Materials Science Forum Vols. 575-578

Abstract: Processes of diffusion interaction between solid and liquid phases take place in such phenomena as wetting, spreading, dissolution, contact melting, liquid metal corrosion, changes of mechanical properties of metals and alloys being in contact with melts, etc. The knowledge of the mechanism and regularities of this interaction is necessary for development of such technologies, as sintering, self-propagating high temperature synthesis, impregnation, casting, welding, soldering, liquid metal cladding, etc. However, in despite of the fact that the problem of diffusion interaction between solid and liquid metals is of the paramount importance as for science as well for practice, no intelligible theory of the phenomenon is available. The paper fills the gap in our knowledge of this subject.

Abstract: The heat convection was considered the main heat exchange type in the autoclave where CFRP pressure vessel was cured in this analysis. To determine the heat convection coefficient, it needed the combination of theoretical calculation and temperature test. In the theoretical calculation, the determination of the heat convection coefficient was considered as an inversion problem of thermal conduction. By adjusting convection coefficient value in the finite element calculation, optimization method was employed to obtain a good agreement between calculated temperature and measured temperature. In the temperature test, the metallic liner of CFRP pressure vessel was used as test component to record temperature data which was compared with the calculated temperature. The calculated results reveal that the maximum value in convection coefficient sequence is 19.87 W/m2/K; the minimum value is 0.16 W/m2/K; the maximum temperature deviation between calculation and test is 1.67 °C. The results present the equivalent thermal boundary condition for the simulation of curing process of CFRP pressure vessel.

Abstract: In this paper, numerical simulation software of AnyCasting was adopted for simulate processes of titanium aluminum alloys filling and solidifying. Pour temperature, pressure head and rotate speed had an important effect on casting quality. The former parameters as factors orthogonal experiment L7 (33) was carried out and the experimental scheme was optimized. The results showed that as the pour temperature rising the filling time had no change, solidifying time had a large increase and casting defect tendency tended to little. Filling time and solidifying time decreased with the pressure head rising and casting defect tendency changed from little to large. The effect of rotating speed on filling time was as that of pressure head, solidifying time had little change and casting defects tendency of casting changed from little to great. With the optimized parameters of casting temperature of 1650°C, pressure head of 0.2m and rotating speed of 200r/min the investment cast filling and solidifying simulations was made out. The results showed that in the optimized simulation the liquid metal filled mold from the top down, filling course was smooth and complete and temperature field was even. Through analyses of casting defects the optimized scheme proved to be logical.