Research On Processing Of Functionally Gradient Disc-like Parts Of Aluminum Composites By Centrifugal Casting

The main task of this paper is to research the processing of functionally gradient disc-like parts by centrifugal casting. A set of vertical centrifugal casting experimental equipment which is composed of centrifugal casting machine, PLC controller, pouring equipment and lift device is designed and made in this paper. It is used to prepare disc-like parts with gradient SiC particles distribution in radial direction. The experimental material is homogenous aluminum matrix composite reinforced by SiC particles. The experimental process is that the revolving electric engine,which is controlled by PLC controller,drives the casting mould revolve then pour metal fluid into the mould when the engine is at appropriate rotate speed and form the parts. The extraction of castings and mould matching are completed by lift device.Design three different revolution technology diagrams of centrifugal machine varying as the time. The highest rotate speed is 800r/min, 900r/min and 1000r/min, separately. Total working times are 230s, 240s, 260s, separately. Input these parameters into PLC controller by instructions and make them correspond to program 1, 2 and 3, separately.To research the influence of parameters such as the rotate speed of electric engine, pouring temperature and mould temperature to the distribution of SiC particles, design three different pouring technologies. Sixteen disc-like parts are formed adopting these technologies.Observe the metallurgical structure and test area percentage of SiC particle of these parts casting by these technologies. The results show that gradient distribution of SiC particle is very obvious and area percentage of SiC particle reduces gradually from the border to the centre. It states that the higher of the mould temperature, rotate speed of centrifugal machine and pouring temperature, the more obvious gradient distribution of SiC particle. It could obtain the needed gradient distribution of SiC particle by changing the parameters.No. 5 part and No.7 part have been heat treated of T6 and T5, separately. And the hardness has been tested as well. The result shows that the distribution of the hardness is match with that of area percentage of SiC particle. It reduces gradually from the border to the centre. It shows that there is a direct relationship between the distribution of particle and that of hardness. The higher particle percentage, the higher the hardness.