At present, graphite molds have been widely used in the following aspects:
Graphite molds for continuous and semi-continuous casting of non-ferrous metals
In recent years, advanced production methods such as direct continuous (or semi-continuous) manufacturing of rods or tubes from the molten metal state are being promoted at home and abroad. This method has begun to be used in copper, copper alloy, aluminum, aluminum alloy and other aspects in China. Artificial graphite is considered to be the most suitable material for continuous casting or semi-continuous casting molds of non-ferrous metals. The production practice proves that due to the use of graphite mold, because of its good thermal conductivity (thermal conductivity determines the solidification speed of metal or alloy), good self-lubrication performance of the mold and other factors, not only the casting speed is increased, but also because of the accurate size of the ingot, smooth surface, uniform crystal structure, can be directly processed in the next process. This not only greatly improves the yield rate and reduces the loss of scrap, but also greatly improves the product quality. There are two types of continuous casting methods: vertical continuous casting method and horizontal continuous casting method.
Molds for pressure casting
Artificial graphite materials have been successfully used in pressure casting of non-ferrous metals. For example, castings of zinc alloys and copper alloys produced from molds for pressure casting made of artificial graphite materials have been used in automobile parts, etc.
Graphite mold for centrifugal casting
Graphite molds have been successfully applied to centrifugal casting. In the United States, artificial graphite casting molds with wall thicknesses of more than 25 mm have been used to centrifuge bronze casings. In order to prevent the burning of artificial graphite molds, certain anti-oxidation measures can be taken. After casting a certain number of castings, if the inner surface of the mold is found to be burned, the size of the inner hole of the mold can be expanded to be used to cast large-gauge casings.
Hot Pressing Die Mold
Artificial graphite hot pressing die is used for pressure sintering of cemented carbide with the following characteristics: First, if the pressing temperature is increased to 1350-1450 degrees, the required unit pressure can be reduced to 67-100 kgf/cm² (that is, 1/10 of the cold pressing pressure); Second, pressurization and heating are carried out in the same process, and a dense sintered body can be obtained after a short period of sintering.
Molds for glass molding
Because graphite material has chemical stability, is not easy to be infiltrated by molten glass, will not change the composition of glass, graphite material has good thermal shock resistance, and the size changes with temperature is small, so it has become an indispensable mold material in glass manufacturing in recent years, and can be used to manufacture glass tubes, elbows, funnels and other special-shaped glass bottle casting molds.
Sintering dies and other diamond sintering dies
Taking advantage of the characteristics of artificial graphite material with minimal thermal deformation, it can be used to manufacture sintering molds and brackets for transistors, which has been widely used, and it has become an indispensable material for the development of the semiconductor industry. In addition, graphite molds are also used for casting iron molds, durable molds for various non-ferrous metals, casting molds for steel casting, casting molds for heat-resistant metals (titanium, zirconium, molybdenum, etc.), and thermite welding molds for welding rails. Graphite mold for hot-pressed sintered diamond tool plays a dual role as a heating element and mold support in the manufacturing process of diamond tools, and the quality of graphite mold directly affects the dimensional accuracy, appearance and shape of diamond tools. The requirements of hot pressing sintering process: the temperature reaches (1 000±2) °C, the molding pressure is 16~50 MPa, the holding time is 15~30 min, and the environment is non-vacuum. Under this working condition, the graphite mold of the forming and heating elements is not only required to have conductivity, high resistivity and sufficient mechanical strength, but also needs to have good oxidation resistance and long service life to ensure the dimensional accuracy and excellent performance of diamond tools. At present, graphite mold materials for diamond tool manufacturing in western developed countries are mainly graphite materials with ultra-fine particle structure, high purity and high graphitization, which require their average particle size to be less than 15 μm, or even less than 10 μm, and the medium pore size is less than 2 μm. The graphite mold made of this carbon raw material has small porosity, dense structure, high surface finish, strong oxidation resistance, and an average service life of 30~40 times. The diamond mold requires high material hardness, good oxidation resistance, high processing accuracy, etc., and the use of high-quality graphite raw materials greatly prolongs the service life of the mold and improves the oxidation resistance.