A unique method for curing composite materials by introducing vibration treatment into the hybrid heating process

Carbon fiber reinforced plastics provide many excellent properties and are widely used in the aerospace industry.However,the existing composites autoclave process still faces difficulties such as high-energy consumption,uneven distribution of temperature field,complications of pressure transmission,and high cost,which limit their application in manufacturing of large complex composites components.In this study,the vibration treatment was introduced into the composites microwave curing process innovatively.On the basis of giving full play to the uniform heating characteristics of the microwave,the problems of a large number of internal defects and poor molding quality caused by the insufficient curing pressure have been solved.The results showed that the samples cured by the improved microwave process without external pressure had a few internal voids,excellent interface bonding conditions,and lower residual stress.Their properties were almost consistent with the samples prepared by the standard autoclave process,which provided a new method for the high-performance,efficient,safe,and low-cost manufacturing of large complex composites components.

Microstructure evolution and mechanical properties of Mg-12Zn-2Y alloy containing quasicrystal phase fabricated by different casting processes

Although icosahedral quasicrystal phase(denoted as I-phase)has been verified as an outstanding reinforcing phase,the mechanical properties of quasicrystal-reinforced Mg-Zn-Y alloys fabricated by traditional casting processes are still unsatisfactory due to the serious segregation of intermetallic compounds.In this study,the microstructure and mechanical properties of Mg-12Zn-2Y alloy fabricated by different casting processes,including permanent mold casting,squeeze casting and rheo-squeeze casting with ultrasonic vibration,were systematically investigated and compared.The results show that massive,large-sized I-phase and Mg7Zn3 phase gather together in the permanent mold cast sample,while the squeeze casting process leads to the transformation of I-phase into fine lamellar morphology and the amount of Mg7Zn3 decreases.As to the rheo-squeeze casting process,when the ultrasonic vibration is exerted with power from 800 W to 1,600 W,theα-Mg grains are refined and spheroidized to a large extent,and the lamellar spacing of the eutectic structure is significantly reduced,accompanied by some tiny granular I-phase scattering in theα-Mg matrix.However,when the ultrasonic power continuously increases to 2,400 W,the eutectic structure becomes coarse.The best mechanical properties of the rheo-squeeze cast alloy are obtained when the ultrasonic power is 1,600 W.The microhardness,yield strength,ultimate tensile strength and elongation are 79.9 HV,140 MPa,236 MPa,and 3.25%,which are 44.1%,26.1%,25.5%,132.1%respectively higher than the corresponding values of the squeeze casting sample,and are 47.6%,44.3%,69.8%,and 253.3%respectively higher than the corresponding values of the permanent mold casting sample.