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WRe/TZM gradient material was successfully fabricated simultaneously by spark plasma sintering technique with the gradient die to achieve the one-step bonding. The gradient sintering behavior and the effect of the sintering parameters on microstructure and mechanical properties of WRe/TZM joint were investigated. The results showed that the powders of WRe and TZM alloys could be densified and bonded simultaneously using gradient die to construct different sintering temperatures, and the relative densities of gradient material with WRe and TZM alloys were over 98%. The optimal joint with no pores and cracks was obtained at T = 1600 °C, t = 8 min and P = 30 MPa, under which the joint has the highest shear strength of 279.92 MPa. The Berkovich hardness of interface was mainly affected by the grain size and the solid solution of W and Mo. The resistance to creep at interface was between WRe alloy and TZM alloy. The joint exhibited excellent thermal diffusivity of 44.86 mm2/s. The WRe/TZM gradient material with excellent properties indicates this process is a promising technique route for fabricate the anode target for X-ray tube of CT scanner.

Directionally solidified (DS) LaB6 (001)-ZrB2 eutectic composite is successfully prepared by optical zone melting technique. The effect of the solidification rate on the microstructure and properties is systemically investigated. With the increase in the solidification rate from 20 to 100 mm/h, the eutectic rods present a homogeneous eutectic microstructure. The relationship between the average eutectic spacing and the solidification rate is established. The fracture toughness shows an obvious anisotropy. Crack deflection and crack bridging play important roles in improving the fracture toughness of the material. As the solidification rate is increased from 20 to 300 mm/h, the fracture toughness, bending strength and current density firstly increase and then decrease. The highest fracture toughness of 5.16 MPa.m1/2, bending strength of 809.04 MPa and current density of 36.24 A/cm2 at 1873 K belong to the DS LaB6 (001) - ZrB2 eutectic composite obtained at V = 100 mm/h.

The high-quality LaxCeyPr1-x-yB6 (x = 0.6–0.8, y = 0.1–0.3) single crystals have been firstly grown by optical floating zone melting method. The crystal structure, mechanical and thermionic emission properties of the as-grown single crystals were characterized by X-ray single crystal diffractometer, SEM, XRD, X-ray Laue diffraction. Subgrain-boundary-free [100] LaxCeyPr1-x-yB6 single crystal with a good crystalline integrity and homogeneous element distribution is obtained. The Lattice constant of LaxCeyPr1-x-yB6 single crystal is lower than that of the LaB6 single crystal. The lowest FWHM of 162.0 arcsec belongs to the La0.6Ce0.3Pr0.1B6 single crystal. The highest thermionic emission current density of 105.10 A/cm2 and the lowest work function of 2.562 eV indicate that La0.6Ce0.3Pr0.1B6 single crystal is a very promising thermionic cathode material.

The fuel economy and battery charge sustaining capability are two key criteria for the energy management of a full-power fuel cell hybrid vehicle equipped with small-capacity battery pack. In order to achieve stable battery charge sustenance and near-optimal fuel consumption, this study proposes an optimization-oriented adaptive equivalent consumption minimization strategy (A-ECMS) based on demand power prediction achieved via an iterative predictor. The proposed strategy updates the optimal equivalent factor periodically via local optimization process according to the predicted power to converge the state of charge (SOC) and guarantee fuel economy. The simulation results show that the iterative predictor has considerable accuracy, and the correlation between the predicted data and the real data reaches up to 0.987. The proposed strategy can quickly recover the battery SOC within 40 s in a 500-s driving cycle, which is shorter than existing feedback-oriented A-ECMS. At charge sustaining stage, the proposed strategy maintains the battery SOC around the reference value with an extremely low fluctuation degree of 0.36. The equivalent fossil-fuel consumption of the proposed strategy is 8.003 L/100 km, which is lower than that of existing A-ECMS. Besides, further investigation reveals that the proposed strategy has robust performance against the disturbance of power prediction errors.

Reactivity controlled compression ignition (RCCI) is demonstrated as a promising combustion strategy to achieve high efficiency and clean combustion. However, less effort has been devoted to examine the achievable RCCI operational range over a wide range of engine speed. In addition, previous studies have found that superior EGR rate and high diesel/gasoline fuel ratio are required to ease the extension of the low-load operating range of RCCI regime. Even then, relatively high CO and HC (unburned hydrocarbon) emissions and the accompanying fuel con-sum ption penalty still remain a problem to be resolved. Therefore, in this work the potential of diesel-fueled LTC to achieve simultaneously low NOx and soot emissions while maintaining high thermal efficiency at low load (IMEP ≈0.23–0.26 MPa) is investigated and compared with the gasoline/diesel RCCI strategy. The results show that the diesel LTC operation can yield slightly higher soot and NOx emissions (soot: 0.002 g/kW h, NOx: 0.446 g/kW h), but CO and HC emissions as well as the fuel consumption are much lower than the RCCI strategy, implying the diesel LTC regime may be more suitable for low-load operations. In addition, the RCCI operational range at speeds ranging from 900 to 2500 r/min is determined, the results show that the maximum achievable load (IMEP) increases with an increase in speed, and a maximum IMEP of 1.2 MPa can be achieved at an engine speed of 2300 r/min. Ultra-low NOx and soot emissions (soot