At present, there are two main factors restricting the development of 3D printing technology: printing materials and equipment. At present, 3D printing materials mainly include engineering plastics, photosensitive resins, rubber materials, photosensitive materials and ceramic materials. Its shape is generally powder, filamentous, lamellar and liquid.
Engineering plastics have excellent strength, hardness, impact resistance, resistance to aging. Photosensitive resins are composed of polymer monomers and prepolymers, which can cause the polymerization reaction to complete curing immediately under certain wavelength of ultraviolet light. Rubber materials, this material has a variety of levels of elasticity, it has hardness, elongation at break, tear resistance and tensile strength, making it very suitable for applications requiring non-skid or soft surfaces. Ceramic materials, with high strength, high hardness, high temperature resistance, low density, good chemical stability, corrosion resistance and other excellent characteristics, are widely used in aerospace, automotive, biological and other industries. Metal materials, three-dimensional printing of metal powder materials are mainly titanium alloy, stainless steel, aluminum alloy, superalloy, etc., in addition to precious metal printing materials. Among all the materials, titanium alloys are paid special attention because of their low density, high strength, corrosion resistance, high melting point, and they are ideal aerospace materials, especially suitable for the use of laser 3D printing technology. Stainless steel is the cheapest and cheapest 3D printing material at present. It is often used for 3D printing of jewelry and functional components. Superalloy has become the main 3D printing material in aviation industry because of its high strength, stable chemical properties, difficult forming and high cost of traditional processing technology.
The printing difficulty of metal materials is due to the high melting point of metal, which involves many physical processes such as solid-liquid phase transition, surface diffusion and heat conduction. The problems to be considered include whether the crystalline structure formed is good, impurities and void size, etc. In addition, rapid heating and cooling will also cause large residual stress in the specimen.