Fishbone Structure Research Articles

Lattice relations and solidification of the complex regular eutectic (Cr,Fe)-(Cr,Fe)23C6

The eutectic (Cr,Fe)-(Cr,Fe)23C6 showed a triaxial fishbone structure and could be categorized as a “complex regular structure”. In this study, the lattice relations of the fishbone (Cr,Fe)23C6 were examined and the solidification process was observed using a transmission electron microscope and a confocal laser scanning microscope. For one of the three fish bones in a eutectic cell, parallel (Cr,Fe)23C6 lamellas at one side of the spine had the same lattice direction, as did those in the (Cr,Fe) phase. The lattices of neighboring (Cr,Fe)23C6 and (Cr,Fe) phases were not coherent. Lamellar (Cr,Fe)23C6 on opposite sides of a spine had different lattice directions, and their lattice boundary was in the spine. By using the confocal laser scanning microscope, the solidification of lamellar eutectic structure could be observed. At the low cooling rate of 5 o C·min-1, parallel lamellas would grow thick blocks instead of thin plates. To obtain a thin lamellar eutectic structure, the cooling rate should be higher, like the rate in welding.

Formation of self-assembled micro- and nano-domain structures in uniaxial ferroelectrics

We present the experimental study of appearance of domain wall shape instabilities and self-assembled domain structures in uniaxial ferroelectrics lithium niobate and lithium tantalate covered by artificial dielectric layer. The domain structure evolution has been considered as a manifestation of nucleation processes similar to the first order phase transformation. The necessary conditions for formation of self-assembled domain structures including the highly non-equilibrium switching conditions and stability of concave angles were proposed. The formation of the self-assembled domain shape instabilities under application of the uniform external electric field during switching (domain growth) and backswitching (domain shrinkage) has been studied experimentally with these conditions fulfilled. The formation of the bumps at the vortexes of hexagon domain for diameter above 3 - 5 μm with subsequent oriented growth was obtained in stoichiometric lithium tantalate. The formation of quasi-regular fish-bone domain structure has been revealed during spontaneous backswitching in Mg doped lithium niobate. The resulted structure consisted of the narrow residual domains with width from 200 to 500 nm appeared as a result of finger growth to the center of hexagon domain. The obtained decreasing of the number of the residual domains during growth has been attributed to strong electrostatic interaction of domain walls.

A microfluidic system that specifically screens bladder cancer cells from circulating tumor cells

Objective To fabricate a microfluidic chip to specifically screen bladder cancer cells. Methods Using microfluidic technology, we designed and fabricated filter chips that can specifically isolate circulating bladder cancer cells from May 2015 to April 2016. The chip was fabricated through photolithography after spin coating negative photoresist, trimming, punching and cleaning process. The surface of the microchannel was modified by biotin-avidin-BCMab1-system (BAS). The blood sample containing T24 cells was used to test the validly of the chip. Results Chip was consisted of two layers, whose size was 4.0 cm × 0.3 cm ×0.5 cm. The upper structure was the fishbone structure that changed the fluid flow state. The fishbone structure was 45μm high and the spacing between fishbone structure was 50μm. The lower structure that captures the circulating tumor cells was micro-channel whose height was 50 μm. The whole chip modified by bladder cancer monoclonal antibody-BCMab1 could capture bladder cancer circulating tumor cells with high specificity, and capture rate was as high as 90%. Conclusions In summary, this chip might be a new way to diagnosis bladder cancer. Key words: Bladder cancer; Circulating tumor cells; Specific screening; Microfluidic device

Characteristics of Eutectic α(Cr,Fe)-(Cr,Fe)23C6 in the Eutectic Fe-Cr-C Hardfacing Alloy

A specific eutectic (Cr,Fe)-(Cr,Fe)23C6 structure had been previously reported in the research studies of Fe-Cr-C hardfacing alloys. In this study, a close observation and discussion of the eutectic (Cr,Fe)-(Cr,Fe)23C6 were conducted. The eutectic solidification occurred when the chromium content of the alloy exceeded 35 wt pct. The eutectic structure showed a triaxial radial fishbone structure which was the so called “complex regular structure.” Lamellar costa plates showed local asymmetry at two sides of a spine. Individual costae were able to combine as one, and spines showed extra branches. Costae that were nearly parallel to the heat flow direction were longer than those that were vertical to the heat flow direction. The triaxial spines preferred to intersect at 120 deg, while the costae preferred to intersect the spine at 90 deg and 35.26 deg due to the lattice relationships. The solidified metal near the fusion boundary showed an irregular structure instead of a complex regular structure. The reason for the irregular morphology was the high growth rate near the fusion boundary.

High-efficiency polarization conversion based on spatial dispersion modulation of spoof surface plasmon polaritons.

In this paper, we propose to achieve high-efficiency polarization conversion based on spatial dispersion modulation of spoof surface plasmon polaritons (SSPP). Different k is firstly designed in the two transverse directions by aligning an SSPP-supporting fishbone structure in y direction while maintaining free space in x direction. The orthogonal phase difference is introduced by larger k of SSPP waves for y-polarized component of incident waves. Meanwhile, to achieve high efficiency, gradient k in z-direction is designed so that the y-polarized component of incident waves can be coupled perfectly as SSPP waves. By rotating the fishbone structure with respect to the polarization direction of incident waves, different polarization states for transmitted waves can be realized. As an example, a polarization converter prototype with the central working frequency f = 8GHz was designed, fabricated, and measured. Both the simulation and experiment demonstrate the high-efficiency linear-to-circular (LTC) polarization conversion in 6.9-9.6GHz.

Nitrogen-Doped Carbon Nanofibers for the Oxygen Reduction: The Role of Iron As Growth Catalyst

Nitrogen-doped carbon nanofibers (N-CNFs) prepared in the presence of Fe have shown promising activity for the oxygen reduction reaction (ORR), the cathode reaction in fuel cells 1–3. However, in acidic electrolyte the ORR-activities reported so far has not been as high as for Pt/C. This could be due to low active site density and poor accessibility of the active sites to the oxygen molecules. In addition, the nature of the active sites and the role of the transition metal used as carbon growth catalyst still remain unclear. Here, a systematic evaluation of the ORR on N-CNFs has been performed by tailoring the physicochemical properties of the N-CNFs using a catalytic chemical vapor deposition method. The role of iron has been further explored by post-treatment of the N-CNFs with nitric acid combined with careful analysis using XPS, EELS and XAS. The N-CNFs were prepared by decomposing CO and NH3 over 20 wt% Fe supported on expanded graphite. By varying the synthesis conditions such as synthesis temperature and NH3-partial pressure the N-content, N-groups and microstructure of the N-CNFs could be tailored. Characterization of the elemental composition and N-groups present at the surface of the N-CNFs was done by XPS. The N-CNFs grown at 650⁰C were treated with concentrated nitric acid and annealed at 900⁰C in order to remove metallic Fe and oxygen functional groups respectively. The remaining iron was then characterized by EELS, and in-situ under reducing conditions using EXAFS/XANES. The electrocatalytic activity for the oxygen reduction was examined by performing linear sweep voltammetry in 0.5M H2SO4. Detection of H2O2formed during the ORR was enabled using a rotating ring disk electrode. By increasing the CVD synthesis temperature from 650⁰C to 750⁰C the N-CNF yield increased while the N-content in the surface of the N-CNFs decreased from 4.8at% to 1.4at% respectively, see Fig. 1a. Furthermore, at 750⁰C the N-CNFs contained more quaternary nitrogen, while synthesis at lower temperatures favored the presence of pyridinic nitrogen groups. This could be related to the microstructure of the N-CNFs since the N-CNFs grown at lower temperatures showed a fishbone structure, while the N-CNFs grown at 750⁰C were similar to multiwalled CNTs and thus contained fewer edges. Furthermore, increasing the partial pressure of NH3resulted in N-CNFs with higher N-content and a higher percentage of pyridinic nitrogen incorporated in the N-CNFs. Testing of the N-CNFs for the oxygen reduction in acidic electrolyte, Fig. 1a, revealed that the N-CNFs with the highest nitrogen content were the most active oxygen reduction catalysts. Harsh post treatment with nitric acid was used to remove Fe from the N-CNFs. TEM imaging after acid treatment and annealing, Fig. 1b, showed clean N-CNFs with no visible iron particles. However, EELS analysis (Fig. 1c-e) revealed a weak, but consistent and homogeneous Fe signal in the N-CNFs. In addition, the activity and selectivity for the oxygen reduction was preserved after acid treatmet. Further analysis with XAS showed that the iron remaining in the N-CNFs was not iron oxide or metallic iron, but rather iron coordinated to nitrogen or carbon. In conclusion, the optimal CVD synthesis temperature for achieving an active ORR-catalyst based on N-CNFs was 650⁰C. Furthermore, a high NH3 partial pressure gave high nitrogen content in the surface of the N-CNFs and was beneficial for both the oxygen reduction activity and the selectivity towards H2O. The best N-CNFs catalyst contained 5.8 at% nitrogen and showed an ORR onset potential of 0.96V vs. RHE. Characterization of the post-treated N-CNFs with EELS and XAS showed that iron was incorporated into the N-CNF structure during synthesis. This suggests that Fe-Nxmoieties can be formed during N-CNF growth from Fe and could be the active sites for the ORR on N-CNFs. 1. M. E. M. Buan, N. Muthuswamy, J. C. Walmsley, D. Chen and M. Rønning, Carbon 101 (2016) 191–202. 2. Y. Li, W. Zhou, H. Wang, L. Xie, Y. Liang, F. Wei, J.-C. Idrobo, S. J. Pennycook and H. Dai, Nat. Nanotechnol. 7 (2012) 394–400. 3. D. Singh, J. Tian, K. Mamtani, J. King, J. T. Miller and U. S. Ozkan, J. Catal. 317 (2014) 30–43. Figure 1

Surface reconstruction: An effective method for the growth of mismatched materials

The crystalline quality of epitaxial films depends on the degree of lattice match between substrates and films. Here, we report a growth strategy for large mismatched epi-films to grow GaSb films on Si(111) substrates. The epitaxial strategy can be influenced by controlling the surface reconstructions of Sb-treated Si(111). The film with the best quality was grown on Si(111)-(5⿿3ÿ5⿿3)-Sb surface due to the stress release and the formation of a self-assembled 2D fishbone structure. Controlled surface engineering provides an effective pathway towards the growth of the large mismatched materials.

Three Metal(II) Diphosphonates with d 10 Electron Configuration: Structural, Fluorescent and Electrochemical Studies

By introducing the second ligand 1,10-phenanthroline (phen), three low-dimensional examples of CdII/ZnII diphosphonates based on 1-hydroxyethylidenediphosphonic acid (H5L = CH3C(OH)(PO3H2)2), [Cd2(H3L)2(phen)2(H2O)2] 1, {[Zn3(H2L)2(phen)2]·2H2O}n 2 and [Zn2(H3L)2(phen)2]·(HOCH2CH2OH) 3, have been hydro- or solvo-thermally obtained and characterized by powder X-ray diffraction (PXRD), elemental analysis, IR, TG-SDTA. The single-crystal X-ray diffractions show that both compounds 1 and 3 display zero-dimensional structures built from binuclear units [M2(OPO)2] n (M = CdII/ZnII) via a double O–P–O bridge, and compound 2 possesses one-dimensional fish-bone inorganic chain structure with three types of coordination modes of Zn(II) ions. Then H-bond or/and π–π stacking interactions further expand the low-dimensional structures into the three-dimensional supramolecular frameworks. Fluorescent measurements reveal that the maximum emission peaks (371.5, 391.5 nm for 2 and 376.5, 392.5 nm for 3) of 2–3 have a significant increase in intensity compared to those of the phen ligand (λ em = 362.5, 379 nm, λ ex = 335 nm), which are mainly caused by intraligand π*–π emission state of the phen ligand. The results of electrochemical measurements indicate the donor ability of 1–3 has gone up, compared with the ligands (H5L and phen). Three examples of CdII/ZnII diphosphonates have been hydro- or solvo-thermally obtained. Two Zn(II) diphosphonates with 1,10-phenanthroline indicate a significant increase in intensity of fluorescence. The results of electrochemical measurements indicate the donor ability of CdII/ZnII diphosphonates increase, compared with the ligands H5L and phen.

Manajemen Risiko Pada Bandara Soekarno Hatta Berbasis ISO 31000

Soekarna Hatta Airport as an international aviation company hasn’t yet implemented an international standard risk management system based on ISO 31000, so it triggers the occurrence of negative impacts to the human, environment, property and company reputation. This research aims to conduct a risk assessment and control by using an international standard risk management system. Risk management research is focused on the negative impacts caused by an event of airport operations, particularly operations facility and machine. The Stages of the risk management process are based on ISO 31000 including risk identification, risk analysis, and risk evaluation using fishbone and Risk Breakdown Structure (RBS) tool. Impact Expectations and possible occurrence are mapped through the risk matrix which is defined by the Federation Aviation Administration (FAA). The results showed that there were7 events at Soekarno Hatta airport that have potential risk, namely, outbreak of the runway track, plane accidence during take-off/landing, disruption of flight navigation and communication services, accidence in the apron area, security disruption at the airport, aircraft jetblast, and entry of dangerous goods on board.

Characterization of sliders for efficient force generation of electrostatically controlled linear actuator

In this paper, the characterization of sliders for efficient force generation of an electrostatically controlled linear actuator (ECLIA) is investigated. The ECLIA consists of a piezoactuator (PZT), driving and holding electrodes, multiple sliders and a guide structure. The stepping motion of the sliders is driven by the PZT actuator via an electrostatic clutch mechanism. Thus, multiple sliders can achieve parallel, independent, precise motion, and a large stroke. Previous studies have indicated that the Si bulk slider and Si electrode created an air gap owing to the deformation of the Si electrode. Thus, the Si slider generated a low pushing force. In this study, we propose a fishbone structure mounted on a flexible slider to enhance the pushing force of the slider. The flexible slider, that can deform and fit into the Si electrode to reduce the air gap, results in highly efficient electrostatic-force generation. The fishbone structure improves the longitudinal stiffness of the flexible slider for high pushing-force generation. The results show that the pushing force created by the fishbone slider was three times greater than that of the conventional Si slider. The fishbone and flexible sliders exhibited a high performance for the ECLIA.

Fish bone structure based data aggregation and routing in wireless sensor network: multi-agent based approach

Wireless sensor networks (WSNs) are constrained by limited node (device) energy, low network bandwidth, high communication overhead and latency. Data aggregation alleviates the constraints of WSN. In this paper, we propose a multi-agent based homogeneous temporal data aggregation and routing scheme based on fish bone structure of WSN nodes by employing a set of static and mobile agents. The primary components of fishbone structure are backbone and ribs connected to both sides of a backbone. A backbone connects a sink node and one of the sensor nodes on the boundary of WSN through intermediate sensor nodes. Our aggregation scheme operates in the following steps. (1) Backbone creation and identifying master centers (or nodes) on it by using a mobile agent based on parameters such as Euclidean distance, residual energy, backbone angle and connectivity. (2) Selection of local centers (or nodes) along the rib of a backbone connecting a master center by using a mobile agent. (3) Local aggregation process at local centers by considering nodes along and besides the rib, and delivering to a connected master center. (4) Master aggregation process along the backbone from boundary sensor node to the sink node by using a mobile agent generated by a boundary sensor node. The mobile agent aggregates data at visited master centers and delivers to the sink node. (5) Maintenance of fish bone structure of WSN nodes. The performance of the scheme is simulated in various WSN scenarios to evaluate the effectiveness of the approach by analyzing the performance parameters such as master center selection time, local center selection time, aggregation time, aggregation ratio, number of local and master centers involved in the aggregation process, number of isolated nodes, network lifetime and aggregation energy. We observed that our scheme outperforms zonal based aggregation scheme.

Structure and Texture Formation During Single and Double Cold Rolling and Annealing Processes for Nb+Ti Added Interstitial-Free Steels

The structure and texture formation for single cold rolling (SCR) with annealing and double cold rolling (DCR) with annealing were investigated based on optical microscope and X-ray diffraction (XRD) with a Nb + Ti bearing interstitial free (IF) steel. The results indicated that DCR recrystallization grain was smaller than that of SCR sample and double cold rolling process resulted in better mechanical properties than those resulted from single cold rolling process with the same total reduction conducted. The plastic strain ratio increases from 2. 23 for single cold rolling process to 3. 2 for double rolling process. The fish-bone structure was observed in all SCR and DCR samples. DCR annealed sample is made up of equiaxed grains of almost uniform size, whereas SCR annealed sample shows a duplex grain structure, consisting of both large and small-sized grains. (Ti+Nb) C and Fe(Ti+Nb) P type precipitates were very rarely observed in SCR annealed and DCR annealed steels. The intensity of {111} // ND for the DCR annealing was higher than that for SCR annealing.

Phase and microstructure of TbCu7-type SmFe melt-spun powders

The SmxZr0.3Fe9.1–xCo0.6 (x=0.8, 0.9, 1.0) powders were prepared by melt-spun method with different quenching velocities. The phase and microstructure were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Th2Zn17-type structure of the as-cast state changed to TbCu7-type after quenching to a rotating molybdenum roll under certain velocity, and the formation of TbCu7-type phase was strictly depending on the Sm content and roll speed. The SEM morphology showed that the Fe-rich zone was typically fish-bone structure and TEM diffraction pattern indicated the nano-scale crystal size with TbCu7-structure when x=0.9, and FCC type γ-Fe on the basis of α-Fe formed in the non-equilibrium solidification could be detected by selected area electron diffraction (SAED) indexing in the x=0.8 samples.

Evolution of acoustic cavitation structures induced by a liquid jet

Temporal evolution and spatial distribution of acoustic cavitation structures induced by a liquid jet in a 20 kHz ultrasonic field were investigated experimentally with high-speed photography. It is revealed that a large-scale flare structure is produced by a liquid jet shooting towards a transducer radiating surface. A few large bubbles and numerous small bubbles are formed on the interface of liquid jet. The size of large bubbles differs almost by an order of magnitude from that of small bubbles. The flare structure hits the radiating surface, spread and adhere. The liquid jet is arrested and a thin bubbly layer lying at the radiating surface is formed. The cavitation cloud will evolve from one structure to another without the interference of liquid jet. (a) Most bubbles move towards the center, and the bubbly layer will become thicker at the centre than at the periphery like a lens. (b) Large bubbles accumulate at the center and skip off the surface, and the lens structure becomes a conical structure. (c) Large bubbles align themselves along the axial line, and the conical structure becomes a fishbone structure. Many other interesting phenomena were observed. The liquid-jet method is useful for the investigation of cavitation structure. This work is supported by the National Natural Science Foundation of China (Grant No. 11174315) and the National Science and Technology Major Project of China (Grant No. 2011ZX05032-003).

Effects of Sc content on the microstructure of As-Cast Al-7wt.% Si alloys

The effects of Sc content on the microstructure of as-cast Al-Si alloys were investigated by adding 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, and 0.4 wt.% Sc to hypoeutectic Al-7 wt.% Si alloys. The results show that there are significant changes in the microstructure when the Sc content is increased to 0.15%. The volume fraction of the primary α-Al phase increased nearly monotonically with increasing Sc content in the as-cast state. As the Sc content increased, the average length of the eutectic Si in the as-cast Al-7Si-xSc alloy decreased sharply from 150 μm (without Sc content) to 20 μm (0.4 wt.% Sc content). The Sc atoms are concentrated in the interdendritic regions. A fish-bone structure composed of Al, Si, Sc, and Fe, which might be the Fe-rich phase precipitated on the AlSc 2 Si 2 (V-phase) was detected adjacent to the grain boundary by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). ► Significant changes in the microstructure when the Sc content is increased to 0.15%. ► Volume fraction of the primary a-Al phase increased with increasing Sc content. ► Average length of Si decreased sharply from 150 to 20 μm with increasing Sc content. ► The Sc atoms are concentrated in the interdendritic regions.

Preparation Technology of the Low Carbon High Boron Fe-C-B Wear Resistance Steel

The solidified microstructure and the modified treatment have been systematic studied for the low carbon high boron Fe-C-B steel. The cast solidified microstructures of the low carbon high boron steel are consisted of the matrix and the boride phases. The matrix phase is consisted of the ferrite, pearlite and a few martensite phases. The boride phases of the hypoeutectic steel are based mainly on the Fe2B phase. With the increasing of the boron content, the Fe2B phase is decreased. When the boron content is excess 2.6wt.%, the boride phases are changed from the single Fe2B phase to the compound structures. Meanwell, the morphologies of the boride phases are transformed from the long strip-shaped and the fish-bone reticular structure to the rosette type. The boride phases of the eutectic steel are mainly the M2B phase. However, for the hypereutectic steel, it are composed of the M23(C, B)6 and B0.7Fe3C0.3 phases. The suitable modifier for the hypoeutectic low carbon high boron steel is the compound modifier 0.2%RE+0.2%Ti. After modified, the reticular boride phases are disconnected. Moreover, there existed some of isolated massive borides. The appropriate modifier for the hypereutectic steel is the compound modifier 0.9%Nb+0.4%RE. After modified, the primary borides are fine refined and tend to round.

Effect of ammonia gas etching on growth of vertically aligned carbon nanotubes/nanofibers

The etching effect of ammonia (NH 3) on the growth of vertically aligned nanotubes/nanofibers (CNTs) was investigated by direct-current plasma enhanced chemical vapor deposition (DC-PECVD). NH 3 gas etches Ni catalyst layer to form nanoscale islands while NH 3 plasma etches the deposited amorphous carbon. Based on the etching effect of NH 3 gas on Ni catalyst, the differences of growing bundles of CNTs and single strand CNTs were discussed; specifically, the amount of optimal NH 3 gas etching is different between bundles of CNTs and single strand CNTs. In contrast to the CNT carpet growth, the single strand CNT growth requires shorter etching time (5 min) than large catalytic patterns (10 min) since nano dots already form catalyst islands for CNT growth. Through removing the plasma pretreatment process, the damage from being exposed at high temperature substrate occurring during the plasma generation time is minimized. High resolution transmission electron microscopy (HTEM) shows fishbone structure of CNTs grown by PECVD.

Synthesis of MWCNTs and hydrogen from ethanol catalytic decomposition over a Ni/La 2O 3 catalyst produced by the reduction of LaNiO 3

In the present paper we present a clean process that allows the simultaneous production of hydrogen and carbon nanotubes based on catalytic decomposition of ethanol, which is a renewable energy source. The catalyst consists of Ni nanoparticles highly dispersed on La 2O 3, obtained by the reduction of LaNiO 3. The effect of reaction conditions, such as reaction temperature and ethanol heating temperature, on the gaseous composition of the produced gas and the characteristics of the carbonaceous deposits was studied. An increase of the reaction temperature leads to an increase in H 2 production. The carbonaceous deposits were characterized by TGA, Raman spectroscopy TEM and HRTEM analysis. TEM micrographs show that the nanotubes were multi-walled with inner diameters ranging from 4 nm to 12 nm and outer diameters up to 75 nm. At low reaction temperatures the production of fibers is favored. The best graphitized carbon material was obtained when ethanol reacts at the surface of the catalyst instead of products issued from the thermal decomposition of ethanol (CH 4, CO, CO 2, C 2H 6 and C 2H 4). The yield of carbon nanotube (CNT) and H 2 were 3.5 g CNT (g cat h) −1 and 39 L H 2 ( g h ) − 1 respectively at 700 °C. The inner diameter of the CNTs does not depend on the experimental conditions used, whereas the outer diameter strongly depends on the reaction temperature (from 500 °C to 700 °C). From HRTEM images two types of carbon materials were shown: one with parallel graphene layers and one with fishbone structure. The intershell spacings d ˆ 0 0 2 were measured, the average value was equal to 0.344 nm for parallel tubes, while in curvature the d spacing is higher: 0.360 nm.

Effect of chromium concentration on microstructure and properties of Fe–3.5B alloy

The cast low carbon Fe–3.5B alloys containing various chromium concentrations were prepared in a 10 kg medium frequency induction furnace and the effects of chromium concentration on microstructure and properties of Fe–3.5B alloys have been examined by means of optical microscope (OM), scanning electron microscope (SEM), back-scattered electron microscope (BSE), electron probe microanalyzer (EPMA), energy dispersive spectrum (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Vickers hardness. As a result, the as-cast structures of Fe–3.5B– XCr ( X = 0, 2, 5, 8, 12, 18, mass fraction) alloys are mainly composed of dendrite ferrite, martensite, pearlite and boride. The boride in the alloy without chromium addition comprises the eutectic Fe 2B, which is continuous netlike or fish-bone structure distributed over the metallic matrix. With the increase of chromium concentration in Fe–3.5B alloy, matrix structure turns into the supersaturated α-Fe solid solution while the morphology of boride becomes dispersed due to the transformation of boride from simple Fe 2B to (Fe,Cr) 2B when the chromium concentration in Fe–3.5B alloy exceeds 8 wt.%. Meanwhile, some primary M 2B-type borides may precipitate under this condition. The bulk hardness of the as-cast alloy ranges from 41.8 to 46.8 HRC. However, the bulk hardness of the heat treated alloy rises first and falls later mainly because of the morphology variation of structure. Fracture toughness of boride is improved gradually owing to the entrance of chromium into Fe 2B, which may be attributed to the change of spatial structure of boride.

Atomization patterns produced by the oblique collision of two Newtonian liquid jets

This paper reports a detailed experimental investigation of the formation, destabilization, and atomization of the liquid sheets created by the oblique impact of two laminar jets of a Newtonian liquid. Glycerol-water mixtures with viscosities between 4 and 30 mPa s were used to investigate the effects of viscosity and jet velocity. The jets were ejected from parallel cylindrical nozzles with an internal diameter of 0.85 mm. Collision of the jets resulted in various regimes of behavior which depend on the jet velocities and the liquid properties. We focus on the regime where the impinging jets form a liquid sheet which then breaks up into a regular succession of ligaments and droplets, a so-called “fishbone” pattern. We use short-duration, single-flash illumination combined with high-resolution digital photography to study the evolution of the sheet, its shape, and the form, size, and spacing of resulting ligaments and drops. Unexpectedly, we found fishbone regimes corresponding to lower Reynolds and Weber numbers than had been previously reported; furthermore our apparently symmetric fishbone structures were definitely associated with asymmetric, rather than symmetric, impacting jet conditions. The fishbone structure was found to be significantly affected by any asymmetry in either the free lengths of the two jets or their alignment. The fishbone angle, defined as the angle between the lines through the first pairs of droplets on each side of the fishbone structure, is introduced to describe the effects of differences in jet length, alignment, or fluid properties on the degree of development of the fishbone pattern. We discuss how changes in the various parameters influence the form of the fishbone pattern and the origin and mechanism of the periodic atomization of the sheet. In particular we find that the dependence of the drop spacing on viscosities is consistent with the Rayleigh–Plateau instability on the rim provided the variation of the rim width is properly included, as this dominates the Ohnesorge number dependence of the breakup.