⑤ fill the substrate: When the spray coating to form the shell, the use of matrix material filled with real, the shell for support and reinforcement. The choice of matrix material, mainly based on the working conditions of the mold and the spray layer of different materials, choose different materials and processes. Mold on the substrate material requirements, should have a certain strength, to meet the working condition of the mold force requirements, easy to shape. As the spray shell is formed, its shape is more complex, the matrix shape must be closely matched with the coating, therefore, the filling matrix must have the characteristics of easy forming, to have a certain degree of thermal conductivity and heat resistance, while its thermal conductivity and thermal expansion Coefficient should be similar to the metal spray coating, especially when the mold temperature is high, it should be noted.