1, aluminum silicon carbide material molding technology should have the conditions:
The reinforcement material SiC is evenly distributed in the metal matrix to meet the structural and strength requirements of the composite material;
The interface effect, hybrid effect or composite effect of composite materials can be brought into full play;
It can give full play to the reinforcing and toughening effect of the reinforcing material on the base metal;
Low investment in equipment, simple and easy process, strong operability; easy to realize batch or scale production;
It can produce a shape, size and structure close to the final product, reducing or avoiding post-processing steps.
2. Key technologies for forming aluminum silicon carbide materials:
Due to the inherent physical and chemical characteristics of metal, its processing performance is not as good as that of resin. In the manufacture of aluminum-based silicon carbide materials, some key technologies need to be solved, which are mainly manifested in:
The processing temperature is high, and adverse chemical reactions are easy to occur at high temperatures;
Poor wettability between the reinforcing material and the matrix;
Distribution of reinforcing material in the matrix.
(1) Adverse chemical reactions at high temperatures:
In the process, in order to ensure the wettability and fluidity of the substrate, it is necessary to use a very high processing temperature (often close to or higher than the melting point of the substrate). At high temperature, the interface reaction between the matrix and the reinforced material is easy to generate harmful reaction product Al4C3, which is brittle and will become the crack source of the overall damage of the aluminum silicon carbide material. Therefore, controlling the processing temperature of composite materials is a key technology.
The main solution to this problem:
①, as far as possible to shorten the high temperature processing time, so that the reinforcement material and the matrix interface reaction time is reduced to a minimum;
②, by increasing the working pressure to enhance the infiltration of materials and matrix speed up;
The diffusion bonding method can effectively control the temperature and shorten the time.
(2) The problem of poor wettability between reinforced SiC and matrix aluminum:
The poor wettability of the reinforcement material and the matrix is another key technology in the manufacture of aluminum silicon carbide materials. The substrate has poor wettability to the reinforcement material, and sometimes no wetting phenomenon occurs at all.
The main solution to this problem:
①, add alloy elements, optimize the matrix composition, improve the matrix to enhance the wettability, commonly used alloy elements are: magnesium, silicon and so on;
②, the surface treatment of the reinforced material SiC, coating a layer of coating can inhibit the interface reaction, can effectively improve its wettability, surface coating coating methods are more, such as chemical vapor deposition, physical vapor deposition, sol-gel and electroplating or chemical plating.
(3) The problem of uniform distribution of reinforced SiC in the matrix:
According to the structural design requirements, making the reinforcement material SiC evenly distributed in the matrix is also one of the key technologies in the manufacture of aluminum silicon carbide materials. Especially in the low volume aluminum silicon carbide stirring method, vacuum pressure infiltration method, powder metallurgy method, the agglomeration of SiC particles, and the uniform distribution of SiC particles of different sizes is a difficult point.
The main solution to this problem:
①. Appropriate surface treatment of the reinforced SiC to increase the speed of impregnation of the matrix;
②, adding appropriate alloy elements to improve the dispersion of the matrix;
Apply appropriate pressure to increase its dispersion;
④. Apply external field (magnetic field, ultrasonic field, etc.).