Microstructural Quantification of Rapidly Solidified Undercooled D2 Tool Steel

Science.gov (United States)

Valloton, J.; Herlach, D. M.; Henein, H.; Sediako, D.

2017-10-01

Rapid solidification of D2 tool steel is investigated experimentally using electromagnetic levitation (EML) under terrestrial and reduced gravity conditions and impulse atomization (IA), a drop tube type of apparatus. IA produces powders 300 to 1400 μm in size. This allows the investigation of a large range of cooling rates ( 100 to 10,000 K/s) with a single experiment. On the other hand, EML allows direct measurements of the thermal history, including primary and eutectic nucleation undercoolings, for samples 6 to 7 mm in diameter. The final microstructures at room temperature consist of retained supersaturated austenite surrounded by eutectic of austenite and M7C3 carbides. Rapid solidification effectively suppresses the formation of ferrite in IA, while a small amount of ferrite is detected in EML samples. High primary phase undercoolings and high cooling rates tend to refine the microstructure, which results in a better dispersion of the eutectic carbides. Evaluation of the cell spacing in EML and IA samples shows that the scale of the final microstructure is mainly governed by coarsening. Electron backscattered diffraction (EBSD) analysis of IA samples reveals that IA powders are polycrystalline, regardless of the solidification conditions. EBSD on EML samples reveals strong differences between the microstructure of droplets solidified on the ground and in microgravity conditions. While the former ones are polycrystalline with many different grains, the EML sample solidified in microgravity shows a strong texture with few much larger grains having twinning relationships. This indicates that fluid flow has a strong influence on grain refinement in this system.

Fabrication and tensile properties of rapidly solidified Cu-10wt. %Ni alloy. [Cu-10Ni

Energy Technology Data Exchange (ETDEWEB)

Baril, D; Angers, R; Baril, J [Dept. of Mining and Metallurgy, Laval Univ., Ste-Foy, Quebec (Canada)

1992-10-15

Cu-10wt.%Ni ribbons were produced by melt spinning and cut into small particles with a blade cutter mill. The powders were then hot consolidated to full density by hot pressing followed by hot extrusion. Tensile properties of the resulting pieces were measured. Cu-10wt.%Ni cast ingots were also hot extruded and mechanically tested to compare with the rapidly solidified alloy and to evaluate the possible benefits brought by the rapid solidification process.

Layered Composite of TiC-TiB2 to Ti-6Al-4V in Graded Composition by Combustion Synthesis in High-gravity Field

International Nuclear Information System (INIS)

Huang Xuegang; Zhao Zhongmin; Zhang Long

2013-01-01

By taking combustion synthesis to prepare solidified TiB 2 matrix ceramic in high-gravity field, the layered composite of TiC-TiB 2 ceramic to Ti-6Al-4V substrate in graded composition was achieved. XRD, FESEM and EDS results showed that the bulk full-density solidified TiC-TiB 2 composite was composed of fine TiB 2 platelets, TiC irregular grains, a few of α-Al 2 O 3 inclusions and Cr alloy phases, and α'-Ti phases alternating with Ti-enriched carbides constituted the matrix of the joint in which fine TiB platelets were embedded, whereas some C, B atoms were also detected at the heat-affected zone of Ti-6A1-4V substrate. The layered composite of the solidified ceramic to Ti-6Al-4V substrate in graded composition with continuous microstructure was considered a result of fused joint and inter-diffusion between liquid ceramic and surface-molten Ti alloy, followed by TiB 2 -Ti peritectic reaction and subsequent eutectic reaction in TiC-TiB-Ti ternary system.

Phase composition of rapidly solidified Ag-Sn-Cu dental alloys

International Nuclear Information System (INIS)

Lecong Dzuong; Do Minh Nghiep; Nguyen van Dzan; Cao the Ha

1996-01-01

The phase composition of some rapidly solidified Ag-Sn-Cu dental alloys with different copper contents (6.22 wtpct) has been studied by XRD, EMPA and optical microscopy. The samples were prepared from melt-spun ribbons. The microstructure of the as-quenched ribbons was microcrystalline and consisted of the Ag sub 3 Sn, Ag sub 4 Sn, Cu sub 3 Sn and Cu sub 3 Sn sub 8 phases. Mixing with mercury (amalgamation) led to formation of the Ag sub 2 Hg sub 3, Sn sub 7 Hg and Cu sub 6 Sn sub 5 phases. The amount of copper atoms in the alloys played an important role in phase formation in the amalgams

TEM Characterization and Properties of Cu-1 wt.% TiB2 Nanocomposite Prepared by Rapid Solidification and Subsequent Heat Treatment

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M. Sobhani

2012-12-01

Full Text Available Copper matrix composite reinforced by 1wt.% TiB2 particles was prepared using in situ reaction of Cu-1.4wt.% Ti and Cu-0.7wt.% B by rapid solidification and subsequent heat treatment for 1-20 hrs at 900ºC. High-resolution transmission electron microscopy (HRTEM characterization showed that primary TiB2 particles were formed in liquid copper. Heat treatment of as-solidified samples led to the formation of secondary TiB2 particles via spinodal decomposition of titanium-rich zone inside the grains. Mechanical properties (after 50% reduction in area as well as electrical conductivity of composite were evaluated after heat treatment and were compared with those of pure copper. The results indicated that, due to the formation of secondary TiB2 particles in the matrix, electrical conductivity increased along with hardness up to 10 hrs of heat treatment and reached 65% IACS and 155 HV, respectively. Moreover, the maximum ultimate (i.e. 580 MPa and yield (i.e. 555 MPa strengths of composite were achieved at this time.

Structure and mechanical properties of Al-3Fe rapidly solidified alloy

International Nuclear Information System (INIS)

Karakoese, Ercan; Keskin, Mustafa

2011-01-01

The Al based Al-3 wt%Fe alloy was prepared by conventionally casting (ingot) and further processed the melt-spinning technique and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) together with energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC) and the Vickers microhardness tester. The rapidly solidified (RS) binary alloys were composed of supersaturated α-Al solid solution and finely dispersed intermetallic phases. Experimental results showed that the mechanical properties of RS alloys were enhanced, which can be attributed to significant changes in the microstructure. The dependence of microhardness H V on the solidification rate (V) was analysed. These results showed that with the increasing values of V, the values of H V increased.

Formation of metastable phases and nanocomposite structures in rapidly solidified Al-Fe alloys

International Nuclear Information System (INIS)

Nayak, S.S.; Chang, H.J.; Kim, D.H.; Pabi, S.K.; Murty, B.S.

2011-01-01

Highlights: → Structures of nanocomposites in rapidly solidified Al-Fe alloys were investigated. → Nanoquasicrystalline, amorphous and intermetallics phases coexist with α-Al. → Nanoquasicrystalline phase was observed for the first time in the dilute Al alloys. → Thermodynamic driving force plays dominant role in precipitation of Fe-rich phases. → High hardness (3.57 GPa) was observed for nanocomposite of Al-10Fe alloy. - Abstract: In the present work the structure and morphology of the phases of nanocomposites formed in rapidly solidified Al-Fe alloys were investigated in details using analytical transmission electron microscopy and X-ray diffraction. Nanoquasicrystalline phases, amorphous phase and intermetallics like Al 5 Fe 2 , Al 13 F 4 coexisted with α-Al in nanocomposites of the melt spun alloys. It was seen that the Fe supersaturation in α-Al diminished with the increase in Fe content and wheel speed indicating the dominant role of the thermodynamic driving force in the precipitation of Fe-rich phases. Nanoquasicrystalline phases were observed for the first time in the dilute Al alloys like Al-2.5Fe and Al-5Fe as confirmed by high resolution TEM. High hardness (3.57 GPa) was measured in nanocomposite of Al-10Fe alloy, which was attributed to synergistic effect of solid solution strengthening due to high solute content (9.17 at.% Fe), dispersion strengthening by high volume fraction of nanoquasicrystalline phase; and Hall-Petch strengthening from finer cell size (20-30 nm) of α-Al matrix.

A study on crystalline phases present in the as-solidified and crystallized microstructures in Zr53Cu21Al10Ni8Ti8 alloy

International Nuclear Information System (INIS)

Neogy, S.; Tewari, R.; Srivastava, D.; Dey, G.K.

2011-01-01

In the present study the as-solidified and crystallized microstructures of Zr 53 Cu 21 Al 10 Ni 8 Ti 8 alloy have been examined in detail. Solidification was carried out by melt spinning, suction casting and copper mould casting techniques. The last technique yielded a partially crystalline microstructure, whereas, the other two techniques resulted in amorphous microstructures. (author)

Morphological evolution of primary TiC carbide in laser clad TiC reinforced FeAl intermetallic composite coating

Institute of Scientific and Technical Information of China (English)

陈瑶; 王华明

2003-01-01

The novel rapidly solidified TiC/FeAl composite coatings were fabricated by laser cladding on the substrate of 1Cr18Ni9Ti stainless steel, particular emphasis has been placed on the growth morphologies of TiC carbide and its growth mechanism under a constant solidification conditions. Results show that the growth morphology of TiC carbide strongly depends upon the nucleation process and mass transportation process of TiC forming elements in laser melt pool. With increasing amount of titanium and carbon in melt pool, the growth morphology of TiC carbide changes from block-like to star-like and well-developed dendrite. As the amount of titanium and carbon increases further, TiC carbide particles are found to be irregular polyhedral block. Although the growth morphologies of TiC are various,their advancing fronts are all faceted, illustrating that TiC carbide grows by the mechanism of lateral ledge growth.

Structural investigations of mechanical properties of Al based rapidly solidified alloys

International Nuclear Information System (INIS)

Karakoese, Ercan; Keskin, Mustafa

2011-01-01

Highlights: → Rapid solidification processing (RSP) involves exceptionally high cooling rates. → We correlate the microstructure of the intermetallic Al 3 Fe, Al 2 Cu and Al 3 Ni phases with the cooling rate. → The solidification rate is high enough to retain most of alloying elements in the Al matrix. → The rapid solidification has effect on the phase constitution. -- Abstract: In this study, Al based Al-3 wt.%Fe, Al-3 wt.%Cu and Al-3 wt.%Ni alloys were prepared by conventional casting. They were further processed using the melt-spinning technique and characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM) together with energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), differential scanning calorimetry (DSC) and the Vickers microhardness tester. The rapidly solidified (RS) binary alloys were composed of supersaturated α-Al solid solution and finely dispersed intermetallic phases. Experimental results showed that the mechanical properties of RS alloys were enhanced, which can be attributed to significant changes in the microstructure. RS samples were measured using a microhardness test device. The dependence of microhardness H V on the solidification rate (V) was analysed. These results showed that with the increasing values of V, the values of H V increased. The enthalpies of fusion for the same alloys were determined by DSC.

Evolution of the microstructure and nanohardness of Ti-48 at.%Al alloy solidified under high pressure

International Nuclear Information System (INIS)

Wang, Hongwei; Zhu, Dongdong; Zou, Chunming; Wei, Zunjie

2012-01-01

Highlights: → The microstructure of Ti-48Al alloy changes under high pressure. → With increasing pressure, the amount of γ s phase decreases. → High pressure leads to the decreasing of lamellar spacing. → The nanohardness of lamellar structure increases with pressure. -- Abstract: In this work the microstructure and nanohardness of Ti-48 at.%Al alloy solidified under different pressures (normal pressure, 2 GPa, 4 GPa) were experimental investigated by using a tungsten-carbide six-anvil apparatus. The results indicate that high pressure does not change the phase constitution of Ti-48 at.%Al alloy. However, the microstructure changes under high pressure. With increasing pressure, the volume fraction of interdendritic γ (γ s ) phase decreases and Al concentration in lamellae increases. When the pressure is 4 GPa, there is only a little γ s embedded in lamellar structure. The volume fraction of γ s phase is approximately 17.0% for normal pressure, 8.73% for 2 GPa, 0.69% for 4 GPa. The lamellar spacings also decrease with pressure, which are 495 nm, 345 nm, 227 nm under normal pressure, 2 GPa, 4 GPa, respectively. The change in nanohardness was discussed based on the microstructural observations. It shows a certain increase of the nanohardness as the pressure increases from normal pressure to 4 GPa. When the pressure is 4 GPa, the nanohardness increases by 50.2% compared with that of normal pressure.

Formation of an 18R long-period stacking ordered structure in rapidly solidified Mg88Y8Zn4 alloy

International Nuclear Information System (INIS)

Garcés, Gerardo; Requena, Guillermo; Tolnai, Domonkos; Pérez, Pablo; Medina, Judit; Stark, Andreas; Schell, Norbert; Adeva, Paloma

2016-01-01

The formation of the long-period stacking ordered structure (LPSO) in a Mg 88 Y 8 Zn 4 (at%) ribbon produced by melt spinning was studied using high energy X-ray synchrotron radiation diffraction during in-situ isochronal heating and transmission electron microscopy. The microstructure of the rapidly solidified ribbons is characterised by fine magnesium grains with yttrium and zinc in solid solution and primary 18R LPSO-phase segregated at grain boundaries. Using differential scanning calorimetry, a strong exothermal peak was observed around 300 °C which was associated with the development of the 18R-type LPSO-phase in the magnesium grains. The apparent activation energy calculated using the Kissinger model was 125 KJmol −1 and it is related to simultaneous diffusion of Y and Zn through magnesium basal plane. - Highlights: •The formation of the LPSO phase in rapidly solidified ribbons was studied. •The formation of the 18R LPSO starts at around 300 °C. •LPSO formation have to steps: Stacking faults along basal plane and then growth of 18R structure along the c direction.

Influence of micro-additions of bismuth on structures, mechanical and electrical transport properties of rapidly solidified Sn-3.5% Ag Alloy from melt

International Nuclear Information System (INIS)

El Bahay, M.M.; Mady, H.A.

2005-01-01

The present study was undertaken to investigate the influence of the Bi addition in the Sn-3.5 Ag rapidly solidified binary system for use as a Pb-free solder. The resulting properties of the binary system were extended to the Sn based ternary systems Sn 9 6.5-X Ag 3 .5 Bi x (0≤ X ≤ 2.5) solder. The structure and electrical resistivity of rapidly solidified (melt spun) alloys have been investigated. With the addition of up to 2.5 mass % Bi, the melting temperature decreases from 221.1 to 214.8 degree C. Wetting contact angle of the six alloys on Cu Zn 3 0 substrate are carried out at 573 K. Microhardness evaluations were also performed on the Sn-Ag-Bi alloys. The measured values and other researcher's results were compared with the calculated data

Numerical Research on Magnetic Field, Temperature Field and Flow Field During Melting and Directionally Solidifying TiAl Alloys by Electromagnetic Cold Crucible

Science.gov (United States)

Chen, Ruirun; Yang, Yaohua; Gong, Xue; Guo, Jingjie; Su, Yanqing; Ding, Hongsheng; Fu, Hengzhi

2017-12-01

The electromagnetic cold crucible (EMCC) technique is an effective method to melt and directionally solidify reactive and high-temperature materials without contamination. The temperature field and fluid flow induced by the electromagnetic field are very important for melting and controlling the microstructure. In this article, a 3D EMCC model for calculating the magnetic field in the charges (TiAl alloys) using the T-Ω finite element method was established and verified. Magnetic fields in the charge under different electrical parameters, positions and dimensions of the charge were calculated and analyzed. The calculated results show that the magnetic field concentrates in the skin layer, and the magnetic flux density ( B) increases with increasing of the frequency, charge diameter and current. The maximum B in the charge is affected by the position of the charge in EMCC ( h 1) and the charge height ( h 2), which emerges at the middle of coils ( h c) when the relationship of h c < h 1 + h 2 < h c + δ is satisfied. Lower frequency and smaller charge diameter can improve the uniformity of the magnetic field in the charge. Consequently, the induced uniform electromagnetic stirring weakens the turbulence and improves temperature uniformity in the vicinity of the solid/liquid (S/L) interface, which is beneficial to forming a planar S/L interface during directional solidification. Based on the above conclusions, the TiAlNb alloy was successfully melted with lower power consumption and directionally solidified by the square EMCC.

Characterization of the Ni-45wt% Ti shape memory alloy rapidly solidified

International Nuclear Information System (INIS)

Anselmo, G.C.S.; Castro, W.B. de; Araujo, C.J. de

2010-01-01

One important challenge of microsystems design is the implementation of miniaturized actuation principles efficient at the micro-scale. Shape memory alloys (SMAs) have early on been considered as a potential solution to this problem as these materials offer attractive properties like a high-power to weight ratio, large deformation and the capability to be processed at the micro-scale. shape memory characteristics of Ni-45wt%Ti alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray. In these experiments particular attention has been paid to change the velocity of cooling wheel from 30 to 50 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate on martensitic transformation behaviors and structure are discussed. (author)

Effect of titanium on structure and martensitic transformation in rapidly solidified Cu-Al-Ni-Mn-Ti alloys

International Nuclear Information System (INIS)

Dutkiewicz, J.; Czeppe, T.; Morgiel, J.

1999-01-01

Alloys of composition Cu-(11.8-13.5)%Al-(3.2-4)%Ni-(2-3)%Mn and 0-1%Ti (wt.%) were cast using the melt spinning method in He atmosphere. Ribbons obtained in this process showed grains from 0.5 to 30 μm depending on the type of alloy and wheel speed. Bulk alloys and most of the ribbons contained mixed 18R and 2H type martensite at room temperature (RT). Some ribbons, crystallizing at the highest cooling rate, retained also β phase due to a drop of M s below RT. The M s temperatures in ribbons were strongly lowered with increasing wheel speed controlling the solidification rate. This drop of M s shows a linear relationship with d -1/2 , where d is grain size. The strongest decrease of M s and smallest grains were found in the ribbons containing titanium due to its grain refinement effect. The cubic Ti rich precipitates, present in both Cu-Al-Ni-Ti and Cu-Al-Ni-Mn-Ti bulk, were dispersed in ribbons cast with intermediate cooling rates of up to 26 m s -1 , but suppressed for higher cooling rates. The transformation hysteresis loop was much broader in ribbons due to presence of coherent Ti rich precipitates and differences in grain size which is particularly important in the ultra small grain size range. (orig.)

Electron microscopy investigations of rapidly solidified Fe-Zr-B-Cu alloys

International Nuclear Information System (INIS)

Majumdar, B.; Arvindha Babu, D.; Akhtar, D.

2010-01-01

Rapidly solidified Fe-based nanocrystalline soft magnetic materials possess a unique combination of properties i,e high permeability, saturation and Curie temperature and very low coercivity which are otherwise not attainable in conventional soft magnetic materials. The alloys are processed by producing amorphous phase through melt spinning route followed by a partial devitrification for incorporation of nanocrystalline phase in the amorphous matrix. In this paper, detailed electron microscopic investigations of melt spun Fe-Zr-B-Cu alloys are presented. Melt spun ribbons of Fe 99-x-y Zr x BCu 1 alloys with x+y = 11 and x+y = 13 were prepared under different wheel speed conditions and then vacuum annealed for 1 h at different temperatures. The microstructure changes from completely amorphous to a cellular/dendritic bcc solid solution coexisting with the amorphous phase at intercellular/dendritic regions when Zr/B ratio or the process parameters are varied. Annealing leads to the precipitation of nanocrystalline bcc-Fe phase from both amorphous phase and already existing bcc solid solution. (author)

Microstructure of rapidly solidified Al2O3-dispersion-strengthened Type 316 stainless steel

International Nuclear Information System (INIS)

Megusar, J.; Arnberg, L.; Vander Sande, J.B.; Grant, N.J.

1981-01-01

An aluminum oxide dispersion strengthened 316 stainless steel was developed by surface oxidation. Surface oxidation was chosen as a preferred method in order to minimize formation of less stable chromium oxides. Ultra low C+N 316 stainless steel was alloyed with 1 wt % Al, rapidly solidified to produce fine powders and attrited to approximately 0.5 μm thick flakes to provide for surface oxidation. Oxide particles in the extruded material were identified mostly as Al oxides. In the preirradiated condition, oxide dispersion retarded crystallization and grain growth and had an effect on room temperature tensile properties. These structural modifications are expected to have an effect on the swelling resistance, structure stability and high temperature strength of austenitic stainless steels

Study on metal material corrosion behavior of packaging of cement solidified form

International Nuclear Information System (INIS)

He Zhouguo; Lin Meiqiong; Fan Xianhua

1997-01-01

The corrosion behavior of A3 carbon steel is studied by the specimens that are exposed to atmosphere, embedded in cement solidified form or immersed in corrosion liquid. The corrosion rate is determined by mass change of the specimens. In order to compare the corrosion resistant performance of various coatings, the specimens painted with various material such as epoxide resin, propionic acid resin, propane ether resin and Ti-white paint are tested. The results of the tests show that corrosion rate of A3 carbon steel is less than 10 -3 mm·a -1 in the atmosphere and the cement solidified from, less than 0.1 mm·a -1 in the corrosion liquids, and pH value in the corrosion liquids also affect the corrosion rate of A3 carbon steel. The corrosion resistant performance of Ti-white paint is better than that of other paints. So, A3 carbon steel as packaging material can meet the requirements during storage

Effect of Bi-content on hardness and micro-creep behavior of Sn-3.5Ag rapidly solidified alloy

Energy Technology Data Exchange (ETDEWEB)

Kamal, M. [Metal Physics Laboratory, Faculty of Science, Mansoura University (Egypt); Gouda, El Said [Metal Physics Laboratory, Department of Solid State Physics, Physics Division, National Research Center, Dokki, Giza (Egypt); Marei, L.K. [Faculty of Petroleum and Mining Engineering, Suez Canal University, Suez (Egypt)

2009-12-15

In the present paper, the influence of 1, 3, 5 and 10 % Bi (weight %) as ternary additions on structure, melting and mechanical properties of rapidly solidified Sn-3.5Ag alloy has been investigated. The effect of Bi was discussed based on the experimental results. The experimental results showed that the alloys of Sn-3.5Ag, Sn-3.5Ag-1Bi and Sn-3.5Ag-3Bi are composed of two phases; Ag{sub 3}Sn IMC embedded in Sn matrix phase, which indicated that the solubility of Bi phase in Sn-matrix was extended to 3 % as a result of rapid solidification. Bi precipitation in Sn matrix was only observed in Sn-3.5Ag-5Bi and Sn-3.5Ag-10Bi alloys. Also, addition of Bi decreased continuously the melting point of the eutectic Sn-3.5Ag alloy to 202.6 C at 10 % Bi. Vickers hardness of Sn-3.5Ag rapidly solidified alloy increased with increasing Bi content up to 3 % due to supersaturated solid solution strengthening hardening mechanism of Bi phase in Sn matrix, while the alloys contain 5 and 10 % Bi exhibited lower values of Vickers hardness. The lower values can be attributed to the precipitation of Bi as a secondary phase which may form strained regions due to the embrittlement of Bi atom. In addition, the effect of Bi addition on the micro-creep behavior of Sn-3.5Ag alloy as well as the creep rate have been described and has been calculated at room temperature. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Effects of partial crystallinity and quenched-in defects on corrosion of ...

Indian Academy of Sciences (India)

Rapid solidification by planar flow casting has been found to have introduced deficiencies, viz. partial crystallinity, air pockets and compositional difference in the ribbons of rapidly solidified Ti42.9-Cu57.1 alloy. In order to investigate the effects of these deficiencies on the corrosion of rapidly solidified Ti42.9-Cu57.1 alloy ...

The influence of Si and V on the kinetics of phase transformation and microstructure of rapidly solidified Al-Fe-Zr alloys

OpenAIRE

Karpe B.; Kosec B.; Nagode A.; Bizjak M.

2013-01-01

The influence of Si and V on the precipitation kinetics of the rapidly solidified (RS) Al-Fe-Zr alloys is presented. Precipitation kinetics and microstructural development of RS Al-Fe-Zr alloys with Si or V addition have been investigated by the combination of four point electrical resistance measurement, optical microscopy, transmition electron microscopy (TEM) and scanning electron microscopy (SEM). For verification of the electrical resistivity measurement results differential scanni...

Phase formation kinetics, hardness and magnetocaloric effect of sub-rapidly solidified LaFe11.6Si1.4 plates during isothermal annealing

Science.gov (United States)

Dai, Yuting; Xu, Zhishuai; Luo, Zhiping; Han, Ke; Zhai, Qijie; Zheng, Hongxing

2018-05-01

High-temperature phase transition behavior and intrinsic brittleness of NaZn13-type τ1 phase in La-Fe-Si magnetocaloric materials are two key problems from the viewpoint of materials production and practical applications. In the present work, the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation was introduced to quantitatively characterize the formation kinetics of τ1 phase in sub-rapidly solidified LaFe11.6Si1.4 plates during the isothermal annealing process. Avrami index was estimated to be 0.43 (∼0.5), which suggests that the formation of τ1 phase is in a diffusion-controlled one-dimensional growth mode. Meanwhile, it is found that the Vickers hardness as a function of annealing time for sub-rapidly solidified plates also agrees well with the JMAK equation. The Vickers hardness of τ1 phase was estimated to be about 754. Under a magnetic field change of 30 kOe, the maximum magnetic entropy change was about 22.31 J/(kg·K) for plates annealed at 1323 K for 48 h, and the effective magnetic refrigeration capacity reached 191 J/kg.

Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

International Nuclear Information System (INIS)

Wolf, W.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J.

2016-01-01

The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al 71 Co 13 Fe 8 Cr 8 , Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al 71 Co 13 Fe 8 Cr 8 alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al 71 Co 13 Fe 8 Cr 8 . The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al 5 Co 2 and Al 13 Co 4 and are quasicrystalline approximants. Although the Al 5 Co 2 phase has already been reported in the Al 71 Co 13 Fe 8 Cr 8 alloy, the presence of the monoclinic Al 13 Co 4 is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al 13 Co 4 phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al 71 Co 13 Fe 8 Cr 8 alloy, the compositions Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were chosen to be within the region of formation of the quaternary extension of the Al 13 Co 4 phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system, around the compositions studied, is composed of quaternary extensions of Al-Co intermetallic phases, which present solubility of Fe and Cr at Co atomic sites. - Highlights: •The Al rich region of the Al

Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

Energy Technology Data Exchange (ETDEWEB)

Wolf, W., E-mail: witorw@gmail.com [Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Bolfarini, C., E-mail: cbolfa@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Kiminami, C.S., E-mail: kiminami@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Botta, W.J., E-mail: wjbotta@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil)

2016-12-15

The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}, Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}. The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al{sub 5}Co{sub 2} and Al{sub 13}Co{sub 4} and are quasicrystalline approximants. Although the Al{sub 5}Co{sub 2} phase has already been reported in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the presence of the monoclinic Al{sub 13}Co{sub 4} is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al{sub 13}Co{sub 4} phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the compositions Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were chosen to be within the region of formation of the quaternary extension of the Al{sub 13}Co{sub 4} phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system

Tensile behavior change depending on the microstructure of a Fe-Cu alloy produced from rapidly solidified powder

International Nuclear Information System (INIS)

Kakisawa, Hideki; Minagawa, Kazumi; Halada, Kohmei

2003-01-01

The relationship between consolidating temperature and the tensile behavior of iron alloy produced from Fe-Cu rapidly solidified powder is investigated. Fe-Cu powder fabricated by high-pressure water atomization was consolidated by heavy rolling at 873-1273 K. Microstructural changes were observed and tensile behavior was examined. Tensile behavior varies as the consolidating temperature changes, and these temperature-dependent differences depend on the morphology of the microstructure on the order of micrometers. The sample consolidated at 873 K shows a good strength/elongation balance because the powder microstructure and primary powder boundaries are maintained. The samples consolidated at the higher temperatures have a microstructure of recrystallized grains, and these recrystallized samples show the conventional relationship between tensile behavior and grain size in ordinal bulk materials

Synthesis of laser beam rapidly solidified novel surfaces on D2 tool steel

International Nuclear Information System (INIS)

Ahmed, B.A.; Rizwan, K.F.; Minhas, J.A.; Waheed-ul-Haq, S.; Shahid, M.

2011-01-01

Surface layer of D2 tool steel was subjected to laser surface melting using continuous wave 2.5 kW CO/sub 2/ laser in point source melting mode. The processing parameters were varied to achieve a uniform depth of around 2 mm. Microstructural study revealed epitaxial growth of fine dendritic structure with secondary dendrite arm spacing in the range of 20-25 mu m. The phases in the parent annealed sample were BCC ferrite and chromium rich M7C3 carbide. The major phase after laser treatment was austenite and M7C3. The average hardness of annealed sample was 195 HV which increased to 410 HV after laser melting. Corrosion studies in 2% HCl solution exhibited a drastic improvement in corrosion resistance in laser treated samples. Improvement in properties is attributed to the refinement and uniformity of microstructure in the rapidly solidified surface. The case of a moving heat source was subjected to computer aided simulation to predict the melt depth at different processing conditions in point source melting mode. The calculated depths using the model, in ABAQUS software was found in good agreement with the experimental data. (author)

Microstructure and high-temperature oxidation resistance of TiN/Ti3Al intermetallic matrix composite coatings on Ti6Al4V alloy surface by laser cladding

Science.gov (United States)

Zhang, Xiaowei; Liu, Hongxi; Wang, Chuanqi; Zeng, Weihua; Jiang, Yehua

2010-11-01

A high-temperature oxidation resistant TiN embedded in Ti3Al intermetallic matrix composite coating was fabricated on titanium alloy Ti6Al4V surface by 6kW transverse-flow CO2 laser apparatus. The composition, morphology and microstructure of the laser clad TiN/Ti3Al intermetallic matrix composite coating were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high-temperature oxidation resistance of the composite coatings and the titanium alloy substrate, isothermal oxidation test was performed in a conventional high-temperature resistance furnace at 600°C and 800°C respectively. The result shows that the laser clad intermetallic composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like, and dendrites), and uniformly distributed in the Ti3Al matrix. It indicates that a physical and chemical reaction between the Ti powder and AlN powder occurred completely under the laser irradiation. In addition, the microhardness of the TiN/Ti3Al intermetallic matrix composite coating is 844HV0.2, 3.4 times higher than that of the titanium alloy substrate. The high-temperature oxidation resistance test reveals that TiN/Ti3Al intermetallic matrix composite coating results in the better modification of high-temperature oxidation behavior than the titanium substrate. The excellent high-temperature oxidation resistance of the laser cladding layer is attributed to the formation of the reinforced phase TiN and Al2O3, TiO2 hybrid oxide. Therefore, the laser cladding TiN/Ti3Al intermetallic matrix composite coating is anticipated to be a promising oxidation resistance surface modification technique for Ti6Al4V alloy.

Rapid detection of TiO2 (E171) in table sugar using Raman spectroscopy.

Science.gov (United States)

Tan, Chen; Zhao, Bin; Zhang, Zhiyun; He, Lili

2017-02-01

The potential toxic effects of titanium dioxide (TiO 2 ) to humans remain debatable despite its broad application as a food additive. Thus, confirmation of the existence of TiO 2 particles in food matrices and subsequently quantifying them are becoming increasingly critical. This study developed a facile, rapid (E171) from food products (e.g., table sugar) by Raman spectroscopy. To detect TiO 2 particles from sugar solution, sequential centrifugation and washing procedures were effectively applied to separate and recover 97% of TiO 2 particles from the sugar solution. The peak intensity of TiO 2 sensitively responded to the concentration of TiO 2 with a limit of detection (LOD) of 0.073 mg kg -1 . In the case of sugar granules, a mapping technique was applied to directly estimate the level of TiO 2 , which can be potentially used for rapid online monitoring. The plot of averaged intensity to TiO 2 concentration in the sugar granules exhibited a good linear relationship in the wide range of 5-2000 mg kg -1 , with an LOD of 8.46 mg kg -1 . Additionally, we applied Raman spectroscopy to prove the presence of TiO 2 in sugar-coated doughnuts. This study begins to fill in the analytical gaps that exist regarding the rapid detection and quantification of TiO 2 in food, which facilitate the risk assessment of TiO 2 through food exposure.

Method of solidifying radioactive solid wastes

International Nuclear Information System (INIS)

Fukazawa, Tetsuo; Kawamura, Fumio; Kikuchi, Makoto.

1984-01-01

Purpose: To obtain solidification products of radioactive wastes satisfactorily and safely with no destruction even under a high pressure atmosphere by preventing the stress concentration by considering the relationships of the elastic module between the solidifying material and radioactive solid wastes. Method: Solidification products of radioactive wastes with safety and securing an aimed safety ratio are produced by conditioning the modules of elasticity of the solidifying material equal to or less than that of the radioactive wastes in a case where the elastic module of radioactive solid wastes to be solidified is smaller than that of the solidifying material (the elastic module of wastes having the minimum elastic module among various wastes). The method of decreasing the elastic module of the solidifying material usable herein includes the use of such a resin having a long distance between cross-linking points of a polymer in the case of plastic solidifying materials, and addition of rubber-like binders in the case of cement or like other inorganic solidifying materials. (Yoshihara, H.)

Method of solidifying radioactive laundry wastes

International Nuclear Information System (INIS)

Yasumura, Keijiro

1984-01-01

Purpose: To enable to solidify radioactive laundry wastes containing non-ionic liquid detergents less solidifiable by plastic solidification process in liquid laundry wastes for cloths or the likes discharged from a nuclear power plant. Method: Radioactive laundry wastes are solidified by using plastic solidifying agent comprising, as a main ingredient, unsaturated polyester resins and methylmethacrylate monomers. The plastic solidifying agents usable herein include, for example, unsaturated polyester resins prepared by condensating maleic anhydride and phthalic anhydride with propylene glycol and incorporated with methylmethacrylate monomers. The mixing ratio of the methylmethacrylate monomers is preferably 30 % by weight based on the unsaturated polyester resins. (Aizawa, K.)

Growth and microstructure formation of isothermally-solidified Zircaloy-4 joints brazed by a Zr-Ti-Cu-Ni amorphous alloy ribbon

Science.gov (United States)

Kim, K. H.; Lim, C. H.; Lee, J. G.; Lee, M. K.; Rhee, C. K.

2013-10-01

The microstructure and growth characteristics of Zircaloy-4 joints brazed by a Zr48Ti16Cu17Ni19 (at.%) amorphous filler metal have been investigated with regard to the controlled isothermal solidification and intermetallic formation. Two typical joints were produced depending on the isothermal brazing temperature: (1) a dendritic growth structure including bulky segregation in the central zone (at 850 °C), and (2) a homogeneous dendritic structure throughout the joint without segregation (at 890 °C). The primary α-Zr phase was solidified isothermally, nucleating to grow into a joint with a cellular or dendritic structure. Also, the continuous Zr2Ni and particulate Zr2Cu phases were formed in the segregated center zone and at the intercellular region, respectively, owing to the different solubility and atomic mobility of the solute elements (Ti, Cu, and Ni) in the α-Zr matrix. A disappearance of the central Zr2Ni phase was also rate-controlled by the outward diffusion of the Cu and Ni elements. When the detrimental Zr2Ni intermetallic phase was eliminated by a complete isothermal solidification at 890 °C, the strengths of the joints were high enough to cause yielding and fracture in the base metal, exceeding those of the bulk Zircaloy-4, at room temperature as well as at elevated temperatures (up to 400 °C).

Rapid thermal annealing of Ti-rich TiNi thin films: A new approach to fabricate patterned shape memory thin films

International Nuclear Information System (INIS)

Motemani, Y.; Tan, M.J.; White, T.J.; Huang, W.M.

2011-01-01

This paper reports the rapid thermal annealing (RTA) of Ti-rich TiNi thin films, synthesized by the co-sputtering of TiNi and Ti targets. Long-range order of aperiodic alloy could be achieved in a few seconds with the optimum temperature of 773 K. Longer annealing (773 K/240 s), transformed the film to a poorly ordered vitreous phase, suggesting a novel method for solid state amorphization. Reitveld refinement analyses showed significant differences in structural parameters of the films crystallized by rapid and conventional thermal annealing. Dependence of the elastic modulus on the valence electron density (VED) of the crystallized films was studied. It is suggested that RTA provides a new approach to fabricate patterned shape memory thin films.

Radioactive waste solidifying material

International Nuclear Information System (INIS)

Ono, Keiichi; Sakai, Etsuro.

1989-01-01

The solidifying material according to this invention comprises cement material, superfine powder, highly water reducing agent, Al-containing rapid curing material and coagulation controller. As the cement material, various kinds of quickly hardening, super quickly hardening and white portland cement, etc. are usually used. As the superfine powder, those having average grain size smaller by one order than that of the cement material are desirable and silica dusts, etc. by-produced upon preparing silicon, etc. are used. As the highly water reducing agent, surface active agents of high decomposing performance and comprising naphthalene sulfonate, etc. as the main ingredient are used. As the Al-containing rapidly curing material, calcium aluminate, etc. is used in an amount of less than 10 parts by weight based on 100 parts by weight of the powdery body. As the coagulation controller, boric acid etc. usually employed as a retarder is used. This can prevent dissolution or collaption of pellets and reduce the leaching of radioactive material. (T.M.)

Morphological variants of carbides of solidification origin in the rapidly solidified powder particles of hypereutectic iron alloy

International Nuclear Information System (INIS)

Kusy, M.; Grgac, P.; Behulova, M.; Vyrostkova, A.; Miglierini, M.

2004-01-01

The paper deals with the analysis of the morphological variants of solidification microstructures and vanadium rich M 4 C 3 carbide phases in the rapidly solidified (RS) powder particles from hypereutectic Fe-C-Cr-V alloy prepared by the nitrogen gas atomisation. Five main types of solidification microstructures were identified in RS particles: microstructure with globular carbides, microstructure with globular and star-like carbides, microstructure with primary carbides in the centres of eutectic colonies, microstructure with eutectic colonies without primary carbides and microstructure with eutectic spherulites. Based on the morphological features of carbide phases and the thermal history of RS particles, the microstructures were divided into two groups - microstructures morphologically affected and non-affected during the post-recalescence period of solidification. Thermophysical reasons for the morphologically different M 4 C 3 carbide phases development in the RS powder particles are discussed

Effect of rapid thermal annealing on the composition of Au/Ti/Al/Ti ohmic contacts for GaN-based microdevices

International Nuclear Information System (INIS)

Redondo-Cubero, A.; Ynsa, M.D.; Romero, M.F.; Alves, L.C.; Muñoz, E.

2013-01-01

The homogeneity of Au/Ti/Al/Ti ohmic contacts for AlGaN/GaN devices was analyzed as a function of the thickness of the Ti barrier (30 nm 50 nm, although several compositional deficiencies were identified in the distribution maps obtained with the ion microprobe, including the formation of craters. A clear interplay between Ti and Au was found, suggesting the relevance of lateral flows during the rapid thermal annealing

Microstructure and mechanical properties of a novel rapidly solidified, high-temperature Al-alloy

Energy Technology Data Exchange (ETDEWEB)

Overman, N.R., E-mail: Nicole.Overman@pnnl.gov [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); Mathaudhu, S.N. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); University of California, Riverside, 3401 Watkins Dr., Riverside, CA 92521 (United States); Choi, J.P.; Roosendaal, T.J.; Pitman, S. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States)

2016-02-15

Rapid solidification (RS) processing, as a production method, offers a variety of unique properties based on far-from-equilibrium microstructures obtained through rapid cooling rates. In this study, we seek to investigate the microstructures and properties of a novel Al-alloy specifically designed for high temperature mechanical stability. Synthesis of, AlFe{sub 11.4}Si{sub 1.8}V{sub 1.6}Mn{sub 0.9} (wt.%), was performed by two approaches: rotating cup atomization (“shot”) and melt spinning (“flake”). These methods were chosen because of their ability to produce alloys with tailored microstructures due to their inherent differences in cooling rate. The as-solidified precursor materials were microstructurally characterized with electron microscopy. The results show that the higher cooling rate flake material exhibited the formation of nanocrystalline regions as well additional phase morphologies not seen in the shot material. Secondary dendritic branching in the flake material was on the order of 0.1–0.25 μm whereas branching in the shot material was 0.5–1.0 μm. Consolidated and extruded material from both precursor materials was mechanically evaluated at both ambient and high (300 °C) temperature. The consolidated RS flake material is shown to exhibit higher strengths than the shot material. The ultimate tensile strength of the melt spun flake was reported as 544.2 MPa at room temperature and 298.0 MPa at 300 °C. These results forecast the ability to design alloys and processing approaches with unique non-equilibrium microstructures with robust mechanical properties at elevated temperatures. - Highlights: • A novel alloy, AlFe{sub 11.4}Si{sub 1.8}V{sub 1.6}Mn{sub 0.9} was fabricated by rapid solidification. • Room temperature yield strength exceeded 500 MPa. • Elevated temperature (300 °C) yield strength exceeded 275 MPa. • Forging, after extrusion of the alloy resulted in microstructural coarsening. • Decreased strength and ductility was

Short-term thermal response of rapidly solidified Type 304 stainless steel containing helium

International Nuclear Information System (INIS)

Clark, D.E.

1988-06-01

Type 304 stainless steel was heat treated for short times near its melting point in order to determine its microstructural response to thermal cycles typical of the near heat-affected zones of welding processes. The material was rapidly solidified as a powder by centrifugal atomization in a helium environment and consolidated by hot extrusion. Along with the ingot metallurgy material used for canning the powder prior to hot extrusion, it was heat treated using a Gleeble at temperatures of 1200 and 1300 degree C for times ranging from <1 to 1000 s, and the samples were examined for microstructure and the existence of porosity due to entrapped helium. At higher test temperatures and longer treatment times, the material developed extensive porosity, which was stabilized by the presence of helium and which may also have a role in anchoring grain boundaries and inhibiting grain growth. The powder material. At lower test temperatures and shorter treatment times, grain growth in the γ phase appeared to be restricted in the powder material, possible by the presence of helium. An intermediate temperatures and times, a γ-δ duplex microstructure also restricted grain growth again occurred in the δ microstructure. 9 refs., 14 figs., 3 tabs

Effect of processing on the microstructural development in a rapidly solidified Al-Fe-V-Si alloy

International Nuclear Information System (INIS)

Srivastava, A.K.; Ranganathan, S.; Ojha, S.N.

1993-01-01

An Al 80 Fe 10 Si 6 alloy has been rapidly solidified using melt spinning, gas atomization and spray forming processes. The effect of processing techniques on the microstructural characteristics of the alloy has ben evaluated. The melt spun alloy has shown an icosahedral quasicrystalline phase surrounded by a rational approximant structure of the icosahedral phase. The rational approximant structure has been identified as a crystalline cubic silicide phase. The atomized powders have exhibited cellular and dendritic morphology depending on the size of particles. In addition, the second phase particles of the silicide phase are observed to decorate the cell boundaries and interdendritic regions. In contrast, the alloy processed by spray deposition has revealed an equiaxed solidification morphology with a uniform dispersion of find silicon phase inside the grain. The origin of the microstructure in the alloy processed by these techniques is discussed. The results are compared wherever possible with the commercially available Al-Fe-V-Si alloys

Liquid wastes concentrating and solidifying device

International Nuclear Information System (INIS)

Kamiyoshi, Hideki; Ninokata, Yoshihide.

1985-01-01

Purpose: To provide a device for concentrating to solidify radioactive liquid wastes at large solidifying speed and with high decontaminating coefficient, without requirement for automatic control. Constitution: An asphalt solidifying device is disposed below a centrifugal thin film drier, and powder resulted from the drier is directly solidified with asphalt by utilizing the rotation of the drier for the mixing operation in the asphalt vessel. If abnormality should occur in the operation of the drier, resulting liquid wastes can be received and solidified in the asphalt vessel. The liquid wastes are heated to dry in a vessel main body having the heating surface at the circumferential surface. The vessel main body provided with a nozzle for supplying liquid to be treated disposed slantwise at the upper portion of the heating face, scrapers which rotate and slidingly contact the heating face and nozzles which jet out chemicals to the heating face behind the scrapers. Below the vessel main body, are disposed a funnel-like hopper for receiving falling scales, rotary vanes, and the likes by which the scales are introduced into the asphalt solidifying vessel. (Moriyama, K.)

Microstructure/processing relationships in high-energy high-rate consolidated powder composites of Nb-stabilized Ti3Al+TiAl

Energy Technology Data Exchange (ETDEWEB)

Persad, C.; Lee, B.; Hou, C.; Eliezer, Z.; Marcus, H.L.

1989-01-01

A new approach to powder processing is employed in forming titanium aluminide composites. The processing consists of internal heating of a customized powder blend by a fast electrical discharge of a homopolar generator. The high-energy high-rate '1MJ in 1s' pulse permits rapid heating of an electrically conducting powder mixture in a cold wall die. This short time at temperature approach offers the opportunity to control phase transformations and the degree of microstructural coarsening not readily possible with standard powder-processing approaches. This paper describes the consolidation results of titanium aluminide-based powder-composite materials. The focus of this study was the definition of microstructure/processing relationships for each of the composite constituents, first as monoliths and then in composite forms. Non-equilibrium phases present in rapidly solidified TiAl powders are transformed to metastable intermediates en route to the equilibrium gamma phase.

Radioactive liquid waste solidifying device

International Nuclear Information System (INIS)

Uchiyama, Yoshio.

1987-01-01

Purpose: To eliminate the requirement for discharge gas processing and avoid powder clogging in a facility suitable to the volume-reducing solidification of regenerated liquid wastes containing sodium sulfate. Constitution: Liquid wastes supplied to a liquid waste preheater are heated under a pressure higher than the atmospheric pressure at a level below the saturation temperature for that pressure. The heated liquid wastes are sprayed from a spray nozzle from the inside of an evaporator into the super-heated state and subjected to flash distillation. They are further heated to deposit and solidify the solidification components in the solidifying evaporation steams. The solidified powder is fallen downwardly and heated for removing water content. The recovered powder is vibrated so as not to be solidified and then reclaimed in a solidification storage vessel. Steams after flash distillation are separated into gas, liquid and solids by buffles. (Horiuchi, T.)

Solidifying processing device for radioactive waste

International Nuclear Information System (INIS)

Sueto, Kumiko; Toyohara, Naomi; Tomita, Toshihide; Sato, Tatsuaki

1990-01-01

The present invention concerns a solidifying device for radioactive wastes. Solidifying materials and mixing water are mixed by a mixer and then charged as solidifying and filling materials to a wastes processing container containing wastes. Then, cleaning water is sent from a cleaning water hopper to a mixer to remove the solidifying and filling materials deposited in the mixer. The cleaning liquid wastes are sent to a separator to separate aggregate components from cleaning water components. Then, the cleaning water components are sent to the cleaning water hopper and then mixed with dispersing materials and water, to be used again as the mixing water upon next solidifying operation. On the other hand, the aggregate components are sent to a processing mechanism as radioactive wastes. With such procedures, since the discharged wastes are only composed of the aggregates components, and the amount of the wastes are reduced, facilities and labors for the processing of cleaning liquid wastes can be decreased. (I.N.)

Method of solidifying radioactive waste

International Nuclear Information System (INIS)

Hasegawa, Akira; Mihara, Shigeru; Yamashita, Koji; Sauda, Kenzo.

1988-01-01

Purpose: To obtain satisfactory plastic solidification products rapidly and more conveniently from radioactive wastes. Method: liquid wastes contain, in addition to sodium sulfate as the main ingredient, nitrates hindering the polymerizing curing reactions and various other unknown ingredients, while spent resins contain residual cationic exchange groups hindering the polymerizing reaction. Generally, as the acid value of unsaturated liquid polyester resins is lower, the number of terminal alkyd resins is small, formation of nitrates is reduced and the polymerizing curing reaction is taken place more smoothly. In view of the above, radioactive wastes obtained by dry powderization or dehydration of radioactive liquid wastes or spent resins are polymerized with unsaturated liquid polyester resins with the acid value of less than 13 to obtain plastic solidification. Thus, if the radioactive wastes contain a great amount of polymerization hindering material such as NaNO 2 , they can be solidified rapidly and conveniently with no requirement for pre-treatment. (Kamimura, Y.)

Effect of Trace Ce on Microstructure and Properties of Near-rapidly Solidified Al-Zn-Mg-Cu Alloys

Directory of Open Access Journals (Sweden)

HUANG Gao-ren

2018-03-01

Full Text Available Through using DSC, XRD, SEM, EDS, static tensile test and other analysis methods of materials, the effect of trace Ce on microstructure and properties of near-rapidly solidified Al-Zn-Mg-Cu alloy was studied in order to find out rational homogenizing heat treatment process. The results show that Ce plays a role of refining grain and purifying molten alloy. The addition of Ce reduces dendritic spacing, refines the grain structures, eliminates dispersed shrinkage. The addition of Ce reduces the initial melting point of low melting eutectic phases by 3℃, under the same homogenization conditions. Trace Ce promotes the dissolution of low melting eutectic phases into the matrix, which improves the effect of homogenization. Homogenization temperatures of alloy A should be lower than 480℃and alloy B should be lower than 470℃; the addition of Ce decreases the homogenization temperature and improves the homogenization effect. The addition of Ce also greatly increases the tensile strength of the alloys.

RAPIDLY-SOLIDIFIED PERMANENT MAGNET MATERIALS: FACTORS AFFECTING QUENCHABILITY AND MAGNETIC PROPERTIES IN Nd2Fe14B

International Nuclear Information System (INIS)

LEWIS, L.H.; KRAMER, M.J.; MCCALLUM, R.W.; BRANAGAN, D.J.

1999-01-01

Insight into the solidification behavior of Nd 2 Fe 14 B-based materials processed by rapid solidification techniques has been obtained by a systematic experimental study of the Curie temperatures of selected phases found in these materials. Nd 2 Fe 14 B-based materials fabricated by two disparate rapid solidification techniques, inert gas atomization (IGA) and melt-spinning, has been studied. The compositions of the starting materials have been altered with additions of the refractory elements Ti and C which are known to alter the solidification behavior of these materials. Special emphasis has been placed on trying to understand the effect of alloying additions upon the nature of the quenched glass, the distribution of the elemental additions within the Nd 2 Fe 14 B lattice and the evolution of the elemental partitioning with quench rate and annealing condition. The experimental Curie temperature data obtained using thermal analysis methods from the particles produced by gas-atomization is consistent with both an ejection of quenched-in refractory species from the crystalline Nd 2 Fe 14 B lattice and with increased crystallographic order as particle size, and hence grain size, increases. Magnetic ac susceptibility measurements performed on nominally-amorphous Nd 2 Fe 14 B ribbons produced by melt-spinning indicate a decrease of the Curie temperature with increasing quench rate, a result that may be attributed either to the degree of Ti/C retention in the glass or to the degree of disorder in the glass, independent of Ti/C retention

Valence electron structure analysis of the cubic silicide intermetallics in rapidly solidified Al-Fe-V-Si alloy

International Nuclear Information System (INIS)

Wang, J.Q.; Qian, C.F.; Zhang, B.J.; Tseng, M.K.; Xiong, S.W.

1996-01-01

The application of rapid solidification for the development of elevated temperature aluminum alloys has resulted in the emergence of several alloys based on the Al-Fe alloy system. Of particular interest are Al-Fe-V-Si alloys which have excellent room temperature and high temperature mechanical properties. In a pioneering study, Skinner et al. showed the stabilization of the cubic phase in ternary Al-Fe-Si alloy by the addition of a quaternary element, vanadium. The evolution of the microstructure in these alloys both during rapid solidification and subsequent processing is of crucial importance. Kim has demonstrated that the composition of the silicide phase in rapidly solidified Al-Fe-V-Si alloy is very close to Al 12 (Fe,V) 3 Si with the body centered cubic (bcc) structure. The structure is closely related to that of quasicrystals.In view of the structural features and the relationship between the α 12 and α 13 phases, the researching emphasis should firstly be put on the α 12 phase. In this paper the authors analyzed the α -(AlFeSi)(α 12 -type) phase from the angle of atomic valence electron structure other than the traditional methods of obtaining the diffraction spots of the phase. Several pieces of information were obtained about the hybrid levels and bond natures of every kind of atom in the α -(AlFeSi) phase. Finally the authors explained the phenomenon which V atom can substitute for Fe atom in the α 12 phase and improve the thermal stability of the phase in Al-Fe-V-Si alloy

Microstructures and martensitic transformation behavior of superelastic Ti-Ni-Ag scaffolds

Energy Technology Data Exchange (ETDEWEB)

Li, Shuanglei; Kim, Eun-soo [School of Materials Science and Engineering & ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Kim, Yeon-wook [Department of Material Engineering, Keimyung University, 1000 Shindang-dong, Dalseo-gu, Daegu 704-701 (Korea, Republic of); Nam, Tae-hyun, E-mail: tahynam@gnu.ac.kr [School of Materials Science and Engineering & ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of)

2016-10-15

Highlights: • The B2-R-B19′ transformation occurred in 49Ti-50.3Ni-0.7Ag alloy fibers. • Annealing treated alloy fibers showed superelastic recovery ratio of 93%. • Ageing treated scaffold had an elastic modulus of 0.67 GPa. • Ageing treated scaffold exhibited good superelasticity at human body temperature. - Abstract: Ti-Ni-Ag scaffolds were prepared by sintering rapidly solidified alloy fibers. Microstructures and transformation behaviors of alloy fibers and scaffolds were investigated by means of electron probe micro-analyzer (EPMA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The B2-R-B19′ transformation occurs in alloy fibers. The alloy fibers have good superelasticity with superelastic recovery ratio of 93% after annealing heat treatment. The as-sintered Ti-Ni-Ag scaffolds possess three-dimensional and interconnected pores and have the porosity level of 80%. The heat treated Ti-Ni-Ag scaffolds not only have an elastic modulus of 0.67 GPa, which match well with that of cancellous bone, but also show excellent superelasticity at human body temperature. In terms of the mechanical properties, the Ti-Ni-Ag scaffolds in this study can meet the main requirements of bone scaffold for the purpose of bone replacement applications.

Phase transformation in rapidly quenched Fe-Cr-Co-Mo-Ti-Si-B alloys

Science.gov (United States)

Zhukov, D. G.; Shubakov, V. S.; Zhukova, E. Kh; Gorshenkov, M. V.

2018-03-01

The research results of phase transformations in Fe-24Cr-16Co-3Mo-0.2Ti-1Si-B alloys (with a boron content of 1 to 3% by mass) obtained by rapid quenching are presented. The structure formation regularities during the melt spinning and during the subsequent crystallization annealing in rapidly quenched bands of the Fe-Cr-Co-Mo-Ti-Si-B system alloys were studied. The changes in the phase composition of the rapidly quenched Fe-Cr-Co-Mo-Ti- Si-B system alloys after quenching at various quench rates and at different boron concentrations in the alloys are studied. It is shown that during crystallization from an amorphous state, at temperatures above 570 °C, in addition to the α-phase, the σ-phase appears first, followed by the γ-phase. Heat treatment of rapidly quenched bands to high-coercive state was carried out. A qualitative assessment of magnetic properties in a high-coercivity state was carried out. An evaluation of the level of magnetic properties in a high-coercivity state allows us to conclude that the application of a magnetic field during crystallization from an amorphous state leads to anisotropy of the magnetic properties, that is, an anisotropic effect of thermo-magnetic treatment is detected.

Solidified structure of thin-walled titanium parts by vertical centrifugal casting

Directory of Open Access Journals (Sweden)

Wu Shiping

2011-05-01

Full Text Available The solidified structure of the thin-walled and complicated Ti-6Al-4V castings produced by the vertical centrifugal casting process was studied in the present work. The results show that the wall thickness of the section is featured with homogeneously distributed fine equiaxial grains, compared with the microstructure of the thick-walled section. The grain size of the castings has a tendency to decrease gradually with the increasing of the centrifugal radius. The inter-lamellar space in thick-walled casting parts is bigger than that of the thin-walled parts, and the profile of inter-lamellar space is not susceptible to the centrifugal radius.

Microstructure and high temperature oxidation resistance of in-situ synthesized TiN/Ti_3Al intermetallic composite coatings on Ti6Al4V alloy by laser cladding process

International Nuclear Information System (INIS)

Liu, Hongxi; Zhang, Xiaowei; Jiang, Yehua; Zhou, Rong

2016-01-01

High temperature anti-oxidation TiN/Ti_3Al intermetallic composite coatings were fabricated with the powder and AlN powder on Ti6Al4V titanium alloy surface by 6 kW transverse-flow CO_2 laser apparatus. The chemical composition, morphology and microstructure of the TiN/Ti_3Al composite coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high temperature oxidation resistance of TiN/Ti_3Al coating, the isothermal oxidation test was performed in a high temperature resistance furnace at 600 °C and 800 °C, respectively. The result shows that the composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like or dendrites), with an even distribution in Ti_3Al matrix. It indicates that a physical and chemical reaction between Ti powder and AlN powder has completely occurred under the laser irradiation condition. In addition, the microhardness of the TiN/Ti3Al intermetallic composite coating is 3.4 times higher than that of the Ti6Al4V alloy substrate and reaches 844 HV_0_._2. The high temperature oxidation behavior test reveals that the high temperature oxidation resistance of TiN/Ti_3Al composite coating is much better than that of titanium alloy substrate. The excellent high temperature oxidation resistance of TiN/Ti_3Al intermetallic composite coating is attributed to the formation of reinforced phases TiN, Al_2O_3 and TiO_2. The laser cladding TiN/Ti_3Al intermetallic composite coating is anticipated to be a promising high temperature oxidation resistance coating for Ti6Al4V alloy. - Highlights: • In-situ TiN/Ti_3Al composite coating was synthesized on Ti6Al4V alloy by laser cladding. • The influence of Ti and AlN molar ratio on the microstructure of the coating was studied. • The TiN/Ti_3Al intermetallic coating is mainly composed of α-Ti, TiN and Ti_3Al phases. • The

Analysis of cement solidified product and ash samples and preparation of a reference material

International Nuclear Information System (INIS)

Ishimori, Ken-ichiro; Haraga, Tomoko; Shimada, Asako; Kameo, Yutaka; Takahashi, Kuniaki

2010-08-01

Simple and rapid analytical methods for radionuclides in low-level radioactive waste have been developed by the present authors. The methods were applied to simulated solidified products and actual metal wastes to confirm their usefulness. The results were summarized as analytical guide lines. In the present work, cement solidified product and ash waste were analyzed followed by the analytical guide lines and subjects were picked up and solved for the application of the analytical guide lines to these wastes. Pulverization and homogenization method for ash waste was improved to prevent a contamination since the radioactivity concentrations of the ash samples were relatively high. Pre-treatment method was altered for the cement solidified product and ash samples taking account for their high concentration of Ca. Newly, an analytical method was also developed to measure 129 I with a dynamic reaction cell inductively coupled plasma mass spectrometer. In the analytical test based on the improved guide lines, gamma-ray emitting nuclides, 60 Co and 137 Cs, were measured to estimate the radioactivity of the other alpha and beta-ray emitting nuclides. The radionuclides assumed detectable, 3 H, 14 C, 36 Cl, 63 Ni, 90 Sr, and alpha-ray emitting nuclides, were analyzed with the improved analytical guide lines and their applicability for cement solidified product and ash samples were confirmed. Additionally a cement solidified product sample was evaluated in terms of the homogeneity and the radioactivity concentrations in order to prepare a reference material for radiochemical analysis. (author)

Glass-forming ability and stability of ternary Ni-early transition metal (Ti/Zr/Hf) alloys

Energy Technology Data Exchange (ETDEWEB)

Basu, Joysurya [Department of Metallurgy, Indian Institute of Science, Bangalore 560 012 (India); Ranganathan, S. [Department of Metallurgy, Indian Institute of Science, Bangalore 560 012 (India)]. E-mail: rangu@met.iisc.ernet.in

2006-08-15

Four Ni-bearing Ti, Zr and Hf ternary alloys of nominal composition Zr{sub 41.5}Ti{sub 41.5}Ni{sub 17}, Zr{sub 25}Ti{sub 25}Ni{sub 50}, Zr{sub 41.5}Hf{sub 41.5}Ni{sub 17} and Ti{sub 41.5}Hf{sub 41.5}Ni{sub 17} were rapidly solidified in order to produce ribbons. The Zr-Ti-Ni and Ti-Hf-Ni alloys become amorphous, whereas the Zr-Hf-Ni alloy shows precipitation of a cubic phase. The devitrification of all three alloys was followed and the relative tendency to form nanoquasicrystals and cF96 phases analysed. The relative glass-forming ability of the alloys can be explained by taking into account their atomic size difference. Addition of Ni often leads to quasicrystallisation or quasicrystal-related phases. This can be explained by the atomic radius and heat of mixing of the constituent elements. The phases precipitated at the initial stages of crystallisation indicate the possible presence of Frank-Kasper polyhedral structure in the amorphous alloys. Structural analysis reveals that the Laves and the anti-Laves phases have the same polyhedral structural unit, which is similar to the structural characteristics of glass.

Effect of TiC additions to the microstructure and magnetic properties of Nd9.5Fe84.5B6 melt-spun ribbons

International Nuclear Information System (INIS)

Kramer, M.J.; Li, C.P.; Dennis, K.W.; McCallum, R.W.; Sellers, C.H.; Branagan, D.J.; Lewis, L.H.; Wang, J.Y.

1998-01-01

Rapidly solidified samples of Nd 9.5 Fe 84.5 B 6 with and without 3 at.% TiC were prepared by melt spinning and melt extraction and then annealed in vacuum (3x10 -6 Torr) at temperatures from 600 to 750 degree C. For alloys melt spun under similar conditions, the overquenched state was achieved at wheel speeds >10 m/s for the TiC added alloy while >20 m/s was necessary without TiC. The overquenched samples contained a smaller fraction of α-Fe in smaller grains than the undercooled samples where Fe dendrites formed near the free surface during solidification. These Fe dendrites were not removed by annealing. In addition, large orientated 2-14-1 grains nucleated on the Fe dendrites. This combination is detrimental to the magnetic properties. The addition of TiC results in improved control of the microstructure over a larger fraction of the ribbon volume enhancing the magnetic properties. copyright 1998 American Institute of Physics

High-temperature deformation behavior and mechanical properties of rapidly solidified Al-Li-Co and Al-Li-Zr alloys

International Nuclear Information System (INIS)

Sastry, S.M.L.; Oneal, J.E.

1984-01-01

The deformation behavior at 25-300 C of rapidly solidified Al-3Li-0.6Co and Al-3Li-0.3Zr alloys was studied by tensile property measurements and transmission electron microscopic examination of dislocation substructures. In binary Al-3Li and Al-3Li-Co alloys, the modulus normalized yield stress increases with an increase in temperature up to 150 C and then decreases. The yield stress at 25 C of Al-3Li-0.3Zr alloys is 180-200 MPa higher than that of Al-3Li alloys. However, the yield stress of the Zr-containing alloy decreases drastically with increasing temperatures above 75 C. The short-term yield stresses at 100-200 C of the Al-3Li-based alloys are higher than that of the conventional high-temperature Al alloys. The temperature dependences of the flow stresses of the alloys were analyzed in terms of the magnitudes and temperature dependences of the various strengthening contributions in the two alloys. The dislocation substructures at 25-300 C were correlated with mechanical properties. 19 references

Evolution of the microstructure and hardness of a rapidly solidified/melt-spun AZ91 alloy upon aging at different temperatures

International Nuclear Information System (INIS)

Wang Baishu; Liu Yongbing; An Jian; Li Rongguang; Su Zhenguo; Su Guihua; Lu You; Cao Zhanyi

2009-01-01

The effect of aging at different temperatures on a rapidly solidified/melt-spun AZ91 alloy has been investigated in depth. The microstructures of as-spun and aged ribbons with a thickness of approximately 60 μm were characterized using X-ray diffraction, transmission electron microscopy and laser optical microscopy; microhardness measurements were also conducted. It was found that the commercial AZ91 alloy undergoes a cellular/dendritic transition during melt-spinning at a speed of 34 m/s. A strengthening effect due to aging was observed: a maximum hardness of 110 HV/0.05 and an age-hardenability of 50% were obtained when the ribbon was aged at 200 deg. C for 20 min. The β-Mg 17 Al 12 phase exhibits net and dispersion types of distribution during precipitation. The dispersion of precipitates in dendritic grains or cells is the main source of strengthening

High damping Al-Fe-Mo-Si/Zn-Al composites produced by rapidly solidified powder metallurgy process

International Nuclear Information System (INIS)

Li, P.Y.; Dai, S.L.; Chai, S.C.; Li, Y.R.

2000-01-01

The metallic materials commonly used in aircraft and aerospace fields, such as aluminum and titanium alloys, steels, etc., show extremely low damping capacity (usually of the order of or less than 10 -3 ). Thus, some problems related to vibration may emerge and influence the reliability, safety and life of airplanes, satellites, etc. It has been reported that almost two thirds of errors for rockets and satellites are related to vibration and noise. One effective way to solve these vibration-related problems is to adopt high damping metallic materials. Conventional high damping alloys exhibit damping capacity above 10 -2 , however, their densities are usually great than 5 x 10 3 kg m -3 , or their strengths are less than 200 MPa (for alloys based on dislocation damping), making them impossible to be applied to aircraft and aerospace areas. Recently, some low-density high-damping metal/metal composites based on aluminum and high damping alloys have been developed in Beijing Institute of Aeronautical Materials (BIAM) by the rapidly solidified power metallurgy process. This paper aims to report the properties of the composites based on a high temperature Al-Fe-Mo-Si alloy and a high damping Zn-Al alloy, and compare them with that of 2618-T61 alloy produced by the ingot metallurgy process

Disorder trapping in Ni3(Al, Ti) by solidification from the undercooled melt

International Nuclear Information System (INIS)

Goetzinger, R.; Kurz, W.

1997-01-01

Modelling of rapid solidification predicts disorder trapping in the superlattice structure of Ni 3 Al. However, experimental investigations on this compound suffer from ambiguities concerning the solidification path. There is a phase selection competition between the ordered fcc γ'-phase (Ni 3 Al), the ordered bcc β-phase (NiAl), the disordered fcc γ-phase (Ni), the stable γ'/β eutectic and the metastable γ/β eutectic, and there are subsequent solid state transformations. A replacement of several at.% Al by Ti leads to a stabilization of the γ'-phase and to an avoidance of most of the problems encountered on Ni 3 Al. The experiments on Ni 3 (Al, Ti) presented here clearly show the expected disordered crystallization from the undercooled melt. This was proven by measuring the dendrite growth velocity of electromagnetically levitated droplets and by analysing the data in the framework of dendrite and kinetic growth models. Complementary microstructural investigations were performed on the as-solidified samples. (orig.)

Fabrication of Intermetallic Titanium Alloy Based on Ti2AlNb by Rapid Quenching of Melt

Science.gov (United States)

Senkevich, K. S.; Serov, M. M.; Umarova, O. Z.

2017-11-01

The possibility of fabrication of rapidly quenched fibers from alloy Ti - 22Al - 27Nb by extracting a hanging melt drop is studied. The special features of the production of electrodes for spraying the fibers by sintering mechanically alloyed powdered components of the alloy, i.e., titanium hydride, niobium, and aluminum dust, are studied. The rapidly quenched fibers with homogeneous phase composition and fine-grained structure produced from alloy Ti - 22Al - 27Nb are suitable for manufacturing compact semiproducts by hot pressing.

Solidifier effectiveness : variation due to oil composition, oil thickness and temperature

International Nuclear Information System (INIS)

Fieldhouse, B.; Fingas, M.

2009-01-01

This paper provided an overview of solidifier types and composition. Solidifiers are a class of spill treating agents that offer an effective means to convert a liquid oil into a solid material. They are used as a treatment option for oil spills on water. This paper also reported on recent laboratory studies that consist of 4 components: (1) a qualitative examination of the characteristics of the interaction of a broad range of solidifier products with a standard oil to evaluate reaction rate, states of solidification, and the impact of dosage, (2) a comparison of a smaller subset of solidifiers on the standard oil at lower temperatures, (3) solidifier treatment on a range of oils of varying physical properties and composition to assess the potential scope of application, and (4) the treatment of a series of small-scale oil layers of varying thickness to determine the significance of oil thickness on solidifier effectiveness and recovery. This paper also reviewed solidifier chemistry with particular reference to polymer sorbents; cross-linking agents; and cross-linking agents and polymeric sorbents combined. Toxicity is also an important issue regarding solidifiers. The aquatic toxicity of solidifiers is low and not measurable as the products are not water-soluble. There have not been any studies on the effects of the solidifier or the treated oil on surface feeders and shoreline wildlife that may come into contact with the products. It was concluded that oil composition may play a major role in solidifier effectiveness. The effectiveness of solidifiers is also inhibited at reduced temperatures, increased viscosity and density of the oil. 25 refs., 5 tabs., 2 figs., 1 appendix

Phase Composition of a CrMo0.5NbTa0.5TiZr High Entropy Alloy: Comparison of Experimental and Simulated Data

OpenAIRE

Fan Zhang; Oleg N. Senkov; Jonathan D. Miller

2013-01-01

Microstructure and phase composition of a CrMo0.5NbTa0.5TiZr high entropy alloy were studied in the as-solidified and heat treated conditions. In the as-solidified condition, the alloy consisted of two disordered BCC phases and an ordered cubic Laves phase. The BCC1 phase solidified in the form of dendrites enriched with Mo, Ta and Nb, and its volume fraction was 42%. The BCC2 and Laves phases solidified by the eutectic-type reaction, and their volume fractions were 27% and 31%, respectively....

Microstructure and high temperature oxidation resistance of in-situ synthesized TiN/Ti{sub 3}Al intermetallic composite coatings on Ti6Al4V alloy by laser cladding process

Energy Technology Data Exchange (ETDEWEB)

Liu, Hongxi, E-mail: piiiliuhx@sina.com; Zhang, Xiaowei; Jiang, Yehua; Zhou, Rong

2016-06-15

High temperature anti-oxidation TiN/Ti{sub 3}Al intermetallic composite coatings were fabricated with the powder and AlN powder on Ti6Al4V titanium alloy surface by 6 kW transverse-flow CO{sub 2} laser apparatus. The chemical composition, morphology and microstructure of the TiN/Ti{sub 3}Al composite coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high temperature oxidation resistance of TiN/Ti{sub 3}Al coating, the isothermal oxidation test was performed in a high temperature resistance furnace at 600 °C and 800 °C, respectively. The result shows that the composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like or dendrites), with an even distribution in Ti{sub 3}Al matrix. It indicates that a physical and chemical reaction between Ti powder and AlN powder has completely occurred under the laser irradiation condition. In addition, the microhardness of the TiN/Ti3Al intermetallic composite coating is 3.4 times higher than that of the Ti6Al4V alloy substrate and reaches 844 HV{sub 0.2}. The high temperature oxidation behavior test reveals that the high temperature oxidation resistance of TiN/Ti{sub 3}Al composite coating is much better than that of titanium alloy substrate. The excellent high temperature oxidation resistance of TiN/Ti{sub 3}Al intermetallic composite coating is attributed to the formation of reinforced phases TiN, Al{sub 2}O{sub 3} and TiO{sub 2}. The laser cladding TiN/Ti{sub 3}Al intermetallic composite coating is anticipated to be a promising high temperature oxidation resistance coating for Ti6Al4V alloy. - Highlights: • In-situ TiN/Ti{sub 3}Al composite coating was synthesized on Ti6Al4V alloy by laser cladding. • The influence of Ti and AlN molar ratio on the microstructure of the coating was studied. • The TiN/Ti{sub 3}Al intermetallic

As-cast structure refinement of Ti-46Al alloy by hafnium and boron additions

Directory of Open Access Journals (Sweden)

Zhang Li

2009-05-01

Full Text Available The infl uence of Hf and B on the solidifi cation structure of cast Ti-46Al alloys was investigated. The results show that the coupling effect of Hf and B changes the solidifi cation structure morphology and strongly refi nes the grain size. When the Hf+B contents were increased from 0 + 0.0 to 3 + 0.2, 5 + 0.6 and 7 + 1.0 (in at. %, the solidification structure morphology changed from coarse columnar dendrite to fine columnar dendrite, then to equiaxed dendrite, and further to fi ne near granular grain whilst the average grain size decreased to 20 μm. It is concluded that the columnar dendrite refinement is due to the effect of Hf and B on the decrease of Al diffusion coeffi cient in the melt. The fi ne near granular grain formation is attributed to the combined constitutional supercooling formed by Al and B segregation that is strengthened by Hf and B additions at the solid/liquid interface during solidifi cation, and the TiB2 precipitates acting as heterogeneous nuclei

Effect of cooling rate and Mg addition on the structural evaluation of rapidly solidified Al-20wt%Cu-12wt%Fe alloy

Energy Technology Data Exchange (ETDEWEB)

Karaköse, Ercan, E-mail: ekarakose@karatekin.edu.tr [Çankırı Karatekin University, Faculty of Sciences, Department of Physics, 18100 Çankırı (Turkey); Çolak, Hakan [Çankırı Karatekin University, Faculty of Sciences, Department of Chemistry, 18100 Çankırı (Turkey)

2016-11-15

The present work examines the effect of Mg contents and cooling rate on the morphology and mechanical properties of Al{sub 20}Cu{sub 12}Fe quasicrystalline alloy. The microstructure of the alloys was analyzed by scanning electron microscopy and the phase composition was identified by X-ray diffractometry. The melting characteristics were studied by differential thermal analysis under an Ar atmosphere. The mechanical features of the melt-spun and conventionally solidified alloys were tested by tensile-strength test and Vickers micro-hardness test. It was found that the final microstructure of the Al{sub 20}Cu{sub 12}Fe samples mainly depends on the cooling rate and Mg contents, which suggests that different cooling rates and Mg contents produce different microstructures and properties. The average grain sizes of the melt spun samples were about 100–300 nm at 35 m/s. The nanosize, dispersed, different shaped quasicrystal particles possessed a remarkable effect to the mechanical characteristics of the rapidly solidified ribbons. The microhardness values of the melt spun samples were approximately 18% higher than those of the conventionally counterparts. - Highlights: •Quasicrystal-creating materials have high potential for applications. •Different shaped nanosize quasicrystal particles were observed. •The addition of Mg has an important impact on the mechanical properties. •H{sub V} values of the MS0, MS3 and MS5 samples at 35 m/s were 8.56, 8.66 and 8.80 GPa. •The volume fraction of IQC increases with increasing cooling rates.

Biodegradation testing of solidified low-level waste streams

International Nuclear Information System (INIS)

Piciulo, P.L.; Shea, C.E.; Barletta, R.E.

1985-05-01

The NRC Technical Position on Waste Form (TP) specifies that waste should be resistant to biodegradation. The methods recommended in the TP for testing resistance to fungi, ASTM G21, and for testing resistance to bacteria, ASTM G22, were carried out on several types of solidified simulated wastes, and the effect of microbial activity on the mechanical strength of the materials tested was examined. The tests are believed to be sufficient for distinguishing between materials that are susceptible to biodegradation and those that are not. It is concluded that failure of these tests should not be regarded of itself as an indication that the waste form will biodegrade to an extent that the form does not meet the stability requirements of 10 CFR Part 61. In the case of failure of ASTM G21 or ASTM G22 or both, it is recommended that additional data be supplied by the waste generator to demonstrate the resistance of the waste form to microbial degradation. To produce a data base on the applicability of the biodegradation tests, the following simulated laboratory-scale waste forms were prepared and tested: boric acid and sodium sulfate evaporator bottoms, mixed-bed bead resins and powdered resins each solidified in asphalt, cement, and vinyl ester-styrene. Cement solidified wastes supported neither fungal nor bacterial growth. Of the asphalt solidified wastes, only the forms of boric acid evaporator bottoms did not support fungal growth. Bacteria grew on all of the asphalt solidified wastes. Cleaning the surface of these waste forms did not affect bacterial growth and had a limited effect on the fungal growth. Only vinyl esterstyrene solidified sodium sulfate evaporator bottoms showed viable fungi cultures, but surface cleaning with solvents eliminated fungal growth in subsequent testing. Some forms of all the waste streams solidified in vinyl ester-styrene showed viable bacteria cultures. 13 refs., 12 tabs

Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part I. Microstructural Characterization of Rapidly Solidified Solders

Science.gov (United States)

Reeve, Kathlene N.; Choquette, Stephanie M.; Anderson, Iver E.; Handwerker, Carol A.

2016-12-01

Particles of Cu x Al y in Sn-Cu-Al solders have previously been shown to nucleate the Cu6Sn5 phase during solidification. In this study, the number and size of Cu6Sn5 nucleation sites were controlled through the particle size refinement of Cu x Al y via rapid solidification processing and controlled cooling in a differential scanning calorimeter. Cooling rates spanning eight orders of magnitude were used to refine the average Cu x Al y and Cu6Sn5 particle sizes down to submicron ranges. The average particle sizes, particle size distributions, and morphologies in the microstructures were analyzed as a function of alloy composition and cooling rate. Deep etching of the samples revealed the three-dimensional microstructures and illuminated the epitaxial and morphological relationships between the Cu x Al y and Cu6Sn5 phases. Transitions in the Cu6Sn5 particle morphologies from faceted rods to nonfaceted, equiaxed particles were observed as a function of both cooling rate and composition. Initial solidification cooling rates within the range of 103 to 104 °C/s were found to be optimal for realizing particle size refinement and maintaining the Cu x Al y /Cu6Sn5 nucleant relationship. In addition, little evidence of the formation or decomposition of the ternary- β phase in the solidified alloys was noted. Solidification pathways omitting the formation of the ternary- β phase agreed well with observed room temperature microstructures.

Rutile TiO{sub 2} active-channel thin-film transistor using rapid thermal annealing

Energy Technology Data Exchange (ETDEWEB)

Kim, Sung-Jin; Heo, Kwan-Jun; Yoo, Su-Chang; Choi, Seong-Gon [Chungbuk National University, Cheongju (Korea, Republic of); Chang, Seung-Wook [Samsung Display, Co., Ltd., Suwon (Korea, Republic of)

2014-10-15

TiO{sub 2} active-channel thin-film transistors (TFTs), in which the bottom-gate top-contact architecture was prepared with atomic layer deposition grown TiO{sub 2} as the semiconducting layer, were fabricated and then investigated based on key process parameters, such as the rapid thermal annealing (RTA) temperature. Structural analyses suggested that TiO{sub 2} films annealed at temperatures above 500 .deg. C changed from an amorphous to a rutile phase. The TFT with a TiO{sub 2} semiconductor annealed at 600 .deg. C exhibited strongly-saturated output characteristics, a much higher on/off current ratio of 4.3 x 10{sup 5}, and an electron mobility of 0.014 cm{sup 2}/Vs. Moreover, the potential for manipulating TiO{sub 2}-based TFTs with RTA methodology was demonstrated through the realization of a simple resistive-load inverter.

Solidified ceramics of radioactive wastes and method of producing it

International Nuclear Information System (INIS)

Oota, Takao; Matake, Shigeru; Ooka, Kazuo.

1980-01-01

Purpose: To provide solidified ceramics which have low leaching properties to water of radioactive substance, excellent heat dissipating and resistive properties and high mechanical strength by mixing and sintering limited amounts of titanium and aluminum compounds with calcined radioactive wastes containing special compound. Method: More than 20% by weight of titanium compound (as TiO 2 ) and more than 5% by weight of aluminum compound (as Al 2 O 3 ) are mixed with the calcined radioactive wasted containing, as converted by oxide, 5 to 40% by weight of Na 2 O, 5 to 20% by weight of Fe 2 O 3 , 5 to 15% by weight of MoO 3 , 5 to 15% by weight of ZrO 2 , 2 to 10% by weight of CeO 2 , 2 to 10% by weight of Cs 2 O, 1 to 5% by weight of BaO, 1 to 5% by weight of SrO, 0.2 to 2% by weight of Rb 2 O, 0.2% by weight of Y 2 O 3 , 0.2 to 2% by weight of NiO, 5 to 20% by weight of rare earth metal oxide, and 0.2 to 2% by weight of Cr 2 O 3 . The mixture is molded, sintered, and solidified to ceramics which contains no Mo phase, Na 2 O, MoO 3 , K 2 O, MoO 3 and Cs 2 O, MoO 3 phases and the like. (Yoshino, Y.)

Phase transformations in the rapidly solidified Ti{sub 40}Zr{sub 20}Hf{sub 20}Pd{sub 20} alloy

Energy Technology Data Exchange (ETDEWEB)

Chen, N. [Division of Engineering Materials, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Yao Kefu [Division of Engineering Materials, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)], E-mail: kfyao@tsinghua.edu.cn; Louzguine-Luzgin, D.V. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan); Qiu Shengbao [Division of Engineering Materials, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Ranganathan, S. [Department of Metallurgy, Indian Institute of Science, Bangalore 560 012 (India); Inoue, A. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

2007-10-15

We report that an approximant phase was initially obtained in amorphous Ti{sub 40}Zr{sub 20}Hf{sub 20}Pd{sub 20} alloy. In the initial stage of the devitrification process, the approximant phase transforms into an icosahedral (I) phase with a high thermal stability while the cF96 Zr{sub 2}Ni-type (space group Fd3-bar m with a=1.25nm and 96 atoms cell{sup -1}) particles precipitate from the amorphous matrix. Eventually the I phase grows to several hundred nanometers when annealed at about 1000K and then transforms into the Zr{sub 2}Ni-type phase with an endothermic reaction.

Variation of long-period stacking order structures in rapidly solidified Mg97Zn1Y2 alloy

International Nuclear Information System (INIS)

Matsuda, M.; Ii, S.; Kawamura, Y.; Ikuhara, Y.; Nishida, M.

2005-01-01

The long-period stacking order (LPSO) structures in rapidly solidified Mg 97 Zn 1 Y 2 alloy have been studied by conventional and high-resolution transmission electron microscopes (HRTEMs). There are four kinds of stacking sequences in the LPSO structures, i.e., 18R of ABABABCACACABCBCBC, 14H of ACBCBABABABCBC, 10H of ABACBCBCAB and 24R of ABABABABCACACACABCBCBCBC. The 18R structure is dominantly observed in the present study. The rest three are occasionally observed in places. The 10H and 24R structures are recently discovered. The lattice constants of 18R(1-bar 1-bar -bar 1-bar 1-bar -bar 2) 3 , 14H(2-bar -bar 1-bar 2-bar -bar 1-bar 1-bar -bar 1-bar 1-bar -bar 2-bar 1-bar -bar 2), 10H(1-bar 3-bar -bar 1-bar 1-bar -bar 3-bar 1-bar ) and 24R(1-bar 1-bar -bar 1-bar 1-bar -bar 1-bar 1-bar -bar 2) 3 structures are estimated to be a=0.320nm and c=4.678nm, a=0.325nm and c=3.694nm, a=0.325nm and c=2.603nm, a=0.322nm and c=6.181nm for the hexagonal structure, respectively

Energy asymmetry in melting and solidifying processes of PCM

International Nuclear Information System (INIS)

Jin, Xing; Hu, Huoyan; Shi, Xing; Zhang, Xiaosong

2015-01-01

Highlights: • The melting process and the solidifying process of PCM were asymmetrical. • The enthalpy and state of PCM were affected by its previous state. • The main reason for energy asymmetry of PCM was supercooling. - Abstract: The solidifying process of phase change material (PCM) was usually recognized as the exact inverse process of its melting process, especially when building the heat transfer model of PCM. To figure out that whether the melting process and the solidifying process of PCM were symmetrical, several kinds of PCMs were tested by a differential scanning calorimeter (DSC) in this paper. The experimental results showed that no matter using the DSC dynamic measurement method or the DSC step measurement method, the melting process and the solidifying process of PCM were asymmetrical. Because of the energy asymmetry in the melting and solidifying processes of PCM, it was also found that the enthalpy and the state of PCM were not only dependent on its temperature, but also affected by its “previous state”.

Microstructural characterization of a rapidly solidified ultrahigh strength Al94.5Cr3Co1.5Ce1 alloy

International Nuclear Information System (INIS)

Ping, D.H.; Hono, K.; Inoue, A.

2000-01-01

The microstructure of a rapidly solidified Al 94.5 Cr 3 Co 1.5 Ce 1 alloy has been examined in detail by means of high resolution transmission electron microscopy (HRTEM) and atom probe field ion microscopy (APFIM). In the as-quenched microstructure, nanoscale particles of a solute-enriched amorphous phase and an Al-Cr compound are dispersed in randomly oriented fine grains of α-Al ( 200nm ). The interface between the Al grains and the amorphous particles is not smooth but irregular with atomic protrusions and concavities, suggesting that interfacial instability occurs during the solidification process. Nanoscale amorphous particles are formed as a result of solute trapping within the rapidly grown Al grains. After annealing at 400 C for 15 minutes grain growth occurs, and the interface of the Al grains is smoothed. The amorphous region trapped within the grains if crystallized to an Al-Cr compound, but no icosahedral phase has been confirmed. The APFIM results have revealed that Cr and Ce atoms have a similar partitioning behavior, i.e., they are rejected from the α-Al phase and partitioned into the trapped amorphous regions. On the other hand, Co atoms are not partitioned between the two phases in the as-quenched state but are partitioned into the α-Al grains in the annealed alloys being rejected from the Al compounds and finally form Al-Co compounds. Based on these microstructural characterization results, the origins of high strength of this alloy are discussed

Rapidly solidified long-range-ordered alloys

International Nuclear Information System (INIS)

Lee, E.H.; Koch, C.C.; Liu, C.T.

1981-01-01

The influence of rapid solidification processing on the microstructure of long-range-ordered alloys in the (Fe, Co, Ni) 3 V system has been studied by transmission electron microscopy. The main microstructural feature of the as-quenched alloys was a fine cell structure (approx. 300 nm diameter) decorated with carbide particles. This structure was maintained aftr annealing treatments which develop the ordered crystal structure. Other features of the microstructures both before and after annealing are presented and discussed. 6 figures

Radioactive substance solidifying device

International Nuclear Information System (INIS)

Sakoda, Kotaro.

1979-01-01

Purpose: To easily solidify radioactive substances adhering to the surfaces of solid wastes without scattering in the circumference by paints, and further to reduce surface contamination concentrations. Constitution: Solid wastes are placed on a hanging plate, and dipped in paints within a paint dipping treatment tank installed at the lower part of a treatment tank by means of a monorail hoist, and the surfaces of said solid wastes are coated with paints, thereby to solidify the radioactivity on the surfaces of the solid wastes. After dipping, the solid wastes are suspended up to a paint spraying tank to dry the paints. After drying, non-contaminated paints are atomized to apply through an atomizing tube onto the solid wastes. After drying the atomized paints, the solid wastes are carried outside the treatment tank by means of the monorail hoist. (Yoshino, Y.)

Parameters of Solidifying Mixtures Transporting at Underground Ore Mining

Directory of Open Access Journals (Sweden)

Golik Vladimir

2017-01-01

Full Text Available The article is devoted to the problem of providing mining enterprises with solidifying filling mixtures at underground mining. The results of analytical studies using the data of foreign and domestic practice of solidifying mixtures delivery to stopes are given. On the basis of experimental practice the parameters of transportation of solidifying filling mixtures are given with an increase in their quality due to the effect of vibration in the pipeline. The mechanism of the delivery process and the procedure for determining the parameters of the forced oscillations of the pipeline, the characteristics of the transporting processes, the rigidity of the elastic elements of pipeline section supports and the magnitude of vibrator’ driving force are detailed. It is determined that the quality of solidifying filling mixtures can be increased due to the rational use of technical resources during the transportation of mixtures, and as a result the mixtures are characterized by a more even distribution of the aggregate. The algorithm for calculating the parameters of the pipe vibro-transport of solidifying filling mixtures can be in demand in the design of mineral deposits underground mining technology.

Parameters of Solidifying Mixtures Transporting at Underground Ore Mining

Science.gov (United States)

Golik, Vladimir; Dmitrak, Yury

2017-11-01

The article is devoted to the problem of providing mining enterprises with solidifying filling mixtures at underground mining. The results of analytical studies using the data of foreign and domestic practice of solidifying mixtures delivery to stopes are given. On the basis of experimental practice the parameters of transportation of solidifying filling mixtures are given with an increase in their quality due to the effect of vibration in the pipeline. The mechanism of the delivery process and the procedure for determining the parameters of the forced oscillations of the pipeline, the characteristics of the transporting processes, the rigidity of the elastic elements of pipeline section supports and the magnitude of vibrator' driving force are detailed. It is determined that the quality of solidifying filling mixtures can be increased due to the rational use of technical resources during the transportation of mixtures, and as a result the mixtures are characterized by a more even distribution of the aggregate. The algorithm for calculating the parameters of the pipe vibro-transport of solidifying filling mixtures can be in demand in the design of mineral deposits underground mining technology.

Effects of leachate concentration on the integrity of solidified clay liners.

Science.gov (United States)

Xue, Qiang; Zhang, Qian

2014-03-01

This study aimed to evaluate the impact of landfill leachate concentration on the degradation behaviour of solidified clay liners and to propose a viable mechanism for the observed degradation. The results indicated that the unconfined compressive strength of the solidified clay decreased significantly, while the hydraulic conductivity increased with the leachate concentration. The large pore proportion in the solidified clay increased and the sum of medium and micro pore proportions decreased, demonstrating that the effect on the solidified clay was evident after the degradation caused by exposure to landfill leachate. The unconfined compressive strength of the solidified clay decreased with increasing leachate concentration as the leachate changed the compact structure of the solidified clay, which are prone to deformation and fracture. The hydraulic conductivity and the large pore proportion of the solidified clay increased with the increase in leachate concentration. In contrast, the sum of medium and micro pore proportions showed an opposite trend in relation to leachate concentration, because the leachate gradually caused the medium and micro pores to form larger pores. Notably, higher leachate concentrations resulted in a much more distinctive variation in pore proportions. The hydraulic conductivity of the solidified clay was closely related to the size, distribution, and connection of pores. The proportion of the large pores showed a positive correlation with the increase of hydraulic conductivity, while the sum of the proportions of medium and micro pores showed a negative correlation.

Design of high-temperature high-strength Al-Ti-V-Zr alloys

International Nuclear Information System (INIS)

Lee, H.M.

1990-01-01

This paper reports that it seems plausible to develop high-strength Al-base alloys useful up to 698K in view of the behavior of nickel base superalloys which resist degradation of mechanical properties to 75 pct of their absolute melting temperature. For high temperature Al alloys, the dispersed hardening phase must not undergo phase transformation to an undesirable phase during long time exposure at the temperature of interest. An additional factor to be considered is the stability of the hardening phase with respect to Ostwald ripening. This coarsening resistance is necessary so that the required strength level can be maintained after the long-time service at high temperatures. The equilibrium crystal structures of Al 3 Ti, Al 3 V and Al 3 Zr are tetragonal D0 22 , D0 22 and D0 23 , respectively. At the temperatures of interest, around 698K, vanadium and titanium are mutually substitutable in the form of Al 3 (Ti, V). Much of titanium and vanadium can be substituted for zirconium in the D0 23 - type Al 3 Zr compound, creating Al 3 (Ti, Zr) and Al 3 (V, Zr), respectively. In particular, it has been reported that fcc L1 2 -structured Al 3 M dispersoids form in the rapidly solidified Al-V-Zr and Al-Ti-Zr systems and both L1 2 and D0 23 -structured Al 3 M phases showed slow coarsening kinetics

Method of solidifying radioactive wastes with plastics

International Nuclear Information System (INIS)

Matsuura, Hiroyuki; Yasumura, Keijiro; Minami, Yuji; Tomita, Toshihide

1980-01-01

Purpose: To prevent solidification of solidifying agents in the mixer by conducting the mixing process for the solidifying agents and the radioactive wastes at a temperature below the initiation point for the solidification of the agents thereby separating the mixing process from the solidification-integration process. Method: Catalyst such as cobalt naphthenate is charged into an unsaturated polyester resin in a mixer previously cooled, for example, to -10 0 C. They are well mixed with radioactive wastes and the mixture in the mixer is charged in a radioactive waste storage container. The temperature of the mixture, although kept at a low temperature initially, gradually increases to an ambient temperature whereby curing reaction is promoted and the reaction is completed about one day after to provide firm plastic solidification products. This can prevent the solidification of the solidifying agents in the mixer to thereby improve the circumstance's safety. (Kawakami, Y.)

Increased corrosion resistance of the AZ80 magnesium alloy by rapid solidification.

Science.gov (United States)

Aghion, E; Jan, L; Meshi, L; Goldman, J

2015-11-01

Magnesium (Mg) and Mg-alloys are being considered as implantable biometals. Despite their excellent biocompatibility and good mechanical properties, their rapid corrosion is a major impediment precluding their widespread acceptance as implantable biomaterials. Here, we investigate the potential for rapid solidification to increase the corrosion resistance of Mg alloys. To this end, the effect of rapid solidification on the environmental and stress corrosion behavior of the AZ80 Mg alloy vs. its conventionally cast counterpart was evaluated in simulated physiological electrolytes. The microstructural characteristics were examined by optical microscopy, SEM, TEM, and X-ray diffraction analysis. The corrosion behavior was evaluated by immersion, salt spraying, and potentiodynamic polarization. Stress corrosion resistance was assessed by Slow Strain Rate Testing. The results indicate that the corrosion resistance of rapidly solidified ribbons is significantly improved relative to the conventional cast alloy due to the increased Al content dissolved in the α-Mg matrix and the correspondingly reduced presence of the β-phase (Mg17 Al12 ). Unfortunately, extrusion consolidated solidified ribbons exhibited a substantial reduction in the environmental performance and stress corrosion resistance. This was mainly attributed to the detrimental effect of the extrusion process, which enriched the iron impurities and increased the internal stresses by imposing a higher dislocation density. In terms of immersion tests, the average corrosion rate of the rapidly solidified ribbons was <0.4 mm/year compared with ∼2 mm/year for the conventionally cast alloy and 26 mm/year for the rapidly solidified extruded ribbons. © 2014 Wiley Periodicals, Inc.

Constitution of the ternary system Cr–Ni–Ti

International Nuclear Information System (INIS)

Krendelsberger, Natalja; Weitzer, Franz; Du, Yong; Schuster, Julius C.

2013-01-01

Highlights: •Reaction scheme and liquidus surface for Cr-Ni-Ti are given. •In the ternary the C14-type Laves phase coexists with the liquid phase. •Two ternary eutectics are identified. -- Abstract: The nature of solid–liquid phase equilibria in the ternary system Cr–Ni–Ti was investigated using electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and differential thermal analysis. Literature data on solid state phase equilibria are confirmed. The Cr 2 Ti Laves phase modifications coexisting with Ni–Ti phases are clarified to be hexagonal C14-type and cubic C15-type. The C14-type Laves phase γCr 2 Ti is found to coexist with the liquid phase. It forms in the pseudobinary peritectic reaction p max1 from L + β(Cr,Ti) at 1389 °C. On further cooling γCr 2 Ti + NiTi solidify at 1202 °C in the pseudobinary eutectic e max2 . In the Cr-rich part of the system ternary eutectics occur at 1216 °C (E 1 : L = Ni 3 Ti + (Ni) + β(Cr,Ti)) and 1100 °C (E 2 : L = NiTi + Ni 3 Ti + β(Cr,Ti)), respectively. No ternary eutectic is found in the Ti-rich part. Rather the eutectic trough ends in the binary eutectic L = NiTi 2 + β(Ti)

Phase Composition of a CrMo0.5NbTa0.5TiZr High Entropy Alloy: Comparison of Experimental and Simulated Data

Directory of Open Access Journals (Sweden)

Fan Zhang

2013-09-01

Full Text Available Microstructure and phase composition of a CrMo0.5NbTa0.5TiZr high entropy alloy were studied in the as-solidified and heat treated conditions. In the as-solidified condition, the alloy consisted of two disordered BCC phases and an ordered cubic Laves phase. The BCC1 phase solidified in the form of dendrites enriched with Mo, Ta and Nb, and its volume fraction was 42%. The BCC2 and Laves phases solidified by the eutectic-type reaction, and their volume fractions were 27% and 31%, respectively. The BCC2 phase was enriched with Ti and Zr and the Laves phase was heavily enriched with Cr. After hot isostatic pressing at 1450 °C for 3 h, the BCC1 dendrites coagulated into round-shaped particles and their volume fraction increased to 67%. The volume fractions of the BCC2 and Laves phases decreased to 16% and 17%, respectively. After subsequent annealing at 1000 °C for 100 h, submicron-sized Laves particles precipitated inside the BCC1 phase, and the alloy consisted of 52% BCC1, 16% BCC2 and 32% Laves phases. Solidification and phase equilibrium simulations were conducted for the CrMo0.5NbTa0.5TiZr alloy using a thermodynamic database developed by CompuTherm LLC. Some discrepancies were found between the calculated and experimental results and the reasons for these discrepancies were discussed.

In vitro and in vivo performance of bioactive Ti6Al4V/TiC/HA implants fabricated by a rapid microwave sintering technique.

Science.gov (United States)

Choy, Man Tik; Tang, Chak Yin; Chen, Ling; Wong, Chi Tak; Tsui, Chi Pong

2014-09-01

Failure of the bone-implant interface in a joint prosthesis is a main cause of implant loosening. The introduction of a bioactive substance, hydroxyapatite (HA), to a metallic bone-implant may enhance its fixation on human bone by encouraging direct bone bonding. Ti6Al4V/TiC/HA composites with a reproducible porous structure (porosity of 27% and pore size of 6-89 μm) were successfully fabricated by a rapid microwave sintering technique. This method allows the biocomposites to be fabricated in a short period of time under ambient conditions. Ti6Al4V/TiC/HA composites exhibited a compressive strength of 93 MPa, compressive modulus of 2.9 GPa and microhardness of 556 HV which are close to those of the human cortical bone. The in vitro preosteoblast MC3T3-E1 cells cultured on the Ti6Al4V/TiC/HA composite showed that the composite surface could provide a biocompatible environment for cell adhesion, proliferation and differentiation without any cytotoxic effects. This is among the first attempts to study the in vivo performance of load-bearing Ti6Al4V/TiC and Ti6Al4V/TiC/HA composites in a live rabbit. The results indicated that the Ti6Al4V/TiC/HA composite had a better bone-implant interface compared with the Ti6Al4V/TiC implant. Based on the microstructural features, the mechanical properties, and the in vitro and in vivo test results from this study, the Ti6Al4V/TiC/HA composites have the potential to be employed in load-bearing orthopedic applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Microstructure of rapidly solidified Nb-based pre-alloyed powders for additive manufacturing

Energy Technology Data Exchange (ETDEWEB)

Guo, Yueling; Jia, Lina, E-mail: jialina@buaa.edu.cn; Kong, Bin; Zhang, Shengnan; Zhang, Fengxiang; Zhang, Hu

2017-07-01

Highlights: • Sphere shaped Nb-37Ti-13Cr-2Al-1Si pre-alloyed powders were prepared by PREP. • An oxide layer with a thickness of 9.39 nm was generated on the powder surface. • The main phases of the pre-alloyed powders were Nbss and Cr{sub 2}Nb. • SDAS increased and microhardness decreased with the increase of powder size. • Microstructure of powders evolved into large grains from dendrite structures after HT. - Abstract: For powder-based additive manufacturing, sphere-shaped Nb-37Ti-13Cr-2Al-1Si pre-alloyed powders were prepared by plasma rotating electrode processing (PREP). The microstructure, surface oxidation and microhardness of the pre-alloyed powders were systematically investigated. Results showed that the main phases were Nb solid solution (Nbss) and Cr{sub 2}Nb. The Cr{sub 2}Nb phases were further determined using transmission electron microscopy (TEM). Fine dendrite structures were observed in the as-fabricated pre-alloyed powders, which transformed to large grains after heat treatment (HT) at 1450 °C for 3 h. With the increase of powder size, the secondary dendrite arm spacing (SDAS) increased and the microhardness (HV) decreased. A clean powder surface free of oxide particles was obtained by PREP and an oxide layer with 9.39 nm in thickness was generated on the powder surface. Compared with Cr- and Nb-oxides, more Ti-oxides were formed on outmost powder surface with a higher content of Ti (up to 47.86 at.%). The differences upon the microstructure and microhardness of the pre-alloyed powders with different sizes were discussed.

Refining of cast intermetallic alloy Ti - 43 % Al - X (Nb, Mo, B) microstructure using heat treatment

International Nuclear Information System (INIS)

Imaev, R.M.; Imaev, V.M.; Khismatullin, T.G.

2006-01-01

The microstructure and high temperature mechanical properties are studied in a cast alloy Ti - 43 % Al - X (Nb, Mo, B) using methods of optical and scanning electron microscopy, X ray spectrum microanalysis and differential thermal analysis. The alloy belongs to a new class of β-solidifying γ-TiAl+α 2 -Ti 3 Al alloys. The alloy is investigated as cast and after heat treatment that promotes grain refinement. Mechanical properties are determined on tensile tests at 1000 and 1100 deg C in the air [ru

Microstructures and phase formation in rapidly solidified Sm-Fe alloys

International Nuclear Information System (INIS)

Shield, J.E.; Kappes, B.B.; Meacham, B.E.; Dennis, K.W.; Kramer, M.J.

2003-01-01

Sm-Fe-based alloys were produced by melt spinning with various melt spinning parameters and alloying additions. The structural and microstructural evolution varied and strongly depended on processing and alloy composition. The microstructural scale was found to vary from micron to nanometer scale depending on the solidification rate and alloying additions. Additions of Si, Ti, V, Zr and Nb with C were all found to refine the scale, and the degree of refinement was dependent on the atomic size of the alloying agent. The alloying was also found to affect the dynamical aspects of the melt spinning process, although in general the material is characterized by a poor melt stream and pool, which in part contributes to the microstructural variabilities. The alloying additions also suppressed the long-range ordering, leading to formation of the TbCu 7 -type structure. The ordering was recoverable upon heat treatment, although the presence of alloying agents suppressed the recovery process relative to the binary alloy. This was attributed to the presence of Ti (V, Nb, Zr) in solid solution, which limited the diffusion kinetics necessary for ordering. In the binary alloy, the ordering led to the development of antiphase domain structures, with the antiphase boundaries effectively pinning Bloch walls

In vitro and in vivo performance of bioactive Ti6Al4V/TiC/HA implants fabricated by a rapid microwave sintering technique

International Nuclear Information System (INIS)

Choy, Man Tik; Tang, Chak Yin; Chen, Ling; Wong, Chi Tak; Tsui, Chi Pong

2014-01-01

Failure of the bone–implant interface in a joint prosthesis is a main cause of implant loosening. The introduction of a bioactive substance, hydroxyapatite (HA), to a metallic bone–implant may enhance its fixation on human bone by encouraging direct bone bonding. Ti6Al4V/TiC/HA composites with a reproducible porous structure (porosity of 27% and pore size of 6–89 μm) were successfully fabricated by a rapid microwave sintering technique. This method allows the biocomposites to be fabricated in a short period of time under ambient conditions. Ti6Al4V/TiC/HA composites exhibited a compressive strength of 93 MPa, compressive modulus of 2.9 GPa and microhardness of 556 HV which are close to those of the human cortical bone. The in vitro preosteoblast MC3T3-E1 cells cultured on the Ti6Al4V/TiC/HA composite showed that the composite surface could provide a biocompatible environment for cell adhesion, proliferation and differentiation without any cytotoxic effects. This is among the first attempts to study the in vivo performance of load-bearing Ti6Al4V/TiC and Ti6Al4V/TiC/HA composites in a live rabbit. The results indicated that the Ti6Al4V/TiC/HA composite had a better bone–implant interface compared with the Ti6Al4V/TiC implant. Based on the microstructural features, the mechanical properties, and the in vitro and in vivo test results from this study, the Ti6Al4V/TiC/HA composites have the potential to be employed in load-bearing orthopedic applications. - Highlights: • Ti6Al4V/TiC and Ti6Al4V/TiC/HA composites were fabricated by microwave sintering. • Ti6Al4V/TiC/HA exhibited mechanical properties close to human cortical bone. • Ti6Al4V/TiC/HA could provide a biocompatible environment for bone cell growth. • Ti6Al4V/TiC/HA showed a better bone–implant interface than Ti6Al4V/TiC. • Ti6Al4V/TiC/HA could be used for bone replacement under load-bearing conditions

Microstructure, biocorrosion and cytotoxicity evaluations of rapid solidified Mg-3Ca alloy ribbons as a biodegradable material.

Science.gov (United States)

Gu, X N; Li, X L; Zhou, W R; Cheng, Y; Zheng, Y F

2010-06-01

Rapidly solidified (RS) Mg–3Ca alloy ribbons were prepared by the melt-spinning technique at different wheel rotating speeds (15 m s(-1), 30 m s(-1) and 45 m s(-1) with the as-cast Mg–3Ca alloy ingot as a raw material. The RS45 Mg–3Ca alloy ribbon showed a much more fine grain size feature (approximately 200–500 nm) in comparison to the coarse grain size (50–100 μm)of the original as-cast Mg–3Ca alloy ingot. The corrosion electrochemical tests in simulated body fluid indicated that the corrosion rate of the as-cast Mg–3Ca alloy was strongly reduced by the RS procedure and tended to be further decreased with increasing wheel rotating speeds(1.43 mm yr(-1) for RS15, 0.94 mm yr(-1) for RS30 and 0.36 mm yr(-1) for RS45). The RS Mg–3Ca alloy ribbons showed more uniform corrosion morphology compared with the as-cast Mg–3Ca alloy after polarization. The cytotoxicity evaluation revealed that the three experimental as-spun Mg–3Ca alloy ribbon extracts did not induce toxicity to the L-929 cells,whereas the as-cast Mg–3Ca alloy ingot extract did. The L-929 cells showed more improved adhesion on the surfaces of the three as-spun Mg–3Ca alloy ribbons than that of the as-cast Mg–3Ca alloy ingot.

Microstructure, biocorrosion and cytotoxicity evaluations of rapid solidified Mg-3Ca alloy ribbons as a biodegradable material

International Nuclear Information System (INIS)

Gu, X N; Zhou, W R; Zheng, Y F; Li, X L; Cheng, Y

2010-01-01

Rapidly solidified (RS) Mg-3Ca alloy ribbons were prepared by the melt-spinning technique at different wheel rotating speeds (15 m s -1 , 30 m s -1 and 45 m s -1 ) with the as-cast Mg-3Ca alloy ingot as a raw material. The RS45 Mg-3Ca alloy ribbon showed a much more fine grain size feature (approximately 200-500 nm) in comparison to the coarse grain size (50-100 μm) of the original as-cast Mg-3Ca alloy ingot. The corrosion electrochemical tests in simulated body fluid indicated that the corrosion rate of the as-cast Mg-3Ca alloy was strongly reduced by the RS procedure and tended to be further decreased with increasing wheel rotating speeds (1.43 mm yr -1 for RS15, 0.94 mm yr -1 for RS30 and 0.36 mm yr -1 for RS45). The RS Mg-3Ca alloy ribbons showed more uniform corrosion morphology compared with the as-cast Mg-3Ca alloy after polarization. The cytotoxicity evaluation revealed that the three experimental as-spun Mg-3Ca alloy ribbon extracts did not induce toxicity to the L-929 cells, whereas the as-cast Mg-3Ca alloy ingot extract did. The L-929 cells showed more improved adhesion on the surfaces of the three as-spun Mg-3Ca alloy ribbons than that of the as-cast Mg-3Ca alloy ingot.

The TiO2 Refraction Film for CsI Scintillator

OpenAIRE

C. C. Chen; C. W. Hun; C. J. Wang; C. Y. Chen; J. S. Lin; K. J. Huang

2015-01-01

Cesium iodide (CsI) melt was injected into anodic aluminum oxide (AAO) template and was solidified to CsI column. The controllable AAO channel size (10~500 nm) can makes CsI column size from 10 to 500 nm in diameter. In order to have a shorter light irradiate from each singe CsI column top to bottom the AAO template was coated a TiO2 nano-film. The TiO2 film acts a refraction film and makes X-ray has a shorter irradiation path in the CsI crystal making a stronger the photo-electron signal. Wh...

Light-weight alloys for aerospace applications II; Proceedings of the 2nd Symposium, New Orleans, LA, Feb. 17-21, 1991

International Nuclear Information System (INIS)

Lee, E.W.; Kim, N.J.

1991-01-01

The present symposium on applications of light-weight alloys for aerospace discusses Al-Li alloys, aluminum alloys, advanced composites, and light alloys. Attention is given to Al-Li alloy development for parts made from thick plates, the structure and properties of P/M-aluminum alloys, X-ray rocking curve analysis of aging and deformation characteristics in Al-Li alloys, and the transformation characteristics of the 2090 Al-Li alloy. Topics considered include microstructural development in a rapidly solidified Al-Fe-V-Si alloy, the structure and mechanical properties of rapidly solidified Al-Cr-Hf alloys, the deformation mechanisms in superplastic Al-Mg alloys by microtexture technique, and the design of powder metallurgy aluminum alloys. Also discussed are the mechanical properties of monolithic and particular composites of L1(2) forms of Al3Ti, in situ polymer fiber-reinforced hybrid materials, thermal cycling of Ti-1421/SiC metal matrix composites, and the fracture behavior of a Ti3-Al-Nb alloy

Method of solidifying radioactive wastes

International Nuclear Information System (INIS)

Fukazawa, Tetsuo; Ootsuka, Masaharu; Uetake, Naoto; Ozawa, Yoshihiro.

1984-01-01

Purpose: To prepare radioactive solidified wastes excellent in strength, heat resistance, weather-proof, water resistance, dampproof and low-leaching property. Method: A hardening material reactive with alkali silicates to form less soluble salts is used as a hardener for alkali silicates which are solidification filler for the radioactive wastes, and mixed with cement as a water absorbent and water to solidify the radioactive wastes. The hardening agent includes, for example, CaCO 3 , Ca(ClO 4 ) 2 , CaSiF 6 and CaSiO 3 . Further, in order to reduce the water content in the wastes and reduce the gap ratio in the solidification products, the hardener adding rate, cement adding rate and water content are selected adequately. As the result, solidification products can be prepared with no deposition of easily soluble salts to the surface thereof, with extremely low leaching of radioactive nucleides. (Kamimura, M.)

Microstructure and wear of in-situ Ti/(TiN + TiB) hybrid composite layers produced using liquid phase process

Energy Technology Data Exchange (ETDEWEB)

Yazdi, R., E-mail: ryazdi@ut.ac.ir; Kashani-Bozorg, S.F.

2015-02-15

Tungsten inert gas (TIG) technique was conducted on commercially pure (CP)-Ti substrate, which was coated with h-BN-based powder mixture prior to the treatment. The treated surfaces were evaluated and characterized by means of scanning electron microscope (SEM), X-ray diffraction analysis, and electron dispersive spectrometry (EDS). The microhardness and wear experiment were also performed by using a microhardness machine and pin-on-disk tribometer. As h-BN reacted with titanium, an in-situ hybrid composite layer was formed showing near stoichiometric dendrites of TiN, platelets of TiB and interdendritic regions of α′-Ti martensite crystal structures. The population level of TiN and TiB regions were found to increase using a pre-placed powder mixture with greater h-BN content. However, the fabricated layers exhibited cracking and porosity; these were minimized by adjusting arc energy density and h-BN content of powder mixture. The microhardness value of the fabricated hybrid composite layers was found to be in the range of ∼650 HV{sub 0.2}–1000 HV{sub 0.2}; this is three to five times higher than that of the untreated CP-Ti substrate. In addition, the in-situ hybrid composite layers exhibited superior wear behavior over CP-Ti substrate; this is attributed to the formation of newly formed ceramic phases in the solidified surface layers and good coherent interface between the composite layer and CP-substrate. Meanwhile, severe adhesive wear mechanism of CP-titanium surface changed to mild abrasive one as a result of surface treatment. - Highlights: • In-situ Ti/(TiN + TiB) hybrid composite layers were synthesized by TIG processing on commercially pure titanium. • The microstructure features were characterized by several methods. • Microhardness enhanced three to five times higher than that of the CP-Ti substrate after surface modification. • The fabricated composite layers improved wear resistance of CP-titanium. • Severe adhesive wear mechanism of

Copper-base alloys processed by rapid solidification and ion implantation

International Nuclear Information System (INIS)

Wood, J.V.; Elvidge, C.J.; Johnson, E.; Johansen, A.; Sarholt-Kristensen, L.; Henriksen, O.

1985-01-01

Alloys of Cu-Sn and Cu-B have been processed by both melt spinning and ion implantation. In some instances (e.g. Cu-Sn alloys) rapidly solidified ribbons have been subjected to further implantation. This paper describes the similarities and differences in structure of materials subjected to a dynamic and contained process. For example in Cu-B alloys (up to 2wt% Boron) extended solubility is found in implanted alloys which is not present to the same degree in rapidly solidified alloys of the same composition. Likewise the range and nature of the reversible martensitic transformation is different in both cases as examined by electron microscopy and differential scanning calorimetry. (orig.)

Incorporating an extended dendritic growth model into the CAFE model for rapidly solidified non-dilute alloys

International Nuclear Information System (INIS)

Ma, Jie; Wang, Bo; Zhao, Shunli; Wu, Guangxin; Zhang, Jieyu; Yang, Zhiliang

2016-01-01

We have extended the dendritic growth model first proposed by Boettinger, Coriell and Trivedi (here termed EBCT) for microstructure simulations of rapidly solidified non-dilute alloys. The temperature-dependent distribution coefficient, obtained from calculations of phase equilibria, and the continuous growth model (CGM) were adopted in the present EBCT model to describe the solute trapping behaviors. The temperature dependence of the physical properties, which were not used in previous dendritic growth models, were also considered in the present EBCT model. These extensions allow the present EBCT model to be used for microstructure simulations of non-dilute alloys. The comparison of the present EBCT model with the BCT model proves that the considerations of the distribution coefficient and physical properties are necessary for microstructure simulations, especially for small particles with high undercoolings. Finally, the EBCT model was incorporated into the cellular automaton-finite element (CAFE) model to simulate microstructures of gas-atomized ASP30 high speed steel particles that were then compared with experimental results. Both the simulated and experimental results reveal that a columnar dendritic microstructure preferentially forms in small particles and an equiaxed microstructure forms otherwise. The applications of the present EBCT model provide a convenient way to predict the microstructure of non-dilute alloys. - Highlights: • A dendritic growth model was developed considering non-equilibrium distribution coefficient. • The physical properties with temperature dependence were considered in the extended model. • The extended model can be used to non-dilute alloys and the extensions are necessary in small particles. • Microstructure of ASP30 steel was investigated using the present model and verified by experiment.

Incorporating an extended dendritic growth model into the CAFE model for rapidly solidified non-dilute alloys

Energy Technology Data Exchange (ETDEWEB)

Ma, Jie; Wang, Bo [State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200072 (China); Shanghai Engineering Technology Research Center of Special Casting, Shanghai 201605 (China); Zhao, Shunli [Research Institute, Baoshan Iron & Steel Co., Ltd, Shanghai 201900 (China); Wu, Guangxin [State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200072 (China); Shanghai Engineering Technology Research Center of Special Casting, Shanghai 201605 (China); Zhang, Jieyu, E-mail: zjy6162@staff.shu.edu.cn [State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200072 (China); Shanghai Engineering Technology Research Center of Special Casting, Shanghai 201605 (China); Yang, Zhiliang [State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200072 (China); Shanghai Engineering Technology Research Center of Special Casting, Shanghai 201605 (China)

2016-05-25

We have extended the dendritic growth model first proposed by Boettinger, Coriell and Trivedi (here termed EBCT) for microstructure simulations of rapidly solidified non-dilute alloys. The temperature-dependent distribution coefficient, obtained from calculations of phase equilibria, and the continuous growth model (CGM) were adopted in the present EBCT model to describe the solute trapping behaviors. The temperature dependence of the physical properties, which were not used in previous dendritic growth models, were also considered in the present EBCT model. These extensions allow the present EBCT model to be used for microstructure simulations of non-dilute alloys. The comparison of the present EBCT model with the BCT model proves that the considerations of the distribution coefficient and physical properties are necessary for microstructure simulations, especially for small particles with high undercoolings. Finally, the EBCT model was incorporated into the cellular automaton-finite element (CAFE) model to simulate microstructures of gas-atomized ASP30 high speed steel particles that were then compared with experimental results. Both the simulated and experimental results reveal that a columnar dendritic microstructure preferentially forms in small particles and an equiaxed microstructure forms otherwise. The applications of the present EBCT model provide a convenient way to predict the microstructure of non-dilute alloys. - Highlights: • A dendritic growth model was developed considering non-equilibrium distribution coefficient. • The physical properties with temperature dependence were considered in the extended model. • The extended model can be used to non-dilute alloys and the extensions are necessary in small particles. • Microstructure of ASP30 steel was investigated using the present model and verified by experiment.

The relationship between viscosity and refinement efficiency of pure aluminum by Al-Ti-B refiner

Energy Technology Data Exchange (ETDEWEB)

Yu Lina [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China)]. E-mail: xfliu@sdu.edu.cn

2006-11-30

The relationship between viscosity and refinement efficiency of pure aluminum with the addition of Al-Ti-B master alloy was studied in this paper. The experimental results show that when the grain size of solidified sample is finer the viscosity of the melt is higher after the addition of different Al-Ti-B master alloys. This indicates that viscosity can be used to approximately estimate the refinement efficiency of Al-Ti-B refiners in production to a certain extent. The main reason was also discussed in this paper by using transmission electron microscopy (TEM) analysis and differential scanning calorimetry (DSC) experiment.

Method of solidifying and disposing radioactive waste plastic

International Nuclear Information System (INIS)

Matsuura, Hiroyuki; Yasumura, Keijiro

1981-01-01

Purpose: To solidify radioactive waste as it is with plastic by forming a W/O (Water-in-Oil) emulsion with the radioactive waste and a plastic solidifier, and treating it with a polymerization starting agent, an accelerator, and the like. Method: A predetermined amount of alkaline substance such as sodium hydroxide, triethanol, or the like is added quantitatively to radioactive waste and it is mixed by an agitator. A predetermined amount of solidifier such as unsaturated polyester or the like is added to the mixture and it is further mixed by the agitator to form a stable W/O emulsion. Subsequently, predetermined amounts of polymerization starting agent such as methyl ethyl ketone peroxide and polymerization accelerator such as cobalt naphthenate or the like are added thereto, the mixture is mixed, and is then allowed to stand for at room temperature for the plastic solidification thereof. No reaction occurs after the solidification. (Sekiya, K.)

Processing and Characterization of Liquid-Phase Sintered NiTi Woven Structures

Science.gov (United States)

Erdeniz, Dinc; Weidinger, Ryan P.; Sharp, Keith W.; Dunand, David C.

2018-03-01

Porous NiTi is of interest for bone implants because of its unique combination of biocompatibility (encouraging osseointegration), high strength (to prevent fracture), low stiffness (to reduce stress shielding), and shape memory or superelasticity (to deploy an implant). A promising method for creating NiTi structures with regular open channels is via 3D weaving of NiTi wires. This paper presents a processing method to bond woven NiTi wire structures at contact points between wires to achieve structural integrity: (i) a slurry consisting of a blend of NiTi and Nb powders is deposited on the surface of the NiTi wires after the weaving operation; (ii) the powders are melted to create a eutectic liquid phase which collects at contact points; and (iii) the liquid is solidified and binds the NiTi woven structures. The bonded NiTi wire structures exhibited lower transformation temperatures compared to the as-woven NiTi wires because of Nb diffusion into the NiTi wires. A bonded woven sample was deformed in bending and showed near-complete recovery up to 6% strain and recovered nearly half of the deformation up to 19% strain.

Microstructure, biocorrosion and cytotoxicity evaluations of rapid solidified Mg-3Ca alloy ribbons as a biodegradable material

Energy Technology Data Exchange (ETDEWEB)

Gu, X N; Zhou, W R; Zheng, Y F [State Key Laboratory for Turbulence and Complex System and Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Li, X L [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Cheng, Y, E-mail: yfzheng@pku.edu.c [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China)

2010-06-01

Rapidly solidified (RS) Mg-3Ca alloy ribbons were prepared by the melt-spinning technique at different wheel rotating speeds (15 m s{sup -1}, 30 m s{sup -1} and 45 m s{sup -1}) with the as-cast Mg-3Ca alloy ingot as a raw material. The RS45 Mg-3Ca alloy ribbon showed a much more fine grain size feature (approximately 200-500 nm) in comparison to the coarse grain size (50-100 {mu}m) of the original as-cast Mg-3Ca alloy ingot. The corrosion electrochemical tests in simulated body fluid indicated that the corrosion rate of the as-cast Mg-3Ca alloy was strongly reduced by the RS procedure and tended to be further decreased with increasing wheel rotating speeds (1.43 mm yr{sup -1} for RS15, 0.94 mm yr{sup -1} for RS30 and 0.36 mm yr{sup -1} for RS45). The RS Mg-3Ca alloy ribbons showed more uniform corrosion morphology compared with the as-cast Mg-3Ca alloy after polarization. The cytotoxicity evaluation revealed that the three experimental as-spun Mg-3Ca alloy ribbon extracts did not induce toxicity to the L-929 cells, whereas the as-cast Mg-3Ca alloy ingot extract did. The L-929 cells showed more improved adhesion on the surfaces of the three as-spun Mg-3Ca alloy ribbons than that of the as-cast Mg-3Ca alloy ingot.

Simple and rapid determination methods for low-level radioactive wastes generated from nuclear research facilities. Guidelines for determination of radioactive waste samples

International Nuclear Information System (INIS)

Kameo, Yutaka; Shimada, Asako; Ishimori, Ken-ichiro; Haraga, Tomoko; Katayama, Atsushi; Nakashima, Mikio; Hoshi, Akiko

2009-10-01

Analytical methods were developed for simple and rapid determination of U, Th, and several nuclides, which are selected as important nuclides for safety assessment of disposal of wastes generated from research facilities at Nuclear Science Research Institute and Oarai Research and Development Center. The present analytical methods were assumed to apply to solidified products made from miscellaneous wastes by plasma melting in the Advanced Volume Reduction Facilities. In order to establish a system to analyze the important nuclides in the solidified products at low cost and routinely, we have advanced the development of a high-efficiency non-destructive measurement technique for γ-ray emitting nuclides, simple and rapid methods for pretreatment of solidified product samples and subsequent radiochemical separations, and rapid determination methods for long-lived nuclides. In the present paper, we summarized the methods developed as guidelines for determination of radionuclides in the low-level solidified products. (author)

Evaluation of solidified high-level waste forms

International Nuclear Information System (INIS)

1981-01-01

One of the objectives of the IAEA waste management programme is to coordinate and promote development of improved technology for the safe management of radioactive wastes. The Agency accomplished this objective specifically through sponsoring Coordinated Research Programmes on the ''Evaluation of Solidified High Level Waste Products'' in 1977. The primary objectives of this programme are to review and disseminate information on the properties of solidified high-level waste forms, to provide a mechanism for analysis and comparison of results from different institutes, and to help coordinate future plans and actions. This report is a summary compilation of the key information disseminated at the second meeting of this programme

Rapid fabrication of TiO2@carboxymethyl cellulose coatings capable of shielding UV, antifog and delaying support aging.

Science.gov (United States)

Li, Xiaozhou; Lv, Junping; Li, Dehuai; Wang, Lin

2017-08-01

Agricultural plastic films capable of shielding UV, filtering visible light and antifog are important to prolong their life and protect safeties of agriculturists and crops. In this work, high stable and small size TiO 2 @polymer nanoparticles (NPs) were prepared by an efficient one-pot microwave synthesis using titanic sulfate as Ti resource, carboxymethyl cellulose sodium (CMC) as complexing agent and stabilizer. The TiO 2 @CMC NPs obtained were then utilized to fabricate poly(ethylene imine) (PEI)/TiO 2 @CMC coatings on the surface of polypropylene films by a layer-by-layer assembly technique. The TiO 2 @CMC NPs show rapid deposition rate because small, spherical and anion-rich TiO 2 @CMC NPs possess large specific surface area and fast diffusion rate. More importantly, property experiments confirm that (PEI/TiO 2 @CMC)*15 coatings can not only effectively shield UV rays, filter visible light and prevent fogging but also delay the aging of their supports. Copyright © 2017 Elsevier Ltd. All rights reserved.

Surface modification induced phase transformation and structure variation on the rapidly solidified recast layer of titanium

Energy Technology Data Exchange (ETDEWEB)

Tsai, Ming-Hung [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Haung, Chiung-Fang [School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Division of Family and Operative Dentistry, Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan (China); Shyu, Shih-Shiun [Department of Dentistry, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City 231, Taiwan (China); Chou, Yen-Ru [Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan (China); Graduate Institute of Biomedical Materials and Tissue Engineering, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China); Lin, Ming-Hong [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); Peng, Pei-Wen, E-mail: apon@tmu.edu.tw [School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); and others

2015-08-15

In this study, neodymium-doped yttrium orthovanadate (Nd:YVO{sub 4}) as a laser source with different scanning speeds was used on biomedical Ti surface. The microstructural and biological properties of laser-modified samples were investigated by means of optical microscope, electron microscope, X-ray diffraction, surface roughness instrument, contact angle and cell cytotoxicity assay. After laser modification, the rough volcano-like recast layer with micro-/nanoporous structure and wave-like recast layer with nanoporous structure were generated on the surfaces of laser-modified samples, respectively. It was also found out that, an α → (α + rutile-TiO{sub 2}) phase transition occurred on the recast layers of laser-modified samples. The Ti surface becomes hydrophilic at a high speed laser scanning. Moreover, the cell cytotoxicity assay demonstrated that laser-modified samples did not influence the cell adhesion and proliferation behaviors of osteoblast (MG-63) cell. The laser with 50 mm/s scanning speed induced formation of rough volcano-like recast layer accompanied with micro-/nanoporous structure, which can promote cell adhesion and proliferation of MG-63 cell on Ti surface. The results indicated that the laser treatment was a potential technology to enhance the biocompatibility for titanium. - Highlights: • Laser induced the formation of recast layer with micro-/nanoporous structure on Ti. • An α → (α + rutile-TiO{sub 2}) phase transition was observed within the recast layer. • The Ti surface becomes hydrophilic at a high speed laser scanning. • Laser-modified samples exhibit good biocompatibility to osteoblast (MG-63) cell.

Particle Trapping and Banding in Rapid Colloidal Solidification

KAUST Repository

Elliott, J. A. W.

2011-10-11

We derive an expression for the nonequilibrium segregation coefficient of colloidal particles near a moving solid-liquid interface. The resulting kinetic phase diagram has applications for the rapid solidification of clay soils, gels, and related colloidal systems. We use it to explain the formation of bandlike defects in rapidly solidified alumina suspensions. © 2011 American Physical Society.

Method for solidifying powdery radioactive wastes

International Nuclear Information System (INIS)

Yasumura, Keijiro; Matsuura, Hiroyuki; Tomita, Toshihide.

1978-01-01

Purpose: To solidify powdery radioactive wastes through polymerization in a vessel at a high impregnation speed with no cloggings in pipes. Method: A drum can is lined with an inner liner layer of a predetermined thickness made of inflammable material such as glass fiber. A plurality of pipes for supplying liquid plastic monomer are provided in adjacent to the upper end face of the inflammable material or inserted between the vessel and the inflammable material. Then powdery radioactive wastes are filled in the vessel and the liquid plastic monomer dissolving therein a polymerization initiator is supplied through the pipes. The liquid plastic monomer impregnates through the inflammable material layer into the radioactive wastes and the plastic monomer is polymerized by the aid of the polymerization initiator after a predetermined of time to produce solidified plastic products of radioactive wastes. (Seki, T.)

Rapid and efficient photocatalytic reduction of hexavalent chromium by using “water dispersible” TiO2 nanoparticles

International Nuclear Information System (INIS)

Wang, Lei; Kang, Shi-Zhao; Li, Xiangqing; Qin, Lixia; Yan, Hao; Mu, Jin

2016-01-01

In the present work, “water dispersible” TiO 2 nanoparticles were prepared, and meanwhile, their photocatalytic activity was systematically tested for the reduction of aqueous Cr(VI) ions. It is found that the as-prepared “water dispersible” TiO 2 nanoparticles are a highly efficient photocatalyst for the reduction of Cr(VI) ions in water under UV irradiation, and suitable for the remediation of Cr(VI) ions wastewater with low concentration. Compared with commercial TiO 2 nanoparticles (P25), the “water dispersible” TiO 2 nanoparticles exhibit 3.8-fold higher photocatalytic activity. 100% Cr (VI) ions can be reduced into Cr(III) ions within 10 min when the Cr (VI) ions initial concentration is 10 mg L −1 . Moreover, the electrical energy consumption can be obviously decreased using the “water dispersible” TiO 2 nanoparticles. These results suggest that the “water dispersible” TiO 2 nanoparticles are a promising photocatalyst for rapid removal of Cr (VI) in environmental therapy. - Highlights: • “Water dispersible” TiO 2 nanoparticles with high photocatalytic activity. • 100% Cr (VI) (10 mg L −1 ) can be reduced within 10 min. • Obvious decrease of electrical energy consumption.

AE Monitoring of Diamond Turned Rapidly Soldified Aluminium 443

International Nuclear Information System (INIS)

Onwuka, G; Abou-El-Hossein, K; Mkoko, Z

2017-01-01

The fast replacement of conventional aluminium with rapidly solidified aluminium alloys has become a noticeable trend in the current manufacturing industries involved in the production of optics and optical molding inserts. This is as a result of the improved performance and durability of rapidly solidified aluminium alloys when compared to conventional aluminium. Melt spinning process is vital for manufacturing rapidly solidified aluminium alloys like RSA 905, RSA 6061 and RSA 443 which are common in the industries today. RSA 443 is a newly developed alloy with few research findings and huge research potential. There is no available literature focused on monitoring the machining of RSA 443 alloys. In this research, Acoustic Emission sensing technique was applied to monitor the single point diamond turning of RSA 443 on an ultrahigh precision lathe machine. The machining process was carried out after careful selection of feed, speed and depths of cut. The monitoring process was achieved with a high sampling data acquisition system using different tools while concurrent measurement of the surface roughness and tool wear were initiated after covering a total feed distance of 13km. An increasing trend of raw AE spikes and peak to peak signal were observed with an increase in the surface roughness and tool wear values. Hence, acoustic emission sensing technique proves to be an effective monitoring method for the machining of RSA 443 alloy. (paper)

Investigation on microstructure characterization and property of rapidly solidified Mg-Zn-Ca-Ce-La alloys

Energy Technology Data Exchange (ETDEWEB)

Zhou Tao, E-mail: tzhou1118@163.com [College of Material Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China); Chen Zhenhua, E-mail: chenzhenhua45@hotmail.com [College of Material Science and Engineering, Hunan University, Changsha 410082 (China); Yang Mingbo, E-mail: yangmingbo@cqit.edu.cn [College of Material Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China); Hu Jianjun, E-mail: hujj@qq.com [College of Material Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China); Xia Hua, E-mail: xiahua@cqut.edu.cn [College of Material Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China)

2012-01-15

Rapidly solidified (RS) Mg-Zn-Ca-Ce-La (wt.%) alloys have been produced via atomizing the alloy melt and subsequent splat-quenching on the water-cooled copper twin-rollers in the form of flakes. Microstructure characterization, phase compositions and thermal stability of the alloys have been systematically investigated. The results showed that with addition of RE (Ce and La) to the Mg-6Zn-5Ca alloy, the stable intermetallic compounds i.e. the Mg{sub x}Zn{sub y}RE{sub z} phase with a few Ca (about 3 at.%), shortened as the T Prime phase, were formed at the expense of the binary Mg-Zn and Ca{sub 2}Mg{sub 6}Zn{sub 3} phases, which was possibly beneficial to the enhanced thermal stability of the alloy. In the Mg-6Zn-5Ca-3Ce-0.5La alloy, the composition of the T Prime phase in the grain interior was different from that at the grain boundaries, in which the segregation of the La elements was found, and the atomic percentage ratio of Zn to Ce in the T Prime phase within the grains was close to 2. Moreover, the stable Mg{sub 2}Ca phases were detected around the T Prime phases at the grain boundaries in the alloy. - Research Highlights: Black-Right-Pointing-Pointer The phase constitution of RS Mg-6Zn-5Ca alloy can be improved by RE additions. Black-Right-Pointing-Pointer In the Mg-Zn-Ca-Ce-La alloys, the Mg{sub x}Zn{sub y}RE{sub z} phase with a few Ca (T Prime phase) is formed. Black-Right-Pointing-Pointer The formation of the T Prime phase leads to the loss of the Mg-Zn and Ca{sub 2}Mg{sub 6}Zn{sub 3} phases. Black-Right-Pointing-Pointer The composition of the T Prime phase differs from the grain interior to the grain boundary.

Leaching studies of radionuclides from solidified wastes with thermosetting resin

International Nuclear Information System (INIS)

Suzuki, K.; Kuribayashi, H.; Morimitsu, W.; Ono, I.

1982-01-01

This paper reports on studies of the leachability of Co-60 and Cs-137 from simulated LWR radwastes solidified with thermosetting resin and evaluates the effects of chemical fixation on leachability. It is concluded that insolubilization by a nickel-ferrocyanide compound offers an effective chemical fixation of these radionuclides and is a recommended pretreating method for radwastes that are to be solidified. 2 figures

Characterization of the Ni-45wt% Ti shape memory alloy rapidly solidified; Caracterizacao da liga Ni-45wt%Ti com efeito de memoria de forma solidificadas rapidamente

Energy Technology Data Exchange (ETDEWEB)

Anselmo, G.C.S.; Castro, W.B. de; Araujo, C.J. de, E-mail: walman@dem.ufcg.edu.b [Universidade Federal de Campina Grande (UAEM/UFCG), PB (Brazil). Unidade Academica de Engenharia Mecanica

2010-07-01

One important challenge of microsystems design is the implementation of miniaturized actuation principles efficient at the micro-scale. Shape memory alloys (SMAs) have early on been considered as a potential solution to this problem as these materials offer attractive properties like a high-power to weight ratio, large deformation and the capability to be processed at the micro-scale. shape memory characteristics of Ni-45wt%Ti alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray. In these experiments particular attention has been paid to change the velocity of cooling wheel from 30 to 50 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate on martensitic transformation behaviors and structure are discussed. (author)

Rapid Synthesis and Formation Mechanism of Core-Shell-Structured La-Doped SrTiO3 with a Nb-Doped Shell

Directory of Open Access Journals (Sweden)

Nam-Hee Park

2015-07-01

Full Text Available To provide a convenient and practical synthesis process for metal ion doping on the surface of nanoparticles in an assembled nanostructure, core-shell-structured La-doped SrTiO3 nanocubes with a Nb-doped surface layer were synthesized via a rapid synthesis combining a rapid sol-precipitation and hydrothermal process. The La-doped SrTiO3 nanocubes were formed at room temperature by a rapid dissolution of NaOH pellets during the rapid sol-precipitation process, and the Nb-doped surface (shell along with Nb-rich edges formed on the core nanocubes via the hydrothermal process. The formation mechanism of the core-shell-structured nanocubes and their shape evolution as a function of the Nb doping level were investigated. The synthesized core-shell-structured nanocubes could be arranged face-to-face on a SiO2/Si substrate by a slow evaporation process, and this nanostructured 10 μm thick thin film showed a smooth surface.

Phase transformations in the reaction cell of TiNi-based sintered systems

Science.gov (United States)

Artyukhova, Nadezhda; Anikeev, Sergey; Yasenchuk, Yuriy; Chekalkin, Timofey; Gunther, Victor; Kaftaranova, Maria; Kang, Ji-Hoon; Kim, Ji-Soon

2018-05-01

The present work addresses the structural-phase state changes of porous TiNi-based compounds fabricated by reaction sintering (RS) of Ti and Ni powders with Co, Mo, and no additives introduced. The study also emphasizes the features of a reaction cell (RC) during the transition from the solid- to liquid-phase sintering. Mechanisms of phase transformations occurring in the solid phase, involving the low-melting Ti2Ni phase within the RC, have been highlighted. Also, the intermediate Ti2Ni phase had a crucial role to provide both the required RS behavior and modified phase composition of RS samples, and besides, it is found to be responsible for the near-equiatomic TiNi saturation of the melt. Both cobalt and molybdenum additives are shown to cause additional structuring of the transition zone (TZ) at the Ti2Ni‑TiNi interface and broadening of this zone. The impact of Co and Mo on the Ti2Ni phase is evident through fissuring of this phase layer, which is referred to solidified stresses increased in the layer due to post-alloying defects in the structure.

Leaching behavior of solidified plastics radioactive wastes

International Nuclear Information System (INIS)

Yook, Chong Chul; Lee, Byung Hun; Jae, Won Mok; Kim, Kyung Eung

1986-01-01

It is highly needed to develope the solidification process to dispose safely the radioactive wastes increasing with the growth of the nuclear industry. The leaching mechanisms of the solidified plastic wastes were investigated and the leaching rates of the plastic wastes were also measured among the many solidification processes. In addition, the transport equation based on the diffusion or the diffusion-dissolution was compared with the empirical equation derived from the experimental data by graphical method. Consequently, leaching process of the solidified plastic wastes is quite well agreed with the mass transport theory, but it may be difficult to simulate leaching process by diffusion dissolution mechanism. But the theoretical equation could be applicable to the cumulative amount of radionuclides leached form the plastic wastes disposed into the environment. (Author)

On confirmation of abandonment of imported waste (glass solidified bodies) outside business places

International Nuclear Information System (INIS)

1996-01-01

Electric power companies entrust the reprocessing of spent fuel generated from nuclear power stations to COGEMA in France, and in April, 1995, 28 high level radioactive wastes (glass solidified bodies) generated by the reprocessing were returned. When these glass solidified wastes are abandoned in the waste management facility of Japan Nuclear Fuel Service Co., it was decided to receive the confirmation of the prime minister on the measures based on the relevant law. Four electric power companies submitted the application and the explanation paper. As to the contents of the glass solidified wastes, the technical inspection was carried out by Bureau Veritas. Considering that this import of glass solidified wastes is the first in Japan, Science and Technology Agency carried out the measurement of all 28 wastes. The results are reported. It was confirmed that the measures for the abandonment taken by four electric power companies conform to the stipulation. The contents of the confirmation are reported in the order of the stipulation. These wastes were solidified with borosilicate glass in 5 mm thick stainless steel vessels, and the welding was done properly. (K.I.)

Fabrication and Mechanical Properties of TiC/TiAl Composites

Institute of Scientific and Technical Information of China (English)

YUE Yun-long; GONG Yan-sheng; WU Hai-tao; WANG Chuan-bin; ZHANG Lian-meng

2004-01-01

TiC/TiAl composites with different TiC content were fabricated by rapid heating technique ofspark plasma sintering (SPS). The effect of TiC particles on microstructure and mechanical properties of TiAl matrix was investigated. The results indicate that grain sizes of TiAl matrix decrease and mechanical properties are improved because of the addition of TiC particles. The composites display a 26.8% increase in bending strength when10wt% TiC is added and 43.8% improvement in fracture toughness when 5 wt % TiC is added compared to valuesof TiC-free materials. Grain-refinement and dispersion-strengthening were the main strengthening mechanism. Theimprovement of fracture toughness was due to the deflexion of TiC particles to the crack.

Production and properties of solidified high-level waste

International Nuclear Information System (INIS)

Brodersen, K.

1980-08-01

Available information on production and properties of solidified high-level waste are presented. The review includes literature up to the end of 1979. The feasibility of production of various types of solidified high-level wast is investigated. The main emphasis is on borosilicate glass but other options are also mentioned. The expected long-term behaviour of the materials are discussed on the basis of available results from laboratory experiments. Examples of the use of the information in safety analysis of disposal in salt formations are given. The work has been made on behalf of the Danish utilities investigation of the possibilities of disposal of high-level waste in salt domes in Jutland. (author)

Ultrasensitive determination of mercury in human saliva by atomic fluorescence spectrometry based on solidified floating organic drop microextraction

International Nuclear Information System (INIS)

Yuan, C.-G.; Wang, J.; Jin, Y.

2012-01-01

We report on a new, rapid and simple method for the determination of ultra-trace quantities of mercury ion in human saliva. It is based on solidified floating organic drop microextraction and detection by cold vapor atomic fluorescence spectrometry (CV-AFS). Mercury ion was complexed with diethyldithiocarbamate, and the hydrophobic complex was then extracted into fine droplets of 1-undecanol. By cooling in an ice bath after extraction, the droplets in solution solidify to form a single ball floating on the surface of solution. The solidified micro drop containing the mercury complex was then transferred for determination by CV-AFS. The effects of pH value, concentration of chelating reagent, quantity of 1-undecanol, sample volume, equilibration temperature and time were investigated. Under the optimum conditions, the preconcentration of a 25-mL sample is accomplished with an enrichment factor of 182. The limit of detection is 2.5 ng L -1 . The relative standard deviation for seven replicate determinations at 0.1 ng mL -1 level is 4.1%. The method was applied to the determination of mercury in saliva samples collected from four volunteers. Two volunteers having dental amalgam fillings had 0.4 ng mL -1 mercury in their saliva, whereas mercury was not detectable in the saliva of two volunteers who had no dental fillings. (author)

Welding and Weldability of Directionally Solidified Single Crystal Nickel-Base Superalloys

Energy Technology Data Exchange (ETDEWEB)

Vitek, J M; David, S A; Reed, R W; Burke, M A; Fitzgerald, T J

1997-09-01

Nickel-base superalloys are used extensively in high-temperature service applications, and in particular, in components of turbine engines. To improve high-temperature creep properties, these alloys are often used in the directionally-solidified or single-crystal form. The objective of this CRADA project was to investigate the weldability of both experimental and commercial nickel-base superalloys in polycrystalline, directionally-solidified, and single-crystal forms.

The evaluation of solidifying performance of heavy metal waste using cementitious materials (2)

International Nuclear Information System (INIS)

Fujita, Hideki; Harasawa, Shuichi

2005-02-01

Some of radioactive waste generated from JNC's facilities contain the poisonous substances such as lead, cadmium and mercury. In order to establish an appropriate method of the treatment of these heavy metals, solidification performance was evaluated using cementitious materials. In this report, the solidification performance of lead and mercury, which accounts for relatively high ratio in total wastes, was evaluated. The results are summarized below: 1. The test of stabilization process of mercury. The conversion process from mercury to the powdery mercury sulfide (red) was examined on the beaker scale. As a result, it was confirmed that the conversion was possible using the liquid phase reaction at 80deg C by the addition of sulfur powder with the NaOH solution. After the process, the mercury concentration in the filtrate was relatively high (0.6 mass%), so it was judged that the reuse of the recovered mercury waste fluid was indispensable. 2. The fabrication and evaluation of solidified wastes. The solidified waste were fabricated with cementitious material, and were evaluated by the measurement of one-axis compressive strength, the elution ratio of lead, mercury and so on. Powdery lead sulfide and the mercury sulfide of reagent were used as model waste. (1) solidification test of the lead waste. It was confirmed one-axis compressive strength for all solidified waste to pass the technical standards 15 kg/cm 2 (1.5 Mpa) for homogeneously solidified waste as the Low-level Radioactive Waste Disposal Center in Aomori Prefecture, and as for the elution ratio of lead, it had obtained the better result (0.06 mg/L) at the case of solidification of sulfide lead 30 mass% packed in the total solidified waste by using Highly Fly-ash contained Silica fume Cement (HFSC) than standard value (0.3 mg/L) at Regulations of Waste Management and Public Cleansing Law. Additionally, it was confirmed the using admixture of the inorganic reducing agent such as the Iron (II) chloride

Validatin of miniaturised tensile testing on DMLS TI6AL4V (ELI specimens

Directory of Open Access Journals (Sweden)

Van Zyl, Ian

2016-11-01

Full Text Available Direct metal laser sintering (DMLS is a relatively new technology that is developing rapidly. Since DMLS material is created by melting/solidifying tracks and layers from powder, even building geometry can influence the mechanical properties. To certify a material, the testing specimens must be designed and manufactured according to the appropriate standards. Miniaturised tensile DMLS samples could be a good alternative for express quality control, and could reduce the cost of DMLS-specific testing. In this study, as-built and stress-relieved miniaturised tensile DMLS Ti6Al4V (ELI specimens with different surface qualities were investigated. The fracture surfaces and mechanical properties of the mini-tensile specimens were analysed and compared with standard full-sized specimens also manufactured by DMLS. The obtained data showed the applicability of mini-tensile tests for the express analysis of DMLS objects if a correction factor is applied for the calculation of the load-bearing cross-section of the specimen.

Rapid fabrication of mesoporous TiO2 thin films by pulsed fibre laser for dye sensitized solar cells

Science.gov (United States)

Hadi, Aseel; Alhabradi, Mansour; Chen, Qian; Liu, Hong; Guo, Wei; Curioni, Michele; Cernik, Robert; Liu, Zhu

2018-01-01

In this paper we demonstrate for the first time that a fibre laser with a wavelength of 1070 nm and a pulse width of milliseconds can be applied to generate mesoporous nanocrystalline (nc) TiO2 thin films on ITO coated glass in ambient atmosphere, by complete vaporisation of organic binder and inter-connection of TiO2 nanoparticles, without thermally damaging the ITO layer and the glass substrate. The fabrication of the mesoporous TiO2 thin films was achieved by stationary laser beam irradiation of 1 min. The dye sensitized solar cell (DSSC) with the laser-sintered TiO2 photoanode reached higher power conversion efficiency (PCE) of 3.20% for the TiO2 film thickness of 6 μm compared with 2.99% for the furnace-sintered. Electrochemical impedance spectroscopy studies revealed that the laser sintering under the optimised condition effectively decreased charge transfer resistance and increased electron lifetime of the TiO2 thin films. The use of the fibre laser with over 40% wall-plug efficiency offers an economically-feasible, industrial viable solution to the major challenge of rapid fabrication of large scale, mass production of mesoporous metal oxide thin film based solar energy systems, potentially for perovskite and monolithic tandem solar cells, in the future.

Reactive Ni/Ti nanolaminates

International Nuclear Information System (INIS)

Adams, D. P.; Bai, M. M.; Rodriguez, M. A.; McDonald, J. P.; Jones, E. Jr.; Brewer, L.; Moore, J. J.

2009-01-01

Nickel/titanium nanolaminates fabricated by sputter deposition exhibited rapid, high-temperature synthesis. When heated locally, self-sustained reactions were produced in freestanding Ni/Ti multilayer foils characterized by average propagation speeds between ∼0.1 and 1.4 m/s. The speed of a propagating reaction front was affected by total foil thickness and bilayer thickness (layer periodicity). In contrast to previous work with compacted Ni-Ti powders, no preheating of Ni/Ti foils was required to maintain self-propagating reactions. High-temperature synthesis was also stimulated by rapid global heating demonstrating low ignition temperatures (T ig )∼300-400 deg. C for nanolaminates. Ignition temperature was influenced by bilayer thickness with more coarse laminate designs exhibiting increased T ig . Foils reacted in a vacuum apparatus developed either as single-phase B2 cubic NiTi (austenite) or as a mixed-phase structure that was composed of monoclinic B19 ' NiTi (martensite), hexagonal NiTi 2 , and B2 NiTi. Single-phase, cubic B2 NiTi generally formed when the initial bilayer thickness was made small.

Detection of free liquid in containers of solidified radioactive waste

Science.gov (United States)

Greenhalgh, Wilbur O.

1985-01-01

A method of nondestructively detecting the presence of free liquid within a sealed enclosure containing solidified waste by measuring the levels of waste at two diametrically opposite locations while slowly tilting the enclosure toward one of said locations. When the measured level remains constant at the other location, the measured level at said one location is noted and any measured difference of levels indicates the presence of liquid on the surface of the solidified waste. The absence of liquid in the enclosure is verified when the measured levels at both locations are equal.

Microstructure and mechanical properties of an Al–Mg alloy solidified under high pressures

International Nuclear Information System (INIS)

Jie, J.C.; Zou, C.M.; Brosh, E.; Wang, H.W.; Wei, Z.J.; Li, T.J.

2013-01-01

Highlights: •Al–42.2Mg alloy was solidified under pressures of 1, 2, and 3 GPa and the microstructure analyzed. •A thermodynamic calculation of the Al–Mg phase diagram at high pressures was performed. •The phase content changes from predominantly γ-Al 12 Mg 17 at 1 GPa to FCC solid solution at 3 GPa. •The β-Al 3 Mg 2 is predicted to remain stable at low temperatures but is not observed. •The alloy solidified at high pressure has remarkably enhanced ultimate tensile strength. -- Abstract: Phase formation, the microstructure and its evolution, and the mechanical properties of an Al–42.2 at.% Mg alloy solidified under high pressures were investigated. After solidification at pressures of 1 GPa and 2 GPa, the main phase is the γ phase, richer in Al than in equilibrium condition. When the pressure is further increased to 3 GPa, the main phase is the supersaturated Al(Mg) solid solution with Mg solubility up to 41.6 at.%. Unlike in similar alloys solidified at ambient pressure, the β phase does not appear. Calculated high-pressure phase diagrams of the Al–Mg system show that although the stability range of the β phase is diminished with pressure, it is still thermodynamically stable at room temperature. Hence, the disappearance of the β phase is interpreted as kinetic suppression, due to the slow diffusion rate at high pressures, which inhibits solid–solid reactions. The Al–42.2 at.% Mg alloy solidified under 3 GPa has remarkably enhanced ultimate tensile strength compared to the alloy solidified under normal atmospheric pressure

Air-assisted liquid–liquid microextraction by solidifying the floating organic droplets for the rapid determination of seven fungicide residues in juice samples

Energy Technology Data Exchange (ETDEWEB)

You, Xiangwei [Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101 (China); College of Science, China Agricultural University, Beijing 100193 (China); Xing, Zhuokan [College of Science, China Agricultural University, Beijing 100193 (China); Liu, Fengmao, E-mail: liufengmao@cau.edu.cn [College of Science, China Agricultural University, Beijing 100193 (China); Zhang, Xu [College of Science, China Agricultural University, Beijing 100193 (China)

2015-05-22

Highlights: • A novel AALLME-SFO method was firstly reported for pesticide residue analysis. • Solvent with low density and proper melting point was used as extraction solvent. • The formation of “cloudy solvent” with a syringe only. • The new method avoided the use of organic dispersive solvent. - Abstract: A novel air assisted liquid–liquid microextraction using the solidification of a floating organic droplet method (AALLME-SFO) was developed for the rapid and simple determination of seven fungicide residues in juice samples, using the gas chromatography with electron capture detector (GC-ECD). This method combines the advantages of AALLME and dispersive liquid–liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) for the first time. In this method, a low-density solvent with a melting point near room temperature was used as the extraction solvent, and the emulsion was rapidly formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent for ten times repeatedly using a 10-mL glass syringe. After centrifugation, the extractant droplet could be easily collected from the top of the aqueous samples by solidifying it at a temperature lower than the melting point. Under the optimized conditions, good linearities with the correlation coefficients (γ) higher than 0.9959 were obtained and the limits of detection (LOD) varied between 0.02 and 0.25 μg L{sup −1}. The proposed method was applied to determine the target fungicides in juice samples and acceptable recoveries ranged from 72.6% to 114.0% with the relative standard deviations (RSDs) of 2.3–13.0% were achieved. Compared with the conventional DLLME method, the newly proposed method will neither require a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly.

Air-assisted liquid–liquid microextraction by solidifying the floating organic droplets for the rapid determination of seven fungicide residues in juice samples

International Nuclear Information System (INIS)

You, Xiangwei; Xing, Zhuokan; Liu, Fengmao; Zhang, Xu

2015-01-01

Highlights: • A novel AALLME-SFO method was firstly reported for pesticide residue analysis. • Solvent with low density and proper melting point was used as extraction solvent. • The formation of “cloudy solvent” with a syringe only. • The new method avoided the use of organic dispersive solvent. - Abstract: A novel air assisted liquid–liquid microextraction using the solidification of a floating organic droplet method (AALLME-SFO) was developed for the rapid and simple determination of seven fungicide residues in juice samples, using the gas chromatography with electron capture detector (GC-ECD). This method combines the advantages of AALLME and dispersive liquid–liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) for the first time. In this method, a low-density solvent with a melting point near room temperature was used as the extraction solvent, and the emulsion was rapidly formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent for ten times repeatedly using a 10-mL glass syringe. After centrifugation, the extractant droplet could be easily collected from the top of the aqueous samples by solidifying it at a temperature lower than the melting point. Under the optimized conditions, good linearities with the correlation coefficients (γ) higher than 0.9959 were obtained and the limits of detection (LOD) varied between 0.02 and 0.25 μg L −1 . The proposed method was applied to determine the target fungicides in juice samples and acceptable recoveries ranged from 72.6% to 114.0% with the relative standard deviations (RSDs) of 2.3–13.0% were achieved. Compared with the conventional DLLME method, the newly proposed method will neither require a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly

Experiment of solidifying photo sensitive polymer by using UV LED

Science.gov (United States)

Kang, Byoung Hun; Shin, Sung Yeol

2008-11-01

The development of Nano/Micro manufacturing technologies is growing rapidly and in the same manner, the investments in these areas are increasing. The applications of Nano/Micro technologies are spreading out to semiconductor production technology, biotechnology, environmental engineering, chemical engineering and aerospace. Especially, SLA is one of the most popular applications which is to manufacture 3D shaped microstructure by using UV laser and photo sensitive polymer. To make a high accuracy and precision shape of microstructures that are required from the diverse industrial fields, the information of interaction relationship between the photo resin and the light source is necessary for further research. Experiment of solidifying photo sensitive polymer by using UV LED is the topic of this paper and the purpose of this study is to find out what relationships do the reaction of the resin have in various wavelength, power of the light and time.

Powder metallurgy Al–6Cr–2Fe–1Ti alloy prepared by melt atomisation and hot ultra-high pressure compaction

International Nuclear Information System (INIS)

Dám, Karel; Vojtěch, Dalibor; Průša, Filip

2013-01-01

Al--6Cr--2Fe--1Ti alloy was prepared by melt atomisation into rapidly solidified powder. The powder was compacted using uniaxial hot compression at an ultra-high pressure (6 GPa). The samples were pressed at 300, 400 and 500 °C. The structure, mechanical properties and thermal stability were examined and compared with those of the commercially available Al--12Si--1Cu--1Mg--1Ni casting alloy, which is considered thermally stable. It was shown that the hot compression at ultra-high pressure results in a compact and pore-free material with excellent mechanical properties. The elevated pressing temperatures were found to be effective at increasing the mechanical stability after applying the ultra-high pressure. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 °C. In addition, the Al--6Cr--2Fe--1Ti alloy exhibited very good creep resistance. A comparison between the commercial Al--12Si--1Cu--1Mg--1Ni alloy and the powder metallurgy alloy shows that this alloy has significantly better mechanical properties and thermal stability.

Powder metallurgy Al-6Cr-2Fe-1Ti alloy prepared by melt atomisation and hot ultra-high pressure compaction

Energy Technology Data Exchange (ETDEWEB)

Dam, Karel, E-mail: Karel.Dam@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Vojtech, Dalibor; Prusa, Filip [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

2013-01-10

Al--6Cr--2Fe--1Ti alloy was prepared by melt atomisation into rapidly solidified powder. The powder was compacted using uniaxial hot compression at an ultra-high pressure (6 GPa). The samples were pressed at 300, 400 and 500 Degree-Sign C. The structure, mechanical properties and thermal stability were examined and compared with those of the commercially available Al--12Si--1Cu--1Mg--1Ni casting alloy, which is considered thermally stable. It was shown that the hot compression at ultra-high pressure results in a compact and pore-free material with excellent mechanical properties. The elevated pressing temperatures were found to be effective at increasing the mechanical stability after applying the ultra-high pressure. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 Degree-Sign C. In addition, the Al--6Cr--2Fe--1Ti alloy exhibited very good creep resistance. A comparison between the commercial Al--12Si--1Cu--1Mg--1Ni alloy and the powder metallurgy alloy shows that this alloy has significantly better mechanical properties and thermal stability.

Vessel for solidifying water-impermeable radioactive waste

International Nuclear Information System (INIS)

Kiuchi, Yoshimasa; Tamada, Shin; Suzuki, Yasushi.

1993-01-01

A blend prepared by admixing silica sand, alumina powder or glass fiber, as aggregates, to epoxy resin elastic adhesives is coated on an inner surface of a steel drum can or an inner surface of a concrete vessel at a thickness of greater than 1mm followed by hardening. The addition amount of the silica sand, alumina powder or glass fiber is determined as 20 to 40% by weight, 30 to 60% by weight or 5 to 15% by weight respectively. A lid having a hole for injecting fillers is previously bonded to a container for use in solidifying radioactive materials. The strength of the coating layer is increased and a coating performance and an adhesion force are improved by admixing the aggregates, to provide a satisfactory water-impermeability. The container for use in solidifying radioactive wastes having a coating layer with an advantage of the elastic resin adhesives, strong strength and adhesion and being excellent in the water-impermeability can be obtained relatively economically. (N.H.)

Synthesis of Y2O3 particle enhanced Ni/TiC composite on TC4 Ti alloy by laser cladding%TC4钛合金表面激光熔覆法制备Y2O3颗粒增强Ni/TiC复合涂层

Institute of Scientific and Technical Information of China (English)

张可敏; 邹建新; 李军; 于治水; 王慧萍

2012-01-01

A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding.The phase component,microstructure,composition distribution and properties of the composite layer were investigated.The composite layer has graded microstructures and compositions,due to the fast melting followed by rapid solidification and cooling during laser cladding.The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified.The size of TiC dendrites decreases with increasing depth.Y2O3 fine particles distribute in the whole clad layer.The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380,which is 4 times higher than the initial hardness.The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.%采用激光熔覆法在TC4钛合金表面原位制备Y2O3颗粒增强Ni/TiC复合涂层,研究涂层的相组成、微结构、成分分布及性能.结果表明,复合涂层内的微结构和成分在深度方向具有分层现象,这主要是由激光熔覆过程的快速熔凝和冷却过程所致.在激光熔覆过程中,TiC粉末完全熔化并在凝固过程中析出为细小枝晶,这些TiC枝晶的尺寸随着深度的增加而减小,而Y2O3颗粒则分布在整个重熔层中.Y2O3颗粒增强Ni/TiC复合涂层具有较均匀的硬度,其最高值约为HV1380,比基体高4倍以上.由于复合涂层具有高的硬度,钛合金经过激光熔覆后其耐磨性得到大幅度提高.

Formation of two-way shape memory effect in rapid-quenched TiNiCu alloys

International Nuclear Information System (INIS)

Shelyakov, A.V.; Bykovsky, Yu.A.; Matveeva, N.M.; Kovneristy, Yu.K.

1995-01-01

Recently we have developed a number of devices for an optical radiation control based on the shape memory effect. A blind of rapid-quenched TiNiCu alloy having a two-way shape memory in bending was used as a basic element. So far as the rapid quenched alloy used is amorphous in initial state, it needs thermal annealing to form shape memory. This paper describes procedure of thermo-mechanical treatment, that allows to form desired two-way shape memory immediately during thermal annealing of amorphous alloy without training. It was shown that degree of two-way shape recovery depends critically on initial strain, temperature and duration of the annealing. It was experimentally determined optimum parameters of thermo-mechanical treatment to achieve maximum two-way shape memory. (orig.)

The evaluation of solidifying performance of heavy metal waste using cementitious materials

International Nuclear Information System (INIS)

Takei, Akihiko; Fujita, Hideki; Harasawa, Shuichi

2004-02-01

Some of radioactive waste generated form JNC's facilities contain the poisonous substances such as lead, cadmium and mercury. In order to establish an appropriate method of the treatment of these heavy metals, solidification performance was evaluated using cementitious materials. In this report, the solidification performance of lead, which accounts for relatively high ratio in total wastes, was evaluated. The results are summarized below: 1. The test of stabilization process of lead: The conversion process from block lead to the powdery lead sulfide was examined on the beaker scale. As a result, it was confirmed that the conversion was possible using the liquid phase reaction by the addition of thiourea after block lead had been dissolved by the acetic acid with bubbling air. After the process, the lead concentration in the filtrate was extremely low (0.02 mg/L), so it was judged that almost all of the lead was converted and recovered as lead sulfide. 2. The fabrication and evaluation of solidified wastes: Five types of solidified waste were fabricated with different binder, and were evaluated by the measurement of one-axis compressive strength, porosity, the elution ratio of lead, and so on. Powdery lead and sulfide lead reagent were used as model waste. As a result of the test, it was confirmed one-axis compressive strength for all solidified waste to pass the technical standards 15 kg/cm 2 (1.5 MPa) for homogeneously solidified waste as the Low-level Radioactive Waste Disposal Center in Aomori Prefecture, and as for the elution ratio of lead, it had obtained the better result (0.27 mg/L) at the case of solidification of sulfide lead 20 mass% packed in the total solidified waste by using low alkaline cement (including Hauyne mineral) than standard value (0.3 mg/L) at Regulations of Waste Management and Public Cleansing Law. Moreover, it was understood that the elution of lead had high relationship with not only the character of the binder but also the physical

Characteristics of solidified high-level waste products

International Nuclear Information System (INIS)

1979-01-01

The object of the report is to contribute to the establishment of a data bank for future preparation of codes of practice and standards for the management of high-level wastes. The work currently in progress on measuring the properties of solidified high-level wastes is being studied

Influence of Mn incorporation for Ni on the magnetocaloric properties of rapidly solidified off-stoichiometric NiMnGa ribbons

Energy Technology Data Exchange (ETDEWEB)

Dey, Sushmita; Singh, Satnam; Roy, R.K.; Ghosh, M.; Mitra, A.; Panda, A.K., E-mail: akpanda@nmlindia.org

2016-01-01

The present investigation addresses the magnetocaloric behaviour in a series of Ni{sub 77−x}Mn{sub x}Ga{sub 23} (x=23, 24, 25, 27 and 29) rapidly solidified alloys prepared in the form of ribbons by melt spinning technique. The approach of the study is to identify the off-stoichiometric composition wherein room temperature magneto-structural transformation is achieved. The alloy chemistry was tailored through Mn incorporation for Ni such that the magnetic and structural transitions were at close proximity to achieve highest entropy value of ΔS equal to 8.51 J Kg{sup −1} K{sup −1} for #Mn{sub 24} ribbon measured at an applied field of 3 T. When such transitions are more staggered as in #Mn{sub 29} the entropy value of ribbon reduced to as low as 1.61 J Kg{sup −1} K{sup −1}. Near room temperature transformations in #Mn{sub 24} ribbon have been observed through calorimetric and thermomagnetic evaluation. Reverse martensitic transformation (martensite→autstenite) temperature indicates not only distinct change in the saturation flux density but also an inter-martensitic phase. Microstructural analysis of #Mn{sub 24} alloy ribbon revealed structural ordering with the existence of plate morphology evidenced for martensitic phase. - Highlights: • Magnetocaloric effect in a series of melt spun NiMnGa ribbon is addressed. • The alloy series revealed austenitic state as well as its presence with martensite. • The morphology of the ribbons has been shown and discussed through phase analysis. • Influence of magnetising field on entropy and relative cooling power is discussed. • Influence of intermartensitic state on magnetization plots have also been shown.

Rapid thermal melted TiO2 nano-particles into ZnO nano-rod and its application for dye sensitized solar cells

International Nuclear Information System (INIS)

Chao, Ching-Hsun; Chang, Chi-Lung; Chan, Chien-Hung; Lien, Shui-Yang; Weng, Ko-Wei; Yao, Kuo-Shan

2010-01-01

TiO 2 nano-particles with an anchored ZnO nano-rod structure were synthesized using the hydrothermal method to grow ZnO nano-rods and coated TiO 2 nano-particles on ZnO nano-rods using the rapid thermal annealing method on ITO conducting glass pre-coated with nano porous TiO 2 film. The XRD study showed that there was little difference in crystal composition for various types of TiO 2 nano-particles anchored to ZnO nano-rods. The as-prepared architecture was characterized using field-emission scanning electron microscopy (FE-SEM). Films with TiO 2 nano-particles anchored to ZnO nano-rods were used as electrode materials to fabricate dye sensitized solar cells (DSSCs). The best solar energy conversion efficiency of 2.397% was obtained by modified electrode material, under AM 1.5 illumination, achieved up to J sc = 15.382 mA/cm 2 , V oc = 0.479 V and fill factor = 32.8%.

Magnetic Fe3O4@TiO2 Nanoparticles-based Test Strip Immunosensing Device for Rapid Detection of Phosphorylated Butyrylcholinesterase

Energy Technology Data Exchange (ETDEWEB)

Ge, Xiaoxiao; Zhang, Weiying; Lin, Yuehe; Du, Dan

2013-12-15

An integrated magnetic nanoparticles-based test-strip immunosensing device was developed for rapid and sensitive quantification of phosphorylated butyrylcholinesterase (BChE), the biomarker of exposure to organophosphous pesticides (OP), in human plasma. In order to overcome the difficulty in scarce availability of OP-specific antibody, here magnetic Fe3O4@TiO2 nanoparticles were used and adsorbed on the test strip through a small magnet inserted in the device to capture target OP-BChE through selective binding between TiO2 and OP moiety. Further recognition was completed by horseradish peroxidase (HRP) and anti-BChE antibody (Ab) co-immobilized gold nanoparticles (GNPs). Their strong affinities among Fe3O4@TiO2, OP-BChE and HRP/Ab-GNPs were characterized by quartz crystal microbalance (QCM), surface plasmon resonance (SPR) and square wave voltammetry (SWV) measurements. After cutting off from test strip, the resulted immunocomplex (HRP/Ab-GNPs/OP-BChE/Fe3O4@TiO2) was measured by SWV using a screen printed electrode under the test zone. Greatly enhanced sensitivity was achieved by introduction of GNPs to link enzyme and antibody at high ratio, which amplifies electrocatalytic signal significantly. Moreover, the use of test strip for fast immunoreactions reduces analytical time remarkably. Coupling with a portable electrochemical detector, the integrated device with advanced nanotechnology displays great promise for sensitive, rapid and in-filed on-site evaluation of OP poisoning.

Microstructure and orientation evolution in unidirectional solidified Al–Zn alloys

Energy Technology Data Exchange (ETDEWEB)

Chen, Zhongwei, E-mail: chzw@nwpu.edu.cn; Wang, Enyuan; Hao, Xiaolei

2016-06-14

Morphological instability and growth orientation evolution during unidirectional solidification of Al–Zn alloys with different pulling speeds were investigated by X-ray diffraction (XRD) and electron back-scatter diffraction (EBSD) in scanning electron microscope (SEM). The experimental results show that, as the pulling speed increases, the primary dendrite spacing becomes smaller gradually and dendrite trunks incline to the heat flow direction perfectly in unidirectional solidified Al–9.8 wt%Zn and Al–89 wt%Zn alloys. However, regardless of the pulling speed in unidirectional solidified Al–Zn alloys under fixed thermal gradient, the regular dendrites with <100> directions of primary trunks and secondary arms in 9.8 wt% Zn composition are replaced by <110> dendrites of primary trunks and secondary arms in 89 wt% Zn composition. In unidirectional solidified Al–32 wt% Zn alloy, cellular, fractal seaweed, and stabilized seaweed structures were observed at high pulling speeds. At a high pulling speed of 1000 µm/s, seaweed structures transform to the columnar dendrites with <110> trunks and <100> arms. The above orientation evolution can be attributed to low anisotropy of solid-liquid interface energy and the seaweed structure is responsible for isotropy of {111} planes.

Site Simulation of Solidified Peat: Lab Monitoring

Science.gov (United States)

Durahim, N. H. Ab; Rahman, J. Abd; Tajuddin, S. F. Mohd; Mohamed, R. M. S. R.; Al-Gheethi, A. A.; Kassim, A. H. Mohd

2018-04-01

In the present research, the solidified peat on site simulation is conducted to obtain soil leaching from soil column study. Few raw materials used in testing such as Ordinary Portland Cement (OPC), Fly ash (FA) and bottom ash (BA) which containing in solidified peat (SP), fertilizer (F), and rainwater (RW) are also admixed in soil column in order to assess their effects. This research was conducted in two conditions which dry and wet condition. Distilled water used to represent rainfall during flushing process while rainwater used to gain leaching during dry and wet condition. The first testing made after leaching process done was Moisture Content (MC). Secondly, Unconfined Compressive Strength (UCS) will be conducted on SP to know the ability of SP strength. These MC and UCS were made before and after SP were applied in soil column. Hence, the both results were compared to see the reliability occur on SP. All leachate samples were tested using Absorption Atomic Spectroscopy (AAS), Ion Chromatography (IC) and Inductively-Coupled Plasma Spectrophotometry (ICP-MS) testing to know the anion and cation present in it.

Enhanced Photoelectrochemical Behavior of H-TiO2 Nanorods Hydrogenated by Controlled and Local Rapid Thermal Annealing.

Science.gov (United States)

Wang, Xiaodan; Estradé, Sonia; Lin, Yuanjing; Yu, Feng; Lopez-Conesa, Lluis; Zhou, Hao; Gurram, Sanjeev Kumar; Peiró, Francesca; Fan, Zhiyong; Shen, Hao; Schaefer, Lothar; Braeuer, Guenter; Waag, Andreas

2017-12-01

Recently, colored H-doped TiO 2 (H-TiO 2 ) has demonstrated enhanced photoelectrochemical (PEC) performance due to its unique crystalline core-disordered shell nanostructures and consequent enhanced conduction behaviors between the core-shell homo-interfaces. Although various hydrogenation approaches to obtain H-TiO 2 have been developed, such as high temperature hydrogen furnace tube annealing, high pressure hydrogen annealing, hydrogen-plasma assisted reaction, aluminum reduction and electrochemical reduction etc., there is still a lack of a hydrogenation approach in a controlled manner where all processing parameters (temperature, time and hydrogen flux) were precisely controlled in order to improve the PEC performance of H-TiO 2 and understand the physical insight of enhanced PEC performance. Here, we report for the first time a controlled and local rapid thermal annealing (RTA) approach to prepare hydrogenated core-shell H-TiO 2 nanorods grown on F:SnO 2 (FTO) substrate in order to address the degradation issue of FTO in the typical TiO 2 nanorods/FTO system observed in the conventional non-RTA treated approaches. Without the FTO degradation in the RTA approach, we systematically studied the intrinsic relationship between the annealing temperature, structural, optical, and photoelectrochemical properties in order to understand the role of the disordered shell on the improved photoelectrochemical behavior of H-TiO 2 nanorods. Our investigation shows that the improvement of PEC performance could be attributed to (i) band gap narrowing from 3.0 to 2.9 eV; (ii) improved optical absorption in the visible range induced by the three-dimensional (3D) morphology and rough surface of the disordered shell; (iii) increased proper donor density; (iv) enhanced electron-hole separation and injection efficiency due to the formation of disordered shell after hydrogenation. The RTA approach developed here can be used as a suitable hydrogenation process for TiO 2 nanorods

Effect of titanium content and cooling rate on the microstructure and martensitic transformation of rapidly solidified Ti-Ni shape memory alloys; Influencia do Ti e da taxa de resfriamento na microestrutura e na temperatura M{sub S} em ligas Ni-Ti com EMF solidificadas rapidamente

Energy Technology Data Exchange (ETDEWEB)

Anselmo, George Carlos dos Santos; Castro, Walman Benicio de, E-mail: georgeanselmo@yahoo.com.br, E-mail: walman.castro@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

2017-01-15

One important challenge of microsystems design is the implementation of efficient principles of miniaturized actuation at the micro-scale. Shape memory alloys (SMAs) have early been considered as a potential solution to this problem as these materials offer attractive properties like a high-power to weight ratio, large deformation and the capability to be micro-scale processed. Alloys of composition Ni-44,8wt%Ti and Ni- 45,3wt%Ti were produced using the melt spinning method in air atmosphere. Ribbons obtained in this process showed martensitic grain size between 5 and 30 μm, depending on the alloy composition and the linear velocity of the wheel. (author)

A simple biogenic route to rapid synthesis of Au-TiO{sub 2} nanocomposites by electrochemically active biofilms

Energy Technology Data Exchange (ETDEWEB)

Kalathil, Shafeer; Khan, Mohammad Mansoob [Yeungnam University, School of Chemical Engineering (Korea, Republic of); Banerjee, Arghya Narayan [Yeungnam University, School of Mechanical Engineering (Korea, Republic of); Lee, Jintae; Cho, Moo Hwan, E-mail: mhcho@ynu.ac.kr [Yeungnam University, School of Chemical Engineering (Korea, Republic of)

2012-08-15

Deposition of gold on titanium dioxide (TiO{sub 2}) nanoparticles is highly beneficial for maximizing the efficiency of many photocatalytic reactions. In this study, we have reported for the first time the use of an electrochemically active biofilm (EAB) for the synthesis of Au-TiO{sub 2} nanocomposite with sodium acetate as the electron donor. The EAB acts as an electron generator for the reduction of gold ions on the surface of TiO{sub 2} nanoparticles. It was observed that the TiO{sub 2} plays not only as a support for the gold nanoparticles but also as a storage of electrons produced by the EAB within the particles. These stored electrons dramatically increase the reduction of gold ions and hence we have observed the formation of the Au-TiO{sub 2} nanocomposites within 90 min. A mechanism of the nanocomposite formation is also proposed. The as-synthesized nanocomposites were characterized by UV-Vis absorption spectroscopy to monitor the proper formation of the nanocomposites. X-ray diffraction and transmission electron microscopic analyses were performed to determine the structural and microstructural properties of the nanocomposites. High-resolution transmission electron micrographs depict the proper formation of the Au-TiO{sub 2} nanocomposites with gold nanoparticle size varying from 5 to 10 nm with an increase in the gold precursor concentration. Zeta potential measurements were used to investigate surface charges of the as-synthesized nanocomposites. This novel biogenic route represents a unique pathway for the low cost, eco-friendly, rapid, and controlled synthesis of nanostructured Au-TiO{sub 2} hybrid systems which will truly revolutionize the synthetic fields of nanocomposites.

Development of precipitation strengthened brass with Ti and Sn alloying elements additives by using water atomized powder via powder metallurgy route

Energy Technology Data Exchange (ETDEWEB)

Li, Shufeng, E-mail: shufengli@hotmail.com [Joining and Welding Research Institute, Osaka University, Osaka (Japan); Imai, Hisashi; Kondoh, Katsuyoshi [Joining and Welding Research Institute, Osaka University, Osaka (Japan); Kojima, Akimichi; Kosaka, Yoshiharu [San-Etsu Metals Co. LTD., 1892 OHTA, Tonami, Toyama (Japan); Yamamoto, Koji; Takahashi, Motoi [Nippon Atomized Metal Powders Corporation, 87-16, Nishi-Sangao, Noda, Chiba (Japan)

2012-08-15

Effect of Ti and Sn alloying elements on microstructure and mechanical properties of 60/40 brass has been studied via the powder metallurgy (P/M) route. The water-atomized BS40-0.6Sn1.0Ti (Cu40wt%Zn-0.6wt%Sn1.0wt%Ti) pre-alloyed powder was consolidated at various temperatures within range of 400-600 Degree-Sign C using spark plasma sintering (SPS) and hot extrusion was carried out at 500 Degree-Sign C. Effects of extrusion temperature on microstructure and tensile strength were investigated by employing SEM-EDS/EBSD, TEM, XRD and tensile test. Results indicated that super-saturated solid solution Ti and Sn elements created high chemical potential for a precipitate reaction in rapidly solidified brass powder, which showed significant strengthening effects on the extruded sample consolidated at lower temperature. Solid solubility of Ti in brass matrix decreased with increasing of sintering temperature, thus resulted in degradation of mechanical properties. Consequently, lower hot processing temperature is necessary to obtain excellent mechanical properties for BS40-0.6Sn1.0Ti during sintering and extrusion. An yield strength of 398 MPa and ultimate tensile strength of 615 MPa were achieved, they respectively showed 31.3% and 22.9% higher values than those of extruded Cu40Zn brass. -- Graphical abstract: The Ti and Sn alloying elements additions showed significant grain refinement on Cu40Zn-0.6Sn1.0Ti brass (b) as comparing with that of the conventional Cu40Zn brass (a), detected by electron backscatter diffraction (EBSD) technique. The grain boundaries maps of (a) BS40 (b) BS40-0.6Sn1.0Ti SPS compact sintered at 400 Degree-Sign C reveals by electron backscatter diffraction (EBSD) technique. Highlights: Black-Right-Pointing-Pointer Alloying elements Ti and Sn are proposed as additives in 60/40 brass. Black-Right-Pointing-Pointer Super-saturated Ti in powder creates high chemical potential for precipitation. Black-Right-Pointing-Pointer CuSn{sub 3}Ti{sub 5

Influence of quench rates on the properties of rapidly solidified ...

Indian Academy of Sciences (India)

Unknown

Abstract. FeNbCuSiB based materials were produced in the form of ribbons by rapid solidification techniques. The crystallization, magnetic, mechanical and corrosion behaviour were studied for the prepared materials as a function of quenching rate from liquid to the solid state. Higher quench rates produced a more ...

A Study on Factors Affecting Strength of Solidified Peat through XRD and FESEM Analysis

Science.gov (United States)

Rahman, J. A.; Napia, A. M. A.; Nazri, M. A. A.; Mohamed, R. M. S. R.; Al-Geethi, A. S.

2018-04-01

Peat is soft soil that often causes multiple problems to construction. Peat has low shear strength and high deformation characteristics. Thus, peat soil needs to be stabilized or treated. Study on peat stabilization has been conducted for decades with various admixtures and mixing formulations. This project intends to provide an overview of the solidification of peat soil and the factors that affecting the strength of solidified peat soil. Three types of peats which are fabric, hemic and sapric were used in this study to understand the differences on the effect. The understanding of the factors affecting strength of solidified peat in this study is limited to XRD and FESEM analysis only. Peat samples were collected at Pontian, Johor and Parit Raja, Johor. Peat soil was solidified using fly ash, bottom ash and Portland cement with two mixing formulation following literature review. The solidified peat were cured for 7 days, 14 days, 28 days and 56 days. All samples were tested using Unconfined Compressive Strength Test (UCS), X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM). The compressive strength test of solidified peat had shown consistently increase of sheer strength, qu for Mixing 1 while decrease of its compressive strength value for Mixing 2. All samples were tested and compared for each curing days. Through XRD, it is found that all solidified peat are dominated with pargasite and richterite. The highest qu is Fabric Mixing 1(FM1) with the value of 105.94 kPa. This sample were proven contain pargasite. Samples with high qu were observed to be having fly ash and bottom ash bound together with the help of pargasite. Sample with decreasing strength showed less amount of pargasite in it. In can be concluded that XRD and FESEM findings are in line with UCS values.

Method of solidifying powderous wastes

International Nuclear Information System (INIS)

Kakimoto, Akira; Miyake, Takashi; Sato, Shuichi; Inagaki, Yuzo.

1985-01-01

Purpose: To improve the properties of solidification products, in the case of solidifying powderous wastes with thermosetting resins. Method. A solvent for the solution of the thermosetting resin is admixed with the powderous wastes into a paste-like form prior to adding the resin to the wastes, which are then mixed with the resin solution. As the result, those solidification products having the specific gravity and the compression strength more excellent than those of the conventional ones, and much higher than the reference values can be obtained. (Kamimura, M.)

Effects of Microalloying on the Microstructures and Mechanical Properties of Directionally Solidified Ni-33(at.%)Al-31Cr-3Mo Eutectic Alloys Investigated

Science.gov (United States)

Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

2002-01-01

Despite nickel aluminide (NiAl) alloys' attractive combination of oxidation and thermophysical properties, their development as replacements for superalloy airfoils in gas turbine engines has been largely limited by difficulties in developing alloys with an optimum combination of elevated-temperature creep resistance and room-temperature fracture toughness. Alternatively, research has focused on developing directionally solidified NiAl-based in situ eutectic composites composed of NiAl and (Cr,Mo) phases in order to obtain a desirable combination of properties a systematic investigation was undertaken at the NASA Glenn Research Center to examine the effects of small additions of 11 alloying elements (Co, Cu, Fe, Hf, Mn, Nb, Re, Si, Ta, Ti, and Zr) in amounts varying from 0.25 to 1.0 at.% on the elevated-temperature strength and room-temperature fracture toughness of directionally solidified Ni-33Al-31Cr-3Mo eutectic alloy. The alloys were grown at 12.7 mm/hr, where the unalloyed eutectic base alloy exhibited a planar eutectic microstructure. The different microstructures that formed because of these fifth-element additions are included in the table. The additions of these elements even in small amounts resulted in the formation of cellular microstructures, and in some cases, dendrites and third phases were observed. Most of these elemental additions did not improve either the elevated-temperature strength or the room-temperature fracture toughness over that of the base alloy. However, small improvements in the compression strength were observed between 1200 and 1400 K when 0.5 at.% Hf and 0.25 at.% Ti were added to the base alloy. The results of this study suggest that the microalloying of Ni-33Al-31Cr-3Mo will not significantly improve either its elevatedtemperature strength or its room-temperature fracture toughness. Thus, any improvements in these properties must be acquired by changing the processing conditions.

Propertis of solidified radioactive wastes from commercial LWRs

International Nuclear Information System (INIS)

Neilson, R.M. Jr.; Colombo, P.

1978-01-01

A study has been performed to characterize the properties of solidified radioactive wastes generated in the liquid radwaste treatment systems at LWRs. The properties which have been studied are those which are pertinent in defining the relative potential for the release of radionuclides to the environment as well as others relating to the evaluation of various solidification agents on an economic and feasibility basis. The use of standard testing procedures in measuring these properties allows an intercomparison of respective properties between various types of solidified waste forms. The leachability, mechanical properties, thermal stability, radiation stability, and thermal properties of hydraulic cement, ureaformaldehyde, bitumen, and addition type polymer waste forms have been measured. In addition, the chemical sensitivity, volumetric efficiency and radiation shielding characteristics of these waste forms have been studied. Emphasis in this paper is placed on the results of studies concerning chemical compatibility of solidification agents with specific waste streams, volumetric efficiency, free standing water, and leachability

Effects of La2O3 on microstructure and wear properties of laser clad γ/Cr7C3/TiC composite coatings on TiAl intermatallic alloy

International Nuclear Information System (INIS)

Liu Xiubo; Yu Rongli

2007-01-01

The effects of La 2 O 3 addition on the microstructure and wear properties of laser clad γ/Cr 7 C 3 /TiC composite coatings on γ-TiAl intermetallic alloy substrates with NiCr-Cr 3 C 2 precursor mixed powders have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive spectrometer (EDS) and block-on-ring wear tests. The responding wear mechanisms are discussed in detail. The results are compared with that for composite coating without La 2 O 3 . The comparison indicates that no evident new crystallographic phases are formed except a rapidly solidified microstructure consisting of the primary hard Cr 7 C 3 and TiC carbides and the γ/Cr 7 C 3 eutectics distributed in the tough γ nickel solid solution matrix. Good finishing coatings can be achieved under a proper amount of La 2 O 3 -addition and a suitable laser processing parameters. The additions of rare-earth oxide La 2 O 3 can refine and purify the microstructure of coatings, relatively decrease the volume fraction of primary blocky Cr 7 C 3 to Cr 7 C 3 /γ eutectics, reduce the dilution of clad material from base alloy and increase the microhardness of the coatings. When the addition of La 2 O 3 is approximately 4 wt.%, the laser clad composite coating possesses the highest hardness and toughness. The composite coating with 4 wt.%La 2 O 3 addition can result the best enhancement of wear resistance of about 30%. However, too less or excessive addition amount of La 2 O 3 have no better influence on wear resistance of the composite coating

Filling of recovered mining areas using solidifying backfill

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Zeman Róbert

2001-12-01

Full Text Available The aim of this article is to explore the possibilities for filling recovered mining areas using solidifying backfill .The article describes the preparation of the backfill (backfill formulation with an eventual application using low quality sands, wastes from treatment plants and ash from power plants etc now to transport it as well as its application in practice. Advantageous and disadvantageous of this method are also mentioned.Several factors must be taken info consideration during the preparation process of the backfill mixture. Firstly, the quantities of each individual component must be constantly regulated. Secondly, the properties of each component must be respected. In addition, the needs of the pipeline transport system and the specific conditions of the recovered area to be filled must also be considered.Hydraulic transport and pneumo-hydraulic pipeline transport are used for handling the backfill. Pumps for transporting the solidifying backfill have to carry out demanding tasks.Due to the physical-mechanical properties of the backfill, only highly powerful pumps can be considered. Piston type pumps such as Abel Simplex and Duplex pumps with capacities of up to 100 m3.h-1 and operating pressures of up to 16 MPa would be suitable.This method has been applied abroad for different purposes. For example, solid backfill was used in the Hamr mine during exploitation of uranium using the room-and-pillar system mining method.In the Ostrava–Karvina Coal field, backfill was used in decontamination work, filling areas in a zone of dangerous deformations and for creating a dividing stratum during thick seam mining.Research info the use of solidifying backfill was also done in the Walsum mine in Germany. The aim of this research was:- to investigate the possibilities of filling a collapsing area in a working face using a solidifying mixture of power plant ash and water,- to verify whether towing pipelines proposed by the DMT corporation would be

Method and apparatus for solidifying radioactive waste

International Nuclear Information System (INIS)

Kadota, Hiroko; Kikuchi, Makoto; Tsuchiya, Hiroyuki; Tamada, Shin.

1989-01-01

The present invention concerns a method of solidifying radioactive wastes that generate heat with water curing solidifying material and the object there of is suppress the effect of heat generation of the wastes given on the solidification material. That is, it is a feature of the invention to inject water content contained in the water curable solidification material in the form of ice into the wastes. Thus, since the water content in the water curable solidification material is ice, the solidification products can be obtained by way of the following three steps: (1) ice is dissolved into water, (2) solid content of the solidification material is dissolved into water, and(3) curing reaction of the solidification material is started. Acccordingly, since the heat generated from the wastes contributes as heat of reaction when ice is dissolved into water till the solidification material has been completely filled, promotion for the curing reaction causing problems so far can be suppressed to enable easy filling. Then, after the completion of the filling of the solidification material, the heat of the wastes has an effect of promoting the second and the third steps described above to accelerate the curing reaction. (K.M.)

Method and device for solidifying radioactive waste

International Nuclear Information System (INIS)

Hayashi, Tadamasa.

1981-01-01

Purpose: To solidify radioactive waste without producing radioactive dusts by always heating and evaporating the water from liquid radioactive waste in a mixture of liquid plastic and exhausting the molten mixture of the waste residue and the plastic material. Constitution: Liquid plastic material in a tank cooled to prevent polymerization or changes of its properties is continuously supplied to the top of a heating and mixing evaporator by a constant supply pump. After the heat transfer surface of the evaporator is covered with the plastic material, radioactive waste in the tank is supplied to the evaporator via the constant supply pump. The waste is abruptly mixed with the plastic material by an agitating rotor, heated by a heater, and the evaporated water is fed to a condenser. An anhydrous molten mixture is continuously exhausted from the bottom of the evaporator into a mixture cooler, a polymerizing agent and catalyst are introduced thereinto from a polymerizing agent tank and a catalyst tank, inhibitor is introduced thereinto from a polymerization inhibitor tank as required, and is filled with the mixture a solidifying container while it is cooled for its polymerization and solidification. (Yoshino, Y.)

Effect of drying-wetting cycles on leaching behavior of cement solidified lead-contaminated soil.

Science.gov (United States)

Li, Jiang-Shan; Xue, Qiang; Wang, Ping; Li, Zhen-Ze; Liu, Lei

2014-12-01

Lead contaminated soil was treated by different concentration of ordinary Portland cement (OPC). Solidified cylindrical samples were dried at 40°C in oven for 48 h subsequent to 24h of immersing in different solution for one drying-wetting. 10 cycles were conducted on specimens. The changes in mass loss of specimens, as well as leaching concentration and pH of filtered leachates were studied after each cycle. Results indicated that drying-wetting cycles could accelerate the leaching and deterioration of solidified specimens. The cumulative leached lead with acetic acid (pH=2.88) in this study was 109, 83 and 71 mg respectively for solidified specimens of cement-to-dry soil (C/Sd) ratios 0.2, 0.3 and 0.4, compared to 37, 30, and 25mg for a semi-dynamic leaching test. With the increase of cycle times, the cumulative mass loss of specimens increased linearly, but pH of filtered leachates decreased. The leachability and deterioration of solidified specimens increased with acidity of solution. Increases of C/Sd clearly reduced the leachability and deterioration behavior. Copyright © 2014 Elsevier Ltd. All rights reserved.

Accelerated leach testing of radionuclides from solidified low-level waste

International Nuclear Information System (INIS)

Pietrzak, R.F.; Fuhrmann, M.; Franz, E.M.; Heiser, J. III; Colombo, P.

1989-01-01

This paper describes some of the work performed to develop an accelerated leach test designed to provide data that show long-term leaching behavior of solidified waste in a relatively short period of testing (1,2). The need for an accelerated leach test stems from the fact that the response of an effectively solidified waste form to the leaching process is so slow that a very long time is required to complete a test which shows the long-term leaching behavior of a waste form. Because of time limitations, as well as economic considerations, most studies have been limited to the early stages of the leaching process which is predominantly controlled by diffusion, although acknowledged to be due to also dissolution, corrosion or ion-exchange

Evaluating Primary Dendrite Trunk Diameters in Directionally Solidified Al-Si Alloys

Science.gov (United States)

Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

2014-01-01

The primary dendrite trunk diameters of Al-Si alloys that were directionally solidified over a range of processing conditions have been measured. These data are analyzed with a model based primarily on an assessment of secondary dendrite arm dissolution in the mushy zone. Good fit with the experimental data is seen and it is suggested that the primary dendrite trunk diameter is a useful metric that correlates well with the actual solidification processing parameters. These results are placed in context with the limited results from the aluminium - 7 wt. % silicon samples directionally solidified aboard the International Space Station as part of the MICAST project.

Improvement in mechanical properties of hypereutectic Al-Si-Cu alloys through sono-solidified

Directory of Open Access Journals (Sweden)

Yoshiki Tsunekawa

2014-07-01

Full Text Available For the wider applications, it is necessary to improve the ductility as well as the strength and wear-resistance of hypereutectic Al-Si-Cu alloys, which are typical light-weight wear-resistant materials. An increase in the amounts of primary silicon particles causes the modified wear-resistance of hypereutectic Al-Si-Cu alloys, but leads to the poor strength and ductility. It is known that dual phase steels composed of hetero-structure have succeeded in bringing contradictory mechanical properties of high strength and ductility concurrently. In order to apply the idea of hetero-structure to hypereutectic Al-Si-Cu alloys for the achievement of high strength and ductility along with wear resistance, ultrasonic irradiation of the molten metal during the solidification, which is called sono-solidification, was carried out from its molten state to just above the eutectic temperature. The sono-solidified Al-17Si-4Cu alloy is composed of hetero-structure, which are, hard primary silicon particles, soft non-equilibrium a -Al phase and the eutectic region. Rheo-casting was performed at just above the eutectic temperature with sono-solidified slurry to shape a disk specimen. After the rheo-casting with modified sonosolidified slurry held for 45 s at 570 篊, the quantitative optical microscope observation exhibits that the microstructure is composed of 18area% of hard primary silicon particles and 57area% of soft a -Al phase. In contrast, there exist only 5 area% of primary silicon particles and no a -Al phase in rheo-cast specimen with normally solidified slurry. Hence the tensile tests of T6 treated rheo-cast specimens with modified sono-solidified slurry exhibit improved strength and 5% of elongation, regardless of having more than 3 times higher amounts of primary silicon particles compared to that of rheo-cast specimen with normally solidified slurry.

Influence of Short-time Oxidation on Corrosion Properties of Directionally Solidified Superalloys with Different Orientations

Directory of Open Access Journals (Sweden)

MA Luo-ning

2016-07-01

Full Text Available In order to investigate the corrosion performance on intersecting and longitudinal surfaces of unoxidized and oxidized directionally solidified superalloys, Ni-base directionally solidified superalloy DZ125 and Co-base directionally solidified superalloy DZ40M were selected. Oxidation behavior on both alloys with different orientations was investigated at 1050℃ at different times, simulating the oxidation process of vanes or blades in service; subsequent electrochemical performance in 3.5%NaCl aqueous solution was studied on two orientations of unoxidized and oxidized alloys, simulating the corrosion process of superalloy during downtime. The results show that grain boundaries and sub-boundaries of directionally solidified superalloys are susceptible to corrosion and thus longitudinal surface with lower area fraction of grain boundaries has higher corrosion resistance. Compared to intersecting surface of alloys, the structure of grain boundaries of longitudinal surface is less conducive to diffusion and thus the oxidation rate on longitudinal surface is lower. Formation of oxide layers on alloys after short-time oxidation provides protective effect and enhances the corrosion resistance.

Evaluation of Carbonation Effects on Cement-Solidified Contaminated Soil Used in Road Subgrade

Directory of Open Access Journals (Sweden)

Yundong Zhou

2018-01-01

Full Text Available Cement solidification/stabilization is widely used towards contaminated soil since it has a low price and significant improvement for the structural capacity of soil. To increase the usage of the solidified matrix, cement-solidified contaminated soil was used as road subgrade material. In this study, carbonation effect that reflected the durability on strength characteristics of cement-solidified contaminated soil and the settlement of pavement were evaluated through experimental and numerical analysis, respectively. According to results, compressive strengths of specimens with 1% Pb(II under carbonation and standard curing range from 0.44 MPa to 1.17 MPa and 0.14 MPa to 2.67 MPa, respectively. The relatively low strengths were attributed to immobilization of heavy metal, which consumed part of SiO2, Al2O3, and CaO components in the cement or kaolin and reduced the hydration and pozzolanic reaction materials. This phenomenon further decreased the strength of solidified soils. The carbonation depth of 1% Cu(II or Zn(II contaminated soils was 18 mm, which significantly increased with the increase of curing time and contamination concentration. Furthermore, the finite element calculation results showed that surface settlements decreased with the increase of modulus of subgrade and the distance away from the center. At the center, the pavement settlement was proportional to the level of traffic load.

Enhanced properties of nanostructured TiO2-graphene composites by rapid sintering

Science.gov (United States)

Shon, In-Jin; Yoon, Jin-Kook; Hong, Kyung-Tae

2018-01-01

Despite of many attractive properties of TiO2, the drawback of TiO2 ceramic is low fracture toughness for widely industrial application. The method to improve the fracture toughness and hardness has been reported by addition of reinforcing phase to fabricate a nanostructured composite. In this regard, graphene has been evaluated as an ideal second phase in ceramics. Nearly full density of nanostructured TiO2-graphene composite was achieved within one min using pulsed current activated sintering. The effect of graphene on microstructure, fracture toughness and hardness of TiO2-graphene composite was evaluated using Vickers hardness tester and field emission scanning electron microscopy. The grain size of TiO2 in the TiO2-x vol% (x = 0, 1, 3, and 5) graphene composite was greatly reduced with increase in addition of graphene. Both hardness and fracture toughness of TiO2-graphene composites simultaneously increased in the addition of graphene.

Elution behavior of heavy metals from cement solidified products of incinerated ash waste - 59102

International Nuclear Information System (INIS)

Meguro, Yoshihiro; Kawato, Yoshimi; Nakayama, Takuya; Tomioka, Osamu; Mitsuda, Motoyuki

2012-01-01

A method, in which incinerated ash is solidified with a cement material, has been developed to dispose radioactive incinerated ash waste. In order to bury the solidified product, it is required that elution of hazardous heavy metals included in the ash from the solidified products is inhibited. In this study, the elution behavior of the heavy metals from the synthetic solidified products, which included Pb(II), Cd(II), and Cr(VI) and were prepared using ordinary portland cement (OPC), blast furnace slag cement (BFS), or a cement material that showed low alkalinity (LA-Cement), was investigated. Several chemicals and materials were added as additive agents to prevent the elution of the heavy metals. When OPC was used, Cd elution was inhibited, but Pb and Cr were not enough even using the additive agent examined. FeSO 4 and Na 2 S additive agents worked effective to inhibit elution of Cr. When BFS was used, the elution of Pb, Cd and Cr was inhibited for the all products prepared. In the case of LA-Cement, the elution of Pb and Cd was inhibited for the all products, but only the product that was added FeSO 4 showed good result of the elution of Cr. (authors)

Effects of La{sub 2}O{sub 3} on microstructure and wear properties of laser clad {gamma}/Cr{sub 7}C{sub 3}/TiC composite coatings on TiAl intermatallic alloy

Energy Technology Data Exchange (ETDEWEB)

Liu Xiubo [Laboratory for Laser Intelligent Manufacturing, Institute of Mechanics, Chinese Academy of Sciences, 15 Beisihuanxi Road, Beijing 100080 (China) and School of Materials and Chemical Engineering, Zhongyuan Institute of Technology, 41 Zhongyuan Western Road, Zhengzhou 450007, Henan Province (China)]. E-mail: liubobo0828@yahoo.com.cn; Yu Rongli [School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100083 (China)

2007-02-15

The effects of La{sub 2}O{sub 3} addition on the microstructure and wear properties of laser clad {gamma}/Cr{sub 7}C{sub 3}/TiC composite coatings on {gamma}-TiAl intermetallic alloy substrates with NiCr-Cr{sub 3}C{sub 2} precursor mixed powders have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive spectrometer (EDS) and block-on-ring wear tests. The responding wear mechanisms are discussed in detail. The results are compared with that for composite coating without La{sub 2}O{sub 3}. The comparison indicates that no evident new crystallographic phases are formed except a rapidly solidified microstructure consisting of the primary hard Cr{sub 7}C{sub 3} and TiC carbides and the {gamma}/Cr{sub 7}C{sub 3} eutectics distributed in the tough {gamma} nickel solid solution matrix. Good finishing coatings can be achieved under a proper amount of La{sub 2}O{sub 3}-addition and a suitable laser processing parameters. The additions of rare-earth oxide La{sub 2}O{sub 3} can refine and purify the microstructure of coatings, relatively decrease the volume fraction of primary blocky Cr{sub 7}C{sub 3} to Cr{sub 7}C{sub 3}/{gamma} eutectics, reduce the dilution of clad material from base alloy and increase the microhardness of the coatings. When the addition of La{sub 2}O{sub 3} is approximately 4 wt.%, the laser clad composite coating possesses the highest hardness and toughness. The composite coating with 4 wt.%La{sub 2}O{sub 3} addition can result the best enhancement of wear resistance of about 30%. However, too less or excessive addition amount of La{sub 2}O{sub 3} have no better influence on wear resistance of the composite coating.

Diffusion behavior in the films of Nb-Ti systems

International Nuclear Information System (INIS)

Yoshitake, Michiko; Yoshihara, Kazuhiro

1990-01-01

The diffusion behavior of substrate element into a deposited film was investigated. The observed systems were a Nb film/Ti substrate and a Ti film/Nb substrate. When the Nb film/Ti substrate was heated in a vacuum, Ti diffused very rapidly in the Nb film. The pre-exponential factor of the diffusion constant of Ti in the Nb film was 5.6x10 -2 m 2 s -1 , and the activation energy was 220 kJmol -1 . The observed activation energy is about 60% of that of Ti in the bulk Nb. On the other hand, when the Ti film/Nb substrate was heated in a vacuum, Nb did not diffuse so rapidly. Titanium diffused through the Nb film rapidly and was concentrated on the surface of the Nb film. The chemical state of the concentrated Ti was metallic, and neither titanium oxides nor titanium carbide was observed. Therefore, the driving force of the rapid diffusion of Ti in the Nb film is considered as the reduction of the surface energy of Nb film. The difference in the diffusion behavior between Ti through the Nb film and Nb through the Ti film is explained supposing that the segregation of Ti reduces the surface energy of the Nb film but the segregation of Nb does not reduce the surface energy of the Ti film. After heating of the Nb film/Ti substrate for a long time, a new phase was formed at the interface between the Nb film and the Ti substrate. The chemical composition of the new phase is about 50% of Ti and 50% of Nb. This phase has not been reported in the phase diagram of the bulk Ti-Nb system. The surface area of the Nb film is considered to be quite large, so the contribution of surface energy to the thermodynamic state of the Nb film cannot be neglected. Therefore, the chemical potential of the film is different from that of the bulk. Then, the new phase, which does not exist in the phase diagram of the bulk system, is formed by an interaction of the films. (author)

Nickel speciation in cement-stabilized/solidified metal treatment filtercakes

Energy Technology Data Exchange (ETDEWEB)

Roy, Amitava, E-mail: reroy@lsu.edu [J. Bennett Johnston, Sr., Center for Advanced Microstructures and Devices, Louisiana State University, Baton Rouge, LA 70806, USA (United States); Stegemann, Julia A., E-mail: j.stegemann@ucl.ac.uk [Centre for Resource Efficiency & the Environment, Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK (United Kingdom)

2017-01-05

Highlights: • XAS shows the same Ni speciation in untreated and stabilized/solidified filtercake. • Ni solubility is the same for untreated and stabilized/solidified filtercake. • Leaching is controlled by pH and physical encapsulation for all binders. - Abstract: Cement-based stabilization/solidification (S/S) is used to decrease environmental leaching of contaminants from industrial wastes. In this study, two industrial metal treatment filtercakes were characterized by X-ray diffractometry (XRD), thermogravimetric and differential thermogravimetric analysis (TG/DTG) and Fourier transform infrared (FTIR); speciation of nickel was examined by X-ray absorption (XAS) spectroscopy. Although the degree of carbonation and crystallinity of the two untreated filtercakes differed, α-nickel hydroxide was identified as the primary nickel-containing phase by XRD and nickel K edge XAS. XAS showed that the speciation of nickel in the filtercake was unaltered by treatment with any of five different S/S binder systems. Nickel leaching from the untreated filtercakes and all their stabilized/solidified products, as a function of pH in the acid neutralization capacity test, was essentially complete below pH ∼5, but was 3–4 orders of magnitude lower at pH 8–12. S/S does not respeciate nickel from metal treatment filtercakes and any reduction of nickel leaching by S/S is attributable to pH control and physical mechanisms only. pH-dependent leaching of Cr, Cu and Ni is similar for the wastes and s/s products, except that availability of Cr, Cu and Zn at decreased pH is reduced in matrices containing ground granulated blast furnace slag.

Site suitability criteria for solidified high level waste repositories

International Nuclear Information System (INIS)

Heckman, R.A.; Holdsworth, T.; Towse, D.F.

1979-01-01

Activities devoted to development of regulations, criteria, and standards for storage of solidified high-level radioactive wastes are reported. The work is summarized in sections on site suitability regulations, risk calculations, geological models, aquifer models, human usage model, climatology model, and repository characteristics. Proposed additional analytical work is also summarized

A united refinement technology for commercial pure Al by Al-10Ti and Al-Ti-C master alloys

International Nuclear Information System (INIS)

Ma Xiaoguang; Liu Xiangfa; Ding Haimin

2009-01-01

Because flake-like TiAl 3 particles in Al-Ti-C master alloys prepared in a melt reaction method dissolve slowly when they are added into Al melt at 720 deg. C, Ti atoms cannot be released rapidly to play the assistant role of grain refinement, leading to a poor refinement efficiency of Al-Ti-C master alloys. A united refinement technology by Al-10Ti and Al-Ti-C master alloys was put forward in this paper. The rational combination of fine blocky TiAl 3 particles in Al-10Ti and TiC particles in Al-Ti-C can improve the nucleation rate of α-Al. It not only improves the grain refinement efficiency of Al-Ti-C master alloys, but also reduces the consumption

Irradiation response of rapidly solidified Path A type prime candidate alloys

International Nuclear Information System (INIS)

Imeson, E.; Tong, C.; Lee, M.; Vander Sande, J.B.; Harling, O.K.

1981-01-01

The objective of this study is to present a first assessment of the microstructural response to neutron irradiation shown by Path A alloys prepared by rapid solidification processing. To more fully demonstrate the potential of the method, alloys with increased titanium and carbon content have been used in addition to the Path A prime candidate alloy

Pressure-jump induced rapid solidification of melt: a method of preparing amorphous materials

Science.gov (United States)

Liu, Xiuru; Jia, Ru; Zhang, Doudou; Yuan, Chaosheng; Shao, Chunguang; Hong, Shiming

2018-04-01

By using a self-designed pressure-jump apparatus, we investigated the melt solidification behavior in rapid compression process for several kinds of materials, such as elementary sulfur, polymer polyether-ether-ketone (PEEK) and poly-ethylene-terephthalate, alloy La68Al10Cu20Co2 and Nd60Cu20Ni10Al10. Experimental results clearly show that their melts could be solidified to be amorphous states through the rapid compression process. Bulk amorphous PEEK with 24 mm in diameter and 12 mm in height was prepared, which exceeds the size obtained by melt quenching method. The bulk amorphous sulfur thus obtained exhibited extraordinarily high thermal stability, and an abnormal exothermic transition to liquid sulfur was observed at around 396 K for the first time. Furthermore, it is suggested that the glass transition pressure and critical compression rate exist to form the amorphous phase. This approach of rapid compression is very attractive not only because it is a new technique of make bulk amorphous materials, but also because novel properties are expected in the amorphous materials solidified by the pressure-jump within milliseconds or microseconds.

Micro and Macro Segregation in Alloys Solidifying with Equiaxed Morphology

Science.gov (United States)

Stefanescu, Doru M.; Curreri, Peter A.; Leon-Torres, Jose; Sen, Subhayu

1996-01-01

To understand macro segregation formation in Al-Cu alloys, experiments were run under terrestrial gravity (1g) and under low gravity during parabolic flights (10(exp -2) g). Alloys of two different compositions (2% and 5% Cu) were solidified at two different cooling rates. Systematic microscopic and SEM observations produced microstructural and segregation maps for all samples. These maps may be used as benchmark experiments for validation of microstructure evolution and segregation models. As expected, the macro segregation maps are very complex. When segregation was measured along the central axis of the sample, the highest macro segregation for samples solidified at 1g was obtained for the lowest cooling rate. This behavior is attributed to the longer time available for natural convection and shrinkage flow to affect solute redistribution. In samples solidified under low-g, the highest macro-segregation was obtained at the highest cooling rate. In general, low-gravity solidification resulted in less segregation. To explain the experimental findings, an analytical (Flemings-Nereo) and a numerical model were used. For the numerical model, the continuum formulation was employed to describe the macroscopic transports of mass, energy, and momentum, associated with the microscopic transport phenomena, for a two-phase system. The model proposed considers that liquid flow is driven by thermal and solutal buoyancy, and by solidification shrinkage. The Flemings-Nereo model explains well macro segregation in the initial stages of low-gravity segregation. The numerical model can describe the complex macro segregation pattern and the differences between low- and high-gravity solidification.

Ordering in rapidly solidified Ni/sub 2/Mo

International Nuclear Information System (INIS)

Kulkarni, U.D.; Dey, G.K.; Banerjee, S.

1988-01-01

Ordering processes in the Ni-Mo system have been a subject of several investigations. Although the ordering behaviour of the Ni/sub 4/Mo and the Ni/sub 3/Mo has been examined in detail, no such study has been reported in the case of the Ni/sub 2/Mo alloy. The lack of experimental work on ordering transformations in Ni/sub 2/Mo is presumably due to the difficulty in obtaining a single phase fcc alloy of this composition. Enhanced solid solubility of Mo in Ni, which accompanies rapid solidification processing (RSP) makes the formation of such a phase possible. The ordering processes in Ni-Mo based alloys show several remarkable features. Firstly, the alloy (15 - 28 at % Mo) quenched from the α -phase filed exhibit a short range order (SRO) characterized by the presence of intensity maxima at /1 1/2 0/ fcc positions of the reciprocal space. This state of SRO has been attributed to the occurrence of 1 1/2 O spinodal ordering in the system. Secondly, the transformation from the state of SRO to the equilibrium/metastable coherent long range ordered (LRO) structures appears to take place in a continuous manner at relatively low temperatures of aging. Three different coherent LRO structures, namely: the equilibrium Ni/sub 4/Mo (prototype structure D1/sub a/) and the metastable Ni/sub 3/Mo (DO/sub 22/) and Ni/sub 2/Mo (Pt/sub 2/Mo) structures have reported to evolve from the SRO alloy, depending upon the aging treatment and the composition of the alloy

A united refinement technology for commercial pure Al by Al-10Ti and Al-Ti-C master alloys

Energy Technology Data Exchange (ETDEWEB)

Ma Xiaoguang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: xfliu@sdu.edu.cn; Ding Haimin [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

2009-03-05

Because flake-like TiAl{sub 3} particles in Al-Ti-C master alloys prepared in a melt reaction method dissolve slowly when they are added into Al melt at 720 deg. C, Ti atoms cannot be released rapidly to play the assistant role of grain refinement, leading to a poor refinement efficiency of Al-Ti-C master alloys. A united refinement technology by Al-10Ti and Al-Ti-C master alloys was put forward in this paper. The rational combination of fine blocky TiAl{sub 3} particles in Al-10Ti and TiC particles in Al-Ti-C can improve the nucleation rate of {alpha}-Al. It not only improves the grain refinement efficiency of Al-Ti-C master alloys, but also reduces the consumption.

Printing low-melting-point alloy ink to directly make a solidified circuit or functional device with a heating pen.

Science.gov (United States)

Wang, Lei; Liu, Jing

2014-12-08

A new method to directly print out a solidified electronic circuit through low-melting-point metal ink is proposed. A functional pen with heating capability was fabricated. Several typical thermal properties of the alloy ink Bi 35 In 48.6 Sn 16 Zn 0.4 were measured and evaluated. Owing to the specifically selected melting point of the ink, which is slightly higher than room temperature, various electronic devices, graphics or circuits can be manufactured in a short period of time and then rapidly solidified by cooling in the surrounding air. The liquid-solid phase change mechanism of the written lines was experimentally characterized using a scanning electron microscope. In order to determine the matching substrate, wettability between the metal ink Bi 35 In 48.6 Sn 16 Zn 0.4 and several materials, including mica plate and silicone rubber, was investigated. The resistance-temperature curve of a printed resistor indicated its potential as a temperature control switch. Furthermore, the measured reflection coefficient of a printed double-diamond antenna accords well with the simulated result. With unique merits such as no pollution, no requirement for encapsulation and easy recycling, the present printing approach is an important supplement to current printed electronics and has enormous practical value in the future.

Rapid degradation of Congo red by molecularly imprinted polypyrrole-coated magnetic TiO2 nanoparticles in dark at ambient conditions

International Nuclear Information System (INIS)

Wei, Shoutai; Hu, Xiaolei; Liu, Hualong; Wang, Qiang; He, Chiyang

2015-01-01

Highlights: • Molecularly imprinted polypyrrole-coated magnetic TiO 2 catalyst was prepared. • The catalyst degraded Congo red rapidly in dark at ambient conditions. • Degradation mechanism was proposed according to LC–MS analysis. • The catalyst can be easily recycled by a magnet. - Abstract: A novel molecularly imprinted polymer (MIP)-coated magnetic TiO 2 nanocomposite was prepared, using methyl orange (MO) as the dummy template and pyrrole as functional monomer, for degradation of Congo red (CR). The nanocomposite was characterized by Fourier transform infrared spectroscopy, thermo-gravimetric analysis, X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The imprinting efficiency of the imprinted nanoparticles was investigated by static binding test, and their degradation ability toward CR was also studied. Moreover, the effects of pH, temperature, dissolved oxygen and oscillation rate on degradation rate of CR were investigated. Results showed that the imprinted nanocomposite had higher adsorption ability for MO compared with the non-imprinted one. Moreover, it could degrade CR rapidly in dark at room temperature and atmospheric pressure and could be recycled easily by a magnet with a good reusability. A degradation mechanism was proposed according to LC–MS analysis of degradation products of CR. The new imprinted nanoparticles showed high catalytic activity at ambient conditions without light illumination and additional chemicals, and therefore, it can be potentially applied to the rapid, “green” and low-cost degradation of CR in industrial printing and dyeing wastewater

Rapid solidification and dynamic compaction of Ni-base superalloy powders

Science.gov (United States)

Field, R. D.; Hales, S. J.; Powers, W. O.; Fraser, H. L.

1984-01-01

A Ni-base superalloy containing 13Al-9Mo-2Ta (in at. percent) has been characterized in both the rapidly solidified condition and after dynamic compaction. Dynamically compacted specimens were examined in the as-compacted condition and observations related to current theories of interparticle bonding. In addition, the recrystallization behavior of the compacted material at relatively low temperature (about 0.5-0.75 Tm) was investigated.

Effect of Laser Power and Scan Speed on Melt Pool Characteristics of Commercially Pure Titanium (CP-Ti)

Science.gov (United States)

Kusuma, Chandrakanth; Ahmed, Sazzad H.; Mian, Ahsan; Srinivasan, Raghavan

2017-07-01

Selective laser melting (SLM) is an additive manufacturing technique that creates complex parts by selectively melting metal powder layer-by-layer using a laser. In SLM, the process parameters decide the quality of the fabricated component. In this study, single beads of commercially pure titanium (CP-Ti) were melted on a substrate of the same material using an in-house built SLM machine. Multiple combinations of laser power and scan speed were used for single bead fabrication, while the laser beam diameter and powder layer thickness were kept constant. This experimental study investigated the influence of laser power, scan speed, and laser energy density on the melt pool formation, surface morphology, geometry (width and height), and hardness of solidified beads. In addition, the observed unfavorable effect such as inconsistency in melt pool width formation is discussed. The results show that the quality, geometry, and hardness of solidified melt pool are significantly affected by laser power, scanning speed, and laser energy density.

Solidified self-nanoemulsifying formulation for oral delivery of combinatorial therapeutic regimen

DEFF Research Database (Denmark)

Jain, Amit K; Thanki, Kaushik; Jain, Sanyog

2014-01-01

PURPOSE: The present work reports rationalized development and characterization of solidified self-nanoemulsifying drug delivery system for oral delivery of combinatorial (tamoxifen and quercetin) therapeutic regimen. METHODS: Suitable oil for the preparation of liquid SNEDDS was selected based...

Rapid compression induced solidification of two amorphous phases of poly(ethylene terephthalate)

Energy Technology Data Exchange (ETDEWEB)

Hong, S M [Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu, 610031 (China); Liu, X R [Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu, 610031 (China); Su, L [Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu, 610031 (China); Huang, D H [Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu, 610031 (China); Li, L B [Foods Research Centre Unilever R and D, Vlaardingen Olivier van Noortlaan, 120, 3133 AT Vlaardingen (Netherlands)

2006-08-21

Melts of poly(ethylene terephthalate) were solidified by rapid compression to 2 GPa within 20 ms and by a series of comparative processes including natural cooling, slow compressing and rapid cooling, respectively. By combining XRD and differential scanning calorimetry data of the recovered samples, it is made clear that rapid compression induces two kinds of amorphous phases. One is relatively stable and can also be formed in the slow compression and the cooling processes. Another is metastable and transforms to crystalline phase at 371 K. This metastable amorphous phase cannot be obtained by slow compression or natural cooling, and its crystallization temperature is remarkably different from that of the metastable amorphous phase formed in the rapid cooling sample.

Removal of radioactive cesium from surface soils solidified using polyion complex. Rapid communication for decontamination test at Iitate-mura in Fukushima Prefecture

International Nuclear Information System (INIS)

Naganawa, Hirochika; Yanase, Nobuyuki; Mitamura, Hisayoshi; Nagano, Tetsushi; Yoshida, Zenko; Kumazawa, Noriyuki; Saitoh, Hiroshi; Kashima, Kaoru; Fukuda, Tatsuya; Tanaka, Shun-ichi

2011-01-01

We tried the decontamination of surface soils for three types of agricultural land at Nagadoro district of Iitate-mura (village) in Fukushima Prefecture, which is highly contaminated by deposits of radionuclides from the plume released from the Fukushima Daiichi nuclear power plant. The decontamination method consisted of the peeling of surface soils solidified using a polyion complex, which was formed from a salt solution of polycations and polyanions. Two types of polyion complex solution were applied to an upland field in a plastic greenhouse, a pasture, and a paddy field. The decontamination efficiency of the surface soils reached 90%, and dust release was effectively suppressed during the removal of surface soils. (author)

Functions and requirements document for interim store solidified high-level and transuranic waste

Energy Technology Data Exchange (ETDEWEB)

Smith-Fewell, M.A., Westinghouse Hanford

1996-05-17

The functions, requirements, interfaces, and architectures contained within the Functions and Requirements (F{ampersand}R) Document are based on the information currently contained within the TWRS Functions and Requirements database. The database also documents the set of technically defensible functions and requirements associated with the solidified waste interim storage mission.The F{ampersand}R Document provides a snapshot in time of the technical baseline for the project. The F{ampersand}R document is the product of functional analysis, requirements allocation and architectural structure definition. The technical baseline described in this document is traceable to the TWRS function 4.2.4.1, Interim Store Solidified Waste, and its related requirements, architecture, and interfaces.

Modeling Macrosegregation in Directionally Solidified Aluminum Alloys under Gravitational and Microgravitational Conditions.

Energy Technology Data Exchange (ETDEWEB)

Lauer, Mark A.; Poirier, David R.; Erdmann, Robert G.; Tewari, Surendra N.; Madison, Jonathan D

2014-09-01

This report covers the modeling of seven directionally solidified samples, five under normal gravitational conditions and two in microgravity. A model is presented to predict macrosegregation during the melting phases of samples solidified under microgravitational conditions. The results of this model are compared against two samples processed in microgravity and good agreement is found. A second model is presented that captures thermosolutal convection during directional solidification. Results for this model are compared across several experiments and quantitative comparisons are made between the model and the experimentally obtained radial macrosegregation profiles with good agreement being found. Changes in cross section were present in some samples and micrographs of these are qualitatively compared with the results of the simulations. It is found that macrosegregation patterns can be affected by changing the mold material.

Rapid degradation of Congo red by molecularly imprinted polypyrrole-coated magnetic TiO{sub 2} nanoparticles in dark at ambient conditions

Energy Technology Data Exchange (ETDEWEB)

Wei, Shoutai; Hu, Xiaolei; Liu, Hualong; Wang, Qiang; He, Chiyang, E-mail: chiyanghe@hotmail.com

2015-08-30

Highlights: • Molecularly imprinted polypyrrole-coated magnetic TiO{sub 2} catalyst was prepared. • The catalyst degraded Congo red rapidly in dark at ambient conditions. • Degradation mechanism was proposed according to LC–MS analysis. • The catalyst can be easily recycled by a magnet. - Abstract: A novel molecularly imprinted polymer (MIP)-coated magnetic TiO{sub 2} nanocomposite was prepared, using methyl orange (MO) as the dummy template and pyrrole as functional monomer, for degradation of Congo red (CR). The nanocomposite was characterized by Fourier transform infrared spectroscopy, thermo-gravimetric analysis, X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The imprinting efficiency of the imprinted nanoparticles was investigated by static binding test, and their degradation ability toward CR was also studied. Moreover, the effects of pH, temperature, dissolved oxygen and oscillation rate on degradation rate of CR were investigated. Results showed that the imprinted nanocomposite had higher adsorption ability for MO compared with the non-imprinted one. Moreover, it could degrade CR rapidly in dark at room temperature and atmospheric pressure and could be recycled easily by a magnet with a good reusability. A degradation mechanism was proposed according to LC–MS analysis of degradation products of CR. The new imprinted nanoparticles showed high catalytic activity at ambient conditions without light illumination and additional chemicals, and therefore, it can be potentially applied to the rapid, “green” and low-cost degradation of CR in industrial printing and dyeing wastewater.

Primary Dendrite Arm Spacings in Al-7Si Alloy Directionally Solidified on the International Space Station

Science.gov (United States)

Angart, Samuel; Lauer, Mark; Poirier, David; Tewari, Surendra; Rajamure, Ravi; Grugel, Richard

2015-01-01

Samples from directionally solidified Al- 7 wt. % Si have been analyzed for primary dendrite arm spacing (lambda) and radial macrosegregation. The alloy was directionally solidified (DS) aboard the ISS to determine the effect of mitigating convection on lambda and macrosegregation. Samples from terrestrial DS-experiments thermal histories are discussed for comparison. In some experiments, lambda was measured in microstructures that developed during the transition from one speed to another. To represent DS in the presence of no convection, the Hunt-Lu model was used to represent diffusion controlled growth under steady-state conditions. By sectioning cross-sections throughout the entire length of a solidified sample, lambda was measured and calculated using the model. During steady-state, there was reasonable agreement between the measured and calculated lambda's in the space-grown samples. In terrestrial samples, the differences between measured and calculated lambda's indicated that the dendritic growth was influenced by convection.

Microstructures and mechanical properties of grain refined Al-Li-Mg casting alloy by containing Zr and Ti

International Nuclear Information System (INIS)

Saikawa, Seiji; Nakai, Kiyoshi; Sugiura, Yasuo; Kamio, Akihiko.

1995-01-01

Mechanical properties and microstructures of various Al-Li-Mg alloy castings containing small amount of Zr and/or Ti were investigated. The δ(AlLi) phase was observed to crystallize in the dendrite-cell gaps as well as on the grain boundaries. Microsegregation of Mg also occurred in the solidified castings. The β(Al 3 Zr) or Al-Zr-Ti compounds crystallize during solidification and remain even after solid solution treatment at 803 K for 36 ks. The grain sizes of Al-2.5%Li-2%Mg alloy castings become finer by the addition of 0.15%Zr and 0.12%Ti compared with each addition of 0.15%Zr or 0.12%Ti. The age hardening is accelerated by the addition of 0.15%Zr. In an Al-2.5%Li-2%Mg-0.15%Zr-0.12%Ti alloy casting poured into a metallic mold and aged at 453 K for 36 ks, ultimate tensile strength, Young's modulus and density were 417 MPa, 80 GPa and was 2.52 g/cm 3 , respectively. Its specific strength and modulus are higher by 50.3 and 13.9% than those of the conventional AC4C-T6 casting. (author)

Leaching experiment of cement solidified waste form under unsaturated condition

International Nuclear Information System (INIS)

Wang Zhiming; Yao Laigen; Li Shushen; Zhao Yingjie; Cai Yun; Li Dan; Han Xinsheng; An Yongfeng

2003-01-01

A device for unsaturated leaching experiments was designed and built up. 8 different sizes, ranging from 40.2 cm 3 to 16945.5 cm 3 , of solidified waste form were tested in the experiment. 5 different water contents, from 0.15 to 0.40, were used for the experiment. The results show that the cumulative leaching fraction increases with water content when the sizes of the forms are equal to and less than 4586.7 cm 3 , for example, the ratios of the cumulative leaching fractions are between 1.24-1.41 under water content of 0.35 and 0.15 on 360 day of Teaching. It can also be seen that the cumulative leaching fraction under higher water content is close to that under saturated condition. The cumulative leaching fraction decreases with size of the form. Maximum leached depth of the solidified waste forms is about 2.25 cm after one year Teaching. Moreover, it has no clear effect on cumulative leaching fraction that sampling or non-sampling during the experiment

Structural heredity of TiC and its influences on refinement behaviors of AlTiC master alloy

Institute of Scientific and Technical Information of China (English)

王振卿; 刘相法; 柳延辉; 张均燕; 于丽娜; 边秀房

2003-01-01

Heredity of microstructure in AlTiC master alloy, grain refiners, was analyzed. It is found that, for morphologies and distributions of TiC particles, there are visible heredity which originates from raw materials or processing methods of Al melt, and will ultimately be transferred to the solid state structure through the melt stage, and this phenomenon can cause hereditary influences on refinement: formation of chain-like TiC morphology results in rapid refinement fading behavior; distribution of TiC along grain boundaries greatly reduces refinement efficiency. Controlling of structural heredity through proper selections of raw materials and processing parameters is of great importance in obtaining ideal microstructures and improving refinement behaviors of AlTiC master alloys.

Validation of the solidifying soil process using laser-induced breakdown spectroscopy

Science.gov (United States)

Lin, Zhao-Xiang; Liu, Lin-Mei; Liu, Lu-Wen

2016-09-01

Although an Ionic Soil Stabilizer (ISS) has been widely used in landslide control, it is desirable to effectively monitor the stabilization process. With the application of laser-induced breakdown spectroscopy (LIBS), the ion contents of K, Ca, Na, Mg, Al, and Si in the permeable fluid are detected after the solidified soil samples have been permeated. The processes of the Ca ion exchange are analyzed at pressures of 2 and 3 atm, and it was determined that the cation exchanged faster as the pressure increased. The Ca ion exchanges were monitored for different stabilizer mixtures, and it was found that a ratio of 1:200 of ISS to soil is most effective. The investigated plasticity and liquidity indexes also showed that the 1:200 ratio delivers the best performance. The research work indicates that it is possible to evaluate the engineering performances of soil solidified by ISS in real time and online by LIBS.

Method of solidifying radioactive wastes

International Nuclear Information System (INIS)

Maeda, Masahiko; Kira, Satoshi; Watanabe, Naotoshi; Nagaoka, Takeshi; Akane, Junta.

1982-01-01

Purpose: To obtain solidification products of radioactive wastes having sufficient monoaxial compression strength and excellent in water durability upon ocean disposal of the wastes. Method: Solidification products having sufficient strength and filled with a great amount of radioactive wastes are obtained by filling and solidifying 100 parts by weight of chlorinated polyethylene resin and 100 - 500 parts by weight of particular or powderous spent ion exchange resin as radioactive wastes. The chlorinated polyethylene resin preferably used herein is prepared by chlorinating powderous or particulate polyethylene resin in an aqueous suspending medium or by chlorinating polyethylene resin dissolved in an organic solvent capable of dissolving the polyethylene resin, and it is crystalline or non-crystalline chlorinated polyethylene resin comprising 20 - 50% by weight of chlorine, non-crystalline resin with 25 - 40% by weight of chlorine being particularly preferred. (Horiuchi, T.)

Ti and N adatom descent pathways to the terrace from atop two-dimensional TiN/TiN(001) islands

Energy Technology Data Exchange (ETDEWEB)

Edström, D., E-mail: daned@ifm.liu.se [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping (Sweden); Sangiovanni, D.G.; Hultman, L.; Chirita, V. [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping (Sweden); Petrov, I.; Greene, J.E. [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping (Sweden); Frederick Seitz Materials Research Laboratory and the Materials Science Department, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2014-05-02

We use classical molecular dynamics and the modified embedded atom method to determine residence times and descent pathways of Ti and N adatoms on square, single-atom-high, TiN islands on TiN(001). Simulations are carried out at 1000 K, which is within the optimal range for TiN(001) epitaxial growth. Results show that the frequency of descent events, and overall adatom residence times, depend strongly on both the TiN(001) diffusion barrier for each species as well as the adatom island-edge location immediately prior to descent. Ti adatoms, with a low diffusion barrier, rapidly move toward the island periphery, via funneling, where they diffuse along upper island edges. The primary descent mechanism for Ti adatoms is via push-out/exchange with Ti island-edge atoms, a process in which the adatom replaces an island edge atom by moving down while pushing the edge atom out onto the terrace to occupy an epitaxial position along the island edge. Double push-out events are also observed for Ti adatoms descending at N corner positions. N adatoms, with a considerably higher diffusion barrier on TiN(001), require much longer times to reach island edges and, consequently, have significantly longer residence times. N adatoms are found to descend onto the terrace by direct hopping over island edges and corner atoms, as well as by concerted push-out/exchange with N atoms adjacent to Ti corners. For both adspecies, we also observe several complex adatom/island interactions, before and after descent onto the terrace, including two instances of Ti island-atom ascent onto the island surface. - Highlights: • We use classical molecular dynamics to model Ti and N adatom migration on TiN(001) islands. • N adatoms remain on islands significantly longer than Ti adatoms. • Ti adatoms descend via push-out/exchange, N adatoms primarily by direct hops. • N adatoms act as precursors for multilayer formation and surface roughening.

Ti and N adatom descent pathways to the terrace from atop two-dimensional TiN/TiN(001) islands

International Nuclear Information System (INIS)

Edström, D.; Sangiovanni, D.G.; Hultman, L.; Chirita, V.; Petrov, I.; Greene, J.E.

2014-01-01

We use classical molecular dynamics and the modified embedded atom method to determine residence times and descent pathways of Ti and N adatoms on square, single-atom-high, TiN islands on TiN(001). Simulations are carried out at 1000 K, which is within the optimal range for TiN(001) epitaxial growth. Results show that the frequency of descent events, and overall adatom residence times, depend strongly on both the TiN(001) diffusion barrier for each species as well as the adatom island-edge location immediately prior to descent. Ti adatoms, with a low diffusion barrier, rapidly move toward the island periphery, via funneling, where they diffuse along upper island edges. The primary descent mechanism for Ti adatoms is via push-out/exchange with Ti island-edge atoms, a process in which the adatom replaces an island edge atom by moving down while pushing the edge atom out onto the terrace to occupy an epitaxial position along the island edge. Double push-out events are also observed for Ti adatoms descending at N corner positions. N adatoms, with a considerably higher diffusion barrier on TiN(001), require much longer times to reach island edges and, consequently, have significantly longer residence times. N adatoms are found to descend onto the terrace by direct hopping over island edges and corner atoms, as well as by concerted push-out/exchange with N atoms adjacent to Ti corners. For both adspecies, we also observe several complex adatom/island interactions, before and after descent onto the terrace, including two instances of Ti island-atom ascent onto the island surface. - Highlights: • We use classical molecular dynamics to model Ti and N adatom migration on TiN(001) islands. • N adatoms remain on islands significantly longer than Ti adatoms. • Ti adatoms descend via push-out/exchange, N adatoms primarily by direct hops. • N adatoms act as precursors for multilayer formation and surface roughening

Effect of iron and cerium additions on rapidly solidified Al-TM-Ce alloys

Czech Academy of Sciences Publication Activity Database

Michalcová, A.; Vojtěch, D.; Schumacher, G.; Novák, P.; Pližingrová, Eva

2013-01-01

Roč. 47, č. 6 (2013), s. 757-761 ISSN 1580-2949 Institutional support: RVO:61388980 Keywords : rapid solidification * aluminium * quasicrystals Subject RIV: CA - Inorganic Chemistry Impact factor: 0.555, year: 2013

Lamellar boundary alignment of DS-processed TiAl-W alloys by a solidification procedure

Science.gov (United States)

Jung, In-Soo; Oh, Myung-Hoon; Park, No-Jin; Kumar, K. Sharvan; Wee, Dang-Moon

2007-12-01

In this study, a β solidification procedure was used to align the lamellae in a Ti-47Al-2W (at.%) alloy parallel to the growth direction. The Bridgman technique and the floating zone process were used for directional solidification. The mechanical properties of the directionally solidified alloy were evaluated in tension at room temperature and at 800°C. At a growth rate of 30 mm/h (with the floating zone approach), the lamellae were well aligned parallel to the growth direction. The aligned lamellae yielded excellent room temperature tensile ductility. The tensile yield strength at 800°C was similar to that at room temperature. The orientation of the γ lamellar laths in the directionally solidified ingots, which were manufactured by means of a floating zone process, was identified with the aid of electron backscattered diffraction analysis. On the basis of this analysis, the preferred growth direction of the bcc-β dendrites that formed at high temperatures close to the melting point was inferred to be [001]β at a growth rate of 30 mm/h and [111]β at a growth rate of 90 mm/h.

Rapid charge-discharge property of Li4Ti5O12-TiO2 nanosheet and nanotube composites as anode material for power lithium-ion batteries.

Science.gov (United States)

Yi, Ting-Feng; Fang, Zi-Kui; Xie, Ying; Zhu, Yan-Rong; Yang, Shuang-Yuan

2014-11-26

Well-defined Li4Ti5O12-TiO2 nanosheet and nanotube composites have been synthesized by a solvothermal process. The combination of in situ generated rutile-TiO2 in Li4Ti5O12 nanosheets or nanotubes is favorable for reducing the electrode polarization, and Li4Ti5O12-TiO2 nanocomposites show faster lithium insertion/extraction kinetics than that of pristine Li4Ti5O12 during cycling. Li4Ti5O12-TiO2 electrodes also display lower charge-transfer resistance and higher lithium diffusion coefficients than pristine Li4Ti5O12. Therefore, Li4Ti5O12-TiO2 electrodes display lower charge-transfer resistance and higher lithium diffusion coefficients. This reveals that the in situ TiO2 modification improves the electronic conductivity and electrochemical activity of the electrode in the local environment, resulting in its relatively higher capacity at high charge-discharge rate. Li4Ti5O12-TiO2 nanocomposite with a Li/Ti ratio of 3.8:5 exhibits the lowest charge-transfer resistance and the highest lithium diffusion coefficient among all samples, and it shows a much improved rate capability and specific capacity in comparison with pristine Li4Ti5O12 when charging and discharging at a 10 C rate. The improved high-rate capability, cycling stability, and fast charge-discharge performance of Li4Ti5O12-TiO2 nanocomposites can be ascribed to the improvement of electrochemical reversibility, lithium ion diffusion, and conductivity by in situ TiO2 modification.

Growth and microstructure formation of isothermally-solidified Zircaloy-4 joints brazed by a Zr–Ti–Cu–Ni amorphous alloy ribbon

Energy Technology Data Exchange (ETDEWEB)

Kim, K.H. [University of Science and Technology, Nuclear Materials Development Division, Korea Atomic Energy Research Institute (KAERI), Yuseong, Daejeon 305-353 (Korea, Republic of); Lim, C.H. [Nuclear Materials Development Division, Korea Atomic Energy Research Institute (KAERI), Yuseong, Daejeon 305-353 (Korea, Republic of); Lee, J.G., E-mail: jglee88@kaeri.re.kr [Nuclear Materials Development Division, Korea Atomic Energy Research Institute (KAERI), Yuseong, Daejeon 305-353 (Korea, Republic of); Lee, M.K.; Rhee, C.K. [Nuclear Materials Development Division, Korea Atomic Energy Research Institute (KAERI), Yuseong, Daejeon 305-353 (Korea, Republic of)

2013-10-15

The microstructure and growth characteristics of Zircaloy-4 joints brazed by a Zr{sub 48}Ti{sub 16}Cu{sub 17}Ni{sub 19} (at.%) amorphous filler metal have been investigated with regard to the controlled isothermal solidification and intermetallic formation. Two typical joints were produced depending on the isothermal brazing temperature: (1) a dendritic growth structure including bulky segregation in the central zone (at 850 °C), and (2) a homogeneous dendritic structure throughout the joint without segregation (at 890 °C). The primary α-Zr phase was solidified isothermally, nucleating to grow into a joint with a cellular or dendritic structure. Also, the continuous Zr{sub 2}Ni and particulate Zr{sub 2}Cu phases were formed in the segregated center zone and at the intercellular region, respectively, owing to the different solubility and atomic mobility of the solute elements (Ti, Cu, and Ni) in the α-Zr matrix. A disappearance of the central Zr{sub 2}Ni phase was also rate-controlled by the outward diffusion of the Cu and Ni elements. When the detrimental Zr{sub 2}Ni intermetallic phase was eliminated by a complete isothermal solidification at 890 °C, the strengths of the joints were high enough to cause yielding and fracture in the base metal, exceeding those of the bulk Zircaloy-4, at room temperature as well as at elevated temperatures (up to 400 °C)

Application of plasma sprayed ceramic coatings to the base materials of the rotating disk in the centrifugal atomization process. Enshinryoku funmuho ni okeru kaiten enban eno ceramic yosha himaku no tekiyo

Energy Technology Data Exchange (ETDEWEB)

Sato, T; Okimoto, K [Government Industrial Research Inst., Kyushu, Tosu, Saga (Japan); Yasutake, R [Koeiseiko Co. Ltd., Fukuoka (Japan)

1992-07-08

Applicability of the ceramic coating on the rotating disk was studied. In regard to the synthesis of Cu-based rapidly solidified powders, centrifugal atomization with molten Cu-24.6Sn was carried out using rotating disks sprayed with four kinds of sprayed ceramic coatings. It was found that atomization of Al203-40%TiO2 sprayed coating has been the best, and the yield ratio has been about 60 %. The melt temperature in case of Fe-based rapidly solidified metal powders, has risen above 1600[degree]C, and the required conditions for rotating disk have been very difficult to meet. The reason for it is thought that there has also been limitations regarding the functions of the characteristics like heat transfer, heat capacity, etc. Fe-24Cr-5Ni-1Mo 2 phase stainless steel powder has shown the most suitable trend among the seven kinds of disk materials examined for ZrO2 ceramic sprayed coatings. 6 refs., 5 figs., 2 tabs.

Evaluating the freeze-thaw durability of portland cement-stabilized-solidified heavy metal waste using acoustic measurements

International Nuclear Information System (INIS)

El-Korchi, T.; Gress, D.; Baldwin, K.; Bishop, P.

1989-01-01

The use of stress wave propagation to assess freeze-thaw resistance of portland cement solidified/stabilized waste is presented. The stress wave technique is sensitive to the internal structure of the specimens and would detect structural deterioration independent of weight loss or visual observations. The freeze-thaw resistance of a cement-solidified cadmium waste and a control was evaluated. The control and cadmium wastes both showed poor freeze-thaw resistance. However, the addition of cadmium and seawater curing increased the resistance to more cycles of freezing and thawing. This is attributed to microstructural changes

Effectiveness of Ti-micro alloying in relation to cooling rate on corrosion of AZ91 Mg alloy

International Nuclear Information System (INIS)

Candan, S.; Celik, M.; Candan, E.

2016-01-01

In this study, micro Ti-alloyed AZ91 Mg alloys (AZ91 + 0.5wt.%Ti) have been investigated in order to clarify effectiveness of micro alloying and/or cooling rate on their corrosion properties. Molten alloys were solidified under various cooling rates by using four stage step mold. The microstructural investigations were carried out by using scanning electron microscopy (SEM). Corrosion behaviors of the alloys were evaluated by means of immersion and electrochemical polarization tests in 3.5% NaCl solution. Results showed that the Mg 17 Al 12 (β) intermetallic phase in the microstructure of AZ91 Mg alloy formed as a net-like structure. The Ti addition has reduced the distribution and continuity of β intermetallic phase and its morphology has emerged as fully divorced eutectic. Compared to AZ91 alloy, the effect of the cooling rate in Ti-added alloy on the grain size was less pronounced. When AZ91 and its Ti-added alloys were compared under the same cooling conditions, the Ti addition showed notably high corrosion resistance. Electrochemical test results showed that while I corr values of AZ91 decrease with the increase in the cooling rate, the effect of the cooling rate on I corr values was much lower in the Ti-added alloy. The corrosion resistance of AZ91 Mg alloy was sensitive towards the cooling rates while Ti-added alloy was not affected much from the cooling conditions. - Highlights: • Effect the cooling rate on grain size was less pronounced in the Ti-added alloy. • The morphology of the β phase transformed into fully divorced eutectics. • Ti addition exhibited significantly higher corrosion resistance. • Ti micro alloying is more effective than faster cooling of the alloy on corrosion.

Precipitation in as-solidified undercooled Ni-Si hypoeutectic alloy: Effect of non-equilibrium solidification

Energy Technology Data Exchange (ETDEWEB)

Fan Kai [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China); Liu Feng, E-mail: liufeng@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China); Yang Gencang; Zhou Yaohe [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China)

2011-08-25

Highlights: {yields} The solid solubility of Si atom in {alpha}-Ni matrix increased with undercooling in the as-solidified sample. {yields} The effect of non-equilibrium solidification on precipitation has been theoretically described. {yields} The nucleation density, the real-time particle size and the precipitation rate are all increased upon annealing. {yields} The precipitate process can be artificially controlled by modifying the initial melt undercooling and the annealing time. - Abstract: Applying glass fluxing and cyclic superheating, high undercooling up to {approx}350 K was achieved for Ni-Si hypoeutectic alloy melt. By isothermally annealing the as-solidified alloy subjected to different undercoolings, precipitation behavior of Ni{sub 3}Si particle, at 973 K, was systematically studied. It was found that, the nucleation density and the real-time particle size, as well as the precipitation rate, were all increased, provided the sample was solidified subjected to higher undercooling. This was ascribed mainly to the increased solid solubility of Si atom in {alpha}-Ni matrix upon non-equilibrium solidification. On this basis, the non-equilibrium dendrite growth upon solidification and the soft impingement prevailing upon solid-state precipitation have been quantitatively connected. As such, the effect of liquid/solid transformation on subsequent precipitation was described.

Precipitation in as-solidified undercooled Ni-Si hypoeutectic alloy: Effect of non-equilibrium solidification

International Nuclear Information System (INIS)

Fan Kai; Liu Feng; Yang Gencang; Zhou Yaohe

2011-01-01

Highlights: → The solid solubility of Si atom in α-Ni matrix increased with undercooling in the as-solidified sample. → The effect of non-equilibrium solidification on precipitation has been theoretically described. → The nucleation density, the real-time particle size and the precipitation rate are all increased upon annealing. → The precipitate process can be artificially controlled by modifying the initial melt undercooling and the annealing time. - Abstract: Applying glass fluxing and cyclic superheating, high undercooling up to ∼350 K was achieved for Ni-Si hypoeutectic alloy melt. By isothermally annealing the as-solidified alloy subjected to different undercoolings, precipitation behavior of Ni 3 Si particle, at 973 K, was systematically studied. It was found that, the nucleation density and the real-time particle size, as well as the precipitation rate, were all increased, provided the sample was solidified subjected to higher undercooling. This was ascribed mainly to the increased solid solubility of Si atom in α-Ni matrix upon non-equilibrium solidification. On this basis, the non-equilibrium dendrite growth upon solidification and the soft impingement prevailing upon solid-state precipitation have been quantitatively connected. As such, the effect of liquid/solid transformation on subsequent precipitation was described.

Cryogenic EBSD reveals structure of directionally solidified ice–polymer composite

Energy Technology Data Exchange (ETDEWEB)

Donius, Amalie E., E-mail: amalie.donius@gmail.com [Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 (United States); Department of Materials Science and Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Obbard, Rachel W., E-mail: Rachel.W.Obbard@dartmouth.edu [Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 (United States); Burger, Joan N., E-mail: ridge.of.the.ancients@gmail.com [Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 (United States); Department of Materials Science and Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Hunger, Philipp M., E-mail: philipp.m.hunger@gmail.com [Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 (United States); Department of Materials Science and Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Baker, Ian, E-mail: Ian.Baker@dartmouth.edu [Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 (United States); Doherty, Roger D., E-mail: dohertrd@drexel.edu [Department of Materials Science and Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Wegst, Ulrike G.K., E-mail: ulrike.wegst@dartmouth.edu [Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 (United States)

2014-07-01

Despite considerable research efforts on directionally solidified or freeze-cast materials in recent years, little fundamental knowledge has been gained that links model with experiment. In this contribution, the cryogenic characterization of directionally solidified polymer solutions illustrates, how powerful cryo-scanning electron microscopy combined with electron backscatter diffraction is for the structural characterization of ice–polymer composite materials. Under controlled sublimation, the freeze-cast polymer scaffold structure is revealed and imaged with secondary electrons. Electron backscatter diffraction fabric analysis shows that the ice crystals, which template the polymer scaffold and create the lamellar structure, have a-axes oriented parallel to the direction of solidification and the c-axes perpendicular to it. These results indicate the great potential of both cryo-scanning electron microscopy and cryo-electron backscatter diffraction in gaining fundamental knowledge of structure–property–processing correlations. - Highlights: • Cryo-SEM of freeze-cast polymer solution reveals an ice-templated structure. • Cryo-EBSD reveals the ice crystal a-axis to parallel the solidification direction. • The honeycomb-like polymer phase favors columnar ridges only on one side. • Combining cryo-SEM with EBSD links solidification theory with experiment.

Cryogenic EBSD reveals structure of directionally solidified ice–polymer composite

International Nuclear Information System (INIS)

Donius, Amalie E.; Obbard, Rachel W.; Burger, Joan N.; Hunger, Philipp M.; Baker, Ian; Doherty, Roger D.; Wegst, Ulrike G.K.

2014-01-01

Despite considerable research efforts on directionally solidified or freeze-cast materials in recent years, little fundamental knowledge has been gained that links model with experiment. In this contribution, the cryogenic characterization of directionally solidified polymer solutions illustrates, how powerful cryo-scanning electron microscopy combined with electron backscatter diffraction is for the structural characterization of ice–polymer composite materials. Under controlled sublimation, the freeze-cast polymer scaffold structure is revealed and imaged with secondary electrons. Electron backscatter diffraction fabric analysis shows that the ice crystals, which template the polymer scaffold and create the lamellar structure, have a-axes oriented parallel to the direction of solidification and the c-axes perpendicular to it. These results indicate the great potential of both cryo-scanning electron microscopy and cryo-electron backscatter diffraction in gaining fundamental knowledge of structure–property–processing correlations. - Highlights: • Cryo-SEM of freeze-cast polymer solution reveals an ice-templated structure. • Cryo-EBSD reveals the ice crystal a-axis to parallel the solidification direction. • The honeycomb-like polymer phase favors columnar ridges only on one side. • Combining cryo-SEM with EBSD links solidification theory with experiment

Influence of cooling rate and cerium addition on rapidly solidified Al-TM alloys

Czech Academy of Sciences Publication Activity Database

Michalcová, A.; Vojtěch, D.; Schumacher, G.; Novák, P.; Klementová, Mariana; Šerák, J.; Mudrová, M.; Valdaufová, J.

2010-01-01

Roč. 48, č. 1 (2010), s. 1-7 ISSN 0023-432X Institutional research plan: CEZ:AV0Z40320502 Keywords : rapid solidification * Al-TM * microstructure * aluminium Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.471, year: 2010

The dynamics of TiN{sub x} (x = 1–3) admolecule interlayer and intralayer transport on TiN/TiN(001) islands

Energy Technology Data Exchange (ETDEWEB)

Edström, D., E-mail: daned@ifm.liu.se [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping (Sweden); Sangiovanni, D.G.; Hultman, L. [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping (Sweden); Petrov, I.; Greene, J.E. [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping (Sweden); Frederick Seitz Materials Research Laboratory and the Materials Science Department, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Chirita, V. [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping (Sweden)

2015-08-31

It has been shown both experimentally and by density functional theory calculations that the primary diffusing species during the epitaxial growth of TiN/TiN(001) are Ti and N adatoms together with TiN{sub x} complexes (x = 1, 2, 3), in which the dominant N-containing admolecule species depends upon the incident N/Ti flux ratio. Here, we employ classical molecular dynamics (CMD) simulations to probe the dynamics of TiN{sub x} (x = 1–3) admolecules on 8 × 8 atom square, single-atom-high TiN islands on TiN(001), as well as pathways for descent over island edges. The simulations are carried out at 1000 K, a reasonable epitaxial growth temperature. We find that despite their lower mobility on infinite TiN(001) terraces, both TiN and TiN{sub 2} admolecules funnel toward descending steps and are incorporated into island edges more rapidly than Ti adatoms. On islands, TiN diffuses primarily via concerted translations, but rotation is the preferred diffusion mechanism on infinite terraces. TiN{sub 2} migration is initiated primarily by rotation about one of the N admolecule atoms anchored at an epitaxial site. TiN admolecules descend from islands by direct hopping over edges and by edge exchange reactions, while TiN{sub 2} trimers descend exclusively by hopping. In contrast, TiN{sub 3} admolecules are essentially stationary and serve as initiators for local island growth. Ti adatoms are the fastest diffusing species on infinite TiN(001) terraces, but on small TiN/TiN(001) islands, TiN dimers provide more efficient mass transport. The overall results reveal the effect of the N/Ti precursor flux ratio on TiN(001) surface morphological evolution and growth modes. - Highlights: • Classical MD is used to model TiN{sub x} admolecule dynamics on TiN/TiN(001) islands. • TiN{sub x} admolecules descend from islands by both direct hopping and exchange reactions. • TiN and TiN{sub 2} exhibit surprisingly high diffusivities on TiN/TiN(001) islands. • TiN{sub 3} tetramers are

Analysis of Light Gathering Abilities of Dynamically Solidified Micro-lenses, and Their Implementation to Improve Sensitivity of Fluorescent PCR Micro-detectors.

Science.gov (United States)

Wu, Jian; Guo, Wei; Wang, Chunyan; Yu, Kuanxin; Chen, Tao; Li, Yinghui

2015-06-01

Fluorescent polymerase chain reaction (PCR) is becoming the preferred method of quantitative analysis due to its high specificity and sensitivity. We propose to use a new kind of micro-lens, dynamically solidified with optic glue, to improve the sensitivity of fluorescent PCR micro-detector. We developed light ray track equations for these lenses and used them to calculate relative light intensity distribution curve for stimulation lenses and illumination point probability distribution curve for detection lenses. We manufactured dynamically solidified micro-lenses using optic glue NOA61, and measured their light gathering ability. Lenses with radius/thickness (R/H) ratio of 4 reached light focusing ratio of 3.85 (stimulation lens) and photon collection efficiency of 0.86 (detection lens). We then used dynamically solidified lenses in PCR fluorescence micro-detector and analyzed their effect on the detector sensitivity. We showed that the use of dynamically solidified micro-lenses with R/H = 4 resulted in over 4.4-fold increased sensitivity of the detector.

Long-term leach testing of solidified radioactive waste forms (International Standard Publication ISO 6961:1982)

International Nuclear Information System (INIS)

Stefanik, J.

2001-01-01

Processes are developed for the immobilization of radionuclides by solidification of radioactive wastes. The resulting solidification products are characterized by strong resistance to leaching aimed at low release rates of the radionuclides to the environment. To measure this resistance to leaching of the solidified materials: glass, glass-ceramics, bitumen, cement, concrete, plastics, a long-term leach test is presented. The long-term leach test is aimed at: a) the comparison of different kinds or compositions of solidified waste forms; b) the intercomparison between leach test results from different laboratories on one product; c) the intercomparison between leach test results on products from different processes

Lanthanum hexaboride as advanced structural refiner/getter in TiAl-based refractory intermetallics

Energy Technology Data Exchange (ETDEWEB)

Kartavykh, A.V., E-mail: karta@korolev-net.ru [Technological Institute for Superhard and Novel Carbon Materials (TISNCM), 7a Centralnaya str., 142190 Troitsk, Moscow (Russian Federation); National University of Science and Technology “MISIS”, Leninsky pr. 4, 119049 Moscow (Russian Federation); Asnis, E.A.; Piskun, N.V.; Statkevich, I.I. [The E.O. Paton Electric Welding Institute, 11 Bozhenko str., 03680 Kyiv (Ukraine); Gorshenkov, M.V.; Tcherdyntsev, V.V. [National University of Science and Technology “MISIS”, Leninsky pr. 4, 119049 Moscow (Russian Federation)

2014-03-05

Highlights: • Fist application of LaB{sub 6} additive in TiAl-based intermetallics casting. • Pilot synthesis/casting and study of selected TiAl(Nb,Cr,Zr)B,La alloys set. • Dual effect observed: phase structure refinement and oxygen impurity removal. • Co-precipitation of TiB and La{sub 2}O{sub 3} in melt: 2LaB{sub 6} + 12Ti + 3O → 12TiB↓ + La{sub 2}O{sub 3}↓. • Features of structure refinement and oxygen gettering mechanisms reported. -- Abstract: The work is aimed at the study of the formation and refinement of microstructure appearing in the solidifying refractory TiAl-based intermetallics being inoculated with precise boron addition. The novelty of research consists in test application of lanthanum hexaboride (LaB{sub 6}) ligature within semi-continuous electron beam casting process of selected alloys. Two ingots with nominal compositions Ti–44Al–5Nb–2Cr–1.5Zr–0.4B–0.07La and Ti–44Al–5Nb–1Cr–1.5Zr–1B–0.17La (at.%) have been synthesized and cast along with the reference alloy Ti–44Al–5Nb–3Cr–1.5Zr. Their comparative examination suggests (i) essential microstructural phase refinement effect coupled with (ii) threefold/fourfold decrease of background content of undesirable residual oxygen impurity in both alloys containing LaB{sub 6}. This advanced dual activity (i–ii) of LaB{sub 6} is explained by its complete dissolution, dissociation and following re-precipitation of effective Ti-based monoboride nucleants of orthorhombic B27 structure, those being accompanied by strong internal gettering of dissolved oxygen from the melt and from boride-inoculated solid α{sub 2}-Ti{sub 3}Al phase with liberated elemental lanthanum. The phase composition and structure of cast alloys; state and characterization of newly precipitated TiB boride; features of La{sub 2}O{sub 3} micro/nano-dimensional precipitation and oxygen gettering mechanism are reported and discussed.

Chemical characterization, leach, and adsorption studies of solidified low-level wastes

International Nuclear Information System (INIS)

Walter, M.B.; Serne, R.J.; Jones, T.L.; McLaurine, S.B.

1986-12-01

Laboratory and field leaching experiments are beig conducted by Pacific Northwest Laboratory (PNL) to investigate the performance of solidified low-level nuclear waste in a typical, arid, near-surface disposal site. Under PNL's Special Waste Form Lysimeters-Arid Program, a field test facility was constructed to monitor the leaching of commercial solidified waste. Laboratory experiments were conducted to investigate the leaching and adsorption characteristics of the waste forms in contact with soil. Liquid radioactive wastes solidified in cement, vinyl ester-styrene, and bitumen were obtained from commercial boiling water and pressurized water reactors, and buried in a field leaching facility on the Hanford site in southeastern Washington State. Batch leaching, soil column adsorption, and soil/waste form column experiments were conducted in the laboratory, using small-scale cement waste forms and Hanford site ground water. The purpose of these experiments is to evaluate the ability of laboratory leaching tests to predict leaching under actual field conditions and to determine which mechanisms (i.e., diffusion, solubility, adsorption) actually control the concentration of radionuclides in the soil surrounding the waste form. Chemical and radionuclide analyses performed on samples collected from the field and laboratory experiments indicate strong adsorption of /sup 134,137/Cs and 85 Sr onto the Hanford site sediment. Small amounts of 60 Co are leached from the waste forms as very mobile species. Some 60 Co migrated through the soil at the same rate as water. Chemical constituents present in the reactor waste streams also found at elevated levels in the field and laboratory leachates include sodium, sulfate, magnesium, and nitrate. Plausible solid phases that could be controlling some of the chemical and radionuclide concentrations in the leachate were identified using the MINTEQ geochemical computer code

Microbially influenced degradation of cement-solidified low-level radioactive waste forms

International Nuclear Information System (INIS)

Rogers, R.D.; Hamilton, M.A.; Veeh, R.H.; McConnell, J.W. Jr.

1996-01-01

Because of its apparent structural integrity, cement has been widely used in the United States as a binder to solidify Class B and C low-level radioactive waste (LLW). However, the resulting cement preparations are susceptible to failure due to the actions of stress and environment. This paper contains information on three groups of microoganisms that are associated with the degradation of cement materials: sulfur-oxidizing bacteria (Thiobacillus), nitrifying bacteria (Nitrosomonas and Nitrobacter), and heterotrophic bacteria, which produce organic acids. Preliminary work using laboratory- and vendor-manufactured, simulated waste forms exposed to thiobacilli has shown that microbiologically influenced degradation has the potential to severely compromise the structural integrity of ion-exchange resin and evaporator-bottoms waste that is solidified with cement. In addition, it was found that a significant percentage of calcium was leached from the treated waste forms. Also, the surface pH of the treated specimens was decreased to below 2. These conditions apparently contributed to the physical deterioration of simulated waste forms after 30 to 60 days of exposure

Research on the compressive strength of basic magnesium salts and cyanide slag solidified body

Science.gov (United States)

Tu, Yubo; Han, Peiwei; Ye, Shufeng; Wei, Lianqi; Zhang, Xiaomeng; Fu, Guoyan; Yu, Bo

2018-02-01

The solidification of cyanide slag by using basic magnesium salts could reduce pollution and protect the environment. Experiments were carried out to investigate the effects of age, mixing amount of cyanide slag, water cement ratio and molar ratio of MgO to MgSO4 on the compressive strength of basic magnesium salts and cyanide slag solidified body in the present paper. It was found that compressive strength of solidified body increased with the increase of age, and decreased with the increase of mixing amount of cyanide slag and water cement ratio. The molar ratio of MgO to MgSO4 should be controlled in the range from 9 to 11 when the mixing amount of cyanide slag was larger than 80 mass%.

Evolution of rapidly solidified NiAlCu(B) alloy microstructure.

Science.gov (United States)

Czeppe, Tomasz; Ochin, Patrick

2006-10-01

This study concerned phase transformations observed after rapid solidification and annealing at 500, 700 and 800 degrees C in 56.3 Ni-39.9 Al-3.8 Cu-0.06 B (E1) and 59.8 Ni-36.0 Al-4.3 Cu-0.06 B (E2) alloys (composition in at.%). Injection casting led to a homogeneous structure of very small, one-phase grains (2-4 microm in size). In both alloys, the phase observed at room temperature was martensite of L1(0) structure. The process of the formation of the Ni(5)Al(3) phase by atomic reordering proceeded at 285-394 degrees C in the case of E1 alloy and 450-550 degrees C in the case of E2 alloy. Further decomposition into NiAl (beta) and Ni(3)Al (gamma') phases, the microstructure and crystallography of the phases depended on the path of transformations, proceeding in the investigated case through the transformation of martensite crystallographic variants. This preserved precise crystallographic orientation between the subsequent phases, very stable plate-like morphology and very small beta + gamma' grains after annealing at 800 degrees C.

Hydrothermal–galvanic couple synthesis of directionally oriented BaTiO3 thin films on TiN-coated substrates

International Nuclear Information System (INIS)

Yang, Chia-Jung; Tsai, Di-You; Chan, Pei-Hsuan; Wu, Chu-Tsun; Lu, Fu-Hsing

2013-01-01

BaTiO 3 films were synthesized on TiN-coated Si substrate below 100 °C by a hydrothermal–galvanic couple technique in barium contained alkaline solutions. X-ray diffraction and electron backscatter diffraction results show that the BaTiO 3 thin films were directionally oriented grown on the TiN/Si substrates, i.e., (111) BaTiO 3 over (111) TiN. The surface morphologies revealed that BaTiO 3 nucleated and grew over the TiN surface with a single layer. From kinetic analyses, the growth rates of BaTiO 3 films prepared by the hydrothermal–galvanic couple technique were faster than a hydrothermal method. The galvanic effects were confirmed by investigating the induced currents and energies. The galvanic currents were generated and controlled by both the dissolution of TiN and the formation of BaTiO 3 . The output electric energies increased rapidly with the reaction time and leveled off at the full coverage of BaTiO 3 . - Highlights: • Cubic BaTiO 3 films are synthesized by a hydrothermal–galvanic couple method (HT–GC). • Growth rates of BaTiO 3 films made by HT–GC are faster than a hydrothermal method. • BaTiO 3 films are directionally oriented grown on the TiN/Si substrates. • Galvanic currents are controlled by dissolution of TiN and formation of BaTiO 3

Electrical characteristics and preparation of (Ba0.5Sr0.5)TiO3 films by spray pyrolysis and rapid thermal annealing

International Nuclear Information System (INIS)

Koo, Horngshow; Ku, Hongkou; Kawai, Tomoji; Chen Mi

2007-01-01

Functional films of (Ba 0.5 Sr 0.5 )TiO 3 on Pt (1000 A)/Ti (100 A)/SiO 2 (2000 A)/Si substrates are prepared by spray pyrolysis and subsequently rapid thermal annealing. Barium nitrate, strontium nitrate and titanium isopropoxide are used as starting materials with ethylene glycol as solvent. For (Ba 0.5 Sr 0.5 )TiO 3 functional thin film, thermal characteristics of the precursor powder scratched from as-sprayed films show a remarkable peak around 300-400degC and 57.7% weight loss up to 1000degC. The as-sprayed precursor film with coffee-like color and amorphous-like phase is transformed into the resultant film with white, crystalline perovskite phase and characteristic peaks (110) and (100). The resultant films show correspondent increases of dielectric constant, leakage current and dissipation factor with increasing annealing temperatures. The dielectric constant is 264 and tangent loss is 0.21 in the resultant films annealed at 750degC for 5 min while leakage current density is 1.5x10 -6 A/cm 2 in the film annealed at 550degC for 5 min. (author)

Development and characterization of solidified forms for high-level wastes: 1978. Annual report

International Nuclear Information System (INIS)

Ross, W.A.; Mendel, J.E.

1979-12-01

Development and characterization of solidified high-level waste forms are directed at determining both process properties and long-term behaviors of various solidified high-level waste forms in aqueous, thermal, and radiation environments. Waste glass properties measured as a function of composition were melt viscosity, melt electrical conductivity, devitrification, and chemical durability. The alkali metals were found to have the greatest effect upon glass properties. Titanium caused a slight decrease in viscosity and a significant increase in chemical durability in acidic solutions (pH-4). Aluminum, nickel and iron were all found to increase the formation of nickel-ferrite spinel crystals in the glass. Four multibarrier advanced waste forms were produced on a one-liter scale with simulated waste and characterized. Glass marbles encapsulated in a vacuum-cast lead alloy provided improved inertness with a minimal increase in technological complexity. Supercalcine spheres exhibited excellent inertness when coated with pyrolytic carbon and alumina and put in a metal matrix, but the processing requirements are quite complex. Tests on simulated and actual high-level waste glasses continue to suggest that thermal devitrification has a relatively small effect upon mechanical and chemical durabilities. Tests on the effects radiation has upon waste forms also continue to show changes to be relatively insignificant. Effects caused by decay of actinides can be estimated to saturate at near 10 19 alpha-events/cm 3 in homogeneous solids. Actually, in solidified waste forms the effects are usually observed around certain crystals as radiation causes amorphization and swelling of th crystals

Contribution to the study of U-Ti and U-Pu-Ti carbides; Contribution a l'etude des carbures U-C-Ti et (U, Pu) - C-Ti

Energy Technology Data Exchange (ETDEWEB)

Milet, C A [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-07-01

After having discussed the reasons to use (U,Pu) carbides as fast reactor fuel, we examine the influence of the addition of titanium to these carbides. A preliminary study has been done on the system of U-C-Ti and some properties have been measured such as: density, thermal expansion, electrical resistivity, atmospheric corrosion and compatibility with stainless steel. The systems U-Pu-C-Ti (Pu/U + Pu equal to 15 per cent) and U-C-Ti have been found to be very similar. There exists a two phases region (U,Pu)C + TiC, an eutectic between (U,Pu)C and TiC for approximately 15 at %. The solubilities of U + Pu in TiC and of Ti in (U,Pu)C is less than 1 % at. The addition of titanium does not markedly change thermal expansion coefficients of (U,Pu)C. However the resistance to atmospheric corrosion and compatibility with stainless steel is improved. Thermal conductivity, calculated from electrical resistivity, has increased. On the other side, the density of fissile material is lowered. The combination of (U,Pu)C + TiC seems to be the most promising alloy for application as nuclear fuel. (author) [French] Apres avoir rappele les problemes poses par un combustible pour les reacteurs a neutrons rapides et l'interet des carbures U-Pu-C comme combustible, on examine l'influence de l'addition de titane dans ces carbures. Une etude preliminaire sur le systeme U-C-Ti a ete effectuee et quelques proprietes sont indiquees: densite, coefficients de dilatation, resistivite electrique, tenue a la corrosion atmospherique, compatibilite avec l'acier inoxydable. Le systeme U-Pu-C-Ti (Pu/U + Pu egal a 15 pour cent) presente de grandes analogies avec le systeme U-C-Ti. Il existe un domaine biphase (U,Pu)C + TiC, un eutectique entre (U,Pu)C et TiC pour environ 15 at % Ti; les solubilites de U + Pu clans TiC et de Ti dans (U,Pu)C sont inferieures a 1 at %. Par rapport a la phase (U,Pu)C, l'addition de titane est sans effets importants sur les coefficients de dilatation. Par contre la tenue a

Testing of variables which affect stablity of cement solidified low-level waste

International Nuclear Information System (INIS)

Boris, G.F.

1989-01-01

This paper describes the test program undertaken to investigate variables which could affect the stability of cement solidified low-level waste and to evaluate the effect of these variables on certain tests prescribed in the Technical Position on Waste Form. The majority of the testing was performed on solidified undepleted bead resin, however, six additional waste types, suggested by the NRC, were tested. The tested variables included waste loading, immersion duration, depletion level, ambient cure duration, curing environment, immersion medium and waste type. Of these, lower waste loadings, longer ambient cures prior to testing and immersion in demineralized water versus simulated sea water and potable water resulted in higher compressive strengths for bead resin samples. Immersion times longer than 90 days did not affect the resin samples. Compressive strengths for other waste types varied depending upon the waste. The strengths of all waste types exceeded the minimum criterion by at least a factor of four, up to a factor of forty. The higher waste loadings exhibit strengths less than the lower waste loadings

Effect of rare-earth elements and quenching wheel speed on the structure, mechanical and thermal properties of rapidly solidified AZ91 Mg melt-spun ribbons

Energy Technology Data Exchange (ETDEWEB)

Ekrami, A. [Iran University of Industries & Mines, Faculty of Engineering & High-Technology (Iran, Islamic Republic of); Shahri, F., E-mail: fshahri@irost.ir [Iranian Research Organization for Science & Technology, Department of Advanced Materials & Renewable Energy (Iran, Islamic Republic of); Mirak, A. [Iran University of Industries & Mines, Faculty of Engineering & High-Technology (Iran, Islamic Republic of)

2017-01-27

In this work, an attempt is made to study the effects of rare-earth elements as an additive (2 wt% of Ce base misch-metal) and various quenching wheel speeds (10–40 m/s) on the microstructure, thermal and mechanical properties of rapidly solidified AZ91 alloy prepared by single roller melt-spinning process. In this respect, all of the samples were studied using various techniques such as x-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC) and mechanical properties such as microhardness and tensile tests. The finding bore witness to proposed hypothesis in this study illustrating due to high affinity between Al and RE by adding 2 wt% rare-earth elements in the AZ91alloy, thermally stable Al{sub x}RE{sub y} intermetallic compounds are precipitated and the formation of β-Mg{sub 17}Al{sub 12} phases is reduced. DSC results revealed that by adding RE to AZ91 alloy, AlRE phases got stable up to 500 °C, while for the AZ91 sample, β-Mg{sub 17}Al{sub 12} phase was formed at temperature about 180 °C and then with increasing of temperature dissolved at 410 °C in the α-Mg matrix. Further it has been observed that the higher was the quenching wheel speed, the smaller was the grain size which in turn gives rise to a higher tensile properties (from 406 MPa for quenching wheel speed of 10 m/s to 510 MPa for 40 m/s) for the MM-added alloys. Tensile strength of 386 MPa was obtained for the AZ91 pure alloy which is prepared at wheel speed of 40 m/sec.

Study on dissolution behavior of molten solidified waste

International Nuclear Information System (INIS)

Mizuno, Tsuyoshi; Maeda, Toshikatsu

2005-01-01

Radioactive molten solidified waste (slag) has been generated by melting non-metallic low-level radioactive wastes (LLW). Slag is expected to immobilize radionuclides in the waste repository. The chemical durability of slag is an important factor for the safety assessment of the disposal in that the durability provides the source term in the assessment. Since a chemical characteristic of slag is similar to that of glass, the general information on the chemical durability of slag might be provided from previous studies on nuclear waste glass. We have investigated effects of chemical compositions of slag and alkaline environments of repository on the chemical durability of slag. (author)

Structure of Cu-Ti brazing filler metal in amorphous and crystalline states

Energy Technology Data Exchange (ETDEWEB)

Maksymova, S; Khorunov, V [Paton Electric Welding Institute, NASU, 11 Bozhenko Str., Kyiv, 03680 (Ukraine); Zelinskaya, G [G.V. Kurdyumov Institute of Metal Physics, NASU, Kyiv, 03142 (Ukraine)], E-mail: maksymova@paton.kiev.ua

2008-02-15

Structure, chemical homogeneity and phase composition of rapidly quenched ribbons of brazing filler metal Ti{sub 57}Cu{sub 43} were investigated. The ribbons were found to be amorphous. The alloy components are uniformly distributed along the thickness of the strip. High-temperature differential thermal analysis was used to determine temperature ranges of the ribbons crystallization. X-ray diffraction analysis was performed to study phase composition of the rapidly quenched ribbons in the initial state and after their isothermal annealing. Two crystalline phases - {gamma}-CuTi and CuTi{sub 3} being identified in the latter case.

Study of directionally solidified eutectic Al2O3-ZrO2(3%Y2O3 doped with TiO2

Directory of Open Access Journals (Sweden)

Peña, J. I.

2007-06-01

Full Text Available An study of directionally grown samples of the eutectic composition in the Al2O3-ZrO2 (3 mol% Y2O3 system, with small TiO2 additions (1 wt%, is presented. The microstructural changes induced by this addition are analysed using SEM (EDX techniques. The mechanical changes, when TiO2 is added, are studied by measuring the flexural strength by three point bending. Also, the toughness is determined by Vickers indentation method. When slow growth rates (10 mm/h are used, interpenetratred and homogeneous microstructure is obtained, independently of the TiO2 doping. When growth rates are higher (300 and 1000 mm/h the structure changes and the phases are organized in form of colonies or cells, which have smaller size when TiO2 is present. This size reduction is accompanied with an increase of the toughness.Este trabajo presenta un estudio de muestras crecidas direccionalmente del sistema Al2O3-ZrO2 (3 mol% Y2O3 en su composición eutéctica con pequeñas adiciones de óxido de titanio (1% de TiO2 en peso. Se analizan los cambios microestructurales inducidos por esta adición mediante SEM (EDX y se estudian los cambios en su comportamiento mecánico medido por flexión en tres puntos, así como la tenacidad de fractura mediante indentación Vickers. Con velocidades lentas de solidificación (10 mm/h se obtiene en ambos casos una microestructura homogénea e interpenetrada, mientras que a velocidades mayores, 300 y 1000 mm/h, se forma una estructura en las que las fases se organizan en forma de colonias o células, siendo éstas de menor tamaño en las muestras dopadas. Esta disminución en el tamaño viene acompañada de un aumento de la tenacidad de fractura medida por indentación.

Method of solidifying radioactive liquid wastes

International Nuclear Information System (INIS)

Uetake, Naoto; Kawamura, Fumio; Kikuchi, Makoto; Fukazawa, Tetsuo.

1983-01-01

Purpose: To enable to confine the volatiling ingredients such as cesium in liquid wastes safely in glass solidification products while suppressing the volatilization thereof. Method: Acid salt of tetravalent metal such as titanium phosphate has an intense selective adsorption property to cesium. So liquid wastes stored in a high level liquid wastes tank is mixed with titanium phosphate gels stored in an adsorbent tank, then supplied to a mixer and mixed with a sodium silicate solution stored in a sodium silicate storage tank and boric acid stored in an additive tank, into gel-like state. The gel-like material thus formed is supplied to a drier. After being dried at a temperature of 200sup(o)C - 300sup(o)C, the material is melted under heating at a temperature of 1000sup(o)C - 1100sup(o)C, and then cooled to solidify. (Horiuchi, T.)

Leach testing of simulated ion-exchange resin waste solidified in cement

International Nuclear Information System (INIS)

Muurinen, A.K.; Uotila, P.I.; Ovaskainen, R.M.

Leach tests were carried out on ion-exchange resins solidified in cement. Three product mixtures, two isotopes and four leachants at two temperatures, were tested. The increase of resin content increased the leaching of Cs-137; the effect of silix admixture was negligible. The type of the leachant has a stronger influence on Co-60 than on Cs-137. The increase of temperature usually also increased leaching. (author)

Leaching behavior of cement solidified materials

International Nuclear Information System (INIS)

2002-03-01

An immersion test of mortar was carried out in order to solidify waste with uranium. The sample consists of 2000g cement, 950g ion exchange water, 1600g sound and 1g water reducing agent. The solid sample and ion exchange water (100 of immersion liquid/original sample) was put into polystyrene closed vessel in globe box and kept four weeks, and then it was separated to the immersion liquid and the solid phase. New ion exchange water was added to the solid and kept four weeks and then separated. Its ratio showed 200. The analysis was done at 100, 200 and 300 ratio of immersion liquid/sample. The solid phase was studied by the powder X-ray diffraction analysis, thermo gravimetric analysis and chemical analysis. The liquid phase was determined by pH values and composition analysis. The results showed Ca(OH) 2 , cement hydrate, was flowed out and it was not found in the solid phase at 200 ratio. (S.Y.)

Microstructure characterization of rapidly solidified Al-Fe-Cr-Ce alloy by positron annihilation spectroscopy

Czech Academy of Sciences Publication Activity Database

Michalcová, A.; Vojtěch, D.; Čízek, J.; Procházka, I.; Drahokoupil, Jan; Novák, P.

2011-01-01

Roč. 509, č. 7 (2011), s. 3211-3218 ISSN 0925-8388 Institutional research plan: CEZ:AV0Z10100520 Keywords : metals and alloy s * nanostructured materials * rapid solidification * positron spectroscopies * transmission electron microscopy * x-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.289, year: 2011

Glass forming in La2O3-TiO2-ZrO2 ternary system by containerless processing

Science.gov (United States)

Kaneko, Masashi; Kentei Yu, Yu; Kumar, Vijaya; Masuno, Atsunobu; Inoue, Hiroyuki; Odawara, Osamu; Yoda, Shinichi

The containerless processing is an appropriate method to create new glasses, because it sup-presses nucleation at the boundary between liquid and crucible during solidification and it enables molten samples to be solidified without crystallization. Recently, we have succeeded in forming BaTi2 O5 glass in the bulk state by using an aerodynamic levitation furnace. BaTi2 O5 glass includes no traditional glass network former and it possesses high electric permittivity [1, 2]. From the point of view of optical application, BaTi2 O5 glass has high refractive indices over 2.1. BaTi2 O5 glass, however, vitrify only in a small sphere, and it crystallize when its diameter exceed 1.5 mm. In order to synthesize new titanate oxide glasses which possess higher refractive indices and larger diameter than BaTi2 O5 , La and Zr can be used as substitutive components. When Ba is replaced with La, refractive indices are expected to increase because of the heavier element. The addition of a third element is thought to be effective for enhance-ment of glass formation ability and Zr can be a candidate because Ti and Zr are homologous. In this research, we have succeeded in forming new bulk glass in La2 O3 -TiO2 -ZrO2 ternary system by means of the aerodynamic levitation furnace. We investigated the glass forming region, thermal properties and optical properties of La2 O3 -TiO2 -ZrO2 glass. Glass transition temperature, crystallization temperature, density, refractive indices and transmittance spectra were varied depending on the chemical composition. Reference [1] J. Yu et al, "Fabrication of BaTi2O5 Glass-Ceramics with Unusual Dielectric Properties during Crystallization", Chem-istry of Materials, 18 (2006) 2169-2173. [2] J. Yu et al., "Comprehensive Structural Study of Glassy and Metastable Crystalline BaTi2O5", Chemistry of Materials, 21 (2009) 259-263.

The Role of Phase Changes in TiO2/Pt/TiO2 Filaments

Science.gov (United States)

Bíró, Ferenc; Hajnal, Zoltán; Dücső, Csaba; Bársony, István

2018-04-01

This work analyses the role of phase changes in TiO2/Pt/TiO2 layer stacks for micro-heater application regarding their stability and reliable operation. The polycrystalline Pt layer wrapped in a TiO2 adhesion layer underwent a continuous recrystallisation in a self-heating operation causing a drift in the resistance ( R) versus temperature ( T) performance. Simultaneously, the TiO2 adhesion layer also deteriorates at high temperature by phase changes from amorphous to anatase and rutile crystallite formation, which not only influences the Pt diffusion in different migration phenomena, but also reduces the cross section of the Pt heater wire. Thorough scanning electron microscopy, energy dispersive spectroscopy, cross-sectional transmission electron microscopy (XTEM) and electron beam diffraction analysis of the structures operated at increasing temperature revealed the elemental structural processes leading to the instabilities and the accelerated degradation, resulting in rapid breakdown of the heater wire. Owing to stability and reliability criteria, the conditions for safe operation of these layer structures could be determined.

Microstructure and tribological properties of TiAg intermetallic compound coating

International Nuclear Information System (INIS)

Guo Chun; Chen Jianmin; Zhou Jiansong; Zhao Jierong; Wang Linqian; Yu Youjun; Zhou Huidi

2011-01-01

TiAg intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding using Ag powder as the precursor. It has been found that the prepared coating mainly comprised TiAg and Ti phases. The high resolution transmission electron microscopy results further conform the existence of TiAg intermetallic compound in the prepared coating. The magnified high resolution transmission electron microscopy images shown that the laser cladding coating contains TiAg nanocrystalline with the size of about 4 nm. Tribological properties of the prepared TiAg intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiAg intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiAg intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate increased as the normal load increased.

Microstructure and tribological properties of TiAg intermetallic compound coating

Energy Technology Data Exchange (ETDEWEB)

Guo Chun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Chen Jianmin, E-mail: chenjm@lzb.ac.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhou Jiansong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhao Jierong; Wang Linqian; Yu Youjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Zhou Huidi [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2011-10-01

TiAg intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding using Ag powder as the precursor. It has been found that the prepared coating mainly comprised TiAg and Ti phases. The high resolution transmission electron microscopy results further conform the existence of TiAg intermetallic compound in the prepared coating. The magnified high resolution transmission electron microscopy images shown that the laser cladding coating contains TiAg nanocrystalline with the size of about 4 nm. Tribological properties of the prepared TiAg intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiAg intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiAg intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate increased as the normal load increased.

A process for solidifying radioactive liquid waste

International Nuclear Information System (INIS)

Mergan, L.M.; Cordier, J.-P.

1981-01-01

In a process for solidifying radioactive liquid waste, its pH is adjusted, solids precipitated and then it is concentrated to about 50% solids content using a thin film evaporator, the concentrate then being dried to powder in a heated mixer. The mixer has a heated wall and working means, e.g. a rotor and helical screw, to shear the dried concentrate from the internal walls, subdivide it into a dry particulate powder, and advance the powder to the mixer outlet. The dried particles are then encapsulated in a suitable matrix. Vapour from the mixer and evaporator is condensed and recycled after any particles have been removed from it. The mixer may both dry the concentrate and mix the dry particles with the encapsulating matrix, and possibly, part of the mixer may be used for pH adjustment and precipitation. (author)

PIIID-formed (Ti, O)/Ti, (Ti, N)/Ti and (Ti, O, N)/Ti coatings on NiTi shape memory alloy for medical applications

Energy Technology Data Exchange (ETDEWEB)

Sun Tao, E-mail: taosun@hotmail.com.hk [Department of Mechanical Engineering, University of Hong Kong, Pokfulam Road (Hong Kong); Institute of Microelectronics, Agency for Science, Technology and Research (A-STAR) (Singapore); Wang Langping, E-mail: aplpwang@hit.edu.cn [State Key Lab of Advanced Welding and Joining, Harbin Institute of Technology (China); Wang Min; Tong Howang [Department of Mechanical Engineering, University of Hong Kong, Pokfulam Road (Hong Kong); Lu, William W. [Department of Orthopedics and Traumatology, University of Hong Kong, Sassoon Road (Hong Kong)

2012-08-01

(Ti, O)/Ti, (Ti, N)/Ti and (Ti, O, N)/Ti composite coatings were fabricated on NiTi shape memory alloy via plasma immersion ion implantation and deposition (PIIID). Surface morphology of samples was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Cross-sectional morphology indicated that the PIIID-formed coatings were dense and uniform. X-ray diffraction (XRD) was used to characterize the phase composition of samples. X-ray photoelectron spectroscopy (XPS) results showed that the surface of coated NiTi SMA samples was Ni-free. Nanoindentation measurements and pin-on-disc tests were carried out to evaluate mechanical properties and wear resistance of coated NiTi SMA, respectively. For the in vitro biological assessment of the composite coatings in terms of cell morphology and cell viability, osteoblast-like SaOS-2 cells and breast cancer MCF-7 cells were cultured on NiTi SMA samples, respectively. SaOS-2 cells attached and spread better on coated NiTi SMA. Viability of MCF-7 cells showed that the PIIID-formed composite coatings were noncytotoxic and coated samples were more biocompatible than uncoated samples. - Highlights: Black-Right-Pointing-Pointer PIIID-formed coatings were fabricated on NiTi SMA to improve its biocompatibility. Black-Right-Pointing-Pointer Microstructure, mechanical properties and biocompatibility of coatings were investigated. Black-Right-Pointing-Pointer All PIIID-formed composite coatings were noncytotoxic and cytocompatible.

Performance criteria for solidified high-level radioactive wastes. Environmental impact statement. Revision 1

International Nuclear Information System (INIS)

1977-09-01

This draft Environmental Impact Statement on performance criteria for solidified high-level radioactive wastes (PCSHLW) covers: considerations for PCSHLW development, the proposed rulemaking, characteristics of the PCSHLW, environmental impacts of the proposed PCSHLW, alternatives to the PCSHLW criteria, and cost/benefit/risk evaluation. Five appendices are included to support the technical data required in the Environmental Impact Statement

Detection of free liquid in containers of solidified radioactive waste

Science.gov (United States)

Greenhalgh, W.O.

Nondestructive detection of the presence of free liquid within a sealed enclosure containing solidified waste is accomplished by measuring the levels of waste at two diametrically opposite locations while slowly tilting the enclosure toward one of said locations. When the measured level remains constant at the other location, the measured level at said one location is noted and any measured difference of levels indicates the presence of liquid on the surface of the solifified waste. The absence of liquid in the enclosure is verified when the measured levels at both locations are equal.

Self-Consolidation Mechanism of Nanostructured Ti5Si3 Compact Induced by Electrical Discharge

Directory of Open Access Journals (Sweden)

W. H. Lee

2015-01-01

Full Text Available Electrical discharge using a capacitance of 450 μF at 7.0 and 8.0 kJ input energies was applied to mechanical alloyed Ti5Si3 powder without applying any external pressure. A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge. During an electrical discharge, the heat generated is the required parameter possibly to melt the Ti5Si3 particles and the pinch force can pressurize the melted powder without allowing the formation of pores. Followed rapid cooling preserved the nanostructure of consolidated Ti5Si3 compact. Three stepped processes during an electrical discharge for the formation of nanostructured Ti5Si3 compact are proposed: (a a physical breakdown of the surface oxide of Ti5Si3 powder particles, (b melting and condensation of Ti5Si3 powder by the heat and pinch pressure, respectively, and (c rapid cooling for the preservation of nanostructure. Complete conversion yielding a single phase Ti5Si3 is primarily dominated by the solid-liquid mechanism.

Rapid synthesis of Ti-MCM-41 by microwave-assisted hydrothermal method towards photocatalytic degradation of oxytetracycline.

Science.gov (United States)

Chen, Hanlin; Peng, Yen-Ping; Chen, Ku-Fan; Lai, Chia-Hsiang; Lin, Yung-Chang

2016-06-01

This study employed microwave-assisted hydrothermal method to synthesize Ti-MCM-41, which are mesoporous materials with a high surface area and excellent photocatalytic ability. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV-Vis) were employed. The XRD findings showed that Ti-MCM-41 exhibited a peak at 2θ of 2.2°, which was attributed to the hexagonal MCM-41 structure. The BET (Brunauer-Emmett-Teller) results agreed with the TEM findings that Ti-MCM-41 has a pore size of about 3-5nm and a high surface area of 883m(2)/g. FTIR results illustrated the existence of Si-O-Si and Si-O-Ti bonds in Ti-MCM-41. The appearance of Ti 2p peaks in the XPS results confirmed the FTIR findings that the Ti was successfully doped into the MCM-41 structure. Zeta (ζ)-potential results indicated that the iso-electric point (IEP) of Ti-MCM-41 was at about pH3.02. In this study, the photocatalytic degradation of oxytetracycline (OTC) at different pH was investigated under Hg lamp irradiation (wavelength 365nm). The rate constant (K'obs) for OTC degradation was 0.012min(-1) at pH3. Furthermore, TOC (total organic carbon) and high resolution LC-MS (liquid chromatography-mass spectrometry) analyses were conducted to elucidate the possible intermediate products and degradation pathway for OTC. The TOC removal efficiency of OTC degradation was 87.0%, 74.4% and 50.9% at pH3, 7 and 10, respectively. LC-MS analysis results showed that the degradation products from OTC resulted from the removal of functional groups from the OTC ring. Copyright © 2016. Published by Elsevier B.V.

Elevated temperature mechanical properties of a rapidly solidified A1-Fe-V-Si alloy

International Nuclear Information System (INIS)

Mitra, S.

1992-01-01

Dispersion strengthened Al alloys based on the Al-Fe-V-Si quartenary system have recently been developed using rapid solidification techniques. Rapid solidification techniques which resulted in the above mentioned alloys have also been used to manufacture another commercial alloy, FVS 1212, with 37 volume % of dispersoid. The alloy has shown excellent resistance to coarsening at high temperatures and to creep deformation. Elevated temperature exposure of FVS 1212, for times up to 100 hours, resulted in a significant loss in room temperature mechanical properties only beyond 500 degrees C while 1000 hours at 425 degrees C did not result in any degradation of mechanical but no detailed study of the tensile behavior of FVS 1212 at slow strain rates and elevated temperatures has been reported to date. This paper reports that the present study was undertaken to investigate the tensile behavior of FVS 1212 from room temperature to 400 degrees C at strain rates of 6.56 x 10 - 5/sec and 6.56 x 10 -6 /sec. The study focussed on dynamic strain aging effects and strain hardening behavior, while the effect of strain rate on the flow behavior at elevated temperatures was also evaluated

Water Adsorption on TiO2

DEFF Research Database (Denmark)

Hammer, Bjørk; Wendt, Stefan; Besenbacher, Flemming

2010-01-01

Scanning Tunneling Microscopy (STM) studies and Density Functional Theory (DFT) investigations of the interaction of water with the rutile TiO2 (110) surface are summarized. From high-resolution STM the following reactions have been revealed: water adsorption and diffusion in the Ti troughs, water...... dissociation in bridging oxygen vacancies, assembly of adsorbed water monomers into rapidly diffusing water dimers, and formation of water dimers by reduction of oxygen molecules. The STM results are rationalized based on DFT calculations, revealing the bonding geometries and reaction pathways of the water...

Freckle Defect Formation near the Casting Interfaces of Directionally Solidified Superalloys.

Science.gov (United States)

Hong, Jianping; Ma, Dexin; Wang, Jun; Wang, Fu; Sun, Baode; Dong, Anping; Li, Fei; Bührig-Polaczek, Andreas

2016-11-16

Freckle defects usually appear on the surface of castings and industrial ingots during the directional solidification process and most of them are located near the interface between the shell mold and superalloys. Ceramic cores create more interfaces in the directionally solidified (DS) and single crystal (SX) hollow turbine blades. In order to investigate the location of freckle occurrence in superalloys, superalloy CM247 LC was directionally solidified in an industrial-sized Bridgman furnace. Instead of ceramic cores, Alumina tubes were used inside of the casting specimens. It was found that freckles occur not only on the casting external surfaces, but also appear near the internal interfaces between the ceramic core and superalloys. Meanwhile, the size, initial position, and area of freckle were investigated in various diameters of the specimens. The initial position of the freckle chain reduces when the diameter of the rods increase. Freckle area follows a linear relationship in various diameters and the average freckle fraction is 1.1% of cross sectional area of casting specimens. The flow of liquid metal near the interfaces was stronger than that in the interdendritic region in the mushy zone, and explained why freckle tends to occur on the outer or inner surfaces of castings. This new phenomenon suggests that freckles are more likely to occur on the outer or inner surfaces of the hollow turbine blades.

Freckle Defect Formation near the Casting Interfaces of Directionally Solidified Superalloys

Directory of Open Access Journals (Sweden)

Jianping Hong

2016-11-01

Full Text Available Freckle defects usually appear on the surface of castings and industrial ingots during the directional solidification process and most of them are located near the interface between the shell mold and superalloys. Ceramic cores create more interfaces in the directionally solidified (DS and single crystal (SX hollow turbine blades. In order to investigate the location of freckle occurrence in superalloys, superalloy CM247 LC was directionally solidified in an industrial-sized Bridgman furnace. Instead of ceramic cores, Alumina tubes were used inside of the casting specimens. It was found that freckles occur not only on the casting external surfaces, but also appear near the internal interfaces between the ceramic core and superalloys. Meanwhile, the size, initial position, and area of freckle were investigated in various diameters of the specimens. The initial position of the freckle chain reduces when the diameter of the rods increase. Freckle area follows a linear relationship in various diameters and the average freckle fraction is 1.1% of cross sectional area of casting specimens. The flow of liquid metal near the interfaces was stronger than that in the interdendritic region in the mushy zone, and explained why freckle tends to occur on the outer or inner surfaces of castings. This new phenomenon suggests that freckles are more likely to occur on the outer or inner surfaces of the hollow turbine blades.

IAEA coordinated research program on the evaluation of solidified high-level radioactive waste products

International Nuclear Information System (INIS)

Grover, J.R.; Schneider, K.J.

1979-01-01

A coordinated research program on the evaluation of solidified high-level radioactive waste products has been active with the IAEA since 1976. The program's objectives are to integrate research and to provide a data bank on an international basis in this subject area. Results and considerations to date are presented

Study of vibrational and rapid local motions of hydrogen in the storage compound Ti0.8 Zr0.2 CrMnH3 by slow neutron scattering

International Nuclear Information System (INIS)

Mestnik Filho, J.

1987-01-01

The vibrational and the rapid local motions of hydrogen in the storage compound Ti 0,8 Zr 0,2 CrMnH 3 have been studied by slow neutron scattering with the beryllium-filter-time-of-flight spectrometer. The form of the density of states of the normal modes of vibrations in host metal does no appear to change on hydrogenation, but a shift of 25% towards lower frequencies has been observed. Debye temperatures for the metal and corresponding hydride have been estimated to be respectively (522 +- 15)K and (311 +- 10)K. An energy distribution consisting of three peeks ∼ 50mev (FWHM) wide corresponding to the energy transfer of 85, 115 and 141mev has been observed and were attributed to hydrogen local vibrations in three types of interstices wich differs in composition of Ti and Zr atoms. In the quasielastic scattering, a broadening of 15μev has been detected for the momentum transfer Q = 2,1(angstrom) -1 and for temperature T= 125 0 C. The broadening has been attributed to rapid local motions of hydrogen in a dumb-bell of lenght equal to the jump lenght for diffusion, l approx. 3(angstrom). (author) [pt

Microstructure of Fe-Cr-C hardfacing alloys with additions of Nb, Ti and, B

International Nuclear Information System (INIS)

Berns, H.; Fischer, A.

1987-01-01

The abrasive wear of machine parts and tools used in the mining, earth moving, and transporting of mineral materials can be lowered by filler wire welding of hardfacing alloys. In this paper, the microstructures of Fe-Cr-C and Fe-Cr-C-Nb/Ti hardfacing alloys and deposits and those of newly developed Fe-Cr-C-B and Fe-Ti-Cr-C-B ones are described. They show up to 85 vol.% of primarily solidified coarse hard phases; i.e., Carbides of MC-, M/sub 7/C/sub 3/-, M/sub 3/C-type and Borides of MB/sub 2/-, M/sub 3/B/sub 2/-, M/sub 2/B-, M/sub 3/B-, M/sub 23/B/sub 6/-type, which are embedded in a hard eutectic. This itself consists of eutectic hard phases and a martensitic or austenitic metal matrix. The newly developed Fe-Cr-C-B alloys reach hardness values of up to 1200 HV and are harder than all purchased ones. The primary solidification of the MB/sub 2/-type phase of titanium requires such high amounts of titanium and boron that these alloys are not practical for manufacture as commercial filler wires

Microstructure, Wear Resistance and Oxidation Behavior of Ni-Ti-Si Coatings Fabricated on Ti6Al4V by Laser Cladding

Directory of Open Access Journals (Sweden)

Qiaoqiao Zhuang

2017-10-01

Full Text Available The Ni-Ti-Si composite coatings were successfully fabricated on Ti6Al4V by laser cladding. The microstructure were studied by SEM (scanning electron microscopy and EDS (energy dispersive spectrometer. It has been found that Ti2Ni and Ti5Si3 phases exist in all coatings, and some samples have TiSi2 phases. Moreover, due to the existence of these phases, coatings presented relatively higher microhardness than that of the substrate (826 HV (Vickers hardness and the microhardness value of coating 3 is about twice larger than that of the substrate. During the dry sliding friction and wear test, due to the distribution of the relatively ductile phase of Ti2Ni and reinforcement phases of Ti5Si3 and TiSi2, the coatings performed good wear resistance. The oxidation process contains two stages: the rapid oxidation and slow oxidation by high temperature oxidation test at 800 °C for 50 h. Meanwhile, the value of the oxidation weight gain of the substrate is approximately three times larger than that of the coating 4. During the oxidation process, the oxidation film formed on the coating is mainly consisted of TiO2, Al2O3 and SiO2. Phases Ti2Ni, Ti5Si3, TiSi2 and TiSi were still found and it could be responsible for the improvement in oxidation resistance of the coatings by laser cladding.

Effect of tensile mean stress on fatigue behavior of single-crystal and directionally solidified superalloys

Science.gov (United States)

Kalluri, Sreeramesh; Mcgaw, Michael A.

1990-01-01

Two nickel base superalloys, single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf, were studied in view of the potential usage of the former and usage of the latter as blade materials for the turbomachinery of the space shuttle main engine. The baseline zero mean stress (ZMS) fatigue life (FL) behavior of these superalloys was established, and then the effect of tensile mean stress (TMS) on their FL behavior was characterized. At room temperature these superalloys have lower ductilities and higher strengths than most polycrystalline engineering alloys. The cycle stress-strain response was thus nominally elastic in most of the fatigue tests. Therefore, a stress range based FL prediction approach was used to characterize both the ZMS and TMS fatigue data. In the past, several researchers have developed methods to account for the detrimental effect of tensile mean stress on the FL for polycrystalline engineering alloys. However, the applicability of these methods to single crystal and directionally solidified superalloys has not been established. In this study, these methods were applied to characterize the TMS fatigue data of single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf and were found to be unsatisfactory. Therefore, a method of accounting for the TMS effect on FL, that is based on a technique proposed by Heidmann and Manson was developed to characterize the TMS fatigue data of these superalloys. Details of this method and its relationship to the conventionally used mean stress methods in FL prediction are discussed.

A study of phase transformation in a TiAlNb alloy and the effect of Cr addition

Energy Technology Data Exchange (ETDEWEB)

Kesler, Michael S.; Goyel, Sonalika; Rios, Orlando [University of Florida, Materials Science and Engineering, P.O. Box 116400, Gainesville, FL 32611 (United States); Cupid, Damian M. [University of Florida, Materials Science and Engineering, P.O. Box 116400, Gainesville, FL 32611 (United States); Freiberg University of Mining and Technology, Institute of Materials Science, Freiberg (Germany); Seifert, Hans J. [Freiberg University of Mining and Technology, Institute of Materials Science, Freiberg (Germany); Ebrahimi, Fereshteh, E-mail: febra@mse.ufl.edu [University of Florida, Materials Science and Engineering, P.O. Box 116400, Gainesville, FL 32611 (United States)

2010-05-15

The phase transformation paths, transformation temperatures and phase equilibria of Ti-45Al-27Nb and Ti-45Al-22Nb-5Cr (at%) alloys were evaluated over a temperature range from 865 deg. C to 1600 deg. C. Both alloys solidified as single {beta}-phase and transformed to {gamma} + {sigma} phases upon slow cooling. The addition of Cr did not affect the {beta} {yields} {gamma} transformation temperature upon slow cooling. In contrast, the temperature, at which the {sigma}-phase formed, was reduced noticeably. Upon heating, the temperature at which the {beta}-phase evolves from the {gamma} + {sigma} microstructure was found to decrease significantly with the addition of Cr. In the ternary alloy the formation of the {gamma}-phase could not be retarded on quenching, however, the substitution of Nb with Cr allowed for the retainment of the {beta}-phase to room temperature. These results are explained by the partitioning of Cr into the {beta}-phase, which in addition to thermodynamic stability reduces the kinetics of transformations at lower temperatures.

A study of phase transformation in a TiAlNb alloy and the effect of Cr addition

Energy Technology Data Exchange (ETDEWEB)

Kesler, Michael [University of Florida, Gainesville; Goyel, Sonalika [University of Florida, Gainesville; Rios, Orlando [ORNL; Cupid, Damian M [Freiberg University of Mining and Technology; Seifert, Hans J [Freiberg University of Mining and Technology; Ebrahimi, Fereshteh [University of Florida, Gainesville

2010-01-01

The phase transformation paths, transformation temperatures and phase equilibria of Ti-45Al-27Nb and Ti-45Al-22Nb-5Cr (at%) alloys were evaluated over a temperature range from 865 C to 1600 C. Both alloys solidified as single {beta}-phase and transformed to {gamma} + {sigma} phases upon slow cooling. The addition of Cr did not affect the {beta} {yields} {gamma} transformation temperature upon slow cooling. In contrast, the temperature, at which the {sigma}-phase formed, was reduced noticeably. Upon heating, the temperature at which the {beta}-phase evolves from the {gamma} + {sigma} microstructure was found to decrease significantly with the addition of Cr. In the ternary alloy the formation of the {gamma}-phase could not be retarded on quenching, however, the substitution of Nb with Cr allowed for the retainment of the {beta}-phase to room temperature. These results are explained by the partitioning of Cr into the {beta}-phase, which in addition to thermodynamic stability reduces the kinetics of transformations at lower temperatures.

A study of phase transformation in a TiAlNb alloy and the effect of Cr addition

International Nuclear Information System (INIS)

Kesler, Michael S.; Goyel, Sonalika; Rios, Orlando; Cupid, Damian M.; Seifert, Hans J.; Ebrahimi, Fereshteh

2010-01-01

The phase transformation paths, transformation temperatures and phase equilibria of Ti-45Al-27Nb and Ti-45Al-22Nb-5Cr (at%) alloys were evaluated over a temperature range from 865 deg. C to 1600 deg. C. Both alloys solidified as single β-phase and transformed to γ + σ phases upon slow cooling. The addition of Cr did not affect the β → γ transformation temperature upon slow cooling. In contrast, the temperature, at which the σ-phase formed, was reduced noticeably. Upon heating, the temperature at which the β-phase evolves from the γ + σ microstructure was found to decrease significantly with the addition of Cr. In the ternary alloy the formation of the γ-phase could not be retarded on quenching, however, the substitution of Nb with Cr allowed for the retainment of the β-phase to room temperature. These results are explained by the partitioning of Cr into the β-phase, which in addition to thermodynamic stability reduces the kinetics of transformations at lower temperatures.

Radiochemical analysis of homogeneously solidified low level radioactive waste from nuclear power plants

International Nuclear Information System (INIS)

Sato, Kaneaki; Ikeuchi, Yoshihiro; Higuchi, Hideo

1995-01-01

As mentioned above, we have reliable radioanalytical methods for all kinds of homogeneously solidified wastes. We are now under studying an analytical method for pellets which are made from evaporator concentrates or resin. And we are going to study to establish new analytical method for the rad-waste including metal, cloths and so on in near future. (J.P.N.)

Phase stability in wear-induced supersaturated Al-Ti solid solution

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Y.; Yokoyama, K. [Dept. of Functional Machinery Mechanics Shinshu Univ., Ueda (Japan); Hosoda, H. [Precision and Intelligence Lab., Tokyo Inst. of Tech., Nagatsuta, Midori-ku, Yokohama (Japan)

2002-07-01

Al-Ti supersaturated solid solutions were introduced by wear testing and the rapid quenching of an Al/Al{sub 3}Ti composite (part of an Al/Al{sub 3}Ti functionally graded material) that was fabricated using the centrifugal method. The phase stability of the supersaturated solid solution was studied through systematic annealing of the supersaturated solid solution. It was found that the Al-Ti supersaturated solid solution decomposed into Al and Al{sub 3}Ti intermetallic compound phases during the heat treatment. The Al-Ti supersaturated solid solutions fabricated were, therefore, not an equilibrium phase, and thus decomposed into the equilibrium phases during heat treatment. It was also found that heat treatment leads to a significant hardness increase for the Al-Ti supersaturated solid solution. Finally, it was concluded that formation of the wear-induced supersaturated solid solution layer was a result of severe plastic deformation. (orig.)

Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part II. Intermetallic Coarsening Behavior of Rapidly Solidified Solders After Multiple Reflows

Science.gov (United States)

Reeve, Kathlene N.; Choquette, Stephanie M.; Anderson, Iver E.; Handwerker, Carol A.

2016-12-01

Controlling the size, dispersion, and stability of intermetallic compounds in lead-free solder alloys is vital to creating reliable solder joints regardless of how many times the solder joints are melted and resolidified (reflowed) during circuit board assembly. In this article, the coarsening behavior of Cu x Al y and Cu6Sn5 in two Sn-Cu-Al alloys, a Sn-2.59Cu-0.43Al at. pct alloy produced via drip atomization and a Sn-5.39Cu-1.69Al at. pct alloy produced via melt spinning at a 5-m/s wheel speed, was characterized after multiple (1-5) reflow cycles via differential scanning calorimetry between the temperatures of 293 K and 523 K (20 °C and 250 °C). Little-to-no coarsening of the Cu x Al y particles was observed for either composition; however, clustering of Cu x Al y particles was observed. For Cu6Sn5 particle growth, a bimodal size distribution was observed for the drip atomized alloy, with large, faceted growth of Cu6Sn5 observed, while in the melt spun alloy, Cu6Sn5 particles displayed no significant increase in the average particle size, with irregularly shaped, nonfaceted Cu6Sn5 particles observed after reflow, which is consistent with shapes observed in the as-solidified alloys. The link between original alloy composition, reflow undercooling, and subsequent intermetallic coarsening behavior was discussed by using calculated solidification paths. The reflowed microstructures suggested that the heteroepitaxial relationship previously observed between the Cu x Al y and the Cu6Sn5 was maintained for both alloys.

Advanced powder metallurgy aluminum alloys via rapid solidification technology

Science.gov (United States)

Ray, R.

1984-01-01

Aluminum alloys containing 10 to 11.5 wt. pct. of iron and 1.5 to 3 wt. pct. of chromium using the technique of rapid solidification powder metallurgy were studied. Alloys were prepared as thin ribbons (.002 inch thick) rapidly solidified at uniform rate of 10(6) C/second by the melt spinning process. The melt spun ribbons were pulverized into powders (-60 to 400 mesh) by a rotating hammer mill. The powders were consolidated by hot extrusion at a high reduction ratio of 50:1. The powder extrusion temperature was varied to determine the range of desirable processing conditions necessary to yield useful properties. Powders and consolidated alloys were characterized by SEM and optical metallography. The consolidated alloys were evaluated for (1) thermal stability, (2) tensile properties in the range, room temperature to 450 F, and (3) notch toughness in the range, room temperature to 450 F.

Development of methodology to evaluate microbially influenced degradation of cement-solidified low-level radioactive waste forms

International Nuclear Information System (INIS)

Rogers, R.D.; Hamilton, M.A.; Veeh, R.H.; McConnell, J.W.

1994-01-01

Because of its apparent structural integrity, cement has been widely used in the United States as a binder to solidify Class B and C low-level radioactive waste (LLW). However, the resulting cement preparations are susceptible to failure due to the actions of stress and environment. An environmentally mediated process that could affect cement stability is the action of naturally occurring microorganisms. The US Nuclear Regulatory Commission (NRC), recognizing this eventuality, stated that the effects of microbial action on waste form integrity must be addressed. This paper provides present results from an ongoing program that addresses the effects of microbially influenced degradation (MID) on cement-solidified LLW. Data are provided on the development of an evaluation method using acid-producing bacteria. Results are from work with one type of these bacteria, the sulfur-oxidizing Thiobacillus. This work involved the use of a system in which laboratory- and vendor-manufactured, simulated waste forms were exposed on an intermittent basis to media containing thiobacilli. Testing demonstrated that MID has the potential to severely compromise the structural integrity of ion-exchange resin and evaporator-bottoms waste that is solidified with cement. In addition, it was found that a significant percentage of calcium and other elements were leached from the treated waste forms. Also, the surface pH of the treated specimens decreased to below 2. These conditions apparently contributed to the physical deterioration of simulated waste forms after 60 days of exposure to the thiobacilli

Structure fields in the solidifying cast iron roll

Directory of Open Access Journals (Sweden)

W.S. Wołczyński

2010-01-01

Full Text Available Some properties of the rolls depend on the ratio of columnar structure area to equiaxed structure area created during roll solidification. The transition is fundamental phenomenon that can be apply to characterize massive cast iron rolls produced by the casting house. As the first step of simulation, a temperature field for solidifying cast iron roll was created. The convection in the liquid is not comprised since in the first approximation, the convection does not influence the studied occurrence of the (columnar to equiaxed grains transition in the roll. The obtained temperature field allows to study the dynamics of its behavior observed in the middle of the mould thickness. This midpoint of the mould thickness was treated as an operating point for the transition. A full accumulation of the heat in the mould was postulated for the transition. Thus, a plateau at the curve was observed at the midpoint. The range of the plateau existence corresponded to the incubation period , that appeared before fully equiaxed grains formation. At the second step of simulation, behavior of the thermal gradients field was studied. Three ranges within the filed were visible: EC→EC→EC→EC→(tTECtt↔RERCtt↔a/ for the formation of columnar structure (the C – zone: ( and 0>>T&0>>=−>−=REREttGttG.The columnar structure formation was significantly slowed down during incubation period. It resulted from a competition between columnar growth and equiaxed growth expected at that period of time. The 0≈=−=RERCttGttG relationship was postulated to correspond well with the critical thermal gradient, known in the Hunt’s theory. A simulation was performed for the cast iron rolls solidifying as if in industrial condition. Since the incubation divides the roll into two zones: C and E; (the first with columnar structure and the second with fully equiaxed structure some experiments dealing with solidification were made on semi-industrial scale.

A novel solidified floating organic drop microextraction method for preconcentration and determination of copper ions by flow injection flame atomic absorption spectrometry

International Nuclear Information System (INIS)

Sahin, Cigdem Arpa; Tokgoez, Ilknur

2010-01-01

A rapid, simple and cost effective solidified floating organic drop microextraction (SFODME) and flow injection flame atomic absorption spectrometric determination (FI-FAAS) method for copper was developed. In this method, a free microdrop of 1-undecanol containing 1,5-diphenyl carbazide (DPC) as the complexing agent was transferred to the surface of an aqueous sample including Cu(II) ions, while being agitated by a stirring bar in the bulk of the solution. Under the proper stirring conditions, the suspended microdrop can remain at the top-center position of the aqueous sample. After the completion of the extraction, the sample vial was cooled by placing it in a refrigerator for 10 min. The solidified microdrop was then transferred into a conical vial, where it melted immediately and diluted to 300 μL with ethanol. Finally, copper ions in 200 μL of diluted solution were determined by FI-FAAS. Several factors affecting the microextraction efficiency, such as type of extraction solvent, pH, complexing agent concentration, extraction time, stirring rate, sample volume and temperature were investigated and optimized. Under optimized conditions for 100 mL of solution, the preconcentration factor was 333 and the enrichment factor was 324. The limit of detection (3 s) was 0.4 ng mL -1 , the limit of quantification (10 s) was 1.1 ng mL -1 and the relative standard deviation (RSD) for 10 replicate measurements of 10 ng mL -1 copper was 0.9%. The proposed method was successfully applied to the determination of copper in different water samples.

Effect of grain refiner on intermetallic phase formation in directional solidification of 6xxx series wrought Al alloys

Energy Technology Data Exchange (ETDEWEB)

Sha, G.; O' Reilly, K.; Cantor, B. [Oxford Univ. (United Kingdom). Centre for Adv. Mat. and Composites; Hamerton, R.; Worth, J.

2000-07-01

The effect of a grain refiner on the formation of intermetallic phases in a directionally solidified (Bridgman grown) model 6xxx series wrought Al alloy has been investigated using X-ray diffractometry (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). A base alloy with and without Al-Ti-B grain refiner was directionally solidified in a Bridgman furnace at growth velocities in the range of 5-120 mm/min. In both cases, the Fe-containing intermetallic phases present were found to be mainly {alpha}-AlFeSi and {beta}-AlFeSi. However, in the alloy with grain refiner solidified at 5mm/min, Al{sub 13}Fe{sub 4} was also observed. Quantitative XRD results indicated that the addition of Al-Ti-B grain refiner has a strong influence on the relative quantities of intermetallic phases forming during solidification at different growth velocities, which was also confirmed by TEM observations. TEM observations also show that depending on where the {beta}-AlFeSi particles solidified e.g. grain boundaries or triple grain junctions, the size and morphology of the particles may change dramatically. TiB{sub 2} particles were observed to nucleate {beta}-AlFeSi at low and high growth velocities in the 6xxx series Al alloys. (orig.)

Experimental Study and Application of Inorganic Solidified Foam Filling Material for Coal Mines

Directory of Open Access Journals (Sweden)

Hu Wen

2017-01-01

Full Text Available Spontaneous combustion of residual coal in a gob due to air leakage poses a major risk to mining safety. Building an airtight wall is an effective measure for controlling air leakage. A new type of inorganic solidified foam-filled material was developed and its physical and chemical properties were analyzed experimentally. The compressive strength of this material increased with the amount of sulphoaluminate cement. With an increasing water–cement ratio, the initial setting time was gradually extended while the final setting time firstly shortened and then extended. The change in compressive strength had the opposite tendency. Additionally, as the foam expansion ratio increased, the solidification time tended to decrease but the compressive strength remained approximately constant. With an increase in foam production, the solidification time increased and the compressive strength decreased exponentially. The results can be used to determine the optimal material ratios of inorganic solidified foam-filled material for coal mines, and filling technology for an airtight wall was designed. A field application of the new material demonstrated that it seals crossheadings tightly, leaves no fissures, suppresses air leakage to the gob, and narrows the width of the spontaneous combustion and heat accumulation zone.

Determination of performance criteria for high-level solidified nuclear waste

Energy Technology Data Exchange (ETDEWEB)

Heckman, R.A.; Holdsworth, T.

1979-05-07

To minimize radiological risk from the operation of a waste management system, performance limits on volatilization, particulate dispersion, and dissolution characteristics of solidified high level waste must be specified. The results show clearly that the pre-emplacement environs are more limiting in establishing the waste form performance criteria than the post-emplacement environs. Absolute values of expected risk are very sensitive to modeling assumptions. The transportation and interim storage operations appear to be most limiting in determining the performance characteristics required. The expected values of risk do not rely upon the repositories remaining intact over the potentially hazardous lifetime of the waste.

Determination of performance criteria for high-level solidified nuclear waste

International Nuclear Information System (INIS)

Heckman, R.A.; Holdsworth, T.

1979-01-01

To minimize radiological risk from the operation of a waste management system, performance limits on volatilization, particulate dispersion, and dissolution characteristics of solidified high level waste must be specified. The results show clearly that the pre-emplacement environs are more limiting in establishing the waste form performance criteria than the post-emplacement environs. Absolute values of expected risk are very sensitive to modeling assumptions. The transportation and interim storage operations appear to be most limiting in determining the performance characteristics required. The expected values of risk do not rely upon the repositories remaining intact over the potentially hazardous lifetime of the waste

Mechanical behavior and related microstructural aspects of a nano-lamellar TiAl alloy at elevated temperatures

International Nuclear Information System (INIS)

Klein, T.; Usategui, L.; Rashkova, B.; Nó, M.L.; San Juan, J.; Clemens, H.; Mayer, S.

2017-01-01

Advanced intermetallic γ-TiAl based alloys, which solidify via the disordered β phase, such as the TNM"+ alloy, are considered as most promising candidates for structural applications at high temperatures in aero and automotive industries, where they are applied increasingly. Particularly creep resistant microstructures required for high-temperature application, i.e. fine fully lamellar microstructures, can be attained via two-step heat-treatments. Thereby, an increasing creep resistance is observed with decreasing lamellar interface spacing. Once lamellar structures reach nano-scaled dimensions, deformation mechanisms are altered dramatically. Hence, this study deals with a detailed characterization of the elevated temperature deformation phenomena prevailing in nano-lamellar TiAl alloys by the use of tensile creep experiments and mechanical spectroscopy. Upon creep exposure, microstructural changes occur in the lamellar structure, which are analyzed by the comparative utilization of X-ray diffraction, scanning and transmission electron microscopy as well as atom probe tomography. Creep activation parameters determined by mechanical characterization suggest the dominance of dislocation climb by a jog-pair formation process. The dislocations involved in deformation are, in nano-lamellar TiAl alloys, situated at the lamellar interfaces. During creep exposure the precipitation of β_o phase and ζ-silicide particles is observed emanating from the α_2 phase, which is due to the accumulation of Mo and Si at lamellar interfaces.

Leachability of radionuclides from cement solidified waste forms produced at operating nuclear power plants

International Nuclear Information System (INIS)

Croney, S.T.

1985-03-01

This study determined the leachability indexes of radionuclides contained in solidified liquid wastes from operating nuclear power plants. Different sizes of samples of cement-solidified liquid wastes were collected from two nuclear power plants - a pressurized water reactor and a boiling water reactor - to correlate radionuclide leaching from small- and full-sized (55-gallon) waste forms. Diffusion-based model analysis (ANS 16.1) of measured radionuclide leach data from both small- and full-sized samples was performed and indicate that leach data from small samples can be used to determine leachability indexes for full-sizes waste forms. The leachability indexes for cesium, strontium, and cobalt isotopes were determined for waste samples from both plants according to the models used for ANS 16.1. The leachability indexes for the pressurized water reactor samples were 6.4 for cesium, 7.1 for strontium, and 10.4 for cobalt. Leachability indexes for the boiling water reactor samples were 6.5 for cesium, 8.6 for strontium, and 11.1 for cobalt

Effective hydrogen diffusion coefficient for solidifying aluminium alloys

International Nuclear Information System (INIS)

Felberbaum, M.; Landry-Desy, E.; Weber, L.; Rappaz, M.

2011-01-01

An effective hydrogen diffusion coefficient has been calculated for two solidifying Al - 4.5 wt.% Cu and Al - 10 wt.% Cu alloys as a function of the volume fraction of solid. For this purpose, in situ X-ray tomography was performed on these alloys. For each volume fraction of solid between 0.6 and 0.9, a representative volume element of the microstructure was extracted. Solid and liquid voxels were assimilated to solid and liquid nodes in order to solve the hydrogen diffusion equation based on the chemical potential and using a finite volume formulation. An effective hydrogen diffusion coefficient based on the volume fraction of solid only could be deduced from the results of the numerical model at steady state. The results are compared with various effective medium theories.

Leaching test of bituminized waste and waste solidified by epoxy resin

International Nuclear Information System (INIS)

Yoshinaka, Kazuyuki; Sugaya, Atsushi; Onizawa, Toshikazu; Takano, Yugo; Kimura, Yukihiko

2008-10-01

About 30,000 bituminized waste drums and about 1800 drums of waste solidified by epoxy resin, generated from Tokai Reprocessing Plant, were stored in storage facilities. And study for disposal of these waste is performed. It was considered that radioactive nuclides and chemical components were released from these waste by contact of underground water, when disposed there waste. This paper is reported that result of leaching tests for these waste, done from 2003 to 2006. We've get precious knowledge and data, as follows. (1) In leaching tests for bituminized waste, it has detected iodine-129 peak, considered difficult too low energy gamma to detect. We've get data and knowledge of iodine-129 behavior first. Leached radioactivity for 50 days calculated by peak area was equal for about 40% and 100% of including radioactivity in bituminized waste sample. And we've get data of behavior of nitric acid ion and so on, important to study for disposal, in various condition of sample shape or leaching liquid temperature. (2) In leaching test for waste solidified by epoxy resin, we've get data of behavior of TBP, radionuclides and so on, important to study for disposal. Leached TBP was equal about 1% of including of sample. And we've get data of iodine-129 behavior, too. It was confirmed that leached iodine-129 was equal for about 60% and 100% of including sample, for 90 days. (author)

Nanomechanical properties of TiCN and TiCN/Ti coatings on Ti prepared by Filtered Arc Deposition

International Nuclear Information System (INIS)

Sun, Yong; Lu, Cheng; Yu, Hailiang; Kiet Tieu, A.; Su, Lihong; Zhao, Yue; Zhu, Hongtao; Kong, Charlie

2015-01-01

Monolayer TiCN and multilayer TiCN/Ti coatings were deposited on the surface of Ti using the Filtered Arc Deposition System (FADS). Nanoindentation tests were performed on both coatings. The multilayer TiCN/Ti coating exhibited better ductility than the monolayer TiCN coating. The lattice constants of the coatings were characterized by X-ray diffraction. Transmission Electron Microscopy (TEM) was used to investigate the fracture behavior of the coatings. Inter-columnar, inclined and lateral cracks were found to be the dominant crack modes in the monolayer TiCN coatings while small bending crack and radial crack were the dominant crack modes in the multilayer TiCN/Ti coatings. The Finite Element Method (FEM) was used to simulate the indentation process. It was found that the Ti interlayer in the multilayer TiCN/Ti coating could efficiently suppress the fracture, which is responsible for the improved ductility of the multilayer TiCN/Ti coating

Method of solidifying radioactive waste by plastics

International Nuclear Information System (INIS)

Yasumura, Keijiro; Tomita, Toshihide.

1976-01-01

Purpose: To prevent leakage of radioactivity by providing corrosion-resistant layer on the inner surface of a waste container for radioactive waste. Constitution: The inner periphery and bottom of a drum can is lined with an non-flammable cloth of such material as asbestos. This drum is filled with a radioactive waste in the form of powder or pellets. Then, a mixture of a liquid plastic monomer and a polymerization starting agent is poured at a normal temperature, and the surface is covered with a non-flammable cloth. The plastic monomer and radioactive waste are permitted to impregnate the non-flammable cloth and are solidified there. Thus, even if the drum can is corroded at the sea bottom after disposal it in the ocean, it is possible to prevent the waste from permeating into the outer sea water because of the presence of the plastic layer on the inside. Styrene is used as the monomer. (Aizawa, K.)

Method for accelerated leaching of solidified waste

International Nuclear Information System (INIS)

Fuhrmann, M.; Heiser, J.H.; Pietrzak, R.F.; Franz, E.M.; Colombo, P.

1990-11-01

An accelerated leach test method has been developed to determine the maximum leachability of solidified waste. The approach we have taken is to use a semi-dynamic leach test; that is, the leachant is sampled and replaced periodically. Parameters such as temperature, leachant volume, and specimen size are used to obtain releases that are accelerated relative to other standard leach tests and to the leaching of full-scale waste forms. The data obtained with this test can be used to model releases from waste forms, or to extrapolate from laboratory-scale to full-scale waste forms if diffusion is the dominant leaching mechanism. Diffusion can be confirmed as the leaching mechanism by using a computerized mathematical model for diffusion from a finite cylinder. We have written a computer program containing several models including diffusion to accompany this test. The program and a Users' Guide that gives screen-by-screen instructions on the use of the program are available from the authors. 14 refs., 4 figs., 1 tab

The effectiveness of Ti implants as barriers to carbon diffusion in Ti implanted steel under CVD diamond deposition conditions

Energy Technology Data Exchange (ETDEWEB)

Weiser, P.S.; Prawer, S. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Hoffman, A. [Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Chemistry; Evan, P.J. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Paterson, P.J.K. [Royal Melbourne Inst. of Tech., VIC (Australia)

1993-12-31

The growth of chemical vapour deposited (CVD) diamond onto iron based substrates complicated by preferential soot formation and carbon diffusion into the substrate [1], leading to poor quality films and poor adhesion. In the initial stages of exposure to a microwave plasma, a layer of graphite is rapidly formed on an untreated Fe based substrate. Once this graphite layer reaches a certain thickness, reasonable quality diamond nucleates and grows upon it. However, the diamond film easily delaminates from the substrate, the weak link being the graphitic layer. Following an initial success in using a TiN barrier layer to inhibit the formation of such a graphitic layer the authors report on attempts to use an implanted Ti layer for the same purpose. This work was prompted by observation that, although the TiN proved to be an extremely effective diffusion barrier, adhesion may be further enhanced by the formation of a TiC interface layer between the diamond film and the Fe substrate. 3 refs., 6 figs.

The effectiveness of Ti implants as barriers to carbon diffusion in Ti implanted steel under CVD diamond deposition conditions

International Nuclear Information System (INIS)

Weiser, P.S.; Prawer, S.; Paterson, P.J.K.

1993-01-01

The growth of chemical vapour deposited (CVD) diamond onto iron based substrates complicated by preferential soot formation and carbon diffusion into the substrate [1], leading to poor quality films and poor adhesion. In the initial stages of exposure to a microwave plasma, a layer of graphite is rapidly formed on an untreated Fe based substrate. Once this graphite layer reaches a certain thickness, reasonable quality diamond nucleates and grows upon it. However, the diamond film easily delaminates from the substrate, the weak link being the graphitic layer. Following an initial success in using a TiN barrier layer to inhibit the formation of such a graphitic layer the authors report on attempts to use an implanted Ti layer for the same purpose. This work was prompted by observation that, although the TiN proved to be an extremely effective diffusion barrier, adhesion may be further enhanced by the formation of a TiC interface layer between the diamond film and the Fe substrate. 3 refs., 6 figs

The effectiveness of Ti implants as barriers to carbon diffusion in Ti implanted steel under CVD diamond deposition conditions

Energy Technology Data Exchange (ETDEWEB)

Weiser, P S; Prawer, S [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Hoffman, A [Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Chemistry; Evan, P J [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Paterson, P J.K. [Royal Melbourne Inst. of Tech., VIC (Australia)

1994-12-31

The growth of chemical vapour deposited (CVD) diamond onto iron based substrates complicated by preferential soot formation and carbon diffusion into the substrate [1], leading to poor quality films and poor adhesion. In the initial stages of exposure to a microwave plasma, a layer of graphite is rapidly formed on an untreated Fe based substrate. Once this graphite layer reaches a certain thickness, reasonable quality diamond nucleates and grows upon it. However, the diamond film easily delaminates from the substrate, the weak link being the graphitic layer. Following an initial success in using a TiN barrier layer to inhibit the formation of such a graphitic layer the authors report on attempts to use an implanted Ti layer for the same purpose. This work was prompted by observation that, although the TiN proved to be an extremely effective diffusion barrier, adhesion may be further enhanced by the formation of a TiC interface layer between the diamond film and the Fe substrate. 3 refs., 6 figs.

Nanoscale dynamic wetting and spreading of molten Ti alloy on 6H-SiC

International Nuclear Information System (INIS)

Tanaka, Shun-Ichiro; Iwamoto, Chihiro

2008-01-01

We have investigated nanoscale features at the reactive wetting front of the molten Ag-27.4 wt.% Cu-4.9 wt.% Ti on 6H-SiC using video movies recorded in situ on a high-temperature stage of a high-resolution transmission electron microscope and also proposed a model of a chemical reaction at each tip. One of the features of reactive wetting and spreading at 1073 K in 4 x 10 -5 Pa was the discontinuous motion of the tip, and the halting time depended on the thickness of an amorphous Si-O layer on SiC, which can be explained by the time needed for the decomposition of the layer by Ti atoms to form TiC nanoparticles since Ti atoms in the molten alloy sufficiently rapidly diffuse to the tip on the SiC surface. Molten Ti and TiC nanolayers preceded the Ti 5 Si 3 nanolayer at the tip. The reaction required to form the TiC nanolayer is also the rate-determining step for spreading. The contact angle of the tip increased up to 60-80 deg. when the tip halted, whereas the tip decreased down to 10 deg. on the nonbasal plane and 20 deg. on the basal plane of SiC when it traveled rapidly. The high traveling angle of the molten tip on the basal polar plane of SiC indicates a high interfacial energy between Ti and SiC(0 0 0 1)

First-principles study on ferrite/TiC heterogeneous nucleation interface

International Nuclear Information System (INIS)

Yang, Jian; Zhang, Pengfei; Zhou, Yefei; Guo, Jing; Ren, Xuejun; Yang, Yulin; Yang, Qingxiang

2013-01-01

Highlights: ► Interface stability of ferrite (1 0 0)/TiC (1 0 0) was studied. ► The effectiveness of TiC as the heterogeneous nuclei of ferrite was analyzed. ► Ti-termination and C-termination are the two binding modes for ferrite/TiC interface. ► Interfacial energy of the Ti-termination is larger than that of the C-termination. ► On C-termination, ability of TiC promotes ferrite heterogeneous nucleation is strong. -- Abstract: Interface atomic structure, bonding character, cohesive energy and interfacial energy of ferrite (1 0 0)/TiC (1 0 0) were studied using a first-principles density functional plane-wave ultrasoft pseudopotential method. Meanwhile, the effectiveness of TiC as the heterogeneous nuclei of ferrite was analyzed. The results indicated that, TiC bonding is dominated by the C-2p, C-2s and Ti-3d electrons, which exhibits high covalency. With increase of the atomic layers, the interfacial energies of ferrite and TiC are both declined rapidly and stabilized gradually. There are two binding modes for TiC as the heterogeneous nuclei of ferrite, which are Fe atoms above the Ti atoms (Ti-termination) and Fe atoms above the C atoms (C-termination). Interfacial energy of the Ti-termination is larger than that of the C-termination, which means that for Fe atoms above the C atoms, the ability of TiC promotes ferrite heterogeneous nucleation on its surface is larger than that for Fe atoms above the Ti atoms

Microstructure and tribological properties of TiCu2Al intermetallic compound coating

International Nuclear Information System (INIS)

Guo Chun; Zhou Jiansong; Zhao Jierong; Wang Linqian; Yu Youjun; Chen Jianmin; Zhou Huidi

2011-01-01

TiCu 2 Al ternary intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding. Tribological properties of the prepared TiCu 2 Al intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiCu 2 Al intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiCu 2 Al intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate first increased and then decreased at normal load from 5 to 15 N.

APFIM and TEM investigations of precipitation in rapidly solidified 316 stainless steel

International Nuclear Information System (INIS)

Wisutmethangoon, S.; Kelly, T.F.; Flinn, J.E.; Camus, P.P.

1998-01-01

316 stainless steel has been rapid solidification-processed (RSP) by gas atomization and hot extrusion of the powder with the intent of improving the mechanical properties through fine-scale precipitation. Vanadium, nitrogen and oxygen have been introduced intentionally as alloying elements for this purpose. The yield strength after solution heat treatment of the RSP alloy is 450 MPa. By ageing at 600 C for 1000 h, the yield strength increases to 615 MPa with little loss of ductility (53% reduction of area). The ultimate tensile strength after cold work and ageing is 922 MPa. The morphology and composition of the precipitates in this steel have been investigated using APFIM and TEM techniques in order understand the origin of the high strength. A high numbered density (∼2 x 10 21 m -3 ) of 25 nm plate-like precipitates was observed with TEM in an aged specimen. The composition of these precipitates was analyzed using APFIM techniques, and was found to be a complex nitride of Cr, V, Fe, Ni and Mo. This nitride precipitate was not found in an unaged specimen of this alloy. These precipitates are responsible for improving mechanical properties by dispersion strengthening. (orig.)

Detection of free liquid in cement-solidified radioactive waste drums using computed tomography

International Nuclear Information System (INIS)

Steude, J.S.; Tonner, P.D.

1991-01-01

Acceptance criteria for disposal of radioactive waste drums require that the cement-solidified material in the drum contain minimal free liquid after the cement has hardened. Free liquid is to be avoided because it may corrode the drum, escape and cause environmental contamination. The DOE has requested that a nondestructive evaluation method be developed to detect free liquid in quantities in excess of 0.5% by volume. This corresponds to about 1 liter in a standard 208 liter (55 gallon) drum. In this study, the detection of volumes of free liquid in a 57 cm (2 ft.) diameter cement-solidified drum is demonstrated using high-energy X-ray computed tomography (CT0. In this paper it is shown that liquid concentrations of simulated radioactive waste inside glass tubes imbedded in cement can easily be detected, even for tubes with inner diameters less than 2 mm (0.08 in.). Furthermore, it is demonstrated that tubes containing water and liquid concentrations of simulated radioactive waste can be distinguished from tubes of the same size containing air. The CT images were obtained at a rate of about 6 minutes per slice on a commercially available CT system using a 9 MeV linear accelerator source

Fabrication of Ti-0.48Al Alloy by Centrifugal Casting.

Science.gov (United States)

Park, Jong Bum; Lee, Jung-Il; Ryu, Jeong Ho

2018-09-01

Many of the unique properties of TiAl alloys that make are attractive for use in high-temperature structural applications also make it challenging to process them into useful products. Cast TiAl is rapidly nearing commercialization, particularly in the vehicle industry, owing to its low production cost. In this study, the centrifugal casting of a TiAl (Ti-48%Al, mole fraction) turbocharger was simulated and an experimental casting was created in vacuum using an induction melting furnace coupled to a ceramic composite mold. Numerical simulation results agreed with the experiment. The crystal structure, microstructure, and chemical composition of the TiAl prepared by centrifugal casting were studied by X-ray diffractometry, optical microscopy, field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). FE-SEM and EDS examinations of the TiAl casting revealed that the thickness of the oxide layer (α-case) was typically less than 35 μm.

Setting of cesium residual ratio of molten solidified waste produced in Japan Atomic Power Company Tokai and Tokai No.2 Power Stations

International Nuclear Information System (INIS)

2013-02-01

JNES investigated the appropriateness of a view of the Japan Nuclear Fuel Co. on cesium residual content and the radioactivity measurement precision regarding the molten solidified (with lowered inorganic salt used) radioactive wastes which were produced from Japan Atomic Power Company Tokai and Tokai No. 2 Power Stations. Based on the written performance report from the request and past disposal confirmation experience, a view of the JNFC is confirmed as appropriate that setting of 15% cesium residual ratio for molten solidified with volume ratio larger than 4% and less than 10% cases. (S. Ohno)

Cold Heat Release Characteristics of Solidified Oil Droplet-Water Solution Latent Heat Emulsion by Air Bubbles

Science.gov (United States)

Inaba, Hideo; Morita, Shin-Ichi

The present work investigates the cold heat-release characteristics of the solidified oil droplets (tetradecane, C14H30, freezing point 278.9 K)/water solution emulsion as a latent heat-storage material having a low melting point. An air bubbles-emulsion direct-contact heat exchange method is selected for the cold heat-results from the solidified oil droplet-emulsion layer. This type of direct-contact method results in the high thermal efficiency. The diameter of air bubbles in the emulsion increases as compared with that in the pure water. The air bubbles blown from a nozzle show a strong mixing behavior during rising in the emulsion. The temperature effectiveness, the sensible heat release time and the latent heat release time have been measured as experimental parameters. The useful nondimensional emulsion level equations for these parameters have been derived in terms of the nondimensional emalsion level expressed the emulsion layer dimensions, Reynolds number for air flow, Stefan number and heat capacity ratio.

Importance of microscopy in durability studies of solidified and stabilized contaminated soils

Science.gov (United States)

Klich, I.; Wilding, L.P.; Drees, L.R.; Landa, E.R.

1999-01-01

Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or achieved in a laboratory warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical

Comparison of mechanical behavior of TiN, TiNC, CrN/TiNC, TiN/TiNC films on 9Cr18 steel by PVD

Science.gov (United States)

Feng, Xingguo; Zhang, Yanshuai; Hu, Hanjun; Zheng, Yugang; Zhang, Kaifeng; Zhou, Hui

2017-11-01

TiN, TiNC, CrN/TiNC and TiN/TiNC films were deposited on 9Cr18 steel using magnetron sputtering technique. The morphology, composition, chemical state and crystalline structure of the films were observed and analyzed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Hardness and adhesion force were tested by nanoindentation and scratch tester, respectively. The friction and wear behavior of TiN, TiNC, CrN/TiNC and TiN/TiNC films sliding against GCr15 balls were investigated and compared synthetically using ball-on-disk tribometer. It was found that Tisbnd N, Tisbnd C, Tisbnd Nsbnd C and Csbnd C bonds were formed. The TiN/TiNC film was composed of TiN, TiC and TiNC phases. Hardness and adhesion force results indicated that although the TiN film possessed the highest hardness, its adhesion force was lowest among all the films. Tribological test results showed that the friction coefficient of TiN/TiNC was much lower than that of TiN and the wear rate decreases remarkably from 2.3 × 10-15 m3/Nm to 7.1 × 10-16 m3/Nm, which indicated the TiN/TiNC film has better wear resistance.

Effect of solidification parameters on mechanical properties of directionally solidified Al-Rich Al-Cu alloys

Science.gov (United States)

Çadırlı, Emin

2013-05-01

Al(100-x)-Cux alloys (x=3 wt%, 6 wt%, 15 wt%, 24 wt% and 33 wt%) were prepared using metals of 99.99% high purity in vacuum atmosphere. These alloys were directionally solidified under steady-state conditions by using a Bridgman-type directional solidification furnace. Solidification parameters (G, V and ), microstructure parameters (λ1, λ2 and λE) and mechanical properties (HV, σ) of the Al-Cu alloys were measured. Microstructure parameters were expressed as functions of solidification parameters by using a linear regression analysis. The dependency of HV, σ on the cooling rate, microstructure parameters and composition were determined. According to experimental results, the microhardness and ultimate tensile strength of the solidified samples was increased by increasing the cooling rate and Cu content, but decreased with increasing microstructure parameters. The microscopic fracture surfaces of the different samples were observed using scanning electron microscopy. Fractographic analysis of the tensile fracture surfaces showed that the type of fracture significantly changed from ductile to brittle depending on the composition.

Performance demonstration program plan for RCRA constituent analysis of solidified wastes

International Nuclear Information System (INIS)

1995-06-01

Performance Demonstration Programs (PDPS) are designed to help ensure compliance with the Quality Assurance Objectives (QAOs) for the Waste Isolation Pilot Plant (WIPP). The PDPs are intended for use by the Department of Energy (DOE) Carlsbad Area Office (CAO) to assess and approve the laboratories and other measurement facilities supplying services for the characterization of WIPP TRU waste. The PDPs may also be used by CAO in qualifying laboratories proposing to supply additional analytical services that are required for other than waste characterization, such as WIPP site operations. The purpose of this PDP is to test laboratory performance for the analysis of solidified waste samples for TRU waste characterization. This performance will be demonstrated by the successful analysis of blind audit samples of simulated, solidified TRU waste according to the criteria established in this plan. Blind audit samples (hereinafter referred to as PDP samples) will be used as an independent means to assess laboratory performance regarding compliance with the QAOs. The concentration of analytes in the PDP samples will address levels of regulatory concern and will encompass the range of concentrations anticipated in actual waste characterization samples. Analyses that are required by the WIPP to demonstrate compliance with various regulatory requirements and which are included in the PDP must be performed by laboratories that demonstrate acceptable performance in the PDP. These analyses are referred to as WIPP analyses and the samples on which they are performed are referred to as WIPP samples for the balance of this document

Photodecomposition of volatile organic compounds using TiO2 nanoparticles.

Science.gov (United States)

Jwo, Ching-Song; Chang, Ho; Kao, Mu-Jnug; Lin, Chi-Hsiang

2007-06-01

This study examined the photodecomposition of volatile organic compounds (VOCs) using TiO2 catalyst fabricated by the Submerged Arc Nanoparticle Synthesis System (SANSS). TiO2 catalyst was employed to decompose volatile organic compounds and compare with Degussa-P25 TiO2 in terms of decomposition efficiency. In the electric discharge manufacturing process, a Ti bar, applied as the electrode, was melted and vaporized under high temperature. The vaporized Ti powders were then rapidly quenched under low-temperature and low-pressure conditions in deionized water, thus nucleating and forming nanocrystalline powders uniformly dispersed in the base solvent. The average diameter of the TiO2 nanoparticles was 20 nm. X-ray diffraction analysis confirmed that the nanoparticles in the deionized water were Anatase type TiO2. It was found that gaseous toluene exposed to UV irradiation produced intermediates that were even harder to decompose. After 60-min photocomposition, Degussa-P25 TiO2 reduced the concentration of gaseous toluene to 8.18% while the concentration after decomposition by SANSS TiO2 catalyst dropped to 0.35%. Under UV irradiation at 253.7 +/- 184.9 nm, TiO2 prepared by SANSS can produce strong chemical debonding energy, thus showing great efficiency, superior to that of Degussa-P25 TiO2, in decomposing gaseous toluene and its intermediates.

Evaluation of mechanical properties of nanocrystalline Ti-Mo-Fe-Sn alloys system; Avaliacao de propriedades mecanicas de ligas nanocristalinas do sistema Ti-Mo-Fe-Sn

Energy Technology Data Exchange (ETDEWEB)

Rocha, M.O.A; Vidilli, A.L.; Afonso, C.R.M., E-mail: andre.vidilli@gmail.com [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

2014-07-01

The Ti-6Al-4V, widely used in biomaterials, exhibits elastic modulus (E) of approximately 110GPa, which is significantly higher than the one of human bone (E = 10 to 30 GPa). In this project, a process of rapid solidification was utilized in 4 different alloys of Ti-Mo-Fe-Sn, in order to produce ultrafine nanocrystalline eutectic alloys, which present high strength (1800-2500 MPa), low elastic modulus (50-110 GPa) and good corrosion resistance. The alloys Ti{sub 62}Fe{sub 30}Mo{sub 8}, Ti{sub 56}Fe{sub 30}Mo{sub 8}Sn{sub 6}, Ti{sub 63}Fe{sub 23}Mo{sub 8}Sn{sub 6}, Ti{sub 60}Fe{sub 23}Mo{sub 8}Sn{sub 9} show Vickers microhardness de, respectively, 745 (1mm), 733 (1mm), 609 (1mm) e 651(1mm) HV. The characterization was performed using scanning electron microscopy (SEM) and X- ray diffraction (XRD). The results indicated the presence of a β-Ti (bcc) matrix and the intermetallic TiFe and Ti{sub 3}Sn phases, and the microstructure were formed by dendrites, and eutectic constituents, which were present in the compositions Ti{sub 62}Fe{sub 30}Mo{sub 8}, Ti{sub 56}Fe{sub 30}Mo{sub 8}Sn{sub 6}, Ti{sub 63}Fe{sub 23}Mo{sub 8}Sn{sub 6}, Ti{sub 60}Fe{sub 23}Mo{sub 8}Sn{sub 9}. (author)

Examination of solidified and stabilized matrices as a result of solidification and stabilization process of arseniccontaining sludge with portland cement and lime

Directory of Open Access Journals (Sweden)

Tanapon Phenrat

2004-02-01

Full Text Available By solidification and stabilization (S/S with Portland cement and lime, it is possible to reduce arsenic concentration in leachate of the arsenic-containing sludge from arsenic removal process by coagulation with ferric chloride. From the initial arsenic concentration in leachate of unsolidified /unstabilized sludge which was around 20.75 mg/L, the arsenic concentrations in leachate of solidified/stabilized waste were reduced to 0.3, 0.58, 1.09, and 1.85 mg/L for the waste-to-binder ratios of 0.15, 0.25, 0.5, and 1, respectively, due tothe formation of insoluble calcium-arsenic compounds. To be more cost effective for the future, alternative uses of these S/S products were also assessed by measurement of compressive strength of the mortar specimens. It was found that the compressive strengths of these matrices were from 28 ksc to 461 ksc. In conclusion, considering compressive strength and leachability of the solidified matrices, some of these solidified/ stabilized products have potential to serve as an interlocking concrete paving block.

Microstructural Characterization of Melt Extracted High-Nb-Containing TiAl-Based Fiber

Directory of Open Access Journals (Sweden)

Shuzhi Zhang

2017-02-01

Full Text Available The microstructure of melt extracted Ti-44Al-8Nb-0.2W-0.2B-1.5Si fiber were investigated. When the rotation speed increased from 2000 to 2600 r/min, the appearance of the wire was uniform with no Rayleigh-wave default. The structure was mainly composed of fine α2 (α phase dendritic crystal and a second phase between dendrite arms and grain boundaries. The precipitated second phases were confirmed to be Ti5Si3 from the eutectic reaction L→Ti5Si3 + α and TiB. As the lower content of Si and higher cooling rate, a divorced eutectic microstructure was obtained. Segregation of Ti, Nb, B, Si, and Al occurred during rapid solidification.

Solidified structure of Al-Pb-Cu alloys

International Nuclear Information System (INIS)

Ikeda, Tetsuyuki; Nishi, Seiki; Kumeuchi, Hiroyuki; Tatsuta, Yoshinori.

1986-01-01

Al-Pb-Cu alloys were cast into bars or plates in different two metal mold casting processes in order to suppress gravity segregation of Pb and to achieve homogeneous dispersion of Pb phase in the alloys. Solidified structures were analyzed by a video-pattern-analyzer. Plate castings 15 to 20 mm in thickness of Al-Pb-1 % Cu alloy containing Pb up to 5 % in which Pb phase particles up to 10 μm disperse are achieved through water cooled metal mold casting. The plates up to 5 mm in thickness containing Pb as much as 8 to 10 % cast in this process have dispersed Pb particles up to 5 μm in diameter in the surface layer. Al-8 % Pb-1 % Cu alloy bars 40 mm in diameter and 180 mm in height in which gravity segregation of Pb is prevented can be cast by movable and water sprayed metal mold casting at casting temperature 920 deg C and mold moving speed 1.0 mm/s. Pb phase particles 10 μm in mean size are dispersed in the bars. (author)

Microporous TiO2-WO3/TiO2 films with visible-light photocatalytic activity synthesized by micro arc oxidation and DC magnetron sputtering

International Nuclear Information System (INIS)

Wu, Kee-Rong; Hung, Chung-Hsuang; Yeh, Chung-Wei; Wu, Jiing-Kae

2012-01-01

Highlights: ► A simple MAO is used to prepare porous WO 3 /TiO 2 layer on Ti sheet as a visible-light enabled catalyst. ► The photocatalytic activity of the WO 3 /TiO 2 is enhanced by sputtering over an N,C-TiO 2 layer. ► This is ascribed to the synergetic effect of hybrid sample prepared by two-step method. - Abstract: This study reports the preparation of microporous TiO 2 -WO 3 /TiO 2 films with a high surface area using a two-step approach. A porous WO 3 /TiO 2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO 2 (N,C-TiO 2 ) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO 2 lattice using direct current magnetron sputtering. The resulting microporous TiO 2 -WO 3 /TiO 2 film with a 0.38-μm-thick N,C-TiO 2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO 2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO 2 -WO 3 /TiO 2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO 3 /TiO 2 can be used as a template of hybrid electrode because it enables rapid fabrication.

Location specific solidification microstructure control in electron beam melting of Ti-6Al-4V

Energy Technology Data Exchange (ETDEWEB)

Narra, Sneha P.; Cunningham, Ross; Beuth, Jack; Rollett, Anthony D.

2018-01-01

Relationships between prior beta grain size in solidified Ti-6Al-4V and melting process parameters in the Electron Beam Melting (EBM) process are investigated. Samples are built by varying a machine-dependent proprietary speed function to cover the process space. Optical microscopy is used to measure prior beta grain widths and assess the number of prior beta grains present in a melt pool in the raster region of the build. Despite the complicated evolution of beta grain sizes, the beta grain width scales with melt pool width. The resulting understanding of the relationship between primary machine variables and prior beta grain widths is a key step toward enabling the location specific control of as-built microstructure in the EBM process. Control of grain width in separate specimens and within a single specimen is demonstrated.

Microstructure and tribological properties of TiCu{sub 2}Al intermetallic compound coating

Energy Technology Data Exchange (ETDEWEB)

Guo Chun, E-mail: guochun@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Zhou Jiansong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhao Jierong; Wang Linqian; Yu Youjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Chen Jianmin; Zhou Huidi [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2011-04-15

TiCu{sub 2}Al ternary intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding. Tribological properties of the prepared TiCu{sub 2}Al intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiCu{sub 2}Al intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiCu{sub 2}Al intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate first increased and then decreased at normal load from 5 to 15 N.

Evaluation of physical stability and leachability of Portland Pozzolona Cement (PPC) solidified chemical sludge generated from textile wastewater treatment plants

International Nuclear Information System (INIS)

Patel, Hema; Pandey, Suneel

2012-01-01

Highlights: ► Stabilization/solidification of chemical sludge from textile wastewater treatment plants using Portland Pozzolona Cement (PPC) containing fly ash. ► Physical engineering (compressive strength and block density) indicates that sludge has potential to be reused for construction purpose after stabilization/solidification. ► Leaching of heavy metals from stabilized/solidified materials were within stipulated limits. ► There is a modification of microstructural properties of PPC with sludge addition as indicated by XRD and SEM patterns. - Abstract: The chemical sludge generated from the treatment of textile dyeing wastewater is a hazardous waste as per Indian Hazardous Waste Management rules. In this paper, stabilization/solidification of chemical sludge was carried out to explore its reuse potential in the construction materials. Portland Pozzolona Cement (PPC) was selected as the binder system which is commercially available cement with 10–25% fly ash interground in it. The stabilized/solidified blocks were evaluated in terms of unconfined compressive strength, block density and leaching of heavy metals. The compressive strength (3.62–33.62 MPa) and block density (1222.17–1688.72 kg/m 3 ) values as well as the negligible leaching of heavy metals from the stabilized/solidified blocks indicate that there is a potential of its use for structural and non-structural applications.

Kinetic analysis of the thermal decomposition of Li4Ti5O12 pellets

Directory of Open Access Journals (Sweden)

Hugo A. Mosqueda

2011-12-01

Full Text Available A single dynamic kinetic analysis, describing the surface decomposition of Li4Ti5O12 pellets, has been performed. Samples were analyzed by X-ray diffraction and scanning electron microscopy. The analyses were performed between 1000 and 1100°C and different times, perceiving the Li4Ti5O12 decomposition to Li2Ti3O7, with a loss of lithium. As expected, more rapid decomposition behaviour was found at higher temperatures. Finally, the activation energy for this decomposition of Li4Ti5O12 to Li2Ti3O7 was estimated to be equal to 383 kJ/mol.

Surface segregation of chromium in rapidly solidified Al studied by RBS and SPEM

International Nuclear Information System (INIS)

Tashlykova-Bushkevich, I.I.; Amati, M.; Aleman, B.; Gregoratti, L.; Kiskinova, M.; Ryabuhin, O.V.; Shepelevich, V.G.

2013-01-01

The present study demonstrates the advances of using scanning photoelectron microscopy and imaging accomplished by RBS and AFM to investigate the surface segregation of alloying elements in RS aluminum. Depth profiling of elemental composition indicates that RS microstructure evolution is influenced by solute-nanostructured defect interactions in Al-Cr alloys. It was found that Cr 2p and 3p core level photoemission spectra exhibits foil surface impoverishment of chromium. In agreement with dope depth profiling as carried out by RBS, the revealed phenomenon can be attributed to the fact that Cr drastically reduces the concentration of vacancies compared with RS pure Al, and affects H behaviour in RS Al-Cr alloys. Obtained results indicate that the surface microstructure of the Al alloy foils at the sub-micrometer scale, as far as the high density of quenched-in vacancies is concerned, is essential to elucidate how the microstructural morphology resulting from rapid solidification affects hydrogen trapping at lattice defects. (authors)

Oxidation Kinetics of Cast TiAl3

Science.gov (United States)

Smialek, J. L.; Humphrey, D. L.

1992-01-01

The isothermal oxidation kinetics of the TiAl3 compound over a wide temperature range is documented, and these rates are related to exclusive alpha-Al2O3 scale growth. The specific weight change vs time curves are shown. Two abnormalities are immediately apparent. One is that a rapid initial uptake of oxygen occurs at times less than 5 h, followed by a lower oxidation rate at longer times, for tests at 900 C and below. The other is that the final weight changes for the 700, 800, and 900 C tests are not in the sequence expected with respect to temperature. Isothermal oxidation of drop cast TiAl above 1000 C was found to exhibit parabolic oxidation controlled by protective alpha-Al2O3 scale formation. TiAl is the only phase in the binary Ti-Al system that forms exclusive scales of alpha-Al2O3 in isothermal oxidation. High anomalous rates at short times and at temperatures below 1000 C resulted from the internal oxidation of a second phase of aluminum.

Hot-working behavior of an advanced intermetallic multi-phase γ-TiAl based alloy

Energy Technology Data Exchange (ETDEWEB)

Schwaighofer, Emanuel, E-mail: emanuel.schwaighofer@unileoben.ac.at [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria); Clemens, Helmut [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria); Lindemann, Janny [Chair of Physical Metallurgy and Materials Technology, Brandenburg University of Technology, Konrad-Wachsmann-Allee 17, D-03046 Cottbus (Germany); GfE Fremat GmbH, Lessingstr. 41, D-09599 Freiberg (Germany); Stark, Andreas [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Mayer, Svea [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria)

2014-09-22

New high-performance engine concepts for aerospace and automotive application enforce the development of lightweight intermetallic γ-TiAl based alloys with increased high-temperature capability above 750 °C. Besides an increased creep resistance, the alloy system must exhibit sufficient hot-workability. However, the majority of current high-creep resistant γ-TiAl based alloys suffer from poor workability, whereby grain refinement and microstructure control during hot-working are key factors to ensure a final microstructure with sufficient ductility and tolerance against brittle failure below the brittle-to-ductile transition temperature. Therefore, a new and advanced β-solidifying γ-TiAl based alloy, a so-called TNM alloy with a composition of Ti–43Al–4Nb–1Mo–0.1B (at%) and minor additions of C and Si, is investigated by means of uniaxial compressive hot-deformation tests performed with a Gleeble 3500 simulator within a temperature range of 1150–1300 °C and a strain rate regime of 0.005–0.5 s{sup −1} up to a true deformation of 0.9. The occurring mechanisms during hot-working were decoded by ensuing constitutive modeling of the flow curves by a novel phase field region-specific surface fitting approach via a hyperbolic-sine law as well as by evaluation through processing maps combined with microstructural post-analysis to determine a safe hot-working window of the refined TNM alloy. Complementary, in situ high energy X-ray diffraction experiments in combination with an adapted quenching and deformation dilatometer were conducted for a deeper insight about the deformation behavior of the alloy, i.e. phase fractions and texture evolution as well as temperature uncertainties arising during isothermal and non-isothermal compression. It was found that the presence of β-phase and the contribution of particle stimulated nucleation of ζ-Ti{sub 5}Si{sub 3} silicides and h-type carbides Ti{sub 2}AlC enhance the dynamic recrystallization behavior during

Hot-working behavior of an advanced intermetallic multi-phase γ-TiAl based alloy

International Nuclear Information System (INIS)

Schwaighofer, Emanuel; Clemens, Helmut; Lindemann, Janny; Stark, Andreas; Mayer, Svea

2014-01-01

New high-performance engine concepts for aerospace and automotive application enforce the development of lightweight intermetallic γ-TiAl based alloys with increased high-temperature capability above 750 °C. Besides an increased creep resistance, the alloy system must exhibit sufficient hot-workability. However, the majority of current high-creep resistant γ-TiAl based alloys suffer from poor workability, whereby grain refinement and microstructure control during hot-working are key factors to ensure a final microstructure with sufficient ductility and tolerance against brittle failure below the brittle-to-ductile transition temperature. Therefore, a new and advanced β-solidifying γ-TiAl based alloy, a so-called TNM alloy with a composition of Ti–43Al–4Nb–1Mo–0.1B (at%) and minor additions of C and Si, is investigated by means of uniaxial compressive hot-deformation tests performed with a Gleeble 3500 simulator within a temperature range of 1150–1300 °C and a strain rate regime of 0.005–0.5 s −1 up to a true deformation of 0.9. The occurring mechanisms during hot-working were decoded by ensuing constitutive modeling of the flow curves by a novel phase field region-specific surface fitting approach via a hyperbolic-sine law as well as by evaluation through processing maps combined with microstructural post-analysis to determine a safe hot-working window of the refined TNM alloy. Complementary, in situ high energy X-ray diffraction experiments in combination with an adapted quenching and deformation dilatometer were conducted for a deeper insight about the deformation behavior of the alloy, i.e. phase fractions and texture evolution as well as temperature uncertainties arising during isothermal and non-isothermal compression. It was found that the presence of β-phase and the contribution of particle stimulated nucleation of ζ-Ti 5 Si 3 silicides and h-type carbides Ti 2 AlC enhance the dynamic recrystallization behavior during deformation within

Electrophoretic deposition of PEEK-TiO 2 composite coatings on stainless steel

KAUST Repository

Seuß, Sigrid

2012-03-01

Electrophoretic deposition (EPD) has been successfully used to deposit composite coatings composed of polyetheretherketone (PEEK) and titanium dioxide (TiO 2) nanoparticles on 316L stainless steel substrates. The suspensions of TiO2 nanoparticles and PEEK microparticles for EPD were prepared in ethanol. PEEK-TiO 2 composite coatings were optimized using suspensions containing 6wt% PEEK-TiO 2 in ethanol with a 3:1 ratio of PEEK to TiO 2 in weight and by applying a potential difference of 30 V for 1 minute. A heat-treatment process of the optimized PEEK-TiO 2 composite coatings was erformed at 335°C for 30 minutes with a heating rate of 10°Cmin -1 to densify the deposits. The EPD coatings were microstructurally evaluated by scanning electron microscopy (SEM). It was demonstrated that EPD is a convenient and rapid method to fabricate PEEK/TiO 2 coatings on stainless steel which are interesting for biomedical applications. © (2012) Trans Tech Publications, Switzerland.

Microstructure, Wear Resistance and Oxidation Behavior of Ni-Ti-Si Coatings Fabricated on Ti6Al4V by Laser Cladding.

Science.gov (United States)

Zhuang, Qiaoqiao; Zhang, Peilei; Li, Mingchuan; Yan, Hua; Yu, Zhishui; Lu, Qinghua

2017-10-30

The Ni-Ti-Si composite coatings were successfully fabricated on Ti6Al4V by laser cladding. The microstructure were studied by SEM (scanning electron microscopy) and EDS (energy dispersive spectrometer). It has been found that Ti₂Ni and Ti₅Si₃ phases exist in all coatings, and some samples have TiSi₂ phases. Moreover, due to the existence of these phases, coatings presented relatively higher microhardness than that of the substrate (826 HV (Vickers hardness)) and the microhardness value of coating 3 is about twice larger than that of the substrate. During the dry sliding friction and wear test, due to the distribution of the relatively ductile phase of Ti₂Ni and reinforcement phases of Ti₅Si₃ and TiSi₂, the coatings performed good wear resistance. The oxidation process contains two stages: the rapid oxidation and slow oxidation by high temperature oxidation test at 800 °C for 50 h. Meanwhile, the value of the oxidation weight gain of the substrate is approximately three times larger than that of the coating 4. During the oxidation process, the oxidation film formed on the coating is mainly consisted of TiO₂, Al₂O₃ and SiO₂. Phases Ti₂Ni, Ti₅Si₃, TiSi₂ and TiSi were still found and it could be responsible for the improvement in oxidation resistance of the coatings by laser cladding.

Heterogeneous nucleation of solid Al from the melt by TiB2 and Al3Ti: An ab initio molecular dynamics study

KAUST Repository

Wang, Junsheng; Horsfield, Andrew; Lee, Peter D.; Schwingenschlö gl, Udo

2010-01-01

The nucleation of solid Al from the melt by TiB2 is well established and is believed to involve the formation of Al3Ti. Since the atomic-scale mechanisms involved are not fully understood, we look to computer simulation to provide insight. As there is an absence of suitable potentials for all of this complex system we have performed large-scale density-functional-theory molecular dynamics simulations of the nucleation of solid Al from the melt on TiB2 and Al3Ti substrates at undercoolings of around 2 K. Using periodic boundary conditions, we find limited ordering and no signs of incipient growth in the liquid Al close to the B-terminated surface of TiB2. By contrast, we see fcc-like ordering near the Ti-terminated surface, with growth being frustrated by the lattice mismatch between bulk Al and the TiB2 substrate. The Al interatomic distances at the Ti-terminated surface are similar to distances found in Al3Ti; we suggest that the layer encasing TiB2 observed experimentally may be strained Al on a Ti-terminated surface rather than Al3Ti. For the Al3Ti substrate, fcc-like structures are observed on both sides which extend rapidly into the melt. Periodic boundaries introduce unphysical stresses which we removed by introducing a vacuum region to separate the liquid from the solid at one of the interfaces. We see ordering in the Al on both the B-terminated (0001) surface of TiB2, and on Al3Ti(112), with the ordering able to be stronger on the Al3Ti substrate. However, we cannot draw strong conclusions as these simulations need more time to allow long-ranged fluctuations in the liquid Al to dampen out. The huge computational cost restricted the range and duration of simulations that was possible.

Heterogeneous nucleation of solid Al from the melt by TiB2 and Al3Ti: An ab initio molecular dynamics study

KAUST Repository

Wang, Junsheng

2010-11-16

The nucleation of solid Al from the melt by TiB2 is well established and is believed to involve the formation of Al3Ti. Since the atomic-scale mechanisms involved are not fully understood, we look to computer simulation to provide insight. As there is an absence of suitable potentials for all of this complex system we have performed large-scale density-functional-theory molecular dynamics simulations of the nucleation of solid Al from the melt on TiB2 and Al3Ti substrates at undercoolings of around 2 K. Using periodic boundary conditions, we find limited ordering and no signs of incipient growth in the liquid Al close to the B-terminated surface of TiB2. By contrast, we see fcc-like ordering near the Ti-terminated surface, with growth being frustrated by the lattice mismatch between bulk Al and the TiB2 substrate. The Al interatomic distances at the Ti-terminated surface are similar to distances found in Al3Ti; we suggest that the layer encasing TiB2 observed experimentally may be strained Al on a Ti-terminated surface rather than Al3Ti. For the Al3Ti substrate, fcc-like structures are observed on both sides which extend rapidly into the melt. Periodic boundaries introduce unphysical stresses which we removed by introducing a vacuum region to separate the liquid from the solid at one of the interfaces. We see ordering in the Al on both the B-terminated (0001) surface of TiB2, and on Al3Ti(112), with the ordering able to be stronger on the Al3Ti substrate. However, we cannot draw strong conclusions as these simulations need more time to allow long-ranged fluctuations in the liquid Al to dampen out. The huge computational cost restricted the range and duration of simulations that was possible.

Microstructure and corrosion resistance of TC2 Ti alloy by laser cladding with Ti/TiC/TiB_2 powders

International Nuclear Information System (INIS)

Diao, Yunhua; Zhang, Kemin

2015-01-01

Highlights: • A TiC/TiB_2 composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB_2 powders. • A maximum hardness of 1100 HV was achieved in the laser clad TiC/TiB_2 composite layer. • Corrosion resistance of the TC2 alloy in NaCl (3.5 wt%) aqueous solution can be improved after laser cladding. - Abstract: In the present work, a TiC/TiB_2 composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB_2 powders. The surface microstructure, phase components and compositions were characterized with methods of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and energy dispersive spectrometry (EDS). The cladding layer is consisted of Ti, TiC and TiB_2. And the surface microhardness was measured. After laser cladding, a maximum hardness of 1100 HV is achieved in the laser cladding surface layer, which is more three times higher than that of the TC2 substrate (∼300 HV). Due to the formation of TiC and TiB_2 intermetallic compounds in the alloyed region and grain refinement, the microhardness of coating is higher than TC2 Ti alloy. In this paper, the corrosion property of matrix material and treated samples were both measured in NaCl (3.5 wt%) aqueous solution. From the result we can see that the laser cladding specimens’ corrosion property is clearly becoming better than that of the substrate.

Characteristics of laser clad α-Ti/TiC+(Ti,W)C1-x/Ti2SC+TiS composite coatings on TA2 titanium alloy

Science.gov (United States)

Zhai, Yong-Jie; Liu, Xiu-Bo; Qiao, Shi-Jie; Wang, Ming-Di; Lu, Xiao-Long; Wang, Yong-Guang; Chen, Yao; Ying, Li-Xia

2017-03-01

TiC reinforced Ti matrix composite coating with Ti2SC/TiS lubricant phases in-situ synthesized were prepared on TA2 titanium alloy by laser cladding with different powder mixtures: 40%Ti-19.5%TiC-40.5%WS2, 40%Ti-25.2%TiC-34.8%WS2, 40%Ti-29.4%TiC-30.6%WS2 (wt%). The phase compositions, microstructure, microhardness and tribological behaviors and wear mechanisms of coatings were investigated systematically. Results indicate that the main phase compositions of three coatings are all continuous matrix α-Ti, reinforced phases of (Ti,W)C1-x and TiC, lubricant phases of Ti2SC and TiS. The microhardness of the three different coatings are 927.1 HV0.5, 1007.5 HV0.5 and 1052.3 HV0.5, respectively. Compared with the TA2 titanium alloy (approximately 180 HV0.5), the microhardness of coatings have been improved dramatically. The coefficients of friction and the wear rates of those coatings are 0.41 and 30.98×10-5 mm3 N-1 m-1, 0.30 and 18.92×10-5 mm3 N-1 m-1, 0.34 and 15.98×10-5 mm3 N-1 m-1, respectively. Comparatively speaking, the coating fabricated with the powder mixtures of 40%Ti-25.2%TiC-34.8%WS2 presents superior friction reduction and anti-wear properties and the main wear mechanisms of that are slight plastic deformation and adhesive wear.

Formation and growth mechanism of TiC crystal in TiCp/Ti composites

Institute of Scientific and Technical Information of China (English)

金云学; 王宏伟; 曾松岩; 张二林

2002-01-01

Ti-C and Ti-Al-C alloys were prepared using gravity and directional solidification processes. Morphologies of TiC crystal were investigated by using SEM, XRD and EDX. Also, the formation and growth mechanism of TiC crystal have been analyzed on the basis of coordination polyhedron growth unit theory. During solidification of titanium alloys, the coordination polyhedron growth unit is TiC6. TiC6 growth units stack in a linking mode of edge to edge and form octahedral TiC crystal with {111} planes as present faces. Although the growing geometry of TiC crystal is decided by its lattice structure, the final morphology of TiC crystal depends on the effects of its growth environment. In solute concentration distribution, the super-saturation of C or TiC6 at the corners of octahedral TiC crystal is much higher than that of edges and faces of octahedral TiC crystal. At these corners the driving force for crystal growth is greater and the interface is instable which contribute to quick stacking rate of growth units at these corners and result in secondary dendrite arms along TiC crystallographic 〈100〉 directions. TiC crystal finally grows to be dendrites.

Preparation, characterization and applications of novel carbon and nitrogen codoped TiO2 nanoparticles from annealing TiN under CO atmosphere

International Nuclear Information System (INIS)

Sun, Mingxuan; Song, Peng; Li, Jing; Cui, Xiaoli

2013-01-01

CN-TiO 2 photoanodes in comparison with the commercial P25 (1.61%) and N-TiO 2 (2.44%) photoanodes. This work demonstrates that thermal treatment of TiN nanoparticles under CO atmosphere has shown to be a rapid, direct and clean approach to synthesize photocatalysts with enhanced photocatalytic and photovoltaic performance

Experimental Investigation of Closed Porosity of Inorganic Solidified Foam Designed to Prevent Coal Fires

Directory of Open Access Journals (Sweden)

Yi Lu

2015-01-01

Full Text Available In order to overcome the deficiency of the existing fire control technology and control coal spontaneous combustion by sealing air leakages in coal mines, inorganic solidified foam (ISF with high closed porosity was developed. The effect of sodium dodecyl sulfate (SDS concentration on the porosity of the foams was investigated. The results showed that the optimized closed porosity of the solidified foam was 38.65 wt.% for an SDS concentration of approximately 7.4×10-3 mol/L. Based on observations of the microstructure of the pore walls after solidification, it was inferred that an equilibrium between the hydration process and the drainage process existed. Therefore, the ISF was improved using three different systems. Gelatin can increase the viscosity of the continuous phase to form a viscoelastic film around the air cells, and the SDS + gelatin system can create a mixed surfactant layer at gas/liquid interfaces. The accelerator (AC accelerates the hydration process and coagulation of the pore walls before the end of drainage. The mixed SDS + gelatin + AC systems produced an ISF with a total porosity of 79.89% and a closed porosity of 66.89%, which verified the proposed stabilization mechanism.

Directionally solidified Al2O3/GAP eutectic ceramics by micro-pulling-down method

Science.gov (United States)

Cao, Xue; Su, Haijun; Guo, Fengwei; Tan, Xi; Cao, Lamei

2016-11-01

We reported a novel route to prepare directionally solidified (DS) Al2O3/GAP eutectic ceramics by micro-pulling-down (μ-PD) method. The eutectic crystallizations, microstructure characters and evolutions, and their mechanical properties were investigated in detail. The results showed that the Al2O3/GAP eutectic composites can be successfully fabricated through μ-PD method, possessed smooth surface, full density and large crystal size (the maximal size: φ90 mm × 20 mm). At the process of Diameter, the as-solidified Al2O3/GAP eutectic presented a combination of "Chinese script" and elongated colony microstructure with complex regular structure. Inside the colonies, the rod-type or lamellar-type eutectic microstructures with ultra-fine GAP surrounded by the Al2O3 matrix were observed. At an appropriate solidificational rate, the binary eutectic exhibited a typical DS irregular eutectic structure of "chinese script" consisting of interpenetrating network of α-Al2O3 and GAP phases without any other phases. Therefore, the interphase spacing was refined to 1-2 µm and the irregular microstructure led to an outstanding vickers hardness of 17.04 GPa and fracture toughness of 6.3 MPa × m1/2 at room temperature.

Study on the barrier performance of molten solidified waste (I). Review of the performance assessment research

Energy Technology Data Exchange (ETDEWEB)

Maeda, Toshikatsu; Sakamoto, Yoshiaki; Nakayama, Shinichi; Yamaguchi, Tetsuji; Ogawa, Hiromichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2001-02-01

Application of melting technique is thought as one of the effective methods to treatment of the waste from the view point of its homogeneity and waste volume reduction. Solidified products by melting are expected as potential candidates of engineered barrier in a repository due to the good properties for their stabilization of radionuclides and hazardous elements. However, the methodology of performance evaluation has not been estimated so far. In this report, a literature survey on the properties of molten solidified waste was performed. It is clarified that the leachability of waste elements such as Co or Sr in molten waste form would be controlled by the corrosion behaviors of iron or silica which are the matrix elements of the waste form. While, no investigations into the durability of waste form have performed so far. Also noticed that the research items on performance evaluation such as the leachability for long-lived radionuclides and durability of waste form would be necessary for the long-term barrier assessment on the disposal. (author)

The effect of grain size and cement content on index properties of weakly solidified artificial sandstones

Science.gov (United States)

Atapour, Hadi; Mortazavi, Ali

2018-04-01

The effects of textural characteristics, especially grain size, on index properties of weakly solidified artificial sandstones are studied. For this purpose, a relatively large number of laboratory tests were carried out on artificial sandstones that were produced in the laboratory. The prepared samples represent fifteen sandstone types consisting of five different median grain sizes and three different cement contents. Indices rock properties including effective porosity, bulk density, point load strength index, and Schmidt hammer values (SHVs) were determined. Experimental results showed that the grain size has significant effects on index properties of weakly solidified sandstones. The porosity of samples is inversely related to the grain size and decreases linearly as grain size increases. While a direct relationship was observed between grain size and dry bulk density, as bulk density increased with increasing median grain size. Furthermore, it was observed that the point load strength index and SHV of samples increased as a result of grain size increase. These observations are indirectly related to the porosity decrease as a function of median grain size.

In situ photodeposition of amorphous CoSx on the TiO2 towards hydrogen evolution

Science.gov (United States)

Chen, Feng; Luo, Wei; Mo, Yanping; Yu, Huogen; Cheng, Bei

2018-02-01

Cocatalyst modification of photocatalysts is an important strategy to enhance the photocatalytic performance by promoting effective separation of photoinduced electron-hole pairs and providing abundant active sites. In this study, a facile in situ photodeposition method was developed to prepare amorphous CoSx-modified TiO2 photocatalysts. It was found that amorphous CoSx nanoparticles were solidly loaded on the TiO2 surface, resulting in a greatly improved photocatalytic H2-evolution performance. When the amount of amorphous CoSx was 10 wt%, the hydrogen evolution rate of the CoSx/TiO2 reached 119.7 μmol h-1, which was almost 16.7 times that of the pure TiO2. According to the above experimental results, a reasonable mechanism of improved photocatalytic performance is proposed for the CoSx/TiO2 photocatalysts, namely, the photogenerated electrons of TiO2 can rapidly transfer to amorphous CoSx nanoparticles due to the solid contact between them, and then amorphous CoSx can provide plenty of sulfur active sites to rapidly adsorb protons from solution to produce hydrogen by the photogenerated electrons. Considering the facile synthesis method, the present cheap and highly efficient amorphous CoSx-modified TiO2 photocatalysts would have great potential for practical use in photocatalytic H2 production.

Tensile properties and microstructure of direct metal laser-sintered TI6AL4V (ELI alloy

Directory of Open Access Journals (Sweden)

Moletsane, M. G.

2016-11-01

Full Text Available Direct metal laser sintering (DMLS is an additive manufacturing technology used to melt metal powder by high laser power to produce customised parts, light-weight structures, or other complex objects. During DMLS, powder is melted and solidified track-by-track and layer-by-layer; thus, building direction can influence the mechanical properties of DMLS parts. The mechanical properties and microstructure of material produced by DMLS can depend on the powder properties, process parameters, scanning strategy, and building geometry. In this study, the microstructure, tensile properties, and porosity of DMLS Ti6Al4V (ELI horizontal samples were analysed. Defect analysis by CT scans in pre-strained samples was used to detect the crack formation mechanism during tensile testing of as-built and heat-treated samples. The mechanical properties of the samples before and after stress relieving are discussed.

Structural evolution of Ti/TiC multilayers

International Nuclear Information System (INIS)

Dahan, I.; Frage, N.; Dariel, M.P.

2004-01-01

Hard coatings based on metal/ceramic multilayers with periods in the nanometer range have been shown to possess some potential for improved tribological and mechanical properties. The present work is concerned with the structural evolution of (Ti/TiC) multilayers. Two kinds of multilayers consisting of 30 equithick (40 nm)TiC layers and 20 and 60 nm thick Ti layers, respectively, were sputter deposited on Mo substrates. The structural and the compositional evolution of these multilayers were examined by x-ray diffraction, transition electron microscopy (TEM), high-resolution TEM, Auger electron microscopy spectroscopy and differential thermal analysis (DTA), in the as-deposited state and after various heat treatments up to 500 deg. C. Initially, the Ti layers had a crystalline columnar grain structure displaying a (002) texture. The TiC layers displayed weak crystallinity with a pronounced (111) texture. In the course of the heat treatments, carbon diffused from the carbide layer into the adjacent Ti layers transforming the latter into off-stoichiometric TiC x with x≅0.5 and simultaneously depleting the carbon content of the initial carbide layer. The formed TiC x layers maintained the textural relationship with the neighboring TiC layers, consistent with a transformation that involved only a ABAB to ABC stacking change of the Ti sublattice. Increased mobility of the Ti atoms in carbon-depleted original TiC layers led to their full or partial recrystallization. The thermal effects associated both with the transformation of Ti layers into TiC, due to the influx of carbon atoms, and with the recrystallization of the original TiC layers were clearly revealed by the DTA measurements

Deposition and characterisation of multilayer hard coatings. Ti/TiNδ/TiCxNy/(TiC) a-C:H/(Ti) a-C:H

International Nuclear Information System (INIS)

Burinprakhon, T.

2001-02-01

Multilayer hard coatings containing Ti, TiNδ, TiC x N y , (TiC m ) a-C:H, (TiC n ) a-C:H, and (Ti) a-C:H were deposited on commercially pure titanium substrates by using an asymmetric bipolar pulsed-dc reactive magnetron sputtering of a titanium target, with Ar, Ar+N 2 , Ar+N 2 +CH 4 , and Ar+CH 4 gas mixtures. The microstructures, elemental compositions and bonding states of the interlayers and the coating surfaces were studied by using cross-sectional transmission electron microscopy (XTEM), electron energy loss spectroscopy (EELS), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The microstructure development of the multilayer coating was strongly influenced by target poisoning. As a result of the complete poisoning of the titanium target during the deposition of TiNδ and TiC x N y interlayers, the a-C:H interlayers containing graded titanium and nitrogen contents were found to develop successively to the TiC x N y interlayer without the formation of near-stoichiometric TiC. The (TiC m ) a-C:H interlayer consisted of nano-particles of distorted fcc crystal structure embedded in the a-C:H matrix. The (TiC n ) a-C:H and (Ti) a-C:H top layers were found to be a-C:H matrix without nano-particles. In the (Ti) a-C:H top layer there was no measurable amount of Ti observed, regardless of the variation of CH 4 concentration between 37.5 and 60 % flow rate in Ar+-CH4 gas mixture. The top layer (Ti) a-C:H was found to contain approximately 10 atomic % nitrogen, due to N 2 contamination during deposition caused by low conductance of N 2 through the nominally closed valve of the mass flow controller. The change of the CH 4 concentration during deposition of the top layer (Ti) a-C:H, however, showed a strong influence on the hydrogen content. The comparison of the fluorescence background of the Raman spectra revealed that hydrogen-less (Ti) a-C:H was deposited at a CH 4 concentration of less than 50 % flow rate in Ar. The hardness

Fabrication and characterization of laminated Ti-(TiB+La2O3/Ti composite

Directory of Open Access Journals (Sweden)

Yuanfei Han

2015-10-01

Full Text Available The incorporation of ceramic particulate reinforcements into titanium alloys can improve the specific strength and specific stiffness, while inevitably reduce the plasticity and ductility. In this study, in situ synthesized multilayer Ti-(TiB+La2O3/Ti composite was designed by learning from the microstructure of nature biological materials with excellent mechanical properties. The Ti-(TiB+La2O3/Ti composite with unique characteristic of laminated structure was prepared by combined powder metallurgy and hot rolling. The method has the synthesize advantages with in-situ reaction of Ti and LaB6 at high temperature and controllability of reinforcements size and constituent phases in composites. The result shows that the pores in the as sintered laminated structure composite completely disappeared after hot rolling at 1050 °C. The agglomerated reinforcement particles were well dispersed and distributed uniformly along the rolling direction. The thickness of pure Ti layer and (TiB+La2O3/Ti composite layer decreased from 1 mm to about 200 μm. Meanwhile, the grains size was refined obviously after rolling deformation. The room temperature tensile test indicates that the elongation of the laminated Ti-(TiB+La2O3/Ti composite improved from 13% to 17% in comparison with the uniform (TiB+La2O3/Ti composite, while the tensile strength had little change. It provides theoretical and experimental basis for fabricating the novel high performance laminated Ti-(TiB+La2O3/Ti composites.

In situ NiTi/Nb(Ti) composite

International Nuclear Information System (INIS)

Jiang, Daqiang; Cui, Lishan; Jiang, Jiang; Zheng, Yanjun

2013-01-01

Graphical abstract: - Highlights: • In situ NiTi/Nb(Ti) composites were fabricated. • The transformation temperature was affected by the mixing Ti:Ni atomic ratios. • The NiTi component became micron-scale lamella after forging and rolling. • The composite exhibited high strength and high damping capacity. - Abstract: This paper reports on the creation of a series of in situ NiTi/Nb(Ti) composites with controllable transformation temperatures based on the pseudo-binary hypereutectic transformation of NiTi–Nb system. The composite constituent morphology was controlled by forging and rolling. It is found that the thickness of the NiTi lamella in the composite reached micron level after the hot-forging and cold-rolling. The NiTi/Nb(Ti) composite exhibited high damping capacity as well as high yield strength

Effect of addition of tantalum and zirconium on the mechanical behavior of aluminum grain refined by Ti+ B

International Nuclear Information System (INIS)

Zaid, A.I.O.

2003-01-01

Aluminum and its alloys normally solidify in a columnar structure with coarse grains. Therefore, they are normally grain refined by adding either titanium or titanium + boron to their melts to obtain finer grain size and better surface quality. Other elements may be added beside the grain refiners to enhance their grain refinement efficiency and improve the mechanical behavior. Some elements were found to improve the grain refining efficiency of the master alloys e.g., vanadium, molybdenum, while others were found to deteriorate the grain refining efficiency e.g., zirconium and tantalum. The literature reveals that in general, only one element is added in the presence of the binary AI-Ti or the ternary AI-Ti-B grain refining master alloy. It is, therefore, anticipated that the addition of Ta and Zr may have different effect when added together from that if each element is added alone. This formed the main objective of this paper. In this paper, the effect of addition of either Zr, Ta or both of them together, with a percentage of 0.1 %wt each, on the grain size, hardness and mechanical behavior of AI and AI grain refined by Ti+B is investigated. It was found that adding Zr or Ta to commercially pure aluminum resulted in grain refinement of its structure and resulted in slight improvement of its hardness. However, a pronounced improvement was obtained in its mechanical strength and formability. On the other hand, addition of either Zr or Ta to Al grain refined by Ti+B resulted in poisoning effect i.e. reducing the grain refining efficiency of the AI- Ti-B master alloy. Practically, addition of either Zr or Ta has no effect on its hardness but resulted in a pronounced improvement of its mechanical strength. Finally, the addition of Zr + Ta to commercially pure aluminum or to aluminum grain refined by Ti+B resulted in reduction of grain size, little improvement in hardness and pronounced improvement in mechanical strength than when each element was added alone

Rapid synthesis of beta zeolites

Science.gov (United States)

Fan, Wei; Chang, Chun -Chih; Dornath, Paul; Wang, Zhuopeng

2015-08-18

The invention provides methods for rapidly synthesizing heteroatom containing zeolites including Sn-Beta, Si-Beta, Ti-Beta, Zr-Beta and Fe-Beta. The methods for synthesizing heteroatom zeolites include using well-crystalline zeolite crystals as seeds and using a fluoride-free, caustic medium in a seeded dry-gel conversion method. The Beta zeolite catalysts made by the methods of the invention catalyze both isomerization and dehydration reactions.

Surface free energy of polypropylene and polycarbonate solidifying at different solid surfaces

International Nuclear Information System (INIS)

Chibowski, Emil; Terpilowski, Konrad

2009-01-01

Advancing and receding contact angles of water, formamide, glycerol and diiodomethane were measured on polypropylene (PP) and polycarbonate (PC) sample surfaces which solidified at Teflon, glass or stainless steel as matrix surfaces. Then from the contact angle hystereses (CAH) the apparent free energies γ s tot of the surfaces were evaluated. The original PP surface is practically nonpolar, possessing small electron donor interaction (γ s - =1.91mJ/m 2 ), as determined from the advancing contact angles of these liquids. It may result from impurities of the polymerization process. However, it increases up to 8-10 mJ/m 2 for PP surfaces contacted with the solids. The PC surfaces both original and modified show practically the same γ s - =6.56.7mJ/m 2 . No electron acceptor interaction is found on the surfaces. The γ s tot of modified PP and PC surfaces depend on the kind of probe liquid and contacted solid surface. The modified PP γ s tot values determined from CAH of polar liquids are greater than that of original surface and they increase in the sequence: Teflon, glass, stainless steel surface, at which they solidified. No clear dependence is observed between γ s tot and dielectric constant or dipole moment of the polar probe liquids. The changes in γ s tot of the polymer surfaces are due to the polymer nature and changes in its surface structure caused by the structure and force field of the contacting solid. It has been confirmed by AFM images.

Microstructure and corrosion resistance of TC2 Ti alloy by laser cladding with Ti/TiC/TiB{sub 2} powders

Energy Technology Data Exchange (ETDEWEB)

Diao, Yunhua, E-mail: 990722012@qq.com; Zhang, Kemin, E-mail: zhangkm@sues.edu.cn

2015-10-15

Highlights: • A TiC/TiB{sub 2} composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB{sub 2} powders. • A maximum hardness of 1100 HV was achieved in the laser clad TiC/TiB{sub 2} composite layer. • Corrosion resistance of the TC2 alloy in NaCl (3.5 wt%) aqueous solution can be improved after laser cladding. - Abstract: In the present work, a TiC/TiB{sub 2} composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB{sub 2} powders. The surface microstructure, phase components and compositions were characterized with methods of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and energy dispersive spectrometry (EDS). The cladding layer is consisted of Ti, TiC and TiB{sub 2}. And the surface microhardness was measured. After laser cladding, a maximum hardness of 1100 HV is achieved in the laser cladding surface layer, which is more three times higher than that of the TC2 substrate (∼300 HV). Due to the formation of TiC and TiB{sub 2} intermetallic compounds in the alloyed region and grain refinement, the microhardness of coating is higher than TC2 Ti alloy. In this paper, the corrosion property of matrix material and treated samples were both measured in NaCl (3.5 wt%) aqueous solution. From the result we can see that the laser cladding specimens’ corrosion property is clearly becoming better than that of the substrate.

Effect of nano-CeO 2 on microstructure properties of TiC/TiN+TiCN ...

Indian Academy of Sciences (India)

TiC/TiN+TiCN-reinforced composite coatings were fabricated on Ti–6Al–4V alloy by laser cladding, which improved surface performance of the substrate. ... X-ray diffraction results indicated that Al3Ti+TiC/TiN+nano-CeO2 laser-cladded coating consisted of Ti3Al, TiC, TiN, Ti2Al20Ce, TiC0.3N0.7, Ce(CN)3 and CeO2, this ...

Oxidation behavior of TiC, ZrC, and HfC dispersed in oxide matrices

International Nuclear Information System (INIS)

Arun, R.; Subramanian, M.; Mehrotra, G.M.

1990-01-01

The oxidation behavior of hot pressed TiC-Al 2 O 3 , TiC-ZrO 2 , ZrC-ZrO 2 , and HfC-HfO 2 composites has been investigated at 1273 K. The oxidation of TiC, ZrC, and HfC in hot-pressed composites containing ZrO 2 and HfO 2 has been found to be extremely rapid. The kinetics of oxidation of TiC and a 90 wt% TiC-Al 2 O 3 composite appear to be faster compared to that of pure TiC. X-ray diffraction results for hot-pressed ZrC-HfO 2 and HfC-HfO 2 composites indicate partial stabilization of tetragonal ZrO 2 and HfO 2 phases in these composites

Effect of plasma molybdenized buffer layer on adhesive properties of TiN film coated on Ti6Al4V alloy

Energy Technology Data Exchange (ETDEWEB)

Qin, Lin, E-mail: qinlin@tyut.edu.cn; Yi, Hong; Kong, Fanyou; Ma, Hua; Guo, Lili; Tian, Linhai; Tang, Bin

2017-05-01

Highlights: • A molybdenized layer was prepared as a buffer layer under TiN film on Ti6Al4V. • The molybdenized layer can enhance adhesion strength of PVD coatings effectively. • The duplex treated samples increase elastic energy ratio in the impact tests. • The enhancement attributes to the hardness improvement and inverted-S shape elastic modulus profile of the modified layer. - Abstract: Effect of molybdenized buffer layer on adhesion strength of TiN film on Ti6Al4V alloy was investigated. The buffer layer composed of a dense molybdenum deposition layer, a rapid drop zone and a slow fall zone was prepared using double glow plasma surface alloying technique. Scratch tests and low energy repeated impact tests were adopted to comparatively evaluate the duplex treated layers and the single TiN samples. The results show that the critical load was increased from 62 N for the single TiN film to over 100 N for the duplex treated layer. The volume of impact pit, formed in impact tests, of the single TiN samples is 9.15 × 10{sup 6} μm{sup 3}, and about 1.5 times than that of the duplex treated samples. The Leeb hardness values reveal that about 70% impact energy was transferred to the single TiN samples to generate permanent deformation, while that was only about 47% for the duplex treated samples. The mechanism of improving adhesion strength is attributed to synergistic effect due to an inverted-S shape elastic modulus distribution produced by the molybdenized layer.

Investigation of Ti-Fe-Co bulk alloys with high strength and enhanced ductility

International Nuclear Information System (INIS)

Louzguine-Luzgin, Dmitri V.; Louzguina-Luzgina, Larissa V.; Kato, Hidemi; Inoue, Akihisa

2005-01-01

High-strength Ti-Fe-Co alloys were produced in the shape of arc-melted ingots with the dimensions of about 20-25mm in diameter and 7-10mm in height. The structure of the Ti-Fe-Co alloys (at Fe/Co ratio >1) studied by X-ray diffractometry and scanning electron microscopy consisted of an ordered Pm3-bar m Ti(FeCo) compound and a disordered body-centered cubic Im3-bar m β-Ti solid solution. The optimization of the Ti-Fe-Co alloy composition is performed from the viewpoint of both high strength and ductility. The strongest Ti-Fe-Co alloys have a hypereutectic structure and exhibit a high strength of about 2000MPa and a plastic deformation of 15%. The high strength and ductility values can be achieved without using the injection mould casting or rapid solidification procedure. The deformation behavior and the fractography of Ti-Fe-Co alloys are studied in detail

Magnetic anisotropy in rapidly quenched amorphous glass-coated nanowires

Energy Technology Data Exchange (ETDEWEB)

Óvári, T.-A.; Rotărescu, C.; Atițoaie, A.; Corodeanu, S.; Lupu, N., E-mail: nicole@phys-iasi.ro; Chiriac, H.

2016-07-15

Results on the roles played by the magnetoelastic and magnetostatic anisotropy terms in the magnetic behavior of glass-coated magnetostrictive amorphous nanowires prepared by means of rapid solidification are reported. Their contributions have been analyzed both experimentally, through hysteresis loop measurements, and theoretically, using micromagnetic simulations. All the investigated samples exhibit a magnetically bistable behavior, characterized by a single-step magnetization reversal when the applied field reaches a critical threshold value, called switching field. The combined interpretation of the experimental and theoretical data allows one to understand the effect of the magnetoelastic term on the value of the switching field, on one hand, and the effect of the magnetostatic term on the nucleation mechanism on the other, both with an essential impact on the characteristics of the nanowires’ magnetic bistability. The results are crucial for understanding the basic magnetic properties of these novel rapidly solidified ultrathin magnetic wires, as well as for tailoring their properties according to the specific requirements of various sensing applications. - Highlights: • Glass-coated nanowires have been very recently prepared by rapid solidification. • Amorphous wires change their properties as their diameter reaches the nano range. • Here we report on their main anisotropy terms: magnetoelastic and shape. • The results are essential for tailoring their properties for future applications.

Microstructure and mechanical properties of sintered Ti Binary alloys for dental applications

Energy Technology Data Exchange (ETDEWEB)

Yilmaz Atay, H.; Haro Rodriguez, M.; Amigo Mata, A.; Vicente Escuder, V.; Amigo Borras, V.

2016-07-01

Biomaterials have shown rapid growth in the field of elderly population demands with the prolongation of human life. One of those biomaterials, titanium, has excellent properties and biocompatibility though it may cause weakening in the structures due to its higher stiffness. In this study, powder metallurgy process was used to produce Ti-Cr, Ti-Mo and Ti-Cu metal alloys to overcome this problem. Metal powders were mixed by mechanical alloying. After pressing and sintering, alloys structures were investigated. Characterizations were carried out by size analyzer, SEM-EDX, optical microscope and three points bending test. (Author)

Microstructure Characteristic of In-situ Ti/TiC Composites

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

TiC reinforced titanium composites has been produced with different Al content and C content by XDTM. The results have shown that TiC particles are of two different morphologies: coarse dendritical primary TiC and short bar-shape eutectic TiC. Al content has great effects on the morphology of TiC. With the increasing of Al content, the morphology of primary TiC changes from coarse developed dendrite into short bar-shape or plate-shape TiC with 35%Al. Meanwhile, the structure of the matrix changes from single Ti to Ti and Ti3Al, and to Ti3Al and TiAl. However, the C content has no influence on the microstructure of matrix. When the C content is less than 1.2%, the dendrite TiC disappears and only short bar-shape or plate-shape TiC exists in the composites. In addition, the effect of heat treatment on the morphology of TiC has also studied.

Study on Magnesium in Rainwater and Fertilizer Infiltration to Solidified Peat

Science.gov (United States)

Tajuddin, S. A. M.; Rahman, J. A.; Mohamed, R. M. S. R.

2018-04-01

Magnesium is a component of several primary and secondary minerals in the soil which are essentially insoluble for agricultural purpose. The presence of water infiltrate in the soil allows magnesium to dissolve together into the groundwater. In fertilizers, magnesium is categorized as secondary macronutrient which supplies food and encouraging for plants growth. The main objective of this study was to determine the concentration of magnesium in fibric peat when applied the solidification under different conditions. Physical model was used as a mechanism for the analysis of the experimental data using a soil column as an equipment to produce water leaching. In this investigation, there were four outlets in the soil column which were prepared from the top of the column to the bottom with the purpose of identifying the concentration of magnesium for each soil level. The water leaching of each outlet was tested using atomic absorption spectroscopy (AAS). The results obtained showed that the highest concentrations of magnesium for flush and control condition at outlet 4 was 12.50 ppm and 1.29 ppm respectively. Similarly, fibric with solidified peat under rainwater recorded the highest value of 3.16 at outlet 1 for wet condition while for dry condition at outlet 4 of 1.33 ppm. However, the difference in fibric with solidified peat under rainwater and fertilizer condition showed that the highest value for the wet condition was achieved at outlet 1 with 5.43 ppm while highest value of 1.26 ppm was obtained for the dry condition at the outlet 4. It was concluded that the outlets in the soil column gave a detailed analysis of the concentration of magnesium in the soil which was influenced by the environmental conditions.

EPICOR-II: a field leaching test of solidified radioactively loaded ion exchange resin

International Nuclear Information System (INIS)

Davis, E.C.; Marshall, D.S.; Todd, R.A.; Craig, P.M.

1986-08-01

As part of an ongoing research program investigating the disposal of radioactive solid wastes in the environment' the Oak Ridge National Laboratory (ORNL) is participating with Argonne National Laboratory, the Idaho National Engineering Laboratory, and the Nuclear Regulatory Commission in a study of the leachability of solidified EPICOR-II ion-exchange resin under simulated disposal conditions. To simulate disposal, a group of five 2-m 3 soil lysimeters has been installed in Solid Waste Storage Area Six at ORNL, with each lysimeter containing a small sample of solidified resin at its center. Two solidification techniques are being investigated: a Portland cement and a vinyl ester-styrene treatment. During construction, soil moisture temperature cells were placed in each lysimeter, along with five porous ceramic tubes for sampling water near the waste source. A meteorological station was set up at the study site to monitor climatic conditions (primarily precipitation and air temperature), and a data acquisition system was installed to keep daily records of these meteorological parameters as well as lysimeter soil moisture and temperature conditions. This report documents the first year of the long-term field study and includes discussions of lysimeter installation, calibration of soil moisture probes, installation of the site meteorological station, and the results of the first-quarter sampling for radionuclides in lysimeter leachate. In addition, the data collection and processing system developed for this study is documented, and the results of the first three months of data collection are summarized in Appendix D

Microstructure characterization of laser-deposited titanium carbide and zirconium-based titanium metal matrix composites

CSIR Research Space (South Africa)

Ochonogor, OF

2012-09-01

Full Text Available . In this work, the technique is used to fabricate metal matrix composites (MMCs) by using an elementally blended feedstock combining metal and ceramic powders in the melt pool, which melt and solidify to create the required morphology. Ti6Al4V + TiC MMCs were...

Synthesis of Nano-Ilmenite (FeTiO3) doped TiO2/Ti Electrode for Photoelectrocatalytic System

Science.gov (United States)

Hikmawati; Watoni, A. H.; Wibowo, D.; Maulidiyah; Nurdin, M.

2017-11-01

Ilmenite (FeTiO3) doped on Ti and TiO2/Ti electrodes were successfully prepared by using the sol-gel method. The structure, morphology, and optical properties of FeTiO3 are characterized by XRD, UV-Vis DRS, and SEM. The FeTiO3 and TiO2 greatly affect the photoelectrocatalysis performance characterized by Linear Sweep Voltammetry (LSV) and Cyclic Voltammetry (CV). The characterization result shows a band gap of FeTiO3 is 2.94 eV. XRD data showed that FeTiO3 formed at 2θ were 35.1° (110), 49.9° (024), and 61.2° (214). The morphology of FeTiO3/Ti and FeTiO3.TiO2/Ti using SEM shows that the formation of FeTiO3 thin layer signifies the Liquid Phase Deposition method effectively in the coating process. Photoelectrochemical (PEC) test showed that FeTiO3.TiO2/Ti electrode was highly oxidation responsive under visible light compared to the FeTiO3/Ti electrodes i.e. 7.87×10-4 A and 9.87×10-5 A. Degradation test of FeTiO3/Ti and FeTiO3.TiO2/Ti electrodes on titan yellow showed that the percentages of degradation with photoelectrocatalysis at 0.5 mg/L were 41% and 43%, respectively.

Reactive synthesis of Ti-W-Cr-B mixing powder by spark plasma sintering; Hoden plasma shoketsu ni yoru Ti-W-Cr-B kongo funmatsu no hanno gosei

Energy Technology Data Exchange (ETDEWEB)

Kaga, H. [Hokkaido Industrial Technology Center, Sapporo (Japan); Carrillo-Heian, E.M.; Munir, Z.A. [University of California, CA, (United States)

2000-08-15

The reactive sintered compacts of Ti-W-Cr-B mixed powders were manufactured by a pulse electric current technique. Identification and characterization of the resulting boride phase were done using EPMA, XRD and other methods. The density of the sintered compacts rose rapidly with sintering temperature up to 1,773 K, at which temperature the relative density was 94%. Above this temperature, the density rose only slightly with increasing sintering temperature. The borides of Ti and W were synthesized from mixed metal powders by this method. The type of boride formed and its composition depended on sintering temperature. Compacts sintered at lower temperatures consisted of WB{sub 2} and TiB{sub 2} phases, but at the highest sintering temperature, 2,173K, the main phase was (Ti, W, Cr)B{sub 2} solid solution, in which W and Cr were dissolved in TiB{sub 2}. There was also a very small amount of {beta}-(W, Ti, Cr)B phase. By annealing compact sintered at high temperature, the (Ti, W, Cr)B{sub 2} solid solution phase decomposed and the amount decreased. (author)

Application of rapid solidification powder metallurgy to the fabrication of high-strength, high-ductility Mg-Al-Zn-Ca-La alloy through hot extrusion

Energy Technology Data Exchange (ETDEWEB)

Ayman, Elsayed, E-mail: ayman@jwri.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Junko, Umeda; Katsuyoshi, Kondoh [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

2011-01-15

The microstructure and mechanical properties of hot extruded Mg-7Al-1Zn-1Ca powder alloys with an addition of 1.5% La or 3.3% La were investigated. Both rapidly solidified powders, produced via spinning water atomization process, and cast billets were extruded at 573, 623 and 673 K to optimize the processing conditions for obtaining better mechanical response. Powders were consolidated using both cold compaction and spark plasma sintering. The tensile properties of the extruded alloys were then evaluated and correlated to their microstructures. The results showed that the use of rapidly solidified Mg-7Al-1Zn-1Ca alloy powders with La additions could lead to effective grain refinement and super saturation of alloying elements, which in turn resulted in the improved mechanical response. The Mg-7Al-1Zn-1Ca-1.5La alloy extruded at 573 K attained ultimate tensile strength of 450 {+-} xx MPa and elongation of 17 {+-} xx%, superior to the Mg-7Al-1Zn-1Ca-3.3La alloy and other Mg alloys like Mg-Al-Mn-Ca. This may help extend the application of Mg alloys to higher load-carrying parts while maintaining the excellent advantage of light weight.

Rapid Obtaining of Nano-Hydroxyapatite Bioactive Films on NiTi Shape Memory Alloy by Electrodeposition Process

Science.gov (United States)

Lobo, A. O.; Otubo, J.; Matsushima, J. T.; Corat, E. J.

2011-07-01

Nano-hydroxyapatite (n-HA) crystalline films have been developed in this study by electrodeposition method on NiTi shape memory alloy (SMA). The electrodeposition of the n-HA films was carried out using 0.042 mol/L Ca(NO3)2 · 4H2O + 0.025 mol/L (NH4) · 2HPO4 electrolytes by applying a constant potential of -2.0 V for 120 min and keeping the solution temperature at 70 °C. The characterization of n-HA films is of special importance since bioactive properties related to n-HA have been directly identified with its specific composition and crystalline structure. AFM, XRD, EDX, FEG-SEM and Raman spectroscopy shows a homogeneous film, with high crystallinity, special composition, and bioactivity properties (Ca/P = 1.93) of n-HA on NiTi SMA surfaces. The n-HA coating with special structure would benefit the use of NiTi alloy in orthopedic applications.

Thermal stability of Ti3SiC2 thin films

International Nuclear Information System (INIS)

Emmerlich, Jens; Music, Denis; Eklund, Per; Wilhelmsson, Ola; Jansson, Ulf; Schneider, Jochen M.; Hoegberg, Hans; Hultman, Lars

2007-01-01

The thermal stability of Ti 3 SiC 2 (0 0 0 1) thin films is studied by in situ X-ray diffraction analysis during vacuum furnace annealing in combination with X-ray photoelectron spectroscopy, transmission electron microscopy and scanning transmission electron microscopy with energy dispersive X-ray analysis. The films are found to be stable during annealing at temperatures up to ∼1000 deg. C for 25 h. Annealing at 1100-1200 deg. C results in the rapid decomposition of Ti 3 SiC 2 by Si out-diffusion along the basal planes via domain boundaries to the free surface with subsequent evaporation. As a consequence, the material shrinks by the relaxation of the Ti 3 C 2 slabs and, it is proposed, by an in-diffusion of O into the empty Si-mirror planes. The phase transformation process is followed by the detwinning of the as-relaxed Ti 3 C 2 slabs into (1 1 1)-oriented TiC 0.67 layers, which begin recrystallizing at 1300 deg. C. Ab initio calculations are provided supporting the presented decomposition mechanisms

Phototoxicity of TiO2 Nanoparticles to Two Aquatic Species: Daphnia magna and Zebrafish (Danio rerio) Embryo

Science.gov (United States)

Ecotoxicological studies on TiO2 nanoparticles (nano-TiO2) are expanding rapidly due to their widespread use in both industrial and consumer products. However, few studies have focused on their potential phototoxicity related to the photocatalytic property of the material. In thi...

Nial and Nial-Based Composites Directionally Solidified by a Containerless Zone Process. Ph.D. Thesis

Science.gov (United States)

Joslin, Steven M.

1995-01-01

A containerless electromagnetically levitated zone (CELZ) process has been used to directionally solidify NiAl and NiAl-based composites. The CELZ processing results in single crystal NiAl (HP-NiAl) having higher purity than commercially pure NiAl grown by a modified Bridgman process (CP-NiAl). The mechanical properties, specifically fracture toughness and creep strength, of the HP-NiAl are superior to binary CP-NiAl and are used as a base-line for comparison with the composite materials subsequently studied. Two-phase composite materials (NiAl-based eutectic alloys) show improvement in room temperature fracture toughness and 1200 to 1400 K creep strength over that of binary HP-NiAl. Metallic phase reinforcements produce the greatest improvement in fracture toughness, while intermetallic reinforcement produces the largest improvement in high temperature strength. Three-phase eutectic alloys and composite materials were identified and directionally solidified with the intent to combine the improvements observed in the two-phase alloys into one alloy. The room temperature fracture toughness and high temperature strength (in air) serve as the basis for comparison between all of the alloys. Finally, the composite materials are discussed in terms of dominant fracture mechanism observed by fractography.

Photoelectrochemical detection of the herbicide clethodim by using the modified metal-organic framework amino-MIL-125(Ti)/TiO2

International Nuclear Information System (INIS)

Jin, Dangqin; Yu, Liangyun; Xu, Qin; Hu, Xiaoya

2015-01-01

We describe a sensitive photoelectrochemical (PEC) sensor for the determination of the herbicide clethodim. The PEC sensor was constructed by using amino-MIL-125/TiO 2 (MIL stands for Materials from Institute Lavoisier), an amino-functionalized metal-organic framework (MOF) modified with TiO2. The amino-MIL-125/TiO 2 was synthesized by a simple one-step solvothermal method and placed on a glassy carbon electrode where it displays photoelectrocatalytic activity. Scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and X-ray diffractometry (XRD) were used to characterize the amino-MIL-125/TiO2. In the sensing process, amino-MIL-125/TiO 2 is illuminated by visible light to produce electrons. These excited electrons are delivered to the glassy carbon electrode, leaving positively charged holes (h+) on the surface of the amino-MIL-125/TiO 2 . The holes react with H 2 O to generate hydroxy radicals (•OH). Clethodim rapidly attacks the hydroxy radicals and improves the efficiency of charge separation, this leading to an enhanced photocurrent. Under the optimal experimental conditions, this photoelectrochemical method enables clethodim to be quantified in the concentration range from 0.2 to 25 μmol L −1 , with a detection limit (3 S/N) of 10 nmol L −1 . The assay was applied to the determination of clethodim in soil samples, and results were in acceptable agreement with data obtained by liquid chromatography/mass spectrometry. (author)

Electrosynthesis of Ti5Si3, Ti5Si3/TiC, and Ti5Si3/Ti3SiC2 from Ti-Bearing Blast Furnace Slag in Molten CaCl2

Science.gov (United States)

Li, Shangshu; Zou, Xingli; Zheng, Kai; Lu, Xionggang; Chen, Chaoyi; Li, Xin; Xu, Qian; Zhou, Zhongfu

2018-04-01

Ti5Si3, Ti5Si3/TiC, and Ti5Si3/Ti3SiC2 have been electrochemically synthesized from the Ti-bearing blast furnace slag/TiO2 and/or C mixture precursors at a cell voltage of 3.8 V and 1223 K to 1273 K (950 °C to 1000 °C) in molten CaCl2. The pressed porous mixture pellets were used as the cathode, and a solid oxide oxygen-ion-conducting membrane (SOM)-based anode was used as the anode. The phase composition and morphologies of the cathodic products were systematically characterized. The final products possess a porous nodular microstructure due to the interconnection of particles. The variations of impurity elements, i.e., Ca, Mg, and Al, have been analyzed, and the result shows that Ca and Mg can be almost completely removed; however, Al cannot be easily removed from the pellet due to the formation of Ti-Al alloys during the electroreduction process. The electroreduction process has also been investigated by the layer-depended phase composition analysis of the dipped/partially reduced pellets to understand the detailed reaction process. The results indicate that the electroreduction process of the Ti-bearing blast furnace slag/TiO2 and/or C mixture precursors can be typically divided into four periods, i.e., (i) the decomposition of initial Ca(Mg,Al)(Si,Al)2O6, (ii) the reduction of Ti/Si-containing intermediate phases, (iii) the removal of impurity elements, and (iv) the formation of Ti5Si3, TiC, and Ti3SiC2. It is suggested that the SOM-based anode process has great potential to be used for the direct and facile preparation of Ti alloys and composites from cheap Ti-containing ores.

Elevated temperature characterization of electron beam freeform fabricated Ti-6Al-4V and dispersion strengthened Ti-8Al-1Er

Energy Technology Data Exchange (ETDEWEB)

Bush, R.W., E-mail: ralph.bush@usafa.edu [Department of Engineering Mechanics, 2354 Fairchild Dr., U.S. Air Force Academy, USAF Academy, CO 80840 (United States); Brice, C.A. [Lockheed Martin Aeronautics Co., Fort Worth, TX (United States)

2012-09-30

Highlights: Black-Right-Pointing-Pointer Electron beam freeform fabrication process. Black-Right-Pointing-Pointer Ti-6Al-4V and rare-earth dispersion Ti alloy. Black-Right-Pointing-Pointer Tensile, creep, and oxidation properties comparable to alloys made with conventional fabrication methods. Black-Right-Pointing-Pointer Fabrication process allows use of rare-earth dispersion Ti alloy. - Abstract: Electron beam freeform fabrication is an additive manufacturing process that can be used to build fully dense, structural metallic parts directly from a three-dimensional computer model. This technique can replace conventional fabrication methods, such as forging or machining from plate, and enable significant cost, time, and tool savings. Additionally, this method enables the fabrication of alloys with novel compositions that are not well suited to production via ingot metallurgy processes. Ti-8Al-1Er is an experimental dispersion strengthened titanium alloy composition that requires rapid cooling to achieve optimal properties and thus is not amenable to ingot metallurgy production methods. Oxide dispersion strengthened alloys, such as Ti-8Al-1Er are known to have excellent thermal stability and improved high temperature properties. In this work, the room temperature tensile, elevated temperature tensile, creep properties and oxidation resistance of electron beam additive manufactured Ti-6Al-4V and Ti-8Al-1Er were measured and compared to those of laser beam additive manufactured Ti-8Al-1Er and wrought Ti-6Al-4V. Elevated temperature tensile properties were measured between 93 Degree-Sign and 538 Degree-Sign C. Creep tests were performed between 425 Degree-Sign and 455 Degree-Sign C at stresses between 345 and 483 MPa. It was found that the elevated temperature properties of the electron beam additive manufactured products are comparable to those of wrought forms. The elevated temperature strengths of Ti-8Al-1Er are comparable to those of Ti-6Al-4V in percentage of room

Microtexture formation of Ni99B1 alloys solidified on an ESL and an EML-a study based on the EBSP technique

International Nuclear Information System (INIS)

Li Mingjun; Ishikawa, Takehiko; Nagashio, Kosuke; Kuribayashi, Kazuhiko; Yoda, Shinichi

2007-01-01

We employed an electrostatic levitator (ESL) and an electromagnetic levitator (EML) to solidify Ni 99 B 1 (at.%) alloys at various undercoolings. The microstructures and microtextures were revealed by using the electron backscatter diffraction pattern (EBSP) technique in a scanning electron microscope. It is found that that no significant refinement can be identified at the low and medium undercooling regimes for the primary trunk in the sample solidified on the ESL, while the fragmentation of the secondary and even tertiary branches may take place to generate equiaxed grains. Further investigation by the EBSP reveals that neighboring grains have small misorientation angles, which may be ascribed to the absence of mechanical stirring from electromagnetic eddy current. A sharp contrast is that the samples solidified on the EML at low and medium undercoolings have refined equiaxed microstructures. The EBSP mapping reveals that the equiaxed grains yielded on the EML have a random distribution in crystallographic orientations among neighboring grains, indicating that electromagnetic stirring (EMS) induced by the electromagnetic field in the EML plays a vital role in promoting fragmentation and thus generating refined grains and random distribution in orientation. Regarding to the refined microstructure at high undercoolings, no significant difference arises in the samples processed between the EML and ESL

微量TiC对Mo-Ti-Zr-TiC合金性能与显微组织的影响%Effect of Trace TiC on Property and Microstructure of Mo-Ti-Zr-TiC Alloy

Institute of Scientific and Technical Information of China (English)

钱昭; 范景莲; 成会朝; 田家敏

2012-01-01

采用粉末冶金方法制备Mo-Ti-Zr-TiC合金,研究微量TiC的添加对Mo-Ti-Zr-TiC合金的拉伸性能和显微组织的影响.结果表明,在Mo-Ti-Zr合金中添加微量TiC(0.1％～0.5％,质量分数)后,合金的相对密度和室温抗拉强度得到了提高,当TiC添加量为0.4％时,合金强度最高,较Mo-Ti-Zr合金提高了28.1％.微量TiC的添加,阻碍了合金烧结过程中的晶粒长大,合金晶粒尺寸随TiC添加量的增加而降低.添加的细小TiC粒子在高温烧结过程中或与坯体中的微量氧发生反应形成了由Mo、Ti、C及O 4种元素组成的(Mo,Ti)xOyCz细小复合第二相粒子,或发生团聚结成大颗粒,对合金起到净化晶界氧和弥散强化的作用,因而合金的性能相比Mo-Ti-Zr合金有了较明显的提高.%Mo-Ti-Zr-TiC alloy was prepared via powder metallurgy method. The effects of trace TiC additive on the mechanical properties and microstructure of TiC reinforced Mo-Ti-Zr-TiC alloy were studied. The results indicate that the relative density and the tensile strength at room temperature of Mo-Ti-Zr-TiC alloy is effectively enhanced by adding trace TiC (0.1wt%~0.5wt%). The tensile strength achieves the highest value when the content of TiC is 0.4wt%, which is 28.1% higher than that of Mo-Ti-Zr alloy. The adding of trace TiC can inhibit the grain growth during alloy sintering process, which leads to the decrease of grain sizes with the rise of TiC content. A part of the fine TiC particles react with trace oxygen in molybdenum matrix to form (Mo,Ti)xOyC2 compound second phase particles during high temperature sintering, while the other part are agglomerated into large particles, which play a role in grain boundaries purification and dispersion-strengthening.

Order/disorder in electrodeposited aluminum-titanium alloys

Directory of Open Access Journals (Sweden)

Stafford G.R.

2003-01-01

Full Text Available The composition, morphology, and crystallographic microstructure of Al-Ti alloys electrodeposited from two different chloroaluminate molten salt electrolytes were examined. Alloys containing up to 28 % atomic fraction Ti were electrodeposited at 150 °C from 2:1 AlCl3-NaCl with controlled additions of Ti2+. The apparent limit on alloy composition is proposed to be due to a mechanism by which Al3Ti forms through the reductive decomposition of [Ti(AlCl43]-. The composition of Al-Ti alloys electrodeposited from the AlCl3-EtMeImCl melt at 80 °C is limited by the diffusion of Ti2+ to the electrode surface. Alloys containing up to 18.4 % atomic fraction Ti are only obtainable at high Ti2+ concentrations in the melt and low current densities. Alloys electrodeposited from the higher temperature melt have an ordered L12 crystal structure while alloys of similar composition but deposited at lower temperature are disordered fcc. The appearance of antiphase boundaries in the ordered alloys suggests that the deposit may be disordered initially and then orders in the solid state, subsequent to the charge transfer step and adatom incorporation into the lattice. This is very similar to the disorder-trapping observed in rapidly solidified alloys. The measured domain size is consistent with a mechanism of diffusion-controlled doman growth at the examined deposition temperatures and times.

Synthesis and microstructure characterization of Ni-Cr-Co-Ti-V-Al high entropy alloy coating on Ti-6Al-4V substrate by laser surface alloying

International Nuclear Information System (INIS)

Cai, Zhaobing; Jin, Guo; Cui, Xiufang; Liu, Zhe; Zheng, Wei; Li, Yang; Wang, Liquan

2016-01-01

Ni-Cr-Co-Ti-V-Al high-entropy alloy coating on Ti-6Al-4V was synthesized by laser surface alloying. The coating is composed of a B2 matrix and (Co, Ni)Ti 2 compounds with few β-Ti phases. Focused ion beam technique was utilized to prepare TEM sample and TEM observations agree well with XRD and SEM results. The formation of HEA phases is due to high temperature and rapid cooling rate during laser surface alloying. The thermodynamic parameters, ΔH mix , ΔS mix and δ as well as Δχ, should be used to predict the formation of the BCC solid solution, but they are not the strict criteria. Especially when Δχ reaches a high value (≥ 10%), BCC HEA will be partially decomposed, leading to the formation of (Co, Ni)Ti 2 compound phases. - Highlights: •Preparing HEA coating on Ti-6Al-4V by laser surface alloying is successful. •The synthesized HEA coating mainly consists of BCC HEA and (Co, Ni)Ti 2 compounds. •FIB technology was used to prepare the sample for TEM analysis. • ΔH mix , ΔS mix and δ as well as Δχ, should be all used to predict the formation of solid solution.

Experimental study on the properties of drum-packed, cement solidified waste package of pre and after sea dumping test of sea depth 30m and 100m

International Nuclear Information System (INIS)

Maki, Yasuro; Abe, Hirotoshi; Hattori, Seiichi

1976-01-01

Japan Marine Science and Technology Center has been tackling with the development of the monitoring system to confirm the soundness of drum-packed, cement-solidified low level radioactive waste (the package) during falling and after reaching at sea bed when it is dumped into sea. The test was carried out at Sagami Bay of 30 m and 100 m sea depth using non-radioactive packages. The observation of the falling behaviour of packages in sea was carried out by taking photographs of the motion of packages with an underwater 16 mm movie camera and an underwater industrial TV (ITV), and the observation of the soundness and the area of packages scattered on sea bed was carried out with an underwater ITV and an underwater 70 mm snap camera which were set up on the frame. The proportion of cement-solidified waste was decided so that the uni-axial compressive strength of the cement-solidified waste satisfies the condition of ''The tentative guideline''. Prior to tests at sea, hydrostatic pressure test of packages are carried out on land. After that, core specimens were sampled to obtain the uniaxial compressive strength from packages and were tested. After sea dumping tests, 6 packages were recovered from sea bed, and the soundness were tested. As the results, the deformation and damage of drums and cement solidified waste packages did not occur at all. (Kako, I.)

The effects of boron in TiAl/Ti3Al

International Nuclear Information System (INIS)

Feng, C.R.; Michel, D.J.; Crowe, C.R.

1989-01-01

The authors discuss the TiAl/Ti 3 Al interfacial misfit dislocations structures investigated by TEM in Ti-45Al alloy and Ti-45Al/TiB 2 composite. For TiAl with c/a = 1.02, only a single set of misfit dislocation arrays are crystallographically possible; these were observed in Ti-45Al alloy. However, the observation of three sets of misfit dislocation arrays in the Ti-45Al/TiB 2 composite suggests that the occupation of octahedral sites in the TiAl structure by excess boron was responsible for a decrease in the c/a ratio leading to an increased fcc character of the TiAl at the TiAl/Ti 3 Al interface

Preparation of TiO2-based nanotubes/nanoparticles composite thin film electrodes for their electron transport properties

International Nuclear Information System (INIS)

Zhao, Wanyu; Fu, Wuyou; Chen, Jingkuo; Li, Huayang; Bala, Hari; Wang, Xiaodong; Sun, Guang; Cao, Jianliang; Zhang, Zhanying

2015-01-01

The composite thin film electrodes were prepared with one-dimensional (1D) TiO 2 -B nanotubes (NTs) and zero-dimensional TiO 2 nanoparticles (NPs) based on different weight ratios. The electron transport properties of the NTs/NPs composite thin film electrodes applied for dye-sensitized solar cells had been investigated systematically. The results indicated that although the amount of dye adsorption decreased slightly, the devices with the NTs/NPs composite thin film electrodes could obtain higher open-circuit voltage and overall conversion efficiency compared to devices with pure TiO 2 NPs electrodes by rational tuning the weight ratio of TiO 2 -B NTs and TiO 2 NPs. When the weight ratio of TiO 2 -B NTs in the NTs/NPs composite thin film electrodes increased, the density of states and recombination rate decreased. The 1D structure of TiO 2 -B NTs can provide direct paths for electron transport, resulting in higher electron lifetime, electron diffusion coefficient and electron diffusion length. The composite thin film electrodes possess the merits of the rapid electron transport of TiO 2 -B NTs and the high surface area of TiO 2 NPs, which has great applied potential in the field of photovoltaic devices. - Highlights: • The composite thin film electrodes (CTFEs) were prepared with nanotubes and nanoparticles. • The CTFEs possess the rapid electron transport and high surface area. • The CTFEs exhibit lower recombination rate and longer electron life time. • The CTFEs have great applied potential in the field of photovoltaic devices

H_2O_2-assisted photocatalysis on flower-like rutile TiO_2 nanostructures: Rapid dye degradation and inactivation of bacteria

International Nuclear Information System (INIS)

Kőrösi, László; Prato, Mirko; Scarpellini, Alice; Kovács, János; Dömötör, Dóra; Kovács, Tamás; Papp, Szilvia

2016-01-01

Graphical abstract: - Highlights: • Hierarchically assembled rutile TiO_2 was synthesized at room temperature. • Hydrothermal treatment enhanced the crystallinity, while morphology was maintained. • Hydrothermal treatment also led to larger crystallites and a lower surface area. • Effective K. pneumoniae killing and MO degradation were achieved with the use of H_2O_2. • Higher crystallinity enhanced the reaction rate in the presence of H_2O_2. - Abstract: Hierarchically assembled flower-like rutile TiO_2 (FLH-R-TiO_2) nanostructures were successfully synthesized from TiCl_4 at room temperature without the use of surfactants or templates. An initial sol–gel synthesis at room temperature allowed long-term hydrolysis and condensation of the precursors. The resulting FLH-R-TiO_2 possessed relatively high crystallinity (85 wt%) and consisted of rod-shaped subunits assembling into cauliflower-like nanostructures. Hydrothermal evolution of FLH-R-TiO_2 at different temperatures (150, 200 and 250 °C) was followed by means of X-ray diffraction, transmission and scanning electron microscopy. These FLH-R-TiO_2 nanostructures were tested as photocatalysts under simulated daylight (full-spectrum lighting) in the degradation of methyl orange and in the inactivation of a multiresistant bacterium, Klebsiella pneumoniae. The effects of hydrothermal treatment on the structure, photocatalytic behavior and antibacterial activity of FLH-R-TiO_2 are discussed.

Highly efficient dual cocatalyst-modified TiO2 photocatalyst: RGO as electron-transfer mediator and MoSx as H2-evolution active site

Science.gov (United States)

Xu, Ying; Li, Yongan; Wang, Ping; Wang, Xuefei; Yu, Huogen

2018-02-01

The rapid interfacial charge transfer and interfacial catalytic reaction are highly desirable to improve the photocatalytic H2-evolution performance of semiconductor photocatalysts. To achieve the goal, in the paper, MoSx-rGO/TiO2 was synthesized by a facilely two-step photocatalytic reduction approach including reducing GO/TiO2 to rGO/TiO2 and then reducing ammonium tetrathiomolybdate ((NH4)2MoS4) to form amorphous MoSx on the rGO surface. In the case, the rGO nanosheets as an electron mediator caused rapid transportation of photogenerated electrons from the conduction band (CB) of TiO2, while amorphous MoSx served as an effective active site for the following interfacial reduction reaction for H2 evolution. The photocatalytic results indicated that the H2-evolution rate of synthesized MoSx-rGO/TiO2 was 206.6 μmol h-1, which was obviously higher than that of TiO2 (6.9 μmol h-1), rGO/TiO2 (31.8 μmol h-1) and MoSx/TiO2 (150.1 μmol h-1) due to the rapid interfacial charge transfer and interfacial catalytic reaction. Considering the present mild and green approach, the obtained MoSx-rGO/TiO2 could be regarded as a potential photocatalyst for the practical application. In addition, this work also could provide some new insights for the smart design and preparation of inexpensive and high-efficiency photocatalytic materials.

Site suitability criteria for solidified high level waste repositories

International Nuclear Information System (INIS)

Heckman, R.A.; Holdsworth, T.; Isherwood, D.; Towse, D.F.; Dayem, N.L.

1979-01-01

The NRC is developing a framework of regulations, criteria, and standards. Lawrence Livermore Laboratory provides broad technical support to the NRC for developing this regulatory framework, part of which involves site suitability criteria for solidified high-level wastes (SHLW). Both the regulatory framework and the technical base on which it rests have evolved in time. This document is the second report of the technical support project. It was issued as a draft working paper for a programmatic review held at LLL from August 16 to 18, 1977. It was printed and distributed solely as a briefing document on preliminary methodology and initial findings for the purpose of critical review by those in attendance. These briefing documents are being reprinted now in their original formats as UCID-series reports for the sake of the historical record. Analysis results have evolved as both the models and data base have changed. As a result, the methodology, models, and data base in this document are severely outmoded

Liquid phase interaction in TiC0,5N0,5-TiNi-Mo and TiC0,5N0,5-TiNi-Ti-Mo

International Nuclear Information System (INIS)

Askarova, L.Kh; Grigorov, I.G.; Zajnulin, Yu.G.

1998-01-01

Using the methods of X ray diffraction analysis, electron microscopy and X ray spectrum microanalysis a study was made into specific features of phase and structure formation in alloys TiC 0,5 N 0,5 -TiNi-Mo and TiC 0,5 N 0,5 -TiNi-Mo in the presence of a liquid phase at temperatures of 1380-1600 deg C. It is revealed that the physical and chemical processes taking place during the liquid-phase sintering result in the formation of a three-phase alloy consisting of nonstoichiometric titanium carbonitride TiC 0.5-x N 0.5-x , a molybdenum base solid solution of titanium, nickel and carbon Mo(Ti, Ni, C) and one of two intermetallic compounds, either TiNi or Ni 3 Ti. Metallic element concentration in individual phase constituents of the alloy is determined by means of X ray spectrum microanalysis

Synthesis of magnetic graphene oxide–TiO2 and their antibacterial properties under solar irradiation

International Nuclear Information System (INIS)

Chang, Ying-Na; Ou, Xiao-Ming; Zeng, Guang-Ming; Gong, Ji-Lai; Deng, Can-Hui; Jiang, Yan; Liang, Jie; Yuan, Gang-Qiang; Liu, Hong-Yu; He, Xun

2015-01-01

Highlights: • Magnetic graphene oxide–TiO 2 (MGO–TiO 2 ) composites were synthesized. • MGO–TiO 2 had excellent antibacterial activity toward Escherichia coli. • MGO–TiO 2 could effectively and rapidly separate from aqueous solution. • Carbonates and phosphates significantly reduced the bacterial survival rate. - Abstract: Titanium dioxide (TiO 2 ) has been intensively researched and increasingly used as antibacterial agent, but it suffers from separation inconvenience. Its effective removal from water after reaction while maintaining its high antibacterial activity becomes necessary. In this work, it was the first time the magnetic graphene oxide–TiO 2 (MGO–TiO 2 ) composites were prepared through a simple synthesis method. The results indicated that MGO–TiO 2 exhibited a good antibacterial activity against Escherichia coli. MGO–TiO 2 was found to almost completely inactivate the E. coli within 30 min under solar irradiation. The effect of inorganic ions present in E. coli suspension was also evaluated. Compared with other ions, HCO 3 − and HPO 4 2− had a greater influence on the antibacterial property

Retrievable surface storage: interim storage of solidified high-level waste

International Nuclear Information System (INIS)

LaRiviere, J.R.; Nelson, D.C.

1976-01-01

Studies have been conducted on retrievable-surface-storage concepts for the interim storage of solidified high-level wastes. These studies have been reviewed by the Panel on Engineered Storage, convened by the Committee on Radioactive Waste Management of the National Research Council-National Academy of Sciences. The Panel has concluded that ''retrievable surface storage is an acceptable interim stage in a comprehensive system for managing high-level radioactive wastes.'' The scaled storage cask concept, which was recommended by the Panel on Engineered Storage, consists of placing a canister of waste inside a carbon-steel cask, which in turn is placed inside a thick concrete cylinder. The waste is cooled by natural convection air flow through an annulus between the cask and the inner wall of the concrete cylinder. The complete assembly is placed above ground in an outdoor storage area

Microstructure and property of directionally solidified Ni-Si hypereutectic alloy

Science.gov (United States)

Cui, Chunjuan; Tian, Lulu; Zhang, Jun; Yu, Shengnan; Liu, Lin; Fu, Hengzhi

2016-03-01

This paper investigates the influence of the solidification rate on the microstructure, solid/liquid interface, and micro-hardness of the directionally solidified Ni-Si hypereutectic alloy. Microstructure of the Ni-Si hypereutectic alloy is refined with the increase of the solidification rate. The Ni-Si hypereutectic composite is mainly composed of α-Ni matrix, Ni-Ni3Si eutectic phase, and metastable Ni31Si12 phase. The solid/liquid interface always keeps planar interface no matter how high the solidification rate is increased. This is proved by the calculation in terms of M-S interface stability criterion. Moreover, the Ni-Si hypereutectic composites present higher micro-hardness as compared with that of the pure Ni3Si compound. This is caused by the formation of the metastable Ni31Si12 phase and NiSi phase during the directional solidification process.

Microstructures and phase relationships in the Ti3Al + Nb system

International Nuclear Information System (INIS)

Kestner-Weykamp, H.T.; Kaufman, M.J.

1989-01-01

Alloys based on the α 2 -Ti 3 Al compound (hexagonal) DO 19 are currently experiencing limited use as advanced aerospace materials. To date, the alloys with the most desirable properties contain additions of β stabilizers, such as Nb, Mo and V, which promote the formation of a two-phase mixture of α 2 +β or α 2 +B2 (where B2 refers to the ordered CsCl structure). Unfortunately, the phase relationships in these systems have not been established in sufficient detail to allow their more widespread application. Recently, there has been a series of investigations aimed at alleviating this deficiency in the ternary Ti-Al-Nb system. These studies have clearly indicated the existence of the ordered B2 phase, which, in the higher Nb alloys, can be retained at room temperature by rapid cooling from the liquid or solid state. The authors describe (TiNb) 3 Al alloys (from 0 to 30 at. pct. Nb) were studies after conventional and nonequilibrium (i.e., rapid solidification) processing with an emphasis on providing further insight into the transformation sequences and phase equilibria in these alloys

Isothermal section of the Ti-Si-B system at 1250 ° C in the Ti-TiSi2-TiB2 region

OpenAIRE

Ramos, Alfeu Saraiva; Baldan, Renato; Nunes, Carlos Angelo; Coelho, Gilberto Carvalho; Suzuki, Paulo Atsushi; Rodrigues, Geovani

2013-01-01

A partial isothermal section (Ti-TiSi2-TiB2 region) of the ternary Ti-Si-B system at 1250 ° C was determined from heat-treated alloys prepared via arc melting. Microstructural characterization has been carried out through scanning electron microscopy (SEM), x-ray diffraction (xRD) and wavelength dispersive spectrometry (WDS). The results have shown the stability of the near stoichiometric Ti6Si2B phase and a negligible solubility of boron in the Ti-silicides as well as of Si in the Ti-borides...

Effects of cation contaminants in conductive TiO2 ceramics

Science.gov (United States)

Yan, M. F.; Rhodes, W. W.

1982-12-01

Ten cation contaminants, namely Al, Ga, Co, Fe, Mg, Zn, Zr, Ca, Sr, and Ba were investigated for their effects on the electrical properties, microstructures, and discoloration of conductive TiO2 ceramics. It was found that Al, Ga, Co, Fe, and Mg cause discoloration and increase the electrical resistivity by a factor of 104 to 106 in Nb-doped TiO2 ceramics. The other dopants do not introduce such changes in TiO2. The electrical properties, microstructures, and discoloration were measured in specimens of AlxNb0.007Ti0.993-xO2 with 0≤x≤0.01. When the Al content exceeds a critical value, ranging from 0.48% at 1400 °C to 0.25% at 1200 °C, the electrical resistivities and grain size increase rapidly, and the specimen is discolored from the original black to an ivory white color. Color boundary migration induced by Al diffusion in Nb-doped TiO2 was quantitatively measured. From the kinetics of the boundary migration, the Al diffusivity (D) was calculated to be D=2.67 exp(-53.3 kcal/mole/RT) cm2/s in the temperature range of 1200 to 1400 °C. The rapid diffusion of the small cations, namely Al, Ga, Co, Fe, and Mg, results from an interstitial diffusion mechanism. However, other cations, having a radius larger than the interstitial channel (˜0.77 Å radius), cannot diffuse by this mechanism. Defect reactions are proposed to explain the increase in the electrical resistivity and microstructural changes due to Al diffusion. These defect reactions also show that the problem of acceptor contamination cannot be avoided by adding an excess quantity of donor dopant if the solubility of the donor is much less than that of the acceptor contaminant.

Combustion synthesis of TiC-based materials: Mechanisms, densification, and properties

International Nuclear Information System (INIS)

LaSalvia, J.C.; Meyers, M.A.

1995-01-01

The micromechanisms involved in the combustion synthesis of a Ti-C-Ni-Mo mixture resulting in the formation of a TiC-based composite were examined using the combustion wave quenching technique developed by Rogachev et al. At the micron level, the main reaction occurs at the interface between a Ti-Ni-C melt and C particles, resulting in the formation of a solid TiC x layer on the C particles. This layer undergoes a successive process of rapid growth and decomposition into TiC x spherules until all of the C particle is consumed. This mechanism is consistent with the apparent activation energy (E = 100 kJ/mol) for the process obtained from a macrokinetic investigation of the system. The apparent uniformity in size (d = 1 μm) of the TiC x spherules upon formation indicates a critical condition in the stability of the energetics involved in the process. These TiC x spherules undergo growth due to Ostwald ripening and coalescence mechanisms resulting in a final apparent size of 2.5 μm. For the compositions investigated, the addition of Mo did not affect either the micromechanisms or macrokinetics of the combustion synthesis process. Densification of the porous body after the combustion synthesis process can be carried out while it is still in a easily deformable state. The highly porous body is densified by a combination of fracture (communition), plastic deformation, and sintering. The mechanisms are identified for the case of combustion synthesized TiC. Mechanical properties and microstructures of a number of materials (e.g. TiC, TiB 2 , Al 2 O 3 -TiB 2 , TiB 2 -SiC, TiC-Ni-Mo) produced by combustion synthesis combined with a high-velocity forging step are reviewed

Photoemission study of the development of the Ti/GaAs(110) interface

International Nuclear Information System (INIS)

Ruckman, M.W.; del Giudice, M.; Joyce, J.J.; Weaver, J.H.

1986-01-01

Photoemission spectra of the Ga and As 3d core levels, the Ti 3p core levels, and the valence bands have been used to study the formation of the Ti/GaAs(110) interface. These results indicate that a multicomponent interfacial zone forms with reaction initiated at ultralow coverage and a rapid shift of E/sub F/ as the Schottky barrier forms (core-level shift 625 meV). After the onset of reaction, the Ga 3d core level shifts continuously to lower binding energy with increasing coverage (total shift of 1.66 eV by roughly-equal60 A Ti deposition). The As core-level profile indicates immediate reaction, the formation of two Ti: As bonding configurations at low coverage, and the appearance of another which persists to very high Ti coverage (> or =160 A) and is characteristic of a Ti-metal-rich environment. Core-level intensity profiles show preferential out-diffusion of As at every stage of interface formation. Core studies of the evolving Ti 3p emission show gradual convergence to bulk Ti as the overlayer becomes increasingly Ti rich. Likewise, valence-band studies reveal predominantly As-derived states below metal d states at E/sub F/. Comparison to previous results for Cr, V, Ce, and Sm overlayers on GaAs shows parallel trends in interface formation with differences related to the metal overlayer

A Laboratory Screening Study On The Use Of Solidifiers As A Response Tool To Remove Crude Oil Slicks On Seawater

Science.gov (United States)

The effectiveness of five solidifiers to remove Prudhoe Bay crude oil from artificial seawater in the laboratory was determined by ultraviolet-visible spectroscopy (UV-VIS) and gas chromatography/mass spectrometry (GC/MS). The performance of the solidifers was determined by US-V...

The formation of the two-way shape memory effect in rapidly quenched TiNiCu alloy under laser radiation

International Nuclear Information System (INIS)

Shelyakov, A V; Sitnikov, N N; Borodako, K A; Menushenkov, A P; Fominski, V Yu; Sheyfer, D V

2015-01-01

The effect of pulsed laser radiation (λ = 248 nm, τ = 20 ns) on structural properties and shape memory behavior of the rapidly quenched Ti 50 Ni 25 Cu 25 alloy ribbon was studied. The radiation energy density was varied from 2 to 20 mJ mm −2 . The samples were characterized by means of scanning electron microscopy, x-ray diffraction, microhardness measurements and shape memory bending tests. It was ascertained that the action of the laser radiation leads to the formation of a structural composite material due to amorphization or martensite modification in the surface layer of the ribbon. Two methods are proposed which allow one to generate the pronounced two-way shape memory effect (TWSME) in a local area of the ribbon by using only a single pulse of the laser radiation. With increasing energy density of laser treatment, the magnitude of the reversible angular displacement with realization of the TWSME increases. The developed techniques can be used for the creation of various micromechanical devices. (paper)

Effect of Rapid Solidification and Addition of Cu3P on the Mechanical Properties of Hypereutectic Al-Si Alloys

OpenAIRE

Suárez-Rosales,Miguel Ángel; Pinto-Segura,Raúl; Palacios-Beas,Elia Guadalupe; Hernández-Herrera,Alfredo; Chávez-Alcalá,José Federico

2016-01-01

The combined processes; rapid solidification, addition of Cu3P compound and heat treatments to improve the mechanical properties of the hypereutectic Al-13Si, Al-20Si and Al-20Si-1.5Fe-0.7Mn alloys (in wt. %) was studied. Optical microscopy and scanning electron microscopy were used to characterize the microstructures. The mechanical properties were evaluated by tensile tests. It was found that the cooling rate (20-50°C/s) used to solidify the alloys plus the addition of Cu3P compound favored...

Microstructure and wear properties of the electroslag remelting layer reinforced by TiC particles

Institute of Scientific and Technical Information of China (English)

无

2008-01-01

The electroslag remelting (ESR) layer reinforced by TiC particles was obtained by electroslag remelting.The microstructure and wear properties of the ESR layer were studied by means of scanning electron microscopy (SEM),X-ray diffraction (XRD),and wear test.The results indicate that TiC particles are synthesized by self-propagating high-temperature synthesis (SHS) reaction during the electroslag remelting process.The size of TiC particles is in the range of 1-10 μm,and the distribution of TiC particles is uniform,from outside to inside of the ESR layer,and the volume fraction and the size of TiC particles decrease gradually.Molten iron and slag flow into porosity due to the SHS process leading to rapid densification and the elimination of porosity in the ESR layer during the ESR process.TiC particles enhance the wear resistance of the ESR layer,whereas CaF2 can improve the high temperature lubricating property of the ESR layer.

Au-TiO2/Chit modified sensor for electrochemical detection of trace organophosphates insecticides.

Science.gov (United States)

Qu, Yunhe; Min, Hong; Wei, Yinyin; Xiao, Fei; Shi, Guoyue; Li, Xiaohua; Jin, Litong

2008-08-15

In this paper, Au-TiO2/Chit modified electrode was prepared with Au-TiO2 nanocomposite (Au-TiO2) and Chitosan (Chit) as a conjunct. The Au-TiO2 nanocomposite and the films were characterized by electrochemical and spectroscopy methods. A set of experimental conditions was also optimized for the film's fabrication. The electrochemical and electrocatalytic behaviors of Au-TiO2/Chit modified electrode to trace organophosphates (OPs) insecticides such as parathion were discussed in this work. By differential pulse voltammetry (DPV) measurement, the current responses of Au-TiO2/Chit modified electrode were linear with parathion concentration ranging from 1.0 ng/ml to 7.0 x 10(3)ng/ml with the detection limit of 0.5 ng/ml. In order to evaluate the performance of the detection system, we also examined the real samples successfully in this work. It exhibited a sensitive, rapid and easy-to-use method for the fast determination of trace OPs insecticides.

Production of low oxygen contamination orthorhombic Ti-Al-Nb intermetallic foil

International Nuclear Information System (INIS)

Gill, S.C.; Peters, J.A.; Blatter, P.; Jaquet, J.C.; Morris, M.A.

1996-01-01

Aerospace industries continue the search for high performance materials, and recent years have seen rapid developments being made in the capabilities of Ti-Al based intermetallic alloys. Interest in these alloys is caused by their attractive combination of strength and density, but major drawbacks include brittleness at low temperature and sensitivity to interstitial contamination. Development of a relatively new class of alloys was stimulated in 1988 by the discovery of Banerjee et al. of a Ti-Al-Nb orthorhombic (O) phase based on the Ti 2 AlNb composition. Some important applications for these alloys require the use of foil ( 2 phase and leads to material embrittlement. ELIT (Extra Low Interstitial Transfer) pack-rolling, developed by Sulzer Innotec, offers a technique to avoid oxygen contamination

Epoxidation of limonene over Ti MCM 41 and Ti BETA

International Nuclear Information System (INIS)

Cubillos Lobo, Jairo Antonio; Gonzalez Rodriguez, Lina Maria; Montes de Correa, Consuelo

2002-01-01

Ti MCM 41 were synthesized and evaluated in the epoxidation of limonene, using peroxide of hydrogen (H 2 O) as agent oxidizer. The characteristic hexagonal phase of Ti MCM 41 was obtained by heating the precursor gel during three days at 100 centigrade degrees. Further heating up to ten days leads to a decrease of this phase. The increase (Ti) in the synthesis gel also decreases that phase. The increase of Ti in the synthesis gel also decreases that phase UV VIS and FTIR spectroscopy indicates that Ti was incorporated in the lattice of Ti MCM 41 as well as, in Ti BETA. SEM micrographs of Ti MCM 41 show that the morphology changes with the Ti loading. Ti MCM 41 was most active than Ti BETA for limonene epoxidation even though both show high selectivity to epoxides

Microstructural evolution and wear behaviors of laser cladding Ti_2Ni/α(Ti) dual-phase coating reinforced by TiB and TiC

International Nuclear Information System (INIS)

Song, R.; Li, J.; Shao, J.Z.; Bai, L.L.; Chen, J.L.; Qu, C.C.

2015-01-01

Graphical abstract: - Highlights: • A TiC+TiB reinforced intermetallic matrix coating was fabricated by laser cladding. • The microstructural evolution of the reinforcements was analyzed. • A formula was established in term of wear loss, sliding time and applied load. • Wear behaviors were investigated by in situ continuing tests in different time intervals. • The transformation of wear mechanism at different applied loads was revealed. - Abstract: The Ti_2Ni/α(Ti) dual-phase coating reinforced by TiB and TiC was fabricated on the Ti6Al4V substrate by laser cladding. Phase constituents were confirmed by a theoretical prediction combined with X-ray diffraction (XRD) analyses. From the surface to the bottom of the coating, a regular evolution of the reinforcements’ microstructure, namely TiC_p+(TiB+TiC)_e, (TiB+TiC)_e and TiB_p+(TiB+TiC)_e (p and e were the abbreviations of primary and eutectic, respectively), was investigated by scanning electron microscopy (SEM). The coating possessed the higher microhardness than that of the substrate. An in situ dynamic method (in situ continuing tests at different time intervals) was designed to reveal wear behaviors at different wear stages. A quantitative calculation formula was established by a mathematic model to predict wear losses under different sliding time and applied loads in a definite precision. The wear mechanism was transformed from brittle debonding (at 10 N) to the joint action of brittle debonding and micro-cutting (at 20 N and 30 N) due to the microstructural evolution across the depth from the surface of the coating.

Microstructure of in-situ Synthesized (TiB+TiC)/Ti Composites Prepared by Hot-pressing

Institute of Scientific and Technical Information of China (English)

Zhenzhu ZHENG; Lin GENG; Honglin WANG; Weimin ZHOU; Hongyu XU

2003-01-01

In-situ 5 vol.pct TiB whiskers and TiC particulates reinforced Ti composites were fabricated by blending Ti powderand B4C particulates followed by reactive hot-pressing. The microstructure of the composites was investigated byusing differential scanning c

Stress analysis and microstructure of PVD monolayer TiN and multilayer TiN/(Ti,Al)N coatings

NARCIS (Netherlands)

Carvalho, NJM; Zoestbergen, E; Kooi, BJ; De Hosson, JTM

2003-01-01

Two PVD titanium nitride based coatings; monolayer TiN and multilayer resulting from the stacking of TiN and (Ti,Al)N layers were evaluated with respect to their stress state and microstructure. The TiN was deposited by triode evaporation ion plating, whereas the TiN/(Ti,AI)N was deposited using a

Short range order and phase separation in Ti-rich Ti-Al alloys

International Nuclear Information System (INIS)

Liew, H.J.

1999-01-01

of the reaction over a range of scales, from the atomic level on which order occurs through to large scale precipitates. Ti-15at%Al displays a phase separation mechanism involving both ordering and chemical phase decomposition which occurs in a time and temperature range that is readily accessible experimentally. Hence this alloy is an appropriate model system on which to conduct fundamental investigations into a complex decomposition mechanism and its kinetics. Both experimental and modelling results show that short range order develops rapidly in the alloy, and is followed by the formation and growth of congruent long range ordered regions of DO 19 structure. At a later stage composition variations form and increase in amplitude through a spinodal mechanism. From these findings, it cannot be ruled out that the observed decomposition sequence is due solely to the kinetics of ordering being more rapid than those of chemical phase separation. However, there are some indications which suggest that a thermodynamic criterion is operating, such that the onset of chemical phase separation occurs only after ordering has been achieved to some extent. The observed mechanism is fully consistent in appearance with the class of reactions known as conditional spinodals. (author)

Comparative analysis of mechanical characteristics of solidified concentrates from BWR system using Yugoslav and Italian cements

International Nuclear Information System (INIS)

Plecas, I.; Peric, A.; Drljaca, J.; Kostadinovic, A.

1987-01-01

In this paper, properties of Italian and Yugoslav cement mixture with BWR evaporation concentrates were compared, research was held upon fifteen samples, according to the adequate formulations. Samples were made in standard cube form, side 10 cm. Functional relationship between decreasing the compressive strength and amount of incorporated BWR concentrate cement mixture was developed. The results of research showed nearly the same mechanical properties of solidified BWR concentrate with Italian and Yugoslav cements. (author)

Glass formation and crystallization of Zr53Cu21Al10Ni8Ti8 alloy

International Nuclear Information System (INIS)

Neogy, S.; Tewari, R.; Srivastava, D.; Dey, G.K.; Banerjee, S.; Vaibhaw, K.; Ranganathan, S.

2010-01-01

In the present study, transmission electron microscopy techniques, like micro-diffraction, high resolution and fluctuation microscopy, have been employed to carry out detailed investigation of as-solidified and crystallized microstructures of the Zr 53 Cu 21 Al 10 Ni 8 Ti 8 alloy synthesized using melt spinning, suction casting and copper mould casting techniques. Samples produced by copper mould casting technique showed partially crystalline microstructure whereas the other techniques resulted in complete amorphous microstructures. High-resolution microscopy established that the dendrites of the big cube phase in partially crystalline glass grew by atomistic ledges. The other crystalline bct Zr 2 Ni phase, present in partially crystalline glass and also in all the crystallized microstructures, showed various types of internal faults depending upon the crystallite size. Fluctuation microscopy established that oxygen plays a major role in determining the degree of medium range order in glassy phases. In addition, variation in oxygen content changed the crystallization behaviour of glasses from a single to multiple events

Microstructure and Properties of (TiB2 + NiTi)/Ti Composite Coating Fabricated by Laser Cladding

Science.gov (United States)

Lin, Yinghua; Lei, Yongping; Fu, Hanguang; Lin, Jian

2015-10-01

Agglomerated TiB2 particle and network-like structure-reinforced titanium matrix composite coatings were prepared by laser cladding of the Ni + TiB2 + Ti preplaced powders on Ti-6Al-4V alloy. The network-like structure mainly consisted of NiTi and Ni3Ti. Through the experiment, it was found that the size of agglomerated particle gradually decreased with the increase of Ti content, but the number of the network-like structure first increased and then disappeared. In-situ reaction competition mechanism and the formation of network-like structure were discussed. The average micro-hardness gradually decreased with the increase of Ti content, but the average fracture toughness gradually increased. Meanwhile, the wear resistance of the coatings is higher than that of the substrate, but the wear loss of the coatings is gradually increased with the increase of Ti content.

Antibacterial activity and cell compatibility of TiZrN, TiZrCN, and TiZr-amorphous carbon coatings

Energy Technology Data Exchange (ETDEWEB)

Huang, Heng-Li [School of Dentistry, China Medical University, Taichung 404, Taiwan (China); Department of Bioinformatics and Medical Engineering, Asia University, Taichung 41354, Taiwan (China); Chang, Yin-Yu, E-mail: yinyu@nfu.edu.tw [Department of Mechanical and Computer-aided Engineering, National Formosa University, Yunlin 632, Taiwan (China); Liu, Jia-Xu [Department of Mechanical and Computer-aided Engineering, National Formosa University, Yunlin 632, Taiwan (China); Tsai, Ming-Tzu [Department of Biomedical Engineering, Hungkuang University, Taichung 433, Taiwan (China); Lai, Chih-Ho [Department of Microbiology and Immunology, Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan (China)

2015-12-01

A cathodic-arc evaporation system with plasma-enhanced duct equipment was used to deposit TiZrN, TiZrCN, and TiZr/a-C coatings. Reactive gases (N{sub 2} and C{sub 2}H{sub 2}) activated by the Ti and Zr plasma in the evaporation process was used to deposit the TiZrCN and TiZr/a-C coatings with different C and nitrogen contents. The crystalline structures and bonding states of coatings were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. The microbial activity of the coatings was evaluated against Staphylococcus aureus (Gram-positive bacteria) and Actinobacillus actinomycetemcomitans (Gram-negative bacteria) by in vitro antibacterial analysis using a fluorescence staining method employing SYTO9 and a bacterial-viability test on an agar plate. The cell compatibility and morphology related to CCD-966SK cell-line human skin fibroblast cells on the coated samples were also determined using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay, reverse-transcriptase-polymerase chain reaction, and scanning electron microscopy. The results suggest that the TiZrCN coatings not only possess better antibacterial performance than TiZrN and TiZr/a-C coatings but also maintain good compatibility with human skin fibroblast cells. - Highlights: • TiZrN, TiZrCN, and TiZr/a-C coatings were deposited using cathodic arc evaporation. • The TiZrCN showed a composite structure containing TiN, ZrN, and a-C. • The TiZrCN-coated Ti showed the least hydrophobicity among the samples. • The TiZrCN-coated Ti showed good human skin fibroblast cell viability. • The TiZrCN-coated Ti exhibited good antibacterial performance.

The properties of transparent TiO2 films for Schottky photodetector

Directory of Open Access Journals (Sweden)

Sung-Ho Park

2017-08-01

Full Text Available In this data, the properties of transparent TiO2 film for Schottky photodetector are presented for the research article, entitled as “High-performing transparent photodetectors based on Schottky contacts” (Patel et al., 2017 [1]. The transparent photoelectric device was demonstrated by using various Schottky metals, such as Cu, Mo and Ni. This article mainly shows the optical transmittance of the Ni-transparent Schottky photodetector, analyzed by the energy dispersive spectroscopy and interfacial TEM images for transparency to observe the interface between NiO and TiO2 film. The observation and analyses clearly show that no pinhole formation in the TiO2 film by Ni diffusion. The rapid thermal process is an effective way to form the quality TiO2 film formation without degradation, such as pinholes (Qiu et al., 2015 [2]. This thermal process may apply to form functional metal oxide layers for solar cells and photodetectors.

Soft-Template Synthesis of Mesoporous Anatase TiO₂ Nanospheres and Its Enhanced Photoactivity.

Science.gov (United States)

Li, Xiaojia; Zou, Mingming; Wang, Yang

2017-11-10

Highly crystalline mesoporous anatase TiO₂ nanospheres with high surface area (higher than P25 and anatase TiO₂) are prepared by a soft-template method. Despite the high specific surface area, these samples have three times lower equilibrium adsorption (<2%) than Degussa P25. The rate constant of the mesoporous anatase TiO₂ (0.024 min -1 ) reported here is 364% higher than that of P25 (0.0066 min -1 ), for the same catalytic loading. The results of oxidation-extraction photometry using several reactive oxygen species (ROS) scavengers indicated that mesoporous anatase TiO₂ generates more ROS than P25 under UV-light irradiation. This significant improvement in the photocatalytic performance of mesoporous spherical TiO₂ arises from the following synergistic effects in the reported sample: (i) high surface area; (ii) improved crystallinity; (iii) narrow pore wall thicknesses (ensuring the rapid migration of photogenerated carriers to the surface of the material); and (iv) greater ROS generation under UV-light.

The microstructure investigation of GeTi thin film used for non-volatile memory

International Nuclear Information System (INIS)

Shen Jie; Liu Bo; Song Zhitang; Xu Cheng; Liang Shuang; Feng Songlin; Chen Bomy

2008-01-01

GeTi thin film has been found to have the reversible resistance switching property in our previous work. In this paper, the microstructure of this material with a given composition was investigated. The film was synthesized by magnetron sputtering and treated by the rapid temperature process. The results indicate a coexist status of amorphous and polycrystalline states in the as-deposited GeTi film, and the grains in the film are extremely fine. Furthermore, not until the film annealed at 600 deg. C, can the polycrystalline state be detected by X-ray diffraction. Based on the morphological analysis, the sputtered GeTi has the column growth tendency, and the column structure vanishes with the temperature increasing. The microstructure and thermal property analysis indicate that GeTi does not undergo evident phase change process during the annealing process, which makes the switching mechanism of GeTi different from that of chalcogenide memory material, the most widely used phase change memory material

Independent control of metal cluster and ceramic particle characteristics during one-step synthesis of Pt/TiO2

DEFF Research Database (Denmark)

Schulz, H.; Madler, L.; Strobel, R.

2005-01-01

Rapid quenching during flame spray synthesis of Pt/TiO2 (0-10 Wt% Pt) is demonstrated as a versatile method for independent control of support (TiO2) and noble metal (Pt)cluster characteristics. Titania grain size, morphology, crystal phase structure, and crystal size were analyzed by nitrogen ad...

Microstructural and mechanical properties analysis of extruded Sn–0.7Cu solder alloy

Directory of Open Access Journals (Sweden)

Abdoul-Aziz Bogno

2015-01-01

Full Text Available The properties and performance of lead-free solder alloys such as fluidity and wettability are defined by the alloy composition and solidification microstructure. Rapid solidification of metallic alloys is known to result in refined microstructures with reduced microsegregation and improved mechanical properties of the final products as compared to normal castings. The rapidly solidified Sn-based solders by melt spinning were shown to be suitable for soldering with low temperature and short soldering duration. In the present study, rapidly solidified Sn–0.7 wt.%Cu droplets generated by impulse atomization (IA were achieved as well as directional solidification under transient conditions at lower cooling rate. This paper reports on a comparative study of the rapidly solidified and the directionally solidified samples. Different but complementary characterization techniques were used to fully analyze the solidification microstructures of the samples obtained under the two cooling regimes. These include X-ray diffractometry (XRD and scanning electron microscopy (SEM. In order to compare the tensile strength and elongation to fracture of the directionally solidified ingot and strip castings with the atomized droplet, compaction and extrusion of the latter were carried out. It was shown that more balanced and superior tensile mechanical properties are available for the hot extruded samples from compacted as-atomized Sn–0.7 wt.%Cu droplets. Further, elongation-to-fracture was 2–3× higher than that obtained for the directionally solidified samples.

Microtexture formation of Ni{sub 99}B{sub 1} alloys solidified on an ESL and an EML-a study based on the EBSP technique

Energy Technology Data Exchange (ETDEWEB)

Li Mingjun [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, Tsukuba Space Center, ISS Science Project Office, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 (Japan)], E-Mail: li.mingjun@aist.go.jp; Ishikawa, Takehiko [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, Tsukuba Space Center, ISS Science Project Office, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 (Japan); Nagashio, Kosuke [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, Sagamihara Campus, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Kuribayashi, Kazuhiko [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, Sagamihara Campus, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Yoda, Shinichi [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, Tsukuba Space Center, ISS Science Project Office, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 (Japan)

2007-03-25

We employed an electrostatic levitator (ESL) and an electromagnetic levitator (EML) to solidify Ni{sub 99}B{sub 1} (at.%) alloys at various undercoolings. The microstructures and microtextures were revealed by using the electron backscatter diffraction pattern (EBSP) technique in a scanning electron microscope. It is found that that no significant refinement can be identified at the low and medium undercooling regimes for the primary trunk in the sample solidified on the ESL, while the fragmentation of the secondary and even tertiary branches may take place to generate equiaxed grains. Further investigation by the EBSP reveals that neighboring grains have small misorientation angles, which may be ascribed to the absence of mechanical stirring from electromagnetic eddy current. A sharp contrast is that the samples solidified on the EML at low and medium undercoolings have refined equiaxed microstructures. The EBSP mapping reveals that the equiaxed grains yielded on the EML have a random distribution in crystallographic orientations among neighboring grains, indicating that electromagnetic stirring (EMS) induced by the electromagnetic field in the EML plays a vital role in promoting fragmentation and thus generating refined grains and random distribution in orientation. Regarding to the refined microstructure at high undercoolings, no significant difference arises in the samples processed between the EML and ESL.

Highly uniform bipolar resistive switching characteristics in TiO2/BaTiO3/TiO2 multilayer

International Nuclear Information System (INIS)

Ma, W. J.; Zhang, X. Y.; Wang, Ying; Zheng, Yue; Lin, S. P.; Luo, J. M.; Wang, B.; Li, Z. X.

2013-01-01

Nanoscale multilayer structure TiO 2 /BaTiO 3 /TiO 2 has been fabricated on Pt/Ti/SiO 2 /Si substrate by chemical solution deposition method. Highly uniform bipolar resistive switching (BRS) characteristics have been observed in Pt/TiO 2 /BaTiO 3 /TiO 2 /Pt cells. Analysis of the current-voltage relationship demonstrates that the space-charge-limited current conduction controlled by the localized oxygen vacancies should be important to the resistive switching behavior. X-ray photoelectron spectroscopy results indicated that oxygen vacancies in TiO 2 play a crucial role in the resistive switching phenomenon and the introduced TiO 2 /BaTiO 3 interfaces result in the high uniformity of bipolar resistive switching characteristics

Study of excited states in 48Ti, 49Ti and 50Ti by means of radiative neutron capture

International Nuclear Information System (INIS)

Ruyl, J.F.A.G.

1983-12-01

The γ radiation produced by thermal neutron capture in a natural Ti target and in enriched 47 Ti and 49 Ti targets has been investigated. In the analysis 57 excited states of 48 Ti, 28 of 49 Ti and 31 of 50 Ti have been identified. The values for the 48 Ti and 49 Ti neutron binding energy agree with previous data, the value for 50 Ti differs by five standard deviations. The nature of the neutron capture mechanism has been investigated by comparing the present results with those from previous (d,p) work. It appears that in 47 Ti capture proceeds through a doorway state and that the potential capture mechanism is valid for 48 Ti and 49 Ti. The Fermi gas model gives a good representation of the nuclear level density in all three nuclei. From a measurement of the γ-ray circular polarization resulting from the capture of polarized neutrons, combined with previous (d,p) work, the spins of five 49 Ti levels could be determined, and those of 13 other 49 Ti levels could be confirmed. The combination of nuclear orientation measurements and circular polarization measurements had yielded the unambiguous determination of the spins of one 48 Ti state and of five 50 Ti states. Further spin and parity determinations for six 48 Ti and for five 50 Ti states have been obtained from the analysis of the identified branches together with the results of previous experiments. Shell-model calculations, which yielded excitation energies, branching ratios, lifetimes and (d,p) spectroscopic factors, give a good representation of the experimental data for the low-lying states in both even-even nuclei. (Auth.)

Influence of electric current on microstructure evolution in Ti/Al and Ti/TiAl{sub 3} during spark plasma sintering

Energy Technology Data Exchange (ETDEWEB)

Sun, Y. [Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Haley, J. [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616-5294 (United States); Kulkarni, K. [Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208016, UP (India); Aindow, M. [Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Lavernia, E.J., E-mail: lavernia@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616-5294 (United States); Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697-2575 (United States)

2015-11-05

The synthesis of γ-TiAl from elemental metals via solid-state reactive diffusion processing routes involves multiple reaction steps with the formation of various intermediate intermetallic compounds, starting with TiAl{sub 3} because this phase is favored kinetically. To understand the processes by which the TiAl{sub 3} intermediate is eliminated during synthesis of γ-TiAl alloy via spark plasma sintering (SPS), the reaction between Ti and TiAl{sub 3} during SPS was studied with emphasis on the effects of the applied electric current and starting TiAl{sub 3} microstructure on the reaction kinetics and the underlying diffusion mechanisms. The intermediate intermetallic phases Ti{sub 3}Al, TiAl and TiAl{sub 2} were formed between the Ti and TiAl{sub 3} upon SPS processing at 900 °C. The applied electric current did not alter the character of the phases formation in the Ti/TiAl{sub 3} system, but thermodynamic calculations suggest that the activation energy for the nucleation of TiAl{sub 2} is reduced significantly with an electric current flowing. Moreover, the kinetics of the reactions between Ti and TiAl{sub 3} were enhanced when the starting TiAl{sub 3} microstructure was refined. The electric field also had a more significant influence on the grain growth kinetics for TiAl{sub 2} and TiAl in powder blend compacts with refined microstructures. - Highlights: • Reaction between Ti and TiAl{sub 3} during spark plasma sintering was studied. • Refined starting TiAl{sub 3} microstructure enhanced the reactions kinetics. • The nucleation barrier of TiAl{sub 2} was reduced by the applied electric field. • The applied electric field restrained the grain growth of TiAl and TiAl{sub 2}.

Microstructural evolution and wear behaviors of laser cladding Ti{sub 2}Ni/α(Ti) dual-phase coating reinforced by TiB and TiC

Energy Technology Data Exchange (ETDEWEB)

Song, R.; Li, J., E-mail: jacob_lijun@sina.com; Shao, J.Z.; Bai, L.L.; Chen, J.L.; Qu, C.C.

2015-11-15

Graphical abstract: - Highlights: • A TiC+TiB reinforced intermetallic matrix coating was fabricated by laser cladding. • The microstructural evolution of the reinforcements was analyzed. • A formula was established in term of wear loss, sliding time and applied load. • Wear behaviors were investigated by in situ continuing tests in different time intervals. • The transformation of wear mechanism at different applied loads was revealed. - Abstract: The Ti{sub 2}Ni/α(Ti) dual-phase coating reinforced by TiB and TiC was fabricated on the Ti6Al4V substrate by laser cladding. Phase constituents were confirmed by a theoretical prediction combined with X-ray diffraction (XRD) analyses. From the surface to the bottom of the coating, a regular evolution of the reinforcements’ microstructure, namely TiC{sub p}+(TiB+TiC){sub e}, (TiB+TiC){sub e} and TiB{sub p}+(TiB+TiC){sub e} (p and e were the abbreviations of primary and eutectic, respectively), was investigated by scanning electron microscopy (SEM). The coating possessed the higher microhardness than that of the substrate. An in situ dynamic method (in situ continuing tests at different time intervals) was designed to reveal wear behaviors at different wear stages. A quantitative calculation formula was established by a mathematic model to predict wear losses under different sliding time and applied loads in a definite precision. The wear mechanism was transformed from brittle debonding (at 10 N) to the joint action of brittle debonding and micro-cutting (at 20 N and 30 N) due to the microstructural evolution across the depth from the surface of the coating.

Influence of the thermal history of a particle during atomization on the morphology of carbides in a hypereutectic iron based alloy

International Nuclear Information System (INIS)

Kusý, M.; Behúlová, M.; Grgač, P.

2012-01-01

Highlights: ► Identification of solidification microstructures in RS powder from iron based alloy. ► Microstructures affected and nonaffected during the post-recalescence period. ► Thermokinetic newtonian model of rapid solidification of a droplet in gas atomization. ► Droplet thermal history and conditions for the microstructure development. ► Parameters influencing development of different solidification microstructures. - Abstract: Basic principles and consequences of the rapid solidification processing of melts have been successfully exploited in several progressive technologies of material production. In the paper, the solidification microstructures developed in the hypereutectic iron based alloy with the chemical composition of 3% C–3% Cr–12% V (wt.%) prepared by nitrogen gas atomization are presented and analysed. Several main types of solidification microstructures were identified in the rapidly solidified powder particles. According to the morphological features of carbide phases and computed thermal history of rapidly solidified particles, the microstructures were divided into two groups – microstructures morphologically non-affected during the post-recalescence period of solidification, and microstructures with morphological transitions occurring during the quasi-isothermal period of structure development. Based on the thermokinetic newtonian model of rapid solidification of a spherical droplet in the process of atomization, the thermal history of droplets with diameter from 20 μm to 400 μm rapidly solidified from different nucleation temperatures was studied. The thermo-physical conditions necessary for the development of variable microstructures in single rapidly solidified powder particles are predicted and discussed. The nucleation temperature, recalescence temperature and duration of quasi-isothermal plateau are supposed to be the most important parameters influencing the microstructure development in the rapidly solidified

Development of DNA biosensor based on TiO2 nanoparticles

Science.gov (United States)

Nadzirah, Sh.; Hashim, U.; Rusop, M.

2018-05-01

A novel technique of DNA hybridization on the TiO2 nanoparticles film was developed by dropping a single droplet of target DNA onto the surface of TiO2 for the study of various concentrations of target DNA. The surface of TiO2 nanoparticle film was functionalized with APTES and covalently immobilized with 1 µM probe DNA on the silanized TiO2 nanoparticles surface. The effect of silanization, immobilization and hybridization were quantitatively measured by the output current signal obtained using a picoammeter. The 1 µM target DNA was found to be the most effective target towards the 1 µM probe DNA as the output current signal was within range; while the output current signal of the 10 µM target DNA was observed to beyond the range of the probe DNA control due to the excessive concentration as compared to the probe DNA. This approach has several advantages such as rapid, simple, low cost, and sensitive current signal during detection of different target DNA concentrations.

Effect of nano-CeO2 on microstructure properties of TiC/TiN+nTi(CN) reinforced composite coating

International Nuclear Information System (INIS)

Jianing, Li; Chuanzhong, Chen; Cuifang, Zhang

2012-01-01

TiC/TiN+TiCN reinforced composite coatings were fabricated on Ti-6Al-4V alloy by laser cladding, which improved surface performance of the substrate. Nano-CeO 2 was able to suppress crystallization and growth of the crystals in the laser-cladded coating to a certain extent. With the addition of proper content of nano-CeO 2 , this coating exhibited fine microstructure. In this study, the Al 3 Ti+TiC/TiN+nano-CeO 2 laser-cladded coatings were studied by means of X-ray diffraction and scanning electron microscope. The X-ray diffraction results indicated that the Al 3 Ti+TiC/TiN+nano-CeO 2 laser-cladded coating consisted of Ti 3 Al, TiC, TiN, Ti 2 Al 20 Ce, TiC 0.3 N 0.7 , Ce(CN) 3 and CeO 2 , this phase constituent was beneficial to increase the microhardness and wear resistance of Ti-6Al-6V alloy. (author)

Water-driven micromotors for rapid photocatalytic degradation of biological and chemical warfare agents.

Science.gov (United States)

Li, Jinxing; Singh, Virendra V; Sattayasamitsathit, Sirilak; Orozco, Jahir; Kaufmann, Kevin; Dong, Renfeng; Gao, Wei; Jurado-Sanchez, Beatriz; Fedorak, Yuri; Wang, Joseph

2014-11-25

Threats of chemical and biological warfare agents (CBWA) represent a serious global concern and require rapid and efficient neutralization methods. We present a highly effective micromotor strategy for photocatalytic degradation of CBWA based on light-activated TiO2/Au/Mg microspheres that propel autonomously in natural water and obviate the need for external fuel, decontaminating reagent, or mechanical agitation. The activated TiO2/Au/Mg micromotors generate highly reactive oxygen species responsible for the efficient destruction of the cell membranes of the anthrax simulant Bacillus globigii spore, as well as rapid and complete in situ mineralization of the highly persistent organophosphate nerve agents into nonharmful products. The water-driven propulsion of the TiO2/Au/Mg micromotors facilitates efficient fluid transport and dispersion of the photogenerated reactive oxidative species and their interaction with the CBWA. Coupling of the photocatalytic surface of the micromotors and their autonomous water-driven propulsion thus leads to a reagent-free operation which holds a considerable promise for diverse "green" defense and environmental applications.

Tool geometry and damage mechanisms influencing CNC turning efficiency of Ti6Al4V

Science.gov (United States)

Suresh, Sangeeth; Hamid, Darulihsan Abdul; Yazid, M. Z. A.; Nasuha, Nurdiyanah; Ain, Siti Nurul

2017-12-01

Ti6Al4V or Grade 5 titanium alloy is widely used in the aerospace, medical, automotive and fabrication industries, due to its distinctive combination of mechanical and physical properties. Ti6Al4V has always been perverse during its machining, strangely due to the same mix of properties mentioned earlier. Ti6Al4V machining has resulted in shorter cutting tool life which has led to objectionable surface integrity and rapid failure of the parts machined. However, the proven functional relevance of this material has prompted extensive research in the optimization of machine parameters and cutting tool characteristics. Cutting tool geometry plays a vital role in ensuring dimensional and geometric accuracy in machined parts. In this study, an experimental investigation is actualized to optimize the nose radius and relief angles of the cutting tools and their interaction to different levels of machining parameters. Low elastic modulus and thermal conductivity of Ti6Al4V contribute to the rapid tool damage. The impact of these properties over the tool tips damage is studied. An experimental design approach is utilized in the CNC turning process of Ti6Al4V to statistically analyze and propose optimum levels of input parameters to lengthen the tool life and enhance surface characteristics of the machined parts. A greater tool nose radius with a straight flank, combined with low feed rates have resulted in a desirable surface integrity. The presence of relief angle has proven to aggravate tool damage and also dimensional instability in the CNC turning of Ti6Al4V.

Rapid photo-degradation of 2-chlorophenol under visible light irradiation using cobalt oxide-loaded TiO2/reduced graphene oxide nanocomposite from aqueous media.

Science.gov (United States)

Sharma, Ajit; Lee, Byeong-Kyu

2016-01-01

The photocatalytic removal of 2-chlorophenol (2-CP) from water environment was investigated by TiO2-RGO-CoO. Cobalt oxide-loaded TiO2 (TiO2-CoO) supported with reduced graphene oxide (RGO) was synthesized using a sol-gel method and then annealed at 500 °C for 5 min. The material characteristics were analyzed by UV-Vis analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Incorporation of cobalt oxide and RGO into the TiO2 system (TiO2-RGO-CoO) lowered the band gap energy to 2.83 eV, which greatly enhanced the visible light absorption. The TiO2-RGO-CoO photocatalyst showed complete removal of 20 mg/L 2-CP within 8 h with the addition of 0.01% H2O2 under 100 W visible light irradiation. The photo-degradation efficiency of 2-CP (10 mg/L) was 35.2, 48.9, 58.9 and 98.2% for TiO2, TiO2-RGO, TiO2-CoO and TiO2-RGO-CoO, respectively, in the presence of visible light irradiation at solution pH of 6.0. The TiO2-RGO-CoO photocatalyst retained its high removal efficiency even after five photocatalytic cycles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Deposit of thin films of TiN, a-C, Ti/TiN/a-C by laser ablation; Deposito de peliculas delgadas de TiN, a-C, Ti/TiN/a-C por ablacion laser

Energy Technology Data Exchange (ETDEWEB)

Mejia, I.S.; Escobar A, L.; Camps, E.; Romero, S. [ININ, 52045 Ocoyoacac, Estado de mexico (Mexico); Muhl, S. [IIM, UNAM, A.P. 364, 01000 Mexico D.F. (Mexico)

2006-07-01

Thin films of titanium nitride (TiN), amorphous carbon (a-C), as well as bilayers of Ti/TiN/a-C were deposited by means of the laser ablation technique. It was investigated the effect that it has the laser fluence used to ablation the targets in the structure and mechanical properties of the TiN deposited films. The TiN obtained films have a preferential orientation in the direction (200). The results show that the hardness of this material is influenced by the laser fluence. It is observed that the hardness is increased in an approximately lineal way with the increment of the fluence up to 19 J/cm{sup 2}. The films of amorphous carbon present hardness of the order of 11.2 GPa. Likewise it was found that the multilayers of Ti/TiN/aC presented a bigger hardness that of its individual components. (Author)

JINR rapid communications

International Nuclear Information System (INIS)

1995-01-01

The present collection of rapid communications from JINR, Dubna, contains eight separate reports on the measurement of charge radii for Ti nuclei, spectroscopy of 13 Be, concentrations of hadrons and quark-gluon plasma in mixed phase, experimental results on one-spin pion asymmetry in the d↑ + A → π±(90 0 ) + X process, new results on cumulative pion and proton production in p-D collisions, investigation of charge exchange reactions, the study of the tensor analyzing power in cumulative particle production on a deuteron beam and an evidence for the excited states of the S = -2 stable light dibaryon. 32 figs., 6 tabs

Analysis of diamond-like carbon and Ti/MoS2 coatings on Ti-6Al-4V substrates for applicability to turbine engine applications

International Nuclear Information System (INIS)

Wu, L.; Holloway, B.C.; Kalil, C.; Manos, D.M.

2000-01-01

Ti-6Al-4V substrates have been coated by diamond-like carbon (DLC) films, with no surface pretreatment, and have been coated by Ti/MoS 2 films, with a simple surface pre-cleaning. The DLC films were deposited by planar coil r.f. inductively-coupled plasma-enhanced chemical vapor deposition (r.f. ICPECVD); the Ti/MoS 2 films were deposited by magnetron sputtering. Both the DLC and Ti/MoS 2 films were characterized by pull tests, hardness tests, scanning electron microscopy (SEM), and wear tests (pin-on-disk and block-on-ring) to compare their adhesion, hardness, surface topology, and wear properties to plasma-sprayed Cu-Ni-In coating currently used for turbine engine applications. The DLC films were easily characterized by their optical properties because they were highly transparent. We used variable-angle spectroscopic ellipsometry (VASE) to characterize thickness and to unequivocally extract real and complex index of refraction, providing a rapid assessment of film quality. Thicker coatings yielded the largest hardness values. The DLC coatings did not require abrasive pretreatment or the formation of bond-layers to ensure good adhesion to the substrate. Simple surface pre-cleaning was also adequate to form well-adhered Ti/MoS 2 on Ti-6Al-4V. The results show that the DLC and Ti/MoS 2 coatings are both much better fretting- and wear-resistant coatings than plasma-sprayed Cu-Ni-In. Both show excellent adhesion to the substrates, less surface roughness, harder surfaces, and more wear resistance than the Cu-Ni-In films. (orig.)

Dispersion strengthening of precipitation hardened Al-Cu-Mg alloys prepared by rapid solidification and mechanical alloying

Science.gov (United States)

Gilman, P. S.; Sankaran, K. K.

1988-01-01

Several Al-4Cu-1Mg-1.5Fe-0.75Ce alloys have been processed from either rapidly solidified or mechanically alloyed powder using various vacuum degassing parameters and consolidation techniques. Strengthening by the fine subgrains, grains, and the dispersoids individually or in combination is more effective when the alloys contain shearable precipitates; consequently, the strength of the alloys is higher in the naturally aged rather than the artificially aged condition. The strengths of the mechanically alloyed variants are greater than those produced from prealloyed powder. Properties and microstructural features of these dispersion strengthened alloys are discussed in regards to their processing histories.

A study on wear resistance and microcrack of the Ti3Al/TiAl + TiC ceramic layer deposited by laser cladding on Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Li Jianing; Chen Chuanzhong; Squartini, Tiziano; He Qingshan

2010-01-01

Laser cladding of the Al + TiC alloy powder on Ti-6Al-4V alloy can form the Ti 3 Al/TiAl + TiC ceramic layer. In this study, TiC particle-dispersed Ti 3 Al/TiAl matrix ceramic layer on the Ti-6Al-4V alloy by laser cladding has been researched by means of X-ray diffraction, scanning electron microscope, electron probe micro-analyzer, energy dispersive spectrometer. The main difference from the earlier reports is that Ti 3 Al/TiAl has been chosen as the matrix of the composite coating. The wear resistance of the Al + 30 wt.% TiC and the Al + 40 wt.% TiC cladding layer was approximately 2 times greater than that of the Ti-6Al-4V substrate due to the reinforcement of the Ti 3 Al/TiAl + TiC hard phases. However, when the TiC mass percent was above 40 wt.%, the thermal stress value was greater than the materials yield strength limit in the ceramic layer, the microcrack was present and its wear resistance decreased.

Study of the preparation of Cu-TiC composites by reaction of soluble Ti and ball-milled carbon coating TiC

Science.gov (United States)

Xu, Xuexia; Li, Wenbin; Wang, Yong; Dong, Guozhen; Jing, Shangqian; Wang, Qing; Feng, Yanting; Fan, Xiaoliang; Ding, Haimin

2018-06-01

In this work, Cu-TiC composites have been successfully prepared by reaction of soluble Ti and carbon coating TiC. Firstly, the ball milling of graphite and TiC mixtures is used to obtain the carbon coating TiC which has fine size and improved reaction activity. After adding the ball milled carbon coating TiC into Cu-Ti melts, the soluble Ti will easily react with the carbon coating to form TiC. This process will also improve the wettability between Cu melts and TiC core. As a result, besides the TiC prepared by reaction of soluble Ti and carbon coating, the ball milled TiC will also be brought into the melts. Some of these ball-milled TiC particles will go on being coated by the formed TiC from the reaction of Ti and the coating carbon and left behind in the composites. However, most of TiC core will be further reacted with the excessive Ti and be transformed into the newly formed TiC with different stoichiometry. The results indicate that it is a feasible method to synthesize TiC in Cu melts by reaction of soluble Ti and ball-milled carbon coating TiC.

The martensitic transformation in Ti-rich TiNi shape memory alloys

International Nuclear Information System (INIS)

Lin, H.C.; Wu, S.K.; Lin, J.C.

1994-01-01

The martensitic (Ms) transformation temperatures and their ΔH values of Ti 51 Ni 49 and Ti 50.5 Ni 49.5 alloys are higher than those of equiatomic or Ni-rich TiNi alloys. The Ti-rich TiNi alloys exhibit good shape recovery in spite of a great deal of second phase Ti 2 Ni or Ti 4 Ni 2 O existing around B2 grain boundaries. The nearly identical transformation temperatures indicate that the absorbed oxygen in Ti-rich TiNi alloys may react with Ti 2 Ni particles, instead of the TiNi matrix, to form Ti 4 Ni 2 O. Martensite stabilization can be induced by cold rolling at room temperature. Thermal cycling can depress the transformation temperatures significantly, especially in the initial 20 cycles. The R-phase transformation can be promoted by both cold rolling and thermal cycling in Ti-rich TiNi alloys due to introduced dislocations depressing the Ms temperature. The strengthening effects of cold rolling and thermal cycling on the Ms temperature of Ti-rich TiNi alloys are found to follow the expression Ms = To - KΔσ y . The K values are affected by different strengthening processes and related to the as-annealed transformation temperatures. The higher the as-annealed Ms (or As), the larger the K value. (orig.)

Multilayer TiC/TiN diffusion barrier films for copper

International Nuclear Information System (INIS)

Yoganand, S.N.; Raghuveer, M.S.; Jagannadham, K.; Wu, L.; Karoui, A.; Rozgonyi, G.

2002-01-01

TiC/TiN thin films deposited by reactive magnetron sputtering on Si (100) substrates were investigated by transmission electron microscopy for microstructure and by deep level transient spectroscopy (DLTS) for diffusion barrier against copper. TiN thin films deposited on Si substrates at a substrate temperature of 600 deg. C were textured, and TiC thin films deposited at the same temperature were polycrystalline. TiC/TiN multilayer films also showed the same characteristics with the formation of an additional interaction layer. The diffusion barrier characteristics of the TiC/TiN/Si were determined by DLTS and the results showed that the films completely prevented diffusion of copper into Si

Reactive spark plasma synthesis of CaZrTi2O7 zirconolite ceramics for plutonium disposition

Science.gov (United States)

Sun, Shi-Kuan; Stennett, Martin C.; Corkhill, Claire L.; Hyatt, Neil C.

2018-03-01

Near single phase zirconolite ceramics, prototypically CaZrTi2O7, were fabricated by reactive spark plasma sintering (RSPS), from commercially available CaTiO3, ZrO2 and TiO2 reagents, after processing at 1200 °C for only 1 h. Ceramics were of theoretical density and formed with a controlled mean grain size of 1.9 ± 0.6 μm. The reducing conditions of RSPS afforded the presence of paramagnetic Ti3+, as demonstrated by EPR spectroscopy. Overall, this study demonstrates the potential for RSPS to be a disruptive technology for disposition of surplus separated plutonium stockpiles in ceramic wasteforms, given its inherent advantage of near net shape products and rapid throughput.

The Influence of a TiN Film on the Electronic Contribution to the Thermal Conductivity of a TiC Film in a TiN-TiC Layer System

Science.gov (United States)

Jagannadham, K.

2018-01-01

TiC and TiN films were deposited by reactive magnetron sputtering on Si substrates. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization of the microstructure and interface structure have been carried out and the stoichiometric composition of TiC is determined. Thermal conductivity and interface thermal conductance between different layers in the films are evaluated by the transient thermo reflectance (TTR) and three-omega (3- ω) methods. The results showed that the thermal conductivity of the TiC films increased with temperature. The thermal conductivity of TiC in the absence of TiN is dominated by phonon contribution. The electronic contribution to the thermal conductivity of TiC in the presence of TiN is found to be more significant. The interface thermal conductance of the TiC/TiN interface is much larger than that of interfaces at Au/TiC, TiC/Si, or TiN/Si. The interface thermal conductance between TiC and TiN is reduced by the layer formed as a result of interdiffusion.

Synthesis, microstructure and mechanical properties of Ti3SiC2-TiC composites pulse discharge sintered from Ti/Si/TiC powder mixture

International Nuclear Information System (INIS)

Tian Wubian; Sun Zhengming; Hashimoto, Hitoshi; Du Yulei

2009-01-01

Ti 3 SiC 2 -TiC composites with the volume fractions of TiC from 0 to 90% were fabricated by pulse discharge sintering (PDS) technique using Ti-Si-TiC as starting powders in the sintering temperature range of 1250-1400 deg. C. Phase content and microstructure of the synthesized samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The samples sintered at 1400 deg. C are almost fully dense for all compositions with relative density higher than 98%. The phase distribution in the synthesized samples is non-uniform. The Vickers hardness increases almost linearly with the volume fraction of TiC up to a value of 20.1 ± 1.4 GPa at 90 vol.% TiC. The flexural strength increases with the volume fraction of TiC to a maximum value of 655 ± 10 MPa at 50 vol.% TiC. The relationship between microstructure and mechanical properties is discussed.

Experimental study on the leaching of radioactive materials from radioactive wastes solidified in cement into sea water. Part 2

International Nuclear Information System (INIS)

Hatta, H.; Ono, H.; Nagakura, T.; Machida, T.; Seki, T.; Maki, Y.

Results are presented from the study on leachability of 60 Co and 137 Cs from BWR concentrated wastes that had been solidified in cement. The leachability of 60 Co is very small compared to that of 137 Cs and varies greatly with the type of leaching medium. The effect of duration of immersion on leachability is comparatively large

Directed laser processing of compacted powder mixtures Al2O3-TiO2-Y2O3

Directory of Open Access Journals (Sweden)

Vlasova M.

2013-01-01

Full Text Available The phase formation, microstructure and surface texture of laser treated ternary powder mixtures of Al2O3-TiO2-Y2O3 had been studied. Rapid high temperature heating and subsequent rapid cooling due to the directed movement of the laser beam forms concave ceramic tracks. Phase composition and microstructure of the tracks depends on the Al2O3 content and the TiO2/Y2O3 ratio of the initial mixtures. The main phases observed are Y3Al5O12, Y2Ti2O7, Al2O3 and Al2TiO5. Due to the temperature gradient in the heating zone, complex layered structures are formed. The tracks consist of three main layers: a thin surface layer, a layer of crystallization products of eutectic alloys, and a lower sintered layer. The thickness of the crystallization layer and the shrinkage of the irradiation zone depend on the amount of Y3Al5O12 and Al2O3 crystallized from the melt.

Cellulose Acetate/N-TiO2 Biocomposite Flexible Films with Enhanced Solar Photochromic Properties

Science.gov (United States)

Radhika, T.; Anju, K. R.; Silpa, M. S.; Ramalingam, R. Jothi; Al-Lohedan, Hamad A.

2017-07-01

Flexible cellulose acetate/N-TiO2 nanocomposite films containing various concentrations of nanosized N-TiO2 and an intelligent methylene blue ink have been prepared by solution casting. The hydrothermally prepared nitrogen-doped titania (N-TiO2) and the films were characterized in detail. The photochromic properties of the prepared films were investigated under ultraviolet (UV), visible light, and simulated solar irradiation by UV-Vis spectrophotometry. Upon irradiation, the films exhibited rapid photochromic response that was reversible at room temperature. Films with higher content of nano N-TiO2 showed enhanced decoloration/recoloration under all irradiation conditions, with fast decoloration/recoloration under simulated solar irradiation. These results suggest that the amount of nano N-TiO2 in the composite, the concentration of methylene blue, and the solvent greatly influence the photochromic properties of the films. Such flexible and transparent cellulose acetate/N-TiO2 films with enhanced decoloration/recoloration properties under solar irradiation are promising smart materials for use in photoreversible printed electronics applications.

Influence of carbonation on the acid neutralization capacity of cements and cement-solidified/stabilized electroplating sludge.

Science.gov (United States)

Chen, Quanyuan; Zhang, Lina; Ke, Yujuan; Hills, Colin; Kang, Yanming

2009-02-01

Portland cement (PC) and blended cements containing pulverized fuel ash (PFA) or granulated blast-furnace slag (GGBS) were used to solidify/stabilize an electroplating sludge in this work. The acid neutralization capacity (ANC) of the hydrated pastes increased in the order of PC > PC/GGBS > PC/PFA. The GGBS or PFA replacement (80 wt%) reduced the ANC of the hydrated pastes by 30-50%. The ANC of the blended cement-solidified electroplating sludge (cement/sludge 1:2) was 20-30% higher than that of the hydrated blended cement pastes. Upon carbonation, there was little difference in the ANC of the three cement pastes, but the presence of electroplating sludge (cement/sludge 1:2) increased the ANC by 20%. Blended cements were more effective binders for immobilization of Ni, Cr and Cu, compared with PC, whereas Zn was encapsulated more effectively in the latter. Accelerated carbonation improved the immobilization of Cr, Cu and Zn, but not Ni. The geochemical code PHREEQC, with the edited database from EQ3/6 and HATCHES, was used to calculate the saturation index and solubility of likely heavy metal precipitates in cement-based solidification/stabilization systems. The release of heavy metals could be related to the disruption of cement matrices and the remarkable variation of solubility of heavy metal precipitates at different pH values.

Leach studies on cement-solidified ion exchange resins from decontamination processes at operating nuclear power stations

International Nuclear Information System (INIS)

McIsaac, C.V.; Akers, D.W.; McConnell, J.W.; Morcos, N.

1992-01-01

The effects of varying pH and leachant compositions on the physical stability and leachability of radionuclides and chelating agents were determined for cement-solidified decontamination ion-exchange resin wastes collected from two operating commercial light water reactors. Small scale waste-form specimens were collected during waste solidifications performed at the Brunswick Steam Electric Plant Unit 1 and at the James A. FitzPatrick Nuclear Power Station. The collected specimens were leach tested, and their compressive strength was measured in accordance with the Nuclear Regulatory Commission's ''Technical Position on Waste Form'' (Revision 1), from the Low-Level Waste Management Branch. Leachates from these studies were analyzed for radionuclides, selected transition metals, and chelating agents to assess the leachability of these waste form constituents. Leachants used for the study were deionized water, simulated seawater, and groundwater compositions similar to those found at Barnwell, South Carolina and Hanford, Washington. Results of this study indicate that initial leachant pH does not affect leachate pH or releases from cement-solidified decontamination ion-exchange resin waste forms. However, differences in leachant composition and the presence of chelating agents may affect the releases of radionuclides and chelating agents. In addition, results from this study indicate that the cumulative releases of radionuclides and chelating agents observed for forms that disintegrated were similar to those for forms that maintained their general physical integrity

Synthesis of magnetic graphene oxide–TiO{sub 2} and their antibacterial properties under solar irradiation

Energy Technology Data Exchange (ETDEWEB)

Chang, Ying-Na [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Ou, Xiao-Ming [China National Engineering Research Center for Agrochemicals, Hunan Research Institute of Chemical Industry, Changsha 410014 (China); Zeng, Guang-Ming [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Gong, Ji-Lai, E-mail: jilaigong@gmail.com [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Deng, Can-Hui; Jiang, Yan; Liang, Jie; Yuan, Gang-Qiang; Liu, Hong-Yu; He, Xun [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China)

2015-07-15

Highlights: • Magnetic graphene oxide–TiO{sub 2} (MGO–TiO{sub 2}) composites were synthesized. • MGO–TiO{sub 2} had excellent antibacterial activity toward Escherichia coli. • MGO–TiO{sub 2} could effectively and rapidly separate from aqueous solution. • Carbonates and phosphates significantly reduced the bacterial survival rate. - Abstract: Titanium dioxide (TiO{sub 2}) has been intensively researched and increasingly used as antibacterial agent, but it suffers from separation inconvenience. Its effective removal from water after reaction while maintaining its high antibacterial activity becomes necessary. In this work, it was the first time the magnetic graphene oxide–TiO{sub 2} (MGO–TiO{sub 2}) composites were prepared through a simple synthesis method. The results indicated that MGO–TiO{sub 2} exhibited a good antibacterial activity against Escherichia coli. MGO–TiO{sub 2} was found to almost completely inactivate the E. coli within 30 min under solar irradiation. The effect of inorganic ions present in E. coli suspension was also evaluated. Compared with other ions, HCO{sub 3}{sup −} and HPO{sub 4}{sup 2−} had a greater influence on the antibacterial property.

Preparation of MoS2/TiO2 based nanocomposites for photocatalysis and rechargeable batteries: progress, challenges, and perspective.

Science.gov (United States)

Chen, Biao; Meng, Yuhuan; Sha, Junwei; Zhong, Cheng; Hu, Wenbin; Zhao, Naiqin

2017-12-21

The rapidly increasing severity of the energy crisis and environmental degradation are stimulating the rapid development of photocatalysts and rechargeable lithium/sodium ion batteries. In particular, MoS 2 /TiO 2 based nanocomposites show great potential and have been widely studied in the areas of both photocatalysis and rechargeable lithium/sodium ion batteries due to their superior combination properties. In addition to the low-cost, abundance, and high chemical stability of both MoS 2 and TiO 2 , MoS 2 /TiO 2 composites also show complementary advantages. These include the strong optical absorption of TiO 2 vs. the high catalytic activity of MoS 2 , which is promising for photocatalysis; and excellent safety and superior structural stability of TiO 2 vs. the high theoretic specific capacity and unique layered structure of MoS 2 , thus, these composites are exciting as anode materials. In this review, we first summarize the recent progress in MoS 2 /TiO 2 -based nanomaterials for applications in photocatalysis and rechargeable batteries. We highlight the synthesis, structure and mechanism of MoS 2 /TiO 2 -based nanomaterials. Then, advancements and strategies for improving the performance of these composites in photocatalytic degradation, hydrogen evolution, CO 2 reduction, LIBs and SIBs are critically discussed. Finally, perspectives on existing challenges and probable opportunities for future exploration of MoS 2 /TiO 2 -based composites towards photocatalysis and rechargeable batteries are presented. We believe the present review would provide enriched information for a deeper understanding of MoS 2 /TiO 2 composites and open avenues for the rational design of MoS 2 /TiO 2 based composites for energy and environment-related applications.

Large ferroelectric polarization of TiN/Hf0.5Zr0.5O2/TiN capacitors due to stress-induced crystallization at low thermal budget

Science.gov (United States)

Kim, Si Joon; Narayan, Dushyant; Lee, Jae-Gil; Mohan, Jaidah; Lee, Joy S.; Lee, Jaebeom; Kim, Harrison S.; Byun, Young-Chul; Lucero, Antonio T.; Young, Chadwin D.; Summerfelt, Scott R.; San, Tamer; Colombo, Luigi; Kim, Jiyoung

2017-12-01

We report on atomic layer deposited Hf0.5Zr0.5O2 (HZO)-based capacitors which exhibit excellent ferroelectric (FE) characteristics featuring a large switching polarization (45 μC/cm2) and a low FE saturation voltage (˜1.5 V) as extracted from pulse write/read measurements. The large FE polarization in HZO is achieved by the formation of a non-centrosymmetric orthorhombic phase, which is enabled by the TiN top electrode (TE) having a thickness of at least 90 nm. The TiN films are deposited at room temperature and annealed at 400 °C in an inert environment for at least 1 min in a rapid thermal annealing system. The room-temperature deposited TiN TE acts as a tensile stressor on the HZO film during the annealing process. The stress-inducing TiN TE is shown to inhibit the formation of the monoclinic phase during HZO crystallization, forming an orthorhombic phase that generates a large FE polarization, even at low process temperatures.

Numerical Simulation of Spheroidization Process of TiAl Alloy Powders in Radio Frequency Plasma

OpenAIRE

ZHU Langping; LU Xin; LIU Chengcheng; LI Jianchong; NAN Hai

2017-01-01

A numerical simulation method was used to study the radio frequency plasma spheroidization process of TiAl alloy powder. The effects of velocity field and temperature field on the motion trajectory and mass change of TiAl alloy powder with different particle size were analyzed.The results show that the temperature of powder particles increases rapidly under high temperature plasma, surface evaporation cause the reduction of particle size, and particles with small size tend to evaporate quickl...

First-Principles Study of the Polar TiC/Ti Interface

Institute of Scientific and Technical Information of China (English)

Limin LIU; Shaoqing WANG; Hengqiang YE

2003-01-01

The interface structure, work of adhesion, and bonding character of the polar TiC/Ti interface have been examined by the first-principles density functional plane-wave pseudopotential calculations. Both Ti- and C-terminated interfaces including six different interface structures were calculated, which present quite different features. For the Ti-terminated interface, the interfacial Ti-Ti bond has a strong metallic and weak covalent character; while for the C-terminated interface, the interfacial bond is a strong polar covalent interaction between the Ti-3d and C-2p orbital.The work of adhesion of C-terminated interface is nearly 9 J/m2 stronger than that of the Ti-terminated. It is found that each termination has relatively large work of adhesion, which is consistent with other polar interfaces.

A study on wear resistance and microcrack of the Ti{sub 3}Al/TiAl + TiC ceramic layer deposited by laser cladding on Ti-6Al-4V alloy

Energy Technology Data Exchange (ETDEWEB)

Li Jianing, E-mail: ljnljn1022@163.com [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Chen Chuanzhong [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Squartini, Tiziano [INFM-Department of Physics, Siena University, Siena 53100 (Italy); He Qingshan [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China)

2010-12-15

Laser cladding of the Al + TiC alloy powder on Ti-6Al-4V alloy can form the Ti{sub 3}Al/TiAl + TiC ceramic layer. In this study, TiC particle-dispersed Ti{sub 3}Al/TiAl matrix ceramic layer on the Ti-6Al-4V alloy by laser cladding has been researched by means of X-ray diffraction, scanning electron microscope, electron probe micro-analyzer, energy dispersive spectrometer. The main difference from the earlier reports is that Ti{sub 3}Al/TiAl has been chosen as the matrix of the composite coating. The wear resistance of the Al + 30 wt.% TiC and the Al + 40 wt.% TiC cladding layer was approximately 2 times greater than that of the Ti-6Al-4V substrate due to the reinforcement of the Ti{sub 3}Al/TiAl + TiC hard phases. However, when the TiC mass percent was above 40 wt.%, the thermal stress value was greater than the materials yield strength limit in the ceramic layer, the microcrack was present and its wear resistance decreased.

Fretting wear behaviour of TiC/Ti(C,N)/TiN multi-layer coatings at elevated temperature in gross slip regime

International Nuclear Information System (INIS)

Liu Hanwei; Huang Kunpeng; Zhu Minhao; Zhou Zhongrong

2005-01-01

Tic/Ti(C,N)/TiN multi-layer coatings are prepared on the 1Cr13 stainless steel substrate by the technique of Chemical Vapour Deposition, and the fretting wear behaviour of 1Cr13 stainless steel and TiC/Ti(C,N)/TiN coatings are investigated and studied controversially from 25 degree C to 400 degree C in the gross slip regime. It shows that the temperature has great influence on the fretting wear in the gross slip regime for the 1Cr13 stainless steel but little for Ti/C/Ti(C,N)/TiN multi-layer coatings. With the temperature increasing, the friction coefficient and the wear volume of the 1Cr13 alloy decreases and the wear volume of TiC/Ti(C, N)/TiN multi-layer coatings is invariant. TiC/Ti(C,N)/TiN multi-layer coatings have better wear-resistant capability than the 1Cr13 stainless steel, but the wear volume of the substrate increases greatly because of the grain-abrasion resulted from hard debris when TiC/Ti(C,N)/TiN multi-layer coatings are ground off. (authors)

Tailoring ultrafine grained and dispersion-strengthened Ti 2 AlC/TiAl ...

Indian Academy of Sciences (India)

In situ Ti 2 AlC/TiAl composite was fabricated by hot-pressing method via the reaction system of Ti 3 AlC 2 and Ti-Al pre-alloyed powders at low temperature of 1150 ∘ C. The composite mainly consisted of TiAl, Ti 3 Al and Ti 2 AlC phases. Fine Ti 2 AlC particles were homogeneously distributed and dispersed in the matrix.

Structure, phase composition and microhardness of vacuum-arc multilayered Ti/Al, Ti/Cu, Ti/Fe, Ti/Zr nano-structures with different periods

Energy Technology Data Exchange (ETDEWEB)

Demchishin, A.V., E-mail: ademch@meta.ua [Institute of Problems in Material Science, NASU, Kiev (Ukraine); Gnilitskyi, I., E-mail: iaroslav.gnilitskyi@unimore.it [DISMI – Department of Sciences and Methods for Engineering, University of Modena and Reggio Emilia, Reggio Emilia (Italy); Orazi, L., E-mail: leonardo.orazi@unimore.it [DISMI – Department of Sciences and Methods for Engineering, University of Modena and Reggio Emilia, Reggio Emilia (Italy); Ascari, A., E-mail: a.ascari@unibo.it [DIN – Department of Industrial Engineering, University of Bologna, Bologna (Italy)

2015-07-01

Highlights: • Multilayer coatings of Ti/Fe, Ti/Al, Ti/Cu and Ti/Zr are generated. • Microstructure and morphology of the different systems are investigated. • XR diffraction analysis was performed to investigate phases composition. • Effects of inter metallic phases on microhardess are investigated. • Correlations between parameters and layer thickness are outlined. - Abstract: The microstructure, phase composition and microhardness of multilayered Ti/Al, Ti/Cu, Ti/Fe and Ti/Zr condensates produced on stainless steel substrates via vacuum-arc evaporation of pure metals were studied. The sublayer periods (Λ) were regulated in the range 80–850 nm by varying the vacuum discharge current and the duration of the successive depositions of metallic plasma onto the substrates while maintaining the total deposition time constant. The regularity of the obtained nanostructures was investigated by scanning and transmission electron microscopy while phase compositions were identified with X-ray diffraction (XRD) analysis in order to evidence the presence of interdiffusion and the amount of intermetallics. Condensates cross sections were mechanically characterized by means of microhardness tests. Measurements were correlated to the periods and to the presence of intermetallics.

Structure, phase composition and microhardness of vacuum-arc multilayered Ti/Al, Ti/Cu, Ti/Fe, Ti/Zr nano-structures with different periods

International Nuclear Information System (INIS)

Demchishin, A.V.; Gnilitskyi, I.; Orazi, L.; Ascari, A.

2015-01-01

Highlights: • Multilayer coatings of Ti/Fe, Ti/Al, Ti/Cu and Ti/Zr are generated. • Microstructure and morphology of the different systems are investigated. • XR diffraction analysis was performed to investigate phases composition. • Effects of inter metallic phases on microhardess are investigated. • Correlations between parameters and layer thickness are outlined. - Abstract: The microstructure, phase composition and microhardness of multilayered Ti/Al, Ti/Cu, Ti/Fe and Ti/Zr condensates produced on stainless steel substrates via vacuum-arc evaporation of pure metals were studied. The sublayer periods (Λ) were regulated in the range 80–850 nm by varying the vacuum discharge current and the duration of the successive depositions of metallic plasma onto the substrates while maintaining the total deposition time constant. The regularity of the obtained nanostructures was investigated by scanning and transmission electron microscopy while phase compositions were identified with X-ray diffraction (XRD) analysis in order to evidence the presence of interdiffusion and the amount of intermetallics. Condensates cross sections were mechanically characterized by means of microhardness tests. Measurements were correlated to the periods and to the presence of intermetallics

Structure of electron collection electrode in dye-sensitized nanocrystalline TiO2

International Nuclear Information System (INIS)

Yanagida, Masatoshi; Numata, Youhei; Yoshimatsu, Keiichi; Ochiai, Masayuki; Naito, Hiroyoshi; Han, Liyuan

2013-01-01

As part of the effort to control electron transport in the TiO 2 films of dye-sensitized solar cells (DSCs), the structure of the electron collection electrode on the films has been investigated. Here, we report the comparison between a sandwich-type dye-sensitized solar cell (SW-DSC), in which the TiO 2 film is sandwiched between a TCO glass front electron collection electrode and a sputtered Ti back charge collection electrode, and a normal DSC (N-DSC), which has no back electrode. In N-DSCs, electrons in TiO 2 that are far from the front electrode have to diffuse for a long distance (ca. 10 μm), and therefore, the photocurrent cannot rapidly respond to light with a modulation frequency >100 Hz. In SW-DSCs, the photocurrent response was enhanced at frequencies between 10 and 500 Hz because electrons in TiO 2 can be extracted by both front and back electrodes, which can be also explained by an electron diffusion model. Calculations based on the electron diffusion model suggested that a high short-circuit photocurrent could be maintained in SW-DSCs even when the electron diffusion length in the TiO 2 film was shortened.

Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

Science.gov (United States)

Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

2014-12-01

Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

Photoelectrocatalytic property of microporous Pt-TiO2/Ti electrodes

International Nuclear Information System (INIS)

Hung, Chung-Hsuang; Wu, Kee-Rong; Yeh, Chung-Wei; Sun, Jui-Ching; Hsu, Chuan-Jen

2013-01-01

This study investigates the photoelectrocatalytic (PEC) property of microporous WO 3 -loaded TiO 2 /Ti layer, prepared via micro-arc oxidation (MAO) of Ti plate, followed by sputtering deposition of a thin Pt layer as a Pt-TiO 2 /Ti electrode. The WO 3 -loaded TiO 2 layer which is associated with a more acidic surface forms many local electrochemical cells on its micro-pores immersed in cationic dye solution. The electrocatalytic (EC) reactions can take place in the local cells by the applied electrons. A low resistivity that is accomplished by MAO technique and by platinization offers an easy path for the electron motions in the Pt-TiO 2 /Ti electrode. All these features make the EC oxidation of aqueous dye pollutants practically feasible without using counter electrodes and supporting electrolytes. Our experiments demonstrate that, under PEC condition, the Pt-TiO 2 /Ti shows the highest degradation rate constant of 0.83 h − 1 at an applied bias of 1.0 V and exhibits significantly high PEC and EC oxidation activities at a low applied bias of 0.25 V. This is attributable to high anodic currents generated in the Pt-TiO 2 /Ti even at low bias. The modified microporous electrodes conclusively reveal a very interesting EC property as a two double-sided device that functions the PEC and EC oxidation simultaneously without a need of supporting electrolyte and expensive Pt cathode. - Highlights: ► Pt-TiO 2 /Ti exhibits enhanced photoelectrocatalytic (PEC) activity at low applied bias. ► The proposed device uses low applied bias (< 1.0 V) with no explicit cathode. ► PEC oxidation can be performed without supporting electrolyte and Pt cathode

Corrosion behaviour of Al-Fe-Ti-V medium entropy alloy

Science.gov (United States)

Bodunrin, M. O.; Obadele, B. A.; Chown, L. H.; Olubambi, P. A.

2017-12-01

Alloys containing up to four multi-principal elements in equiatomic ratios are referred to as medium entropy alloys (MEA). These alloys have attracted the interest of many researchers due to the superior mechanical properties it offers over the traditional alloys. The design approach of MEA often results to simple solid solution with either body centered cubic; face centered cubic structures or both. As the consideration for introducing the alloys into several engineering application increases, there have been efforts to study the corrosion behaviour of these alloys. Previous reports have shown that some of these alloys are more susceptible to corrosion when compared with traditional alloys due to lack of protective passive film. In this research, we have developed AlFeTiV medium entropy alloys containing two elements (Ti and Al) that readily passivate when exposed to corrosive solutions. The alloys were produced in vacuum arc furnace purged with high purity argon. Open circuit potential and potentiodynamic polarisation tests were used to evaluate the corrosion behaviour of the as-cast AlFeTiV alloy in 3.5 wt% NaCl and 1 M H2SO4. The corrosion performance of the alloy was compared with Ti-6Al-4V alloy tested under similar conditions. The results show that unlike in Ti-6Al-4V alloy, the open circuit potential of the AlFeTiV alloy move towards the negative values in both 3.5 wt% NaCl and 1 M H2SO4 solutions indicating that self-activation occurred rapidly on immersion. Anodic polarisation of the alloys showed that AlFeTiV alloy exhibited a narrow range of passivity in both solutions. In addition, the alloys exhibited lower Ecorr and higher Icorr when compared with traditional Ti-6Al-4V alloy. The traditional Ti-6Al-4V alloy showed superior corrosion resistant to the AlFeTiV alloy in both 3.5 wt.% NaCl and 1 M H2SO4 solutions.

Electron densities and chemical bonding in TiC, TiN and TiO derived from energy band calculations

International Nuclear Information System (INIS)

Blaha, P.

1983-10-01

It was the aim of this paper to describe the chemical bonding of TiC, TiN and TiO by means of energy bands and electron densities. Using the respective potentials we have calculated the bandstructure of a finer k-grid with the linearized APW method to obtain accurate densities of states (DOS). These DOS wer partitioned into local partial contributions and the metal d DOS were further decomposed into tsub(2g) and esub(g) symmetry components in order to additionally characterize bonding. The electron densities corresponding to the occupied valence states are obtained from the LAPW calculations. They provide further insight into characteristic trends in the series from TiC to TiO: around the nonmetal site the density shows increasing localisation; around the metal site the deviation from spherical symmetry changes from esub(g) to tsub(2g). Electron density plots of characteristic band states allow to describe different types of bonding occurring in these systems. For TiC and TiN recent measurements of the electron densities exist for samples of TiCsub(0.94) and TiNsub(0.99), where defects cause static displacements of the Ti atoms. If this effect can be compensated by an atomic model one hopefully can extrapolate to stoichiometric composition. This procedure allows a comparison with structure factors derived from theoretical electron densities. The agreement for TiN is very good. For TiC the extrapolated data agree in terms of the deviations from spherical symmetry near the Ti site with the LAPW data, but the densities around both atoms are more localized than in theory. An explanation could be: a) the defects affect the electronic structure in TiCsub(0.94) with respect to TiCsub(1.0): b) the applied atomic model does not properly extrapolate to stoichiometry, because parameters of this model correlate or become unphysical. (Author)

Rapid Solidification of AB{sub 5} Hydrogen Storage Alloys

Energy Technology Data Exchange (ETDEWEB)

Gulbrandsen-Dahl, Sverre

2002-01-01

thesis the changes of the crystal structure and the grain structure of La{sub 0.60}Ce{sub 0.29}Pr{sub 0.04}Nd{sub 0.07}Ni{sub 3.37}Co{sub 0.79}Mn{sub 0.25}Al{sub 0.7}= cooling rate during chill-block melt spinning are described. Totally, the material was rapidly solidified at 9 different cooling rates. The grain structure, crystallographic texture and the lattice parameters were studied by means of electron microscopy and powder X-ray diffraction. Additionally, the density of the rapidly solidified materials was measured by a gas pycnometer. All these properties were found to change with increasing cooling rate. The grain size decreased continuously with increasing cooling rate and was in the range of 1-5 {mu}m. The strength of the crystallographic texture first increased and then decreased with increasing cooling rate. Transmission electron microscopy studies revealed that the grains contained a large amount of crystallographic twins and that the solidification morphology changed from cellular to plane front at a cooling rate during solidification of approximately 6*10{sup 4} Ks{sup -1}. The unit cell volume and the density followed the same pattern with increasing cooling rate and decreased within each solidification morphology, but at the cooling rate from which the morphology changed, both these parameters suddenly increased. The identical variations in the unit cell volume and the density is explained by formation of excess lattice vacancies during rapid solidification. In Part IV of the thesis rapid solidification of the materials La{sub 0.60}Ce{sub 0.27}Pr{sub 0.04}Nd{sub 0.09}Ni{sub 4.76}Sn{sub 0.24} and LaNi{sub 4.76}Sn different cooling rates are described. The materials were analysed by means of electron microscopy and powder X-ray diffraction. The grain structures of both alloys were found to be in the nanometer range, and the grain sizes were almost invariant with increasing cooling rate. Furthermore, the lattice parameters of these materials were almost

TEM characterization of a Cr/Ti/TiC graded interlayer for magnetron-sputtered TiC/a-C:H nanocomposite coatings

International Nuclear Information System (INIS)

Galvan, D.; Pei, Y.T.; De Hosson, J.Th.M.

2005-01-01

A TiC/a-C:H nanocomposite coating is deposited on top of a Cr/Ti/TiC graded interlayer. Cross-section transmission electron microscopy is employed to investigate the detailed structure of the interlayer and the coating. Five different phases are formed as a consequence of the compositional gradient within the interlayer: pure Cr, a solid solution of Ti in Cr, a Ti/Cr amorphous/nanocrystalline phase, α-Ti and TiC. Solid state amorphization occurs during the interlayer deposition to give a dispersion of TiCr β-phase nanocrystals in an amorphous matrix. The TiC phase is textured and contains numerous stacking faults as a result of the growth in under-stoichiometric carbon concentration. C-enriched columnar boundaries are present within the coating, originating from the TiC column boundaries of the interlayer. The work indicates that an interlayer of amorphous/nanocrystalline Ti/Cr phase would reduce the presence of growth defects such as columnar boundaries within nanocomposite TiC/a-C:H coatings

Characterization of consolidated rapidly solidified Cu-Nb ribbons