and a silver plating layer on the first metal surface of the second semiconductor device and a sintered silver joint between the silver plating layers of the first and second semiconductor devices which bonds the first semiconductor device to the second semiconductor device.

  4. Intense pulsed light sintering of copper nanoink for printed electronics

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hak-Sung; Dhage, Sanjay R.; Shim, Dong-Eun [University of California, Mechanical and Aerospace Engineering Department, Los Angeles, CA (United States); Hahn, H.T. [University of California, Mechanical and Aerospace Engineering Department, Los Angeles, CA (United States); University of California, Material Science and Engineering Department, California NanoSystems Institute, Los Angeles, CA (United States)

    2009-12-15

    An intense pulsed light (IPL) from a xenon flash lamp was used to sinter copper nanoink printed on low-temperature polymer substrates at room temperature in ambient condition. The IPL can sinter the copper nanoink without damaging the polymer substrates in extremely short time (2 ms). The microstructure of the sintered copper film was investigated using X-ray powder diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), X-ray micro tomography, and atomic force microscopy (AFM). The sintered copper film has a grainy structure with neck-like junctions. The resulting resistivity was 5{mu}{omega} cm of electrical resistivity which is only 3 times as high as that of bulk copper. The IPL sintering technique allows copper nanoparticles to be used in inkjet printing on low-temperature substrates such as polymers in ambient conditions. (orig.)

  5. Microstructure evolution during pressureless sintering of bulk oxide ceramics

    Directory of Open Access Journals (Sweden)

    Karel Maca

    2009-06-01

    Full Text Available The author’s experience concerning the infl uence of the choice of different pressureless heating schedules on the fi nal microstructure of oxide ceramic materials is summarized in the paper. Alumina, ceria, strontium titanate, as well as tetragonal (3 mol% Y2O3 and cubic (8 mol% Y2O3 zirconia were cold isostatically pressed or injection moulded and pressureless sintered with different heating schedules – namely with Constant-Rate of Heating with different dwell temperatures (CRH, with Rate-Controlled Sintering (RCS and with Two-Step Sintering (TSS. It was examined whether some of these three sintering schedules, with the same fi nal density achieved, can lead to a decrease of the grain size of sintered ceramics. The results showed that only TSS (and only for selected materials brought significant decrease of the grain size.

  6. Ash chemistry and sintering, verification of the mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Hupa, M.; Skrifvars, B.J.; Backman, R.; Lauren, T.; Uusikartano, T.; Malm, H.; Stenstroem, P.; Vesterkvist, M. [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group

    1997-10-01

    In this project four sintering mechanisms have been studied, i.e., partial melting with a viscous liquid, partial melting with a non-viscous liquid, chemical reaction sintering and solid state sintering. The work has aimed at improving the understanding of ash sintering mechanisms and quantifying their role in combustion and gasification. The work has been oriented in particular on the understanding of biomass ash behavior. The work has not directly focused on any specific technical application. However, results can also be applied on other fuels such as brown coal, petroleum coke, black liquor and different types of wastes (PDF, RDF, MSW). During 1996 the work has focused on identifying bed agglomeration mechanisms and analysing bed agglomerates in both full scale and lab scale FB reactors, as well as comparing how well the compression strength based sintering test can predict bed agglomeration in an FB furnace. (orig.)

  7. Study on selective laser sintering of glass fiber reinforced polystyrene

    Science.gov (United States)

    Yang, Laixia; Wang, Bo; Zhou, Wenming

    2017-12-01

    In order to improve the bending strength of Polystyrene (PS) sintered parts by selective laser sintering, Polystyrene/glass fiber (PS/GF) composite powders were prepared by mechanical mixing method. The size distribution of PS/GF composite powders was characterized by laser particle size analyzer. The optimum ratio of GF was determined by proportioning sintering experiments. The influence of process parameters on the bending strength of PS and PS/GF sintered parts was studied by orthogonal test. The result indicates that the particle size of PS/GF composite powder is mainly distributed in 24.88 μm~139.8 μm. When the content of GF is 10%, it has better strengthen effect. Finally, the article used the optimum parameter of the two materials to sinter prototype, it is found that the PS/GF prototype has the advantages of good accuracy and high strength.

  8. Powder metallurgy: Solid and liquid phase sintering of copper

    Science.gov (United States)

    Sheldon, Rex; Weiser, Martin W.

    1993-01-01

    Basic powder metallurgy (P/M) principles and techniques are presented in this laboratory experiment. A copper based system is used since it is relatively easy to work with and is commercially important. In addition to standard solid state sintering, small quantities of low melting metals such as tin, zinc, lead, and aluminum can be added to demonstrate liquid phase sintering and alloy formation. The Taguchi Method of experimental design was used to study the effect of particle size, pressing force, sintering temperature, and sintering time. These parameters can be easily changed to incorporate liquid phase sintering effects and some guidelines for such substitutions are presented. The experiment is typically carried out over a period of three weeks.

  9. Three-dimensional simulation of viscous-flow agglomerate sintering.

    Science.gov (United States)

    Kirchhof, M J; Schmid, H -J; Peukert, W

    2009-08-01

    The viscous-flow sintering of different agglomerate particle morphologies is studied by three-dimensional computer simulations based on the concept of fractional volume of fluid. For a fundamental understanding of particle sintering characteristics, the neck growth kinetics in agglomerate chains and in doublets consisting of differently sized primary particles is investigated. Results show that different sintering contacts in agglomerates even during the first stages are not completely independent from each other, even though differences are small. The neck growth kinetics of differently sized primary particles is determined by the smaller one up to a size difference by a factor of approximately 2, whereas for larger size differences, the kinetics becomes faster. In particular, the agglomerate sintering kinetics is investigated for particle chains of different lengths and for different particle morphologies each having ten primary particles and nine initial sintering contacts. For agglomerate chains, the kinetics approximately can be normalized by using the radius of the fully coalesced sphere. In general, different agglomerate morphologies show equal kinetics during the first sintering stages, whereas during advanced stages, compact morphologies show significantly faster sintering progress than more open morphologies. Hence, the overall kinetics cannot be described by simply using constant morphology correction factors such as fractal dimension or mean coordination number which are used in common sintering models. However, for the first stages of viscous-flow agglomerate sintering, which are the most important for many particle processes, a sintering equation is presented. Although we use agglomerates consisting of spherical primary particles, our methodology can be applied to other aggregate geometries as well.

  10. Development of production technology and investigation of quality for forged-welded turbine rotors of steel 25Kh2NVFA

    International Nuclear Information System (INIS)

    Borisov, I.A.; Merinov, G.N.; Slezkina, E.V.

    1997-01-01

    A study was made into mechanical properties and microstructure of turbine rotor components manufactured by forging and heat treated under various conditions. It is revealed that the optimal heat treatment of forgings must include double quenching with subsequent tempering at 630-640 deg C for 10-20 h. Forged and welded rotors should be tempered at 620-630 deg C for 50-100 h. Microscopic examination and mechanical tests showed that low alloy steel 25Kh2NMF can be successfully used for manufacturing rotors of high-, medium-and low-heat turbines

  11. Rietveld texture analysis of complex oxides: examples of polyphased Bi2223 superconducting and Co349 thermoelectric textured ceramics characterization using neutron and X-ray diffraction

    International Nuclear Information System (INIS)

    Guilmeau, E.; Chateigner, D.; Noudem, J.; Funahashi, R.; Horii, S.

    2005-01-01

    Orientation distributions of cobaltite thermoelectric and polyphased bismuth-based cuprate superconducting textured materials are determined from neutron and X-ray diffraction analysis. Curved position-sensitive detectors coupled to a tilt-angle (χ) scan enable the treatment of the whole diffraction pattern using the combined Rietveld-WIMV-Popa algorithm. The textures of three phases of superconducting compounds are determined. The critical current densities, measured for four samples, are strongly dependent on the calculated texture strengths, crystallite sizes and phase ratios. For the cobaltite compounds, a comparison between X-ray and neutron analysis shows the advantages of the latter technique for avoiding the limitations of the X-ray analysis with respect to the defocusing effect. The results highlight the necessity and efficiency of the combined approach for a quantitative texture analysis of complex materials and exemplify the texture-anisotropic physical properties relationship for a better understanding and design of improved bulk superconducting and thermoelectric materials

  12. Analysis of quench development in a cryocooler cooled Bi-2223 pancake coil based on the anisotropic transport E-J characteristics in a short tape sample

    NARCIS (Netherlands)

    Kiss, T.; Noda, S.; Nishimura, S.; Ohya, K.; Utsunomiya, D.; Ilyin, Y.; Okamoto, H.

    2001-01-01

    By calculating the magnetic field distribution in a stacked pancake coil with use of finite element method and by taking into account the transport properties obtained in a short tape sample, we predict the electric field vs. current density, E–J, characteristics depending on the position inside the

  13. Sintered soft magnetic materials. Properties and applications

    Science.gov (United States)

    Bas, J. A.; Calero, J. A.; Dougan, M. J.

    2003-01-01

    A comparison is presented of the characteristics and production requirements of a variety of materials used to produce sintered soft magnetic parts. These include pure iron, phosphorous-iron, silicon-iron, nickel-iron, and cobalt-iron, together with new coated materials based on encapsulated iron powders. In these bonded materials an organic and/or inorganic insulator is used to coat the metallic powder particles giving a magnetic composite. The suitability of the different materials for use in both direct and alternating current applications is reviewed, and examples are provided of their application in both the automotive and other sectors. The results of a comparative study of motors using stators and rotors based on both conventional laminated materials and the insulated iron powders are presented, in which the new materials show advantages of reduced hysteresis losses at high frequencies, and isotropy of magnetic properties. Nevertheless, the applications of these materials in electrical motors requires the modification of existing designs.

  14. Sintering and microstructure evolution in columnar thermal barrier coatings

    International Nuclear Information System (INIS)

    Krishnamurthy, Ramanathan; Srolovitz, David J.

    2009-01-01

    Sintering of thermal barrier coatings changes their key properties, such as thermal conductivity and thermal shock resistance, thus adversely impacting their reliability. We present a novel modeling approach to study the evolution of coating structure during sintering. We model the sintering of individual columns using a thermodynamic principle, and incorporate the center-to-center approach rates for the columns calculated using this principle in a larger scale discrete dynamics model for the evolution of a large number of columns. Surface energies, grain boundary energies and strain energies associated with the deformation of the columns are all included in this framework, while sintering is assumed to occur by the concerted action of surface and grain boundary diffusion. Two sets of initial conditions corresponding to different extents of pre-sintering among neighboring columns are considered. When the extent of pre-sintering is small, we observe that small clusters containing 5-20 columns are formed. In contrast, where a larger amount of pre-sintering exists, we observe, especially at large column densities, that clusters containing 50-100 columns separated by large inter-cluster pores/channels that appear to organize themselves into a network are formed. These observations are in good agreement with recently published experimental observations. We also explain how these results can explain the development of a 'mud-crack'-like pattern

  15. Embrittling Components in Sintered Steels: Comparison of Phosphorus and Boron

    Science.gov (United States)

    Danninger, Herbert; Vassileva, Vassilka; Gierl-Mayer, Christian

    2017-12-01

    In ferrous powder metallurgy, both boron and phosphorus have been known to be sintering activators for a long time. However, the use has been widely different: while P is a standard additive to sintered iron and steels, boron has been frequently studied, but its use in practice is very limited. Both additives are also known to be potentially embrittling, though in a different way. In the present study the differences between the effects of both elements are shown: while P activates sintering up to a certain threshold, in part by stabilizing ferrite, in part by forming a transient liquid phase, boron is the classical additive enhancing persistent liquid phase, being virtually insoluble in the iron matrix. The consequence is that sintered steels can tolerate quite a proportion of phosphorus, depending on composition and sintering process; boron however is strongly embrittling in particular in combination with carbon, which requires establishing a precisely defined content that enhances sintering but is not yet embrittling. The fracture mode of embrittled materials is also different: while with Fe-P the classical intergranular fracture is observed, with boron a much more rugged fracture surface appears, indicating some failure through the eutectic interparticle network but mostly transgranular cleavage. If carbon is added, in both cases transgranular cleavage dominates even in the severely embrittled specimens, indicating that no more the grain boundaries and sintering necks are the weakest links in the systems.

  16. Forming of Hollow Shaft Forging From Titanium Alloy Ti6Al4V by Means of Rotary Compression

    Directory of Open Access Journals (Sweden)

    Tomczak J.

    2015-04-01

    Full Text Available This paper presents chosen results of theoretical-experimental works concerning forming of hollow shafts forgings from titanium alloys, which are applied in aviation industry. At the first stage of conducted analysis, the forging forming process was modeled by means of finite element method. Calculations were made using software Simufact Forming. On the basis of performed simulations optimal parameters of rotary compression process were determined. Next, experimental tests of forging forming in laboratory conditions were made. For the research needs, a forging aggregate, designed by the Authors, was used. Conducted research works confirmed the possibility of metal forming (by means of rotary compression of hollow shafts from hard workable titanium alloys. Numerous advantages of rotary compression process, make it attractive both for low series production (aircraft industry and for mass production (automotive industry.

  17. 76 FR 24856 - Heavy Forged Hand Tools (i.e., Axes & Adzes, Bars & Wedges, Hammers & Sledges, and Picks...

    Science.gov (United States)

    2011-05-03

    ... also Antidumping Duty Orders: Heavy Forged Hand Tools, Finished or Unfinished, With or Without Handles... the Orders. \\1\\ Ames is the successor company to Woodings-Verona Tools Works, the petitioner in the...

  18. Numerical simulation and experimental verification of microstructure evolution in large forged pipe used for AP1000 nuclear power plants

    International Nuclear Information System (INIS)

    Wang, Shenglong; Yang, Bin; Zhang, Mingxian; Wu, Huanchun; Peng, Jintao; Gao, Yang

    2016-01-01

    Highlights: • Establish systematically the database of 316LN stainless steel for Deform-3D. • Simulate the microstructure evolution during forging of AP1000 primary coolant pipe. • Carry out full-scale forging experiment for verification in engineering practice. • Get desirable grain size in simulation and experiment. • The variation trends of grain sizes in simulation and experiment are consistent. - Abstract: AP1000 primary coolant pipe is a large special-shaped forged pipe made of 316LN stainless steel. Due to the non-uniform temperature and deformation during its forging, coarse and fine grains usually coexist in the forged pipe, resulting in the heterogeneous microstructure and anisotropic performance. To investigate the microstructure evolution during the entire forging process, in the present research, the database of the 316LN stainless steel was established and a numerical simulation was performed. The results indicate that the middle body section of the forged pipe has an extremely uniform average grain size with the value smaller than 30 μm. The grain sizes in the ends of body sections were ranged from 30 μm to 60 μm. Boss sections have relatively homogeneous microstructure with the average grain size 30 μm to 44 μm. Furthermore, a full-scale hot forging was carried out for verification. Comparison of theoretical and experimental results showed good agreement and hence demonstrated the capabilities of the numerical simulation presented here. It is noteworthy that all grains in the workpiece were confirmed less than 180 μm, which meets the designer’s demands.

  19. Effects of various additives on sintering of aluminum nitride

    Science.gov (United States)

    Komeya, K.; Inoue, H.; Tsuge, A.

    1982-01-01

    Effects of thirty additives on sintering A/N were investigated. The addition of alkali earth oxides and rare earth oxides gave fully densified aluminum nitride. This is due to the formation of nitrogen-containing aluminate liquid in the system aluminum nitride-alkali earth oxides or rare earth oxides. Microstructural studies of the sintered specimens with the above two types of additives suggested that the densification was due to the liquid phase sintering. Additions of silicon compounds resulted in poor densification by the formation of highly refractory compounds such as A/N polytypes.

  20. Low temperature spark plasma sintering of YIG powders

    International Nuclear Information System (INIS)

    Fernandez-Garcia, L.; Suarez, M.; Menendez, J.L.

    2010-01-01

    A transition from a low to a high spin state in the magnetization saturation between 1000 and 1100 o C calcination temperature is observed in YIG powders prepared by oxides mixture. Spark plasma sintering of these powders between 900 and 950 o C leads to dense samples with minimal formation of YFeO 3 , opening the way to co-sintering of YIG with metals or metallic alloys. The optical properties depend on the sintering stage: low (high) density samples show poor (bulk) optical absorption.

  1. Phenomenological theory of sintering and its application to swelling

    Directory of Open Access Journals (Sweden)

    Kornyushin Y.

    2004-01-01

    Full Text Available The general phenomenological theory of sintering, formulated by the author in 1998 is applied to the problem of swelling. Driving forces, caused by the presence of the evolution of heat in the volume of a sample (electric contact, hf, inductive heating or penetrating radiation, e.g., neutrons could be the sources of the heat in the bulk of a sample are considered. The influence of these driving forces on sintering, structure and properties is discussed. The role of mobile and immobile dislocations, grain boundaries, and pores is considered. Cycling and pulsing regimes of sintering are investigated.

  2. Microwave sintering of nanophase ceramics without concomitant grain growth

    Science.gov (United States)

    Eastman, Jeffrey A.; Sickafus, Kurt E.; Katz, Joel D.

    1993-01-01

    A method of sintering nanocrystalline material is disclosed wherein the nanocrystalline material is microwaved to heat the material to a temperature less than about 70% of the melting point of the nanocrystalline material expressed in degrees K. This method produces sintered nanocrystalline material having a density greater than about 95% of theoretical and an average grain size not more than about 3 times the average grain size of the nanocrystalline material before sintering. Rutile TiO.sub.2 as well as various other ceramics have been prepared. Grain growth of as little as 1.67 times has resulted with densities of about 90% of theoretical.

  3. Manufacturing of metal supported BSCF membranes by spark plasma sintering

    OpenAIRE

    Laptev, Alexander; Bram, Martin; Zivcec, Maria; Baumann, Stefan; Jarligo, Maria Ophelia; Sebold, Doris; Pfaff, Ewald; Broeckmann, Christoph

    2013-01-01

    Spark plasma sintering (SPS), also known as field assisted sintering technique (FAST), is a relatively new method for rapid consolidation of metallic or ceramic powders. In the present work, its suitability for the manufacturing of metal supported Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) based membrane by co-sintering of functional ceramic BSCF layer and porous metallic support has been investigated. The BSCF based membranes are highly attractive for oxygen separation from air due to mixed ionic and e...

  4. Cleanable sintered metal filters in hot off-gas systems

    International Nuclear Information System (INIS)

    Schurr, G.A.

    1981-01-01

    Filters with sintered metal elements, arranged as tube bundles with backflush air cleaning, are the equivalent of bag filters for high-temperature, harsh environments. They are virtually the only alternative for high-temperature off-gas systems where a renewable, highly efficient particle trap is required. Tests were conducted which show that the sintered metal elements installed in a filter system provide effective powder collection in high-temperature atmospheres over thousands of cleaning cycles. Such a sintered metal filter system is now installed on the experimental defense waste calciner at the Savannah River Laboratory. The experimental results included in this paper were used as the basis for its design

  5. Low temperature spark plasma sintering of YIG powders

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Garcia, L. [Department of Nanostructured Materials, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN). Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Suarez, M., E-mail: m.suarez@cinn.e [Department of Nanostructured Materials, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN). Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Fundacion ITMA, Parque Tecnologico de Asturias, 33428, Llanera (Spain); Menendez, J.L. [Department of Nanostructured Materials, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN). Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain)

    2010-07-16

    A transition from a low to a high spin state in the magnetization saturation between 1000 and 1100 {sup o}C calcination temperature is observed in YIG powders prepared by oxides mixture. Spark plasma sintering of these powders between 900 and 950 {sup o}C leads to dense samples with minimal formation of YFeO{sub 3}, opening the way to co-sintering of YIG with metals or metallic alloys. The optical properties depend on the sintering stage: low (high) density samples show poor (bulk) optical absorption.

  6. HYDROGEN EFFECTS ON THE FRACTURE TOUGHNESS PROPERTIES OF FORGED STAINLESS STEELS

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, M

    2008-03-28

    The effect of hydrogen on the fracture toughness properties of Types 304L, 316L and 21-6-9 forged stainless steels was investigated. Fracture toughness samples were fabricated from forward-extruded forgings. Samples were uniformly saturated with hydrogen after exposure to hydrogen gas at 34 MPa or 69 and 623 K prior to testing. The fracture toughness properties were characterized by measuring the J-R behavior at ambient temperature in air. The results show that the hydrogen-charged steels have fracture toughness values that were about 50-60% of the values measured for the unexposed steels. The reduction in fracture toughness was accompanied by a change in fracture appearance. Both uncharged and hydrogen-charged samples failed by microvoid nucleation and coalescence, but the fracture surfaces of the hydrogen-charged steels had smaller microvoids. Type 316L stainless steel had the highest fracture toughness properties and the greatest resistance to hydrogen degradation.

  7. Qualification of laser based additive production for manufacturing of forging Tools

    Directory of Open Access Journals (Sweden)

    Junker Daniel

    2015-01-01

    Full Text Available Mass customization leads to very short product life cycles, so the costs of a tool have to be amortized with a low number of workpieces. Especially for highly loaded tools, like those for forging, that leads to expensive products. Therefore more economical production processes for tool manufacturing have to be investigated. As laser additive manufacturing is already used for the production of moulds for injection moulding, this technology maybe could also improve the forging tool production. Within this paper laser metal deposition, which is industrially used for tool repair, will be investigated for the use in tool manufacturing. Therefore a mechanical characterization of parts built with different laser process parameters out of the hot work tool steel 1.2709 is made by upsetting tests and hardness measurements. So the influence of the additive manufacturing process on the hardness distribution is analysed.

  8. Effects of Austenitizing and Forging on Mechanical Properties of MIL A-12560/AISI 4340 Steel

    Science.gov (United States)

    Herbirowo, S.; Adjiantoro, B.; Romijarso, T. B.

    2017-05-01

    Laterite steels might be used for alternative armored steels. Their properties can be improved in various ways, such as by heat treatment. This paper reports the influences of tempering temperature on the hardness and microstructure of the modified MIL A-12560/AISI 4340 steels. Samples were austenitized at 1200, 1000, and 800°C and forged at 100, 75, and 50 tons. Mechanical properties consisted of Hardness measurement was conducted by Brinell indentation and metallographic observation was conducted by scanning electron microscopy (SEM). The results showed that increasing forging force until 100 tons can decrease hardness. The formation of the microstructure consists of tempered martensite containing ferrite and dual phase perlite. The presence of void and porous can also decrease hardness. Decreasing austenizing temperature from 1200 °C to 800°C can increase material strength and hardness.

  9. Thixo forging process of wrought aluminum alloy fabricated by rotational helical shape stirrer

    International Nuclear Information System (INIS)

    Lee, S. M.; Han, S. H.; Kang, C. G.

    2007-01-01

    The manufacture of rheology materials from wrought and casting aluminum alloys using controlling solid fraction and crystal grain is demonstrated in this paper. The equipment to form the rheology material was designed so that shear force and applied pressure could be carefully and simultaneously applied using a mechanical stirrer. The problems caused by using this method with the thixo forging process were studied by investigating the mechanical properties of a sample that had a controlled solid fraction of 45-50 %

  10. HaploForge: a comprehensive pedigree drawing and haplotype visualization web application.

    Science.gov (United States)

    Tekman, Mehmet; Medlar, Alan; Mozere, Monika; Kleta, Robert; Stanescu, Horia

    2017-12-15

    Haplotype reconstruction is an important tool for understanding the aetiology of human disease. Haplotyping infers the most likely phase of observed genotypes conditional on constraints imposed by the genotypes of other pedigree members. The results of haplotype reconstruction, when visualized appropriately, show which alleles are identical by descent despite the presence of untyped individuals. When used in concert with linkage analysis, haplotyping can help delineate a locus of interest and provide a succinct explanation for the transmission of the trait locus. Unfortunately, the design choices made by existing haplotype visualization programs do not scale to large numbers of markers. Indeed, following haplotypes from generation to generation requires excessive scrolling back and forth. In addition, the most widely used program for haplotype visualization produces inconsistent recombination artefacts for the X chromosome. To resolve these issues, we developed HaploForge, a novel web application for haplotype visualization and pedigree drawing. HaploForge takes advantage of HTML5 to be fast, portable and avoid the need for local installation. It can accurately visualize autosomal and X-linked haplotypes from both outbred and consanguineous pedigrees. Haplotypes are coloured based on identity by descent using a novel A* search algorithm and we provide a flexible viewing mode to aid visual inspection. HaploForge can currently process haplotype reconstruction output from Allegro, GeneHunter, Merlin and Simwalk. HaploForge is licensed under GPLv3 and is hosted and maintained via GitHub. https://github.com/mtekman/haploforge. r.kleta@ucl.ac.uk. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  11. Analog Audio Format Changes From Being Digital Audio Using Sony Sound Forge 9.0

    OpenAIRE

    Faisal Safrudin; Yulina Yulina

    2010-01-01

    Perubahan sebuah audio analog ke audio digital tidak hanya berguna padakalangan jurnalis atau wartawan juga bermanfaat untuk khalayak umumsekalipun. Pada teknologi sebelumnya banyak kita jumpai hampir setiap orangmenggunakan audio analog yaitu berupa kaset. Sejalannya perkembanganteknologi, format audio analog sudah jarang digunakan dengan hadirnya audiodigital, namun hal tersebut dapat diatasi dengan merubah format audio analog keaudio digital dengan menggunakan Sony Sound Forge 9.0. Penulis...

  12. WordForge | CRDI - Centre de recherches pour le développement ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Cette subvention permet à Zuza Software Foundation, Afrique du Sud, de développer un outil informatique (WordForge) qui permet de gérer de façon méthodologique transparente le processus de localisation ... Le CRDI offre un appui essentiel à la recherche en santé mondiale au Moyen-Orient et en Afrique du Nord.

  13. Tunneling corrosion mechanism of the hot forged austenitic stainless steel in highly oxidizing nitric acid

    International Nuclear Information System (INIS)

    Nagano, Hiroo; Kajimura, Haruhiko

    1993-01-01

    Austenitic Stainless Steels have been used for reprocessing plants where spent nuclear fuels are dealt with in hot nitric acid. Conventional stainless steels are resistant enough to nitric acid. However, they are prone to localized corrosion when nitric acid becomes highly oxidizing with birth of oxidants such as Ce 4+ or Cr 6+ ion during the reprocessing. Pitting type corrosion, so-called tunneling or end-grain corrosion occurred on the forgings of 25%-20%-Nb stainless steel (310Nb stainless steel) in such nitric acid solutions because of transpassive corrosion. It has been well known that metal surfaces of steel products casted, forged or rolled are susceptible to the tunneling corrosion in aggressive corrosion media. Nevertheless, neither clear explanations of the mechanism nor definite countermeasures have been proposed yet. This paper describes the mechanism and countermeasures on the tunneling corrosion of stainless steels in nitric acid relevant to spent nuclear fuel reprocessing. The results obtained are as follows: both general and intergranular corrosion occur on austenitic stainless steels in boiling 8N HNO 3 with Cr 6+ ions. Tunneling corrosion is initiated and propagates at the metal surfaces of 310Nb stainless steel forgings along chromium depleted areas vertical to metal flows. The grooves due to the tunneling corrosion are of diameters of 0.5 to 2 mm with a maximum depth of 6mm depending on exposure time and Cr 6+ concentration in nitric acid. Tunneling corrosion proceeds by build up of galvanic corrosion cells with Cr depleted parts as anodes and their neighborhoods as cathodes. The Cr depleted parts are formed during solidification of ingots and still retained parallel to the metal flow even after forging. The ESR (Electro Slag Remelting) is one of the useful preventive methods to tunneling corrosion from the view point of steel homogenization

  14. University hosts symposium to forge agenda for financial regulatory reform; transparency cited as major challenge

    OpenAIRE

    Micale, Barbara L.

    2009-01-01

    Virginia Tech National Capital Region recently hosted a symposium titled "A Public Administration Moment: Forging an Agenda for Financial Regulatory Reform" to address such relevant topics as: How can financial regulation be made more transparent? What is the government's role in regulating financial innovation and risk? What are the educational challenges in preparing public administrators for financial regulation? And what are the lessons from rapid responses to tough economic issues?

  15. Effect of forging strain rate and deformation temperature on the mechanical properties of warm-worked 304L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Switzner, N. T. [Honeywell Federal Manufacturing & Technologies, Kansas City, MO (United States); Van Tyne, C. J. [Colorado School of Mines, Golden, CO (United States). Dept. of Metallurgical and Materials Engineering; Mataya, M. C. [Colorado School of Mines, Golden, CO (United States). Dept. of Metallurgical and Materials Engineering

    2010-01-25

    Stainless steel 304L forgings were produced with four different types of production forging equipment – hydraulic press, mechanical press, screw press, and high-energy rate forging (HERF). Each machine imparted a different nominal strain rate during the deformation. The final forgings were done at the warm working (low hot working) temperatures of 816 °C, 843°C, and 871°C. The objectives of the study were to characterize and understand the effect of industrial strain rates (i.e. processing equipment), and deformation temperature on the mechanical properties for the final component. Some of the components were produced with an anneal prior to the final forging while others were deformed without the anneal. The results indicate that lower strain rates produced lower strength and higher ductility components, but the lower strain rate processes were more sensitive to deformation temperature variation and resulted in more within-part property variation. The highest strain rate process, HERF, resulted in slightly lower yield strength due to internal heating. Lower processing temperatures increased strength, decreased ductility but decreased within-part property variation. The anneal prior to the final forging produced a decrease in strength, a small increase in ductility, and a small decrease of within-part property variation.

  16. Porosity, Microstructure, and Mechanical Properties of Ti-6Al-4V Alloy Parts Fabricated by Powder Compact Forging

    Science.gov (United States)

    Jia, Mingtu; Zhang, Deliang; Liang, Jiamiao; Gabbitas, Brian

    2017-04-01

    Ti-6Al-4V alloy powders produced using a hydrogenation-dehydrogenation process and a gas atomization process, respectively, were rapidly consolidated into near-net-shaped parts by powder compact forging. The porosity, microstructure, and tensile mechanical properties of specimens cut from regions at different distances from the side surfaces of the forged parts were examined. The regions near the side surfaces contained a fraction of pores due to the circumferential tensile strain arising during the powder compact forging process, and the porosity level decreased rapidly to zero with increasing the distance from the side surface. The forged parts had a fully lamellar structure with the α + β colony sizes and α lamella thickness changing little with the distance from the side surface. The specimens cut from the regions near the side surfaces had a lower yield strength and tensile strength. The correlation of porosity with the yield strength of the specimens suggested that the reduction of load bearing areas due to the porosity and unbonded or weakly bonded interparticle boundaries was not the only reason for the lower strength, and the stress concentration at the pores and associated with their geometry also played an important role in this. It is likely that the effect of stress concentration on yield strength reduction of the forged part increases with oxygen content. The Hall-Petch relationship of the yield strength and the average α lamella thickness suggested that the strength of the fully dense and fully consolidated forged parts was increased by oxygen solution strengthening.

  17. Sintering equation: determination of its coefficients by experiments - using multiple regression

    International Nuclear Information System (INIS)

    Windelberg, D.

    1999-01-01

    Sintering is a method for volume-compression (or volume-contraction) of powdered or grained material applying high temperature (less than the melting point of the material). Maekipirtti tried to find an equation which describes the process of sintering by its main parameters sintering time, sintering temperature and volume contracting. Such equation is called a sintering equation. It also contains some coefficients which characterise the behaviour of the material during the process of sintering. These coefficients have to be determined by experiments. Here we show that some linear regressions will produce wrong coefficients, but multiple regression results in an useful sintering equation. (orig.)

  18. Intersubjective decision-making for computer-aided forging technology design

    Science.gov (United States)

    Kanyukov, S. I.; Konovalov, A. V.; Muizemnek, O. Yu.

    2017-12-01

    We propose a concept of intersubjective decision-making for problems of open-die forging technology design. The intersubjective decisions are chosen from a set of feasible decisions using the fundamentals of the decision-making theory in fuzzy environment according to the Bellman-Zadeh scheme. We consider the formalization of subjective goals and the choice of membership functions for the decisions depending on subjective goals. We study the arrangement of these functions into an intersubjective membership function. The function is constructed for a resulting decision, which is chosen from a set of feasible decisions. The choice of the final intersubjective decision is discussed. All the issues are exemplified by a specific technological problem. The considered concept of solving technological problems under conditions of fuzzy goals allows one to choose the most efficient decisions from a set of feasible ones. These decisions correspond to the stated goals. The concept allows one to reduce human participation in automated design. This concept can be used to develop algorithms and design programs for forging numerous types of forged parts.

  19. Anisotropy effects during dwell-fatigue caused by δ-phase orientation in forged Inconel 718

    International Nuclear Information System (INIS)

    Saarimäki, Jonas; Colliander, Magnus Hörnqvist; Moverare, Johan J.

    2017-01-01

    Inconel 718 is a commonly used superalloy for turbine discs in the gas turbine industry. Turbine discs are often subjected to dwell-fatigue as a result of long constant load cycles. The effect of anisotropy on dwell-fatigue cracking in forged turbine discs have not yet been thoroughly investigated. Crack propagation behaviour was characterised using compact tension (CT) samples cut in different orientations from a real turbine disc forging. Samples were also cut in two different thicknesses in order to investigate the influence of plane strain and plane stress condition on the crack propagation rates. The samples were subjected to dwell-fatigue tests at 550 °C with 90 s or 2160 s dwell-times at maximum load. Microstructure characterisation was done using scanning electron microscopy (SEM) techniques such as electron channelling contrast imaging (ECCI), electron backscatter diffraction (EBSD), and light optical microscopy (LOM). The forged alloy exhibits strong anisotropic behaviour caused by the non-random δ-phase orientation. When δ-phases were oriented perpendicular compared to parallel to the loading direction, the crack growth rates were approximately ten times faster. Crack growth occurred preferably in the interface between the γ-matrix and the δ-phase.

  20. Simulative Testing of Friction and Lubrication in Cold Forging of Steel and Aluminum

    DEFF Research Database (Denmark)

    Ceron, Ermanno; Bay, Niels; Aida, Tetsuo

    2012-01-01

    A new, simulative test of friction and lubrication in cold forging is developed by the authors. The test is based on a backward can extrusion process in which the workpiece rotates relatively to the conical punch. An analytical model is presented determining the friction stress from the measured ...... coating plus MoS2 and single bathe lubrication with PULS and aluminum provided with 6 different lubricant systems. The new test is so severe, that it is possible to break down the best lubrication systems for cold forging of steel and aluminum.......A new, simulative test of friction and lubrication in cold forging is developed by the authors. The test is based on a backward can extrusion process in which the workpiece rotates relatively to the conical punch. An analytical model is presented determining the friction stress from the measured...... torque during testing combined with an analysis of the sliding velocity distribution along the punch nose. The latter is determined by FE analysis of the test. Results show friction stress for unalloyed low C-steel provided with different types of lubricants, i.e. phosphate coating plus soap, phosphate...

  1. Open die forging of large shafts with porosity defects – physical and numerical modelling

    DEFF Research Database (Denmark)

    Christiansen, Peter; Hattel, Jesper Henri; Bay, Niels

    2013-01-01

    The aim and scope of this paper is centered to analyze the influence of the geometry of V-shaped dies on the closure of internal centerline porosity defects in ingots during multistep open-die forging. The investigation is performed with small scale physical models made from lead using V-shaped d......The aim and scope of this paper is centered to analyze the influence of the geometry of V-shaped dies on the closure of internal centerline porosity defects in ingots during multistep open-die forging. The investigation is performed with small scale physical models made from lead using V......-shaped dies with 90o and 120o and a reference pair of flat parallel platens. Holes drilled through the center of these preforms are produced to mimic centerline porosity in full scale cast ingots and intermediate rotation of the preforms replicate a multi-stage forging sequence under laboratory testing...... conditions. The presentation is supported by finite element modelling using an in-house developed computer program and the overall investigation shows that better results in closure of centerline defects are obtained with a V-shaped die with 120º die angle....

  2. The coarsening effect of SA508-3 steel used as heavy forgings material

    Directory of Open Access Journals (Sweden)

    Dingqian Dong

    2015-01-01

    Full Text Available SA508Gr.3 steel is popularly used to produce core unit of nuclear power reactors due to its outstanding ability of anti-neutron irradiation and good fracture toughness. The forging process takes important role in manufacturing to refine the grain size and improve the material properties. But due to their huge size, heavy forgings cannot be cooled down quickly, and the refined grains usually have long time to grow in high temperature conditions. If the forging process is not adequately scheduled or implemented, very large grains up to millimetres in size may be found in this steel and cannot be eliminated in the subsequent heat treatment. To fix the condition which may causes the coarsening of the steel, hot upsetting experiments in the industrial production environment were performed under different working conditions and the corresponding grain sizes were measured and analysed. The observation showed that the grain will abnormally grow if the deformation is less than a critical value. The strain energy takes a critical role in the grain evolution. If dynamic recrystallization consumes the strain energy as much as possible, the normal grains will be obtained. While if not, the stored strain energy will promote abnormal growth of the grains.

  3. Wear Improvement of Tools in the Cold Forging Process for Long Hex Flange Nuts

    Directory of Open Access Journals (Sweden)

    Shao-Yi Hsia

    2015-09-01

    Full Text Available Cold forging has played a critical role in fasteners and has been widely used in automotive production, manufacturing, aviation and 3C (Computer, Communication, and Consumer electronics. Despite its extensive use in fastener forming and die design, operator experience and trial and error make it subjective and unreliable owing to the difficulty of controlling the development schedule. This study used finite element analysis to establish and simulate wear in automotive repair fastener manufacturing dies based on actual process conditions. The places on a die that wore most quickly were forecast, with the stress levels obtained being substituted into the Archard equation to calculate die wear. A 19.87% improvement in wear optimization occurred by applying the Taguchi quality method to the new design. Additionally, a comparison of actual manufacturing data to simulations revealed a nut forging size error within 2%, thereby demonstrating the accuracy of this theoretical analysis. Finally, SEM micrographs of the worn surfaces on the upper punch indicate that the primary wear mechanism on the cold forging die for long hex flange nuts was adhesive wear. The results can simplify the development schedule, reduce the number of trials and further enhance production quality and die life.

  4. Plutonium Immobilization Project Binder Burnout and Sintering Studies (Milestone 6.6a)

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, G.

    1999-10-28

    The Plutonium Immobilization Team has developed an integrated test program to understand and optimize the controlling variables for the sintering step of the plutonium immobilization process. Sintering is the key process step that controls the product minerology. It is expected that the sintering will be the limiting process step that controls the throughput of the production line. The goal of the current sintering test program is to better understand factors that affect the sintering process.

  5. Plutonium Immobilization Project Binder Burnout and Sintering Studies (Milestone 6.6a)

    International Nuclear Information System (INIS)

    Chandler, G.

    1999-01-01

    The Plutonium Immobilization Team has developed an integrated test program to understand and optimize the controlling variables for the sintering step of the plutonium immobilization process. Sintering is the key process step that controls the product mineralogy. It is expected that the sintering will be the limiting process step that controls the throughput of the production line. The goal of the current sintering test program is to better understand factors that affect the sintering process

  6. Sintering and electrical properties of strontium-doped lanthanum manganite

    Energy Technology Data Exchange (ETDEWEB)

    Tarrago, Diego Pereira; Sousa, Vania Caldas de [Universidade Federal do Rio Grande do Sul (LABIOMAT/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Biomateriais], Email: dptarrago@gmail.com; Moreno Buriel, Berta; Chinarro Martini, Eva; Jurado Egea, Jose Ramon [Consejo Superior de Investigaciones Cientificas (ICV/CSIC), Madrid (Spain). Inst. de Ceramica y Vidrio; Malfatti, Celia de Fraga [Universidade Federal do Rio Grande do Sul (LAPEC/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Pesquisa em Corrosao

    2010-07-01

    Lanthanum strontium manganites (LSM) are potential materials for cathode applications in solid oxide fuel cells (SOFC) due to their good catalytic activity, chemical stability and compatibility with electrolyte materials in high temperatures. The sinterability of single phase La{sub 1-x}Sr{sub x}Mn{sub O3} (x=0.18) perovskite powders and the electrical properties of the resulting samples are analyzed in this study. Using a heating microscope, the powders were pressed and sintered at different pressures and temperatures, resulting in an open porosity of 33.36% when compacted at 125 MPa and sintered at 1200 degree C. Top and cross-section s canning electron microscopy (SEM) micrographs revealed interconnected pores in the sintered body and, hence, a suitable microstructure for the application. The activation energy for conductance was 0.04 eV and the tested LSM bulk started to exhibit adequate electrical properties at about 500 degree C. (author)

  7. Zone refining of sintered, microwave-derived YBCO superconductors

    International Nuclear Information System (INIS)

    Warrier, K.G.K.; Varma, H.K.; Mani, T.V.; Damodaran, A.D.; Balachandran, U.

    1993-07-01

    Post-sintering treatments such as zone melting under thermal gradient has been conducted on sintered YBCO tape cast films. YBCO precursor powder was derived through decomposition of a mixture of nitrates of cations in a microwave oven for ∼4 min. The resulting powder was characterized and made into thin sheets by tape casting and then sintered at 945 C for 5 h. The sintered tapes were subjected to repeated zone refining operations at relatively high speeds of ∼30 mm/h. A microstructure having uniformly oriented grains in the a-b plane throughout the bulk of the sample was obtained by three repeated zone refining operations. Details of precursor preparation, microwave processing and its advantages, zone refining conditions, and microstructural features are presented in this paper

  8. Quartz crystal reinforced quartz glass by spark plasma sintering

    International Nuclear Information System (INIS)

    Torikai, D.; Barazani, B.; Ono, E.; Santos, M.F.M.; Suzuki, C.K.

    2011-01-01

    The Spark Plasma Sintering presents fast processing time when compared to conventional sintering techniques. This allows to control the grain growth during sintering as well as the diffusion rate of a multi-material compounds, and make possible obtainment of functionally graded materials and nanostructured compounds. Powders of high purity silica glass and crystalline silica were sintered in a SPS equipment at temperatures around 1350° C, i.e., above the softening temperature of silica glass and below the melting temperature of quartz crystal. As a result, glass ceramics with pure silica glass matrix reinforced with crystalline alpha-quartz grains were fabricated at almost any desired range of composition, as well as controlled size of the crystalline reinforcement. X-ray diffraction and density measurements showed the possibility to manufacture a well controlled density and crystallinity glass-ceramic materials. (author)

  9. Electric Field-Assisted Pressureless Sintering of Ceramic Protonic Conductors

    DEFF Research Database (Denmark)

    Muccillo, R.; Esposito, Vincenzo; de Florio, D. Z.

    2017-01-01

    Gadolinium, yttrium and samarium-doped barium cerate pressed pellets were submitted to flash sintering experiments isothermally in the temperature range 800-1300oC under 200 V cm-1 electric field. The pellets were positioned inside a dilatometer furnace with Pt-Ir electrodes connected either...... to a power supply or to an impedance analyzer to evaluate the bulk and the grain boundary contributions to the electrical resistivity. Near full density was achieved in the sintered samples. The combined results of dilatometry and impedance measurements in conventionally and flash sintered specimens show...... substantial improvement of the electrical conductivity. Joule heating is assumed to be the primary effect for sintering. Improved grain-to-grain contact and the removal of depleted chemical species due to Joule heating at the space charge region are proposed, respectively, as the reasons for the decrease...

  10. Onset conditions for flash sintering of UO2

    Science.gov (United States)

    Raftery, Alicia M.; Pereira da Silva, João Gustavo; Byler, Darrin D.; Andersson, David A.; Uberuaga, Blas P.; Stanek, Christopher R.; McClellan, Kenneth J.

    2017-09-01

    In this work, flash sintering was demonstrated on stoichiometric and non-stoichiometric uranium dioxide pellets at temperatures ranging from room temperature (26 °C) up to 600 °C . The onset conditions for flash sintering were determined for three stoichiometries (UO2.00, UO2.08, and UO2.16) and analyzed against an established thermal runaway model. The presence of excess oxygen was found to enhance the flash sintering onset behavior of uranium dioxide, lowering the field required to flash and shortening the time required for a flash to occur. The results from this study highlight the effect of stoichiometry on the flash sintering behavior of uranium dioxide and will serve as the foundation for future studies on this material.

  11. Foam glass obtained through high-pressure sintering

    DEFF Research Database (Denmark)

    Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

    2018-01-01

    are subjected to a second heat treatment above the glass transition temperature at atmospheric pressure. This heat treatment causes expansion of the pores due to high internal gas pressure. We found that the foaming ability strongly depends on the gas pressure applied during sintering, and on the kinetic......Foam glasses are usually prepared through a chemical approach, that is, by mixing glass powder with foaming agents, and heating the mixture to a temperature above the softening point (106.6 Pa s) of the glass. The foaming agents release gas, enabling expansion of the sintered glass. Here, we use...... a physical foaming approach to prepare foam glass. First, closed pores filled with inert gases (He, Ar, or N2) are physically introduced into a glass body by sintering cathode ray tube (CRT) panel glass powder at high gas pressure (5‐25 MPa) at 640°C and, then cooled to room temperature. The sintered bodies...

  12. Efficient Radiation Shielding Through Direct Metal Laser Sintering

    Data.gov (United States)

    National Aeronautics and Space Administration — We have developed a method for efficient component-level radiation shielding that can be printed by direct metal laser sintering (DMLS) from files generated by the...

  13. Non-pressurized sintered silicon carbide with titanium carbide reinforcement

    International Nuclear Information System (INIS)

    Adler, J.

    1992-01-01

    A non-pressurized compression of SiC-TiC composite materials can be achieved via liquid phase sintering by the application of oxidic additives. Materials with TiC proportions up to 40% by volume of TiC and densities of 97 to 98% TD were produced at sintering temperatures around 1875 C. With SiC sintered in the liquid phase an increase of toughness at fracture of 80% compared with conventionally non-pressurized sintered SiC was achieved with B/C additive. No further increase could be achieved by the addition of TiC particles. However, the oxidation resistance at 1200 C was worsened. (orig.) [de

  14. Pressureless sintering behavior of injection molded alumina ceramics

    Directory of Open Access Journals (Sweden)

    Liu W.

    2014-01-01

    Full Text Available The pressureless sintering behaviors of two widely used submicron alumina (MgOdoped and undoped with different solid loadings produced by injection molding have been studied systematically. Regardless of the sinterability of different powders depending on their inherent properties, solid loading plays a critical role on the sintering behavior of injection molded alumina, which greatly determines the densification and grain size, and leads to its full densification at low temperatures. As compared to the MgO-doped alumina powder, the undoped specimens exhibit a higher sinterability for its smaller particle size and larger surface area. While full densification could be achieved for MgO-doped powders with only a lower solid loading, due to the fact that MgO addition can reduce the detrimental effect of the large pore space on the pore-boundary separation.

  15. Modeling constrained sintering of bi-layered tubular structures

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Kothanda Ramachandran, Dhavanesan; Ni, De Wei

    2015-01-01

    Constrained sintering of tubular bi-layered structures is being used in the development of various technologies. Densification mismatch between the layers making the tubular bi-layer can generate stresses, which may create processing defects. An analytical model is presented to describe...... the densification and stress developments during sintering of tubular bi-layered samples. The correspondence between linear elastic and linear viscous theories is used as a basis for derivation of the model. The developed model is first verified by finite element simulation for sintering of tubular bi-layer system....... Furthermore, the model is validated using densification results from sintering of bi-layered tubular ceramic oxygen membrane based on porous MgO and Ce0.9Gd0.1O1.95-d layers. Model input parameters, such as the shrinkage kinetics and viscous parameters are obtained experimentally using optical dilatometry...

  16. Verification of the Skorohod-Olevsky Viscous Sintering (SOVS) Model

    Energy Technology Data Exchange (ETDEWEB)

    Lester, Brian T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-11-16

    Sintering refers to a manufacturing process through which mechanically pressed bodies of ceramic (and sometimes metal) powders are heated to drive densification thereby removing the inherit porosity of green bodies. As the body densifies through the sintering process, the ensuing material flow leads to macroscopic deformations of the specimen and as such the final configuration differs form the initial. Therefore, as with any manufacturing step, there is substantial interest in understanding and being able to model the sintering process to predict deformation and residual stress. Efforts in this regard have been pursued for face seals, gear wheels, and consumer products like wash-basins. To understand the sintering process, a variety of modeling approaches have been pursued at different scales.

  17. 2016 Accomplishments. Tritium aging studies on stainless steel. Forging process effects on the fracture toughness properties of tritium-precharged stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Michael J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-01-01

    Forged austenitic stainless steels are used as the materials of construction for pressure vessels designed to contain tritium at high pressure. These steels are highly resistant to tritium-assisted fracture but their resistance can depend on the details of the forging microstructure. During FY16, the effects of forging strain rate and deformation temperature on the fracture toughness properties of tritium-exposed-and-aged Type 304L stainless steel were studied. Forgings were produced from a single heat of steel using four types of production forging equipment – hydraulic press, mechanical press, screw press, and high-energy-rate forging (HERF). Each machine imparted a different nominal strain rate during the deformation. The objective of the study was to characterize the J-Integral fracture toughness properties as a function of the industrial strain rate and temperature. The second objective was to measure the effects of tritium and decay helium on toughness. Tritium and decay helium effects were measured by thermally precharging the as-forged specimens with tritium gas at 34.5 MPa and 350°C and aging for up to five years at -80°C to build-in decay helium prior to testing. The results of this study show that the fracture toughness properties of the as-forged steels vary with forging strain rate and forging temperature. The effect is largely due to yield strength as the higher-strength forgings had the lower toughness values. For non-charged specimens, fracture toughness properties were improved by forging at 871°C versus 816°C and Screw-Press forgings tended to have lower fracture toughness values than the other forgings. Tritium exposures reduced the fracture toughness values remarkably to fracture toughness values averaging 10-20% of as-forged values. However, forging strain rate and temperature had little or no effect on the fracture toughness after tritium precharging and aging. The result was confirmed by fractography which indicated that fracture modes

  18. Ash chemistry and sintering, verification of the mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Hupa, M.; Skrifvars, B.J. [Aabo Akademi, Turku (Finland)

    1996-12-01

    In this project four sintering mechanisms have been studied, i.e., partial melting with a viscous liquid, partial melting with a non-viscous liquid, chemical reaction sintering and solid state sintering. The work has aimed at improving the understanding of ash sintering mechanisms and quantifying their role in combustion and gasification. The work has been oriented in particular on the understanding of biomass ash behavior. The work has not directly focused on any specific technical application. However, results can also be applied on other fuels such as brown coal, petroleum coke, black liquor and different types of wastes (PDF, RDF, MSW). In one part of study the melting behavior was calculated for ten biomass ashes and compared with lab measurements of sintering tendencies. The comparison showed that the T{sub 15} temperatures, i.e. those temperatures at which the ashes contained 15 % molten phase, correlated fairly well with the temperature at which the sintering measurements detected sintering. This suggests that partial melting can be predicted fairly accurate for some ashes already with the today existing thermodynamic calculation routines. In some cases, however the melting calculations did not correlate with the detected sintering temperatures. In a second part detailed measurements on ash behavior was conducted both in a semi full scale CFB and a lab scale FBC. Ashes and deposits were collected and analyzed in several different ways. These analyses show that the ash chemistry shifts radically when the fuel is shifted. Fuels with silicate based ashes behaved totally different than those with an oxide or salt based ash. The chemistry was also affected by fuel blending. The ultimate goal has been to be able to predict the ash thermal behavior during biomass thermal conversion, using the fuel and ash elemental analyses and a few operational key parameters as the only input data. This goal has not yet today been achieved. (author)

  19. Low temperature sintering of fluorapatite glass-ceramics.

    Science.gov (United States)

    Denry, Isabelle; Holloway, Julie A

    2014-02-01

    Fluorapatite glass-ceramics have been shown to be excellent candidates as scaffold materials for bone grafts, however, scaffold production by sintering is hindered by concurrent crystallization of the glass. Objective, our goal was to investigate the effect of Ca/Al ratio on the sintering behavior of Nb-doped fluorapatite-based glasses in the SiO2-Al2O3-P2O5-MgO-Na2O-K2O-CaO-CaF2 system. Methods, glass compositions with Ca/Al ratio of 1 (A), 2 (B), 4 (C) and 19 (D) were prepared by twice melting at 1525°C for 3h. Glasses were either cast as cylindrical ingots or ground into powders. Disk-shaped specimens were prepared by either sectioning from the ingots or powder-compacting in a mold, followed by heat treatment at temperatures ranging between 700 and 1050°C for 1h. The density was measured on both sintered specimens and heat treated discs as controls. The degree of sintering was determined from these measurements. Results and Significance XRD showed that fluorapatite crystallized in all glass-ceramics. A high degree of sintering was achieved at 775°C for glass-ceramic D (98.99±0.04%), and 900°C for glass-ceramic C (91.31±0.10). Glass-ceramics A or B were only partially sintered at 1000°C (63.6±0.8% and 74.1±1.5%, respectively). SEM revealed a unique microstructure of micron-sized spherulitic fluorapatite crystals in glass-ceramics C and D. Increasing the Ca/Al ratio promoted low temperature sintering of fluorapatite glass-ceramics, which are traditionally difficult to sinter. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Process for preparing sintered uranium dioxide nuclear fuel

    International Nuclear Information System (INIS)

    Carter, R.E.

    1975-01-01

    Uranium dioxide is prepared for use as fuel in nuclear reactors by sintering it to the desired density at a temperature less than 1300 0 C in a chemically controlled gas atmosphere comprised of at least two gases which in equilibrium provide an oxygen partial pressure sufficient to maintain the uranium dioxide composition at an oxygen/uranium ratio of at least 2.005 at the sintering temperature. 7 Claims, No Drawings

  1. Corrosion Properties of Sintered and Wrought Stainless Seel

    DEFF Research Database (Denmark)

    Mathiesen, Troels; Maahn, Ernst Emanuel

    1997-01-01

    The corrosion properties of a range of stainless steels produced by powder metallurgy (PM) are compared with wrought AISI304 and AISI316 Steel. Characterisation of the passivation properties in 0.5M H2SO4 and pittingresistance in 0.3% chloride solution by polarisation show properties...... of the sintered PM150 that are comparable or better than those of wrought 316 steel depending on the applied sintering technique....

  2. Low temperature sintering of fluorapatite glass-ceramics

    Science.gov (United States)

    Denry, Isabelle; Holloway, Julie A.

    2014-01-01

    Fluorapatite glass-ceramics have been shown to be excellent candidates as scaffold materials for bone grafts, however, scaffold production by sintering is hindered by concurrent crystallization of the glass. Our goal was to investigate the effect of Ca/Al ratio on the sintering behavior of Nb-doped fluorapatite-based glasses in the SiO2-Al2O3-P2O5-MgO-Na2O-K2O-CaO-CaF2 system. Glass compositions with Ca/Al ratio of 1 (A), 2 (B), 4 (C) and 19 (D) were prepared by twice melting at 1525°C for 3h. Glasses were either cast as cylindrical ingots or ground into powders. Disc-shaped specimens were prepared by either sectioning from the ingots or powder-compacting in a mold, followed by heat treatment at temperatures ranging between 700 and 1050°C for 1h. The density was measured on both sintered specimens and heat treated discs as controls. The degree of sintering was determined from these measurements. XRD showed that fluorapatite crystallized in all glass-ceramics. A high degree of sintering was achieved at 775°C for glass-ceramic D (98.99±0.04%), and 900°C for glass-ceramic C (91.31±0.10). Glass-ceramics A or B were only partially sintered at 1000°C (63.6±0.8% and 74.1±1.5%, respectively). SEM revealed a unique microstructure of micron-sized spherulitic fluorapatite crystals in glass-ceramics C and D. Increasing the Ca/Al ratio promoted low temperature sintering of fluorapatite glass-ceramics, which are traditionally difficult to sinter. PMID:24252652

  3. Properties of Bulk Sintered Silver As a Function of Porosity

    Energy Technology Data Exchange (ETDEWEB)

    Wereszczak, Andrew A [ORNL; Vuono, Daniel J [ORNL; Wang, Hsin [ORNL; Ferber, Mattison K [ORNL; Liang, Zhenxian [ORNL

    2012-06-01

    This report summarizes a study where various properties of bulk-sintered silver were investigated over a range of porosity. This work was conducted within the National Transportation Research Center's Power Device Packaging project that is part of the DOE Vehicle Technologies Advanced Power Electronics and Electric Motors Program. Sintered silver, as an interconnect material in power electronics, inherently has porosity in its produced structure because of the way it is made. Therefore, interest existed in this study to examine if that porosity affected electrical properties, thermal properties, and mechanical properties because any dependencies could affect the intended function (e.g., thermal transfer, mechanical stress relief, etc.) or reliability of that interconnect layer and alter how its performance is modeled. Disks of bulk-sintered silver were fabricated using different starting silver pastes and different sintering conditions to promote different amounts of porosity. Test coupons were harvested out of the disks to measure electrical resistivity and electrical conductivity, thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and yield stress. The authors fully recognize that the microstructure of processed bulk silver coupons may indeed not be identical to the microstructure produced in thin (20-50 microns) layers of sintered silver. However, measuring these same properties with such a thin actual structure is very difficult, requires very specialized specimen preparation and unique testing instrumentation, is expensive, and has experimental shortfalls of its own, so the authors concluded that the herein measured responses using processed bulk sintered silver coupons would be sufficient to determine acceptable values of those properties. Almost all the investigated properties of bulk sintered silver changed with porosity content within a range of 3-38% porosity. Electrical resistivity, electrical conductivity

  4. Impact strength of sintered astaloy CrM powders

    International Nuclear Information System (INIS)

    Kazior, J.; Ploszczak, J.; Nykiel, M.; Pieczonka, T.

    2003-01-01

    In this paper results of a series of impact tests on sintered Astaloy CrM powders alloys modified by boron are presented and discussed. Boron in different forms, i.e. as elemental boron powder, boron carbide B 4 C powder or mixture of boron and carbon elemental powders, was used in different weight percentage to activate sintering of Astaloy CrM powder and to increase hardenability, with aim of increasing impact strength in view of structural applications. (author)

  5. Enhanced Sintering of Boron Carbide-Silicon Composites by Silicon

    Science.gov (United States)

    Zeng, Xiaojun; Liu, Weiliang

    2016-11-01

    Boron carbide (B4C)-silicon (Si) composites have been prepared by aqueous tape casting, laminating, and spark plasma sintering (SPS). The influences of silicon (Si) content on the phases, microstructure, sintering properties, and mechanical properties of the obtained B4C-Si composites are studied. The results indicate that the addition of Si powder can act as a sintering aid and contribute to the sintering densification. The addition of Si powder can also act as a second phase and contribute to the toughening for composites. The relative density of B4C-Si composites samples with adding 10 wt.% Si powder prepared by SPS at 1600 °C and 50 MPa for 8 min is up to 98.3%. The bending strength, fracture toughness, and Vickers hardness of the sintered samples are 518.5 MPa, 5.87 MPa m1/2, and 38.9 GPa, respectively. The testing temperature-dependent high-temperature bending strength and fracture toughness can reach a maximum value at 1350 °C. The B4C-Si composites prepared at 1600, 1650, and 1700 °C have good high-temperature mechanical properties. This paper provides a facile low-temperature sintering route for B4C ceramics with improved properties.

  6. Bending Behavior of Porous Sintered Stainless Steel Fiber Honeycombs

    Science.gov (United States)

    Zou, Shuiping; Wan, Zhenping; Lu, Longsheng; Tang, Yong

    2017-02-01

    A novel porous honeycomb-type substrate has been developed using solid-state sintering stainless steel fibers. The porous sintered stainless steel fiber honeycombs (PSSSFH) are composed of a skeleton of sintered stainless steel fibers, three-dimensionally interconnected porous structures and multiple parallel microchannels. The bending behavior of the PSSSFH is investigated using three-point bending tests. Four stages, including an elastic stage, a yielding stage with a plateau, a hardening stage and a failure stage, are observed during the bending process of the PSSSFH. In the initial yielding stage, the bending forces increase slowly with displacement increasing, and then a yielding plateau follows, which is unique compared with other porous materials. Moreover, the structure parameters of the PSSSFH are varied to investigate the influence on the bending strength. It is determined that the multiple parallel microchannels can enhance the bending strength of porous stainless steel fiber sintered substrates (PSSFSS) and do not influence the variation trend of bending strength of PSSFSS with porosity increasing. The open ratio is conducive to increasing the bending strength, and the microchannel diameters ranging from 0.5 mm to 1.5 mm have little influence on the bending strength. In addition, both the increasing of sintering temperature and sintering time can strengthen the PSSSFH.

  7. Industrial Sintering of Uranium Oxide in a Continuous Furnace

    International Nuclear Information System (INIS)

    Hauser, R.; Porneuf, A.

    1963-01-01

    Under a USAEC-EURATOM research contract, CICAF (Compagnie industrielle de combustibles atomiques frittes) was asked by the French Atomic Energy Commission to design and construct a continuous furnace sintering under a reducing atmosphere at high temperature. The characteristic features of the furnace are automatic operation, rigorous control of presintering and sintering atmospheres, flexibility of temperature regulation so that the thermal cycle can be adjusted to the product to be sintered and high output (5 t of uranium oxide per month). It can operate continuously up to 1700 deg. C, the presintering taking place at a lower temperature (800 deg. C) in a preliminary furnace which forms an integral part of the whole. The sintering atmosphere is cracked ammonia or pure hydrogen; the presintering atmosphere is a mixture o f about 10% hydrogen and 90% nitrogen. The sintered pellets densify to above 97% of theoretical density, with a total dispersion of less than 1%. Structurally, they are equi-axed grains of about 10μm. It was established that the stoichiometric variation of the uranium oxide sintered in a continuous furnace was less than 0.005. (author) [fr

  8. Manufacture of sintered bricks of high density from beryllium oxide

    International Nuclear Information System (INIS)

    Pointud, R.; Rispal, Ch.; Le Garec, M.

    1959-01-01

    Beryllium oxide bricks of nuclear purity 100 x 100 x 50 and 100 x 100 x 100 mm of very high density (between 2.85 and 3.00) are manufactured by sintering under pressure in graphite moulds at temperatures between 1,750 and 1,850 deg. C, and under a pressure of 150 kg/cm 2 . The physico-chemical state of the saw material is of considerable importance with regard to the success of the sintering operation. In addition, a study of the sintering of a BeO mixture with 3 to 5 per cent of boron introduced in the form of boric acid, boron carbide or elementary boron shows that high densities can only be obtained by sintering under pressure. For technical reasons of manufacture, only the mixture based on boron carbide is used. The sintering is carried out in graphite moulds at 1500 deg. C under 150 kg/cm 2 pressure, and bricks can be obtained with density between 2,85 and 2,90. Laboratory studies and the industrial manufacture of various sinters are described in detail. (author) [fr

  9. Uniaxial ratcheting behavior of sintered nanosilver joint for electronic packaging

    International Nuclear Information System (INIS)

    Chen, Gang; Yu, Lin; Mei, Yunhui; Li, Xin; Chen, Xu; Lu, Guo-Quan

    2014-01-01

    Uniaxial ratcheting behavior and the fatigue life of sintered nanosilver joint were investigated at room temperature. All tests were carried out under stress-controlled mode. Force–displacement data were recorded during the entire fatigue lifespan by a non-contact displacement detecting system. Effects of stress amplitude, mean stress, stress rate, and stress ratio on the uniaxial ratcheting behavior of the sintered nanosilver joint were discussed. Stress-life (S–N) curves of the sintered joints were also obtained. The Smith–Watson–Topper (SWT) model, the Gerber model and the modified Goodman model, all of which took effect of mean stress into consideration, were compared for predicting the fatigue life of the sintered joint. Both the ratcheting strain and its rate increased with increasing stress amplitude or mean stress. The increase in stress amplitude and mean stress both reduced the fatigue life of the sintered joint, while the fatigue life prolonged with the increase in stress rate and stress ratio. The modified Goodman model predicted the fatigue life of the sintered joints well

  10. Effect of sintering temperature on optical properties and microstructure of translucent zirconia prepared by high-pressure spark plasma sintering

    Directory of Open Access Journals (Sweden)

    Haibin Zhang, Byung-Nam Kim, Koji Morita, Hidehiro Yoshida Keijiro Hiraga and Yoshio Sakka

    2011-01-01

    Full Text Available Aiming to characterize the effect of sintering temperature on transparency of zirconia, we have evaluated the optical properties and microstructure of translucent cubic zirconia prepared by high-pressure spark plasma sintering (SPS at 1000–1200 circleC. Color centers (oxygen vacancies with trapped electrons and residual pores were primary defects in the samples. In SPS samples, the total forward transmittance and in-line transmittance are mainly affected by color centers with a limited contribution from residual pores; in contrast, the changes in reflectance are only related to the porosity. The amounts of color centers and residual pores increase with sintering temperature that reduces the total forward and in-line transmittance of the as-sintered zirconia. Annealing in oxidizing atmosphere improves the total forward and in-line transmittance. During the annealing, the concentration of color centers decreases but the porosity increases.

  11. Effect Of Compaction Pressure And Sintering Temperature On The Liquid Phase Sintering Behavior Of Al-Cu-Zn Alloy

    Directory of Open Access Journals (Sweden)

    Lee S.H.

    2015-06-01

    Full Text Available The liquid phase sintering characteristics of Al-Cu-Zn alloy were investigated with respect to various powder metallurgy processing conditions. Powders of each alloying elements were blended to form Al-6Cu-5Zn composition and compacted with pressures of 200, 400, and 600 MPa. The sintering process was performed at various temperatures of 410, 560, and 615°C in N2 gas atmosphere. Density and micro-Vickers hardness measurements were conducted at different processing stages, and transverse rupture strength of sintered materials was examined for each condition, respectively. The microstructure was characterized using optical microscope and scanning electron microscopy. The effect of Zn addition on the liquid phase sintering behavior during P/M process of the Al-Cu-Zn alloy was also discussed in detail.

  12. Thermal Analysis of Sintered Silver Nanoparticles Film

    Directory of Open Access Journals (Sweden)

    M. Keikhaie

    2014-07-01

    Full Text Available Thin bonded films have many applications in antireflection and reflection coating, insulating and conducting films and semiconductor industries. Thermal conductivity is one of the most important parameter for power packaging since the thermal resistance of the interconnections is directly related to the heat removal capability and thermal management of the power package. The defects in materials play very important role on the effective thermal conductivity. In this paper, finite element method (FEM was utilized to simulate the effect of pores on the effective thermal conductivity of sintered silver nanoparticles film. The simulation results indicate that the effective thermal conductivity of film is different at different directions and would be enhanced when the pore angle is 90. The simulation results will help us to further understand the heat transfer process across highly porous structures and will provide us a powerful guide to design coating with high thermal insulation or conductor property. Because of there is no similar experimental data for this simulation results, this paper is a comparative work among three different models.

  13. Polymer powders for selective laser sintering (SLS)

    Science.gov (United States)

    Schmid, Manfred; Amado, Antonio; Wegener, Konrad

    2015-05-01

    Selective Laser Sintering (SLS) is close to be accepted as a production technique (Additive Manufacturing). However, one problem limiting employment of SLS for additive manufacturing in a wide-ranging industrial scope is the narrow variety of applicable polymers. The commonly applied SLS powder to date is polyamide 12 (PA 12). PA 12 or ccompounds of PA 12 (dry blends) are approximately 90 % of complete industrial consumption. The remaining small quantity is distributed on polyamide 11 (PA11) and some other `exotic' polymers (TPU, PEBA, P(E)EK). Industry is awaiting commodity polymers like polypropylene (PP) or polyethylene (PE) crucial to open new market segments. But several approaches launching those polymers failed. But what are the reasons for the difficulties in developing new SLS powders? The contribution is to answer this and highlights the combination of intrinsic and extrinsic polymer properties necessary to generate a polymer powder promising for SLS application. Particle shape, powder distribution, thermal, rheological and optical requirements must be considered and only a particularly controlled property combination leads to successful SLS implementation. Thermal behavior, particle shape and -distribution is discussed in detail, although the other properties can't be disregarded for providing new commercially successful SLS powder finally.

  14. Microwave combustion and sintering without isostatic pressure

    International Nuclear Information System (INIS)

    Ebadian, M.A.

    1998-01-01

    In recent years interest has grown rapidly in the application of microwave energy to the processing of ceramics, composites, polymers, and other materials. Advances in the understanding of microwave/materials interactions will facilitate the production of new ceramic materials with superior mechanical properties. One application of particular interest is the use of microwave energy for the mobilization of uranium for subsequent redeposition. Phase III (FY98) will focus on the microwave assisted chemical vapor infiltration tests for mobilization and redeposition of radioactive species in the mixed sludge waste. Uranium hexachloride and uranium (IV) borohydride are volatile compounds for which the chemical vapor infiltration procedure might be developed for the separation of uranium. Microwave heating characterized by an inverse temperature profile within a preformed ceramic matrix will be utilized for CVI using a carrier gas. Matrix deposition is expected to commence from the inside of the sample where the highest temperature is present. The preform matrix materials, which include aluminosilicate based ceramics and silicon carbide based ceramics, are all amenable to extreme volume reduction, densification, and vitrification. Important parameters of microwave sintering such as frequency, power requirement, soaking temperature, and holding time will be investigated to optimize process conditions for the volatilization of uranyl species using a reactive carrier gas in a microwave chamber

  15. Damage Behavior of Sintered Fiber Felts

    Directory of Open Access Journals (Sweden)

    Nicolas Lippitz

    2015-04-01

    Full Text Available The reduction of aircraft noise is important due to a rising number of flights and the growth of urban centers close to airports. During landing, a significant part of the noise is generated by flow around the airframe. To reduce that noise porous trailing edges are investigated. Ideally, the porous materials should to be structural materials as well. Therefore, the mechanical properties and damage behavior are of major interest. The aim of this study is to show the change of structure and the damage behavior of sintered fiber felts, which are promising materials for porous trailing edges, under tensile loading using a combination of tensile tests and three dimensional computed tomography scans. By stopping the tensile test after a defined stress or strain and scanning the sample, it is possible to correlate structural changes and the development of damage to certain features in the stress-strain curve and follow the damage process with a high spatial resolution. Finally, the correlation between material structure and mechanical behavior is demonstrated.

  16. Effect of interfacial friction during forging of solid powder discs of ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    1 and S KUMAR. 2. 1Applied Mechanics Department, and 2Production Engineering Department, Birla. Institute of Technology, Mesra, Ranchi 835 215, India ..... Proc. Int. Tribology Conference, The Institutrion of Engineers, p 346. Kumar S, Jha A K, Singh R K, Singh S 2001 Sintered preforms adds better value to aerospace.

  17. High speed forging of solid powder discs of large slenderness ratio

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    manufacturing processes such as casting, machining etc. In this new technology, sintered porous powder preforms are used as starting materials in metal forming processes. Metal- powder products manufactured by ... because of the introduction of new and fast deformation processes. Since speed is an impor- tant factor ...

  18. Dry Sintered Metal Coating of Halloysite Nanotubes

    Directory of Open Access Journals (Sweden)

    James C. Nicholson

    2016-09-01

    Full Text Available Halloysite nanotubes (HNTs are a naturally-occurring aluminosilicate whose dimensions measure microns in length and tens of nanometers in diameter. Bonding defects between the alumina and silica lead to net negative and positive charges on the exterior and interior lumen, respectively. HNTs have been shown to enhance the material properties of polymer matrices and enable the sustained release of loaded chemicals, drugs, and growth factors. Due to the net charges, these nanotubes can also be readily coated in layered-depositions using the HNT exterior lumen’s net negative charge as the basis for assembly. These coatings are primarily done through wet chemical processes, the majority of which are limited in their use of desired chemicals, due to the polarity of the halloysite. Furthermore, this restriction in the type of chemicals used often requires the use of more toxic chemicals in place of greener options, and typically necessitates the use of a significantly longer chemical process to achieve the desired coating. In this study, we show that HNTs can be coated with metal acetylacetonates—compounds primarily employed in the synthesis of nanoparticles, as metal catalysts, and as NMR shift reagents—through a dry sintering process. This method was capable of thermally decaying the metal acetylacetonate, resulting in a free positively-charged metal ion that readily bonded to the negatively-charged HNT exterior, resulting in metallic coatings forming on the HNT surface. Our coating method may enable greater deposition of coated material onto these nanotubes as required for a desired application. Furthermore, the use of chemical processes using toxic chemicals is not required, thus eliminating exposure to toxic chemicals and costs associated with the disposal of the resultant chemical waste.

  19. Forging of eccentric co-extruded Al-Mg compounds and analysis of the interface strength

    Science.gov (United States)

    Förster, W.; Binotsch, C.; Awiszus, B.; Lehmann, T.; Müller, J.; Kirbach, C.; Stockmann, M.; Ihlemann, J.

    2016-03-01

    Within the subproject B3 of the Collaborative Research Center 692 it has been shown that Al-Mg compounds with a good bonding quality can be produced by hydrostatic coextrusion. During processing by forging, the aluminum sleeve is thinned in areas of high strains depending on the component geometry. To solve this problem an eccentric core arrangement during co-extrusion was investigated. Based on the results of FE-simulations, the experimental validation is presented in this work. Rods with an offset of 0.25, 0.5 and 0.75 mm were produced by eccentric hydrostatic co-extrusion. Ultrasonic testing was used to evaluate the bonding quality across the entire rods. For the forging investigations the basic process Rising was chosen. The still good bonding quality after forging was examined by dye penetrant testing and optical microscopy. For an optimal stress transfer between the materials across the entire component, a sufficient bonding between the materials is essential. To evaluate the interface strength, a special bending test was developed. For the conception of the bending specimens it was required to analyze the Rising specimens geometry. These analyses were performed using a reconstruction of the geometrical data based on computer tomography (CT) investigations. The comparison with the numerically deter-mined Rising specimen geometry shows good correlation. Parametric Finite Element Analyses of the bending test were used to develop the load case and the specimen geometry. By means of iterative adaption of load application, bearing and specimen geometry parameters, an advantageous stress state and experimentally applicable configuration were found. Based on this conception, the experimental setup was configured and bending tests were performed. The interface strength was deter-mined by the calculation of the maximum interlaminar interfacial tension stress using the experimental interface failure force and the bending FE model.

  20. Energy-efficiency in inductive heating of forging ingots; Energieeffizienz bei der induktiven Erwaermung von Schmiedebloecken

    Energy Technology Data Exchange (ETDEWEB)

    Padberg, Michael; Doetsch, Erwin [ABP Induction Systems, Dortmund (Germany)

    2012-03-15

    The continuously increasing importance of the CO{sub 2} balance and of conservation of resources is resulting in ever greater demands for high energy-efficiency in the process used for heating of forging ingots. Plant and process engineering play roles of parallel significance in the fulfillment of these requirements, and this article focuses on both in equal degree. The shares of the individual components in the overall energy consumption of an induction heating installation are therefore firstly determined, and their respective potentials for optimization then discussed. The quality of the heating process itself, and its optimum design for reduction of energy consumption, are then examined. (orig.)

  1. Influence of sulphur and phosphorus impurities on ductility of 25Kh2NMFA steel during forging

    International Nuclear Information System (INIS)

    Onishchenko, A.K.

    1989-01-01

    Using cylindrical samples of the 25Kh2NMFA steel with sulfur and phosphorus content in the range of 0.001-0.030%, tensile test with the rate of deformation 10 -3 s -1 at the temperatures of 800-1200 deg C has been conducted. Analysis of fracture foci and plasticity diagrams has shown, that to ensure ductility during forging and high mechanical properties, the content of sulfur and phosphorus impurities in the 25Kh2NMFA steel must not exceed 0.015%

  2. Audio Format Change From Analog to Digital Audio Using the Sony Sound Forge 9.0

    OpenAIRE

    Faisal Safrudin; Yulina Yulina, SKom, MMSI

    2007-01-01

    Changes in an audio analog to digital audio is not only useful in among the journalists or the journalists are also useful for general audiences though. In previous technology we encounter a lot of almost everyone uses the form of analog audio cassettes. Along with the development of technology, analog audio format is rarely used in the presence of digital audio, but it can be overcome by changing the format of analog audio to digital audio using Sony Sound Forge 9.0. The author will discuss ...

  3. Study of formation of aluminium billet in casting mold during continuous casting and forging

    International Nuclear Information System (INIS)

    Stulov, V.V.

    1997-01-01

    Aluminium billet formation and solidified skin thickness distribution along casting mold walls at different levels of liquid metal were investigated. The casting mold consisted of two rotating inclined walls in its upper part and two reciprocating vertical walls. The reduction of skin of casting proceeded in the upper part of mold. Based on the experimental results obtained the influence of metal level in a casting mold on billet formation is determined> The reduction degree needed for continuous process of casting and forging is also defined. The change in skin thickness with billet length under various crystallization conditions is established

  4. Simulation of Deformation Texture Evolution During Multi Axial Forging of Interstitial Free Steel

    Science.gov (United States)

    Gurao, N. P.; Kumar, P.; Sarkar, A.; Brokmeier, H.-G.; Suwas, Satyam

    2013-04-01

    Bulk texture measurement of multi-axial forged body center cubic interstitial free steel performed in this study using x-ray and neutron diffraction indicated the presence of a strong {101} single texture component. Viscoplastic self-consistent simulations could successfully predict the formation of this texture component by incorporating the complicated strain path followed during this process and assuming the activity of {101} slip system. In addition, a first-order estimate of mechanical properties in terms of highly anisotropic yield locus and Lankford parameter was also obtained from the simulations.

  5. Backward can extrusion with conical,rotating punch as a cold forging tribology test

    DEFF Research Database (Denmark)

    Ceron, Ermanno; Bay, Niels; Tetsuo, A.

    2011-01-01

    with an analysis of the sliding velocity distribution along the punch nose. The latter is determined by FE analysis of the test. Results show friction stress for unalloyed low C-steel provided with different types of lubricants, e.g. phosphate coating plus soap, phosphate coating plus MoS2 and single bathe...... lubrication with PULS. The new test is so severe, that it is possible to break down the best lubrication systems for cold forging, such as phosphate coating plus soap and MoS2....

  6. New lubricant systems for cold and warm forging – advantages and limitations

    DEFF Research Database (Denmark)

    Bay, Niels

    2011-01-01

    The increasing focus on environmental issues and the requirements to establish solutions diminishing the impact on working environment as well as external environment has strongly motivated the efforts to develop new, environmentally friendly tribological systems for metal forming production....... The present paper gives an overview of these efforts substituting environmentally hazardous lubricants in cold, warm and hot forging by new, more harmless lubricants. Introduction of these new lubricants, however, has some drawbacks due to lower limits of lubrication leading to risk of pick-up, poor product...

  7. Cell response to hydroxyapatite surface topography modulated by sintering temperature.

    Science.gov (United States)

    Mealy, Jacob; O'Kelly, Kevin

    2015-11-01

    Increased mesenchymal stem cell (MSC) activity on hydroxyapatite (HA) bone tissue engineering scaffolds will improve their viability in diffusion-based in vivo environments and is therefore highly desirable. This work focused on modulating the sintered HA surface topography with a view to increasing cell activity; this was achieved by varying the sintering temperature of the HA substrates. Cells were cultured on the substrates for periods of up to 19 days and displayed a huge variation in viability. MSC metabolic activity was measured using a resazurin sodium salt assay and revealed that surfaces sintered from 1250 to 1350°C significantly outperformed their lower temperature counterparts from day one (p ≤ 0.05). Surfaces sintered at 1300°C induced 57% more cell activity than the control at day 16. No significant activity was observed on surfaces sintered below 1200°C. It is suggested that this is due to the granular morphology produced at these temperatures providing insufficient contact area for cell attachment. In addition, we propose the average surface wavelength as a more quantitative surface descriptor than those readily found in the literature. The wavelengths of the substrates presented here were highly correlated with cell activity (R(2)  = 0.9019); with a wavelength of 2.675 µm on the 1300°C surface inducing the highest cell response. © 2015 Wiley Periodicals, Inc.

  8. Consolidation of metallic hollow spheres by electric sintering

    Science.gov (United States)

    Mironov, V.; Tatarinov, A.; Lapkovsky, V.

    2017-07-01

    This paper considers peculiarities of the technology of production of structures from metallic hollow spheres (MHS) using magnetic fields and electric sintering. In these studies, the raw material was MHS obtained by burning of polystyrene balls coated by carbon steel. MHS had an outer diameter of 3-5 mm and a steel wall thickness of 70-120 microns. Pulsed current generators were used for electric sintering of MHS to obtain different spatial structures. Since MHS have small strength, the compressive pressure during sintering should be minimal. To improve the adhesion strength and reduce the required energy for sintering, hollow spheres were coated with copper by ion-plasma sputtering in vacuum. The coating thickness was 10-15 microns. The ferromagnetic properties of MHS allowed using of magnet fields for orientation of the spheres in the structures, as well as using of perforated tapes acting as orienting magnetic cores. Ultrasonic testing of MHS structures has been tried using through propagation of ultrasound in low kilohertz frequency range. Sensitivity of the propagation parameters to water filling of inter-spheres space and sintering temperature was demonstrated.

  9. Leaching of metals from fresh and sintered red mud.

    Science.gov (United States)

    Ghosh, Indrani; Guha, Saumyen; Balasubramaniam, R; Kumar, A V Ramesh

    2011-01-30

    The disposal of red mud, a solid waste generated during the extraction of alumina from bauxite, is one of the major problems faced by the aluminum industry. Proper disposal followed by its utilization, for example as bricks, can provide a satisfactory solution to this problem. Pollution potential of red mud and its finished product, due to metals leaching out from them under certain environmental conditions, need to be studied. Sintering of red mud was performed in a resistance type vertical tube furnace to simulate the brick-making conditions in lab-scale. Leachability of metals in red mud and the sintered product was evaluated by performing sequential extraction experiments on both. The metals studied were the 'macro metals' iron and aluminum and the 'trace metals' copper and chromium. The total extractabilities of all the metals estimated by the microwave digestion of red mud samples decreased due to sintering. The leachability in sequential extraction of the macro metals iron and aluminum, on the other hand, increased due to sintering in all phases of sequential extraction. However, the effect of sintering on the leachability of the trace metals by sequential extraction was different for copper and chromium in different fractions of sequential extraction. Copyright © 2010 Elsevier B.V. All rights reserved.

  10. Low sintering temperature glass waste forms for sequestering radioactive iodine

    Science.gov (United States)

    Nenoff, Tina M.; Krumhansl, James L.; Garino, Terry J.; Ockwig, Nathan W.

    2012-09-11

    Materials and methods of making low-sintering-temperature glass waste forms that sequester radioactive iodine in a strong and durable structure. First, the iodine is captured by an adsorbant, which forms an iodine-loaded material, e.g., AgI, AgI-zeolite, AgI-mordenite, Ag-silica aerogel, ZnI.sub.2, CuI, or Bi.sub.5O.sub.7I. Next, particles of the iodine-loaded material are mixed with powdered frits of low-sintering-temperature glasses (comprising various oxides of Si, B, Bi, Pb, and Zn), and then sintered at a relatively low temperature, ranging from 425.degree. C. to 550.degree. C. The sintering converts the mixed powders into a solid block of a glassy waste form, having low iodine leaching rates. The vitrified glassy waste form can contain as much as 60 wt % AgI. A preferred glass, having a sintering temperature of 500.degree. C. (below the silver iodide sublimation temperature of 500.degree. C.) was identified that contains oxides of boron, bismuth, and zinc, while containing essentially no lead or silicon.

  11. [Influence on microstructure of dental zirconia ceramics prepared by two-step sintering].

    Science.gov (United States)

    Jian, Chao; Li, Ning; Wu, Zhikai; Teng, Jing; Yan, Jiazhen

    2013-10-01

    To investigate the microstructure of dental zirconia ceramics prepared by two-step sintering. Nanostructured zirconia powder was dry compacted, cold isostatic pressed, and pre-sintered. The pre-sintered discs were cut processed into samples. Conventional sintering, single-step sintering, and two-step sintering were carried out, and density and grain size of the samples were measured. Afterward, T1 and/or T2 of two-step sintering ranges were measured. Effects on microstructure of different routes, which consisted of two-step sintering and conventional sintering were discussed. The influence of T1 and/or T2 on density and grain size were analyzed as well. The range of T1 was between 1450 degrees C and 1550 degrees C, and the range of T2 was between 1250 degrees C and 1350 degrees C. Compared with conventional sintering, finer microstructure of higher density and smaller grain could be obtained by two-step sintering. Grain growth was dependent on T1, whereas density was not much related with T1. However, density was dependent on T2, and grain size was minimally influenced. Two-step sintering could ensure a sintering body with high density and small grain, which is good for optimizing the microstructure of dental zirconia ceramics.

  12. Granulation of coke breeze fine for using in the sintering process

    Directory of Open Access Journals (Sweden)

    Mohamed F.M.

    2010-01-01

    Full Text Available Coke breeze is the main fuel used in the sintering process. The value of -3+1 mm. represents the most favorable particle size for coke breeze in the sintering process. About 20% of total coke fines (-0.5 mm are produced during different steps of preparation. Introducing these fines during the sintering process proves to be very harmful for different operating parameters. Thus ,this study aims at investigating the production of granules resulting from these fines using molasses as organic binder and its application in sintering of an iron ore. The results showed that the granules having the highest mechanical properties were obtained with 14.5 wt % molasses addition. The sintering experiments were performed by using coke breeze in different shapes (-3+1 mm in size, coke breeze without sieving and coke breeze granules -3+1 mm. The reduction experiments, microscopic structure and X-ray analysis for the produced sinter were carried out. The results revealed that, all sinter properties (such as shatter test, productivity of sinter machine and blast furnace, reduction time and chemical composition for produced sinter by using coke breeze with size -3+1 mm and coke breeze granules were almost the same. The iron ore sinter which was produced by using coke breeze without sieving yielded low productivity for both sinter machine and blast furnace. Furthermore, using coke breeze without sieving in sintering of an iron ore decreases the vertical velocity of sinter machine and increases the reduction time.

  13. Tribological Investigations of Hard-Faced Layers and Base Materials of Forging Dies with Different Kinds of Lubricants Applied

    Directory of Open Access Journals (Sweden)

    V. Lazić

    2010-12-01

    Full Text Available This paper gives a procedure for choosing the right technology for reparative hard facing of damaged forging dies. Since they are subject to impact loads and cyclic temperature elevations, forging dies should be made of steel that is able to withstand great impact loads, maintain good mechanical properties at elevated temperatures and that is resistant to wear and thermal fatigue. For these reasons, forging dies are made of conditionally weldable alloy tool steels; however it makes hard facing of damaged tools even more difficult. In this paper, wear resistance of base materials, hard-faced layers and heat-affected zones are tribologically investigated when two different lubricants - pure synthetical oil LM 76 and LM 76 with 6% molybdenum disulfide (MoS2 are applied. Tribological investigations have shown that the wear resistance of the hard faced layers is considerably greater than the wear resistance of the base material. However, the base material has better properties concerning friction.

  14. Best possible heat treatment of steel SA 336 F22 for the production of forged shells with heavy walls

    International Nuclear Information System (INIS)

    Badeau, J.P.; Poitrault, I.S.; De Badereau, A.; Blondeau, R.P.

    1986-01-01

    The manufacturing of thick-wall components, such as shells, for petrochemical reactors normally requires the 2.25Cr-1Mo(SA 336 F22) steel. This paper deals with: 1. Experienced difficulties in producing thick-wall forgings up to a thickness of 500 mm with standard 2.25Cr-1Mo steel. 2. The solutions offered by Le Creusot Heavy Forge. The studies discussed are: (1) the effect of the structure; (2) the effect of the chemical composition on hardenability and temper embrittlement in steel making; and (3) the effect of austenitization conditions. Some examples concerning industrial forgings are presented, among them: 1. The manufacturing of shells for the petrochemical industry. 2. A thick-wall shell from a 146-metric ton hollow ingot

  15. High performance sinter-HIP for hard metals

    International Nuclear Information System (INIS)

    Hongxia Chen; Deming Zhang; Yang Li; Jingping Chen

    2001-01-01

    The horizontal sinter-HIP equipment with great charge capacity and high performance, developed and manufactured by Central Iron and Steel Research Institute(CISRI), is mainly used for sintering and condensation of hard metals. This equipment is characterized by large hot zone, high heating speed, good temperature uniformity and fast cooling system. The equipment can provide uniform hot zone with temperature difference less than 6 o C at 1500-1600 o C and 6-10 MPa by controlling temperature, pressure and circulation of gas precisely. Using large scale horizontal sinter-HIP equipment to produce hard matals have many advantages such as stable quality, high efficiency of production, high rate of finished products and low production cost, so this equipment is a good choice for manufacturer of hard metals. (author)

  16. Electric Field-Assisted Pressureless Sintering of Ceramic Protonic Conductors

    DEFF Research Database (Denmark)

    Muccillo, R.; Esposito, Vincenzo; Zanetti De Florio, Daniel

    2017-01-01

    -5 A the electric current pulse amplitude. The sintering experiments were carried out in ambient atmosphere with the pellets positioned inside a vertical dilatometer furnace with Pt-Ir electrodes connected either to a power supply for applying the electric field or to an impedance analyzer for collecting [-Z''(ω) x......Gadolinium, yttrium and samarium-doped barium cerate (BCGd, BCY and BCSm, respectively) polycrystalline green pellets were submitted to electric field-assisted pressureless sintering experiments isothermally in the temperature range 800-1200oC under 100-200 V cm-1 electric fields, limiting to 1...... of the electrical conductivity of flash sintered specimens. Joule heating is assumed to be the primary effect of the electric current pulse through the specimens. Improved grain-to-grain contact and the removal of depleted chemical species due to Joule heating at the space charge region are proposed, respectively...

  17. Modeling Macroscopic Shape Distortions during Sintering of Multi-layers

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye

    Ceramic multi-layered composites are being used as components in various technologies ranging from electronics to energy conversion devices. Thus, different architectures of multi-layers involving ceramic materials are often required to be produced by powder processing, followed by sintering...... the camber development during co-firing. The effect of extrinsic factors (e.g. gravity, thickness ratio and friction) on the shape evolution of bi-layers during co-firing has been studied using the developed model and experiments. Furthermore, a new analytical model describing stresses during sintering...... of tubular bi-layer structures has been developed by using the direct correspondence between elasticity and linear viscous problems. The finite element model developed in this study and sintering experiments of tubular bi-layer sample have been used to verify and validate the developed analytical model...

  18. CdS sintered films: growth and characteristics

    International Nuclear Information System (INIS)

    Sharma, Monika; Kumar, Sushil; Sharma, L.M.; Sharma, T.P.; Husain, M.

    2004-01-01

    Cadmium sulphide finds extensive applications in a variety of optoelectronic devices. CdS, with a band gap of 2.43 eV, is a suitable window material in heterojunction solar cells that employ CdTe, Cu 2 S or CuInSe 2 as an absorber. Polycrystalline films of CdS, thickness ∼15 μm, were grown onto chemically clean and optically plane glass substrates by sintering process. A 10 min sintering time and 500 deg. C sintering temperature were found to be optimum. As deposited films were characterized through optical, structural and electrical transport properties using optical reflection spectroscopy, X-ray diffractometry and I-V characteristics techniques

  19. Nano pores evolution in hydroxyapatite microsphere during spark plasma sintering

    Directory of Open Access Journals (Sweden)

    Lin C.

    2011-01-01

    Full Text Available Micron-spherical granules of hydroxyapatite (HAp nanoparticles were prepared by powder granulation methods. Through subsequent sintering, porous HAp microspheres with tailored pore and grain framework structures were obtained. Detailed microstructure investigation by SEM and TEM revealed the correlation of the pore structure and the necking strength with the sintering profiles that determine the coalescence features of the nanoparticles. The partially sintered porous HAp microspheres containing more than 50% porosity consisting of pores and grains both in nano-scale are active in inducing the precipitation of HAp in simulated body fluid. The nano-porous HAp microspheres with an extensive surface and interconnecting pores thus demonstrate the potential of stimulating the formation of collagen and bone and the integration with the newly formed bones during physiological bone remodeling.

  20. Immobilization of high-level wastes into sintered glass: 1

    International Nuclear Information System (INIS)

    Russo, D.O.; Messi de Bernasconi, N.; Audero, M.A.

    1987-01-01

    In order to immobilize the high-level radioactive wastes from fuel elements reprocessing, borosilicate glass was adopted. Sintering experiments are described with the variety VG 98/12 (SiO 2 , TiO 2 , Al 2 O 3 , B 2 O 3 , MgO, CaO and Na 2 O) (which does not present devitrification problems) mixed with simulated calcinated wastes. The hot pressing line (sintering under pressure) was explored in two variants 1: In can; 2: In graphite matrix with sintered pellet extraction. With scanning electron microscopy it is observed that the simulated wastes do not disolve in the vitreous matrix, but they remain dispersed in the same. The results obtained point out that the leaching velocities are independent from the density and from the matrix type employed, as well as from the fact that the wastes do no dissolve in the matrix. (M.E.L.) [es

  1. High efficiency particulate removal with sintered metal filters

    International Nuclear Information System (INIS)

    Kirstein, B.E.; Paplawsky, W.J.; Pence, D.T.; Hedahl, T.G.

    1981-01-01

    Because of their particle removal efficiencies and durability, sintered metal filters have been chosen for HEPA filter protection in the off-gas treatment system for the proposed Idaho National Engineering Laboratory Transuranic Waste Treatment Facility. Process evaluation of sintered metal filters indicated a lack of sufficient process design data to assume trouble-free operation. Subsequent pilot-scale testing was performed with fly ash as the test particulate. The test results showed that the sintered metal filters can have an efficiency greater than 0.9999999 for the specific test conditions used. Stable pressure drop characteristics were observed in pulsed and reversed flow blowback modes of operation. Over 4900 hours of operation were obtained with operating conditions ranging up to approximately 90 0 C and 24 volume percent water vapor in the gas stream

  2. Evaluation of dilatometric techniques for studies of sintering kinetics

    International Nuclear Information System (INIS)

    El-Sayed Ali, M.; Toft Soerensen, O.

    1985-04-01

    The kinetics of the initial sintering stage of CeO 2 is evaluated by three different techniques: constant heating rate dilatometry, constant shrinkage rate dilatometry and a new technique recently introduced by the authors called Stepwise Isothermal Dilatometry (SID). Comparative measurements with these techniques showed that too high activation energies were obtained with the two first techniques, both of which can be termed as nonisothermal, whereas activation energies comparable to those reported for cation diffusion in other fluorite oxides were obtained with the latter technique. Of the three techniques SID is thus considered to be the most accurate for studies of the sintering kinetics. In contrast to the two nonisothermal techniques SID has the further advantage that both the controlling mechanism and its activation energy can be determined in a single experiment. From the SID-measurement it was concluded that the initial sintering stage of CeO 2 is controlled by grain-boundary diffusion. (author)

  3. High efficiency particulate removal with sintered metal filters

    International Nuclear Information System (INIS)

    Kirstein, B.E.; Paplawsky, W.J.; Pence, D.T.; Hedahl, T.G.

    1981-01-01

    Because of their particle removal efficiencies and durability, sintered metal filters have been chosen for high efficiency particulate air (HEPA) filter protection in the off-gas treatment system for the proposed Idaho National Engineering Laboratory Transuranic Waste Treatment Facility. Process evaluation of sintered metal filters indicated a lack of sufficient process design data to ensure trouble-free operation. Subsequence pilot scale testing was performed with flyash as the test particulate. The test results showed that the sintered metal filters can have an efficiency greater than 0.9999999 for the specific test conditions used. Stable pressure drop characteristics were observed in pulsed and reversed flow blowback modes of operation. Over 4900 hours of operation were obtained with operating conditions ranging up to approximately 90 0 C and 24 vol % water vapor in the gas stream

  4. Reactive Sintering of Bimodal WC-Co Hardmetals

    Directory of Open Access Journals (Sweden)

    Marek Tarraste

    2015-09-01

    Full Text Available Bimodal WC-Co hardmetals were produced using novel technology - reactive sintering. Milled and activated tungsten and graphite powders were mixed with commercial coarse grained WC-Co powder and then sintered. The microstructure of produced materials was free of defects and consisted of evenly distributed coarse and fine tungsten carbide grains in cobalt binder. The microstructure, hardness and fracture toughness of reactive sintered bimodal WC-Co hardmetals is exhibited. Developed bimodal hardmetal has perspective for demanding wear applications for its increased combined hardness and toughness. Compared to coarse material there is only slight decrease in fracture toughness (K1c is 14.7 for coarse grained and 14.4 for bimodal, hardness is increased from 1290 to 1350 HV units.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7511

  5. Characterizations of Rapid Sintered Nanosilver Joint for Attaching Power Chips

    Directory of Open Access Journals (Sweden)

    Shuang-Tao Feng

    2016-07-01

    Full Text Available Sintering of nanosilver paste has been extensively studied as a lead-free die-attach solution for bonding semiconductor power chips, such as the power insulated gated bipolar transistor (IGBT. However, for the traditional method of bonding IGBT chips, an external pressure of a few MPa is reported necessary for the sintering time of ~1 h. In order to shorten the processing duration time, we developed a rapid way to sinter nanosilver paste for bonding IGBT chips in less than 5 min using pulsed current. In this way, we firstly dried as-printed paste at about 100 °C to get rid of many volatile solvents because they may result in defects or voids during the out-gassing from the paste. Then, the pre-dried paste was further heated by pulse current ranging from 1.2 kA to 2.4 kA for several seconds. The whole procedure was less than 3 min and did not require any gas protection. We could obtain robust sintered joint with shear strength of 30–35 MPa for bonding 1200-V, 25-A IGBT and superior thermal properties. Static and dynamic electrical performance of the as-bonded IGBT assemblies was also characterized to verify the feasibility of this rapid sintering method. The results indicate that the electrical performance is comparable or even partially better than that of commercial IGBT modules. The microstructure evolution of the rapid sintered joints was also studied by scanning electron microscopy (SEM. This work may benefit the wide usage of nanosilver paste for rapid bonding IGBT chips in the future.

  6. Selection of the optimal hard facing (HF technology of damaged forging dies based on cooling time t8/5

    Directory of Open Access Journals (Sweden)

    D. Arsić

    2016-01-01

    Full Text Available In exploitation, the forging dies are exposed to heating up to very high temperatures, variable loads: compressive, impact and shear. In this paper, the reparatory hard facing of the damaged forging dies is considered. The objective was to establish the optimal reparatory technology based on cooling time t8/5 . The verification of the adopted technology was done by investigation of the hard faced layers microstructure and measurements of hardness within the welded layers’ characteristic zones. Cooling time was determined theoretically, numerically and experimentally.

  7. Multi-objective optimization of swash plate forging process parameters for the die wear/service life improvement

    Science.gov (United States)

    Hu, X. F.; Wang, L. G.; Wu, H.; Liu, S. S.

    2017-12-01

    For the forging process of the swash plate, the author designed a kind of multi-index orthogonal experiment. Based on the Archard wear model, the influences of billet temperature, die temperature, forming speed, top die hardness and friction coefficient on forming load and die wear were numerically simulated by DEFORM software. Through the analysis of experimental results, the best forging process parameters were optimized and determined, which could effectively reduce the die wear and prolong the die service life. It is significant to increase the practical production of enterprise, especially to reduce the production cost and to promote enterprise profit.

  8. Forging And Milling Contribution On Residual Stresses For A Textured Biphasic Titanium Alloy

    International Nuclear Information System (INIS)

    Deleuze, C.; Fabre, A.; Barrallier, L.; Molinas, O.

    2011-01-01

    Ti-10V-2Fe-3Al is a biphasic titanium alloy (α+β) used in aeronautical applications for its mechanical properties, such as its yield strength of 1200 MPa and it weighs 40% less than steel. This alloy is particularly useful for vital parts with complex geometry, because of its high forging capability. In order to predict the capability for fatigue lifetime, the designers need to know the residual stresses. X-Ray diffraction is the main experimental technique used to determine residual stresses on the surface. In this case, stress levels are primarily influenced by the complex forging and milling process. On this alloy in particular, it may be difficult to characterize stress due to modification of the microstructure close to the surface. Results obtained by x-ray analysis depend on the correct definition of the shape of the diffraction peaks. The more precisely defined the position of the peak, the more accurately the stresses are evaluated. This paper presents a method to detect if residual stresses can be characterized by x-ray diffraction. The characterization of hardness seems to be a relevant technique to quickly analyze the capability of x-ray diffraction to determine residual stresses.

  9. Weld-forged rotors of the turbines for nuclear and thermal power plants

    International Nuclear Information System (INIS)

    Rudkovskij, A.F.; German, S.I.

    1979-01-01

    Considered is a principally new technology and equipment for assembling and welding superheavy rotors with mass up to 200 tons. Construction peculiarities and advantages of the application of weld-forged rotors are noted. The technology proposed permits to provide for a horizontal assembling, subsequent welding and quality control of rotors, one bench being used instead of three ones. The application of horizontal assembling and complex welding of rotors in one position permits not only to shorten the cycle of assembling and welding, too decrease the equipment costs and release production capacities, but also to improve substantially the quality of welds and especially the accuracy of rotor production. The equipment allows one to assemble and weld rotors with the mass up to 250 tons at maximum rotor diameter up to 2500 mm and length up to 13000 mm. Presented are data characterizing chemical composition and mechanical properties of steels used for forging of welded rotors. Also given are the results of studying mechanical properties of welded joints, welding and thermal treatment of which were made in accordance with the technology proposed. Serial production of rotors for turbines with the power of 500, 1000 and 1200 Mw is shown to be mastered along with the manufacture of welded rotors for cylinders of low, medium and high pressure turbines

  10. A Method For Producing Hollow Shafts By Rotary Compression Using A Specially Designed Forging Machine

    Directory of Open Access Journals (Sweden)

    Tomczak J.

    2015-09-01

    Full Text Available The paper presents a new method for manufacturing hollow shafts, where tubes are used as billet. First, the design of a specially designed forging machine for rotary compression is described. The machine is then numerically tested with regard to its strength, and the effect of elastic strains of the roll system on the quality of produced parts is determined. The machine’s strength is calculated by the finite element method using the NX Nastran program. Technological capabilities of the machine are determined, too. Next, the results of the modeling of the rotary compression process for a hollow stepped shafts by the finite element method are given. The process for manufacturing hollow shafts was modeled using the Simufact.Forming simulation program. The FEM results are then verified experimentally in the designed forging machine for rotary compression. The experimental results confirm that axisymmetric hollow shafts can be produced by the rotary compression method. It is also confirmed that numerical methods are suitable for investigating both machine design and metal forming processes.

  11. Standard method of macroetch testing steel bars, billets, blooms, and forgings

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2001-01-01

    1.1 Macroetching, which is the etching of specimens for macrostructural examination at low magnifications, is a frequently used technique for evaluating steel products such as bars, billets, blooms, and forgings. 1.2 Included in this method is a procedure for rating steel specimens by a graded series of photographs showing the incidence of certain conditions. The method is limited in application to bars, billets, blooms, and forgings of carbon and low alloy steels. 1.3 A number of different etching reagents may be used depending upon the type of examination to be made. Steels react differently to etching reagents because of variations in chemical composition, method of manufacture, heat treatment and many other variables. Establishment of general standards for acceptance or rejection for all conditions is impractical as some conditions must be considered relative to the part in which it occurs. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is ...

  12. Wavelet Analysis of Resultant Velocity Belonging to Genuine and Forged Signatures.

    Science.gov (United States)

    Syed Ahmad, Sharifah Mumtazah; Loo, Ling Yim; Wan Adnan, Wan Azizun; Md Anwar, Rina

    2017-03-01

    This study presents a wavelet analysis of resultant velocity features belonging to genuine and forged groups of signature sample. Signatures of individuals were initially classified based on visual human perceptions of their relative sizes, complexities, and legibilities of the genuine counterparts. Then, the resultant velocity was extracted and modeled through wavelet analysis from each sample. The wavelet signal was decomposed into several layers based on maximum overlap discrete wavelet transform (MODWT). Next, the zero crossing rate features were calculated from all the high wavelet sub-bands. A total of seven hypotheses were then tested using a two-way ANOVA testing methodology. Of these, four hypotheses were conducted to test for significance differences between distributions. In addition, three hypotheses were run to provide test for interaction between two factors of signature authentication versus perceived classification. The results demonstrated that both feature distributions belonging to genuine and forged groups of samples cannot be distinguished by themselves. Instead, they were significantly different under the influence of two other inherent factors, namely perceived size and legibility. Such new findings are useful information particularly in providing bases for forensic justifications in establishing the authenticity of handwritten signature specimens. © 2016 American Academy of Forensic Sciences.

  13. Brittle Fracture Behaviors of Large Die Holders Used in Hot Die Forging

    Directory of Open Access Journals (Sweden)

    Weifang Zhang

    2017-05-01

    Full Text Available Brittle fracture of large forging equipment usually leads to catastrophic consequences. To avoid this kind of accident, the brittle fracture behaviors of a large die holder were studied by simulating the practical application. The die holder is used on the large die forging press, and it is made of 55NiCrMoV7 hot-work tool steel. Detailed investigations including mechanical properties analysis, metallographic observation, fractography, transmission electron microscope (TEM analysis and selected area electron diffraction (SAED were conducted. The results reveal that the material generated a large quantity of large size polyhedral M23C6 (M: Fe and Cr mainly and elongated M3C (M: Fe mainly carbides along the martensitic lath boundaries when the die holder was recurrently tempered and water-cooled at 250 °C during the service. The large size carbides lead to the material embrittlement and impact toughness degradation, and further resulted in the brittle fracture of the die holder. Therefore, the operation specification must be emphasized to avoid the die holder being cooled by using water, which is aimed at accelerating the cooling.

  14. Electrical anisotropy in the hot-forged CaBi 4Ti 4O 15 ceramics

    Science.gov (United States)

    Rout, S. K.; Hussain, A.; Sinha, E.; Ahn, C. W.; Kim, I. W.

    2009-06-01

    Textured CaBi 4Ti 4O 15 (CBT) ceramics have been fabricated via a hot-forging technique. The effect of grain orientation on the dielectric and electrical properties is studied by impedance ( Z∗) and modulus ( M∗) spectroscopy. The degree of orientation ( F) calculated from X-ray diffraction pattern is found to be 89.4% along the c-axis of the crystal structure. The permittivity was measured along both perpendicular and parallel directions of the forging axis. The ratio of permittivity along perpendicular to parallel direction is found to be ˜3 at the Curie temperature of 797 °C. The non-superimposition of the normalized Z″ and M″ vs. frequency plot revealed the conduction in the material is localized and deviate from ideal Debye behavior. The power law exponent n of the material has been explained on the basis of jump relaxation model and revealed the conduction through grain boundary. Activation energy ( Ea) is obtained from Arrhenius plots of the dc conductivity for both the ceramics and it is found to be 0.89 eV and 0.78 eV for CBT (∥) and CBT (⊥), respectively.

  15. Deducing material quality in cast and hot-forged steels by new bending test

    Science.gov (United States)

    Valberg, Henry; Langøy, Morten; Nedreberg, Mette; Helvig, Torgeir

    2017-10-01

    A special bend test has been developed and applied for the purpose of characterization and comparison of the material ductility in crankpin steel discs manufactured by casting, or casting subsequently followed by hot open-die forging (ODF) or closed-die forging (CDF). The bending test specimen consists of a small rectangular plate of material with a round hole cut out in the middle. The "eye-shape" specimens were cut out from various positions either near to the surface of, or from the interior of the discs. The test method revealed differences in ductility for the investigated materials, and for different depth positions inside the discs. The roughening of the specimen surface on the top-side of the specimen bend also varied dependent on the processing method for the material. Current results show that this test method is useful for evaluation of material quality in differently processed material. Experimental bend test results are presented for differently processed variants of the same material, i.e., crankpin discs either made by solely casting or casting subsequently followed by hot working either by ODF or CDF.

  16. Study on microstructures in the steel for nuclear power large forgings under different cooling conditions

    International Nuclear Information System (INIS)

    Han Lizhan; Gu Jianfeng; Xu Jun; Pan Jiansheng; Long Zhinan

    2012-01-01

    The continuous cooling transformation (CCT) diagram has been investigated for the SA508 Gr.3 steel used as the large forgings of nuclear power using the thermal simulator Gleeble 3500, the microstructures obtained under different cooling rates and isothermal temperatures have also been observed carefully with the SEM and OM. The results show that the critical cooling rate of martensite is larger than 20 ℃/s, and that for bainite is about 1℃/s. The bad microstructures such as the granular bainite, and acicular ferrite form when the cooling rate less than 0.5℃/s. The medium harden ability of steel SA508 Gr.3 proposes very high requirement for heat treatment, and it is very difficult to get uniform microstructure and property throughout the whole section of a large forging for nuclear power. Thus, highly attention should be paid on the manufacture of nuclear power equipment and corresponding fundamental research in this aspect should be carried out intensively. (authors)

  17. On the quench sensitivity of 7010 aluminum alloy forgings in the overaged condition

    Energy Technology Data Exchange (ETDEWEB)

    Tiryakioğlu, Murat, E-mail: m.tiryakioglu@unf.edu [School of Engineering, University of North Florida, Jacksonville, FL 32224 (United States); Robinson, Jeremy S. [Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick (Ireland); Eason, Paul D. [School of Engineering, University of North Florida, Jacksonville, FL 32224 (United States)

    2014-11-17

    The quench sensitivity of an overaged 7010 alloy forging was characterized by tensile and Vickers hardness tests, as well as scanning electron microscopy. Longitudinal tensile specimens, excised from a rectilinear open die forging were cooled from the solution treatment temperature following thirty-two different cooling paths including interrupted and delayed quenches. SEM analysis of the microstructure showed that quench precipitates were (i) Al{sub 2}CuMg (S) which nucleated heterogeneously on grain boundaries and (ii) Mg(Zn,Cu,Al){sub 2} (η) on grain boundaries, dispersoid bands, subgrain boundaries as well as in the aluminum matrix. The quench sensitivity of the alloy's yield strength and Vickers hardness was modeled simultaneously by quadruple-C curves, using an improved methodology for Quench Factor Analysis. The four C-curves used in the model represented loss of solute by (i) precipitation of S on grain boundaries, and precipitation of η (ii) on grain boundaries and dispersoid bands, (iii) on subgrain boundaries and (iv) in the matrix. The model yielded coefficient of determination (R{sup 2}) values of 0.967 and 0.974 for yield strength and Vickers hardness, respectively. The model and the implications of the results are discussed in this paper.

  18. Preparation of Ni-Ti shape memory alloy by spark plasma sintering method

    Czech Academy of Sciences Publication Activity Database

    Salvetr, P.; Kubatík, Tomáš František; Novák, P.

    2016-01-01

    Roč. 16, č. 4 (2016), s. 804-808 ISSN 1213-2489 Institutional support: RVO:61389021 Keywords : Ni-Ti alloy * Powder metallurgy * Reactive sintering * Spark plasma sintering Subject RIV: JK - Corrosion ; Surface Treatment of Materials

  19. Pressure sintering and creep deformation: a joint modeling approach

    International Nuclear Information System (INIS)

    Notis, M.R.

    1979-10-01

    Work related to microchemical and microstructural aspects of the joint modeling of pressure sintering and creep in ceramic oxides is reported. Quantitative techniques for the microchemical analysis of ceramic oxides and for the examination of impurity segregation effects in polycrystalline ceramic materials were developed. This has included fundamental absorption corrections for the oxygen anion species as a function of foil thickness. The evolution in microstructure during the transition from intermediate stage to final stage densification during hot pressing of cobalt oxide and preliminary studies with doped oxides were studied. This work shows promise in using time-integrated microstructural effects to elucidate the role of impurities in the sintering of ceramic materials

  20. In situ Transmission Electron Microscopy of catalyst sintering

    DEFF Research Database (Denmark)

    DeLaRiva, Andrew T.; Hansen, Thomas Willum; Challa, Sivakumar R.

    2013-01-01

    Recent advancements in the field of electron microscopy, such as aberration correctors, have now been integrated into Environmental Transmission Electron Microscopes (TEMs), making it possible to study the behavior of supported metal catalysts under operating conditions at atomic resolution. Here......, we focus on in situ electron microscopy studies of catalysts that shed light on the mechanistic aspects of catalyst sintering. Catalyst sintering is an important mechanism for activity loss, especially for catalysts that operate at elevated temperatures. Literature from the past decade is reviewed...

  1. Pressure sintering and creep deformation: a joint modeling approach

    Energy Technology Data Exchange (ETDEWEB)

    Notis, M.R.

    1979-10-01

    Work related to microchemical and microstructural aspects of the joint modeling of pressure sintering and creep in ceramic oxides is reported. Quantitative techniques for the microchemical analysis of ceramic oxides and for the examination of impurity segregation effects in polycrystalline ceramic materials were developed. This has included fundamental absorption corrections for the oxygen anion species as a function of foil thickness. The evolution in microstructure during the transition from intermediate stage to final stage densification during hot pressing of cobalt oxide and preliminary studies with doped oxides were studied. This work shows promise in using time-integrated microstructural effects to elucidate the role of impurities in the sintering of ceramic materials.

  2. Method and apparatus for radio frequency ceramic sintering

    Science.gov (United States)

    Hoffman, Daniel J.; Kimrey, Jr., Harold D.

    1993-01-01

    Radio frequency energy is used to sinter ceramic materials. A coaxial waveguide resonator produces a TEM mode wave which generates a high field capacitive region in which a sample of the ceramic material is located. Frequency of the power source is kept in the range of radio frequency, and preferably between 60-80 MHz. An alternative embodiment provides a tunable radio frequency circuit which includes a series input capacitor and a parallel capacitor, with the sintered ceramic connected by an inductive lead. This arrangement permits matching of impedance over a wide range of dielectric constants, ceramic volumes, and loss tangents.

  3. Sintering of Kernel UO2 for High Temperature Reactor Fuel

    International Nuclear Information System (INIS)

    Sukarsono; Dwi-Heru-Sucahyo; Hidayati; Evi-Hertiviana; Bambang-Sugeng

    2000-01-01

    Sintering investigation of UO 2 gel has been done. The gel was preparedthrough two ways. The first, gel was produced using PVA as additive agent.The second gel was produced using HMTA and Urea as additive agent. From thepreparation of gel, the PVA method better than the urea - HMTA method,because was not necessary the cold temperature for sol preparation and alsowas not necessary the hot temperature for gelation process. After nextprocessing, the sintered gel of gel through PVA, also better than HMTAprocess. (author)

  4. Sintering and microstructure of ZnO varistor

    International Nuclear Information System (INIS)

    Leite, E.R.; Longo, E.; Varela, J.A.

    1987-01-01

    The sintering and microstructure of ZnO-Bi 2 O 3 (ZB) and ZuO-Sb 2 O 3 -CoO-Bi 2 O 3 (ZSCB) varistors in several temperatures, for one hour in dry air temperature were studied. The compounds were analyzed by scanning electron microscopy, X-ray diffraction, differential thermal analysis and the density and porosity were determined by mercury picnometry. The experimental results showed that the ZB and ZSCB system sinters by liquid means and that liquid will control the density and grain growth mechanisms. (E.G.) [pt

  5. Forging Ahead

    Science.gov (United States)

    Finkel, Ed

    2017-01-01

    Community colleges always have played an integral role in training workers for infrastructure- and transportation-related fields like truck driving, construction, welding and electrical work. If the $1 trillion infrastructure package proposed by President Donald Trump comes to pass, these fields will grow significantly, at least for a while, which…

  6. Determination of optimum thermal debinding and sintering process parameters using Taguchi Method

    CSIR Research Space (South Africa)

    Seerane, M

    2015-07-01

    Full Text Available on the basis of obtaining a defect-free part after sintering and also determining a sintering time that gives high sintering density. Thermal debinding was conducted after solvent debinding. The feedstock used to produce green compacts composed of Ti6Al4V... International Light Metals Technology Conference (LMT 2015), Port Elizabeth, South Africa, July 27-29 Determination of Optimum Process for Thermal Debinding and Sintering using Taguchi Method SEERANE Mandya,*, CHIKWANDA Hildab, MACHAKA Ronaldc CSIR...

  7. Model for the evaluation and prediction of production rate of sinter ...

    African Journals Online (AJOL)

    A model has been derived for evaluation and prediction of production rate of sinter machine operating on vertical mode. The quadratic model expressed as: P = 0.4395 V – 0.0526 V2 + 0.54, showed that the production rate of the sinter machine was dependent on the vertical sintering height. The maximum deviation of the ...

  8. Influence of various manufacturing parameters on some characteristics of UO2 powders and their sintering behaviour

    International Nuclear Information System (INIS)

    Mintz, M.H.; Vaknin, Sh.; Kremener, A.; Hadari, Z.

    1977-02-01

    Various parameters in the process of manufacturing uranium dioxide are examined and their influence on the characteristics and sintering behaviour of the powders obtained established. In addition some correlations between the powder aggregates microstructure and their adhesion properties and sintering behaviour are indicated. Shrinkage during the sintering process is also discussed

  9. Application of fine-grained coke breeze fractions in the process of iron ore sintering

    Directory of Open Access Journals (Sweden)

    M. Niesler

    2014-01-01

    Full Text Available The testing cycle, described in the paper, included fine-grained coke breeze granulation tests and iron concentrate sintering tests with the use of selected granulate samples. The use of granulated coke breeze in the sintering process results in a higher process efficiency, shorter sintering duration and fuel saving.

  10. Sintering of uranium dioxide pellets (UO2) in an oxidizing atmosphere (C O2)

    International Nuclear Information System (INIS)

    Santos, G.R.T.

    1992-01-01

    This work consists in the study of the sintering process of U O 2 pellets in an oxidizing atmosphere. Sintering tests were performed in an CO 2 atmosphere and the influence of temperature and time on the pellets density and microstructure were verified. The results obtained were compared to those from the conventional sintering process and its efficiency was confirmed. (author)

  11. Fabrication of High Strength and Ductile Stainless Steel Fiber Felts by Sintering

    Science.gov (United States)

    Wang, J. Z.; Tang, H. P.; Qian, M.; Li, A. J.; Ma, J.; Xu, Z. G.; Li, C. L.; Liu, Y.; Wang, Y.

    2016-03-01

    Stainless steel fiber felts are important porous stainless steel products for a variety of industry applications. A systematic study of the sintering of 28- µm stainless steel fibers has been conducted for the first time, assisted with synchrotron radiation experiments to understand the evolution of the sintered joints. The critical sintering conditions for the formation of bamboo-like grain structures in the fiber ligaments were identified. The evolution of the number density of the sintered joints and the average sintered neck radius during sintering was assessed based on synchrotron radiation experiments. The optimum sintering condition for the fabrication of high strength and ductile 28- µm-diameter stainless steel fiber felts was determined to be sintering at 1000°C for 900 s. Sintering under this optimum condition increased the tensile strength of the as-sintered stainless steel fiber felts by 50% compared to conventional sintering (1200°C for 7200 s), in addition to much reduced sintering cycle and energy consumption.

  12. Spark Plasma Sintered AlN-BN Composites and Its Thermal Conductivity

    NARCIS (Netherlands)

    Zhao Haiyang, [No Value; Wang Weimin, [No Value; Wang Hao, [No Value; Fu Zhengyi, [No Value

    2008-01-01

    A series of samples of hexagonal boron nitride-aluminum nitride ceramic composites with different amounts of CaF(2) as sintering aid were prepared by spark plasma sintered at 1700-1850 degrees C for 5 min. The addition of CaF(2) effectively lowered the sintering temperature and promoted the

  13. Process for the production of metal nitride sintered bodies and resultant silicon nitride and aluminum nitride sintered bodies

    Science.gov (United States)

    Yajima, S.; Omori, M.; Hayashi, J.; Kayano, H.; Hamano, M.

    1983-01-01

    A process for the manufacture of metal nitride sintered bodies, in particular, a process in which a mixture of metal nitrite powders is shaped and heated together with a binding agent is described. Of the metal nitrides Si3N4 and AIN were used especially frequently because of their excellent properties at high temperatures. The goal is to produce a process for metal nitride sintered bodies with high strength, high corrosion resistance, thermal shock resistance, thermal shock resistance, and avoidance of previously known faults.

  14. Effects of sintering temperature on the density and porosity

    African Journals Online (AJOL)

    2013-03-01

    Mar 1, 2013 ... used as a model system for the investigation of ce- ramic sintering behavior [1, 2]. However, the system ... cially available metal foams are based on aluminium, copper, nickel and metal alloys [4]. ... Zhao et al [9] reported that the porosity of the as- manufactured foam is determined by the density of.

  15. Effect of sintering temperature and heating mode on consolidation of ...

    Indian Academy of Sciences (India)

    ventional vacuum furnace (10. −2 torr). The transverse rupture strength (TRS) samples (31·7 ... testing machine (model: 1195, INSTRON, UK) at a cross- head speed of 0·5 mm/min and SEM of fractured surfaces ... Photographs of 7775 alloy sintered under vacuum at. 590. ◦. C and 630. ◦. C in conventional furnace. where f is ...

  16. Novel sintered ceramic materials incorporated with EAF carbon steel slag

    Science.gov (United States)

    Karayannis, V.; Ntampegliotis, K.; Lamprakopoulos, S.; Papapolymerou, G.; Spiliotis, X.

    2017-01-01

    In the present research, novel sintered clay-based ceramic materials containing electric arc furnace carbon steel slag (EAFC) as a useful admixture were developed and characterized. The environmentally safe management of steel industry waste by-products and their valorization as secondary resources into value-added materials towards circular economy have attracted much attention in the last years. EAF Carbon steel slag in particular, is generated during the manufacture of carbon steel. It is a solid residue mainly composed of rich-in- Fe, Ca and Si compounds. The experimental results show that the beneficial incorporation of lower percentages of EAFC up to 6%wt. into ceramics sintered at 950 °C is attained without significant variations in sintering behavior and physico-mechanical properties. Further heating up to 1100 °C strongly enhances the densification of the ceramic microstructures, thus reducing the porosity and strengthening their mechanical performance. On the other side, in terms of thermal insulation behavior as well as energy consumption savings and production cost alleviation, the optimum sintering temperature appears to be 950 °C.

  17. Effect of sintering temperature and time on the mechanical ...

    Indian Academy of Sciences (India)

    Administrator

    partial sintering of the alloy particles on the cell walls. Pore size and pore interconnectivity are critical factors in porous material for tissue engineering. Micropores are scale to provide pathways for body fluid and nutrient transpor- tation, needed for bone regeneration and growth.25 In addition, these kinds of pores provide ...

  18. Diffusion of silver during sintering in high permittivity COG dielectrics

    NARCIS (Netherlands)

    Mikkenie, R.; Groen, W.A.; Drift, R. van der

    2010-01-01

    To achieve cost reduction in multi-layer ceramic capacitors and actuators, which use a silver-palladium alloy as internal electrode, the trend is to use alloys with the highest silver content possible. This requires ceramic materials which must be sintered at a relative low temperature. Goal is to

  19. Sintering, camber development of layer composites and a new ...

    Indian Academy of Sciences (India)

    Abstract. Zinc–magnesium titanate dielectrics/nickel–zinc–copper ferrite layer composites were prepared by tape- casting technique combined with a uniaxial pressure shaping technique. The sintering and camber development of the composites were investigated. The results show that the difference of shrinkage in the ...

  20. Electrical discharge machining studies on reactive sintered FeAl

    Indian Academy of Sciences (India)

    Electrical discharge machining (EDM) studies on reactive sintered FeAl were carried out with different process parameters. The metal removal rate and tool removal rate were found to increase with the applied pulse on-time. The surface roughness of machined surface also changed with the applied pulse on-time.