Titanium Alloy Investment Casting Technology

Titanium alloy is widely used in modern industry, especially in aerospace field, because of its low density, high specific strength, high temperature resistance and corrosion resistance. The casting technology of titanium alloy, especially the investment casting technology, is one of the key technologies for manufacturing titanium alloy parts with complex shapes. Investment casting technology, also known as lost wax casting, is a method of forming castings by using a soluble mold material to produce a mold shell and pouring liquid metal. This method is capable of producing castings with low surface roughness and precise dimensions, and has a high utilization rate of raw materials, which is almost unlimited by the type of alloy.
In the research of titanium alloy investment casting technology, the selection of mold material, mold preparation, dewaxing process, shell with the surface layer of refractory materials and binder selection are key links. Mold materials need to have a suitable melting point, softening point, good fluidity and good chemical stability and mechanical properties. At present, the commonly used moldings are mainly wax-based moldings and rosin-based moldings. With the growing demand for large, thin-walled and complex titanium alloy precision castings in the aerospace field, research and development of advanced die materials is also ongoing.

Die preparation techniques include traditional mold press wax and emerging laser rapid prototyping. Die pressing wax is suitable for batch and large-scale production, but it requires the preparation of molds for production, which increases the production cycle and R&D costs. Laser rapid prototyping does not require molds and can directly manufacture complex structural parts, but is not yet suitable for mass production.
Dewaxing process is one of the key processes in titanium alloy investment casting, and the commonly used dewaxing processes include solvent dewaxing, hot water dewaxing, high-pressure steam dewaxing, electromagnetic wave dewaxing and combustion dewaxing, etc. Each dewaxing process has its own characteristics. Each dewaxing process has its own characteristics and applicable scenarios, and choosing the right dewaxing process is crucial to ensure the quality of castings.
The selection of refractory materials for the surface layer of the shell is very critical to improve the quality of titanium alloy castings. Commonly used refractory materials include graphite, refractory metal materials, oxide ceramic materials and so on. Among them, oxide ceramic materials such as zirconia and yttrium oxide are widely used because of their good thermal stability and low thermal conductivity.
As an important part of the shell, the binder needs to have high thermodynamic stability, strong wetting and bonding ability, and good coating and molding ability. Commonly used binders include silica sol and zirconium diacetate. Silicone sol is expected to become the mainstream choice of binder in the future due to its low price, wide source and excellent performance.
Titanium alloy investment casting technology is developing in the direction of low cost and high quality, and future research will pay more attention to the development of new materials, process optimization, as well as environmental protection and sustainability. With the continuous progress of technology, titanium alloy casting technology will better meet the demand for high-performance materials in aerospace and other fields.