During the forming process of carbon fiber composite pressure vessels, the parameters of the curing and forming processes become one of the critical factors affecting the production cost and forming quality. The curing temperature of 4251 A4/B2 epoxy resin is measured in this research, and the effect of curing temperature on the mechanical properties of composite materials for winding is studied, which is finally verified in the test of pressure vessels. First, the actual curing temperature of the epoxy resin is tested and analyzed using differential scanning calorimetry (DSC). Second, under two different curing regimes, the tensile and flexural properties are tested by making pure epoxy resin matrix test pieces, Naval Ordnance Laboratory (NOL) rings, and carbon fiber composite unidirectional plates that affect the overall performance of composite pressure vessels. At the same time, the test results provide reliable process parameters for numerical simulation and manufacturing of pressure vessels. Finally, the filament-wound 35 MPa type III pressure vessel is cured and carried out using a hydraulic burst test. The results show the resin matrix has good fluidity and excellent interface bonding with carbon fiber when the curing temperature is 112 °C. Compared with the results in curing temperature of 100 °C, the tensile strength of the NOL ring reaches 2260.8 MPa, up by 22%. In the 90° direction, the tensile and flexural strengths of the unidirectional plates increase by 68.86% and 37.42%, respectively. In the 0° direction, the tensile and flexural strengths of the unidirectional plates increase by 5.82% and 1.16%, respectively. The pressure vessel bursting form is reasonable and meets the CGH2R standard. The bursting pressure of the vessel is up to 104.4 MPa, which verifies the rationality of the curing regime used in the curing process of the pressure vessel. Based on the results of this paper, the curing temperature affects the fluidity of the epoxy resin, which in turn affects the interfacial bonding properties of the composite, and the forming quality of the wound components and the pressure vessel, ultimately. When using 4251A4/B2 epoxy resin for wet winding pressure vessels, the choice of a 112 °C curing temperature will help improve the vessel’s overall performance. This work could provide reliable experience and insight into the curing process analysis of pressure vessel manufacturing.
Rationally constructing nanoalloys achieving the synergy
of multiple
interactions among different constituents could substantially enhance
the electrocatalytic performance of an active metal for a given chemical
reaction. In this context, we design and synthesize well-controlled
ternary CuZnPd alloy nanoparticles, in which the Cu atoms modify the
electronic configuration of Pd atoms through the ligand effect or
the lattice strain effect, while the Zn atoms clean their neighboring
Pd sites through a bifunctional mechanism, and the synergy of these
two benefits endows the ternary CuZnPd alloy nanoparticles with exceptional
electrocatalysis for a room-temperature ethanol oxidation reaction
(EOR). In specific, at an appropriate 1/1/1 molar ratio for Cu/Zn/Pd,
the as-prepared ternary CuZnPd alloy nanoparticles exhibit both the
highest specific activity and mass activity of 17.3 mA cm–2 and 11.8 A mg–1, respectively, which outperform
those of their CuPd, ZnPd alloy counterparts and the commercial Pd/C
catalyst, as well as the majority of recently reported Pd-based catalysts.
Density functional theory calculations verify that the key CO* and
CH3CHO* intermediates generated during the EOR have the
lowest adsorption energy on the ternary CuZnPd alloy nanoparticles,
which is responsible for their boosted EOR electrocatalysis.
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