Amount Of Co Addition Research Articles

Co0.9Co0.1S Nanorods with an Internal Electric Field and Photothermal Effect Synergistically for Boosting Photocatalytic H2 Evolution.

The paper reports a strategy to synthesize Cd0.9Co0.1S nanorods (NRs) via a one-pot solvothermal method. Remarkably, the pencil-shaped Cd0.9Co0.1S NRs with a large aspect ratio and good polycrystalline plane structure significantly shorten the photogenerated carrier transfer path and achieve fast separation. An appropriate amount of Co addition enhances visible light-harvesting and generates a photothermal effect to improve the surface reaction kinetics and increases the charge transfer rate. Moreover, the internal electric field facilitates the separation and transfer of carriers and effectively impedes their recombination. As a result, the optimized Cd0.9Co0.1S NRs yield a remarkable H2 evolution rate of 8.009 mmol·g−1·h−1, which is approximately 7.2 times higher than that of pristine CdS. This work improves the photocatalytic hydrogen production rate by tuning and optimizing electronic structures through element addition and using the photothermal synergistic effect.

Thermomagnetic and structural analysis of as‐quenched Ni49Co1Mn37Sn13

AbstractIt is known that Co substitution in magnetic shape memory Ni‐Mn‐Sn alloys produces changes in their thermomagnetic behaviour. In this work, the Ni49Co1 Mn37Sn13 alloy was obtained by melt spinning in ribbon shape. The ribbon flakes were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), vibrating sample magnetometry (VSM) and differential scanning calorimetry (DSC). SEM micrographs indicate the formation of textured ribbons with columnar grains growing up perpendicular to the ribbons plane. The crystallographic structure of the sample at room temperature is the Heusler L21. DSC cyclic scans reveal the martensitic transformation on cooling and the reverse austenitic transformation on heating below room temperature. The application of a magnetic field produces a decrease in the transformation temperatures. The small amount of Co addition increases the Curie temperature of austenite. These facts suggest that the structural and magnetic phase transformation temperatures of the ribbons could be tuned to the desired functional temperature by controlling the applied magnetic field as well as the cobalt amount. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Microstructure and Mechanical Properties of Cu–Zr–Al Bulk Metallic Glass with Addition of Co

(Cu46Zr46Al8)100¹xCox (x = 0, 1, 2, 3 and 4) bulk metallic glasses (BMGs) were synthesized by copper mold casting, and the effect of Co addition on the microstructure and mechanical properties of Cu46Zr46Al8 BMG was investigated. The existence of immiscibility gap between Co and the main component Cu is responsible for liquid separation to form droplet-type structure during solidification. The size scale for the droplettype structure trends to increase with the Co concentration. Depending on the glass-forming ability of the separated liquid phase, amorphous/ amorphous or amorphous/crystalline composite structure can be obtained. The results of compression test reveal that the plasticity and the fracture strength can be simultaneously enhanced with an appropriate amount of Co addition owing to nanoscale phase separation with the formation of Cu-rich and Co-rich glassy phases. [doi:10.2320/matertrans.M2012375]

Magnetocaloric effect of Fe 64Mn 15− xCo xSi 10B 11 amorphous alloys

The magnetocaloric effect (MCE) of melt-spun Fe 64Mn 15− x Co x Si 10B 11 amorphous alloys with x = 0, 0.2, 0.5, 0.7, and 1.0 was evaluated with the aim of maximizing the magnetic entropy change close to the room temperature. The peak magnetic entropy change, Δ S M pk for Fe 64Mn 15Si 10B 11 at 309 K at H = 15 kOe was limited to 0.82 J/kg K. The magnetic properties and ensuing MCE were very sensitive to the Co content that it is conjectured that with a smaller amount of Co addition the Δ S M pk can be optimized while maintaining the Curie temperature near room temperature. It was also shown that the Fe 64Mn 15− x Co x Si 10B 11 amorphous alloys obeyed the master curve behavior as the magnetic entropy change curve collapsed on to a single universal curve.

Effects of Processing and Amount of Co Addition on Shear Strength and Microstructual Development in the Sn-3.0Ag-0.5Cu Solder Joint

Due to its high Young’s modulus and strong bond with Sn, Co has been considered as one of the most promising alloying elements to improve the strength and reliability performance of Pb-free solders. In this study, the microstructual characteristics and mechanical properties of Sn-3.0Ag-0.5Cu + XCo (X = 0 wt.%, 0.1 wt.%, 0.2 wt.%, 0.45 wt.%, and 1.0 wt.%) solder joints on Cu substrates were investigated. Moreover, an exploration on different joint fabrication methods and undercooling of solder alloys with both solder preform and paste was carried out. Experimental results indicated that the undercooling of the solder alloy can be altered by Co additions. During the metallurgical process, the added Co can dissolve into the solder matrix before rolling the preform. In addition, Co can form reinforcement particles in the solder paste. The tendency for the formation and growth of an intermetallic compound (IMC) layer can be enhanced after incorporation of Co elements into the preform. However, a proper amount of Co addition to the paste can suppress IMC growth. The shear strength of solder joints reinforced with 0.1 wt.% or 0.2 wt.% Co addition can be increased. The solder joint made by paste with 0.2 wt.% Co addition exhibited the highest shear strength among all the solder joints.

Magnetic properties of phase separated glasses and glass ceramics in Co3O4-TiO2-SiO2 system

The phase separated glass ceramics in Co3O4-TiO2-SiO2 ternary system were prepared by a melt-quenching method and their magnetic properties were investigated. The samples in the xCoO-(48.5 – 0.5x)TiO2-(48.5 – 0.5x)SiO2-3.0Al2O3 (x = 3, 5, 10) consisted of TiO2-rich particles and a SiO2-rich matrix and this phase-separated structure was formed by a nucleation-growth process. This phase-separated glass ceramics showed the magnetic hysteresis loop due to a mixture of ferromagnetic and paramagnetic phases. From the X-ray diffraction measurements, it was confirmed that the samples had the TiO2 rutile phase and amorphous phase without the other crystalline phases. The magnetic susceptibility increased and the coercive force decreased with increasing the amount of Co addition. These results indicated that the prepared samples had the ferromagnetic Co-doped TiO2 rutile phase and the paramagnetic amorphous phase which contains Co divalent ions.

Physicochemical properties and electrochemical behavior of binary manganese–cobalt oxide electrodes for supercapacitor applications

Binary Mn–Co oxide electrodes were prepared by anodic deposition at 25 °C in a mixture of manganese acetate and cobalt acetate aqueous solutions. It was found that the Mn-to-Co content ratio in the oxide could be easily controlled by adjusting the composition of the plating solution. The chemical states of the oxides produced were analyzed using an X-ray photoelectron spectroscope, and the deposition mechanism was thus explored in this study. Chronopotentiometry was also performed to evaluate the pseudocapacitive characteristics of the oxide electrodes. The experimental results indicated that an appropriate amount of Co addition could effectively inhibit the anodic dissolution of Mn and consequently improve the electrochemical reversibility and stability of the oxide electrode. However, it was also confirmed that high Co content caused a significant reduction in the specific capacitance of the oxide.

소량의 첨가원소가 Strip-Cast Nd-Fe-B 향금의 미세 조직 형성에 미치는 영향

고에너지 Nd-Fe-B소결자석 제조용 strip-cast합금의 미세조직을 개선하기 위하여, Nd<TEX>$_{14}$</TEX>Fe<TEX>$_{80}$</TEX>B<TEX>$_{6}$</TEX>6의 기본 조성에 소량의 Cu (0.3 ～ 1.0 at%) Co (0.5 ～ 1.5 at%)를 각각 첨가하고 strip-casting법으로 합금을 제조한 후, 이들 Fe 치환원소의 첨가량 변화가 합금의 상형성, 상분포 및 조직 형성에 미치는 영향을 조사하였다. Cu첨가량이 증가함에 따라 용탕의 유동성이 증가하여 strip 두께가 감소함과 함께 strip표면에 수직한 방향으로의 수지상정 발달이 억제되었으나, Co첨가량이 증가한 경우에는 strip두께의 증가와 함께 strip표면에 수직한 방향으로 수지상정이 잘 발달하여 <001>방향으로의 preferred orientation이 증가하는 경향을 보였다. 이들 Cu와 Co의 첨가는 모두 수지상정을 미세화하는 효과가 있었으나, Cu는 Fe의 정출을 안정화시키는 경향이 있어서 Cu가 함유된 함금에서는 종종 Fe가 종종 정출한 반면, Co는 초정 Fe의 정출을 억제하는 효과가 있었다. 한편, 소량의 Zr (0.3, 0.5 at%)을 첨가하였을 때에는 전체적인 결정립의 조대화와 함께 수지상정의 붕괴를 초래하였다. In order to improve dendritic formation of Nd<TEX>$_2$</TEX>Fe<TEX>$\_$</TEX>14/B phase in the strip-cast Nd-Fe-B alloys that are frequently used for production of high energy sintered magnets, effect of small substitutional additives such as Cu (0.3～1.0 at. %) and Co (0.5～1.5 at.%) on the phase formation and microstructures of the strip-cast alloys based on Nd<TEX>$\_$</TEX>14/Fe<TEX>$\_$</TEX>80/B<TEX>$\_$</TEX>6/ were investigated. As the amount of Cu addition increased, formation of Nd<TEX>$_2$</TEX>Fe<TEX>$\_$</TEX>14/B dendrites along the direction normal to the strip surface was suppressed with the reduction of the strip thickness mainly due to the increase of fluidity of the melt. However, both the dendrites and their <001> preferred orientation along the direction normal to the strip surface were improved with the increase of the strip thickness as the amount of Co addition increased. The dendrites became finer after small amount of Cu or Co was added. While small copper additions tended to stabilize the formation of primary Fe, small cobalt additions suppressed it. When small amount of Zr was added, however, the dendrite structures were totally collapsed with excessive grain growth of Nd<TEX>$_2$</TEX>Fe<TEX>$\_$</TEX>14/B.

Investigation on the characteristics of La 0.7Mg 0.3Ni 2.65Mn 0.1Co 0.75+ x ( x = 0.00–0.85) metal hydride electrode alloys for Ni/MH batteries Part II: Electrochemical performances

In this paper, the electrochemical performances of the La 0.7Mg 0.3Ni 2.65Mn 0.1Co 0.75+ x ( x = 0.00–0.85) alloy electrodes were studied. The results show that, with increasing amount of Co addition, the maximum discharge capacities of the alloys decrease monotonously due to the relative change of the phase abundance of the (La, Mg)Ni 3 phase and the LaNi 5 phase coexisting in the alloys and the increase of the equilibrium pressure for hydrogen desorption. Moreover, the cycling stability of the alloy electrodes was noticeably improved with increasing Co addition because of the relatively lower value of V H and the formation of protective oxides (hydroxides). The high rate dischargeability of the alloy electrodes increases first and then decreases with increasing amount of Co addition, and the alloy electrode with x = 0.30 exhibits the best electrochemical kinetics. In addition, the electrochemical kinetic parameters study, including the charge-transfer resistance at the surface R ct, the polarization resistance R p, the exchange current density I 0, the limiting current density I L and the diffusion coefficient of hydrogen in the alloys D, also confirm this result.

Ｗ‐Ｎｉ‐Ｆｅ系焼結合金の機械的性質に及ぼすＣｏ添加の影響

This report describes the results of investigations on the improvement of characteristics of tungsten heavy alloys which were produced with addition of suitable amount of Co (with Ni/Fe ratio of about 2.0) to basic composition of W-Ni-Fe, and an optimum amount of Co addition obtained. The mechanical properties at room temperature of the (91.8-93.4 wt% W) alloys increased with increasing Co content and attained a maximum with Co content of about 1.5 wt%, while the 95.4 wt% W alloys attained a maximum with Co content of about 0.5 wt%.In the alloys with (addition of) suitable amount of Co, smaller dihedral angle between W-W grain and better Wettability were obtained, and it was made clear that those effect resulted in homogeneity of alloys, and the improved mechanical properties.The SEM photographs of the fracture surfaces show that Co content alloys strengthen mainly the interface between W-binder phase boundaries and W-W grain boundaries.