Characterization of brazed joints of C-C composite to Cu-clad-Molybdenum
Abstract Carbon–carbon composites with either CVI matrix or resin-derived matrix were joined to copper-clad-molybdenum using two active braze alloys, Cusil-ABA (1.75% Ti) and Ticusil (4.5% Ti). The brazed joints revealed good interfacial bonding, preferential precipitation of Ti at the composite/braze interface, and a tendency toward de-lamination in resin-derived C C composite due to its low inter-laminar shear strength. Extensive braze penetration of the inter-fiber channels in the CVI C C composites was observed. The relatively low brazing temperatures ( C/Cu-clad-Mo joints with relatively low thermal resistance may be promising for thermal management applications.
Microstructure and mechanical properties of C / C composite / TC 4 joint with inactive AgCu fi ller metal
The microstructure and bonding strength of vacuum-brazed C/C composite and C/C composite with inactive AgCu foil are studied. The interface structure of the brazed joint consists of the TC4/Ti2CuþTi(ss)/Ti2Cu/TiCu/Ag(ss)þTi3Cu4/TiC/C/C composites. The maximum shear strength of the joint is 33 MPa at 880 1C for 10 min and Ti diffusing from TC4 into the filler improves the wettability on the C/C composite. The interface evolution during the brazing process and associated mechanism are discussed. & 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.