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Nd:YAG pulsed laser lap-welding of Hastelloy C-276 and 304 stainless steel was conducted. The effect of pulse energy on weld morphology, element distribution, microstructure, phase structure, tensile-shear property and corrosion property of weld joint was analyzed. The results indicated that, with the increase of pulse energy, both the penetration depth and bead width of weld metal (WM) and dilution level of 304 base metal (BM) were linearly increased. Unmixed zone between WM and 304 BM was reduced, however, the grains sizes in WM became coarser. The precipitated phase with higher content of Mo and W is mainly p phase, with the increase of pulse energy, segregation potential of Mo element was increased, however, the amount of precipitated phase was decreased due to a decline in Mo element in WM. The fracture mode of weld joint transferred from interfacial fracture to tensile fracture with the increase of bead width, and the maximum load capacity of which was achieved at a pulse energy of 4.0 J. The average micro-hardness value of WM was decreased with the increase of pulse energy due to the depletion of Mo and W strengthening elements and the coarser grain size in WM. The corrosion resistance of WM was weakened with the increase of pulse energy ascribed to the reduce of Ni and Mo elements.

The Ba2P2O7:Tb3+, Eu3+ phosphors were synthesized by a high temperature solid-state reaction method in air atmosphere and their crystal structures, lifetime, luminescence properties, and energy transfer mechanism were investigated in detail. A series of characteristic emissions of Ba2P2O7:Tb3+, Eu3+ phosphors were observed in the emission spectra at around 545 nm, 593 nm, and 613 nm when excited at 378 nm. The energy-transfer mechanism from Tb3+ to Eu3+ in Ba2P2O7 is determined by a dipole–dipole interaction. The emission intensity of Ba2−xP2O7:xEu3+ was enhanced by doping charge compensation Li+, Na+ and K+. The CIE coordinates of the phosphors can be tuned from blue-green through white, to yellow and finally to orange-red with changing the Eu3+/Tb3+ ratio. The average decay time of Eu3+ increases from 2.10 to 5.81 ms with the concentration of Tb3+ increasing from 2% to 8%, and reaches the maximum at 0.08, and is shortened when the concentration of Tb3+ goes beyond 8%.

Typical LED light sources have lower light utilization efficiency (LUE) in reflective directional illumination applications due to light pattern mismatch. Light patterns are generally controlled by secondary optical systems, which are heavy and large. Compared with the secondary optical system, the primary lens is smaller in size, lighter in weight, and more efficient in light extraction. This work is a preliminary study on the primary lens of LED in order to improve the LUE of LED in reflective directional illumination fields. Experimental result shows that the light extraction efficiency (LEE) of LED light source packaged by a primary optical lens is improved by a maximum proportion of 16.3%. The LUE of the LED packaged with the primary lens is up to 40.1% at 60°. After encapsulating the primary lens, the weighted mean angle of light intensity in the full space is at 57° which is bigger than that of LED without primary lens (46°).

In order to study the effect of joint clearance on the dynamic characteristics and chaos phenomena of the hybrid mechanism, 3-CPaRR Mechanism stability is related to the impact phenomenon between joint elements.

The novel red-emitting Na 3 Gd 2− x (BO 3 ) 3 : x Eu 3+ phosphors were synthesized by a solid-state method. Under near ultraviolet excitation, the phosphors exhibit dominant emission peak at 614 nm and generate bright red light, which is attributed to the electric-dipole transition 5 D 0 → 7 F 2 . The optimal doping amount of Eu 3+ in Na 3 Gd 2− x (BO 3 ) 3 : x Eu 3+ phosphors is x =0.3 for the maximum emission. The exchange interaction between Eu 3+ ions is identified to be the main mechanism in the concentration quenching process. The CIE color coordinates of the Na 3 Gd 2− x (BO 3 ) 3 : x Eu 3+ phosphors (x=0.650, y=0.350) are close to the NTSC standard values of red. With a relatively high quantum efficiency of 35.2%, Na 3 Gd 2 − x (BO 3 ) 3 : x Eu 3+ red-emitting phosphor is probably a promising candidate for near ultraviolet-based white LEDs application.

The phosphors Sr 3 Y(PO 4 ) 3 : Dy 3+ , Eu 3+ were synthesized by a high temperature solid-state reaction method in air atmosphere and their crystal structures, luminescence properties, lifetime, and energy transfer mechanism were investigated in detail. The co-doped Dy 3+ and Eu 3+ in Sr 3 Y(PO 4 ) 3 could enhance emission of Eu 3+ ions and a series of characteristic emissions of Dy 3+ and Eu 3+ were observed in the emission spectra at around 487 nm, 575 nm, and 615 nm when excited at 350 nm. It indicates that the energy transfer occurs from Dy 3+ to Eu 3+ and the intensity ratio of multicolor emission could be tuned by adjusting their concentration ratio on the basis of efficient Dy 3+ – Eu 3+ energy transfer. The energy-transfer mechanism from Dy 3+ to Eu 3+ in Sr 3 Y(PO 4 ) 3 is determined to be a quadrupole-quadrupole interaction and the critical distance between Dy 3+ and Eu 3+ is 15.22 A. The decay life time of the Dy 3+ ions decreases with the increase of the Eu 3+ dosage concentration.

A novel on-line vortex cooling powered by low-cost compressed air was proposed to reduce common defects such as low forming precision, coarse grains, and pores caused by heat accumulation in the Wire Arc Additive Manufacturing (WAAM) of aluminum alloy. The impacts of interlayer cooling (IC), substrate cooling (SC), on-line cooling (OL), and natural cooling (NC) processes were compared on the morphology, microstructure, and mechanical properties of as-deposited walls, revealing that the OL process significantly lowers the interlayer temperature and improves forming precision. The high cooling rate produced by the OL process reduced the absorption of hydrogen in the molten pool, lowering porosity. Furthermore, the grains are refined due to the developed undercooling. However, the high cooling rate enhanced the segregation potential of Mg element and raised the content of the &beta, phase. Conclusively, the maximum tensile strength, elongation, and microhardness of the as-deposited wall are achieved via the OL process, and the fine-grain strengthening mechanism plays an important role in improving mechanical properties. The OL process is cheaper and poses a significant effect, it is highly suitable for the additive manufacturing of complex components compared with other forced cooling processes.

A compact blue conducting mixed-valence Mo (VI,V) oxide film was grown on the surface of a carbon fibre (CF) microelectrode by cycling the potential between +0.20 and similar to 0.70 V SCE in freshly prepared Na2MoO4 solution in H2SO4 (pH 2). The thicknes

Electrodes modified with isopolymolybdic acid+polyaniline film, which exhibit high stability and activity in aqueous acidic solution, have been prepared successfully using two methods: one-step synthesis by electrochemical polymerization at a constant applied potential of +0.80 V/SCE or by cycling the potential at 100 mV/s between -0.12 and +0.85 V in 0.5 M H2SO4 containing 5.0x10(-2) M aniline and 5.0x10(-3) M H4Mo8O26, or two-step synthesis by doping the polyaniline film electrode with isopoly acid (IPA) under a cycling potential between -0.20 and +0.40 V in 0.5 M H2SO4 containing the H4Mo8O26 dopant. The thickness of the film and the amount of dopant in the polyaniline film can be controlled by experimental parameters such as the charge, time and the ratio of aniline to IPA in the solution. The experimental results show that electrodes modified with isopolymolybdic acid+polyaniline film using both methods have a strong catalytic effect on the reduction of chlorate anions. Comparison of the two methods of modification shows that the catalytic effect at the modified electrode prepared by the two-step method is greater than that at the electrode prepared by the one-step method.

In this paper a carbon fibre (CF) microelectrode modified with the 2:18-molybdodiphosphate anion by simple adsorption is described and its electrochemical behaviour is reported. The 2:18-molybdodiphosphate anion (alpha-P2Mo18O626-), which is a Dawson structure, undergoes five successive multielectron reductions in acidic solution. The first three redox waves correspond to the two-electron process, and the last two waves are four-electron and six-electron processes respectively. On the basis of the experimental results it is shown that the electrode process of alpha-P2Mo18O626- on the CF electrode in acidic solution is simultaneously controlled by the diffusion and adsorption of alpha-P2Mo18O626- anions. When the concentration of the alpha-P2Mo18O626- in the solution is reduced, the electrode process mainly exhibits non-diffusion-controlled behaviour, and the diffusion-limited process takes over as the concentration of alpha-P2Mo18O626- becomes higher. The CF electrode modified with a thin film of alpha-P2Mo18O626- exhibits very good stability and redox behaviour in aqueous acidic solution. The alpha-P2Mo18O626- is reduced to heteropoly blue, with an accompanying protonation process. The addition of more than six electrons to the alpha-P2Mo18O626- anion in an aqueous solution does not result in its decomposition. The result obtained is not the same as that reported previously.